Please welcome our 1st curator - Drew Evans (@ScienceByDRE ) 🥳 Drew is a an associate research professor at the University of South Australia @UniversitySA. Know more about Drew ("from electron transfer to production line") : https://t.co/qmAeCMHjqp
RealSci_Nano Tweets
Every tweet posted by the curators of @RealSci_Nano, 2019 to 2024, by year and curator.
RealSci_Nano was a rotation curation account. Each week, a new materials or nanoscientist took over the account and shared their research, their life in the lab, and their questions. It ran alongside the Under the Microscope podcast, and many curators were also podcast guests.
In 2024 I closed shop on Twitter/X and moved to Bluesky, so the account now lives on as Under the Microscope. This page keeps every post the curators wrote, grouped by year and curator, so the work doesn’t disappear with the platform. For the full story, see the RealSci_Nano project page.
2019
Drew Evans
RT @ScienceByDRE: From tomorrow, tune in to @RealSci_Nano to hear about a world of conducting polymers, metal alloys, advanced manufacturin…
Hi, I am @ScienceByDRE and will be with you for the week. I'm a Materials Scientist/Engineering working in @UniSAFII @UniversitySA. I enhance the performance and manufacturability of thin films. My side role - anything to do with getting science out of the lab into industry.
Looking forward to taking you into the world of electrical/optical properties of materials, vapour deposition, and scaling that up into products with industry. Working with great ppl studying #ConductingPolymers and #MetalAlloys - as thin film coatings.
RT @realscientists: This is a really interesting read - I might have time to get into some metrics discussion this week - the journal impac…
To kick start the week I'm going to touch on something our team thinks long and hard about. It's not just the technical, but also the way in which we work. This helps us do fundamental research on the nanoscale and get it out to Industry. https://t.co/Y9wVFX3h7g
This often requires a bit of self reflection to understand the "why" behind our research. For everyone it is different. Here's an (old) interview outlining how I figured it out. https://t.co/Iz4tAGZMOc
One area we study involves nanofilms of metal alloys. We use magnetron sputtering to engineer these materials directly on plastic substrates. This is an example of how we developed these for use in the world's 1st plastic automotive mirror https://t.co/aO92FJ3jrQ .@IOPscience
This work was partnered with SMR Automotive in Australia. To date over 3.5 million mirrors are on the F250 from Ford. Our nanocomposite alloys now in a commercial product. So many ppl involved, in particular @ColinJamesHALL @Zuber_Kamil @ScottAEd1
RT @MySci_PK: Have you checked out https://t.co/UE1Zf5uDCj website yet? @RealSci_Nano https://t.co/bSHWrCxM03
Another aspect of my role has been working alongside some very generous people in the @EMCRForum. The exec team volunteer a lot of time to support and advocate for the future of Australia's science.
Being part of a wider group driving change in our sector to create a more welcoming inclusive environment. Critical to get the diversity of thought and opinion to tackle some of our great global challenges. Volunteering for the benefit of the wider sector can be very rewarding.
To round out the day and intro to me....... just as exciting as work is home life. Home now to the family to help. Easier at the moment with school holidays (so no after school activities).
Finding balance is very important. And balance means different things to different people. A challenge is how to make time to turn off your brain. That rest and relaxation is useful to be #productive and #efficient in #research. I'm yet to master this. #WorkLifeBalance
RT @OlgainAus: I'll be curating in a month or so! If #nanotechnology is your thing, then sing up 👇👇👇 https://t.co/AuRJIM03Zz
RT @realscientists: @realsci_DE @RealSci_Nano [Admin] @RealSci_Nano is taking applications for curation! @MySci_PK is coordinating our nano…
Tuesday has rolled around, and I thought I'd talk about #ConductingPolymers A rather unique material with a mix of properties between polymers, semiconductors and metals. https://t.co/z8IzlAbGG1
Interestingly the polymer properties can be modified by inserting or removing dopant ions from its structure. They can be made insulating through to conductive.
Many researchers exploit this for applications - not just conductivity. Think electrochromics, thermoelectrics, sensing, bioelectronics, optoelectronics.
An example of this is work we are doing with @SentekTech around sensing for agriculture Here's an explainer (20 min mark onwards) from my colleague @DrSamRudd about our #AgTech https://t.co/YjDspVXXeJ
@SentekTech @DrSamRudd Another behaviour we study is their optical switching behaviour - electrochromics. This property is driven by low power, and we get different colours by changing polymers. My colleague @Zuber_Kamil studies the nanoscale mechanisms behind this. https://t.co/l4pQXAJ4RU
RT @ScienceByDRE: Getting ready for tonight - Raising the Bar Entrepreneurship - #rtbeadl @RTBEvent Dusting off my thinking cap - warming…
RT @ScienceByDRE: @PatchouliW @MySci_PK @RealSci_Nano 😉 We are also working on metallic looking materials that are insulators for some coo…
Tonight I'll be up in front of (hopefully) a crowd in a pub talking about researchers helping industry. Helping them go from idea to product. Getting out to talk to the public is a good way to share your science. https://t.co/WN7xqVan7C
Tonight was a fun opportunity at #RTBEADL @RTBEvent in Adelaide. Told some stories about how we navigate the intersect of research and application. A good night out. https://t.co/Y7B4Qs53QH
RT @RuthEShaw13: Getting some top notch tips for researching with industry from @ScienceByDRE #RTBEADL https://t.co/WPxVElO6cb
This morning I thought I'd talk a bit about the science behind our materials. And how we study them. The core of this is the interplay of chemistry and structure on various properties.
For eg, our metal alloy films (40-ish nm layer) we use X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) to look at the atom arrangement and orbital interaction. This dictates a lot of the mechanical, optical and electrical properties. https://t.co/fmXaRSM2p7
Similarly we use these to look at how structure and chemistry define properties of conducting polymers. https://t.co/J4k995dZf4
Understanding how molecules and atoms arrange and interact on the nm scale is key to designing materials. From that different properties can be achieved. We then use that to make new devices with industry. Linking them together is an exciting space. https://t.co/HRMRptNqe4
In another study we used techniques to get details on the electrical properties of our materials. Such as studying the density of states and charges in a polymer. From this we uncovered semimetallic polymers. https://t.co/vUW3bBNNmg
More recently this has led us into looking at how different anions influence the properties of the polymers. Not totally sure yet what's happening, but appears to be specific ion effects. https://t.co/zb5HYBuYFL
This opens the door to exploring sensing. As we have done with nitrate using a polymer called PEDOT. https://t.co/VlLtKF4eaH
RT @MaterialsDan: @V_Saggiomo @RealSci_Nano
@ScienceByDRE @UniversitySA [admin] The extended podcast with @ScienceByDRE is now live: https://t.co/Y07b1E2mXM Here, Drew candidly explains his research #InOtherWords and has interesting 3 wishes to improve his research experience😉
[admin] Where do find the podcasts you ask? Here is a quick walk through 👇🏽 https://t.co/muM4T3B5fV
RT @RealSci_Nano: @ScienceByDRE @UniversitySA [admin] The extended podcast with @ScienceByDRE is now live: https://t.co/Y07b1E2mXM Here,…
RT @MySci_PK: Get over the hump day, check out #MyFavEM where the wonderful science behind gorgeous pictues (of tiny stuff) are explained.…
One big aspect of making our materials is understanding how they form. A technique we use is Vapour Phase Polymerisation (VPP). http://dx.doi.org10.1016/j.pmatsci.2017.01.004
There's more to it than simply polymerising a monomer. On the molecular scale we have controlled reactions at the liquid-vapour interface. The interface is structured using non-ionic copolymers.
This is a trick borrowed from colloid chemistry. In one form used to make mesoporous metal oxides. We use the structure to direct how the conducting polymer grows directly on the substrate. By changing the structure we can drastically change the polymer properties.
The nice thing about this process is we can (somewhat) control; - how the polymer forms on the nanoscale - over large areas (up to m2) This works for oxidative polymerisation of any volatile monomer.
Understanding processes like this helps us bridge the fundamental science with commercial manufacture. We do a similar level of work on magnetron sputtering and chemical vapour deposition.
For example, understand how processing of dielectric films can enhance their properties for certain applications. https://t.co/EF2vObMRZa
Fun fact: We name our coating equipment after objects in our solar system. We do sputtering in Saturn, Mars and Jupiter. Yes, Jupiter is the big machine. We do conducting polymer coatings in Callisto, Io and Europa. Our thermal evaporator is called Mercury. https://t.co/TtuzSn0OtF
From a busy day doing a lot of admin, squeezed some science in somewhere, it is time to get jobs done at home. Cooking dinner with my wife. Life never stops.
Great thread 👇 Traveling for work............ https://t.co/sZwO0dYFRr
It's Friday. I figured I'd raise a challenge facing many researchers - work with industry or do fundamental research? More specifically, can you do one only? Or both? What does it mean for your career, and meeting the 'metrics' for promotion?
Many industry engaged projects have a long lead time to publish, if at all. Considering intellectual property, confidentiality, trade secrets, and so on. This poses a challenge when an academic researcher needs publications.
This is particularly relevant for Early Career Researchers. They are less likely to have other avenues to publish. But also less likely to have employment length to see an industry project through.
So what to do? One thing to note is research is done in teams. Get a good group of people around you. Together you'll figure out how to do it. Also, make an end-user is part of that group. Someone who can help you shape your research to be relevant to industry.
This still doesn't answer whether you can do both. I found that early in my career it is very hard to do. But not impossible. It takes a lot of time to plan strategically how it all goes together. What is core fundamental and what is applied research?
Then comes the next step - who pays? Neither funding agencies or business have endless money to fund research. So make an assessment of which to focus on first. You can't do everything from day one.
A key thing I have learnt is that the path from idea to products is not linear. Some of my best (IMO) fundamental research came from questions in an industry project. So maybe think backwards about products and ideas. Working with industry may spawn your basic research.
Time...... How do you balance it? How do you allocate it?
As I try to get out with my kids to do the grocery shopping; I've spent several hours of Saturday morning working. After a week predominantly spent doing admin, and helping others at work....I find the time to do 'my stuff' gets pushed out of hours when I want to be not working.
Many academic roles have scope creep. The slow expansion of your tasks, including increased contribution to the greater sector. Boards, committees, panels, etc. All worthy things. But does it impact your day job? Time for teaching or research?
Or even more importantly, is it forcing you into decisions about out of work hours choices? Everyone is different. Everyone balances things differently. How to manage the expectation to 'do it all'?
I've been lucky these past years that out of hours work is infrequent. Others are not so lucky. This is a challenge I see for the sector. A research career should not have to contain sacrifices (unless you want to).
Is this something people in your local area discuss? Keen to hear how others manage this in their situation.
Another discussion about balancing your time - @realscientists https://t.co/Bp0jw4bhGq
@realscientists Speaking of scope creep. Every stopped to think how it may he impacting you? Or impacting your colleagues? A thought provoking article. https://t.co/kW23L7NSVR
Signing off It has been fun sharing some of our materials science with you. Plus highlighting challenges that I'm keen to help ppl overcome. You can keep following me @ScienceByDRE
RT @FromPhDtoLife: Working outside academia after a PhD is...
[admin] Thank you Drew (@ScienceByDRE) for kickstarting this account dedicated to nano/materials science! https://t.co/HQk6b9e0Gu
Michele Celebrano
@ScienceByDRE [admin] Please join us in welcoming this week's curator - Michele Celebrano (@vynisle) Know more about Michele on our website: https://t.co/cQQTigUrNn Oh, and do listen to the podcast! 🎙️
RT @vynisle: Dear Friends, from tomorrow all next week I will be the curator of @RealSci_Nano...if you fancy to know a bit more about what…
RT @vynisle: Here are the curator of @RealSci_Nano! Apply to be the next curator if you want to help sharing a bit of nano-science! And fol…
Good morning everyone! We you go abroad for conferences or other scientific meetings are a light traveller or a heavy one? In other words are you like "one pair of trousers and two shirts are more than fine for the week" or you stuff all your belongings in the luggage? https://t.co/0Ll6MblKfZ
So, yes. As you can imagine I am literally incarnating the stereotype of the Italian...I need 3 pair of shoes at least and I need to know that I might need to change dress for the evening. What about you?
Getting back to science, this is the Auditorium Gutenberg where I had one of my first conferences, SPP3 the conference on #surfaceplasmon. @Plasmonica https://t.co/7jVloeRDQD
@MartinCaldarola Know what you mean!... Worst part is, some colleagues think I am weird, but I think they are weird Italians!😂
RT @realscientists: One of the things that draws me to the study of volcanic lightning is that overall it's still a relatively new field (i…
@Plasmonica Well, I guess not everybody is in the field so let's see. What is an SPP (surface propagating plasmon)? Is a quasi-particle also called plasmon-polariton which is the oscillatory motion of free electrons at a metal-dielectric interface and its associated electromagnetic wave. https://t.co/eeLx34vXRW
Similar this one...a quasi-particle half wave half pizza! https://t.co/EhnkzLaK1l
RT @upulie: #NobelPrize for #MedicinePhysiology announcement due in 14 minutes - who will win this year?
Welcome in a Nano-Optics Lab. Here at @univbourgogne I am visiting accademic... to teach students and investigating nonlinear properties of plasmonic nanoantennas! https://t.co/bKjuBplYbH
And here is the back of the lab. Where all the laser beams get ready to be coupled to the microscope! https://t.co/aqiv6YGocT
... And you are not in a real lab if there are no pending wires all sound the place!!! https://t.co/eQb6AAdAHj
@ScienceByDRE And you are definitely more comfortable and fast to pack than me... But I can't avoid changing shoes for the occasion. It's a bug I know!
@ScienceByDRE For example, today lecture...I need my English shoes...😅😅 https://t.co/qW3poXTwSD
Good thing of preparing a lecture on your topics of study is that if you are also wiring a review on that you have figures already prepared! https://t.co/36NlWHGIRE
BTW, I will be giving a lecture on Harmonic generation at the Nanoscale this afternoon! I see if I can get some content via Twitter!
RT @upulie: #NobelPrize 2019 Medicine and Physiology https://t.co/v0wjKZGYKo
RT @NobelPrize: “Grant proposal deadlines wait for no-one!" Sir Peter Ratcliffe sitting at his desk working on his EU Synergy Grant applic…
RT @NobelPrize: BREAKING NEWS: The 2019 #NobelPrize in Physiology or Medicine has been awarded jointly to William G. Kaelin Jr, Sir Peter J…
At 2 pm I will give a lecture on Harmonic Generation at the Nanoscale! Stay tuned...in worst case you have some pictures!
In order to rise the number of followers I have to do this!!! Here is one of my neighbors office ... #Kittens!!! https://t.co/PdFXblmfTy
Playing with harmonic generation at the Nanoscale! https://t.co/wDFbTfliVi
Here is the live streaming of my lecture on Harmonic generation at the Nanoscale! Just the half bit on plasmonic because, since I talk a lot, the phone battery went off 😅 https://t.co/wDFbTfliVi
This was one of the most exciting lecture since it gave me the opportunity to share my research in some terms with highly motivated master students! https://t.co/bzW70dZkBy
RT @NanochemistryI1: Just out in @ACS_AMI: "Tunable Near Infrared Localized Surface Plasmon Resonance of F, In co-doped CdO Nanocrystals" h…
I defintely hate running, it is the last sport I would like to practice... But when you are abroad is the most affordable. And I am also branded @polimi so thought it was worth sharing this moment of @RealSci_Nano @univbourgogne https://t.co/uPgSOgx0LM
RT @MySci_PK: @RealSci_Nano is looking for curators! 😁 https://t.co/V8O6c1tt46
@MySci_PK I thought it was perfectly fitting!
(moment of self advertisement... And science) Let me introduce you one of my favorite gifs... Infact is the pinned gif of my profile @vynisle! https://t.co/6ry7XXFDaR
[admin] How to listen to the episode #3 of Meet the Curator podcast 🎤🎧📢 you ask?! Here is how 👇🏽 https://t.co/qIxTZeTMW4
Thank you Admin!!! Love this instructions!
Announcement time! In 2020 there will be an extremely interesting conference! Where? ONLINE! This is the first Photonic Conference free of charge and free from traveling cost!!! Join the community! @PhotonicsMeetup #POM20 https://t.co/j9YD9EYwYE
Another day of visiting starts @univbourgogne. Coffee, good music, some nice notes for lectures and of course the badge to enter the building! #AcademicTwitter #academiclife https://t.co/BW4oPxWAbt
Ok, it is not a very fancy building but... On the back there you have the most wonderful wineyards in the world... After some of the Italians 😉 https://t.co/C96t131fiR
#Nonsciencefact: in Bourgogne there make the most fantastic wines in the world. Burgundy wine is typically obtain by only two grapes Chardonnay for the white wine, Pinot noir for the red.
The wineyards are classified into Regional, Village, 1ere Cru and Gran Cru. And I don't have to tell you what is more prestigious. Soon it will become UNESCO patrimony and wine price will likely rise! So hurry up!
@MySci_PK @univbourgogne Of course!!! And eliminated the equations which were obviously wrong!
Good thing about group meeting in France...pain au chocolate! And croissant with the marmelade of my mum. Great combo! https://t.co/gMP8JmuB1V
I am particularly happy to be the curator of @RealSci_Nano in the week of @NobelPrize! Well I hoped to have some prize in optics to celebrate... However Well Deserved!!! Still some hope for chemistry. https://t.co/SxJwOFxFa8
Lab visit this afternoon. Interesting science going on in the laboratory Carnot @univbourgogne. Monitoring molecular Dynamics with ultrafast lasers and metrology with fiber optics! https://t.co/PAWiTE2Pt2
Look! The smallest autocorrelator I have seen so far! https://t.co/5mlJ668qEv
Autocorrelation measurement is used to measure the length of ultrashort pulses. This is often achieved by using the pulse itself through a nonlinear optical effect, usually Second Harmonic generation (again harmonics 😉).
Infact you cannot use a simple electronic device to measure a femtosecond (10^-15 sec) pulse since you would need some 100 THz electronics, which simply does not exist.
These guys here invented an alternative method that employs a Fresnel bi-prism to split the beam and measure interference fringes generated by two photon absorption on a simple camera! So time become space...Easy peasy!
Ok, I know you want some action! Here is a time lapse in the lab. Recording dark field spectra from #Plasmonic #nanoantennas with @rjulianomartin1! @univbourgogne https://t.co/0jURY7SQdC
@MySci_PK I also start with "How are you?". A bit less formal but leaves open doors for negative answers...
🎊🎊150 followers!!!🎊🎊 Come on you can do better! Of course I say it for the community...😏 Ok, encourage you something interesting on Harmonic Generation at the Nanoscale! https://t.co/ajHQ3phDQK https://t.co/oe8AYJiVAY
In this paper for the first time we find that in a single nanoantenna the generation of a third harmonic "note" of light, which is odd and therefore often naturally produced by the fundamental harmonic, here is generated via two times the distorsion of the second harmonic "note"!
While this can be very common in bulk crystals using a lot of power, here it happens already with very low power...in other words you don't need to pinch your guitar like an heavy metal guitarist to have crazy sound!
@MySci_PK @vynisle Yeah, well, maybe my research is a little less of impact and I don't have such high standards...anyway we both study physical mechanisms...😅😅😅 Thank you anyway @MySci_PK for the generous parallel! #travellingscientist
And that's a clear answer to my tweet of yesterday about the Physics Nobel Prize. Optics is all around! #NobelPrize #optics #photonics https://t.co/apINJBtWgK
Here some of the Nanofab facilities in @univbourgogne! Not simply a tour but testing some sample fab with Scanning Electron Microscope (SEM). https://t.co/Tu3MRYaaom
By the way, did you know that the old cathode TV were essentially a Scanning Electron Beam? So lab technology at home!!!
[Thread] Let's see some applications of harmonic generation in nanoantennas: Second Harmonic For Sensing https://t.co/IQokj3FTbF @JPhysChem https://t.co/0nW91VpJMa
And since few things nowadays are really original, here is the paper that inspired our study... Or that we found out to be already out when we were measuring (scoop): https://t.co/rncmvhy0wm
What I love about these two papers on that they do not have an happy ending ... No paradigm shift of sort! Scientist should more often have the possibility to report non positive results!
Oh! This is a good one. Real impact on society!!! https://t.co/Moq2WQ3vIT
@johnmdudley @FemtoSt @sylvaingigan Well!! That's very interesting since we were planning to get Besancon involved for LiNbO technology in our project on frequency doubling with Metasurfaces! I know probably you don't work with nano and LiNbO, we could get in touch...
@johnmdudley @FemtoSt @sylvaingigan And I got some very nice Savagnin from Jura here!
@vynisle The charging is often happening if you have isolating substrates. Electrons gets stuck onto the surface and cannot escape... Of course we knew and used a conducting polymer that can be than remove.
@vynisle However, this polymers are not as conducting as a layer of carbon, which will be the best solution but b will compromise the sample forever.
[admin] The wait is over! Epi. #4 Meet the curator is out now! This is an extended version of the conversation with this week's curator @vynisle the podcast can be found on our website 👇 https://t.co/cQQTigUrNn
These are my three wishes. My 5 cents on #researchlife! Maybe a bit too anti-meritocratic and with a different angle on gender issue... https://t.co/0K3UqCj3Ui
1. I did not quite yet understood why Europe is granting ERC for fundamental science and the most important part is the impact and disruptive nature of the project. If it is fundamental it is expected to face the unknown. So I wish real basic research would be more funded.
2. I would love that there would be less super-hype journals in favor of some “Journal of Reproducible Results”. We are publishing too much and too many papers out there are not well double-checked.
3. Too many times people focus on equality, erasing differences between gender or population. I think diversity is a great asset and if gender or race comes with some differences this is just an added value to life and therefore to science. Give real value to diversity.
And this is the late morning activity! In the afternoon we did something more challenging... Stay tuned!! https://t.co/GIlKa27EGi
Isn't it wonderful? An OPO almost at work... Always wanted one but all friends that have one warned me. Is one of the toughest thing to make lase properly! https://t.co/Axe0Xw3TDm
OPO stands for optical parametric oscillator. Is a laser cavity which is pumped by a seed laser. Via nonlinear optical process (here again harmonic mixing) produces a other laser beams. The challenge is that it has to be perfectly looked to the seed...
And here is about 1 hour in 30 second. Attempt to allign it! As always the boss comes and misalign everything and then the postdoc @rjulianomartin1 has to take over and re-allign 😂😂😂 https://t.co/iLdWQiuaEC
Tomorrow I promise you will see it lasing!
Today is my turn to try and make the OPO to lase! No luck for now... First time with an OPO thoug! #lasers #photonic #optics https://t.co/jB1Zdk5pUg
@MySci_PK You seem to have missed my thread yesterday! 😂😂😂
A bit of Dijon where I spent the last month close into the lab... But it is a wonderful city to have a stroll around! https://t.co/Wg8sWLsH8o
The back of the cathedral. https://t.co/ezLNG5X2xE
The @therudemuse in Dijon is a quite unique jem in the heart of the city. It contains a mastodontic sculpture dedicated to the French revolution whose copy is on top of the Arc de Triomphe in Paris! https://t.co/v5GDSgICEA
Hey, Photonic people! You don't have to miss this first experiment of online Conference! Low cost and low impact on environment...and yet super high standards!! Apply to get a POM-Hub at you rinstitution! #POM20 https://t.co/UgJF33c4RD
Trying to get inspiration for the perspective paper I am writing with some of my recent favorites songs @kekkofornarelli Do you use music for inspiration? #music and #science https://t.co/uXhoyydfSF
And the last day is over! Thank you @univbourgogne for hosting me! We could kick off some new ideas for the future! Looking forward to come back soon! https://t.co/ycVjhun0k2
RT @MySci_PK: @RealSci_Nano If YOU are a materials/nano scientists who is intersted in communicating your work, do volunteer to curate the…
After a last wonderful dinner in Dijon. I go back to Italy. By the way did you know that there are some refractometric techniques that allows you to determine the exact amount of sugar and alcohol in the wine? https://t.co/n28hXCLP5j
Here is a portable device for just 20 bucks you can get on Amazon if you are nerd enough! https://t.co/ycs8clqNgv
If you happen to listen to the chat we had with ADMIN @MySci_PK (BTW 👉👉👉https://t.co/cQQTigUrNn👈👈👈), we talk about harmonic generation and Metasurfaces. Here is an interesting example by @AluAndrea @CUNY https://t.co/iLdOrRkdD9 https://t.co/8qhiygdkC6
Stay tuned! Finally a gender swap soon! https://t.co/ERGpT6QX2D
Here some other very interesting material for #Metasurfaces! Structuring LiNbO... This is a great work by @MarkoLON group.https://t.co/IkiRchdSRj Hopefully soon we will have some nice stuff coming out of our Nano-Optics lab! Work in Progress. Stay tuned on @vynisle. https://t.co/mA5JDxGP43
Flying soon to Milan! Stay tuned for some Tweet from Italy! https://t.co/eBRTbMatQL
And again another recent very nice result on #Metasurfaces and harmonic generation... Here is the metamixer. @SandiaLabs https://t.co/EyqZXdBCdw https://t.co/mng5nNq3S1
RT @PhotonicsMeetup: THREE more POM-hubs for #POM20 — in Linköping, Sweden @liu_universitet, in St Andrews, UK @PhysAstroStAnd, and in Pisa…
Quite naturally on Monday I will start some exciting measurement on #Metasurfaces an Third #Harmonic! What is your research topic? Share it with the community! Become a #realscientist curator! @RealSci_Nano https://t.co/ANtMHxjatQ
Let me introduce you the #PhysicsFactlet by @j_bertolotti. One of the most fun and instructive moments on Twitter for me! This is an example of the interesting factlets you can find. Two coupled nonlinear (wow that's new this week) oscillator sinchronize in anti-fase! Huygens. https://t.co/KGZzaHapVZ
That's a great news! Congratulations @DNeshev and @igordownunder. Go Meta! #Metasurfaces https://t.co/nSymnISEmt
RT @KatsGroup: Check out the revised version of our preprint, "Wide-angle spectrally selective absorbers and thermal emitters based on inve…
[admin] Fun fun fun conversation with this week’s curator @vynisle and here👇🏽 is where you find it on the website! Link: https://t.co/cQQTigUrNn https://t.co/BiFNz1mgdt
Back home. Lazy Saturday. Recovery from the trip. Looking forward to what's next on @RealSci_Nano https://t.co/tVH1nbxrEW
Check out this one on nonreciprocal Metasurfaces! https://t.co/odmCZw18Ac
@MySci_PK Just planted... It will not stay like this for long! 😭
And here is a trivia! What is this? Hint: I recently visited the ultrafast spectroscopy labs in Lyon! (Ok, this is a big help!) https://t.co/Bxp88FeMMU
@MySci_PK Nice Pranoti, I love it!!!
@Ariel_Levenson That is for you to judge. Hope not. 😉 Here I meant that this is a little quiz. Can you guess what is it?
Well, I am not sure isn't a fake, but maybe with the right synchro and frame rate...@MySci_PK https://t.co/C0Bc9oESMB
@MySci_PK And you can see very well the harmonic distortions!
@thecrzyphysicst @MySci_PK Shutter speed and frame rate, really close there!
@thecrzyphysicst @MySci_PK Thank you so much for sharing! And confirming!
Hi everyone! It was a real pleasure to be part of the @RealSci_Nano community... And I will still be! Last post: remember, we are extraordinarily privileged to work with our passion. But never abuse it. There some extraordinary person waiting for you home too! https://t.co/Dg6kgAJ5u9
And beware, if you make three last post, she is going to start to use her phone too!!! 😉
Signing off! Bye, and welcome to @svenja_lohmann!
@vynisle Join us in thanking Michele Celebrano (@vynisle) from @polimi for the wonderful week full of interesting plasmonics and travelling scientist tweets. https://t.co/sflGE6X7HK
Svenja Lohmann
@vynisle @polimi [admin] Please welcome our next curator - Svenja Lohmann (@svenja_lohmann) who will take over this account from tomorrow! "Ion race through crystals/thin-films" more info: https://t.co/YDd4lyBggP
God morgon from Sweden 🇸🇪 My name is Svenja and I’ll be curating this account this week. Looking forward to tell you all about my research and my life as a PhD student!
During this week I plan to tell you all about how we can use accelerators for studying materials. My plan for today: introducing myself and the Tandem lab where I’m working.
Let me get some coffee and then let’s get started! https://t.co/MquKMhjyqI
Hi again 👋 let me start by telling you a bit about myself and how I got here. As I said I'm now tweeting from Sweden but I'm originally from northern Germany. For my physics studies I first moved south (@UniOldenburg then @UniHeidelberg) before heading north for my PhD.
Since around 3.5 years I've been living in Sweden and doing a PhD in the Ion physics research group @uppsalauni (yes, I'm in my last year, no questions about my defence date please 😬).
I’m working very on brand in a building called Ångström laboratory. Our local café has the conversion to more common length scales handy: 1 Ångström = 0.0000001 mm or for this account 10 Å = 1 nanometer! https://t.co/GV5l5EO1Sq
This unit is btw named after Anders Jonas Ångström who both studied and worked @uppsalauni. There’s a small exhibition about him in the building (in Swedish though). https://t.co/UsnvwOAeAj
@uppsalauni But back to me and my reserach. So, how come that I'm curating an account for materials science (except the building name)? To be honest past me probably would have been surprised. As a student I found it really hard to choose a specialisation and...
...I've done student research projects in theoretical physics, medical physics and high-energy physics. I realised after a while though that I really enjoyed working hands-on in a lab and I've definitely became fascinated by accelerators + the diverse research you can do w/ them.
I'm now doing a PhD in a field where we use ion beams from accelerators for materials analysis (and also modification). But to be able to do this, we first need to understand the interactions between ions and matter.
My PhD project focusses on the interactions of very slow ions with materials (actually mostly the electrons in the material) but we get to that later this week.
As promised I will introduce you today to the lab I'm working in. To get you started, there's a very recent article about the lab and the wide range of research done here: https://t.co/TwKlyXeVps
Btw, there is a big conference on ion beam analysis going on this week. I'm not there personally but several of my colleagues are. I couldn't convince any of them yet to be active on twitter but other people are and apparently using the #IBA2019 hashtag! https://t.co/baa6dO45DT
Introducing the Tandem lab! This is where I do my experiments. The Tandem lab is named after our biggest machine - our tandem accelerator. The photo shows me in front of it! https://t.co/eGfpqwPZzv
Here’s a short video following the beam line from the accelerator to the end stations. You can see in the end how the initial beam line splits up into 6 different ones. We have a range of different set-ups for different analysis methods and the Tandem provides ions for them all. https://t.co/4G50n3VJuV
So, why do we need so many different set-ups? First, I should explain that the Tandem lab’s a Swedish National research infrastructure. That means that not only people from my group do experiments here but that researchers from all over Sweden (and abroad) can apply for beam time
That means that research questions and samples vary quite a bit - from coating materials to steel used in fusion research to DNA samples to backing materials for solar cells.
Additionally, all analysis methods have their strengths and weaknesses so often a combination of several is needed for complete characterisation of a sample.
When I say characterisation what do I actually mean? Here are some examples of what you can do with ion beams based methods: - find out which chemical elements are contained in a sample - and in which concentration
- atomic structure (is the sample crystalline?) For thin films (that means nanometre up to about 1 micrometre for us): - thickness, position or concentration gradient of layers
I will explain the principle of some basic methods tomorrow! Feel free to ask questions any time though! https://t.co/fRiEME1p1W
As mentioned in my intro thread, I’m focusing on slow ions in my research. So, I’m actually not spending too much time with the Tandem myself but rather with this machine! https://t.co/z9b8iVmDBp
Whereas the Tandem uses acceleration voltages of up to 5 megavolt, this platform ”only” reaches 350 kilovolt. The ions from here are used for analysis methods as well as for implantations.
This is the beam line I’m working on! It’s about 8 m long and spans two rooms! The “small” accelerator is a very relative size description... https://t.co/Y0MLf1F7iU
I just got home from my dance class💃🏻 Dancing is super important to me and I dance about 3 times a week. For me it’s the best way to balance out work!
As I already mentioned I moved abroad for my PhD. I really feel at home in Uppsala now but let’s face it moving countries can be difficult and isolating especially when you just start a job that takes up much of your thoughts and time.
Also, in an academic environment not just you but also your colleagues tend to move quite a bit. So for me it’s been really important to also find myself friends outside the university bubble. Starting a new hobby turned out to be a good way to do so!
Having a hobby (aka something fun, regular and scheduled) is definitely one of my recommendations for new PhD students. I wrote down a few more a while ago: https://t.co/Upp0RclvLM
RT @ProfRachelGaN: Oh look. The academic establishment can still manage to erase a woman even when she's just won a Nobel Prize. Blinks re…
@AtiyaahDollfie Tbh, I think it's a much better tradition than naming the lab after the PI.
Good mornings and welcome to the second day with me here! I’m not really a morning person so I usually avoid starting before 9 but I have a lot of teaching this week which means 08:15 classes! https://t.co/PkhUyVxF8v
I’m teaching in our introduction course for the new physics bachelor students @uppsalauni. The course is a mix of different lectures and seminars. This week it’s the students’ turn to give presentations.
They have all visited a researcher here at the Ångströmlab and are now giving a short introduction to the research they have learned about. It’s a bit of a challenge first for the researchers to explain their work on a level accessible to 1st semester students.
And then for the students to present this research understandable for the other students. I’m every year impressed how well they manage! https://t.co/H5htH2kDhR
Today we’ve learned about the cube of theoretical physics! https://t.co/dEP0072rrI
Next presentation will be about quantum mechanics in nanosystems. Stay tuned!
RT @realscientists: Certainly it is true of my experience that academic workloads can be difficult to manage, but, the variety in terms of…
Quantum tunneling and electron-electron interactions in DNA molecules - that was rather advanced material for 1st semester students. But well done!
The last group for today talked about magnetic domains and research on magnetic refrigeration 🧲❄️ A perk of teaching this course is for sure to hear about so many different research areas!
I had my own challenges with teaching this course. Since it’s on bachelor level, teaching language is Swedish! I started teaching when I’d only been learning Swedish for 1.5 years. It was definitely hard but it also made me learn so much more Swedish so much faster!
Now I’m teaching this course for the third time and it feels really good to observe my own progress.
@MySci_PK I wanted to. Even though I thought about teaching in English first 🙃 but about half of the PhD students in our department are not Swedish so finding people to teach in Swedish is much harder and they convinced me.
Yesterday I gave you a short glimpse of our lab. https://t.co/Lp2SlH7z43
I also briefly talked about which kind of research questions can be addressed with ion beam: https://t.co/elDgAp8omZ
Now I want to tell you bit more about some basic methods and how they work in principle. We start with maybe the most basic ion beam analysis method - Rutherford Backscattering Spectrometry!
Quick note on the side: Researchers love acronyms! So, we would just say RBS instead of Rutherford Backscattering Spectrometry for obvious reasons. However, please stop me if I should start throwing around acronyms and you don't get their meaning!
The principle of backscattering spectrometry can be understood as some kind of atomic billiards. We have a material that consists like all matter of atoms and we shoot an ion onto it. https://t.co/E6KD4KmZT7
If the ion and an atomic nucleus of the target material come close enough to each other, the positive charges repell each other and the ion gets scattered. https://t.co/k2INw5LX6Q
Like in billiards, the direction in which the ion gets scattered depends on the incident angle. In backscattering spectrometry we look as the name says only at particles scattered in a backwards direction.
Unlike in the game in our experiments the masses of our two atoms don't have to be the same. The masses of the atoms, the energy of our incoming ion (determined by the accelerator) and the geometry of the experiment all determine the energy of the ion after the collision. https://t.co/pDYC92mXRt
And this energy is what we measure! Since we know the beam we send in (energy and mass) and the geometry of our set-up, we can then calculate the mass of the atomic nucleus from which the ion scattered. And thereby we identify chemical elements in a sample!
@vynisle Thanks ☺️
RT @iamscicomm: Before beginning today's discussion, let's take another poll to figure out how #scicomm is generally shared. If your format…
This afternoon I had a meeting with the doctoral board of @uppsalauni. I’m one of the vice-chairs of the board for this year and I’d like to talk a bit about being active in student representation and why I think it’s important.
To start this conversation one has to have a look at the Swedish law on higher education. This laws guarantees students a vote in all decision making organs of a Swedish university. This means students have representatives on all level from department to the university board.
PhD students are full students from a legal point of view in Sweden (we’re also employees so we get the best from both worlds like a salary and student discounts 🙃) so we also have representatives and get a say in university matters.
I think this is super important. A university is so much more than just tenured professors and management! And all the voices need to be heard to create a learning + researching environment where everyone can thrive.
@uppsalauni PhD students are organised in PhD boards both at faculty and at university wide level to speak as the voice for the respective group of PhD students. These boards also appoint the representatives to university boards I was talking about earlier.
They also organise and support different kind of events from seminars to afterwork to help PhD students to connect to others.
A PhD can look very differently depending on the field. The doctoral board is there to have a voice for all PhD students at the university no matter their specific situation. We therefore consist of representatives from all faculties.
To wrap this up: The situation of PhD students in Sweden is probably a lot better than in other countries (in terms of rights and employment benefits). However, I think it's important not to take these rights too much for granted.
An example: Allowing scholarships instead of employment is a current (and reoccurring) discussion topic, which would not really be in our interest.
Additionally, it's not always straightforward to know and claim your rights especially when you're maybe in a stressful situation. The PhD boards (and ombudsman) are also there to give support and information.
Getting engaged in student representation has also been a lot of fun for me. I've been working together with a diverse group of nice people plus I learned tons about how a big organisation such as a university is working. I really recommend it!
Good morning! If you folllowed along yesterday you might have noticed that I did a lot of things other than research. Yes, doing a PhD often entails more things than just standing in the lab! I honestly find it hard sometimes to balance out all my activities. Any tipps?
I should add though that I'm actually only teaching one course running for around 2.5 months every year so the rest of the time it's one thing less and more time for research
Today I'm going to focus more on physics though! https://t.co/xUcDzje7aL
Yesterday I explained how we can use scattering to identify the elements contained in a sample: https://t.co/amOr0XGFQs
You might have noticed that in my explanation I only talked about one part of the sample atoms - the atomic nuclei. The thing is that these are actually very small even compared to the size of the whole atom. So atoms are mostly "empty"!
That also means that it's actually quite rare that an ion is backscattered from the first layer (or any layer) like shown in my illustration. More likely it travels further into the material. In this case we will need to look at the other parts of the sample atoms - electrons!
The ion also collides with the electrons. But cause electrons are much lighter than the ion (even hydrogen is 1836 times heavier), it doesn't change direction much and only loses a tiny bit of energy in every collision. https://t.co/QU4uXAg9Lg
But since they're many electrons and many collisions, this process noticably slows down the ion. Eventually the ion will stop inside the material if it is thick enough (how thick is thick enough depends on the ion energy and mass and the sample material)
Alternatively, the ion meets an atomic nucleus before it has lost too much energy and is scattered in the same way as from the surface. It can then travel back through the sample and we can detect it! https://t.co/88tsXcVAII
With enough understanding of the ion-electron interaction we can translate the energy lost to the electrons to information about depth. For example: we can determine the thickness of a layer or calculate the depth in which the ion will stop.
We call the average energy loss by the ion per distance travelled the stopping power. Since it's such an important quantity, all measurements of it are collected in a big data base: https://t.co/YIIntSxqOL
[admin] “Ion race through the crystals/thin-film” Listen to the podcast epi #5 Meet the Curator with @svenja_lohmann Link: https://t.co/YDd4lyBggP https://t.co/WNnfNf3tNG
So I talked quite a bit of theoretical background and measurement principles yesterday and this morning. But I guess you’re all excited to see more of my lab, right? https://t.co/VVv5rk8M9H
Scattering experiments can be done in quite different energy regimes and we have several set-ups based on this principle. But let’s start with high energies and continue where this video stopped. https://t.co/fDTn4YD8S9
After the switching magnet (in blue in the final shot of the last video) we now follow one of the beam lines to our RBS chamber https://t.co/gA3JvSy5Sx
Let’s talk a bit about what we see in these videos. First, all the beam lines (the metal pipes) and chambers you see are in vacuum. That means all experiments we do are happening in vacuum!
Remember when I said that ions are scattered and slowed downs by nuclei and electrons in matter? Well, that’s not only true for solids but also for gases means also air!
Since we want the ions to reach our sample as a focussed beam with the full energy we’d chosen, we work in vacuum! This way we also make sure we really measure the interaction with the sample material and not with air.
The experimental chamber was already under vacuum when I filmed the video but I have some photos from a while ago to show you how it looks inside. https://t.co/DkF3hhWeaX
The main thing you see here is the goniometer (=thing that can be rotated/moved around several axes). The samples themselves are mounted on a wheel. Here’s a photo of my hand holding an empty one to give you some idea about sizes. https://t.co/BHajrSo94A
And here are some pretty samples from a while ago getting ready to be analysed 🤩 https://t.co/bPIL0CW3uA
The samples I’m usually working with are super thin foils so they’re really sensitive to vibrations, draught etc. Taking photos of me holding a full sample wheel therefore don’t exist cause I rather put them into place quickly!
I will talk more about these samples and the research I do on them tomorrow. I'm actually working with slow ions so I'm doing most of my research with a different set-ups, which you might have already seen if you checked out the blog post! https://t.co/pBpne2taSs
@svenja_lohmann [admin] The extended podcast 🎙️ with @svenja_lohmann is out now. Here, Svenja gets candid about her favourite research project and research-exeprience-improving-wishes. 😉 Listen here: https://t.co/YDd4lyBggP
Thursdays usually start with meetings for me. We have a separate technical meeting for every accelerator where we discuss possible technical issues, changes to the equiment and the schedule for the upcoming week.
As I said we're a Swedish national infrastructure where also people outside our group can do experiments. Therefore everyone has to apply for beam time. We then usually make a schedule for the whole month. So I need to plan my lab time a little bit in advance.
Btw. I have beam time scheduled for tomorrow! https://t.co/K4XXkGkUra
Thursday morning is also the time to socialise with some cake and coffee. https://t.co/dl46JzQAHW
Today I wanna talk more about the project I’ve been working on for a good deal of the last year or so. To get started I first need to get back to some things we talked about yesterday.
I first talked a bit about how ions interact with electrons. https://t.co/WIf32PcgPO
In this context I introduced the stopping power. The thing is that the strength of this quantity (you can think of it as a force that slows down the ion) depends strongly on ion energy. Here is an example: https://t.co/99ON1O72fM
For various reasons (physics,technical, historical...) we understand much more about the high energy region of this graph. This is why my PhD project focusses on slow ions and how they interact with electrons.
Side note: this is also why I measured my samples at the high-energy set-up the other day. I characterise my samples (mainly their thickness and composition) first with a well-established method before I use them to learn about interactions at low energies.
These are super good questions because they very much lead to why interactions of slow ions are more complicated. I try to answer as good as I can. Please continue asking if something stays unclear. https://t.co/JXwTHgbuiM
1. The easiest case to consider is this: The ion is much faster than the electron in the atom and they get relatively close to each other. Then the Coulomb force between them is acting and momentum is transferred to the electron.
If it would be a free electron, the interaction would be like in the scattering case more or less billiard like. However, the electrons usually are bound and they have discrete binding energies in the atom.
So, if the energy transferred is not enough for the electron to leave the atom, it might still be transferred to a different energy shell --> the atom gets excited.
So far so easy. But there is more that can happen: If the ion is slow and/or heavy (i.e. has a high nuclear charge) it has a rather high chance to capture an electron. That means the electron becomes part of the travelling ion/atom (it might become neutral).
I try to explain this process in this tweet here: https://t.co/EnZRzkEnX9
Note that the reverse process is also possible, i.e. that the ion transfers an electron to the solid and becomes (higher) charged. This process depends strongly on how close the ion gets to the target atoms though cause the two electron levels needs to be resonant with each other
Then there is a process called "molecular orbital formation". Which means that the ion is so slow that for a time it seems like it's forming a molecule with a target atom. That has again an influence on the electron energy levels and thereby on the energy loss.
Considering this question: "Could we even discriminate between these possibilities, even theoretically?" Theoretically we can look at single events. Experimentally, we always look at the average of many collisions. There are some tricks though...
I pause here since I have teaching now. I leave you with this pretty image of one of my samples. I promise it has a lot to do with what I've been talking about in this thread and the trick I've just mentioned... https://t.co/A4S0Cbo2O3
Ready for experiments tomorrow! https://t.co/7GzkH2s6O7
Important reminder to myself (and everyone working with vacuum): vacuum pumps don’t pump faster if you stare at the pressure gauge...
Have you listened to the podcast yet? I'm trying to explain my research project on ion-electron interactions in crystals #InOtherWords. https://t.co/YDd4lySR8n
This was actually the first time I was interviewed like this and the first time I'm on a podcast! So I'm maybe a bit nervous and awkward even though @MySci_PK did a great job! Thank you so much!
So what's the trick then? And what does this image have to do with it? https://t.co/mEWTp9rBjJ
Our approach is to use very thin crystals and measure the energy ions lose by travelling through it. No, we still won't be able to look at single interactions but in this way we can at least look at specific paths the ion is taking.
This is how these crystals look like by the way. I use silicon crystals (the 2 outer samples) that are between 50 and 200 nanometre thin. The middle sample is not a crystal but a very thin SiN membrane as a reference. https://t.co/nEWtZw8sXK
@MySci_PK @svenja_lohmann Thanks 😊
RT @MySci_PK: Probably a good time to bring this thread back on the occasion of #GrapheneTurns15 https://t.co/GT0zfiWKA3
Are you ready to follow me along for a a day in the lab? https://t.co/yFNd1moGHf
I’m ready, but the beam is not unfortunately :/ So let me tell you a bit about what I’m planning to do today.
I’m planning to use neon ions today. Neon is a gas, which makes it relatively straightforward to use in ion beam analysis. In principle we can use all kinds of materials though but actually getting a beam might require some more effort. https://t.co/Bsl5Qd6ZZ2
So what we want to get from our neon gas are positive neon ions only. That means we need to separate electrons from the atoms, i.e. create a plasma!
The plasma is created in a part called the ion source and looks like this: https://t.co/JVD2iWILPt
Plasma is created by an electric discharge in the gas and for that we need to slowly ramp up the voltage in the ion source. This is what we were waiting for but now we have beam!
Sorry for the silence. This measurement day is quite exhausting to be honest since things are not quite working as they should. But hey that’s experimental physics 🤷🏻♀️
I got some nice results earlier today though 😊 https://t.co/TAQCVY6Ceb
I’d now like to repeat this measurement at a different energy. I expect that the effects I’m studying depend quite a bit on how fast the ion is so my usual approach is to measure under the exact same conditions expect with different energy.
So what do I do in a case like this? First thing is trying to realign and refocus the beam. We want the beam to reach our sample in a nice parallel and small spot. We have viewer plates along the beam line to help us. https://t.co/N3UgGSDxkj
It’s a bit hard to photograph but the blue spot is our ion beam!
Selfie of a confused scientist with beam line #ScientistsWhoSelfie https://t.co/tqZkrdGz7t
Top tip: have some coffee before you deal with problems! https://t.co/2GRZWziztl
And write things down in the lab book!!! https://t.co/x1Nwxjx5D8
I wanted to tweet more today but I have a cold and I'm not feeling that well. So I leave you with a photo of Uppsala being beautiful in autumn. Thank you for this week, especially to the @RealSci_Nano team! https://t.co/WsxjRUEAss
@medievalwishes Thank you :)
@svenja_lohmann [admin] Thank you @svenja_lohmann for the wonderful week full of "lab-tours" and explaining the science behind the "ion race through the crystals/thin-films" 😀 https://t.co/biNPzZRlHm
Olga Shimoni
@svenja_lohmann [admin] Please join us in welcoming this week's curator - Olga Shimoni (@OlgainAus) "Size Matters, in Medicine" To get an idea of what is coming your way this week, read the blogpost and/or listen to the podcast (Epi. #7) here: https://t.co/JjttNLWZFV
[Admin] This week's @realscientists curator is Teresa Ambrosio (@teresaambrosio_) Get ready to hear about chemistry, work/life balance and mental health. https://t.co/T78aEHpNVa
G'day #Nano enthusiasts! My name's Olga Shimoni, and I'll be curating this week's @RealSci_Nano from Sydney, Australia! I'll talk all things #nanotech, #medtech, #FunFacts, #Academia and #WorkLifeBalance. And this's a new friend that I met at the Kuringgai National Park today👇🏼 https://t.co/sCkkGzXUNv
About me: I’m A/Prof at the @UTS_Science and @UTS_Sci_IBMD, working on solving #health challenges using #nanotechnology tools. My research is on the application of #nanoparticles for #medtech. Or can we make #nanobots? https://t.co/lf2arY08n3
@UTS_Science @UTS_Sci_IBMD My research is on a particular emphasis on identifying diseases at an early stage. Why is it important to diagnose diseases at early stages? See statistics for cancer👇🏼👇🏼👇🏼 https://t.co/xuGYiWa9s4
@UTS_Science @UTS_Sci_IBMD But my work isn't only about cancer. My team develops #diagnostics for #alzheimersdisease, autoimmune disorders (#celiac), and few others.
#nanotechnology enthusiasts, do you know for how long #nanoparticles have been used as #diagnostic tool?
#FunFact Nature has been using bottom-up #nanotechnology in the biological processes of all living things for billions of years. https://t.co/uQjONyImxc
RT @MySci_PK: . @RealSci_Nano has crossed 200 followers! 😁 Thank you for supporting this form of science communication dedicated to materi…
@svenja_lohmann @OlgainAus [admin] "Size Matters, in Medicine" Extended podcast (episode #8) 🎙️ it out now. In conversation with this week's curator - @OlgainAus https://t.co/JjttNLWZFV
The final results are in! But the right answer is the official use of #nanotechnology in #medtech was since the 1990s! https://t.co/9ToEylQX30
#FunFact Do you know that most of the pregnancy tests involve gold #nanoparticles? #nanotechnology in #medtech https://t.co/g5qOBF8F9N
RT @b_fitzgibbon: ***SAVE THE DATE*** @EMCRBrainAu and @sahmriAU present the following live webinar on The Canadian Brain Research Strategy…
RT @realscientists: [admin] Are you a mateirals/nano scientist who wants to communicate science? Curate @RealSci_Nano for a week! Nomina…
How about a nano-guitar? #nanotechnology #rules https://t.co/kbS6j9h61M
#nanotechnology is a multi-disciplinary field of science where borders between physics, chemistry, biology, and engineering blur to build an exciting new field. My background in chemical, materials and biomolecular engineering and physics helped me to become expert in #nanobio
In my PhD I worked on #nano engineered capsules for cancer cell treatment and catalysis. #nanomedicine #FightCancer https://t.co/9UgakVLdaM
After Phd, I moved to a field of #diamond #photonics that basically means the study of beautiful colours of diamonds. But instead of these 👇🏽👇🏽 beautiful stones we studied #nano #diamonds. Hint: #scientists don't have money to buy big gems! 😜😜 https://t.co/Zl710v25m7
And eventually I could merry #materials chemistry, #photonics, #nanotechnology and #biology into #nanomedicine. Here are the red fluorescent nanodiamonds for bio-imaging! https://t.co/gneZgXkd7M
@svenja_lohmann @OlgainAus [admin] Thank you Olga for an insightful week about "size matters, in medicine". For more info, follow @OlgainAus https://t.co/7GAyBo41Ag
Steve Maguire
@svenja_lohmann @OlgainAus [admin] "Growing nanoparticles with magnets" please welcome this week's curator Steve Maguire @sciencenotscary 🎙️ Episode #9 Meet the curator can be found here: https://t.co/vceKPNJG1A
Hi, I'm Steve, you can call me Steve. <squints at picture> Wait, that isn't me yet.
Anyway, a little something about me. I'm a chemist and science communicator from Canada. I did a Masters in photonanochemistry at the University of Ottawa (@uOttawaScience).
Small confession: I finished in 2006 and haven't done a whole lot of nanostuff since then.
In addition to my https://t.co/4ASfUWWicg. research, I'll also be talking about how to survive grad school, what happens when things don't go entirely as planned, and how to communicate your nanoscience.
This is just a brief introduction. I'll be back a little later when the west coast of North America starts waking up (sorry, Rest Of The World and other inconvenient timezones.)
Before I start in on the research, I should tell you how I became a scientist. I knew I wanted to go into science at age 12 because of Star Trek. I watched TNG as an impressionable lad, and I was captivated by all the sciencey solutions to the problems of the week.
I say "sciencey" because once I started studying science for real, I discovered that all the Treknobabble was quite literally babble.
The character I identified with most was Wesley. I've met Wil Wheaton at a couple of cons and told him that, and he was absolutely thrilled. (I didn't tell him that the reason I identified with Wes was that I was the obnoxious kid that nobody liked.)
Poor guy's had to deal with a lot of undeserved grief over the years because of how terribly his character was written.
I didn't zero in on chemistry until grade 11. I had a great teacher, and something about balancing reactions and finding out what things are made of at the atomic level appealed to me.
I knew before I finished high school that I was going to take chemistry at university.
I did a Bachelor's degree in Kelowna, British Columbia, Canada at Okanagan University College, now called UBC Okanagan. I got interested in zeolites, which are essentially rocks with tiny channels in them where interesting chemistry happens.
I went to grad school at the University of Ottawa, because there was a prof there working with zeolites. I got accepted into his lab, and turned up on my first day to be given a project involving...not zeolites.
Instead, it was a project investigating oxidative stress in...something or other. I can't remember, because I was only on the project two days before discovered a paper describing exactly that project.
I couldn't do something that was already published, so my boss switched me to a different oxidative stress project...with the same result.
The third time turned out to be the charm. My boss found a paper describing making silver nanoparticles using light. He was a photochemist, and had done work on a photochemical system that would be much better at making nanoparticles.
I'm going to leave it there for today, because it's a little weird tweeting under someone else's name and picture. Tomorrow I'll describe my nanoresearch, and the trials and tribulations along the way.
#NewProfilePic
RT @sciencenotscary: I tried to throw a neutrino pumpkin through the detector, but it just smashed on the outside of the support structure…
OK, nano-time.
I started my Masters in December of 2003. Was that really 16 years ago?
I took an overnight flight to Ottawa from the other side of the country, and got no sleep.
When I got to campus, I went looking for the lab and was confronted by a sign that said "authorised personnel only." I stopped for a second, then thought "wait a minute, I'm authorised personnel."
As I mentioned yesterday, the first two projects I was assigned quickly proved to be already published. I can't remember exactly what they were, but they weren't nano, so they aren't important.
The third project was the charm. My supervisor was Tito Scaiano, who at that point had not had any interest in nano-anything. He was a photochemist, and had spent a lot of his career finding rate constants for various photochemical reactions.
He read a paper describing the production of silver nanoparticles in thin polymer films using light. The process took two hours, and resulted in an unpleasant brown colour. Tito figured he could do better.
Incidentally, explaining why the state of the art is terrible and you're so amazing is pretty standard in writing grant proposals.
Anyway, this paper described how their polymer film had molecules dissolved in it that would produce ketyl radicals in it that would convert silver salts into silver nanoparticles when hit by light. Cool. What does all that mean?
Let's start with radicals. Most organic molecules are held together by bonds between adjoining atoms. Each atom contributes an electron, and those two electrons are shared between the two atoms and form the bond. This is covalent, a term that might be familiar from highschool.
Generally, all of the electrons in the molecule will be paired up, either in a bond or just hanging out on one atom. Radicals are what happens when one of those pairs is sundered.
A radical is an unhappy molecule, generally, and it spreads that unhappiness around with a shovel. It wants its electrons to be paired, so it starts stealing electrons from other molecules. Which then makes more radicals. The circle of life.
The particular type of radical in this study is derived from ketones, hence the name ketyl (ket + -yl suffix). Great, what's a ketone? Hang on, let me find a picture. (Public domain image from Wikipedia user Benjah-bmm27) https://t.co/rGCDXzshIK
The big R groups simply represent chunks of molecule we aren't bothering to specify. The important part is the C=O, which represents a double bond between carbon and oxygen.
That's a carbonyl. This time the suffix is -onyl, and represents a double bond to oxygen. It's also pronounced differently. Here the y sounds like a long e (neel), and in ketyl it sounds like a short i (till). There's no rhyme or reason to this.
Anyway, when you have a double covalent bond, the electrons in the second bond are a lot more playful than those in the first. In addition, the oxygen has two more pairs of non-bonded electrons, so there are lots of options to steal one to make a radical.
Alternately, the plain ketone can steal an electron from another molecule and make itself a radical. This is where photochemistry comes in.
Electrons live in orbitals, which are mathematical descriptions of where electrons can be found 95% of the time. There's a lot of uncertainty about where an electron is at any given time, hence the elaborate math and stats involved.
Each orbital can hold two electrons...which is also the number in a covalent bond. This isn't coincidental. For the purposes of this discussion, the covalent bonds between atoms can be considered molecular orbitals.
Everybody keeping up? Do I need to go back and explain something in more detail?
OK, all of these orbitals exist at different energy levels, usually expressed relative to some arbitrary zero points. It's nearly impossible to measure absolute energies, so we just pick some point we can measure and call it zero. Everything else is relative to that.
All of these orbitals contain 2 electrons...but there are a bunch of empty ones as well. Whether or not they actually exist if they're empty is a question for the philosophers, but they're real enough that an electron can jump into one.
That's jump between orbitals is a quantum leap, if you're wondering where that term came from.
A quantum leap can only happen if an electron suddenly receives exactly enough energy to make that jump. Too much or too little, and it's not happening. In organic molecules with C=O double bonds, that energy can be delivered by UV light.
That's the basis of photochemistry right there: light carries energy, and molecules can absorb that energy if it matches the difference between one of its full and one of its empty orbitals. After that, chemistry happens.
So where does the nano come in? Patience, I'm getting there.
(This story is quickly becoming How I Met Your Nanoparticle.)
If that ketone absorbs a photon of light, one of the playful electrons in the C=O double bond gets booted up to a higher orbital. Once it's there, it can grab a hydrogen atom from a C-H bond of another molecule, and drag along one of the electrons from that bond.
Now that C=O is a C-OH, and that other poor molecule is now a radical, with the remaining electron from that C-H bond sitting sadly on the C. But what about the other electron left behind when the photon kicked the other one upstairs to start this process?
It's still there, also unpaired, sitted forlornly on the C of the C-OH. That's the ketyl: a radical derived from a ketone. Took a while, but we got there eventually.
After all that, why did we care about these ketyl radicals? It turns out that unhappy radicals can also make themselves happy by giving away that unpaired electron, if it results in something stable.
If our ketyl gives away its unpaired electron, now there's a big empty hole on that carbon atom. That hole can be filled by remaking that C=O bond. Currently it looks like this: +C-OH, where the + is the positive charge caused by the loss of the radical electron.
There are two electrons in the O-H bond. If the H takes off and leaves behind its share of the bonding electrons, those two can then pivot around and slam down into the hole on the carbon. C=O H+ There's a + on the H because now it's got a positive charge.
Clear as mud?
Half the reason the ketyl can give away its electron is because this stable, happy non-radical molecule is the product. Reactions generally want to end up stable and happy. However, the other half depends on finding something stable and happy to give the electron to.
Enter silver. Silver is a metal, and metal chemistry is quite unlike non-metal chemistry. For starters, metals tend not to* form covalent bonds. * - OK, some do under very particular circumstances, but not in the system we're considering.
Metals generally form ions by losing electrons. If you've seen corroded steel or copper, that's what's happened. The metal atoms in the solid metal chunk lost their electrons and were dissolved into any nearby moisture as freefloating ions.
Because the universe is electrically neutral, those positive ions need negative partners, which are usually formed during the corrosion process. Compounds made of these positive-negative ion pairs are called salts.
Silver is quite difficult to convince to become a salt, and quite eager to go back to its metallic state. It will accept an electron from any ready source. It will also do so if exposed to enough light, but that's not helpful to the reaction at hand.
Actually, it's actively unhelpful, which I'll get to when I talk about what happens when things go wrong.
Silver salts will accept that electron from the ketyl radical to become metallic silver...and that's where things get nano.
If you shine light on a ketone that's in a mixture of some sort with silver salts, you generate ketyl radicals which give electrons to silver ions that make silver metal, and those silver metal atoms glom together and grow into nanoparticles.
It was a long walk, but we got there in the end. Anyone still with me?
Tomorrow I'll carry on with my particular research project, and some pictures as well. As interesting as wall-of-text tweet threads are, metal nanoparticles are way too colourful not to show you.
As of 2012, the jury was still out, and I haven't heard of a verdict being returned since then. Best guess is local oxidation of surface gold atoms by the sulphur forming a covalent bond. tl;dr, <elaborate shrug> https://t.co/aPEydDGx8h
RT @realscientists: Today I’m working on a grant application for my experimental work on ticks. Scientists often need to submit multiple gr…
Good morning. It's just about 9AM here in rainy Sudberia. I'll do a brief recap for Europe and points farther east who were asleep while I was tweeting yesterday.
If you're just tuning in, I did nanoresearch between 2004 and 2006 at the University of Ottawa. I haven't quite got to exactly what I did yet, because I was explaining how radicals worked.
If you take a covalent organic molecule and slice a bond such that each fragment gets one of the electrons in that bond, you end up with radicals: molecules with an unpaired electron.
Things with unpaired electrons tend not to be happy, and they spread that unhappiness around with a shovel.
Normally this unhappiness is manifested by the radical shredding another molecule in search of electrons to pair with. This just results in the formation of another radical from the wreckage.
Sometimes two radicals will find each other and peacefully combine their unpaired electrons to form a new bond. This stops the make-a-new-radical chain reaction and is called the termination step. These two things are common in reactions that grow long-chain polymers.
Finally, and most relevant to the discussion at hand, a radical can sometimes give away its unpaired electron to something else, if both resulting molecules end up happy and stable.
A radical can give away its electron if it can rearrange itself afterwards to fill the hole left behind. This usually requires the formation of double bonds, and requires a source of mobile electrons within the structure of the molecule.
I covered this in detail in yesterday's thread. Let me go find and retweet the starting point.
This is where I describe giving away an electron to form a stable molecule. I, uh, don't know how to weld it into the existing thread. Sorry. https://t.co/katmLWmZUg
Having a stable product left over is good, but you also need something that wants to take the electron. Silver is a metal that really wants electrons, and will do it quite readily. It will grab them some other metals, or whatever else it can find.
It does need a bit of help to get started. That help can come in the form of light. Silver salts are photosensitive. The entire pre-digital photography industry was built on this premise. Film and photographic paper were coated with light-sensitive silver.
If you put silver salts in close contact with these radicals, you can grow nanoparticles quickly and easily. Well, I say quickly and easily, but it still took me a year and a half to figure out how to do it.
OK, let's pick up where we left off: growing silver nanoparticles.
But first, tea, Earl Grey, hot.
There are a bunch of ways to grow nanoparticles. The simplest brute-force approach is to smash a chunk of bulk copper into nano-sized pieces. This is a lot harder than it sounds, and highly discouraged.
(If you're following this account, I'll assume you're already reasonably familiar with nano-related concepts, so I'm not going bother with the usual comparisons to some miniscule fraction of the width of a human hair.)
A much better way is a ground-up approach, where you start with silver in salt form and convert it into metallic silver, which then self-assembles into nanoparticles. There are several ways of doing it.
A simple chemical way is to throw something at it that will do that reaction spontaneously. You have to do it in a controlled manner, otherwise you'll end up with a mirror on the inside of your beaker.
This is an old way to test for the presence of a class of organic compounds called aldehydes: Tollen's test, or the silver mirror test. It's also how they used to make actual mirrors: take a slab of glass and spray silver salt and aldehyde on the back of it.
I need to digress into some fundamental chemistry again. I've been talking about metallic silver and silver salts. Going from the salt form to the metallic form is called reduction, which is the opposite process as oxidation. Everyone remember LEO the lion says GER?
That works too. https://t.co/k9D6jid9wx
Silver in salt form has a charge of +1, and in the metallic form it's 0. These also correspond to the oxidation state. When it gains the electron, the state is reduced from 1 to 0, hence reduction.
"Oxidation" is a holdover term from the early days of chemistry, when the compounds they were studying got more oxygen atoms glommed onto them. The term it more broadly applied now to any reaction where the oxidation state increases.
Anyway, making nanoparticles from salts is a reductive process, and requires a reducing agent, some other chemical that serves as a source of electrons.
Making silver mirrors is as simple as throwing them together. Making nanoparticles requires some way of persuading them to grow to nano-size and then stop. We usually add yet more chemicals called capping agents, because they cap the growth.
Something like sodium citrate acts as both reducing and capping agent, and is readily available and fairly inexpensive, so it's a popular choice.
The citrate molecule physically binds to the surface of the growning nanoparticle, stopping its growth and preventing it from agglomerating with any other nanoparticles. You get a nice golden-yellow solution rather than brown crud.
I've made both. The yellow stuff is much prettier.
It's one of life's little ironies that silver nanoparticles are gold coloured, and gold nanoparticles can be just about any colour except gold.
True. One of my successors in the Scaiano lab managed to grow a whole variety of different colours due to size and shape with selective illumination of previously synthesised AgNPs. https://t.co/f1vMT7WKa3
Incidentally, it's surprisingly hard to find good images of silver nanoparticles in solution. I know there's one in my thesis, but I'm not currently anywhere near the computer that the document is stored on.
I took this image from @ScaianoGroup 's website. It's from the work of Kevin Stamplecoskie, who's now a chemistry professor at @QueensChem. The shapes above each vial are the shapes of the nanoparticle responsible for each colour. https://t.co/rZcT8iqV6l
The numbers are the wavelength of light he used to irradiate the starting nanoparticles. For those interested, I'll put the paper citation in the next tweet.
K.G. Stamplecoskie and J.C. Scaiano, “Light Emitting Diode Irradiation Can Control the Morphology and Optical Properties of Silver Nanoparticles”, J. Am. Chem. Soc., 132 (6), 1825-1827 (2010); DOI: 10.1021/ja910010b.
The particles they grew ended up absorbing at the wavelength of light used to grow them. This was a surprise to Tito, because generally in photochemistry, if you irradiate something that absorbs at a specific wavelength, that thing goes away (this is called photobleaching).
But I'm getting ahead of myself. I haven't talked about my research yet, and I've skipped to work that built on it.
Where was I? Oh yeah, capping. Another way of capping particles is to make them in a polymer film. If the polymer is made up of subunits that can double as capping agents, you have plenty of things around to stop the growth.
It's also harder for the particles to float around and find each other, so agglomeration is slowed. This is about a page away from where I enter the story. Tito, my https://t.co/4ASfUWWicg. supervisor, read a paper describing the photosynthesis of AgNPs in a polymer film.
(AgNP is just a shorthand for silver nanoparticle. The same pattern is used for gold nanoparticles, AuNP).
It took them2 hours of irradiation to make an ugly brown film. Turns out polymers aren't great at stopping agglomeration after all. Tito knew he could do better, and he had a new Master's student in need of a project.
(That was me.)
He showed me that paper, and one he's published in the early 80s about making ketyl radicals in micelle cages. That other paper had used ketyl radicals as their reducing agent, but not very efficiently. I talked about ketyls yesterday.
He suggested I try making AgNPs using his micelles. Wait, what's a micelle? I made a video about it: https://t.co/teRVNRuwlW
Word of advice for anyone who may want to make videos: if your nose is itching, you may want to take care of that before you hit record.
Did I forget to mention that in addition to being a chemist, I'm also a science communicator? I'm a science communicator. Won a trophy for it, but that's a story for another day. <Ted Moseby's kids sigh and roll their eyes>
@upulie Cats are legendarily curious. There's even a saying about it that I'm carefully not quoting.
As the source of my ketyl radical, I used benzophenone (public domain image). The O on a stick in the middle is the ketone part, and the two hexagons are benzene rings, which are great for stabilising radicals. https://t.co/JqlXqhbULu
I dissolved the benzophenone inside the soap micelles, then threw light at it to make the ketyl radical. Yesterday I talked about how there needs to be some other molecule around with C-H bonds to make the radical. The long chains on the micelles served this purpose, but poorly.
I could make AgNPs, but they weren't pretty golden ones. My solution turned brown, indicating that they were clumping together. I didn't have a capping agent.
The system from the 80s also used a molecule called 1,4-cyclohexadiene (image made by me). Instead of grabbed a hydrogen and electron from the micelle cage, the benzophenone could more readily grab it from here. https://t.co/1ydf2v8t9r
See those two double bonds on either side of the ring? Remember, double-bond electrons are playful and can move around. If you generate the radical at the carbon between the bonds, you can smear it around the double bonds. Smearing makes unstable things happy.
It's the same reason the benzene rings on the benzophenone (BP) made the ketyl radical happy: you could smear it around the rings.
Not only did 1,4-CHD make it easier to make ketyl radicals, it also served as a capping agent. This was completely unforseen, and is one of my contributions to the sum total of human knowledge.
This is why scientists do science: to find things out that nobody knew beforehand. If I took a brown agglomerated sample and added CHD to it, the clumps would break up and it would turn yellow(ish).
With CHD, the reaction went faster, too. After 30 seconds of shining a light on the system, it changed from colourless to bright yellow. If you recall, the paper Tito read that started all this took 2 hours to make brown stuff.
Granted, it took me 18 months to get to this part. A year and a half of trial and error (mostly error). The day it succeeded, I went running down the hall to my boss's office with a vial of yellow liquid.
Note: it is highly discouraged to take chemicals out of the lab to your boss's office.
Note: in #scicomm, it is highly encouraged to inject some emotion into your communication. This is an example I use to illustrate that: being excited that something finally worked.
I am going to wrap up here for the day. I have to head out soon to take two puppies to obedience class, neither of which is my puppy. I have no idea how this happened.
I will carry on tomorrow and explain why the topic for this week mentions magnets. See you then.
Good morning Americas, good afternoon Europe, good evening Asia. (Australia, go to bed, it's a school night.)
Yesterday I got as far as running from the lab to my boss's office with a little vial of yellow victory.
I used to describe my research as shining a light on water and making it turn yellow. Every single person said "I can do that too, and I don't need the light." Three years of my life condensed down to a pee joke.
I had succeeded in making silver nanoparticles suspended in water, and had capped them so that they floated around by themselves and didn't all glom together. I even discovered a new capping agent. I should have been done, right? Nope. I still needed to turn on the magnet.
I'll explain about that after lunch.
@svenja_lohmann @OlgainAus @sciencenotscary [admin] "Growing nanoparticles with magnets" 🎙️podcast episode #10 out now: https://t.co/vceKPNJG1A
I'm back in the chair now and ready to carry on, but first I need to fortify myself with some hot chocolate. Because I'm 12.
Someone left a bunch of packets of mint-flavoured hot chocolate powder in the break room, so of course I'm going to have one. Because I'm 12. Anyone who thinks scientists are boring and stuffy has clearly never met a scientist.
So far this week, I've described using light to create a radical that can donate an electron to a silver salt and reduce it to silver metal. These metallic silver atoms can then grow into nanoparticles, provided something stops them glomming together or turning into a mirror.
The process of growing nanoparticles is more complicated that simple throwing stuff together. There are two main phases, and the being able to influence them allows greater control over the final product.
The first phase is nucleation. This is where silver atoms are formed from the salt and first come together in clusters. These are the nuclei that the particles grow around.
The same principle happens to snowflakes: water crystallises around something (usually dust particle or some other tiny piece of schmutz) and grows in a regular hexagonal pattern.
Controlling the speed and duration of nucleation allows you control over what the final product looks like. A fast burst of nucleation means you have fewer nucleation sites, which means you end up with fewer nanoparticles, but they tend to be larger.
A longer nucleation phase has the opposite effect: you have oodles of sites competing for a limited amount of growth material (in this case, silver), so they don't get as big. Controlling this during chemical synthesis is very difficult.
It's much easier to control if you can just turn a lamp on and off. Because reduction of silver only happens while the light is shining, you can start and stop nucleation with a flick of a switch. I usually gave it 15-30 seconds.
Photochemistry is just better than regular chemistry*. * - in this particular set of circumstances, under these conditions, offer not valid during months with an R in the name
Incidentally, if you're enjoying my irreverent sense of humour, you can find much more of it at @sciencenotscary, as well as videos about how science isn't scary. Oh, and neutrinos.
After nucleation comes growth. This can start happening before the end of nucleation In systems where all the growth material already exists, it can keep happening after the end of nucleation. For example, snowflakes will keep growing as long as there's moisture.
In my AgNP system, growth should stop as soon as the light shuts off and stops making silver metal, right? No, because of subtleties I haven't told you about. I hate trick questions, especially ones that rely on withholding information.
There's a minimum size that nanoparticles need to achieve in order to be stable and happy. If they're smaller than this, they simply fall apart, and the material is incorporated into larger particles in a process called Ostwald ripening.
Put another way, the big ones eat the small ones. In the nanorealm, it's survival of the fattest.
This is how you can get growth in silver nanoparticles even after the light has shut off. As long as there's a capping agent present, they'll stop growing before they pass out of the nanoscale and stay suspended in solution.
After 800 tweets with no pictures, I bet you're wondering what they look like up close. Wonder no more. Those are AgNP I made, imaged with an electron microscope. https://t.co/AnJ6zrNP86
Each of those dots is the top of a stack of silver atoms. Now you can say you've seen atoms.
You can see by the regular rows of atoms that the particles are crystalline. That's the definition of crystal: having a regular repeating pattern to its atoms. "Crystal" isn't a substance, it's a property of substances.
Saying something is made of crystal makes as much sense as saying a window is made of square.
If you look at the large particle right in the centre, you can see that the rows don't all go the same way. This one wasn't grown from a single nucleation site. Instead, a bunch came together and joined to make one nanoparticle, possibly during Ostwald ripening.
This is my favourite image from my thesis. I made the particles, and while I didn't acquire the image myself, I sat next to the guy who operated the electron microscope and watching him zoom in.
So where do the magnets come it? When I made my nanoparticles, it only took 30 seconds. If I did it with the vial sitting next to a magnet, it took 15. Taking 15 seconds off the synthesis time may not seem like much, but it made it go twice as fast. That's not trivial.
Why did the magnet make it go faster? We need to go back to radicals and their unpaired electrons.
An electron has a property called spin. This spin can point up or down. I didn't fully understand what that meant during my Masters, and I'm not sure I understand it now.
I once heard a particle physicist describe spin as "a property particles have." I'm not sure they fully understand it either, or what it represents.
It's usually shown graphically as an arrow stuck through a ball. The ball is the electron, and the arrow is the axis that the electron spins around. If the electron was a globe, the arrow would be sticking out of the North Pole.
This explanation is just simple enough to be a useful metaphor while simultaneously being completely wrong.
When two electrons form a bond or occupy the same orbital, the spins need to point in opposite directions. Why? Because. That's why.
This paired-up state is called a singlet. The name comes from the way electronic systems like this were studied. When something with no unpaired spins emits a photon, the resulting spectrum has a single line.
When something with a single unpaired electron emits a photon, the spectrum has a doubled line, or doublet. If we can get two unpaired spins, we get a triplet. The pattern is # of unpaired spins + 1.
Why? <embarrassed pause> Like I said, I didn't fully grok it then, and I've never had cause to come back and learn it properly.
Anyway, the important thing here is the triplet. I described how ketyl radicals form when an excited ketone rips a hydrogen and electron off another molecule, resulting in two radicals.
Those two radicals form a radical pair, especially if they're caged in micelles and can't get away from each other. The cage is important. The two spins can either point in opposite directions and form a singlet, or the same direction and form a triplet.
If they're a singlet, they can easily recombine and go back to the starting materials. Remember, two electrons can only occupy the same orbital if the spins point in opposite directions.
If they're a triplet, the spins point the same way, and they can't do this. This means the ketyl lives long enough to wander around, find its way out of the cage and meet up with a silver atom outside.
The more triplets there are, the more often this happens.
Thing is, the spin direction is not set in stone. The triplet can flip back to the singlet, which then results in recombination. However, it can only do this is the triplet and singlet states are reasonably close in energy.
This is where the magnet comes in. It turns out there are three different triplet substates, based on how the spins line up. If you can't picture that based on the arrow-in-a-ball picture, this is why I said it was completely wrong.
I can't actually describe how this works, so you'll just have to go with me on this one. I am deeply sorry.
Anyway, when you put this triplet radical pair in a magnetic field, one of the substates is raised in energy, one is lowered, and one stays the same. The corresponding singlet is unaffected.
What this does is move two thirds of the triplet substates far enough away from the singlet that they can't flip over and recombine. You've basically made two thirds of the triplet molecules immortal.
This means they have all the time in the world to float out of the cage and go play with the silver outside. More triplets getting out means the reduction reaction happens faster, which is why it only takes half as long to get nice nanoparticles.
But if 2/3 of the triplets are immortal, why is it twice as fast? Shouldn't those numbers match up better? Don't try to read too much into it. My irradiation times were fairly arbitrary, and I didn't try to accurately measure reaction rates.
If anyone wants to revisit this, go right ahead. Just remember to cite me.
This magnetic effect on the triplet state requires the two radicals to be caged together, hence the blob of soap molecules.
We made it to the end! And just in time for the end of the work day. If anyone wants anything clarified, please let me know. I'm pretty sure I glossed over a bunch of things.
There's no such thing as a stupid question. If you don't understand something, there are probably dozens of other people who also don't understand it, and you're all too shy to ask. Go ahead and ask. It might be because I didn't explain something clearly enough.
I'm going to head out now, but I'll check in again later tonight. Tomorrow I'll talk about the experience of doing research, and what happens when things don't go right.
Yesterday I brought my research story to its end: making silver nanoparticles with photochemistry, with a little help from a nearby magnet. If anyone wants anything explained in more detail, let me know.
Later today I'm going to talk about what happens when things don't go smoothly in grad school.
Research is hard. You're trekking into the unknown, often without a map or procedure to follow. Half the time you have to make it up as you go, and you don't know what you're going to find.
That's the exciting part. If we already knew what the answer was, there'd be no point in doing it. Finding out things that nobody else knew is one of the reasons I went into science. It's exciting.
It can also be incredibly frustrating, when you find yourself in your fifth blind alley in four weeks and feel like you're wasting your life in grad school.
Meanwhile all your friends are getting real jobs and buying cars and houses and starting families, while you're still a broke student at 28.
"A grad student is someone who forgoes short-term earnings in order to forgo long-term earnings later." In short, it's rough. I've been there.
I wasn't the most talented or assiduous researcher, either. The science I described this week should have taken about a month to sort out. I was a year and a half into my degree before I got good results.
My entire thesis was written from four months of data at the end. It was 100 pages of near-identical spectra.
I was having trouble getting consistent results. I'd make up my solutions, shine the light on them, and then take an absorbance spectrum to examine the yellow colour.
None of the squiggles in the spectra of the various tests lined up. If I was making the same thing every time, they should have all come out the same. A lot of of the times they would come out as near-random gibberish.
My boss was not happy. I set a date for myself that if I didn't get good results by then, I'd withdraw from the program. I pulled it off at the 11th hour. The stars aligned, and everything worked.
But it was nerve-wracking as hell getting to that point.
My PhD, which wasn't nano-related and is beyond the scope of this account, was even worse. I couldn't get any publishable results at all. I failed two meetings with my thesis committee. I ended up having to leave the program, which is why I'm not Dr. Steve.
At the time, I was trying to write up while teaching in a little town in Ontario. They'd hired me on the assumption that I'd eventually get a PhD. I don't think I told them I withdrew, and they didn't seem to care.
The job was covering someone's maternity leave, and my first year chemistry class had 7 people in it, so I don't think they wanted to go to the trouble of finding someone else mid-semester.
Anyway, 2013 was a low point for me. My PhD imploded, my personal life collapsed and I was living in a slum in small-town Ontario, earning peanuts despite having a graduate degree. It turned around.
At the end of my contract, as I was starting the jobhunt all over again, a great job fell into my job through the Knowsaguy Network. (As I, I know a guy who knows a guy who knows a guy...)
For the past five years, I've been a chemist on a neutrino experiment at @SNOLABscience in Sudbury. This is the coolest and weirdest job I've ever had.
@SNOLABscience There isn't a lot of nano involved, so I won't go into much detail, except to mention that at one point we thought we might be making tellurium oxide nanoparticles (spoiler: we weren't, although I would have been uniquely qualified to look into them if we had.)
@SNOLABscience The point I'm getting at here is that leaving grad school is not the end of the world. Definitely stick with it as long as you can, if for no other reason than to be able to tell yourself that you gave it everything you could.
I was lucky in that both my advisors were supportive and genuinely wanted me to succeed. There are a lot of abusive PIs in academia who will work you to the bone and then discard you. If you're in that situation, you don't have to stay. There's a better place for you.
Grad school is also tough if you have obligations outside of it, like a family to support. Health and financial security also make it hard to succeed. Academic culture makes unreasonable demands and expectations.
14-hour days, 7 days a week sound like commitment to science, but really it's a good way to cause rapid burnout. Your work quality suffers drastically after about 8 hours. Anything more is counter-productive.
Good luck convincing your overbearing PI of this, though.
It's currently snowing here in Sudberia, but it's melting when it hits the ground, so it's still T-shirt weather.
I forgot to explain what it was that made everything work. Remember when I said silver was photosensitive? Photograph development used to be done in dark rooms, because otherwise excess light would ruin the pictures.
Turns out excess light will ruin nanoparticles as well, or at least ruin your control over the reproducibility of your experiments.
I would dissolve my silver salt in water, and then leave it sitting around while I made all my other chemicals before adding them all together. That was just enough to make nucleation sites that would then grow in unexpected ways.
So I put everything in a metal box during prep time...except I left the lid open. The 11th-hour miracle was just me remembering to close the damn lid.
Yesterday I talked about what happens when things go wrong in your research. It's stressful, but it's not the end of the world. I flamed out of my PhD, but ended up in a good job.
Actually, today I just found out that I will continue to be employed on Monday. Even a good job doesn't always guarantee stability or certainty.
For a lot of people, a science career is a series of short-term, poorly paid tenuous positions. This is true in research and teaching.
I've had a bunch of teaching jobs that paid about what I was earning in grad school. I had a graduate degree, teaching at universities and colleges, and I was as broke as the students I was teaching.
The model at a lot of schools has shifted away from permanent professorship to adjunct or sessional positions. "Let's take a bunch of highly educated professionals and treat them like fast food workers."
This is bad for the professors and bad for the students. Meanwhile there always seem to be plenty of good-paying full-time admin jobs with security and benefits.
If I sound bitter, it's because I am. Since the day I started high school in 1993, I was told "Go to university and you'll get a good job." So I did. And there aren't any. My entire generation is in the same boat.
I was born in early 1980. I'm either the last Gen Xer or the for Millennial. We all took the advice of our elders and went to university, and all the jobs have vanished.
I think I'm getting off topic here.
Since it's my last day here, I want to talk a little about how to communicate your nanoscience. Everyone is telling scientists to do more #scicomm, but nobody is providing any guidance or help on how to do that.
Nobody wants to pay for it, either. It's just one more thing to add to your workload.
I'm going wait a bit, since it's Saturday and I assume everyone is sleeping in. (Not me. I woke up at 6:30 and couldn't get back to sleep. Stupid aging. I miss the days of sleeping in until 11.)
There aren't a lot of jobs for professional science communicators, either. You need to already have a high-profile job, and then do it in your spare time.
Even in dedicated scicomm orgs like science centres, all of the actual scicomm is done by people at the bottom of the pyramid: part-time employees or volunteers. Meanwhile, all the admin staff have permanent jobs and benefits.
This is the same thing that happens in universities. The people who actively perform the work associated with the institute's mission are treated like garbage, while the bureaucracy exists mostly to sustain itself.
@upulie 1. Harrison Ford is the definitive Solo. 2. Because you want to and to hell with what anyone else thinks.
@upulie ...dammit, wrong account.
RT @sciencenotscary: Saturday! After a brief Halloween hiatus, part II of Evolving A Better Eye https://t.co/AXTJ81A9fT #scienceisntscar…
Let me describe my #SciComm credentials.
I am the 2013 winner of the Flame Challenge, awarded by the @AldaCenter for Communicating Science. The center was founded by and named after Alan Alda from M*A*S*H and The West Wing.
The premise of the first Flame Challenge was for actual scientists to explain to actual 11-year-olds what a flame is, because of Alan's dissatisfaction with the answer he got when he asked the question of his teacher when he was 11.
The entries were judged by Grade 5 and 6 classrooms. That was in 2012. After the first year, the kids themselves started picking the questions for the following contests.
The year I entered, the question was What Is Time? This was a little daunting, because I'm a chemist and this is a physics question. Of course, the previous year was a chemistry question and a physicist won.
Anyway, I pressed on regardless and made a little video. It had terrible production values, and it won. This be it: https://t.co/ACzl5kT6Ni
It's just me in front of a horrible orange wall for four minutes. The other two finalists had fancy animations and cartoon dinosaurs, but mine was the only one where the audience could see the person talking to them.
Lesson 1: don't get caught up in bells and whistles if you don't have a clear message. You can do a lot more with simple clarity and charisma than you can with 10 hours in an editing suite.
I spoke in a conversational style, rather that using a stiff, formal lecturing mode of speech. I also aimed it at an 11-year-old audience. It's very easy to get that last bit wrong. Do not aim too low, because that will come off as condescending.
I remember being 11 (dimly), and I always hated it when grownups talked down to me. These kids are on the cusp of their teenage years. You don't need to talk to them like they're toddlers.
I tend to use humour in my videos, because it's impossible for me to not try to be funny. That said, humour isn't mandatory. Being funny isn't as easy as it looks. If you aren't a natural joker, best leave it to the professionals and talented amateurs.
So how do you explain your nanoscience to the uninitiated? The standard comparison is expressing a nanometre in some unfathomable fraction of the width of a human hair.
Thing is, the human mind has a hard time comprehending how big a nanometre is, and saying it's one millionth of a millimetre isn't really all that helpful.
You could say it's bigger than an atom but smaller than a virus, assuming your audience has any sort of conception of the relative sizes of those two things.
When you're not talking to a technical audience, mathematical precision doesn't really matter.
What really matters, and this is true of any scicomm, is to lead with why your audience should care about your work. Why is it important, why is it exciting, how does it matter to them?
Take them through the story of what you did. Even when you're writing for an audience in your field, your article should have a narrative describing the process of your work. The same idea applies outside your field as well.
If you've giving an outreach talk, formal or otherwise, remember to wrap up by recapping the important points you want them to remember.
I never spell a word wrong, I just spell the wrong word right.
It's getting close to the end of Saturday, so I'm going to call it here. I had a good week. Thanks to Pranoti for having me on and arranging this week after week.
@svenja_lohmann @OlgainAus @sciencenotscary [admin] Join us in thanking Steve Maguire (@sciencenotscary) for an amazing week! https://t.co/Ej7kxGbkxC
Clara Barker
@svenja_lohmann @OlgainAus @sciencenotscary [admin] "playing snooker with atoms" please welcome this week's curator Clara Barker (@ClaraMBarker) Oh also, listen to the introductory podcast episode #11: https://t.co/gJ8eZ8Xa48
Hi everyone, @ClaraMBarker here. Really looking forward to a week chatting about science, and also discussing how can we can improve equity to make science for all.
@ClaraMBarker But first things first, it is a Sunday. I don't work on a Sunday and believe that all researchers should take care to maintain a healthy work / life balance. For me, that means hanging out with my little one, Taylor, who is recovering from a long walk around the park earlier. https://t.co/JtutAG3NmU
@ClaraMBarker And swapping my work desk, for my painting desk. I enjoy having hobbies, especially painting miniature figures and watching my fav show, #CriticalRole. Yep. I'm a full on #DnD #nerd and I'm proud to be so. https://t.co/3ShTeklNG0
@ClaraMBarker And with that, I wish you all a relaxing evening and I look forward to chatting to you tomorrow 🙂 🏳️🌈🏳️⚧️
Hi everyone, So welcome to my take over of the channel. My work week is... is all over the place (which suits me perfectly) so I will be sending out tweets when I can. However, I am at my desk, coffee is made so let me introduce myself.
As I've already said, I'm @ClaraMBarker. For those who don't know, I am a thin film synthesis materials scientist, making films by PVD (physical vapour deposition) techniques, particularly magnetron sputtering and PLD (pulsed laser deposition) which I'll explain this week!
@ClaraMBarker I currently manage the Center for Applied Superconductivity, CfAS, at @OxfordMaterials for Profs Susie Speller and Chris Grovenor. Our department is part of @mplsoxford at @UniofOxford. I've been here for 4 1/2 years and it's a lovely group/ department to work for.
@ClaraMBarker @OxfordMaterials @mplsoxford @UniofOxford Our group work with superconductors, particularly high-temperature superconductors https://t.co/auaiSRk7l5. Again, I'll go into this a little more during the week. We also have a number of researchers and equipment working on thin-film battery technology.
@ClaraMBarker @OxfordMaterials @mplsoxford @UniofOxford I've included a snapshot of our main lab, looking at our deposition equipment. There are two magnetron sputtering systems, and two PLD chambers sharing a laser. And yes, I spent a lot of time playing 'lab Tetris' to get it all to fit in' This is the view from my office door 🙂 https://t.co/clTLmBWXoR
Ok, after a bit of playing around trying to return vacuum to one of my systems, I'll give you a bit of a run down of the other part of my work, pushing for euality and diversity in STEMM subjects and doing out reach.
I believe strongly that we should make science for all regardless of gender, race, religion, sexuality, social & economic position, having a disability or being neurodivergent. What should matter is the passion, dedication and talent. Who we choose to be not who we are by birth.
This matters to me because I am some of those things. I am a woman, I am pansexual, I am transgender, I come from a working-class background, I have had to deal with ME and poor mental health for most of my life. So of course, I have a vested interest.
However, I try to also make other people feel that they should have an interest in equality and diversity, even if they don't face these issues. I try and convince them that creating a level playing field for people in academia is actually good for them.
That we can no longer lazily say that who a person is does not influence their scientific career. People are not treated the same depending on their background and this does spill over to who we have working in the labs.
If we are limiting who works in the labs, then we are limiting the creativity and ingenuity that we have in our labs, limiting our ideas. Science is based on ideas. Fresh perspectives and new takes on things. The old cliche is right, we want people who can think outside the box
An atmosphere that pushes people out and excludes it will push out people who may have the 'next big idea' or solve some of our oldest questions.
With that, if we all look the same, our outreach will only bring in more of the same. People will be less inclined to work in a field where they expect they will not fit in. I know this from personal experience.
So this week I will also look at why diversity is good for science and discuss some of the things that I do to try and improve the situation. Although you can get a good taste of my views here: https://t.co/wzSsDvwZ8U
But I am one small part of the puzzle. My perspectives are my own. I have lots of privileges, which mean that I cannot see the big picture. Which is why collaboration and listening to others is so important. One such collaboration is @tigerinstemm (who you'll hear more about)
@tigerinstemm And, as I run to another lab 6 miles away, I will also leave you with a video produced at a @STEMGamechange event that I was part of last year, at the @AlanTuringInsti and run by the amazing @jesswade https://t.co/DuxPMVstm9
Hi everyone, I'm back. And today I plan to talk about thin film deposition. And if I say thin films, what do I mean? Well a thin film is a continuous layer of material that is, for my research, anywhere between a single atomic layer and a few micrometers in thickness.
generally, for me I grow a film to be between 50 nanometers (5*10-6mm) and 2 micrometres (0.002mm), depending on the application. When you consider that a human hair is around to be around 0.05 millimetres thick, I think we can say it is fairly thin. (for me, 0.05mm is huge!)
There are a lot of ways to make a thin film. Most of the techniques I use fall under physical vapour deposition (PVD). These techniques create a vapour of material that coalesces on a substrate material (the material we are growing the film on).
Mostly, PVD techniques grow films under vacuum. I tend to use high vacuum, with a ballpark figure of around 6*10-3 mbar, or 0.6 Pascals (Pa) in SI units. The atmosphere is around 100 kPa and space can be taken as around 1*10−11 Pa.
My vacuum chambers (the box inside which I grow my films) will pump overnight to the range of between 1*10-6 and 1*10-8mbar, depending on the system and vacuum pumps. This is important as is removes air, water and other materials that may contaminate our process from the system.
We need to start at low vacuum as our vapour material can easily react with a residual gasses in the vacuum. For example, if we have an aluminium vapour, it reacts very readily with oxygen to form aluminium oxide. If we want aluminium, then this is not good!
Another benefit of vacuum is that if we have a higher pressure, our vapour will collide with atoms, molecules, etc in our chamber and change direction. When we deposit, we generally want the vapour created to travel to our substrate directly. Collisions may cause it to 'miss'
If playing snooker we want the ball we hit to travel in a specific direction. When it hits another ball, the direction is changed. If this is unintended, our ball misses where we meant to place it such as eg, in a pocket in the snooker table.
The same is true for our vapour which is, basically, atoms, ions and molecules acting as 'balls' and the substrate is the pocket. How we 'strike the ball' and control the angle depends on the technique, and I'll discuss more details in my next batch of tweets!
However I mentioned earlier that for example, aluminium would react with oxygen if it was in our chamber. It may be that we want aluminium oxide (AlOx) so we would introduce (pure) oxygen to the chamber and create an AlOx vapour.
Ok, so I spent far too long making pictures, but hopefully I can explain one of the techniques we use, Pulsed laser deposition. We have two of these systems in our lab, sharing one laser. These are pretty new to us! https://t.co/X1aamFKitt
The laser, an invisible pulse class 4 laser bounces around a long beam path, reflecting off mirrors (and all encased in what looks like a fish tank!) https://t.co/t6oyG2HNbj
Finally, we focus this through a magnifying glass, through a window in our vacuum chamber and by the time it hits our target, the material that we vaporise, it is highly focused and knocks of atoms of the material https://t.co/CbpPoCHW0w
And here are a series of pictures, to visualise the process! https://t.co/3BGEaIRYwG
https://t.co/RnbuPbLtIV
https://t.co/tf6ySi5nGO
Whilst this is happening quickly, and atoms are small, we do see the laser hitting the larget as a flash which I think is pretty cool! https://t.co/uXGZSMF9Y3
[admin] Listen to the episode #11 podcast as @ClaraMBarker candidly explains her research: https://t.co/gJ8eZ8Xa48 https://t.co/C1O8dM9dRB
Ok. So I promised snooker with atoms. This is my main area of expertise. SO how do we turn a vacuum chamber with little inside to something that glows like in the picture? https://t.co/LCr53XVqaZ
We start, similar to PLD. However, this time we have a mangetic field behind the target. https://t.co/p6Y8U7Eni2
We then add a low of argon gas to the system (other gases can be used, but argon is inert and does not react with our vapour) We also apply a large voltage to our target. Electrons are generated in the chamber and some get trapped in the magnetic field behind the target. https://t.co/TakXy85E7c
As argon bounces around the chamber, it may collide with one of the electrons https://t.co/RAS1Hwx0Kd
And when it does, the collision can cause it to loose an electron, becoming an argon ion. The positive charge of the ion is attreacted to the negative voltage behind the target, and thus it is attracted to the target with high energy. https://t.co/Fl0txlhnUl
When the high energy ion hits the target, a cascade collision can happen of the target atoms. Some of these collisions may cause an atom of the target material to be ejcted from the target, travelling through the vacuum. https://t.co/rvxBqJOwXc
Meanwhile, the argon atom may then collide with an electron, recombine and become an atom again. During this time, we are continually pumping the chamber, so some argon will leave the chamber thus we continue to flow the argon in. https://t.co/CF4NxLMSJD
Meanwhile, the target atom may have travelled around the chamber and, if we are lucky, landed on the substrate. https://t.co/pxEgZ7l7gy
Lots of these collisions are happening, so a lot of energy means that we great a plasma discharge, which has a bright glow in the chamber. And the arriving target atoms on the substrate may have enough energy to 'clump' together and form a continous thin film. https://t.co/fenS73nXmF
The plasma is brightest in the area confined by the magnetic field. There are lots of electrons bouncing around this area and some of them have enough energy to cause collisions also leading to target atoms to be ejected! Pictured is a zinc target with an argon atmosphere. https://t.co/iV7bWfXzLm
Depending on the gas used, the target material and the energy of the system, we can change the colour and brightness of the plasma, as different wavelengths of photons are released. Pictured is a titanium taget in an argon and oxygen atomsphere (as i made titania) https://t.co/putKrKA8tR
We can actually measure the individual wavelengths with the right equipment, so we know what we have in the system. With enough collision energy some of the target material may become ions, and this can cause the film to grow in different ways!
And boom, we have played snooker with atoms (and ions!) Of course, it is a little more complicated than described, but it captures the principals 😀 Pictured, a lithium composite target with an argon and nitrogen atomsphere. https://t.co/XJC1nUJgWs https://t.co/3XqDyL9dsA
[admin] Extended podcast out now. Conversation with @ClaraMBarker Epi #12: https://t.co/gJ8eZ8Xa48 https://t.co/FMWHSJCSKT
Morning all. I had hoped to follow up my chat about magnetron sputtering but didn't have the images I wanted to share. So I will continue this now, with a little more in-depth look at sputtering.
Sputtering has various properties that we can control. The pressure, partial pressure of the gas, power to the target, the magnetic fields behind the target, the distance between the substrate and target and more. I'm not sure there is any such thing as a 'controlled experiment'
But we control and fix what we can in order to have usable data. With power, we can actually supply the voltage to the target in different ways. Most common in research is probably DC power, a fixed power to the target. In industry, it can be common to supply the ower as AC
DC is great, it is fairly easy to fix and we can manipulate the makeup of the power, i.e. the voltage and current. However, if a material is not conducive, we run into problems. And sputtering from ceramics is not uncommon (such as using a lithium oxide composite target)
Thus, using an RF power supply is a good way to get around this. You can set an RF offset to the power, or have a net-zero power level. In this way we can sputter materials that otherwise would act as an insulator and prevent us from striking a plasma.
During my PhD and post-doc positions, I made use of an emerging type of power generation, HiPIMS (high power impulse magnetron sputtering). In the technique, we pulse the DC power, having an on-time of 100-200 microseconds, and long off time, in frequencies of 50 - 100 Hz https://t.co/BlWNbKKEmf
This is compared to the frequencies of RF, which is commonly 13.56 kHz and an RMS voltage of zero, or 50 V). As a result, we get duty cycles of around 1%. Which may seem pretty low, but the trade off is that we can generate very high voltages and current during this time. https://t.co/34VnnzXgTS
Note, in the above image the on time is the sharp spike voltage. (The system had grounding issues initially, this the odd offset during the off-time. This was when I started working with HiPIMS, in 2007!)
Having currents of the magnitude of 100 A is not uncommon with associated voltages of 1000 V. Below is a real IV curve that I used frequently during my PhD. Compared to common DC systems, where we use maybe 2 A and 400 V. https://t.co/69nQwG72oW
During my post-docs, I had access to a power supply that could shape these pulses even further. I spent a lot of time 'chopping' the on-pulse of HiPIMS into smaller 'micro-pulses'. I called this c-HiPIMS, chopped HiPIMS, but we still had low duty cycles with long off-times. https://t.co/SjAUQ1K17C
With HiPIMS, we experience a phenomenon called gas rarefaction. The high on-pulses ionise all the gas close to the target, and cause lower partial pressure at the target. Because we use this working gas to cause collisions, we quickly 'run out' of gas and our current drops. https://t.co/YA1fTsHEBO
However, I saw indications that if the time between micro-pulses was long enough, gas was able to refill this area. My indication of this was the peak current of each micro-pulse, where the peak current was much lower for later pulses when the time between them was small https://t.co/XWRtRHsZZd
Of course, this is a balancing act. Once the micro-pulses become too spread out, we can lose the long-off time between the pulse-trains. Once this happens, we lose some benefits for our growing film with these long off-times.
And I'll talk a more about these benefits in my next 'pulse-train' of tweets, finally showing a little of why I spend so much time playing with these conditions 🙂
So, why do we want to play around with the run conditions during sputtering? Well, the vapour, or flux as we tend to call it, of the target material travels to the substrate and grows our think film. However, not all arriving flux is equal!
Depending upon the energy it arrives, and the rate at which it arrives, means that the way the film grows can end up looking very different. In the picture below we have a film grown using DC magnetron sputtering. This is a titanium film, grown to 2 micrometres thickness https://t.co/jfUuKiBi3T
Compared to a film grown using HiPIMS. We have the same pressure, average power and target material, but the additional energy as the flux arrives means that it grows more densely, with fewer spaces between grains. These differences can change the properties of the film we grow. https://t.co/GH9ZBoM4wc
eg in titania films we can change the crystal structure and phases, which in turn can affect the photocatalytic properties of the film. These properties can be used when we create solar cells or self-cleaning glass, so optimising these properties is key https://t.co/LBefvO9Egy
In the paper above, we also highlight the effective heat load at the substrate. Whilst HiPIMS has very high powers, the long off-time means that there is lower average heating of the substrate than with DC, allowing us to deposit on thermally sensitive substrates such as plastics
However, one downside of using HiPIMS compared to DC is that the growth rate, or deposition rate measured as growth in Angstrom/second, A/s, can be significantly lower which can be an issue if you are trying to produce these coatings on an industrial scale https://t.co/17lDqejC87
When using our modified c-HiPIMS, we showed an increase in the deposition rate for the right conditions (different c-HiPIMS conditions are shown in the green line). https://t.co/GEMHGO8gB3
Yet we still had the dense films for these experiments https://t.co/5Mpi6R3A4c. As gas is used to cause cascades, releasing the flux from our target, it makes sense that if we lose gas through rarefaction, as discussed previously, our growth rate drops. c-HiPIMS mitigates this. https://t.co/LnxEvssNWs
As for why we have higher energy, well this can be partially explained by the ratio of ions to atoms of the target material that we release. This starts to get complicated, other people can explain this better. However, more ions at the substrate means higher energy for growth
So whilst DC grows faster, HiPIMS and c-HiPIMS have higher ion to atom ratios, as in the example below for Ti. & remember yesterday I said we can measure the wavelengths in a plasma glow, well we can even differentiate ions and atoms of the same material https://t.co/j57JX3ItaD https://t.co/x86wWCrkLL
Randomly just found a picture of the magnetron deposition rig that I used to get my PhD at @ManMetUni! It had the original design drawings, and they were dated 1979 - the same year I was born! whoever said 'memories of cobbling equipment together' were right! https://t.co/FuoJjFmGuv
@ManMetUni Which makes me want to give my old group, and most importantly my PhD director a shout out. Pete was an amazing supervisor, I was lucky to have him. Without his support, I would not have been able to finish my project due to poor mental health at the time https://t.co/Ysknw2gjeN
@ManMetUni A great supervisor like Prof Pete Kelly important. PhDs are hard work. Having a supervisor who can manage people makes such a difference. We must get away from this 'work all hours' ethic & improve #ResearchCulture as highlighted by the @royalsociety https://t.co/wjJxTujOIX
Hi everyone, busy morning in the lab! Finally, I have some time to tweet'n'eat. I thought I would continue my comments from yesterday, on how we need to improve research culture. Why? Well, because we push people out. Science is not for all: careers are not only judged on merit
Various stats show similar trends, and I'll try and pull out example studies/results to highlight what I say (many from UK studies). Starting with (binary)gender. Despite making up around 50% of the population, women make up a small number of STEM workers https://t.co/VtoHh07dC0
The numbers vary by various factors, such as industry https://t.co/h86vjXCnLe
And some fields are worse than others: https://t.co/L0fKXYFJzr https://t.co/Ti2YltN34y
Generally, it is fair to say, there is a discrepancy, especially in certain fields. https://t.co/PSMBGhw8fx We have an issue. https://t.co/fCejLJFlFp
As of 2018, Nobel Prizes have been awarded to 853 men, 51 women (Marie Curie won it twice) twelve have won the Nobel Prize in Physiology or Medicine five have won the Nobel Prize in Chemistry three have won the Nobel Prize in Physics Why fewer women?
I have seen newspaper headlines just this year suggesting that women don't like STEM subjects, that woman are less good at physics than men. Men seem to have made a lot of the discoveries throughout history - is there something in it? Quite frankly, no.
It is not that long since women have been 'officially allowed' to study science. A quote on the wki for Dorothy Hodgkin says: "where she was one of two girls allowed to study chemistry." https://t.co/GLCBDJO9xu
Cambridge University did not allow women to take degrees until 1947! (It was 1920 in Oxford). If you are not allowed to study, how on earth are we able to make those big discoveries?
Also, if we look to other diversities, BME men are less likely to work in STEM than white men. 62% of black men have suffered discrimination in their STEM workplace because of their race. https://t.co/2R1apWcf03
In the UK, of 14,205 male professors, more than 12,000 are white, while only 90 are black and of 4,735 female (a third the number for males) professors, more than 4,000 are white, while only 25 are black https://t.co/FTLvys0XZW
People with disabilities are 57% less likely to stay in post-grad study https://t.co/2R1apWcf03 https://t.co/KfrQ5G5lbm
And when it comes to LGBTI+ people, sess than 60% of LGBTQ+ people in STEM are out, and again can be very low depending on the field https://t.co/mlyXhc5Un7 https://t.co/qEpbAXx8Pk
1 in 3 US physicists have been advised to stay in the closet (LGBT Climate in Physics, APS March 2016) and LBT students are ~10% less likely to enter STEM subjects, additional to other factors Hughes, Science Advanced 2018)
Is it all bad? Well, we are starting to gather data on these issues. Our learned societies and institutions are acknowledging that there is an issue, and this is a fantastic start. We should not be pushing people out of science because of who they are.
And this does happen. A recent, in depth report by the @RoySocChem @IOPDiversity and @RoyalAstroSoc https://t.co/QFX2ySsuVd showed that LGBT+ scientists often consider leaving their workplace due to the climate https://t.co/ojhln4NJDB
@RoySocChem @IOPDiversity @RoyalAstroSoc If we say that science is for all, how can we reconcile people who are pushed out of their field by the way they are treated. This isn't theoretical, I talk to people all the time who feel this way.
@RoySocChem @IOPDiversity @RoyalAstroSoc I am one of those trans people who did leave. I was looking at new careers and stopped publishing my results, did not apply for fellowships when I should have. I was done. I only applied for my current job to prove a transwoman would not be given the job. Turns out, I was wrong.
A big part of this is having role models. I met 2 LGB scientists in 13 years, no trans ones. I assumed there were no trans scientists because we were unwelcome. Sure, I have faced discrimination but generally I feel very welcome. The idea is we can only be what we see.
Now I know better. There are many amazing groups out there. And having support from others like you is really important. I'll include a few great group accounts I know of: @500womensci @BlackWomenSTEM @500QueerSci @STEMGamechange @PrideinSTEM @tigerinstemm. There are many more!
Science is not for the few. Yes, you have to be smart, hard-working and somewhat apt at science. However, that does not mean you should be excluded because of who you are. It is a right to feel accepted at work.
You don't need to be friends with everyone, but you should not have people who hate you because of who you are, who go out of their way to exclude you.
It is actually good for your groups' output to be diverse too. When everyone can be themselves, they can be creative, work their hardest and will be able to come up with new ideas thanks to a different perspective. Recent reports show there is a benefit to the output of the group
https://t.co/T7tmhj113x and https://t.co/7AZKTYHeFJ https://t.co/roOQIG1I7t
In business, they are starting to see that diversity can improve profit: Business case for diversity: https://t.co/3taC6GB5ZR and https://t.co/rUpYiX6xzA
Of course, we should do it because it is the right thing to do, not because it is profitable for us. But it does help to have extra incentives. A diverse group can lead to diverse ideas, new creativity to solve problems.
And if we really want to say that we have the best minds in science, we need to make sure that is true. If we exclude a whole bunch of people for their sexuality, gender, race etc, then we are lying. We do not have the best minds. We have the best minds of those who fit in.
Hi everyone. I want to talk briefly about outreach and working with young people. For those who don't know, I run a youth organization that has youth groups for LGBTI+ young people. It takes up a lot of my spare time, but it is the most valuable thing I do.
Today I was popped by my core group (and it was a quite session - I blame the weather!) but on a busy week we can have up to 40 young people attend. And we have an awesome bunch of volunteers also, who give up their afternoons and evenings to be there.
I am of the thought that my youth groups are important - that there are a lot of young people that need the support we provide. So I am doing everything I can to provide that.
Normally I would attend for the entire session, but I was asked to speak at a youth conference, delivering a work shop for other youth organizations and run by the amazing Oxfordshire Youth. As usual, there were loads of other amazing youth organisations in attendance.
This workshop was for LGBTI+ inclusion in youth services. I'm so glad that people come to my sessions and they do so because they want their organisations to be more inclusive of all. That they give their time to come and listen, to improve their services
As a youth organisation my success is to become obsolete. I don't want LGBTI+ young people to only be able to come to LGBTI+ groups. I don't run arts or sports groups. I want them to be able to attend groups for the activities, not because it is the only place they feel safe.
Again, that so many people come to my sessions, want to be inclusive of LGBTI+ young people is amazing. And those people running the groups will shape the future, we do shape the minds and values of the people we work with.
So to all my volunteers, my employees, those who I collaborate (and support/guide me) with who attend my training and the young people I do and have worked with - thank you. You are all AMAZING
Continuing with young people, on Wednesday I was part of an outreach event designed to get young women into studying STEM subjects, We went to a school, there was an amazing show (with a pyrotechnic) and then a panel made up of mixed backgrounds and fields.
I think back, and I know I never thought I could be trans and be a scientist. I never had those role models. I never saw people like me in science. Heck, I never saw scientists who were covered in tattoos and for those who know me, I do like my tattoos!
So going out, doing outreach in schools and at festivals or in community / shopping centers is really important. @SoapboxScience and similar projects are really influential. We want people to know that scientists do not have to fit a stereotype, that anyone can be one.
@SoapboxScience The session on Wednesday was part of the (as of Tuesday award winning!) SeeMe project https://t.co/YrZETsEYX0, with @SiemensUKNews @GSAUK , amazing and fiery science show by @Frans_facts and with the wonderful @Sarah_Cosgriff on the panel once again
@SoapboxScience @SiemensUKNews @GSAUK @Frans_facts @Sarah_Cosgriff Outreach is important. To inspire others. And to show that the preconceptions I held for all those years, that I could not be a scientist because of who I am, is wrong. Again, let's make science for all.
And with that, my curation comes to a close. There was lots more I could have talked about but it has also been a busy week. It has been wonderful hearing from people. Please do follow me over at @ClaraMBarker. Thank you everyone who got in touch.
@ClaraMBarker In a few weeks, I will be at another SeeMe event, and also presenting at a conference for LGBT+ inclusion in Academia https://t.co/zRty9Dtv1a which is very exciting. /1192739673891885056?s=20 Thank you so much @MySci_PK for inviting me here, I hope I have done OK!
@ClaraMBarker @MySci_PK And with that, I leave you with a video from Wednesday, with @Frans_facts setting fire to me :) Have a lovely weekend, and I look forward to the coming curs and their stories! https://t.co/zIp8o7zJxP
RT @SeanRCuddy: Science is for everyone. We all work to support people that come after us. We are scientists, role models, and influences.…
@ClaraMBarker [admin] Join in in thanking last week's curator @ClaraMBarker for an amazing week! https://t.co/cCzVRYY7zt
Poornima Peiris
@ClaraMBarker [admin] "let there be light" welcome this week's curator Poornima Peiris @StemCorps Listen to her explain the research in simple words here on episode #13 podcast 🎙️ https://t.co/JilTjfVX3A
RT @StemCorps: Happy to be taking over the @RealSci_Nano account this week to discuss “Catching light at ten to the 9th”& navigating the ju…
@1girl2beakers @Twitch That sounds pretty cool!!
A little sneak peek of our lab’s work: light propagation in the Nano scale with the use of specialized Nanowires & nanodots @FrontNanotech @nht_lab @NanobiotechRMIT @SNIunibas @AusNano @NanoMed_UNSW @NanotechNyc @Nanotechnology @WomenInOptics @4womeninscience @WomenSciAUST https://t.co/aFml7GFr85
Nano materials display light absorption properties and tuning of these optical properties can lead to applications in narrow band filtering, spectroscopy and multi spectral imaging. @theSTEMsquad @thoughtsofaphd @herstemstory @HerSTEMCareer @WOCinSTEMChat https://t.co/mT054QaO5m
More info on this: https://t.co/R0yKK5hQbo
#womencrushwednesday Need I say more, she was one of the first to use lasers for magneto-optics experiments. @WomenInOptics @WomenInPhys @womentechspace @MinoritySTEM @4womeninscience @WomenInSTEMAu @theSTEMsquad @OWSD_SA @spiffyscientist @LGBTSTEM @STEMGemsBook @scienceinpublic https://t.co/7VJtVmFjOQ
Which also led her into the field of Raman spectroscopy. Here’s one of her papers on the subject! @WOCinSTEMChat @goldieblox @ETH_physics @PhysicsVideo_ @UoMGraphene @Graphene3D @GreenNanoRes @NanomaterialsJ @RealSciMods @MarionPtG @OmicsScience @SidewalkSciGuy @DishPodcast https://t.co/0vTiWAqcbT
Raman spectroscopy is a light scattering technique, as demonstrated above and interacts with a photon of light to produce radiation at different wavelengths.
[admin] "let there be light" extended podcast with this week's curator - Poornima Peiris @StemCorps, out now. Listen to her explain the research in simple words here on episode #14 podcast 🎙️ https://t.co/JilTjfVX3A
RT @StemCorps: My 1st podcast, extended version, sniffles included lol @Zuber_Kamil @4womeninscience @tigerinstemm @rachel_grange @Plasmon…
Check out the importance of nanoscience research @MinoritySTEM @dailystem @ACS_ANM @FrontNanotech @NanotechNyc @Quandu @NanobiotechRMIT @CU_WIC @WomeninTechChat https://t.co/luFjCQl4Bg
What are some of your fav Nano papers? here’s an interesting one @FrontNanotech @WomenInNanosci @WomenInOptics @SNIunibas @ACS_ANM @EUNanoSafety @FrontNanotech @willaonthego @sciencenotscary @scienceinpublic @iamscicomm @NanoLightLab @NanowireUK @smoremagzine @theSTEMsquad https://t.co/Ocgo80fK2y
#confession Guys, as a first gen student in STEM, finding my way in stem was hard as I had to be my own mentor most of the time, and then finding the right mentors was a journey in itself, to see if they had your best interest at heart 💙 @WOCScan @TheSocScientist
RT @StemCorps: #scicommsaturday What are your stem #confessions? @WomenInOptics @4womeninscience @SciSwany @MeTooSTEM @Lotus_STEMM @SpaceAr…
@StemCorps [admin] Join us in thanking Poornima Peiris (@StemCorps) 2 podcasts and blogpost: https://t.co/JilTjfVX3A
Matthew Diasio
@StemCorps [admin] "graphene smoothie" - please welcome this week's curator Matthew Diasio (@MatSciMatt) 🎙️ more info here: https://t.co/Bl59fITFc7
RT @StemCorps: It was a pleasure curating the real nano sci account this week and sharing my first podcast with you all 💙🙈hope y’all learn…
Hello everyone, My name is Matthew and I'm very excited to be curating for RealSciNano this week! I just defended my PhD dissertation at @UVAEngineers in materials science. My work focuses on making graphene and a lot of different parts of rheology.
@UVAEngineers I suppose if you want to know what all of this week will be about, you could skip ahead and read my dissertation hot off the cyber-presses: https://t.co/mOdcpMDGTO But also that might be a lot. So let me do a brief introduction about me instead.
I did my undergrad in #physics, initially wanting to go into astronomy, but got really interested in #nano after a chemistry seminar and awesome summer projects on nanotubes. Outside of lab, I'm active in #SciComm, #SciPol, and student gov't. Also fall in Virginia is beautiful!
Happy Monday everyone! Today I'm going to be giving an overview of my #nano #materials work on "graphene smoothies". https://t.co/44tE4ZkwYl
So what is graphene? You may have heard about it in the news... https://t.co/NbgUZU9FSK
Graphene is one of the many forms ("allotropes" if you want a fancy chemistry word) pure carbon can take. In fact, this image shows 8 allotropes of carbon. https://t.co/bK5SCrQ0Es
The top left and top center show the forms we're most familiar with in our normal macroscopic lives - the top left is how carbon is arranged in diamond, and the top center is graphite.
And if you look closely at graphite, you can see that it is made up of pretty distinct layers of atoms. The carbons are all covalently bonded (the kind where atoms share electrons) to other atoms in the same layer. These individual layers are graphene! https://t.co/M4GqpYLrhb
At first, this was just theoretical. Physicists were referring to the graphene layers within graphite since around the 1950s, as a useful concept and shorthand.
But in 2004, researchers not only showed that they could isolate a single layer of graphene in real life, they were able to characterize its properties. And that was so impressive they won the Nobel prize just a few years later in 2010.
I have to take a break for a meeting, but more graphene fun facts will be coming later today! https://t.co/j7MDNA1NvY
As a bit of an aside, it turns out carbon has tons of allotropes. There's now a database dedicated to tracking them all to improve consistency, and it lists over 500! https://t.co/yh2Wle4oQy
And new ones still have surprising properties. "U-carbon" was just announced and may be ferromagnetic at room temperature, which has never been seen in other carbon allotropes. https://t.co/3GyOGELnIa
Carbon is like the Meryl Streep of elements: You can try it in any role at least once. (Though it may not always be as great as Meryl Streep) https://t.co/DCqmMaQHGq
RT @svenja_lohmann: Moving to 2D materials (e.g. graphene) now allows to study what happens IN the surface only! #IISC23
Outside of work, I'm really involved with @scipolnetwork! Tonight, the Communications Committee is having its monthly meeting. Shout-outs to @CaitlinAShort,@VivaceBelles, @_sindhu42, @MeredithSchmehl https://t.co/hjAHuMwgTd
@VivaceBelles @scipolnetwork I feel like every photo I ever take in a webcam looks like I'm tired or perplexed.
Good afternoon everyone! I want to pick up where I left off yesterday discussing graphene, and this will be a good segway to talking about colloids today! GIF below: also a good segway https://t.co/qmDoh7TPeZ
As I mentioned, "graphene" is what we call an individual layer of carbon atoms in graphite, and the image below shows the crystal structure of 3 layers in graphite. https://t.co/1VrHJN9crD
So how do we get an individual layer (or in technical terms, a monolayer)? I mentioned that a group managed to isolate monolayer graphene in 2004, and characterize it well enough to discover its properties.
This actually surprised some people, b/c while physicists had theoretically discussed graphene for decades, several thought it was impossible for a free-standing, single atom thick material to be stable on practical time scales.
For those interested in history #HistSci #HistSTS, this leads to some neat discussion about who "discovered" graphene. One of the graphene laureates, Andre Geim, has written on the "pre-history" of graphene before 2004 (unfortunately, this is paywalled https://t.co/xvOYuT8ch0 )
Andre Geim and Konstantin Novoselov actually used Scotch tape in their Nobel-winning work. They donated their tape dispenser, some graphite, and a graphene transistor to the Nobel museum! https://t.co/aL73UDUBgr
Here you can show the "Scotch tape method" being demonstrated by researchers in their lab: https://t.co/tiKnJEffJa
Also, don't Google "Scotch tape method" without mentioning graphite or graphene, otherwise you might end up finding really gross things about tapeworms you weren't expecting to learn. Or at least that happened to me a few years when I was working on my lit review.
You can also see in the graphene Scotch tape video that you can't really make a lot at a time. It's great for research - it makes high-quality material to test out new devices. But it's now how we're going to mass produce graphene to make the wonder products of the future. https://t.co/vGb2DJQlI4
Also, you might be wondering why we even want graphene. That's a good question! It turns out to be a really impressive material and illustrates some neat concepts in nano and materials science when you compare it to graphite. https://t.co/YbR3CqFKTY
For instance, graphene is the strongest material humans have discovered (~100x stronger than steel). And you might think that's wild because we use graphite to write because it's so easy to break off pieces. But the difference is what's under stress.
The bonds between carbon atoms in the graphene plane are incredibly strong (stronger than diamond!). When we're breaking up graphite, you're breaking it up between layers, and those bonds are very weak.
Graphene's also really conductive, but even more impressive is its "mobility" - how fast the electrons carrying charge move - which is 100 times faster than that of electrons or holes in silicon (e.g. our current computer chips).
While graphite is reasonably conductive, it's not as impressive because it turns out even the weak bonds between graphene layers disrupt this electron motion.
So with those superlative properties, we want to use graphene for a lot of things: https://t.co/A4OwlEoj0b Sometimes we want to use graphene straight-up, but we can also add graphene to other materials to improve their properties! https://t.co/uSSFkLam0d
For instance, adding less than 0.1 percent (by weight) of graphene to the plastic PET (which you may know as Dacron or Terylene) increased its strength by 40% Source: https://t.co/wNGLRMIgsu https://t.co/kCgSTrKMo9
@StemCorps @MatSciMatt [admin] "graphene smoothie" podcast episode #16, conversation with @MatSciMatt is out now. find it here: https://t.co/Bl59fITFc7
That's a good question! The Fermi velocity of electrons in graphene is about 0.3% the speed of light, so the Lorentz factor is still really small and you don't see much change in relativistic mass. https://t.co/ds69GGWo7x
But, it turns out the honeycomb lattice of identical atoms leads to an interesting property. The dispersion relation between electron energy and momentum is linear, so the conduction electrons actually behave like they have zero mass in graphene!
When people say electrons behave like light in graphene, that's the linear dispersion relationship More formally, they're described by the Dirac equation as massless particles (but the speed of light needs to be replaced by their Fermi velocity).
It turns out this works in other lattices with identical molecules. For instance, a lab at Stanford made "molecular graphene" by making a honeycomb of carbon monoxide molecules on a surface, and the electrons behaved similarly https://t.co/DExCHqPzkO https://t.co/3gpyEs7W51
Continuing last night's discussion, what’s cool about graphene is that you can make it both starting from graphite (a “top-down” method), like with Scotch tape, or in a “bottom-up” process where you bring together carbon atoms. Image source: https://t.co/XXal860uvQ https://t.co/q1rtjmOUv6
Check out this thread from last night on why scientists and engineers really want to use graphene! https://t.co/mMxkXWz0Pu
The application you want graphene for is often a good guideline for how you should make it. Do you want it for electronic devices? Then you need consistent sizes and very few imperfections. Bottom-up processes enable more control over the quality. https://t.co/eTsMGvUy9p
Do you want a lot of graphene, like to use as a filler in composites? Then you need to mass produce it, and only the top-down processes scale up. You lose some quality control, but a well-characterized distribution of sizes can be useful in these apps.
While the Scotch tape method is a top-down technique, the techniques that will probably be used to manufacture graphene on large scales use liquids to break down graphite. The two popular ones are (1) sonication and (2) shear exfoliation.
Sonication uses sound to make a micro-bubble bath. If you’ve seen a cleaning bath for glasses or jewelry, they’re a kind of sonicator. https://t.co/pbAq1HrE18
Sonicators use sound waves to create small bubbles in the liquid, and when these collapse, they generate intense pressure and shock waves that break apart the graphite. Image source: https://t.co/VfQM1eh0vT https://t.co/c9wXGIG541
It’s a bit harder to scale up sonication than first glance might suggest. Most of the sound energy gets absorbed close to the moving surface/tip, so adding more liquid doesn’t really change the working volume. Scaling up the volume requires adding power.
And those collapsing bubbles are really violent. They heat the surrounding area to a few thousand degrees C at rates of billions of degrees per second! The shock wave also creates pressures >1000 atmospheres! This turns out to make new defects in the graphene.
So instead of blowing apart graphite to make graphene, why don’t we take a clue from our pencils, and peel layers off? https://t.co/WtLp3co0IX
This is where the "graphene smoothie" comes in. In 2014, a group made graphene in a blender. First, they did try it in an industrial blender, but then they found they could make graphene even in a kitchen blender! https://t.co/j46GEXOwmu
In the blender, the motion of the liquid peels layers of graphene off each other. https://t.co/KRYHQMtKgl
The peeling is driven by the shear forces in the liquid. The slightly different speeds of adjacent flow can slide the graphene layers relative to each other. https://t.co/EMgXwd9ZTF
The #graphene in a blender paper was HUGE for the community, because it showed several improvements over sonication.
(1) It takes less energy to slide graphene layers off each other instead of pulling/blasting them apart from the bubble shock waves.
(2) This less violent sliding process doesn't create new defects while you're peeling off the graphene.
(3) Blending scales up better than sonication. Production in sonication is almost directly proportional to power. In the blender, it scales up with the liquid "smoothie" volume without requiring the same increase in power.
And sometimes at the end of blending graphene, you can see some flakes that were still in the middle of sliding off each other. Image source: https://t.co/wNGLRMIgsu https://t.co/8QRftHQotO
@StemCorps I've heard carbon nanotubes are used in rackets for a while, but I haven't heard much about graphene. There was a neat study of an alleged graphene racket, showing that the material was mainly carbon fiber with some graphite nanoplatelets. https://t.co/qplhqsf1cl
RT @StemCorps: @RealSci_Nano They use it in building tennis rackets as well if I’m correct?
RT @RealSci_Nano: @StemCorps I've heard carbon nanotubes are used in rackets for a while, but I haven't heard much about graphene. There wa…
The early blender #Graphene work is based on mixing the graphite in a liquid that has a similar surface energy. If they have the same surface energy, you don't need to add energy to make more interfaces going from a hunk of graphite to individual graphene flakes. https://t.co/Gw9YmzpjMx
This graph shows how the graphene concentration changes as a function of the liquid's surface energy/tension (they're related values). Image source: https://t.co/h6mYeoLhq3 https://t.co/RiHJZcOhd8
The peak around 70 mJ/sq. m reflects graphite's surface energy. But you also see that there's some spread in these values. Also, it doesn't really predict how stable the isolated graphene is in the liquid against clumping back together into graphite.
So then work started to move on from surface energy to solubility parameters. In chemistry class, you learn that "like dissolves like". Solubility parameters are a way to quantify that to help make more rigorous predictions.
In graphene work, it's popular to look at Hansen solublity parameters - one parameter for each of 3 important aspects in chemical bonding. (1) London dispersion (when random electron motions cause attraction) (2) the force caused by permanent dipole moments (3) hydrogen bonding
We can think of these as making a 3D Hansen space where each liquid and solid can be plotted based on their values. This graph shows the solubility of nanotubes (shown by sphere size) at the Hansen point of several liquids. Image source: https://t.co/2h6ncZA6Nb https://t.co/lv3KEUt7ja
We just hit 300 followers today! Thank you everyone! It's exciting to spread the word about #nano and #materials #SciComm. https://t.co/VpedbWQMPA
You can also think of how "like" two substances as being related to their distance in Hansen parameter space!
Although even using the more detailed parameters doesn't explain all the data we see in the field. This is a graph showing how much graphene is made in different liquids based on how far apart they are in Hansen space. Image adapted from https://t.co/OygEXFMAxi https://t.co/mD5XznAO0y
By definition, solvents at the same distance in Hansen space from graphene should be able to disperse the same amount of material. But you can see that's not true, especially when you get REALLY close to graphene's parameters.
@StemCorps It's also confusing because there are definitely a number of products that claim to include nanoparticles, but actually don't. @TheWilsonCenter has an inventory trying to track and verify various products touting nanomaterials. https://t.co/ILRfCTfnoj
RT @ProfArmani: The #photonics community is taking radical action w/ @PhotonicsMeetup led by @r1cc4rd0, @igordownunder, @Orad, @rachel_gran…
RT @cshperspectives: Where are bioRxiv preprints finally published? https://t.co/wNsnb58ItD
So now I'm going to be talking about where I came in on the #graphene blender field and my dissertation, so I guess this is a very literal #PhDChat.
Last night I mentioned that even the more detailed Hansen parameter framework doesn't explain all the variations seen made by blending graphite into graphene in various liquids. So what other physical properties could matter?
If you look at the way the liquid moves, the sliding is driven by the shear force between the layers of fluid. The force is the product of the shear rate, that gradient du/dy in velocity between layers, and the viscosity η. https://t.co/NQgq2D0Ir6
Viscosity is the technical term for what we often call the “thickness” of a liquid. A “thick” liquid like honey is more viscous than a “thin” liquid like water. Or I suppose blood is metaphorically more viscous than water.
If you increase the viscosity at the same shear rate, you increase the force. My big hypothesis for my dissertation was that a more viscous liquid could help you exfoliate more graphene. And, yes exfoliate in the sense of a skin care routine, b/c both are peeling off layers. https://t.co/RkxCFIuwAu
So I tried blending graphene in 3 solvents with different viscosities. 1) NMP, the common solvent used for graphene, with a viscosity like water 2) Benzyl benzoate, about 5x more viscous 3) Propylene glycol, about 25x more viscous
However, I didn’t use a kitchen blender to test this. I used a “rheometer”, an instrument that let me precisely control the flow of graphite-liquid mixture at multiple shear rates, so the flow was identical for all three solvents.
After centrifuging out the graphite that didn’t break up, I measured the absorbance of these dispersions of graphene in liquid, which is roughly proportional to the amount of material at low concentrations. (Thanks Beer-Lambert Law!)
You can see that at every shear rate, the most viscous PG is more absorbent than the least viscous NMP, which is a sign of more graphene being made and which confirmed my hypothesis! https://t.co/RIyQCjBgsJ
You might be curious about the BB/Benzyl Benzoate, which has an intermediate viscosity but does the worst. It has a very different dielectric value from the others, which we think increases the van der Waals forces between graphene flakes.
Based on the fact that BB doesn’t even seem to consistently follow a trend within itself of greater absorbance at higher shear rates, we think the flakes are clumping back together into graphite so fast it was unstable by the time I tried measuring it.
If you’re really interested in these tweets, they are based on my first published paper, over at @Materials_MRS https://t.co/QzBOEPaxkg
Also, excitingly, this trend help up in a real industrial mixer! https://t.co/gPdfDnkUAG
Here's what it looks like when I make the "graphene smoothie" in the industrial high-shear. I start with graphite mixed in with the liquid, at a concentration of 50 grams of graphite per liter. https://t.co/T7ytvSdwfv
I don't really see much of a change before and after mixing. A concentrated graphite dispersion looks pretty similar to a concentrated graphite/graphene dispersion to the naked eye. https://t.co/GZ4wDk4QqL
Also, even with the graphite, these mixtures are still pretty thin, so I've never been able to pull off some graphite-based #LatteArt as #SciArt. https://t.co/ftMpixmj8j
However, while this may not be the prettiest #SciArt image, I am really proud of this electron micrograph of my #graphene. There's so many neat things here! https://t.co/kZiT8USNCm
These central flakes show outlines that are slightly displaced from each other. This shows they were still sliding off, just like that one from the original blender graphene paper! https://t.co/z0HlV9NNNp
And in the center here is what looks like true monolayer graphene, based on the lack of other edges or wrinkles! (A lot of blender graphene is actually few-layer material, say 2-5, but if you can produce a significant of monolayer, that's great.) https://t.co/rB3Fo1cQDT
Oh, I meant to add, this image is from the propylene glycol mixture, so I found out this new solvent not only can make more graphene than NMP, but the graphene it makes it of similar quality! More bang for your buck, if you will.
A study just came out about the importance of #nano #materials for new #energy storage technologies to address #ClimateChange #ClimateCrisis https://t.co/jcDwuPeRmy
So as part of my PhD #WorkLifeBalance, I've spending Thursday nights this year boardgaming with friends, so I won't be around for much of tonight. But I would love to take questions from people that I can answer for my last two days as a curator!
The original inspiration for my dissertation was to add the graphene into polymers, which tied into my graduate lab’s study of “soft matter”. What is soft matter? Literally stuff that is soft, for the most part. Or as we say in my department, the stuff that is “squishy”.
RT @realscientists: When talking about squishy materials, I often ask people if they like to cook. Because I think understanding cooking ca…
I talked a lot about squishy materials when I got to curate partner account @RealScientists earlier this year, so let me share some highlights from there. https://t.co/YpcytLy2RY
Most foods, except hard candy, are soft matter: https://t.co/niBrl4eW9z
Soft matter is everywhere! Other things you may have interacted with today that are engineered soft materials: lotions, make-up, ink. You might just think these are liquids, but they’re behavior is more complicated than something just like water or even a simple solution.
Also, for another name that describes exactly what these are, we call these systems "complex fluids". Or you can also call them #colloids, which you might remember from a #chemistry class.
What's a #colloid? That's a great question! It's a mixture where microscopic particles of one (or more) chemical are uniformly mixed (dispersed) in another chemical (the dispersing phase), but these chemicals still exist as distinct phases.
So sugar water is a solution - the sugar is broken up into its molecules, which each get surrounded by water molecules. (The sugar is "solvated"). But milk is an emulsion - a colloid of two insoluble liquids, in this case the milk fats and water.
Or maybe I should just say modern milk is an emulsion. Cream would rise to the top of milk before homogenization because it wasn't a stable mixture. Homogenizing breaks up the fat into much smaller particles that are more stably mixed into the water. https://t.co/w31LEA9b9w
This lovely table from Wikipedia classifies all the various colloid phases you get by mixing solids, liquids, and gases. https://t.co/q13CK5y9P0
This may also answer your childhood questions of "is dough/Jello a solid or a liquid?". It turns out they're both. Jell-o is a gel, liquid dispersed in a solid. Raw dough is also a gel, but bread is a foam. https://t.co/B5XGhOOaSS
You also may have noticed I spent most of this week using the term "dispersion" or mixture to describe my #graphene-in-liquid system. That's because it is a colloid - the liquids aren't breaking up the graphene into its constituent carbon atoms like in a solution.
This is also why the electric properties of the liquids matter. Since the van der Waals force is a major force for colloidal particles, we can tune that through the difference in dielectric between the particles and the liquid.
Also, following up on this, a new favorite paper I've seen actually tries to add #graphene into polymers by adopting the pressing and folding method from making croissants! https://t.co/lWIrMyusRT https://t.co/niBrl4eW9z https://t.co/fAR3Oe56si
A vinaigrette is one way to understand composites, but for the graphene, it’s helpful to consider another food analogy https://t.co/guAYsmfb9v
When you want to mix a really hard, compact material like graphene with wobbly polymer chains, I like to think of this like making fettuccine alfredo, but the American kind, with the extra toppings. https://t.co/an1aTA17YL
So have ever eaten a bowl of fettucine alfredo only to find out at the end that all the chicken and broccoli fell to the bottom instead of mixing with the noodles? The noodles entangle with each other, not with the stiff edges of the toppings. This is a problem with polymers too!
If you added chains to the surface of the topping (or filler), they could get tangled in the big mess of noodle/polymer chains and they would be strongly mixed together. Well, we're not going to do that for chicken alfredo. But you can do this for nanoparticles in plastic. https://t.co/wXMi9Dto3D
This prevents them from separating out and makes sure they reinforce the whole material.
To finish out my week, I'd like to briefly discuss #rheology, or the study of flow, which is very useful for understand squishy materials.
I wrote this up two years, after I proposed my dissertation, and I think it's a fun piece. For instance, I learned that rheology may in fact be related to Rhea Perlman. https://t.co/LV3Y14B9Ue https://t.co/sjozLidloY
I mentioned my lab's rheometer earlier this week, but didn't describe it much besides saying it enabled precise control of the flow of my graphite mixtures. Here's what it looks like in action! This the set-up I used to break down graphite into #graphene. https://t.co/2PcmSZuGaX
This is essentially two slightly differently sized concentric cylinders, and the inner one rotates at speeds to apply the shear force or shear rate I want. This geometry is really nice because it prevents turbulence, which simplifies the experiment https://t.co/bjazX29FRq
And here's a video. This geometry is also useful for me because it lets me apply a very high force to low viscosity colloids. https://t.co/psL4vNlIGD
Here's a different geometry, with a cone and a flat plate. For really small angles α, the shear force is uniform for the whole sample. This set-up is useful for studying very viscous materials. I was using it to study when the graphite-liquid mixture became gel-like. https://t.co/Z7VHpJYt50
When you're studying soft/squishy materials, you learn that many don't have a single viscosity and that they're "non-Newtonian fluids". This means they're viscosity depends on the stress being applied and/or the history of that stress over time.
Many polymer mixtures are shear thinning - they get less viscous as more stress in applied. This is because the chains will first start to untangle from each other, and then they start to line up with each other, making it easier to move. https://t.co/l4piPynTks
Ketchup is (in)famously "thixotropic". When you agitate a thixotropic material, you disrupt the bonds between molecules and becomes weaker, but it will start to recover over time. This is why you often need to tap a ketchup bottle to start pouring it out.
And "oobleck", that fun mixture of cornstarch and water, is shear-thickening - it actually becomes more viscous under stress. https://t.co/gGVOYlGPsu
Why is oobleck shear-thickening? Good question! We're still not completely sure. A study published just last month seems to have come very close, suggesting that higher shear rates cause the particles to lose the lubrication between them. https://t.co/6IhxEf7xm5
I now want to shift gears in my last few hours curating and talk a bit about #SciPol (science policy) and some #PhDchat about life in grad school.
I want to share this thread I wrote on the news about a toxic and abusive lab environment. https://t.co/mynQIP3vk1
@StemCorps Oh no, I hadn't considered that. It's from the local newspaper in Madison, WI, and some of those sites don't do GDPR. Here's an Inside Higher Ed article on the same lab. https://t.co/z8ELVOQD5X
A common thread from stories like this and even studies on #PhD #MentalHealth is that schools don't really formally track the experiences of their grad students https://t.co/SEBFxfdRm4
In graduate school, I have (was? I'm not used to this being past tense yet) involved in groups like @uva_gpc and other graduate student government to help advocate for policies to improve our working environment and lives.
@UVA_GPC Groups like @uva_gpc, @NAGPS, @SPIatUVA, and @scipolnetwork were vital to my success in graduate school, because they let me learn about what goes on in other programs and other schools.
@UVA_GPC @NAGPS @SPIatUVA @scipolnetwork It's really easy for an abusive advisor (or an entire program!) to just kind of continue going on because it seems like most schools really don't do much tracking of what happens to grad students between matriculating and leaving (whether that's graduation or being forced out)
Important institutions in #SciPol are also reacting to these concerns about poor student experiences in graduate school. Last year @theNASEM published a report on improving graduate #STEM education https://t.co/pp3SEp9wkb
A current @theNASEM project is looking at mental health of students in STEM fields https://t.co/Gc9i4Rro3S
I wish I had more time to spend time to also talk about these important developments, but I will need to go soon. You can find me tweeting about grad life, #SciPol, and #SciComm on my personal account @MatSciMatt
I was hoping to tweet more about these important issues, but I also am still feeling that post-dissertation bliss and wanted to share all my research with you now that everything has come together and there's only so much time.
I hope you all enjoyed this week on #graphene, colloids, and #squishy materials. I had a lot of fun! Thank you @MySci_PK for creating this account and this opportunity!
@StemCorps @MatSciMatt [admin] Join us in thanking last week's curator Matthew Diasio (@MatSciMatt) for the amazing week about "graphene smoothie" and more. 😉 podcasts and more here: https://t.co/Bl59fITFc7
Thorsten Feichtner
@StemCorps @MatSciMatt [admin] "Squeezing light with nanoantennas" - please welcome this week's curator Thorsten Feichtner (@ThFeichtner) Podcast and more info here: https://t.co/P7lMuLKGOu
Good evening, everybody. It's my pleasure to curate the @RealSci_Nano for the next week. So I start with something private before explaining the beauty of optical antennas. Take a look at my profile pic. There in the background is my 5yr daughter 1/2
The mismatch in gender equality is a big topic and has been tackled here also by some wonderful people. I witness already now the origins. There is a culture which is nearly impossible to fight in already in the kindergarden. I fight against it by offering options. 2/3 (!)
I'm a LARPer, a live role play gamer by heart (more at the end of the week ;) ). I'm proud, when my daughter want's to wear the leather armor I built for her despite the fairy costume. And I offer her the @kiwico_inc boxes and she loves them. That's my way to equalize culture. https://t.co/813GnMsQEG
Good morning! I start with a question: what is an antenna? Seems simple? Then maybe you might think about this: Is a Stone applied for tucking a nail into a wall already a hammer?
We are used to define a thing by its shape instead of a function. So for a long time an antenna looked like this. That is a dipole and its length corresponds to half of the electromagnetic wavelength it should work with. https://t.co/9KsM4VDkud
So light is an em wave, too, and the straight forward idea is to scale things down which in principle works. Here you see the dimensions and the currents in such an antenna. https://t.co/Cw0bubZyr8
And here comes the fancy thing! If you look now at the fields in the gap of the metallic nano rods comprising the antenna you have squeezed light!!! Red light with a wavelength of 800 nm can normally just focused down to about a 400 nm spot. now look here at the top graph. https://t.co/VByeSE8fG9
the light intensity in the gap is more than 4000 times higher that of the optimal focus by means of mirrors or lenses. An the volume is about 20x20x20m³. That is squeezing of light!
Finally, how did I get into my topic? Just by chance.😁 I studied physics to save the climate, to solve the energy problem by making plasma reactors functioning (GIF). I chose the "wrong" university due to family/friends reasons. I did a good old diploma and needed a topic ... https://t.co/FOZYSZw93A
By the time I had a girl friend studying computer science so I wanted to stay in the "wrong" university, which is the @Uni_WUE to finally tell it. I found a position with Bert Hecht who just started to build his new group "Nanooptics and biophotonics". I stayed for the PhD.
@Uni_WUE The girl friend became my wife and started her PhD at the @FraunhoferIIS in Erlangen and I managed to solve the academic two-body problem for a while and hired successfully at the @MPI_Light. Two years later we had a three body problem to solve when my boss moved to @HZBde.
Computer Scientists can work a lot from the home office and so we started a 14 month journey to Potsdam. However live is rarely predictable and we moved back. Now we are located quite in the middle of Erlangen and Würzburg and commute a lot of spare time away 🥴
I later took a job as managing director of the cluster of excellence @ct_qmat due to curiosity and to get a save position within academia. However, things are changing again, as I will start a @MSCActions ind. fellowship in May '20 at @fisipolimi with @pbiagio78 and @vynisle 🥳
And now you know, how lucky and happy I am at the moment. Sleep well and tomorrow there will be some more science!
Good morning everybody! Today we are live from Hannover where @VolkswagenSt hosts the Forum Experiment! I'm one of the last years grantees and together with my PhD student Luka Zurak we show a poster of a high risk project. https://t.co/luZlA1ECWG
Fun or not? Half of the grantees where chosen by a lottery. So I don't know, if my idea was compelling or me just lucky. But I really like the idea to grant some research money by chance. Science itself is often a game of luck, so why not also funding? 🎲🎲
Now back to topic first. What can you use an optical antenna for? I start here with a small poster I did a few years ago, which is not complete, but an overwhelming start to get the ideas rolling. https://t.co/uLNRrLiGtm
There is often an argument about heat generation in metallic nano particles showing plasmonic resonances. Some say it prohibits applications other say it opens applications. Both are right in my opinion. Here my high risk project idea to make use of the heat @VolkswagenSt .
https://t.co/CxhQWpbo4K
Nano particles to defeat funghi in wine plants. Super useful nano research at the Forum Experiment! @VolkswagenSt #ForumExperiment2019 https://t.co/CQ7onPNLSx
My PhD student Luka Zurak at his 2 two minute lightning talk. Did a good job. 🙂 @VolkswagenSt https://t.co/n0xRFKLTD1
The next nice and exotic nano topic: can a network of electrospun magnetic fibres function like a brain? https://t.co/yDCzNhUbBs
Answer: it is difficult 😉
Good morning! So yesterday was difficult for me to keep you informed continuously due to conference dinner and the first Christmas market of the year. Picking up again today :) https://t.co/xwRbRfDXZB
So I do a smooth transition between the topics application and fabrication: We can realize waveguides utilizing plasmons to squeeze light in 20 nm air gaps between two thin gold bars. To efficiently couple the light in, we need an antenna. Two examples here - choose your favorite https://t.co/WsabNpjIK6
Of course, everyone who wants no scattering will choose right: smooth geometries at the nano scale! The left picture originates from sputtered gold as thin layer (how to structure: afternoon) the right one needs the introduction of our irreplaceable basic material: gold flakes! https://t.co/ndH5z8QzcE
Short excursion into chemistry: Here is the old recipe (https://t.co/sh2PRbFrjU) which we did not invent, but discovered for plasmonics. It is a wet chemical process. All the crystals can here grow for themselves contrary to the standard process, where they meet after 30 nm. https://t.co/1C0c2idy9u
In the old days it was believed that the aniline is important. No. The platelets also grow without, if they get the time to do so. The mechanism behind this greatly inhomogeneous growth is still in debate, but here is a hint: there are always a few stacking faults. https://t.co/oAjz7SZW4x
Short intermediate apology: twitter is too short to define all scale bars 😅
@StemCorps @MatSciMatt @ThFeichtner [admin] "Squeezing light with nanoantennas" - extended podcast out now! in conversation with Thorsten Feichtner (@ThFeichtner) - https://t.co/P7lMuLKGOu
Good evening. Here a sketch of all physical processes happening while our favorite structuring technique: focused ion beam milling. We really only want the sputtering, the rest is annoying, but scarce enough to still yield beautiful nano antennas. https://t.co/P5IvShdwmN
Picture created by me, Inkscape is just awesome. Feel free to use. I'm anyhow a freeware and Linux fan and user .. most of the time. Just our administration forces me to still use MS products 😤
Okay, this was a long silence, and I would be much happier, if it was due to a long and successful measurement of a quantum dot illuminated with our inverted confocal microscope while AFM-scanning an antenna over it. Yes, we do this here at the EP5 in Würzburg. But not me. https://t.co/AcZPJ7sadv
Despite meetings and their prep. I have also a favorite machine: Since Feb. we own one of the most exciting structuring tools for nano technology: A helium ion microscope. Look at the testpattern SEMs: Gallium is left and to use for rough preparations and Helium right. Neat! https://t.co/yKArQwcUyj
There are many way to solve Maxwells-Equations on a computer, but, I'm still impressed by FDTD, solving E- and B-fields just interweaved in space and time! Here is a Yee-Cell, the basic space element. This can lead to staircasing (in c) ) but making steps smaller it converges! https://t.co/dMJehIKDKx
Yes, today it's algorithm day ... maybe tomorrow, too, because I will be on the road for the next 6 h. As always today we will ask the question, what can AI do for us. I say, a lot! But not the ubiquitous neural networks, however here there will be evolutionary optimization! https://t.co/3u1ADzsPMO
Why using optimization for optical antennas, where we can downscale radiofrequency design? Because it is not so easy! Here you will learn about the fundamental differences. The feeding is the worst. There is now AC-generator for optical frequencies! https://t.co/vVwBTm4jdh
So, today I should tell you about outreach, which is so important to connect back to the people. They mostly fund our research via taxes and deserve to be informed and ideally understand. But we just start out baking cookies for christmas, so I might just interfere next week :P. https://t.co/7WOlVZndmA
@StemCorps @MatSciMatt @ThFeichtner [admin] Join us in thanking last week curator Thorsten Feichtner (@ThFeichtner) for an amazing week. https://t.co/29vkwiPMtq
Rachel Oliver
@StemCorps @MatSciMatt @ThFeichtner [admin] "little lights with big ideas" - please welcome this week's curator Rachel Oliver (@ProfRachelGaN ) 🎙️ Podcast and more: https://t.co/JzLF92xERv
RT @realscientists: [Admin] Please welcome our next curator! Julien Cohen (@jul_coh) is an engineer in precision metal additive manufacturi…
Hi Everyone! Let me start by introducing myself! I’m Rachel Oliver (@ProfRachelGaN) Professor of Materials Science at Cambridge University and Director of the Cambridge Centre for Gallium Nitride. I’m going to be talking nitrides and nano this week!
Why nitrides? Well, the nitride materials I work on are used in light emitting diodes or LEDs, the technology at the heart of energy efficient LED light bulbs. Any RealSciNano followers got LED bulbs installed at home? https://t.co/Nz3JDYqlqC
If you have, I bet it’s because of how energy efficient these bulbs are! As much as 6 times more efficient than a traditional incandescent bulb and also better than a compact florescent. Also, they have really long lifespans, up to 50,000 hours. Good, huh?
Inside a typical LED bulb, is a yellow hemisphere of a phosphor material, which converts some of the blue light which comes from the LED into other colours, to make white light. The LEDs themselves are pretty tiny – a few mm across or less. https://t.co/9TNjqBU6eK
That’s not exactly nano though! Later today, I’ll delve into the insides of an LED bulb and show you the much smaller structures from which the light is actually emitted!
OK! Just grabbing a quick coffee, so I’ve got a couple of minutes to take you inside an LED. Here’s an optical microscope picture of a single LED chip: https://t.co/s1ZUeS1PGd
All we can really see here is the metal electrodes which are used to connect the LED to a power source, so let’s dig down under the surface a bit and have a closer look using a scanning electron microscope: https://t.co/QwMUqZiDDO
There's material labelled “n” and “p”. In the family of materials we call “semiconductors” which includes gallium nitride, electrical current can flow via the movement of either negative or positive charge carriers. We call the two sorts of material “n-type” and “p-type”.
When we apply a voltage across the LED, it forces negative and positive charge carriers towards one another. When they meet and combine, light is given out. That’s how we make light in an LED!
(This is very different to how we get light out of an incandescent bulb. There we use a metal wire. Current flowing makes it hot, so it glows to get rid of some heat. We have to create a lot of heat energy & that makes incandescents inefficient. LEDs don’t have to get hot).
If we only use the n-type and the p-type semiconductor, we find that the negative and positive charges don’t often meet one another and combine to give out light. We need to find a way to trap them together in a really small space to make them more likely to meet.
We create a trap for the charges using something called a “quantum well” – and this is where we hit the nanoscale! Quantum wells are layers of one semiconductor material sandwiched between layers of another. The quantum well layers may only be 2 nm thick!
For nitride LEDs, the quantum wells are made of indium gallium nitride – gallium nitride with some of the gallium replaced by indium. We can’t see the quantum wells with an optical microscope, or even an SEM. We need to use a transmission electron microscope: https://t.co/BRgNzS0Mhm
I’ll explain the importance of these InGaN quantum wells a little more! We need to get the positive and negative charges to meet. Imagine that I want to meet a friend in Cambridge… how can I increase the probability of that happening?
If I say to my friend: “Let’s meet in Cambridge” we’re pretty unlikely to find eachother. However, if I say “Let’s meet in front of the Chronophage clock” that get’s the two of us into a much smaller volume and we’re much more likely to find one another. https://t.co/pIKUCtvDA9
It’s the same with the charge carriers: by squeezing them into a tiny space in the few nanometre quantum well, we make it much more likely they will meet, and when we increase that probability, we make the device more efficient. Hooray for nano!
I'll talk more tomorrow about the importance of nanostructures in nitride LEDs. Later today, I'll also post some more resources about these devices, in case you want to dig into the topic a bit more deeply!
Earlier I promised a few more resources on all things LED. My group does a lot of outreach, so here are a few things we've developed over the years...
Our youtube channel has a few videos about our research. This one is a longish watch - but in it I talk a lot about what's inside an LED, and also how we make and study these fascinating little devices: https://t.co/a5x5gokVbt
This infographic explains the impact LEDs can have on society: https://t.co/M5mMLivhiq
If you're thinking about switching to using LED bulbs then you can download our app to estimate how much money you will save long-term because of their superior energy efficiency and lifetime: https://t.co/YXgtXEfqae (The app runs on android devices)
Our second app, LED Lab, is much more in depth, and provides a lot of detail about how LEDs work, with classes at different levels and interactive online experiments. I'd love to hear feedback about it! https://t.co/YXgtXEfqae (This app runs on android).
If you'd like to meet the people behind some of our LED research, we have researcher profiles here, where scientists at different career stages introduce themselves and talk about their interests and careers: https://t.co/hmCCW8cVnu
Morning all! Yesterday I talked about light emitting diodes, LEDs, and I promised I’d delve more deeply into their nanoscale structure today!
LEDs have actually been around for ages (since the 1960s), but in 2014 the Nobel Prize in Physics was awarded for the development of blue nitride LEDs. One of the reasons that making good blue LEDs was so hard is all down to their nanoscale structure. https://t.co/gwn97Fxj8Q
Conventional semiconductors (like Silicon) are grown as single crystals: all the atoms lie in perfect organised rows, like soldiers stood on the parade ground. Those single crystals can be taller than a person, and contains hardly any mistakes in the rows and rows of atoms. https://t.co/0d3XaDkMUA
It’s really, really difficult to grow big crystals like that of gallium nitride (GaN). Big GaN crystals need really high pressures & temperatures to grow, & even now – about 25 years after the development of the first LEDs – we’re a long way from the scale of Silicon crystals!
So instead, we grow GaN as layers on top of another material, most commonly sapphire. And because the spacings between the rows of atoms in sapphire doesn’t match the spacings in GaN, the GaN crystals tend to be full of tiny mistakes in how the atoms line up.
The most important mistake (or defect) in GaN is a dislocation. It’s not really a single mistake, more a line of mistakes that runs right through the crystal. You can learn more about dislocations on DoITPoMs, a great teaching resource hosted by @cu_mat: https://t.co/UJjezczpCq
In GaN there are really a lot of these mistakes. If you looked at 1 cm x 1 cm area of the surface of a GaN crystal, you could find the terminations of about 1 billion dislocations. (For comparison, in Silicon, a 1 cm x 1 cm area hardly ever has even one of these defects).
For LEDs, the key thing you need to know about dislocations, is they can really mess up the performance of the device. For an LED emitting in the infra-red based on GaAs, if you have more than about 1000 dislocations in a 1 cm x 1 cm area it will very rapidly fail.
That’s because when negative and positive charges meet at a dislocation, they combine and give out heat rather than light. The device gets hotter and hotter, and the heat eventually causes it to fail.
Because GaN is full of dislocations, most scientists thought it was a dead loss for light emitting devices. However, it turns out that GaN devices are incredibly robust to the presence of defects.
Understanding the reasons for that robustness was a really challenging puzzle to solve, and caused huge controversy in my field. I’ll come back later and tell you a bit more about that!
Right! I’m back and ready to talk about major nitride controversies! Earlier I said that there are loads of defects in GaN LEDs and the devices survive amazingly well. How could that be? Well there are basically two options:
Option 1: Perhaps dislocations in GaN just aren’t a problem like they are in other materials? https://t.co/hjCPqKasGC
Sadly option 1 doesn’t hold up. We can take pictures of the light emission from GaN and when we do that we can see that dislocations and the areas around them emit a lot less light than material without defects. Dislocations do mess up the light emission in GaN.
Option 2: If the dislocations are a problem, something must stop the charge carriers from reaching them, and hence limit the damage they can do.
Option 2 has legs – there’s lots of experimental evidence suggesting that charge carriers in the InGaN quantum wells (which make up the light emitting bit of a nitride LED) can’t move around freely.
The next big question was this: What is it about the structure of those InGaN quantum wells that prevents the charge carriers moving around?
This is where the big controversy arose. Because there were some really interesting early electron microscopy images which suggested that the indium wasn’t spread out evenly through the InGaN quantum well layer. Instead, the indium atoms seemed to be in little clusters.
Those indium rich clusters would act to trap the charge carriers really effectively, and stop them moving to the defect sites. It sounded like a solution – but it wasn’t. Because later images, taken with other techniques showed no clusters at all.
Tomorrow, I’ll talk a bit about the different techniques that were used. The microscopy is really cool! For now, I’m going to admit that it all got a bit shouty. We scientists can be pretty passionate about our ideas. Not as calm and collected as you might expect! https://t.co/1OMCceyXh8
In the end, most people agreed that the indium atoms were pretty evenly mixed through the InGaN quantum wells. Which meant no more fighting, but we were back where we started… not knowing what it was about the quantum wells that made the LEDs robust to defects!
Here, it all gets a bit complicated. But basically, it turns out that you don’t need a lot of indium in a cluster to trap the carriers and keep them from moving to the defects. You just need a couple of indiums almost next to each other with a nitrogen between them.
And that happens pretty often, even when the indiums and galliums are randomly mixed up through the crystal. It’s like if you’re throwing a dice. Throwing two sixes in a row happens quite a lot if you throw the dice a million times. https://t.co/FiLs1SDmcT
It is in the very nature of the indium gallium nitride alloy that it can trap carriers. The natural disorder in the material is all it takes.
That natural disorder is then vital to making LEDs work despite the prescence of loads of crystal defects. It’s a lucky throw of the dice, on which the multi-billion dollar LED industry relies.
Interestingly, the same natural disorder – and its impact on charge carriers – has also been blamed for the fact that green nitride LEDs are much less efficient than blue ones. But that’s another story!
If you’ve made it to the end of this story, you might want to know that I talk about all this stuff in the extended version of the @RealSci_Nano podcast. Also, I’ll be giving a seminar on this and other LED topics in Bristol on Monday: https://t.co/EP1p8Hlb7N
Tomorrow, I’ll tell you more about the microscopes we used to understand the nanoscale structure of LEDs. In the meantime, do feel free to ask me about LED technology. Other cool nitride folks on twitter who you might want to engage with are…
From Tyndall in Cork, Ireland: @SarojPatrares who has done fantastic work on modelling the impact of nitride nanostructures on how carriers can move and combine in quantum wells.
From Strathclyde in Scotland: @RobMartin100 – who uses scanning electron microscopy techniques to understand the effect of small scale structure of ntirides on light emission.
Also in Strathclyde these days: @FabienMassabuau who is a master of transmission electron microscopy on GaN – although he’s moving towards new wonder material gallium oxide these days!
From Bristol: @CDTR_Bristol - The Center for Device Thermography and Reliability – who may not sound like a nitride group, but actually do excellent work on nitride electronics.
Just looked back at my list of people to check out and realised that they’re all men. I’m sad but not surprised – gallium nitride is a very male dominated field. I’ll recommend fantastic female microscopers tomorrow!
@StemCorps @MatSciMatt @ThFeichtner @ProfRachelGaN [admin] "little lights with big ideas" Extended podcast with @ProfRachelGaN is out now! Chekkit: https://t.co/JzLF92xERv
If you enjoyed hearing about the controversial nature of the nanostructure in nitride quantum wells, have a listen to the extended podcast, where I talk about this story, in a lot more detail! https://t.co/zEWC02VTOl
Good morning followers of all things nano! Today, I’m going to talk about how we characterise the nanoscale structure of nitride materials.
Yesterday – I made a really long thread about a major controversy in the nitride field about the nanoscale structure of InGaN quantum wells. You can read it here if you like: https://t.co/eWrPQF0gjv
That controversy involved data from two amazing nanoscale microscopy techniques: transmission electron microscopy (TEM) and atom probe tomography (APT). I’m going to tell you a bit about each of them!
Let’s start with TEM! TEM got a bit of a raw deal yesterday, because it resulted in some controversial observations which caused some heated debate in the field. Data from microscopes can be hard to interpret, but TEM is really an amazing technique!
Many people will have used an optical microscope to magnify the features of a sample. Optical microscopes are great as long as the thing you want to look at is at the micrometer scale or bigger – so bigger than 1 millionth of a metre (or a thousandth of a mm). https://t.co/0X3Mvbxths
But a standard optical microscope isn’t much use for looking at nanostructures. Light is a wave, and when the structures are smaller than its wavelength it becomes impossible to image them using a basic optical microscope.
So, we need a wave with a shorter wavelength! And electrons (and other fundamental particles) behave as waves. If we accelerate the electrons to high speeds, they have a high energy and a very short wavelength. So we can use them to take really high resolution images. https://t.co/qrMRz8uGA0
In a TEM, we fire the electrons through a very thin sample. This is like transmission light microscopy, where you shine a light through from below a transparent sample, and view it from above. Except in TEM we usually shine the electrons from the top and view from below.
Just like in an optical microscope, we need lenses. But we can’t use beautifully shaped pieces of glass. Instead we might use whopping great electromagnets to shape and direct the electron beam. We call them “electron lenses”. https://t.co/SMCHrPekvF
Now steering electron beams isn’t easy, and the lenses don’t work perfectly. We call the imperfections due to the enses the lenses "aberrations", and the best TEMs have additional components called aberration correctors to deal with the problems they produce.
Once you get the electron optics right, the images can be truly astounding. This one was taken by @fabienmassabuau and you can see it on his twitter profile. It’s a picture of a GaN crystal, and every one of those white dots is a column of atoms viewed end on! https://t.co/B1MzQIiodN
In that image, there is one mistake in the crystal – it’s a dislocation (the sort of defect I discussed yesterday) and you can see how it mucks up the regular repeating pattern of atoms. That mistake goes on, down a line, into the plane of the image.
That raises a very important thing about TEM. We’re firing the electrons through the sample. That means that we are viewing everything in projection. And that can sometimes cause problems. https://t.co/V5JvCh7lrp
There are techniques, like electron tomography, in which you rotate the sample and image it from multiple different angles, which seek to overcome this and get three-dimensional images.
Instead of getting into electron tomography, later on I’m going to talk about a completely different technique for nanoscale imaging in 3D: atom probe tomography. https://t.co/uumjmtoHtb
The next nanoscale characterisation technique I want to talk about is atom probe tomography (APT), which is an amazing way of getting three dimensional compositional maps of materials.
Unlike TEM, APT bears essentially no resemblance to the traditional light microscope. For APT, we have to start with a very sharp needle of material, whose end is only about 100 nm across. These can be tricky to make, but it can be done! https://t.co/BmzvSzu2CG
When a very sharp conductive object is raised to a high voltage, the electric field around the sharp end is huge, big enough to pull ions off the end of the spike. The process of pulling a material apart with an electric field is called “field evaporation.”
In APT, we hold the very sharp specimen at a voltage just below the value needed to achieve field evaporation, and then add a pulse of extra energy to kick it up above that threshold very briefly.
The extra energy can come from a pulse of additonal voltage, or a pulse of laser light focussed on the tip of the sample. For semiconductor materials, we tend to use the laser approach.
If we’re lucky, the pulse of extra energy will evaporate one single ion. It will fly out from the end of the tip along a trajectory defined by the electric field and land on a detector.
The position where the ion lands on the detector can be traced back to tell us where it must have come from on the specimen. That basically gives us its x and y coordinate.
Because you have to evaporate the ions at the end of the needle before you evaporate ions from lower down, the order in which the ions evaporate gives you information about the depth into the sample from which they arise: the z-coordinate.
Now, to get a compositional map, we just need to know what the ion is. We can figure that out from its mass, and we can figure out its mass from how long it took to fly to the detector. Heavier ions go slower.
With a certain amount of mathematical jiggery pokery, we can identify where the ion came from in 3D space and what it’s mass and hence chemical identity are. So, we can build a 3D compositional map.
Like this data on InGaN quantum wells from the first ever atom probe tomography experiment on nitride semiconductors. A classic! Turquoise dots are Ga atoms, orange dots are indium. Green is gold from where we messed up the sample prep! https://t.co/h0fUk89uVT
APT has historically mostly been used to study metals, like in the beautiful image of steel below. But increasingly it’s used for a very wide range of materials. I’ve even met a researcher who is trying to do APT on chocolate! https://t.co/6CXhycghez
I'll be back a bit later to introduce you to some of the fabulous microscopists who work on these types of data!
@Maryam_Eslami Thank you!!
I hope nano-fans enjoyed reading about a couple of the amazing microscopy techniques we use. Yesterday, I promised I’d introduce some of the fantastic people who do microscopy as well… and that I’d tell you about some fabulous #WomenInSTEM at the same time.
Shelly Conroy @ShellySTEM at the University of Cork used to research nitrides using TEM, but has since strayed into range of other materials, including ferroelectrics. She heats these materials up inside the TEM and watches them change!
Caterina Ducati @CateDucati from Cambridge is Director of the Wolfson Electron Microscopy Suite @cu_mat and works on a whole range of nanomaterials. Read more about her on Wikipedia: https://t.co/kW8eAJyrm6
Sarah Haigh @sarahhaigh_mcr at Manchester is a doyenne of studies of 2D materials like graphene in the TEM. https://t.co/7a9KdGTkU0
Sadly not on twitter or wikipedia, but Emmanuelle Marquis at the University of Michigan flies the flag for #WomenInSTEMM in the APT community. Have a look at the data as art section of her webpage; it’s gorgeous: https://t.co/X1srpVVpSg
Having celebrated some #WomeninSTEM, I also want to do a quick shout out to some of my colleagues and collaborators in the microscopy space: @OxfordAtomProbe, @pajb @KuschGunnar @jochenbr @FaircloughSM. All cool people to follow if you’re interested in the nanoworld!
RT @MatSciMatt: This week's @RealSci_Nano curator, @ProfRachelGaN, is sharing some fantastic microscopy and atom probe images along with he…
@h_o_jones @OxfordAtomProbe So nice to hear from you Hannah! I'm really glad you're with the @OxfordAtomProbe group an in my old college! I hope you have as much fun in @OxfordMaterials and @TrinityOxford as I did!
@MatSciMatt I'm afraid, based on my recall of the poster I saw, the answer to "How would that work on chocolate" is "Not very well". However cryo-transfers for APT are definitely a thing: https://t.co/DmPxsfVNwM
RT @ProfRachelGaN: Over on @RealSci_Nano, I've been tweeting about some of the cool folks I know who do fab microscopy, particularly some #…
I’m a bit short of time today – some of my lovely collaborators are visiting to talk about current and future projects. Just time to squeeze in a quick thread before our discussions begin!
Earlier in the week, I talked a lot about nitride light emitting diodes, which can make a huge difference to the amount of energy we spend on lighting our homes and workplaces. So GaN already does a lot for us, but what else can it help with?
Loads of things! Power transistors based on GaN are also really efficient and can be used to make things like laptop charges more smaller efficient. (More about GaN-based chargers here: https://t.co/LE3qS3ZAkm)
Other applications of GaN transistors include being used in amplifiers in mobile phone base stations and in power conversion in electric vehicles. (More about GaN in the automotive industry here: https://t.co/lE0B6x9hT8)
GaN-based laser diodes are at the heart of “BluRay” technology and are also used in displays and even in industrial applications like welding.
Ultra-violet LEDs based on GaN are being developed, and can kill or damage many of the bugs which can infect drinking water, particularly in the developing world, causing sickness and death, so GaN may in future be widely used for water purification. (https://t.co/B3uFtRIoR0)
My group is even developing GaN LEDs which emit precisely one photon (the fundamental quantum light particle) on demand, and these single photon emitters could be used in future secure communications technologies!
So increasingly, GaN is all around us: saving energy, cleaning water, transmitting data, and lighting up our world! And all of these applications require us to understand and engineer the nanoscale structure of this amazing material!
When @RealSci_Nano asked me what my three wishes were to improve the world of science I said "Equality. Diversity. Inclusion." If they'd offered me a fourth wish, I would have said "Accessibility".
I could have spent all week talking about my passion for #equality, #diversity, #inclusion & #accessibility in STEMM! However, I also wanted to talk science! If you'd like to know more about my work & passion in this area, head over to @TIGERinSTEMM or to: https://t.co/0YOqFxjoF6
TIGERS - The Inclusion Group for Equity in Research in STEMM - is a grass roots collective which campaigns for a more inclusive future for science. We've just published a document - led by @DrJessBoland - about accessibility in STEMM, with particular focus on funding processes.
Please do read the document, and if you have a disability, let us know what we've missed by joining the discussion on @tigerinstemm: https://t.co/6AhE2TnFsz
Before I got involved in @tigerinstemm, I hadn't really thought about the barriers disabled people face in scientific research. The more I learn about this, the more shocked I am at how poorly we accommodate talented scientists who happen to have a disability.
TIGERS are focused on funding processes currently, so here are just a few of the things I have learnt about accessibility issues around UK funding processes:
1. Blind and visually impaired researchers use screen readers to access web-pages and documents. However, the main UK funder, @UKRI_News, uses a web-portal for grant submission which is incompatible with screen readers.
2. Similarly, when @UKRI_News publishes grant guidance, they use a pdf format which is also incompatible with screen readers. 3. Sometimes grant info comes on a video instead... but those videos are not subtitled, so deaf researchers can't access them.
4. Some grant processes require interviews. If your disability makes it difficult for you to travel to an interview, you can dial in remotely. But if the technology doesn't work within 5 minutes of the interview start time, your interview will be cancelled.
(How often do any of us get a Skype conference working within 5 minutes? It usually takes me at least 10 minutes of swearing).
5. If you need extra funding for accommodations for a disability, you can request that - but you have to put it in your main proposals documents. Which is a bit like writing "HEY, I HAVE A DISABILITY, DISCRIMINATE AGAINST ME!" across your Justification of Resources document.
I could go on, but if you want to know about this stuff you'd be far better reading the TIGERS report which was written and reviewed by actual disabled people: https://t.co/6AhE2TnFsz
So I'll stop here, but say this: whilst there are a lot of other issues facing disabled scientists, the system problems above are all really fixable. So why aren't we fixing them?? Answers on a postcard to @tigerinstemm please!
Well folks, I hope you've enjoyed hearing a little bit about what I've been learning about the (lack of) accessibility of STEM today!
Another part of my developing understanding of #diversity and #inclusion in STEM is that it's important that all scientists have time for themselves, their families and their other interests...
I'll be focusing on my family over the weekend. My husband's working, so I'm parenting solo, and my Mum's coming to visit Sunday. Hence, I'll be too busy to tweet about all things nano.
Hope you've enjoyed these few days with me in the @RealSci_Nano hotseat! I've been @ProfRachelGaN and I'll be back under my own handle next week tweeting about nitrides, microscopes, diversity, commuting by bike... But for now... https://t.co/ChITWzQOWO
@StemCorps @MatSciMatt @ThFeichtner @ProfRachelGaN [admin] Join us in thanking Rachel (@ProfRachelGaN ) for a wonderful week! https://t.co/45Q7ck0WPx
Matthew Jewell
@StemCorps @MatSciMatt @ThFeichtner @ProfRachelGaN [admin] "Tons of nanomaterials: Big science and little details" Please welcome this week's curator Matthew Jewell (@Prof_Jewell ) Podcast and more: https://t.co/A8f4zCiJxk
@the_jannis @realscientists @ProfRachelGaN There's @realscientists, @realsci_DE and @RealSci_Nano
Very excited to take over the @RealSci_Nano account this week! Here's the plan: Mon - Who is this guy? Tues - Applications of superconductivity in big science Wed - What we do in my lab and why it matters Thurs - Choosing a materials-related career focused on teaching Fri - ???
OK, a little bit about me as we launch a new week on @RealSci_Nano. I'm an associate professor of Materials Science & Engineering at the University of Wisconsin - Eau Claire, located in (and this is going to shock you) Eau Claire, Wisconsin. https://t.co/BwYO1ldmDb
UW-Eau Claire is a primarily undergraduate institution (PUI), and as such our MS&E program is unique. As far as we know, we are the *only* PUI with a full MS&E major degree program in the U.S. Free cookie if you can prove me wrong.
On Thursday of this week I'll talk a little more about the teaching side of what I do, and how a materials research program can fit into a place where teaching is (formally) 80% of what I do.
I did both my undergraduate and graduate work in the @UWMadisonMSE program at @UWMadison. https://t.co/3AjTqFfxqH
@UWMadisonMSE @UWMadison One of the things that got me hooked on science & materials research was the idea that I could contribute something new to society. Early in my undergraduate career I was given the task to metallographically polish and calculate the void density of a wire cable.
@UWMadisonMSE @UWMadison I calculated a value and brought it to my research mentor. "Is this right?" I asked him. He looked at me like I had just landed from another planet. "I don't know," he said, "no one's ever done this before."
@UWMadisonMSE @UWMadison That was it - I was hooked. I was doing something new...was creating knowledge that had never before existed in the history of the planet. So far no one's given me a Nobel Prize for polishing that cable sample, but it started me on my journey in science.
@UWMadisonMSE @UWMadison It just takes a nudge, folks.
@UWMadisonMSE @UWMadison I think what was most significant to me about that was not just that I was learning something new, but that the whole world (in my mind) was going to be trusting my methodology and technique to decide "if it's right."
@UWMadisonMSE @UWMadison I didn't really understand the whole scientific process of peer review and replication at that point, but I did understand that it was important that I sweat the details and get them right. A little responsibility can be tremendously empowering for a student.
@UWMadisonMSE @UWMadison In graduate school I studied the chemical and mechanical properties of superconductors, an extraordinary class of materials that can conduct electricity without resistance. Here's the obligatory YouTube video on how they work: https://t.co/0U4iZS1shf
@UWMadisonMSE @UWMadison That introductory video does a good job explaining the physics of superconductivity, but what it misses is the primarly application: to make big magnets.
@UWMadisonMSE @UWMadison Floating a superconductor above a magnet (the Meissner effect) is a nice party trick, but what really makes them useful is the high electric current densities they can carry when in a wire form.
@UWMadisonMSE @UWMadison Wind a superconducting wire into a solenoid or other shape, push a bunch of electricity through it, and you have a really big magnet. The largest steady-state magnets in the world are all superconducting. Much more on that tomorrow.
@UWMadisonMSE @UWMadison Half-way through graduate school my research group moved to the National High Magnetic Field Lab (@NationalMagLab) in Tallahassee, FL. https://t.co/MPWnrYD82i
@UWMadisonMSE @UWMadison @NationalMagLab Then it was off to the ITER fusion project (@iterorg) in France for a postdoc before landing here at @UWEauClaire.
@UWMadisonMSE @UWMadison @NationalMagLab @iterorg @UWEauClaire Tomorrow I'll talk more about the superconducting magnet systems at all those places (and elsewhere!) and how superconducting materials engineering is advancing the fields of medicine, energy, physics, and more.
@UWMadisonMSE @UWMadison @NationalMagLab @iterorg @UWEauClaire Wednesday I'll talk specifically about the research work we do here at @UWEauClaire in my group, and on Thursday I'll talk about integrating research effectively into an undergraduate setting. Who knows what'll happen on Friday. Come back then and see.
[admin] We are scheduling for 2020! here: https://t.co/HAkcNVreGC https://t.co/BAVLQesYAU
Today we're looking at applications of superconductivity. Specifically, how do nano-engineered superconducting materials enable some of the biggest science projects on the planet?
Application of superconductivity #1: Particle physics It turns out that if you want to know what something is made of, smash it! Physicists have utilized this highly scientific idea for decades to explore the structure of the atoms that make up our Universe.
And the biggest atom-smasher we've built so far is the Large Hadron Collider (LHC) at @CERN. Here's a nice write-up on the LHC and what it does: https://t.co/NCjSqx9dHB
@CERN There's a basic challenge with this design of particle collider...you need to move the particles, in a circle, at something approaching the speed of light. To do this without blowing a hole in the side of your very expensive device, you need to BEND and FOCUS the particle beam.
@CERN Enter superconductivity. Superconducting NbTi wire is used to create dipole magnets that each generate around 7 Tesla (T) of magnetic field. A 1 T magnet is strong enough to lift a small car, so these things put your refrigerator magnets to shame.
@CERN There are over 1300 of these dipole magnets in the LHC ring, and each one weighs 35 tons and is 15 meters long! Here's a short video of CERN engineers manipulating one of the dipole magnets during LHC construction. https://t.co/UlPkUyG67q
@CERN Without superconductors, the LHC ring would have to be much larger in size (and thus much more expensive), and the energy cost to run the magnets would be prohibitive.
@CERN So superconductivity is one important "enabling" technology for particle physics. In the 10 years it has been running, the LHC has realized a number of important discoveries, most significantly the discovery of the Higgs boson. https://t.co/NGRKBVryl5
Application of superconductivity #2: Fusion energy! The old joke is that fusion is 30 years away....and always will be. But in fact there are a number of feasible fusion projects in construction right now, and superconductivity is a big piece of making them possible.
The big big big fusion project is ITER (@iterorg) in southern France. This machine is attempting to generate net-positive fusion energy and (just as important), sustain the fusion reaction for 500 seconds. https://t.co/zQ8LXimzk0
@iterorg I did a postdoc at ITER and worked on their magnet system. Enormous cables of NbTi and Nb3Sn superconducting wires are used to levitate and stir the plasma. https://t.co/VEwEK9vHvm
@iterorg The 500 tons of Nb3Sn needed for ITER were the largest procurement of that material in history...by far! Manufacturing all that complex, composite wire involved eight manufacturers in six countries. We spent a lot of time in airplanes.
@iterorg The key point to understand is that if you tried to generate the ITER magnetic fields with conventional (e.g. copper) magnets, you would need *many* gigawatts of electric power, and you would never achieve break-even fusion.
@iterorg This is a theme for superconductivity: these big science projects (like the LHC or ITER) are already massive in scale. But without superconductors, their size and cost would be absurdly enormous, or (in the case of ITER), they simply could never achieve their design goal.
Hey look at that...those big LHC superconducting magnets we were talking about earlier today? They're getting an updgrade: https://t.co/SuWWeoxJnn
Application of superconductivity #3 - medicine! https://t.co/SN6yMVmMmz
You've maybe spent some time inside a superconducting magnet and didn't even realize it. The largest commercial application of superconductors, by far, is in MRI machines in hospitals.
The big doughnut of the MRI machine is a helium-cooled, NbTi superconducting magnet. https://t.co/pvqsOAN7wq
MRI machines require a highly *stable* magnetic field. With a conventional electromagnet, the magnetic field can vary slightly due to variations ("ripple") in the voltage powering the magnet.
But with a superconductor, you can charge the magnet, and then actually *remove* the electrical leads, and the current will continue flowing in the magnet. https://t.co/08s2mNC5t2
This "persistence" of the superconducting current flow is a crazy physics trick, but it is also technologically critical for MRIs. Producing an accurate MRI image requires knowing the magnetic field value in the magnet bore to something like 1 part per million.
So it's superconductors to the rescue...generating a high, stable, and uniform magnetic field that allows doctors to take that peek inside your body without having to, you know, actually take a peek. https://t.co/luOMkzF5My
Superconductors are also being used to make proton therapy - a more precise and farr less invasive form of radiation therapy for cancer patients - more accessible. https://t.co/baU5CWa6uf
Proton therapy requires manipulating a beam of protons so they can be deposited exactly at the tumor location in a human body. But bending and focusing proton beams takes...wait for it...big magnets.
As a result, there are just a few dozen proton therapy clinics in the U.S. The treatment is massively expensive. Compact superconducting magnets will help make proton therapy more widely available by reducing the size of the machine and lowering the cost.
So there's lots going on in the world of superconductivity...in physics, in fusion, and in medicine. How does this all relate to nanotechnology? Well it turns out we design these superconductors at the nanoscale to get the properties we need to enable all these advances.
Stay tuned for more on how we do that! https://t.co/TCyyo9MPk1
@ClaraMBarker @StemCorps https://t.co/UsZvJWizMe
@ClaraMBarker @StemCorps [admin] "Tons of nanomaterials: Big science and little details" Extended podcast 🎙️ with Matthew Jewell @Prof_Jewell out now! Check it out: https://t.co/A8f4zCiJxk
Superconductors are used to build some of the largest science projects on the planet. But they are also exquisitely engineered at the nanoscale. Today we'll see how!
To help me, I'll be utilizing images from the incomparable Peter Lee at Florida State University. Check out his full gallery of superconductor microstructures here: https://t.co/vpYVFkqZId
Let's start with the workhorse: NbTi. A high-current NbTi wire is comprised of thousands of individual Nb-47 wt.% Ti filaments in a Cu matrix. But there's a lot going on in every single one of those little strands.... https://t.co/xoj0DpRCEX
Magnetic flux in superconductors is quantitzed, and those quanta of flux need to be "pinned", or held in place, to prevent heat generation when current flows in the superconductor. In NbTi, this is done by engineering in ribbons of alpha-Ti in the NbTi matrix. https://t.co/fa8fHJ7NGZ
This is a great triumph of metallurgy...the alpha-Ti precipitates are strain-induced, meaning they develop as the wire is drawn. So the original billet and the desired final wire size have to be engineered to cause just the right amount of Ti precipitation.
Too little Ti and the precipitate spacing won't match nicely the quantitized flux line lattice spacing. Too much Ti and the superconductivity starts to degrade. The LHC was able to be designed and built in the 1990s because NbTi was metallurgically optimized in the 1980s.
Next up is my personal favorite, Nb3Sn. Nb3Sn powers the toroidal field and central solenoid magnet systems of the ITER fusion reactor, under construction in southern France. Like NbTi, Nb3Sn is used by the ton in cables that carry thousands of amps of current... https://t.co/XgewnbsPsr
...and like NbTi, Nb3Sn is able to do it's job because it's been engineered at the nanoscale. In Nb3Sn, there are two competing forces. First, the phase itself has some significant solid solubility. In other words, it doesn't exist only at 25 at.% Sn.
The phase can be tin deficient, down to about 18 at.% Sn. This is a problem, because the superconductivity degrades as the tin content drops off. So metallurgically we want to keep the tin content in the Nb3Sn filaments as high and as uniform as possible.
So, metallurgy students, how do you get and maintain a high, uniform Sn content? Consult a phase diagram and a kinetics textbook, and you'll agree that what we want is a LONG and HOT heat treatment, which for Nb3Sn might be something like 700C.
So what's the problem? Well the problem are the individual Nb3Sn grains. Here they are shown in grey, in a false-colored (red) Cu matrix. Just like in NbTi, we need to pin the quantitized flux somehow. In Nb3Sn that's done mostly via the grain boundaries. https://t.co/uarWPIxhkL
So for maximum flux pinning, we'd like a very fine grain structure, i.e. the formation heat treatment should be as SHORT and as LOW TEMP as possible!
That's the basic challenge with Nb3Sn. We need temperature and time to form the phase via a diffusional heat treatment with high Sn content, but all that diffusion goodness also grows the grain size. What are we to do?
Well we put our engineer hats on, that's what. We've found a few ways to outsmart the material. For example, we can: 1. Keep the filaments small (a few microns in diameter). This reduces the diffusion distances, allowing phase formation to happen without excessive grain growth.
2. We can introduced precipitates (artificial pinning centers, or APCs) that both help to pin the quantitized magnetic flux, and also help supress grain growth.
3. Last, we go for lower temps and longer times in our heat treatments, since diffusion is exponential with temperature but parabolic (square root dependence) with time.
Not every Nb3Sn conductor employs all these strategies (for example the ITER material does not utilize APCs), but together they represent a toolbox that allows us to design a micro- and nano-structure that maximizes the current we can push through the wire.
For example, the ITER Nb3Sn wire can carry about 1,000 A/mm^2 at 12 Tesla and 4.2 K, and Nb3Sn wires designed for high energy physics applications (such as the upcoming luminosity upgrade for the LHC) can carry around 3,000 A/mm^2.
That's some serious current density! https://t.co/cRiKvcegdq
The materials scientists who brought you beautifully optimized NbTi and Nb3Sn figured they had earned at least a nice vacation. But those dang magnet builders are never satisfied...they just want more and more current in smaller and smaller spaces. https://t.co/LXf3JipfNX
So now we are cooking up a whole new generation of "high" temperature superconductors ("high" is a relative term...here we typically mean that it can operate in liquid nitrogen at 77 K or higher) with even more extreme current densities.
And - you guessed it - each of those requires carefully engineered chemistry and structures at the nanoscale to get the most out of the material. It can get...dizzying. https://t.co/5fMbMBwrsM
@ClaraMBarker @StemCorps @Prof_Jewell [admin] Join us in thanking Matthew Jewell (@Prof_Jewell) for an amazing week! https://t.co/8UZZ97sLLo
Tim Drier
@ClaraMBarker @StemCorps @Prof_Jewell [admin] Tiny magnets - what are they for?! - please welcome this week's curator Tim Dreier (@NotHF) from @SandiaLabs podcast and more: https://t.co/0KfGt9If6i
RT @realscientists: [admin] Please welcome this week's curator, animal behavioural ecologist Charlotte Defolie! https://t.co/CGmvOoWamA
Good morning, nano-curious internet people! I'm Tim, regularly on @nothf, Ph.D. chemist and current postdoc at the Center for Integrated Nanotechnologies at Sandia National Lab in Albuquerque, NM. CINT: https://t.co/OloM7c1cmU
Contrary to the beliefs of our present executive, New Mexico is part of the United States and it's also quite lovely. I've been in New Mexico since 2017 because of my previous postdoc at Los Alamos National Lab (also at CINT, more on that later), and at Sandia since 14 Oct.
Soooo....what does all of that mean? Well, it means I completed my Ph.D. a few years ago now, and I've been working on different sorts of nanomaterials research since then. I work at a Dept. of Energy laboratory, there are many of them: https://t.co/sncYRihTme
Within the Dept. of Energy (DoE) complex of labs, there are a number of Nanoscale Science Research Centers (NSRCs). I work at one of those. https://t.co/gdilzToQ5W
The NSCRs are user facilities - meaning any scientist can submit a proposal and if it's accepted come use our facilities. We have users from all over the world, from within US academia, and from other parts of the DoE.
For users from academia or government research facilities, whose work is going into the regular scientific literature, there is absolutely no fee to use the NSRCs. That's right, COME USE OUR STUFF FOR FREE.
At CINT our capabilities are in clean room stuff, and electron microscopy, with a number of laser spectroscopists up at the LANL facility. CINT is unique among NSCRs in existing at both Sandia and Los Alamos national labs. It's above my pay grade to know why that happened.
Throughout the week I'll be talking about my work, some of my previous work, how I ended up here, Tweeting may be in the evenings US time because access to the outside world via the internet from work is a bit spotty.
Okay, I had my parents in town this weekend, so I didn't get a lot of tweeting done today. Hoping to actually have a minute to do some tweeting tomorrow. Please check out the intro posts on https://t.co/wzthhO8CBz
Tomorrow I'll be back to talk about my background, where I work, how I got the job I have, and what the big picture stuff for my research is - the context that makes what I work on more than a curiosity to a vanishingly small number of people.
The main thrusts will be why things that are on the nanoscale have behaviors different than either molecular or bulk materials, why that matters, and what I actually *do*. Hopefully I can show some pretty pictures from stuff that's been published.
Previews: Gold, more gold, iron, CHEMISTRY. For tonight a final pitch - if you are a researcher (PI, student, postdoc, tech or otherwise) in nanoscience, please consider taking advantage of the NSRCs. In particular, come to CINT! https://t.co/LDCs5LD0Gv
One thing I definitely need to mention and will try to remember to mention every day - I am tweeting here in my personal capacity, I do not represent CINT or Sandia National Labs and any opinions expressed are my own. I make nanoparticles, not opinions, for Sandia National Lab.
HELLLOOOOOOOOO! Turns out that I can get access to Twitter from the SNL computer network, so while I'm drinking coffee and waiting for a molten metal bath to warm up (more on that later) I thought I'd start sharing a bit about who I am, what I do, and all of that kind of stuff.
As always - today I am tweeting in my personal capacity, my opinions are my own and do not reflect any position of Sandia National Labs, the Department of Energy, or NTESS. I figure work can't get too upset with me if I put the disclaimer up daily.
I talked a little about the Center for Integrated Nanotechnologies, where I work, yesterday. This morning I want to talk about my background and how I got here.
So brief biosketch: BSc. Economics 2004, U Oregon BSc. Chemistry, 2011, U Texas San Antonio Ph.D. Chemistry, 2017, Colorado State University Research interests: how nanoparticle forming reactions work, controlling nanoparticle formation, nanocomposites (ex. polymers + NPs).
Current Position: Postdoc, Center for Integrated Nanotechnologies (CINT), Sandia National Lab. Previous: Postdoc, CINT, Los Alamos National Lab
So I've had a bit of a circuitous route to here - having spent some time as a working bank analyst before getting into science - but generally speaking I'm excited about where I'm at and the potential to accomplish interesting stuff. Also working in a cubicle was not for me.
One more quick shout-out for folks interested in chemistry generally - check out the #ChemTwitter and #RealTimeChem hashtags because there are great people there and there's always some fun stuff getting talked about. Chemistry twitter is pretty good, on the whole.
So that's a little about me briefly. In more detail I did my doctoral work on understanding how thiolated gold clusters are formed. I was able to figure out why the reaction requires oxygen to work in both organic solvents and water, and isolate an important intermediate.
During my first postdoc at LANL, I worked on self-assembling nanocomposites. Unfortunately a lot of that work didn't go like one would hope - these things happen - but I was able to show that you can change AuNP properties in composites by changing Au ion coordination. Sort of.
I started here at Sandia back in the middle of October, so I haven't been here all that long. I'm looking at a 2-3 year appointment to work on a few related projects having to do with magnetic nanoparticles.
And why would one care about magnetic nanoparticles? My boss and a few others had a recent perspective on this! https://t.co/wU0mGO8TOh
All right, got busy with actual work during most of the day today, but I guess let's start talking about magnetism. But first, an important announcement in a RT to follow for my USian tweeps.
RT @DrLothar: This thread! @cmclymer is rallying the troops to fight an impending regulation change to allow discrimination against our LGB…
So if we're going to talk about magnets, we need to know about magnetism. I can't really do better by way of simple explanation that National Geographic, so I'm not going to try: https://t.co/kJWmWoqj1O
In sum - electrons have a property called "spin," and you can think of this like spinning a basketball on your finger (SHOOSH PHYSICISTS I KNOW!). If you have one ball spinning clockwise and the other spinning counterclockwise at the same speed, the sum of the spins is 0.
The same is true with electrons - if electrons are paired up they have opposite spins (+/- or ↑/↓ or ɑ/β) and the net spin of the system is 0. If electrons are unpaired, the net spin of the system is not zero. Non-zero spin = magnetism.
That's the gist, anyway. Things can be more complicated than that, but for our purposes at the molecular level that's what we care about. Okay, great. Well... there's more than one kind of magnetism and that's where things start to get funky.
I'm going to link you to the Wikipedia page on magnetism, but only because the references are okay. It's really jargony and I'm new to working a lot on magnetic systems myself. https://t.co/6lwLryKq9E
Broke the thread because I am a foolish fool. https://t.co/eQQRwmIGYk
So, there are several kinds of magnetism and we should talk about a few of them so we can start talking more about the magnetic properties of nanoparticles tomorrow.
Diamagnetism - we usually think of it as all the spins being paired up so the system doesn't magnetize in response to a magnet. Think of a block of wood, or a gold watch band.
Paramagnetism - there are unpaired electrons. What's that mean? Non-zero spin and therefore magnetism. They'll magnetize when exposed to a magnet, but when the magnet goes away don't remain magnetic.
Ferromagnetism - This basically means "magnetic like iron." There are unpaired spins in ferromagnetic systems just like in paramagnets, but ferromagnetic materials can be made into permanent magnets below a certain temperature.
In ferromagnets spins near each other align parallel* to each other. ↑↑↑↑↑↑↑↑↑↑↑↑↑ Because the spins all point in the same direction, they add together. *technically the moments of neighboring magnetic domains, but that starts to get REAL complicated.
There's also ANTIferromagnetism. Those are systems where there are unpaired electrons but the overall spin is zero because the spins of individual unpaired electrons align anti-parallel: ↑↑↓↓↑↑↓↓↑↑
Lastly there's ferrimagnetism. This one is the weirdest because it has properties of both ferromagnetic and antiferromagnetic systems depending on temperature.
Ferrimagnets, like ferromagnets, will remain magnetic after they've been exposed to a magnetic field if they are cold enough. HOWEVER like antiferromagnets, their spins tend to align anti-parallel if left to their own devices.
This can happen because of the structure of ferrimagnetic materials - in a sense there are more spins aligned one direction than in the opposite.
Ferrimagnetism and another property called SUPERPARAMAGNETISM will be important when I talk about the nanoparticles I'm working on tomorrow.
Good morning everyone! Light I left off with a brief intro to magnetic materials written from the perspective of a chemist who is pretty new to working on magnets. https://t.co/eImttztZuA
Today I want to get into why anybody would care about nanoscale magnets and what some of the goals of my present research are. As always, any opinions expressed are mine alone and do not reflect any position of the DoE, Sandia Lab, or NTESS.
I mentioned superparamagnetism yesterday, and I want to take a second to explain what that means. So there's a super jargony Wiki page, like one might expect - https://t.co/KNveIZ4X5Q
In terms that make sense to me, a person without a degree in physics and who hasn't done math more complicated than calculus in years, it's like all the spins in nanoparticles are acting like one GIANT spin.
If you have a nanoparticle made of a ferromagnetic or ferrimagnetic material - like magnetite, say - the spins will all couple up so the particle will have what we call a single magnetic domain.
More or less that means that when you put them into a magnetic field they behave a lot like paramagnets but they respond more. Their susceptibility to external magnetic influence is higher.
Unsurprisingly, we call how much a sample responds to an external magnetic field its "magnetic susceptibility." Higher susceptibility can be important for a lot of things - data storage, medical imaging, electronics.
Susceptibility is also related to another property that can be important for how your magnets perform called hysteresis. Again, I'll give you a link to the wiki for the references: https://t.co/niE0tCRZid
So we've talked about how magnetic materials will respond to other magnets, well, if you put them in a strong enough magnetic field the magnetic moment of your sample will align with the direction of the external field.
It's not unlike how a magnetic compass works, but you're using a field you generated rather than the earth's magnetic field. And if you have ever used a compass, you've probably noticed that there is a delay between when you turn and the needle moving to a new position.
If you take magnetic particles, put them in a big magnetic field, and then change the orientation of that magnetic field while observing your sample's magnetic orientation you'll see a delay as well. Your sample won't instantly realign with the field, it'll take some time.
We measure how magnetized the sample remains as we change the field strength and orientation, and that tells us about the magnetic behavior of our particles. Sometimes you want a lot of hysteresis - like with a hard drive - in our case, we want none.
Why would particles that respond nearly instantly to the orientation of a magnetic field be useful? That's going to have to wait until I've gotten some science going in the lab.
All right, I have my experiment going and it's going to have to run for most of the rest of the day, so let's talk about why having particles with no hysteresis can be useful. https://t.co/HLA2yW4rEq
Transformers are a part of the electrical grid, I'm sure everyone knows this. Some hang on power poles in your neighborhood, some are huge and centralized somewhere in the grid.
Transformers change the voltage between the input and the output - for instance taking the high voltage transmission power from the lines outside down to something usable in your house. In the US residential voltage is 120/240 V.
What does that have to do with magnetic nanoparticles? Well, a key part of a transformer is an inductor, which is basically a magnet with some wire wrapped around it. These are often called cores. Inductors store energy when current is passed through them.
Inductors also appear on circuit boards, in radios, etc, for a variety of different applications. I'm not an electrical engineer, so my knowledge of this stuff is a bit sparse, but the point is that inductors are important and that inductors are made of magnets.
Well, because electric current and magnetism are really the same thing - the electromagnetic force (one of only four fundamental forces in the universe no matter what some cranks in Austria say), the magnetic field of an inductor responds to the field generated by current.
As the current changes so does the field it generates, and the inductor's magnetic moment will follow it - like the compass responding to the Earth's magnetic field.
And as we may remember from earlier, there's a bit of a delay in the response. Over time, this adds up and the inductor's magnet gets less and less synchronized with the current's field. That leads to a loss of stored energy. https://t.co/uBGFMmJ8KE
As time passes you get a build up of magnetization in the inductor, leading to hysteresis like we talked about early. The higher the hysteresis the greater the loss of energy in your inductor, leading to worse efficiency.
To bring this back around to nanoparticles - superparamagnetic nanoparticles have almost no hysteresis (ideally none) at ambient temperatures. So if we could make inductors out of superparamagnetic particles we could massively improve efficiency across all kinds of applications.
The big one is large transformers in the power grid, which are something like 80% efficient if I remember correctly. The transformers in your neighborhood are about 96% efficient, but because there are so many small gains represent major energy savings.
@ClaraMBarker @StemCorps @Prof_Jewell @NotHF @SandiaLabs [admin] Tiny Magnets - what are they for?! - in conversation with @NotHF Extended podcast out now: https://t.co/0KfGt9If6i
Good morning fellow people for whom it is morning. Usual disclaimer that any opinions expressed are my own and not those of SNL, the DoE or NTESS. So, we covered spin and kinds of magnetism earlier in the week. Thread: https://t.co/fVpb03ZpFR
Today I while I have some time during the day I want to talk a bit about what I actually do. By training, I am a synthetic chemist. That means that I take molecules we don't like, and use chemistry to turn them into molecules or materials we want.
My synthetic experience is pretty broad - I've done everything from small molecule chemistry to inorganic nanoparticle synthesis. I joke that I'm one of the only people I know who's comfortable working in a glove box or running PAGE.* *polyacrylamide gel electrophoresis
But, the reason I've spent so much time earlier in the week talking about magnets is that at the moment I'm working on magnetic iron oxide particles.
We're interested in magnetic nanoparticles because magnets are super important to the modern world, like I mentioned yesterday. https://t.co/BPvwiuUYZH
One problem in magnetic nanoparticle synthesis is reproducibility. Another is size control - both in terms of getting the desired size and in having a narrow size distribution.
These two problems exist across a lot of nanoscience, but can be particularly troublesome for iron-based particles. Why? Well, FeNP synthesis is usually done at really high temperatures, like 350 °C high. At that kind of temp, all kinds of things happen, it's a mess.
You also run into issues of thermal transport - it is really hard to keep your reaction vessel a consistent temperature when it's that high.
So how do we overcome the temperature challenge? By using a molten metal bath! Our awesome tech (BIG UPS TO TECHNOLOGISTS & TECHNICIANS!) converts soldier pots for use with some custom software he wrote & high performance thermocouples.
As a result, the group developed a pretty cool and very reliable synthesis of magnetite nanoparticles a few years back. https://t.co/DE3KPBjW18
Not everyone will have access to that paper (I am happy to send a pdf if you don't, just let me know), but there are some pretty cool images I think are worth seeing. All the scale bars are 20 nm. https://t.co/iee7Qu6wfv
These images are from a transmission electron microscope (TEM), that we use to see stuff too small for optical microscopy. As you can see the drip-feed synthesis the group developed makes very regular particles with size predictable by reaction time.
And also in that third image look at how nice and hexagonally close packed those spheres are! Symmetry is fun.
If you want to know more about electronmicroscopy, I can't say enough good things about Grant Jensen's lectures. He's a professor at Cat Tech, and what he's put up on YouTube is a really great way to get started (it's how I learned the basics). https://t.co/VxWTTbQIfo
So, the group developed this extended FeNP synthesis a few years back, so what am I working on? Well, it's an update to that procedure that is easier to do. I'm also working on making particles that don't just contain iron, materials called ferrites.
Because of my interests and experience I'm trying to control particle size in our new synthesis, figure out the best way to incorporate other transition metals, and the best ways to stick different stuff to the surfaces to make the particles better for inductor applications.
I can't show you any of the results from those experiments for a few reasons - mostly they're not published or in a publishable state yet. But, because I work at Sandia, any photo I release has to go through an approval process that can take some time.
ETEM is "environmental TEM" it allows us to do things like flow gas into the microscope and look at reactions in progress. 4D STEM is a technique that collects just A TON of data and lets you understand really fine details about your samples. https://t.co/L7z0wXBcBX
Hello all, good morning, I haven't had as much time to tweet this week as I had hoped, but that's good for my life here at the science factory! As always opinions of mine do not represent SNL, DoE or NTESS.
Yesterday one of the microscopists here got some really nice images showing that I'd made particles without any surface oxidation. They're an intermediate of our synthesis of magnetite, which is why we're interested in them. Understanding how these convert to magnetite is good.
So the result from yesterday means today we're doing Environmental TEM on the samples. We'll be exposing these nanoparticles to gas while they're in the TEM and observing what happens. Some serious #RealTimeChem to help us understand more about our particle synthesis.
I'm pretty excited because it took a few tries to get the particle quality we needed. I synthesized them in a molten metal bath under nitrogen, capped them, pumped them down on my hi-vacuum line, and immediately put them in our inert glove box.
I had to build a custom nitrogen tent around the metal bath, and figure out how to get the mechanical stirrer setup so not to interfere with it and also not melt the plastic on the 350 °C metal. I wish I could post the pictures, but I'd get in a serious amount of hot water.
The nitrogen tent was needed because you do part of the reaction with your flask open under nitrogen flow to cook off some of the stuff from the precursors, so I needed a way to have an inert atmosphere around the reaction vessel while I did that.
After the reaction was done and I had them in the glovebox, I had to figure out how to purify them. Normally we use a centrifuge, so I had to track down a very tiny centrifuge that I pumped into the box.
Once I had the tiny centrifuge and some tiny centrifuge tubes in the box, it was a matter of repeatedly precipitating, centrifuging, and resuspending the particles. Over the course of 10 washes I got essentially all of the stuff we didn't want off of them.
Next our microscopist pumped a special kind of holder into the glovebox, it keeps samples inert and he used that to load our sample into the ETEM. Once it was in the instrument, it could just sit there because it's under a pretty hard vacuum.
Today we're flowing gas to look at some surface reactions. We'll probably get some video, but it's 2 GB per second so we won't get long videos. We'll definitely get some high quality images every few minutes.
The computer setup running this microscope (the instrument is from FEI) has a half a terabyte of RAM and a 40 TB storage setup. It can't be connected to a network for security reasons, so with huge file sizes it needs a lot of local storage.
And now I'm off for lab cleanup day! Sandia does an official shutdown from 25 Dec to 2 Jan, so my last day of work for the year is Tuesday next week. As such, we're cleaning the labs today and tomorrow so everything is in a nice state when we get back, and safe for the break.
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Speaking of magnets, this is pretty darn cool. https://t.co/nT6MYzULL9
Hello! Sorry about neglecting yesterday, got hung up doing actual work at work. Today I am trying to recover from this cold, so I've mostly been laying around. Anybody want to talk nanoscience before I hand over the keys in a few hours?
So, I mentioned a cool experiment we did on Friday. Well, really that one of our microscopists did on material I synthesized. Turns out we got the data we were hoping to get! Saw some really cool changes on the particle surface.
Our next steps will be to use other techniques to try and get a handle on the reaction kinetics, so that'll be fun! We also have quality magnetometry data on the sample.
Well, I'm about to turn into a pumpkin, as I officially hand the keys back over in about 90 minutes, and I am oh so very tired. It's been fun! Thanks for having me @MySci_PK! If you're interested in hearing more about science occasional or more about RPGs often follow me @NotHF
@ClaraMBarker @StemCorps @Prof_Jewell @NotHF @SandiaLabs [admin] Join us in thanking Tim for a wonderul week @NotHF Podcast and more: https://t.co/0KfGt9If6i https://t.co/QYHZElwnF3
2020
Andrew Princep
[admin] "Queer and Quantum Magnetism" Please welcome the 1st curator of 2020, Andrew Princep (@AJPrincep ) podcast 🎙️and more: https://t.co/fh00JdUPX9
Hi Everyone! It's nice to meet you all. Please be sure to check out my podcast interview with @MySci_PK in the pinned tweet. You can see another short interview about me in this YouTube video made by @Kathryn_EB for @QM_Oxford : https://t.co/uNtHQsgQRU https://t.co/YuMqmO6HKm
I'm a research fellow at @wadhamoxford and @isisneutronmuon and my research is basically focussed on looking at atoms, and then way atoms interact with each other, to understand why we have things like metals, insulators, magnets, and superconductors. https://t.co/OzQnR59gJK
I look at atoms using beams of particles produced by places like @isisneutronmuon @DiamondLightSou as well as overseas at @esrfsynchrotron and @ILLGrenoble. These are giant international facilities helping scientists look at matter on scales from proteins and viruses to atoms https://t.co/K1YEKdxLTO
Over the week I will talk about my research, explaining some things about what matter is like at the atomic level, how magnetism works in materials, how i can look at that with particle accelerators, and why we spend so much time and effort to do so! https://t.co/iB3gOM8LIb
I will also be attending two conferences: Frontiers in Condensed Matter @BristolUni, a physics conference that will showcase cutting edge developments in my field. And the @LGBTSTEM LGBT STEMinar @unibirmingham, a conference for LGBT scientists to network and share their research
Please feel free to ask me questions! I'm happy to talk about any aspects of materials science or condensed matter that I can. For the first 2 days of this week though I am officially on a holiday in Canada, so to avoid my boyfriends wrath content will be intermittent.
@MysterMyke @ProfRachelGaN This image depicts the arrangements of atoms in a crystal of some material. The colour of the spheres are different elements, the tetrahedrons and squares are guides to the eye so you can see the geometric patterns exhibited by some of the atoms.
@MysterMyke @ProfRachelGaN I'm not 100% but I'm fairly sure this is a copper based high temperature superconducting material
Looks like we will both be there and madly tweeting about the work done by LGBT scientists! https://t.co/4YUI9Z9e1o
@MysterMyke @ProfRachelGaN Any time!
Probably the first thing I will talk about is my journey to get where I am today. Our story begins a long time ago, in a country far, far away: https://t.co/MT80C06rsn
I went to a highschool in the city of Perth, in Western Australia. It was a school in a fairly mixed suburban neighbourhood with relatively poor academic attainment. In my graduating class of ~100, about 10-15 of us went to university. https://t.co/z3GaA8PFsg
At highschool I did quite a variety of subjects: Economics, English Literature, Applicable Maths, Calculus, Physics and Chemistry. This is common in the Australian system, although very rare in the UK. I applied for and was accepted into the Nanotechnology degree at @CurtinUni https://t.co/fDWDXYBznl
@CurtinUni I chose nanotechnology because I wanted to "do something space age that would lead to a career in research". I was very lucky that the degree was run by @MarkIOgden who was an excellent lecturer and mentor, and we are still friends and collaborators over a decade later!
@CurtinUni @MarkIOgden Unfortunately for Mark, during the 3rd year of the 4 year degree, I met the incredible Dr Annemieke Mulders, who taught my electromagnetism course. I was incredibly taken with her, and she was kind enough to offer me a holiday research project and then an Honours project. https://t.co/jXKotLvCqH
@CurtinUni @MarkIOgden My research under Anna was on neutron scattering, magnetism, and unusual behaviour of rare earth atoms in metals. Not the kind of stuff that any of my peers worked on, and it was indisputably Physics! Thankfully they allowed me to do the project anyway, and I had an amazing time.
I managed to graduate (just, hah) with a first class honours which was enough to get me a government funded PhD place, working with Anna on the same "weird crazy exotic" stuff from my holiday research project. Some of the stuff Anna said at the time really stuck with me:
She had offered me a PhD working on multiferroics, a hot topic at the time, but I specifically requested to continue the electronic multipole project from a year earlier. She said "This is not sexy science. Few people will read your papers. But if you are passionate, then fine."
This has informed how I talk to students who come and ask me for PhD references. It's really important to think about where the research in your project fits into the global scientific paradigm. 'Sexy' science is more likely to lead to papers which get you an academic job.
At the same time, if you find that project boring, it wont sustain your interest for 4 LONG gruelling years. So you need to balance that tension along with how you feel about the group you work with and your supervisor.
In the end though, I did my work on multipoles and thankfully I used techniques - Resonant X-ray Scattering and Neutron diffraction, which have been extremely helpful throughout my career https://t.co/xIl57yE03S
There was a major hiccup 18 months in though - Anna got the offer of a Lecturership at @UNSWCanberra. She made sure that I could come with her, and made the offer - It was really hard to say yes and leave my life behind but I said it almost immediately.
This is how I ended up finishing my PhD at perhaps the strangest university in Australia! I grew up a lot very quickly, but I feel it would have been impossible without financial support from my family if I'm honest. https://t.co/2ExKwxJPOu
I really enjoyed my PhD, I went to France, Japan, Germany and Switzerland to do experiments and attend conferences. I finished my thesis more or less on time (I may have had a bit of a fight with Anna over when to submit and why, but I got my revenge by spelling her name wrong😅) https://t.co/sH14W1g8Iy
After my PhD I had a crisis of faith - did I owe it to my 8 years of education to get a well-paying job? Or should I rather continue in academia? I applied for academic jobs anyway while I pondered this, and I was interviewed by Prof Andrew Boothroyd @OxfordPhysics @UniofOxford
@OxfordPhysics @UniofOxford I applied for 3 jobs actually, all in top labs. I only ever even heard back from Oxford! Anyway, weeks went past with no word from anyone, but then out of nowhere I got an offer to start a 3 year postdoc at @QM_Oxford https://t.co/guR9zOFwIK
@OxfordPhysics @UniofOxford @QM_Oxford I was extremely lucky with this, because again my family helped me out financially with the move. IDK if youve ever flown from europe to australia but its not cheap, and living in Oxford is *eyewateringly* expensive. My job also paid a large amount to help me relocate.
Not all postdocs are so lucky - but this is NOT how it should be. A career where you are *expected* to move across the world has to also be one which makes that possible financially rather than grinding everyone into poverty or excluding people without families to help.
Anyway my luck continued unabated for quite a few more years - my 3 year postdoc was extended to 4 years because another postdoc left early and there was also some money left over on the grant that had employed me. @QM_Oxford also won an EPSRC platform grant to support postdocs
and as a result, I was gifted with another extra year of funding. During this time I also applied for a postdoc @hzbde which was unsuccessful but they asked me to visit for 6 months to start some new collaborative projects, which Oxford was happy to accommodate. https://t.co/aRHkkCI3jO
A sad note here is that shortly after I finished my PhD Anna felt compelled to leave science due to the worsening situation with australian research funding and changes at her institution. Jokes on the ARC though because now she is a successful artist! https://t.co/WBnW9ZYfdc https://t.co/sK4wEbrJn2
@HZBde After all that though, it was time to sing for my supper again. I spent months preparing to early career research grant applications, put my heart and soul into them, and in both cases was rejected. I even got told "great project, very timely, needs to be done by someone better"
@HZBde That was an extremely bitter pill to swallow - clearly I needed to do another postdoc but there were very few suitable ones. I interviewed for the only one I thought was suitable, and they told me I was their backup candidate. I was now jobless, and that would last 3 months. https://t.co/PYTRVpUPeD
@HZBde Living off my boyfriend and my credit card financially, I got quite desperate at this point, I applied for jobs at hedge funds, one of them flew me out to Malta! Im glad they didnt offer me this job, I would have been lonely and I hate seafood. https://t.co/rUoq700IBy
@HZBde A few days after I was told I was "insufficiently quantitative" for the hedge fund job, I got the news that the first choice candidate for the science job had fallen through and I was to start as the Keeley-Rutherford Junior Research Fellow @wadhamoxford @isisneutronmuon
I think its important to tell this story in detail so people realise that academia is a rough career sometimes - you can easily end up unemployed living off credit due to fixed term contracts and shortage of jobs.
Thats how I got to where I am now! Ive had an *amazing* time in my current position. Teaching incredible students, working with great people and doing super fun research. But I only have 9 months left on this contract, and deciding what to do next is going to be very tough.
Its highly unlikely anyone will have read all bazillion tweets to get to the end here, and I promise to be more concise with future threads! But this is a long complex story and its one many young students or non-academics do not realise might exist. https://t.co/8wu6g44RSu
@ProfRachelGaN Only the undergrads and military postgrads had to do that thankfully
@realscientists In Australia if you had a first author publication you could use this *in lieu of a first class masters* when applying for a PhD. I think this basically sets the tone for how reasonable it is to expect someone to have a paper before starting a PhD
@derrick_a_rob Thank you very much!
Okay, while Im on a train, lets talk about crystals! https://t.co/9PlNSfTu9p
Crystals are a pretty fascinating topic for a lot of people, but for a lot of different reasons. People recognise some things as being crystals (i.e. the image above) but not a lot of other common materials - iron / steel, rocks, many sands, etc.
Even a lot of plants have some degree of crystallinity in their cellulose fibres! But of course, this gets to what it means to be a crystal as far as scientists think: being a crystal is about being ordered and regular at the atomic and molecular scale.
Lets take a pretty common example: table salt! A lot of people might remember that table salt has the chemical name sodium chloride, which means it is made up of equal parts from the elements sodium and chlorine. https://t.co/KgSNgPZrfI
Salt has another name: Halite! Theres not a huge difference between what we call salt or halite (im sure the geologists will have something to teach me on this, but im talking broad brushstrokes). https://t.co/1Nn4N7B57I
In both cases, when you zoom in to the atomic scale, they look like this (but obviously without colour!) https://t.co/BpWGel2qhK
The regular structure of crystals is extremely helpful for physicists like me, because it means we can mostly get away with understanding what happens in one little bit of the crystal - by the principle of symmetry it is enforced to be the same everywhere except the surface https://t.co/BlPAysaMu1
not all materials are so simple, however. Most high temperature superconductors have a very complicated crystal structure! https://t.co/BMbIqDs1zD
@tonyver45 There really is! The mathematics of group theory was developed mostly in the early 20th century. It has very deep applications in quantum physics but also in the study of crystal structure.
@tonyver45 You can use group theory to show, for instance, that there are only 230 possible three dimensional crystal structures! And by relating the symmetry of properties like magnetism and the symmetry of crystals, you can tell if a given crystal can display a particular property
@tonyver45 This has been especially useful in studying multiferroic materials, which display magnetism AND a property called ferro electricity. There are only a handful of crystal structures which can support both
@bat__go Hahaha well I am talking about relatively crude understanding- is the material a metal or an insulator, magnetic, ferroelectric, will the properties be strongly anisotropic, etc. Nothing quantitative
@bat__go I will yield to you freely on this one!
In some cases we learn a lot about a material from the structure alone, in other cases it is merely a starting point. Graphite, the material that we use in pencils, consists of layers that dont connect to each other very strongly and this is why we can write with it like we do https://t.co/V0xwNcwkol
but this is also why it can conduct only electricity within the honeycomb-shaped sheets of carbon atoms - not between them, so it is a good conductor in two directions but an insulator in the other one! https://t.co/3qChwbm4l5
one of my favourite relationships between structure and properties is the famous example of chocolate! A *lot* of time and energy was spent determining that chocolate has six, slightly different, crystal structures (for the cocoa -chocolate is a complex mix with fat and sugar) https://t.co/b2LlTbr7KD
This is super important because of the 6 types of chocolate, only one melts at the right temperature for the human mouth while also being smooth textured and providing you with the "snap" you expect from a good chocolate bar https://t.co/lJwB2NcFMF
Because of this, a lot of effort was put into working out how to ensure that you can reproducibly make the right kind of chocolate from your industrial cooking method. This also explains the phenomenon of "bloom" in chocolate that is left out too long (who ever would??) https://t.co/8Tflsacfy1
bloom is caused when some of the Type V chocolate (the good one) converts into Type IV, III, II or I which are all more thermodynamically stable. This is like what people tell you about diamonds turning into graphite over time, except it will actually happen😅
Thats all I have to say about crystals for now, but feel free to ask me anything you like if you have some questions! It can be as complicated as you like, and I am a master of group theory (Im not really, but I dabble)
@schrodingerskit To the best of my knowledge its actually a myth. Graphite is thermodynamically more stable but the conversion has an activation energy that makes it impossible practically.
@schrodingerskit My understanding is that basically everything we know is derived from experiment, up to and including basic properties like melting point (but certainly things like snap and mouthfeel). As for the structures of the other 5 types, I can try and find out but im afraid i dont know
@Orad I appreciate the love!
@schrodingerskit Apparently a back of the envelope calculation suggests 10^80 seconds, so there definitely wont be atoms by the time it could happen :P
@schrodingerskit This is the only thermodynamics joke that I will ever need: https://t.co/XtYlNj6Ulb
@JoeWillsher Claire would have found it a lot easier with the aid of a synchrotron.
RT @realscientists: Check out this cool mini-thread on making scicomm boardgames! They sound amazing 😍
RT @professor_dave: If work was the only thing giving substance to my life, I suspect the thin gruel would have killed me by now. You only…
@AJPrincep [admin] "Queer and Quantum Magnetism" the extended conversation with the amazing @AJPrincep is out now: https://t.co/fh00JdUPX9
Okay, theres been a bit of a break because I had to change countries and the lack of sleep has left me a bit frazzled, but I am here to do my best to explain the phenomenon of magnetism! https://t.co/Fomslgeq6l
To start, I will take the humble bar magnet. And then I will do terrible things to it https://t.co/ifP0fowlAZ
What would happen if we cut our bar magnet in half? The universe does not permit the separate existence of a north and a south magnetic pole, so you must end up with two separate bar magnets! https://t.co/2zfL4ktJ57
BUT WHAT IF WE KEEP CUTTING!?! https://t.co/hHPN5N3bg6
It turns out that the very atoms in a bar magnet behave themselves like bar magnets! If you really wanted you could keep going beyond the level of atoms, down to electrons and subatomic particles, but this is detail that isnt necessary for us. https://t.co/SZoEl3ybRd
This is due to a quantum mechanical feature of particles could Spin: electrons have it, and because electrons can be either paired (with an electron that has opposite spin) or unpaired, atoms with unpaired electrons will tend to have a spin and can thus show magnetism. https://t.co/vaTWfFG8Rf
atoms having a magnetic moment like this is fairly common, so we might wonder why more materials arent magnetic. But when we look at two atoms next to each other, theres a lot of different ways they could be aligned right? Why one and not others? https://t.co/A5bV1Vsb1K
The detailed answer requires a pretty astonishing amount of quantum mechanical calculation, but it actually turns out you can often reduce this problem to an interaction that says: the atomic magnets want to be either parallel, or antiparallel, and antiparallel usually wins!
But this is based on a fairly simple idea where each atom only cares what the atoms right next to it are doing. What if you care about what atoms further away are doing? Well, then it gets very complex! But my favourite result is the spin spiral: https://t.co/cyqMnJl3le
Spin spirals can happen for lots of reasons, but the simplest one is that you want to be antiparallel to your neighbour, and to your neighbours-neighbour (the next-nearest neighbour). Spin spirals happen in a lot of materials, especially one with rare-earth elements.
Its also easy if you have simple geometries: you can be antiparallel to all of your neighbours in a chain, or on a square (or cube) but what about in a triangle? https://t.co/OM8Zped11j
The triangle has two possibilities, depending on whether the little atomic magnets are free to rotate or not - we call this magnetic anisotropy, and it basically is just about whether there is a cost to change your direction and how large is that cost.
When that cost is low, we get this, and everyone is happy. https://t.co/SC9Qo1aurk
When the cost is high - when the atomic magnets can only point in a single direction and be either up or down, there is actually no nice solution at all! We call this kind of system geometrically frustrated. https://t.co/R0ZiQG6NPQ
Although the atomic magnetic moments, and the interactions between them, i have talked about so far are of course a consequence of quantum mechanics, all of the above you can understand by treating the magnetic moments as being classical objects.
When we get into quantum magnetism a bit later today, things will get much weirder https://t.co/eXDJjoAtXi
@schrodingerskit Dont make me do a thread on Russel Saunders coupling 😅
@schrodingerskit All the answers to this question and more: https://t.co/HH1GVycnfx
@schrodingerskit I'm pretty sure that the magnetic fields due to the spins in the magnet induce actual current loops in the metal of the fridge. Based on which metals (cobalt and iron) do work vs which (gold, copper, aluminium) dont work...
@schrodingerskit It's less about how good the metal is than it is about how high is the magnetic susceptibility of the metal. Both cobalt and iron are soft magnets at room temp, so you can induce a large magnetic moment in them with a magnetic field.
@schrodingerskit So this means it's less about the magnetic field due to the induced currents (which is stronger for a better metal) than it is about aligning the spins in the metal of the fridge
Alright, its time to get weird! https://t.co/qPQeqkloBC
Unfortunately, we have to get a *bit* mathy here, but I will try to do this as nicely as possible. In the classical world, we had two atoms which had a bar magnet each, and that bar magnet could point essentially anywhere. In the language of math, these are vectors. https://t.co/9dQL4C0xpX
The equation that determines how these will behave is the Hamiltonian, which is an equation that tells you the energy of a system. The lowest energy state is what we call the ground state, and is where we would find the system at zero temperature. https://t.co/L6DRSnBK6L
The simplest classical Hamiltonian that describes what our atomic magnets will do is this one: It just considers a pair of atoms, treats them like a vector, and wants to know what their dot product is (if you need a quick refresher on what that is, now is the time!) https://t.co/vpNKkavyZ0
Based on whether J is positive or negative, the lowest energy will be when the atomic magnets are either aligned or antialigned, which are the two simple cases from before. J is usually something we would measure, because its very hard to calculate just from quantum mechanics. https://t.co/VLZ826F8Kd
What really defines quantum mechanics is that things are quantised. Crazy, right? In the case of our atomic magnets, this means (and ill call them spins now) that they cant point in any direction, they can only point in certain directions separated by a small jump. https://t.co/diT1ShF7Mi
We are going to consider the simplest, and most quantum case, where "spin" has a maximum value of 1/2, must also have a minimum value of -1/2, and since it can only change by 1 each time, it has no other values. Conveniently this means i can say its pointing up or down ;) https://t.co/H0t3r2pZiR
Another consequence of us being in the quantum world is that the equation we were using before is busted. You cant use an equation based on vectors any more! Vectors have to be replaced by these things called operators, but thankfully i can just show you what they do: https://t.co/5jPrrIes1r
each of the operators, when it acts on a spin, gives you something back. the Z operator gives you the spin back, but + and - flip the spin. If the + operator tries to flip an up spin up, nothing happens. if the + operator tries to flip a down spin up, you get an up spin. https://t.co/GT8qmDpbvn
Another small caveat is that these operators care about who they are operating on! So where the equation above reads i and i+1, this refers so the atom on the left or the right in our picture with just two atoms. https://t.co/p9OF4v7iCy
So, now we have to consider two cases: J is positive, and J is negative. For J > 0 we try our regular solution before, and it gives us our trial back times its energy. https://t.co/AbDbBO6ZR4
Thats great! Thats exactly what quantum mechanics requires. https://t.co/ZOZtg3zJjL
For the solution where the spins are antialigned though, something funny happens. https://t.co/mO1vpZ992g
It just flips our spins! This means that what is a solution in the classical case, is NOT a solution in the quantum case. Because the quantum world is radical, we can try other things as solutions and see if they work. The most radical solution of all is this: https://t.co/md5vs5NbcT
What we have done, is taken the quantum superposition of two different, but equally valid classical solutions, and somehow this turns out to be the right answer! But, is it still even a magnet? https://t.co/ScWnmrvhNz
The answer is tricky, but basically: not really. This superposition takes a magnet pointing in one direction, and entangles it with a magnet pointing in the opposite direction. The superposition has to average everything out to zero, so quantum mechanics has turned off magnetism!
This is just for two atoms though. What if we had a more realistic situation, like a chain, here we see a problem... How did we choose which atoms to pair?? https://t.co/grXbYjsFGs
You know theres only one way we can possibly resolve this ambiguity fairly. SUPERIMPOSE THEM BOTH! [evil laugh, lightning] https://t.co/Ugbf4QWKqX
This madness continues, of course, if you have atoms arranged on a lattice (like a crystal) instead of a slightly artificial chain https://t.co/b9N2S92f8w
In the end the description is very hard, because the object we call the groundstate is the superposition of VERY many different states which are themselves made up of a lot of superpositions. https://t.co/FNiMPFsRLB
But what actually is this crazy thing that ive spent a hundred tweets building towards? https://t.co/s4h4aE5qal
We call this a Spin Liquid. It is, really, a giant quantum soup of spins which is very chaotic even at low temperatures (near absolute zero). It is a challenge to describe, but its also a big challenge to measure! Trying to measure and understand these is an ongoing problem. https://t.co/5pv6NMsBoh
I hope you made it to the end, because if you did you now know something about condensed matter physics and magnetism that most people would graduate a physics degree without knowing!
@NotHF That picture is actually ectoplasm from Ghost Busters 2, sadly spin liquids are nowhere near that cool! It's an example of a state of matter that can only exist parasitically on something else. Like a metal, or a magnet, they need a regular solid (or rarely liquid).
@NotHF Most known spin liquids are based on copper, but the chemical formula are dizzyingly complex. There are some naturally occurring examples, one of which is the mineral Herbersmithite. It's also one of the prettiest!
@C_J_Smith 😘
@NotHF Some do! Its not a generic feature though. Some also order at very low temperatures due to nuclear spins, impurities, or other subtle effects and interactions. It's quite a fragile state.
@NotHF My pleasure! Will try live tweeting a condensed matter conference tomorrow so there will be quite a few future tweets about weird magnetic states 😅
@Foreman1David Thanks! I forgot to sub tweet myself with something similar :p
Today, less than 20 hours after getting home from my transatlantic trip, I am off again to the first of two conferences I attend this week. https://t.co/XaEfDPzaBr
As I leave the house 10 minutes later than planned (as is tradition) let me tell you a bit about travel as an academic in my field. https://t.co/GDNzIQeiXm
I do, sometimes, a LOT of travel for my work. In a really busy year I might make as many as 10 overseas trips and several ones within the UK. This can take a toll. https://t.co/mid4NUnhDF
This is especially a problem for someone like me who is very disorganised. In the last 5 years I have missed two flights due to being late (booked the wrong airport coach and was simply caught in traffic), forgotten my passport, and booked flights on the wrong day several times. https://t.co/aYpBHKIj3q
In some cases I am *very* lucky and work pays for these mistakes. In other cases, I am severely out of pocket (usually because I'm on holiday and trying to get back for a work event like an experiment or conference, a happened this week)
This is separate to social and emotional costs, like how often I go on holiday with my friends and partner but have to leave early because I have an experiment scheduled https://t.co/EZJR2BEMaX
In scattering physics, your experiments are a big deal - you have to go to a major facility and you get a certain number of days between 1 and ~10 to do your experiment. You applied to do this work competitively, and you have probably waited 6 months for this to happen... https://t.co/2DoSRRlU5U
And when I say days, I mean that literally. Your 6 day experiment is them giving you part of the instrument for 144 hours and if you dont have a big team, say goodbye to your sleep patterns! You also dont get much say in when these experiments are scheduled. https://t.co/yjxkVCy0jt
So I often find myself sneaking off during term time, carrying a big stack of marking, ready to teach the day that I crawl home however shattered I might be. https://t.co/tsIeeWrFlc
This, combined with international flights, means i cannot recommend Melatonin tablets highly enough. It is MAGICAL for adjusting your circadian rhythm and helping to mitigate jetlag or coping with night shifts. https://t.co/NgHaE1gSiH
So, I should finish by saying conferences are great fun, and experimental are the lifeblood of science, but they can extract a heavy toll! Especially if you require childcare, or you cant/dont want to leave your partner or a family member for too long.
If you were interested in what I had to say about magnetism yesterday, here is a fairly accessible essay about an extremely powerful technique in physics (called Renormalisation) which unites the study of liquids, alloys, and magnets into a single framework. Powerful *and* cool! https://t.co/ve1aYvPRmQ
Sure Majorana Fermions are interesting, but so is Majorana himself - he vanished without a trace at age 32! https://t.co/srCPgK11Wb https://t.co/STNmrZtOeQ
If you were *really* interested by all this and you have a basic knowledge of @MATLAB, I can give you a copy of some Matlab routines that will calculate the properties (energy, susceptibility, correlation length, heat capacity) of the 2D Ising model as a function of temperature.
It also contains a much more exciting routine to so the same calculations for the 2D XY (or magnetic compass) model, the study of which led to the 2016 @NobelPrize in physics! https://t.co/zSI1CFpAuj
It also makes pretty pictures similar to this one: https://t.co/ncmSQpbQLA
@AnsonMackay I bring the real @tigerinstemm energy to my travels 😅
Made it! I missed Professor Seamus Davis' plenary on measuring magnetic monopoly noise in spin ice, but it was a tactical choice so I could catch up on the sleep i missed travelling yesterday, and I've had the opportunity to see Seamus give this talk recently
So first up I get to see a talk on getting magnetism out of nonmagnetic materials! https://t.co/B6S4nmLRD9
It's quite exciting because they are doing the world using metal organic frameworks, which is something I work on in collaboration with @goodwingroupox https://t.co/I8B0rXSqU3
Theres a lot going on, because for starters they are trying to look at something similar to skyrmions, which are a peculiar magnetic phase people are looking at for magnetic memory https://t.co/CxvXgKbzdb
But to make it more exciting/ complex, they are doing it with orbital quadrupoles instead of magnetic dipoles https://t.co/46kpTRhuUa
They have managed to show that these phases can exist theoretically, but are yet to find any systems which realise this experimentally. Its early days yet though! This talk was by Emma Wolpert from @UniofOxford
Next up is the man who had my current position before I did, Dr Paul McClarty of @tudresden_de https://t.co/13FDiqh0Uv
Paul is an incredibly clever theorist, and I definitely cannot so justice to such a complex topic in tweet form, so I'll just tell you what a magnon is!
Remember yesterday we had ferromagnets? https://t.co/RoomAgPtxL
Well we said this is the ground state, which means there are some states which are "excited" states. If we consider our magnet to be fairly classical, these excitations are just wiggles of our atoms, a lot like vibrations
Because what one atomic spin is doing affects what its neighboura are doing, these wiggles move along the crystal, like any other kind of wave in water, air, or a crystal vibration (which is called a phonon btw!) https://t.co/7Fmfzjig7m
These magnets have an energy cost, and a wavelength, and these have a complicated relationship. Ones with a very long wavelength have very low cost because nobody is moving very much. Ones with a short wavelength have a higher cost because the spins are further from home.
This gives you what we in physics call a dispersion, in this case a magnon dispersion! They give you very pretty pictures to show at conferences (cheating because this is data from a much more complex system, but it's one we saw yesterday!) https://t.co/jHzcMu3Mzm
The following talk is also about magnons https://t.co/LzGdPK6jgY https://t.co/QV4o1g2nm9
The kind of magnons I showed you before are what we call transverse magnons. This means that the direction the magnetic moments wobble in is perpendicular to the direction they point in.
The current case being talked about by Harry Keen from @uniofedinburgh is that of longitudinal fluctuations: this means that instead of wobbling around their axis, the spins fluctuate in size in a way that is correlated with their neighbours.
We normally ignore this, because in a lot of materials this costs far more energy than the system has access to (generally that is set by the temperature). But there is a case where it's very important: magnetic metals!
Side note, it was awesome to see someone cite a classic book in their talk. Importantly one that I own! https://t.co/1FeE3QhiJ5
Understanding magnetism in metals is actually very hard. The framework we used yesterday doesnt work well - you might get something that behaves similarly, but all the numbers are wrong and you can see some behaviour (like longtitudinal magnons) that you wont see in insulators.
Now it's time for a talk from an old labmate of mine, Dr Matt Watson who has recently moved to @DiamondLightSou https://t.co/dTvfMZoZFK
Matt's work focuses on very thin magnets, sometimes even only a few atoms thick! Thats quite thin https://t.co/1Q9fJpSIVe
He is working on CrGeTe3, a material which has a honeycomb of Chromium atoms in its crystal structure that give rise to its magnetic properties https://t.co/J6xXeMRl48
Matt does a technique called Angular Resolved Photoemission Spectroscopy or ARPES, which basically uses the photoelectric effect to kick electrons out of a material and studies the energy and momentum of these electrons https://t.co/Apjxn29Qrx
@MySci_PK @GrapheneCA @GrapheneLabs @2DResearch @MyGraphene I thought you could use sticky tape? ;p
Here they see some really interesting results: while normally you expect the behaviour of electrons to be fairly unaffected by the magnetism (it's an insulator, these energy scales are fairly different), but instead they find the chromium electrons to change dramatically!
The energy levels and the lifetimes of the chromium electrons are completely changed when the material becomes magnetic. Magnetism is a very low energy phenomenon (most things become magnetic below room temperature) but metallicity is a very high energy behaviour.
It's a bit like you walking into an office block changing the very shape of the whole building!
Now theres a talk from my colleague Dr Pascal Manuel at @isisneutronmuon Ans he is talking about spin liquids! https://t.co/LJFP0Sk5UI
Most spin liquids, he reminds us, exist in systems that have triangular arrangements of atoms. This is because spin liquids are very delicate, and the triangular lattice is very good at preventing a normal magnetic order from occurring https://t.co/aQ74YBnO2Q
Something which is very important about the material he is studying: NaYbO2, is that the crystals are very perfect. Even 0.1% of chemical impurity or disorder can wash out or even kill your spin liquid, and in some materials this just isnt possible to avoid https://t.co/bPcaxPMJYa
This work had used a lot of different techniques because spin liquids are really tricky to understand: neutron and xray diffraction, neutron spectroscopy, heat capacity, and muon spin rotation.
And heres the money shot, they observe only diffuse excitations showing conclusively that theres no proper magnetic order, the excitations have no gap - I.e. there are excitations which cost no energy, and this is a really nice result! https://t.co/ENR2k1akyP
This is kind of how you look at spin liquids though. You measure EVERYTHING, and spin liquids are a weird amorphous blob that exists only in the absence of anything else.
We now have Johnathan Bulled, also from @UniofOxford He is talking about Frustrated metal-organic magnets https://t.co/liaS3W7Yhm
The magnet Johnathan is looking at doesnt become magnetic till a VERY low temperature: 0.2 degrees Kelvin! That's -272.95 degrees C or -459.3 F for people using freedom units :p https://t.co/X8UyDWW0Cs
What makes this material really cool (hah) is that because of the the magnetism is very frustrated there is a lot of entropy associated with it. This means that if you play with a magnetic field, you can use it like a magnetic refrigerator - the magnetocalorcic effect!
And now we break for lunch!
First up after lunch is Dr Neil Wilson from @warwickuni walking about layers of 2D materials and their electronic properties. https://t.co/XhoVZmr4mD
It's quite interesting that even though the layers are 2D and dont really fork chemical bonds, stacking layers of graphene on top of each other fundamentally changed their properties, even within the layer. https://t.co/ilEFyRPcHR
Some of the interesting changes of the properties when you stack layers on top of each other are due to complicated processes that essentially amount to quantum tunneling of electrons from one layer to another. https://t.co/vjBNkRRtXs
Neil is also using ARPES to measure the electronic properties of these materials (mainly WSe2) It's a great technique for looking at what the electrons are doing, but it requires ultra high purity samples, in an ultra high vacuum, prepared meticulously to get good results.
They have obtained a lot of really exciting results from examining what happens if you change the number of layers that are stacked on top of each other. Remember, each layer is only about one atom thick!
The experimental are also supported by quantum mechanical calculations performed on supercomputers https://t.co/tIUP2bsPf4
The main thing they have found is that the effects strongly depend on how the layers are aligned relative to each other, which thankfully they are able to control to better than 0.5 degrees. In graphene this has resulted in an explosion of exciting results btw!
You can probably guess why if you look at the Moire pattern formed by stacking two sheets of graphene on top of each other with a slightly different alignment: https://t.co/WRDDTFPTpv
Even though graphene is (to me, anyway) quite boring, the twisted bilayers have shown magnetism, superconductivity, insulating and metallic behaviour. It's really crazy.
@MySci_PK @warwickuni Not that I know of, they arent that savvy! Tomorrow has one though :p
As will I, so apologies for everyone following both of us! #LGBTSTEMinar20 https://t.co/DsSUkKTCYw
We have another talk on layers of graphene now, from Glenn Wagner of @UniofOxford who is a theorist. https://t.co/UANelq0edL
He is looking at what mechanism give rise to the scattering of electrons in this material. This is based on comparing his simulations to data, and his equations are a quantum version of the Boltzmann Equation https://t.co/Z9xsqt1ThD
They are able to show using a very clever analysis that the sub-dominant contribution to the scattering is due to phonons (vibrations in a crystal) ruling out other options. They then are able to model the electrical properties as the motion of two fluids: one made of electrons https://t.co/A8vkvNBEmb
And one made of holes! Holes are a concept we have in physics that describes the absence of an electron. It nevertheless behaves a lot like an electron with positive charge.
So this means that the dominant scattering is electrostatic and basically is down to the scattering of an electron fluid and a hole fluid.
Next up we have Dr Marcin Mucha-Kruczynski from @UniofBath talking about those amazing patterns you get from stacking two layers of graphene! https://t.co/YZiju4SUzW
Moiré patterns are really fascinating generally! https://t.co/sMZ6mOjqjH https://t.co/jICHQ66vhm
In this case the effect is to trick the electrons into thinking they are in a different crystal than the kind they really are. https://t.co/a5jy0P1EB3
Because the crystal symmetry has a strong effect on the properties of the electrons and the way they move, this is why the formation of these patterns has a spectacular effect on the way the electrons behave! https://t.co/vH7b2lw2Ua
The late afternoon session begins with a topic which is very big here in @BristolUni - high temperature superconductors! This talk will be by Professor Ted Forgan, head of condensed matter here https://t.co/cNMZnbDcGJ
Superconductors are pretty amazing things- conducting electricity without resistance, expelling magnetic fields, and my favourite related effect: magnetic levitation https://t.co/AHujZgrOGa
Superconductivity is pretty amazing, because before we understood really how it works, we still understood that it was caused by two electrons forming a pair that then conducts electricity without resistance.
Now, given that electrons are negatively charged they should repel each other, so how could they become paired together? The surprising answer that won the 1972 nobel prize is that they are glued together by crystal vibrations! https://t.co/cdJEtNFE1H
The way this works is a bit funny - a negatively charged electron moves along, and disturbs the positively charged atoms of the crystal. These disturbed atoms then attract a nearby electron, and it results in an effective attraction between the electrons. https://t.co/LuX1Cf0XGd
This only works up to a point though. The normal superconductors only really work up to about 45 degrees above absolute zero, or -230 Celsius. Not very practical! https://t.co/D6tuonuSD8
Thankfully we then discovered high temperature superconductors, which are complex and usually based on copper or iron. These can superconduct up to much more useful temperatures and form the basis for hospital MRIs https://t.co/hWiA9KAmQh
The reason they work at a much higher temperature is because the glue between the electrons is not provided by crystal vibrations but instead by magnetism - the magnons which I spoke about earlier https://t.co/yLyVkhbrwc
We have, however, recently made some new superconductors using ultra-high-pressure methods (and they only exist at high pressures!) based on hydrogen. https://t.co/HEPzlgOR0w
These are again based on vibrations to provide the pairing of electrons, but because the energy of the hydrogen vibrations is so high, they work almost at room temperature (just, not at room pressure 😭)
Next up is Dr Alexander Petsch who is also from @UniBrisPhysics talking about the importance of charge density waves in high temperature superconductors https://t.co/d3HvqpdFTf
@NotHF It was a very pedagogical talk, but unfortunately quite brief so it would have been hard to follow for the uninitiated! https://t.co/6jwZsYdRKh
Charge density waves are an unusual feature exhibited by some insulating materials, where the density of electrons varies in some direction of the crystal. https://t.co/7k25DoLT7M
A simple example of this might be an element like Cr which can be 2+ or 3+, but in Cr3O4 the average number of electrons per chromium is 2.666. There are many ways this could work out in practice, because each chromium in an insulator needs an integer number of electrons
The charge density wave solution might have a pattern where the chromium atoms went 3 - 3 - 2 - 3 - 3 -2 - 3 - 3 - 2 The crystal symmetry would be different here than if the arangement was simply random, because the symmetry cares about what each chromium is doing!
Now we have Dr Adrien Gourgout from University if Sherbrooke https://t.co/l0AmBCeXEo
It's been a long day and I can barely explain a fermi surface to my undergrads 😅😅 So how about we chat about the thermoelectric effect? https://t.co/dHGKAuxTtm
When you run a current through a resistor it gets hot, that's quite a common observation. But did you know that if you make one end of a material hot and the other cold, a voltage is built up? You can exploit this to generate a current. https://t.co/PmkBo25cSN
I always find this super cool, and it's actually the basis for some types of power generation and for heating/cooling when you want to avoid having any moving parts.
RT @MySci_PK: This might be a long shot but here goes nothing. I am looking for materials/nano scientists working in the field of agricul…
RT @MySci_PK: I am looking for materials/nano scientists working in the field of TEXTILES. Who will take over @realsci_nano for a week. h…
Next we hear from Dr Carolina de Almeida Marques from @univofstandrews https://t.co/WDSwWQI8xo
Nematicity is a fascinating property of some liquids, which is responsible for giving us liquid crystal displays! https://t.co/SBxKM0q2jZ
What this means is that under some conditions, the molecules in the liquid will go from isotropic (randomly aligned) to nematic, or aligned. https://t.co/6mWZEeMAEZ
How does this apply to a rock of something like Sr2RuO4? The electrons! They are liquid-like enough that under certain conditions they lose the ability to flow freely in all directions, and this is called a nematic phase
Next up is a theory talk from Swagata Acharya @KCL_Physics https://t.co/3WE3y0zmnS
He has been funded to do work using the Questaal package which is a pretty amazing sounding open source code for solving condensed matter problems https://t.co/VkMIeP502b
And that's a wrap! Unfortunately I have to miss the second day of this conference and get on a train to Birmingham but the upside of that is that it's all so I can attend the 2020 LGBT STEMinar tomorrow! So tune in tomorrow for a lot more science! #LGBTSTEMinar20 https://t.co/y9bxALlh2X
@ProfRachelGaN I can say my favourite formal definitions and some vague things about what it represents but that's all 😅
@sandykilla Any time 😅
I've finally arrived also! It's on the opposite side of campus to where I arrived 😅 https://t.co/xBs3LaNjdn https://t.co/8eGNpnImcd
We are now beginning with an address from @unibirmingham deputy pro-VC of equality, diversity and inclusion #LGBTSTEMinar20 #LGBTQScience https://t.co/pZIKKXm39G
Professor Jo Duberly reminds us that this is the *fifth* LGBT STEMinar, and although we have made great strides in visibility and inclusion in STEM in the last 5 years, a lot of work still remains to be done.
And a moment to thank our sponsors! <3 #LGBTSTEMinar20 https://t.co/5rSNVvbnFy
The opening plenary of #LGBTSTEMinar20 is being given by @MarinaLogares talking about LGBTQ+ visibility. It's so awesome to see such an accomplished and senior out figure in a field like mathematics! https://t.co/36AM7UnwHi https://t.co/FxqBySFf4t
She talks about the importance of visibility and how we have made great improvements in this area, but that it's still very difficult being open with colleagues Also she is organising her own STEMinar in spain in november 2020!
Her area of mathematical physics is algebraic geometry, which is quite complex 😅 https://t.co/JTNNHiuuEw
But she is mainly here to talk to us about what it means to be a scientist who is both LGBT and a woman, because normally when you search google for "top scientist" all you get is this: https://t.co/sxfYDYrHn5
Why is diversity important? Well, aside from the principle that everyone deserves a fair go, it turns out that diverse groups perform better: https://t.co/LUxoH0xP7I
@Foreman1David https://t.co/8YMIZxAMM1
@Foreman1David https://t.co/aUzhICNX4c
There are some positives: the majority of scientists feel able to be out at the work. But in news that is probably not surprising, the more women are in a discipline, the more comfortable LGBT people feel there. https://t.co/288TO8y81I
In case it wasnt clear what an amazing person Marina is at this point: https://t.co/1IhWUaf4j1
@Foreman1David Theres some work I've seen that I can dig up later which suggests, at least in one specific case, that more diverse teams produce socially better outcomes in machine learning work (more likely to consider ethical implications, etc).
Next up for the #LGBTSTEMinar20 @NathanWoodling is going to tell us about how fruit flies can be used to tell us about the biology of ageing and dementia. https://t.co/spDFdmqlf3 https://t.co/efkcyQG3vJ
Nathan is, it turns out, quite the artist https://t.co/kNOl8W4U8E
There is quite a lot of evidence that certain genes are linked to ageing, and that mutations in those Gene's can often lead to increased lifespan. In some simple animals mutating a single gene can double their lifespan! Even in human populations there is evidence for this.
@NathanWoodling quite likes flies as a model organism because they are complex enough to have a full anatomy similar to humans (heart, brain, digestive system, etc) but they only live a very short time. And wings. They have wings. (Personally I think the eyes is the killer) https://t.co/nDYSgSdDNo
He also has to perform a lot of brain surgery on teeny tiny fly brains https://t.co/qSIhFBkXf7
Part of his research involves comparing genes which are involved in ageing in both flies and mice, and making sure those genes change in the same way, then testing what happens if you modify those genes one at a time in flies. https://t.co/ay4GxNRvok
What he wants us to take away is that the same genes seem to be involved in ageing are similar across many animals, and that changing just one single gene can increase healthy lifespan in some cases!
He also wants to remind us that having to do a PhD on the opposite side of the world to your partner can be very hard! Especially when the country you're in does not support your relationship at all. But his story has a happy ending! https://t.co/pu1kJJimaD
Now at the #LGBTSTEMinar20 we hear from @DoriekeMG is going to tell us about how our brain connects our knowledge of landmarks to our understanding of where we are. https://t.co/d1JoEyeSPM
There are certain cells that activate in our brain only when we are in a specific place! And because scientists are amazing at naming, those are called Place Cella https://t.co/lmxBp8UDzF
@DoriekeMG puts mice into an amazing little virtual reality program and studies the activation of these brain cells vs where the mouse is inside the virtual environment. https://t.co/PcMF88VGVU
The results on the mice are quite counterintuitive though, because although the mice improved at the task they were given, the cells did not behave as expected.
Final talk of the #LGBTSTEMinar20 morning seminar is Marcus Lohr talking about astrophysics https://t.co/zgjrruzpZ1
In particular Marcus is going to talk about massive stars https://t.co/mfMUE8sKd1
Specifically stars within the Arches cluster in the milky way galaxy https://t.co/ZQhpwRL4Af https://t.co/H0q6I8UcH5
This is of interest because it contains a high density of massive stars, and in particular binary massive stars. We want to understand these because they will eventually lead to the binary black hole mergers we have recently observed using gravitational waves.
Nearly a third of all the observed targets in the survey met criteria that suggests they are binary stars. Thats a lot! https://t.co/7ZW6txQ7hL
In the future Marcus will turn their giant telescope and scientific powers to study the Quintuplet cluster https://t.co/P9Y6tG4HJ9 https://t.co/ZfJTRKfpRc
First up to talk at the #LGBTSTEMinar20 after the morning break is @Sunkensie to tell us about simulating the impact of plant levels on waterways https://t.co/aWRQMltdvU
This is important because river vegetation has a profound impact on flooding, which has increased in frequency and intensity in the UK in recent years https://t.co/sUum938f7f
"Here is what a plant looks like in case you didnt know" https://t.co/CiOhERkvH2
@Sunkensie's research, which uses a sophisticated 3D model of the effect of vegetation on water flow indicates that the plant coverage has a huge impact on the water flows. This has big implications for flooding in the future https://t.co/WXZf7zhVLu
Climate change is expected to cause the amount of water plants to peak later in the year, to coincide with autumn storms, which will create a feedback loop of worsening flooding (Aligators not included) https://t.co/lQoQH7O04A
Unfortunately the answer is not just more or less plants. Fewer plants near settlements will decrease flood risk locally, but that just means worse flooding downstream.
Now we have @Tuffers_c who is both gay and northern 😅 They will be talking to us about the origins of misalignment between stars and planets. https://t.co/FA4HQJM98n
The way solar systems form normally, is why all if the planets are in the same plane, and that's the plane that the sun rotates in also. https://t.co/Ype5aocpnX
But thanks to deep space imaging like Kepler, we now know that not all solar systems are like this. Some of them are... a bit wonky. https://t.co/hnkDLZtXaW
There are a few ways this is thought to happen: the star shits alignment after the disk that will eventually become planets has formed. Something happens to a planet that changes its axis. Or the disk forms in a completely unusual way.
The data for the alignment between stars and its planetary orbits is quite sparse, because it is hard to measure and may take decades of observation. There are only 15 extrasolar systems characterised properly.
Statistical analysis indicates that the number of misaligned systems may not be unusual, but their degree of misalignment is very difficult to understand.
@beka_valentine Its genuinely painful that we have to use "added value" to justify inclusion, but some people refuse to listen otherwise
@CanopyRobin with the best flash talk of the session: "TREES" https://t.co/y45F2PpcMM
And now its lunchtime for the hungry folks of the #LGBTSTEMinar20 https://t.co/ikEd3zbthE
@sassyscience_ @drclairemurray @PRISMAciencia @MarinaLogares Oh I tried to find their twitter handle earlier and couldn't. Thanks for tagging them!
@jamgregory I'm too tense to eat much 😅😅😅
First up after lunch at the #LGBTSTEMinar20 is an address from Professor Tim Softley FRS, the PVC of research @unibirmingham affirming that the new british government will commit us to a strong investment in scientific endeavour, to uproarious laughter and applause.
Now we have a talk on autophagy and motor neurone disease, which I am glad we have after lunch, given by @mattjaywhy #LGBTSTEMinar20 https://t.co/ZwP7JN92qw
MND or ALS is a terrible disease. Famously Professor Stephen Hawking suffered from it, but he was very lucky - he lived 55 years after his diagnosis which is far longer than most. https://t.co/Y7kC8zmlwJ
@JostMigenda We needed the laugh 😅
Neurons are also wild. And somehow, huge! The nerve fibres called Axons may stretch the whole length of the body https://t.co/djms6dRTKC
Neurons are very large and long-lived cells. Autophagy is the process whereby cells eat some of the broken parts or bits which arent necessary anymore. Neurons therefore have an important balance between growing new parts and eating old or broken parts https://t.co/W32SJtCjcn
When the balance is broken, and autophagy happens too much or in the wrong way, this can lead to diseases that affect the brain, especially ones like Motor Neurone Disease
It's also a problem when you turn off autophagy! This can lead to neurons growing too long, which leads to other disorders.
Now the #LGBTSTEMinar20 gets some supersymmetey from @GeeknProud42 https://t.co/WkNgseuJzA
@MarinaLogares @PRISMAciencia Sorry! This is what I thought might be the case but I was in a rush 😅
Important note: this talk is making use of text-to-speech technology, and we had a brief technical glitch setting it up but now it's working great. A question for conference organisers: would your conference be able to support this?
The standard model has 3 generations of fermionic particles, force carrying bosons, and the higgs. https://t.co/sx8awZDijW
Gluons are some of the most important, because they bind quarks together into protons and neutrons and hence atoms. And are not to be confused with some warlike races from the star trek universe https://t.co/fCHNvrhe5Z
But the standard model has to be incomplete, because it seems to account for only 5% of the universe, there is seemingly a lot of missing energy and matter. It also cannot explain why we are all made of regular matter and there isnt really any antimatter floating around. https://t.co/tgctWnWtJB
Supersymmetry is a model which might solve some of these problems. It posits the existence of a super-partner particle for every known particle, which is almost the same as every particle but much heavier. https://t.co/svExbIU1BS
They also have TERRIBLE names. For every particle there is a supersymmetric sparticle. For the quarks, their super-partners are the squarks, and for the top quark, there is the stop quark. https://t.co/QsssmqUS0B
Many people hope that this would provide a complete picture of the universe, because if it isnt, we should all give up and go to the pub 😅 https://t.co/YopamuPU5T
The final talk of this post lunch session at #LGBTSTEMinar20 is from Jon Davies talking about the variation of gene regulation in brain development and autism spectrum disorder https://t.co/1TbkluR2f4
This talk is mainly about the phenomenon of epigenetics. If genetics is the blueprint, epigenetics is the person reading the blueprint to build an ikea table but maybe sometimes making it into a bookshelf. https://t.co/IwTnaEVAQz
All of your cells have the same genes, but epigenetics is what determines whether a stem cell becomes a muscle cell, or a skin cell, or a brain cell, etc. This is important because twins have the same genes, but in 70% with autism spectrum disorder of twins only one has it
This means there must be an epigenetic component. If it was just down to your genes, then it would always be both or neither. This is actually true of many diseases and conditions which are known to have a genetic component.
Terrifying takeaway from this talk: by examining your genes people can tell if you have smoked, drunk alcohol, or taken drugs. They leave a permanent mark on your body which is part of your epigenetics!
@jamgregory It's just the anticipation. I think also the live tweeting is getting to me!
RT @PrideinSTEM: Wanna know more about us? Wanna get your hands on one of the incredible @LGBT_Physics stickers? Wanna ask @DrCarpineti any…
@jamgregory https://t.co/L2GjMl9xTm
Now we break the #LGBTSTEMinar20 into two parallel sessions. I will be in the session "creating and running LGBTQ+ STEMM Networks" cohosted by @PRISMexeter and @Birminghamostem
After the breakout panel we have @GayRollerCEng giving us the lowdown on the nuclear robots she builds today at the #LGBTSTEMinar20 https://t.co/K7HqXzbmEi
These robots are meant to assist in fusion power plants, like the tokamak under construction at ITER https://t.co/Bd9oXeoS1H
The heat involved in fusion power is immense, the plasma is about 15 million degrees. This is wrapped in coils of superconducting magnets at -270 degrees. That's quite a huge difference! https://t.co/TjLXEC7W53
It's difficult enough containing that heat, but fusion also produces a lot of neutrons. When neutrons smash into materials, they dont just make them radioactive, they leave behind damage at the atomic level which makes the material brittle https://t.co/gXUwz384hi
Theres also a lot of radiation flying around. Radiation is usually pretty bad 😅 https://t.co/RGzQue0UKe
As a result of all this radiation, we would like to use robots to do work inside the fusion reactors! https://t.co/I75daZClXj
These robots need to be able lift 80 tonnes, be incredibly precise, and all their parts need to be easily replaceable.
Basically: It's really hard! https://t.co/OAn101qt2X
But its worth it. For the amount of lithium in your phone battery, and a bathtub full of seawater, you could have power for 40 years. It's also quite safe! Fusion power plants basically just stop working when they go wrong. They safely turn off. https://t.co/l1VOB53TUH
Why do we not have fusion yet? Mostly money. ITER will cost about 20 billion, and if we spent more we could have it faster. For reference the soccer world cup in Quatar will cost 150 billion. https://t.co/11ULb8k6Ql
Also @GayRollerCEng is REALLY funny. https://t.co/0xfA2sm5o4
The final talk of the day for the #LGBTSTEMinar20 is by @Dr_KTaylor talking about the relationship between HIV and a heart disease https://t.co/07DyEBwJBk
It is quite difficult for people of my generation and later to really understand what it was like living through the epidemic of the early 80s. It's also impossible to overstate the importance of activism in forcing action on the epidemic from the establishment https://t.co/OZH1vjnPo8
It's also amazing to note that almost half of all people diagnosed with HIV are women, despite the association with gay men. Although this ignorance around infections in women led to the phrase "women dont get aids, they just die from it"
The world has moved on greatly from this. We now have PrEP, PEP, and antiretrovirals that enable people to avoid infection or live a normal lifespan once infected. However, antiretrovirals are associated with an increased risk of heart failure.
In order to avoid complicating lifestyle factors, @Dr_KTaylor studies blood of people who do not have HIV and how antiretroviral drugs affect blood clotting. Knowing these effects would enable therapies to be tailored to avoid damaging heard health.
Additionally thanks to these medications (undetectable = untransmissible, and PrEP preventing infections) we are on the verge of ending the HIV epidemic
And now @TheLabAndField is here to wrap up the conference https://t.co/fja52k9Rka
And to announce that @ClaraMBarker and I will be hosting this conference next year at @wadhamoxford @UniofOxford But mostly we need to thank @TyLKelly for doing such a great job hosting this years #LGBTSTEMinar20!!!
@kizzythechemist @ClaraMBarker @ProfRachelGaN @wadhamoxford @UniofOxford @TyLKelly Would providing accommodation overnight so you can come up the day before and recover help?
@kizzythechemist @ClaraMBarker @ProfRachelGaN @wadhamoxford @UniofOxford @TyLKelly Forgot how incredibly long that journey is 🤦♂️
It's the end of my week curating @RealSci_Nano so I would like to thank everyone who read or interacted with my tweets, it was intense but very fun! If you ever have questions about physics, Crystals, magnetism, or LGBT issues, feel free to get in touch with me @AJPrincep
[admin] Thank you Andrew (@AJPrincep ) for a wonderful week and great start of 2020. Podcast interview of Andrew and more - https://t.co/fh00JdUPX9
Kerstin Göpfrich
[admin] DNA origami: building synthetic cells Please welcome this week’s curator - @KGoepfrich Podcast interview - https://t.co/tfa1lZclFd https://t.co/q5W6kt1lfU
Hi all, this week I am here @RealSci_nano!
RT @KMothPoulsen: We currently have 14 open fully funded PhD positions, in the area of Nano @chalmersuniv Please spread the word. 😀😀😀 #phdc…
What should we talk about? My suggestions:
Sunday - Who I am, what scientists do on Sundays Monday- Building a synthetic cell Tuesday - Starting a group, research in Germany Wednesday - What's going on in the lab: DNA origami Thursday - The challenges Friday - Communicating science as a scientist Sat - How to pick a lab
But let me know what you are interested in!
@Charlesthornt @realscientists @KGoepfrich Cool! Any questions or comments?
What do scientists do on a Sunday morning? Definitely sleep in! This is why it was so quiet here.
@Charlesthornt @realscientists @KGoepfrich You are right - in synthetic biology, there are 2 streams: Bottom-up and top-down. The top-down approach is about manipulating living cells (e.g. by genetic engineering, like @JCVenter).
@Charlesthornt @realscientists @KGoepfrich @JCVenter Bottom-up is about taking molecular components and assembling them to build a cell from skratch (which remains unachieved)
@KMothPoulsen @Felgraf_Physics @chalmersuniv True, that's a great option. Let me know if you have any questions, happy to help.
@Charlesthornt @realscientists @KGoepfrich @JCVenter So true, not yet! But unlike early Earth, we have a defined goal. That will hopefully speed things up in the lab.
Let me introduce myself: I am curious about fundamental questions in science and fascinated by the idea to engineer a cell from scratch.
@KGoepfrich @mpi_mr_hd Previously, as a Skłodowska-Curie Fellow @MSCActions in Stuttgart, I worked on bottom-up synthetic biology and microfluidics with Joachim Spatz.
Previously, as a Skłodowska-Curie Fellow @MSCActions in Stuttgart, I worked on bottom-up synthetic biology and microfluidics with Joachim Spatz.
Now, since Nov. 19, am am leading the Biophysical Engineering Group @mpi_mr_hd https://t.co/2Jg77KUgkN
Exciting start of the day: Our group has a new member!
@KGoepfrich Bottom-up synthetic biology follows the vision to engineer a cell from skratch, form molecular constituents. A bit like recombining the pieces of a puzzle. https://t.co/5QUvllZ9xv
RT @RealSci_Nano: @KGoepfrich Bottom-up synthetic biology follows the vision to engineer a cell from skratch, form molecular constituents.…
When building synthetic cells, we need tools to assemble the components. And I believe that microfluidics is a great tool. Why? Check out this video I made: https://t.co/omq5lDDUOP
Oh, by the way - anyone researching agriculture? We want you on this account! https://t.co/W42VF8fhn4
@MySci_PK @mimimibe Fun fact: I used to work with coconuts. Coconut water contains free-floating cell nuclei that I was inserting into synthetic cells.
@MySci_PK @mimimibe Cooler or more delicious? Here they are! https://t.co/HFSjYtemIP
My PhD hat was rather spectacular, mimicing the large DNA origami nanopore that I built (2017). https://t.co/C9OS7MD65R
PI stands for principle investigator (group leader). When you become a PI, you are confronted with lots of new, mostly fun, challenges. PI water helps (spotted in Japan). https://t.co/t5aD9yps7W
@dani_nightshade I wonder if that is actually the case. Because it says non-ionic below.
DNA origami is about folding DNA. This is how it works: https://t.co/uDrhouiNBW
First of all, good morning! Today is about DNA origami.
[admin] Podcast announcement! “DNA origami - building synthetic cells” The extended conversation with the wonderful @KGoepfrich is available now - https://t.co/tfa1lZclFd https://t.co/3SJn1aHPdY
@GayRollerCEng @i_jayas Take a long single-strand of DNA with a known sequence. Then write down short sequences, which attach at two differen places on the long strand. With this, you are folding the long strand in the desired place.
Soooo, the long version about DNA origami and synthetic cells is out! https://t.co/KxTK3PRwlE
One new scientist in the field of material/nanoscience every week! https://t.co/8Ch1hdfJV6
@GayRollerCEng @i_jayas The answer comes in form of a video: https://t.co/QRhKe2m5f1
@GayRollerCEng @i_jayas DNA origami rulers for superresolution microscopy are already commercially available @GATTAquant. Also other applications are emerging, for instance in the field of synthetic biology and biomedicine.
Any teachers among our followers? You can also invite me (or any of the other scientists) to join one of your classroom lessons via @RingAScientist, live per webcam! Check out https://t.co/NqkUEphiXc
@GayRollerCEng @i_jayas DNA origami is about making molecular shapes, no genes. Its like architecture on the nanoscale. So you cannot change the genes, but you could potentially build a nanoscale robot, that is fixing things inside your cells.
@GayRollerCEng @i_jayas Yes!
@GayRollerCEng @i_jayas Right idea!
Our best friend: https://t.co/h1rgcsat3i
Since we talked about it yesterday: https://t.co/V0Y2EdRpK6
Today in Heidelberg. That is our institute. https://t.co/UU2MSNXEkK
@GayRollerCEng @i_jayas yes, actually you could dissipate a proton gradient with the DNA nanopores.
@i_jayas @GayRollerCEng DNA itself is negatively charged. So when we anchor it in the lipid membrane of a cell, we also introduce charge.
Absolutely! https://t.co/33sS38Ml8z
@JoFeanelwa or to remove the filter from the photo ;-)
Good morning! Just finished skyping with a class of 15 yr olds during their physics lesson via @ringascientist. Now they know why we build synthetic cells!
@RingAScientist Fits well, because today I wanted to talk about scicom. What forms of science communication do you like / have you tried?
@i_jayas @GayRollerCEng Nice! I could also never decide between biology and physics
@i_jayas @GayRollerCEng Yes, we sometimes wrap a lipid membrane around them, or use chemical modification or uncharged DNA analogues (PNA).
@i_jayas @GayRollerCEng But you are right, with the plain DNA the charge can be a problem for some applications
Good morning everyone. My last day here! Any questions that we should discuss?
For those in Heidelberg: https://t.co/pohCRT6Gtw
@Brampton93 Yes! If you look for instance @MaxSynBio, the synthetic biology cluster of the Max Planck Society, ethics groups are included.
@Brampton93 Everything we build is so simple and volatile that a drop of dish soap will destroy it.
@ysumbelli Good question! What takes most time for us is usually to decide on a story line and to make really clear figures. The writing itself is normally rather quick.
@Brampton93 @MaxSynBio I would say there may be cases where individuals don't follow safety rules. That is unethical since it can harm colleagues in the lab.
@Brampton93 @MaxSynBio I can recommend this article on ethical checkpoints for my own field - bottom-up synthetic biology: https://t.co/mM4YVyvFHd…
@MySci_PK @RingAScientist @IndSciComm @iamscicomm Let's make this a collection! @RingAScientist @FameLab @scienceslam What else?
RT @AlexGelle: Interested in training in science communication? Join me and the rest of the @ComSciConCAN team for 3 days of FREE panels…
RT @DimovaLab: Just joined the editorial board team of the Biophysical Journal @BiophysJ in the membranes section (following the lead of gr…
Finally, it is time to say goodbye on this account. I will still be on @KGoepfrich and I am looking forward to continue the discussions.
@KGoepfrich [admin] Join us in thanking @KGoepfric for a wonderful week! 🔬 Podcasts and more - https://t.co/tfa1lZclFd https://t.co/btZey4pUCw
Siva Shakthi
[admin] "Dancing Light at Nanoscale" Please welcome @sivashakthia for optics, nanophotonics and more fun! More about Siva 🎙️ - https://t.co/Ly4IPTyGSy
[admin] Interested in curating this account? Pencil in your details here - https://t.co/NJxqNVFAjw
Hey all! Good evening! I am Siva Shakthi and I will be curating this account this week. I will be talking about the area of nanophotonics - the what, why, and how. I am very excited to be here and let us begin! #nanophotonics https://t.co/z1kKq0YQF9
Let me share a bit about myself before we indulge into the field of nanophotonics. I am a Ph.D. student at Indian Institute of Science Education and Research, Trivandrum, India. I work in the area of microwave photonics. I am not exactly a nanotech person so why am I here?
Microwave Photonics as a field is a convulsion of Photonics and microwave engineering. While I don't tinker with anything at the nanoscale level, the work that I do has applications in nanotechnology. #nanophotonics #microwave #photonics #scicomm
I work of creating proof of concept experiments in the field of Photonics. One primary example is the creation of notch filter for use in satellite communication and RADAR. But I do these experiments with the help of kilometers of optical fibers. https://t.co/9j1WOEOUdv
But if these concepts have to be employed for creating a device for employment in field, then optical fibers cannot be used for they become bulky. Thus there is a need to miniaturize them and thus we go to the nano regime. #nanophotonics #photonics #scicomm
That's a bit about me and I will tell more about myself in the coming days. Now that I have introduced myself, let us see what I have in store for you all today. Well, we will be looking at how the world of nanophotonics emerged and why it is so important? #nanophotonics
In 2k15, we celebrated the international year of light. It marked the anniversary of many great achievements in the field of optics. It was 150 years since Maxwell came up with electromagnetism and 100 years since Einstein's General relativity. #optics #light
We are quite familiar with the way optics work. We use glasses and mirrors on a day to day basis. Phenomena such as reflection and refraction can be seen with naked eye. #optics #light
As time passed, the race to make a strong light source began. The light beam should be of single colour and coherent (analogous to two people walking in phase). Thus the race to make lasers began! #optics #lasers #photonics
But that was not it. There was a necessity to carry data over long distances and hence a new form of cable was invented - fiber optic cable. It then became faster and more efficient to transmit signals over fiber optic cables than copper wire. #fiberoptics #light #data
The field of fiber optics thus emerged - a way to guide light using fibers! Fiber optics finds application in a variety of fields such as sensing, medical diagnosis, apart from optical communication. #fiberoptics
With the dawn of #fiberoptics emerged yet another interesting field called #photonics. Photonics is about the generation, detection, and manipulation of #photons.
Optical fibers are capable of transmitting data over long distances and is the backbone of today's internet. Every smartphone manufacturing has something to do with Photonics. Lithography uses laser to etch out micro patterns, optics are used in display, etc.. #fiberoptics
So what is #nanophotonics? While so far, #photonics has been used in technology to create devices, the next leap is to see what will happen if light is allowed to interact with matter at the nanoscale level.
21st century saw the convulsion of of nanotechnology and photonics. Nanophotonics emerged and revolutionized the way we look at light. #nanophotonics #light
So what is a nanometer? You take a meter scale and split it a billion times and then look at just one unit. That's nanoscale! #nanophotonics
At this scale, light does not behave as it behaves at higher scales. The physical structure of the matter with which it starts interacting comes into picture. #nanophotonics
So how do we induce interactions between light and matter at nanoscale level. There are two ways to do it. One, confine light to dimensions that are smaller than the wavelength of light and two, confine matter to nano dimensions. #nanophotonics
Some prominent areas where nanophotonics has tremendous applications are spectroscopy, optical communication, solar cells, etc. We will look at them in more detail from tomorrow.
That's a brief story of how nanophotonics emerged. Do you have any question? #nanophotonics https://t.co/cM3zv2R5Ce
I will meet you all tomorrow with more nanostuff. Stay tuned! https://t.co/Lhu55suYbx
Hey all! Good evening! Today, let us talk about nanophotonics that is bioinspired. We will talk about photonic crystals, chemical linking, and biomaterials. #nanophotonics #bioinspired https://t.co/cG2ZHJqzMJ
Nanophotonic structures can be found everywhere in nature. Some examples include the wings of Morpho butterfly, moth eye, and beetle's cuticle. #nanophotonics #bioinspired
What is the reason for such nanophotonic structures to occur in nature? #nanophotonics #bioinspired https://t.co/tV2ofHayYz
In nature, we have both preys and predators. Some moths have evolutionarily developed an anti-reflective ability on the eyes, thanks to the presence of nanophotonic structures. This prevents visible light from being reflected off moths' eyes and thus helps moths to escape.
So what is there to be inspired from the moth eyes? #nanophotonics #biomimicry https://t.co/QsYHzUAVQl
Scientists are now designing novel procedures to construct a nano sphere monolayer using several deposition and plasma techniques. The biomimicked structure can now be applied to solar cells, monitors, and LEDs. #nanophotonics #biomimicry
Let me give some more examples. For improving light extraction from LEDs, directionally controlled fluorescence emission in butterflies has been an inspiration. #nanophotonics #biomimicry #butterflies https://t.co/F1DarR9iXA
Another example is that of a chameleon's skin which has a dynamically toned periodic two dimensional structure. #nanophotonics #biomimicry https://t.co/jX0UW7oIDV
Biomimicking certain natural nanophotonic structures has avoided overheating in hot climates. For example, desert ants have surfaces covered with nanostructures which reflect off light and hence they can search for food without feeling the heat. #nanophotonics #biomimicry https://t.co/QigizY0dXJ
But is it easy to develop these nanostructures in lab? #nanophotonics #biomimicry Not really and thus we again look into nature itself for solution.
The answer to the question is a process called biotemplating. With this technique, researchers exploit natural biological materials for creating replica of their highly ordered morphologies. #nanophotonics #biomimicry
Nature has also inspired the development of photonic components such as lasers and mirrors. The question we need to ask is why we need biocompatible and nanoscale photonic components? #nanophotonics #biomimicry
Optical technology is essential for rapid and efficient delivery of healthcare to patients. Hence there is a need to miniaturize devices that can be implanted in patients for continuous monitoring. #nanophotonics #healthcare #bioinspired
Optical components such as diffraction gratings, photonic crystals, plasmonic devices, and photodetectors have been designed based on the natural world. #nanophotonics #nature #opticalcomponents
#silk has been used to create a micro prism reflector array that acts as a diffraction grating. The grating had been used for imaging and sensing. #nanophotonics #bioinspired
Three dimensional photonic crystals have been fabricated with the help of silk. These shows iridescence when used inside biological tissue which can be used for refractive index measurement and for laser induced heating. #nanophotonics
A lot of biomaterials fluoresce and a few of them have quantum yield which makes them suitable for use as optical gain media which is of prime importance in creating lasers. #nanophotonics #nature #lasers
Biopolymers in thin film form can be used as cavity mirrors which are again important for creating nanoscale lasers that are biologically compatible. #nanophotonics #lasers
With the combination of such nanoscale gain media and cavity mirrors, one can efficiently create nanoscale lasers that can be implanted in patients for sensing and diagnostic purposes. #nanophotonics #lasers
With this we come to the end of today's session. Any doubts? Is there anything else you would like to know regarding bioinspiration in Photonics? Do ask. See you tomorrow! #nanophotonics #bioinspired https://t.co/HNmv8aZJfI
Good evening people! I hope you all are having a great day :) It is time to begin today's session. Today, we will talk about nanoscale quantum optics! #nanophotonics #quantumoptics #light https://t.co/A4cK2WWSUy
@sivashakthia [admin] "Dancing Light at Nanoscale" Extended conversation with @sivashakthia is out now - https://t.co/Ly4IPTyGSy
On monday, we talked about how photonic technologies are important for us. To better develop these systems at the nanoscale level, we need to understand the fundamental laws of quantum physics. Nanoscale quantum optics is all about that. #nanophotonics #quantumoptics #light
These sophisticated technologies are of use for our well being such as health care, security, and economic growth. Photonic devices have gained prominent importance over other technologies, thanks to the advantages they offer at the quantum level. #nanophotonics #quantumoptics.
Light based processes such as absorption, propagation, and even light storage can be exploited at the quantum level. But the interaction of single photons with matter at nanoscale level is very weak. #nanophotonics #quantumoptics #light
This dearth is obstacle for creating a rapport between quantum physics and photonic devices. Nanophotonics, as as field, addresses these issues by funneling down light to nanoscale dimensions. #nanophotonics #quantumoptics
On overcoming the challenges, we can see significant breakthroughs in the field of sensing, metrology, information processing at the quantum and classical level, etc. #nanophotonics #quantumoptics #light
Let us look at what the current scenario is like in this area of research. #nanophotonics #quantumoptics #lightmatter
The first focus has been on the creation of novel materials like graphene, silicon, and meta materials that can be used for probing light matter interaction at the nanoscale level. #nanophotonics #quantumoptics
The next focus is on devices that will be used for facilitating and controlling strong light matter interaction. Some examples of this include photonic integrated circuits, nanofibers, plasmonic structures, and superconductors. #nanophotonics #quantumoptics
Now that we know the possible materials and devices, the next aspect is to look into quantum degrees of freedom. For this, color centers in solids, ions, and neutral atoms have been used. For single photon sources, organic molecules, 2D materials are used.
This is an example of a fully integrated quantum circuit. #nanophotonics #quantumoptics Cred: Agio M. https://t.co/lwaMFdS9Vw
To funnel light to nanoscale dimensions, one uses metamaterial which unlike conventional material such as glass does not possess a positive index of refraction. #nanophotonics #quantumoptics
The origin of such a behaviour for metamaterials is due to rationally designed geometry, composition, and arrangement of nanostructured building blocks. #nanophotonics #quantumoptics
By using single photons for switching and routing through the exploitation of quantum mechanical phenomena, one can have efficient computing in the future. #nanophotonics #quantumoptics
When combined with tiny optical emitters, metamaterials could make possible a hybrid technology that uses quantum light in future computers. #nanophotonics #quantumoptics
Computers that operate on quantum optics would exploit qubits which exist in both the on and off state simultaneously. #nanophotonics #quantumoptics https://t.co/3g1AY7GzLF
The prowess of employing qubits is that it enhances the computer's power and memory, thereby increasing it's working capacity. #nanophotonics #QuantumComputing https://t.co/nGBNIyUCtY
That is just a brief introduction to quantum optics at the nanoscale level. If you would like to know more, do let me know! Until then, bye people! #nanophotonics #quantumoptics https://t.co/dfon8NjvTi
Hey tweeps! How is the day treating you so far? I had a long day and I will be winding it up with this Twitter session. Here is what we are going to look at. Are we facing a telecommunication crunch? #nanophotonics #optics #telecommunication #data
If you are reading tweet on your phone or your laptop, thank optical physicists. The world of internet is revolutionized by optical principles. #telecommunication #optics #data #internet
While browsing, your computer converts the human language into electrical signals. These electrical signals are then converted into optical signal through a certain optical process. The optical signal reaches the server to collect information and returns back to the computer.
The optical signals are light pulses generated using lasers and the medium which carry these signals back and forth are called fiber optic cables. #telecommunication #optics #data #internet #nanophotonics
The cables carry light through total internal reflection which is a process by which light gets guided inside the fiber. The fibers are referred to as single mode fiber since they have the capacity to support just one mode of the light. #fiberoptics
Though the information travels at the speed of light, encoding data onto light and processing them affects data speeds. #telecommunication #data #internet
Apart from that, we do not have the capacity to meet the growing demands for faster internet and more channels. We are already at the verge of using the visible light bandwidth. #telecommunication #fiberoptics #data #internet
So, there are two missing links to achieve ultrafast, broadband transmission. 1. To enhance the amount of data transferred and 2. To enhance the processing of signals at launch and output. #nanophotonics #telecommunication #internet
Let us look at the issues one by one. To enhance the amount of data that can be transferred, the way is to let the optical fibers carry more modes. So instead of encoding data just on light's spectrum, it is essential to look at other properties that can be exploited.
The oscillation or shape of light are other parameters that can be used to encode data. This way, we can make use of the several modes at the same time without any interference. #telecommunication #nanophotonics #data
The idea is to twist the light beam into a spiral to increase its capacity. This is referred to as light in a state of orbital angular momentum. #telecommunication #data
But how to improve the encoding process. For that, a nanophotonic chip designed by RMIT's laboratory comes into picture. #nanophotonics #data #internet
The miniature chip is designed to separate different orbital angular momentum states of light in a continuous order and to decode the information carried by twisted light. #nanophotonics #telecommunication #internet
Previously, this would call for instruments the size of a table which we know is not practical for telecommunication. So the researchers use topological nano sheets a fraction of a millimeter and they fit well on the end of an optical fiber. #nanophotonics #telecommunication
Another main advantage is that the material used in the device is compatible with silicon based materials used in the telecommunication industry. #telecommunication #nanophotonics
The technology is of high performance, low cost and tiny size and makes it a viable application for the next generation of broadband optical communications.
It is demonstrated that the processing speed has been increased by about 100 times which is quite exciting for the telecommunication sector. #telecommunication #nanophotonics
So yay! It is going to be all the more better soon! With this, I sign off for today. https://t.co/GoBOH3slzf
Hey people! Good morning :) Today we are beginning the session a bit earlier. With today's session, we will wind up discussion about nanophotonics. Tomorrow, we will discuss more about scicomm. You ready? #nanophotonics #scicomm
There are two things that I would like to do today. I will briefly tell you about the future challenges in nanophotonics. The tweets are mostly based out of a report by a panel of nano technologists. You can ask me any question in the field of optics and we will discuss that.
The tweet highlights ten different areas which are promising candidates for the future of technology. #nanophotonics #optics
1. Quantum optics, where nanophotonics can help build one-chip integrated optical circuitry for performing tasks in quantum information processing. #nanophotonics #quantumoptics
2. Telecommunications, where nanophotonic circuitry can help dramatically shrink the physical size and power consumption of devices such as modulators, switches, and lasers. #nanophotonics #telecommunications
3. Data storage, in which plasmonics can help take magnetic storage to new levels of data density through heat-assisted magnetic recording. #datastorage #nanophotonics
4. Medical therapies and Diagnostics, where the interaction between nanoparticles and light can be used for imaging purposes or to kill cancerous cells through localized heating or even light-induced drug delivery. #medicine #nanophotonics
5. Nanoscale imaging involving probes, optical antennas or super-lens techniques to image beyond the diffraction limit. #nanophotonics #imaging
6. Molecular scale sensors using nanophotonic technology to offer single-molecule detection and identification. #nanophotonics #sensing
7. Nanotagging, in which metamaterials and nanostructured barcodes can be used to combat counterfeiting. #nanophotonics #barcodes
8. LEDs and solar cells, where nano structuring can be used to optimize the emission and absorption of light. #nanophotonics #efficiency
9. New processing techniques for fabrication and lithography at higher resolutions. #nanophotonics
10. Nanophotonic materials with custom-designed optical properties. #nanophotonics #materials
I keep this thread open for all to post your questions about optics, photonics, and nanophotonics. Let us discuss :) https://t.co/pAwA5FsSH5
Good morning people! It is my last day over here. It was a great week and I had real fun curating the account. If you would like to discuss more about microwave/nano photonics, do say hi at @sivashakthia. Today, we will talk a bit about scicomm and wind up. #scicomm https://t.co/Exvffsim0O
Most of the #scicomm that I do involves teaching school kids about the importance of science. I feel that's the right age to instil curiosity.
I started taking part in service learning programs to better understand what it means to communicate the science that I am doing. #scicomm
Sometimes it is easier to do science than communicate and thus it requires good training. #scicomm
In fact, I would say science communication is the only way to know if you have understood your science well. #scicomm
I have been involved in #scicomm for the last 10 years or so. Like I started teaching school kids in schools that were devoid of enough facilities. Then in Ph.D, I started the Optical Society student chapter where the outreach programs were extended to colleges too.
While it was fun hosting various outreach programs, I have always felt something missing for which I have not really found an answer. #scicomm for the visually impaired. #visuallyimpaired
During various occasions, I got to talk to several visually impaired students. These students generally don't have access to science education since they cannot SEE. So my main goal in #scicomm which I haven't reached so far is to take science to the visually impaired.
Another common challenge is to convince the importance of #scicomm. Most of the time, the efforts of science communicators go unnoticed. In a university or college, professors don't appreciate the idea of their students taking part in science communication activities.
Oftentimes, I have felt confident about concepts that I have explained school students before writing a paper. This raises another important question. How well do we write our scientific and technical papers?
My personal opinion is that a scientific paper should read like a story instead of an agglomeration of random facts that are results of an experiment. Just ripping off content and putting them under titles such as 'introduction', 'results' doesn't make a paper appealing. #scicomm
This is something which is usually ignored as a result of which the difficulty arises to read a lit of scientific papers. #scicomm
The next point that I would like to talk about is the existence of 'pseudoscience'. The basic thing is that it needs a lot of bravery to talk against pseudoscience. #scicomm
Recently, I started The No Nonsense Science Club along with my friend. It is essentially a FB page where the motive is to bust common misconceptions and disseminate the information in a few Indian languages. #scicomm #pseudoscience
While it was a good start, I did have to face some trolls calling me names. But it is often a responsibility to cut the spread of pseudoscientific concepts as much as possible. #scicomm #pseudoscience
Do discuss what are some challenges you have faced while communicating science. #scicomm #challenges
What do you like better when it comes to science writing? Discuss.
@AlexGelle @sivashakthia As of now, I only teach by talking to them. As an optics student, I often find it difficult to talk about colors and so I use analogies instead. For people with special needs, it is important to have a one on one interaction because their perspective can differ a lot from ours.
Thanks for being a great audience! It was such a wonderful opportunity to have curated this account:) Keep in touch and let us talk everything about science @sivashakthia Bye, bye! #nanophotonics #optics #scicomm https://t.co/zqaX6pD6PD
[admin] Thank you Siva (@sivashaktia) for an insightful week of dancing light at nanoscale. More about Siva - https://t.co/Ly4IPTyGSy
Kameron Kilchrist
[admin] "Buidling New Medicines" Please welcome this week's curator - Kamron (@itskameronyall ) introductory podcast - https://t.co/nfABuZY7Mg
Hi everyone! Kameron here. It’s just after midnight local time here, and I’ll be your curator this week. Tomorrow, I’ll properly introduce myself, but for now, I’d love to hear about you! Who are you, dear readers, and what should do you want to talk about this week?
Are viruses nanoparticles?
Hey Twitter! Sorry I’m late to start this Monday party! I, @itskameronyall, will be curating @RealSci_Nano this week, so it’s only fair I introduce myself and tell you what I do. (A thread)
I grew up in the heart of Cajun country, in south Louisiana. I went to my local state flagship university, @LSU (#GEAUXTIGERS). Which, by the way, let me say—public schools are important. Call your state legislators and tell them how important your public unis are!
While I was at LSU, we faced several incredibly painful budget cuts that caused tuition to go up (RAPIDLY) and cut services on campus. I majored in biological engineering. Three major memories stick out to me, and some minor ones.
1, I was very active in my schools LGBTQ group, @SpectrumLSU. This was a major part of our social lives in the capital of a very conservative state. Do you part to create a supportive community for those around you!
2. It is hard to understate how jealous I was of schools with more resources (and we had decent resources!). I really wanted to major in biomedical engineering, but the major wasn’t offered. Luckily... 3. I was able to do undergrad research in a tissue engineering lab...
...where we studied nanocomposite materials and how they interacted with cells. I learned analytical techniques like scanning electron microscopy, which lets us look at extremely small things.
I also had the opportunity to do some cool undergraduate research in the chemistry department, where we studied how flame retardant particles were distributed in plastic, and how these particles moved and dissolved under heating.
THE TECHNIQUE TO DO THIS WAS NUTS!!! My prof built a μ-CT using the X Ray emissions of a synchrotron at the Louisiana Center for Advanced Microstructures and Devices. This is basically a giant ring in which electrons in a vacuum tube are accelerated to a significant fraction...
...of the speed of light. Giant electromagnets bend the electrons back into the ring. Every time the electrons get bent, they let out a stream of high energy photons called bremsstrahlung. We used these photons to take projection Xrays of our sample, then turn it a bit & repeat
This gave us projections which were then reconstructed into micron scale 3D reconstructions. This was my introduction to computational image analysis, a set of techniques I turn to time and time again.
Eventually, I applied to graduate schools all over the country. I knew I was interested in nano, biomedical engineering, tissue engineering, and drug delivery. I wanted to make an impact on human health.
With some fantastic mentorship from a prof in my dept, I wrote a successful @NSFGRFP application. Before getting the fellowship, I wasn’t sure I wanted to go to grad school.
In fact, this is a lesson I’d like to share with you: let life make some important decisions for you, and don’t fight it. If a pretty door opens, walk through it. (But think about what kind of doors you’re looking for, and keep an eye out)
So I visit some grad schools and after a couple visits I’m told I won this fellowship. Lucky for me, I had REALLY enjoyed my visit to @VandyBME and decided to join @Duvall_Lab_VU where I got to study nanoscale drug delivery. A dream come true!
Not only did I get to spend those years learning about self assembling polymers that form nanoscale drug delivery vehicles, but I got the opportunity to build a broad base of knowledge in several different areas.
I think that’s about enough ancient history, let’s talk about more recent stuff. My PhD research resulted in 3 research stories, and I’ll give you the short summary.
But first: some scientific background. A variety of molecules could be great medicines, but they’re not very effective because of specific cellular barriers that evolution has created. The one I have spent the most time thinking about is the endosomal membrane.
You can think of the endosome as a little cell stomach. It’s the digestive system for a cell. Our craziest drugs made of nucleic acid’s and proteins get destroyed here. The focus of my PhD lab was to get those drugs out of the endosome and into the cell where they can be active
A previous grad student had developed a nanoscale drug delivery system for peptides that worked really well. It was my job to figure out how it worked so well, and we did! We used pharmacologic techniques as well as SEM and TEM to figure out how our nanoparticles worked
Along the way, I was really frustrated by how hard this research was. We discovered a paper another lab had published showing a protein called Gal8 works to find damaged endosomes. When we watched fluorescent Gal8, it went straight to disrupted endosomes!
We still weren’t really satisfied with this system, so we thought about how to improve it. We then created a split Luciferase system wherein a luciferase enzyme becomes bioactive upon endosomal disruption. We can now measure endosomal disruption in even higher throughput!
We recently submitted this manuscript as a pre-print, the first ever from that group! You can read all about it over at @biorxivpreprint !
As I finished up my PhD (defended July 28! Woohoo!), I applied for industry jobs all over the country and eventually settled on an industry postdoc doing cutting edge research with protein therapeutics
with @JanssenUS here in La Jolla where I have the coooooolest project, exploring new applications of our tech. Hopefully I’ll be able to share this work when we have a paper in the next couple years!
So, dear readers, thanks for making it to the end of this thread. Did you know Twitter has a limit on thread length? We’re at it. Now that you know a bit about me, I’d love to hear more about you and what you want to talk about this week! Reply, retweet, and let’s have a blast!
[admin] "Building New Medicines" Listen to the podcast where we dive deeper with @itskameronyall https://t.co/nfABuZY7Mg
Let's talk about intracellular drug delivery, and why it's important! Also, viruses are nanoparticles. Fight me.
Biology is made of large molecules. DNA is used to make mRNA and mRNA is used to make proteins. Proteins fold up and do useful stuff. Cells use proteins to talk to each other. Sometimes, proteins misbehave, due to improper instructions from the DNA or the RNA.
We've come a long way in terms of understanding what genes can cause disease, but what if there were a way to turn off diseases by turning off the bad gene?
That's exactly what some types of intracellular-acting medicines do! Therapies like antisense oligonucleotides, small interfering RNAs, and even gene editing platforms like CRISPR, TALENS, and ZFNs can be used to reprogram cells from the inside out.
Unfortunately, those things are stuck on the outside of cells. And if they do enter cells, they're probably stuck in an endosome. My PhD research looked at the molecular mechanisms of these processes, to understand how we could engineer smarter nanoparticles...
to break down endosomal membranes to deliver drugs to the inside of cells. A few days ago, I asked whether you thought viruses were nanoparticles https://t.co/FrQaddOTSQ
Personally, I think viruses are definitely nanoparticles, and they're more efficient at getting foreign DNA into our cells that anything humans have invented! Viruses are the ultimate "smart" nanoparticle.
Viruses are used to reprogram cells for therapies, like CAR-T cells, which use synthetic lentivirus to reprogram T-cells to turn them into cancer killing machines. There are two CAR-T cell therapies on the market today! Amazing stuff!
There are also viruses being used to give patients a shot at a normal life, by giving them a gene they were born without. Truly, truly, crazy! There are two FDA approved viruses. One delivers RPE65 gene to the retinal pigmented epithelium, which literally cures blindness!!!!!
The other gives patients back SMN1 gene. Babes born with broken SMN1 will never sit up on their own. Most don't survive to their second birthday. In the clinical trial, 10 of the 21 patients could sit on their own for >30 seconds. AMAZING.
So, in my opinion, viruses are some of the oldest nanoparticles on earth!
Not sure if I’m allowed to post about non Nano stuff here but I just wanna share with y’all pictures of two of my orchids, Sharry and Roberta https://t.co/VXXGj37tcP
Hey Twitter! Ask me anything about grad school, finishing grad school, transitioning from academia to industry, or anything nano/medicine related!
It’s #followfriday — who are your favorite parts of SciTwitter to follow?
RT @MySci_PK: @Dinraal_ @RealSci_Nano @AmoebaSisters @realscientists @realsci_DE @fMRI_guy @upulie @iamscicomm @ProfRachelGaN @AJPrincep @B…
@MysterMyke @MySci_PK Great question! I think this is unlikely to be possible. It may be easier to turn chocolate into gunpowder though!
I've been thinking about this a lot lately, but I think that when peer reviewers request additional experiments "to improve impact" (rather than to support unsupported claims), authors should withdraw the manuscript and resubmit to higher impact journals.
The editor screens for interest and impact. The peer reviewers screen for solid science, sound methods, and well-supported claims. If my paper clearly says "XYZ in mice" and reviewers ask me for data in human cells/tissue, the scope of the paper has now changed.
Peer review is broken. Rather than focusing on whether claims are well-supported, reviewers often ask for new experiments to expand the impact/scope of the paper. Suggestions are welcome, but almost any critique of the manuscript should be addressable by either:
1. Doing a "killer" experiment that was not performed, i.e., was the central hypothesis directly tested or not? 2. Removing / weakening the claim. If the claim is central to the paper, see 1. All too often, authors say "We show ABC" and reviewers ask "but can you show DEF?"
This back and forth dance slows down science and cloisters results. My last published paper took ~13 months from first submission to the first journal to final acceptance in a second.
We had 7 peer reviewers at the second journal. Their comments certainly polished the manuscript and broadened its impact. But I don't believe the additional experiments substantially strengthened the central claim.
So, 13 months from 1st submission to acceptance. My most recent manuscript? It was about 13 months **from conception** to pre-print. Those results are there for the world to see and can stand on their own merits.
@Haris92 Unfortunately corrosion is not something I know anything at all about, sorry!
It’s important for scientists to take time off to recharge. How are you recharging this weekend?
Personally I’m tending to my garden and orchids, sipping iced coffee, and going to the gym later
https://t.co/aZ7nkdsG0V
Idk how to make basil thrive, but my mint, thyme, sage, oregano and strawberries are all doing great! https://t.co/hkMMZGAtvS
Also my very Southern California succulents 😂😅 https://t.co/gVkUYN7kqe
It’s been lovely curating @RealSci_Nano this week! You can always find me @itskameronyall, where I’m happy to chat about anything and everything!! (And my DMs are open) I’ll leave you with one of my favorite quotes, from Kurt Vonnegut:
Hello babies. Welcome to Earth. It’s hot in the summer and cold in the winter. It’s round and wet and crowded. On the outside, babies, you’ve got a hundred years here. There’s only one rule that I know of, babies—God damn it, you’ve got to be kind.” (God Bless You, Mr Rosewater)
[admin] Join us in thanking Kameron for an insightful week on Building New Medicines. More about @itskameronyall - https://t.co/nfABuZY7Mg
Laia Castilla i Amorós
[admin] "Cooking at Nanoscale with Colloidal Chemistry" Welcome this week's curator @laiacastilla Listen to what Laia will tweet about - https://t.co/RmROo1hg0i
Hi everyone! I'm Laia and I'll be your curator this week, tweeting from the beautiful Swiss Alps🏔 Sunday morning in here, taking a break from my work in colloidal chemistry. If you don't know what I'm talking about, no worries! You'll discover it this week;)
What do you do on the weekends to recharge your batteries?
@ScienceByDRE Right, apologies for leaving families with kids out of the poll 👶
I find having group meetings on Monday mornings very refreshing. As an experimentalist, I feel "physically" lazy to start my week working in the lab and it's nice to start doing something more mentally dynamic. When do you prefer to have your group meetings?
For the foreign to the colloidal chemistry field, colloidal nanoparticles consist of a, usually crystalline, inorganic core and a shell of ligands and surfactants which allow the nanoparticle to stay soluble in solution. https://t.co/PKeH1KSnHn
Colloidal nanoparticles are used for a huge variety of applications, including optoelectronics, catalysis and medicine among others. We can have purely metallic NPs, metaloxides and chalcogenides, perovskites or other types of quantum dots.. and even multinary combinations! https://t.co/J9nJycGI29
In this video, my colleague @nanochikki from @lnce_epfl explains, with a very nice analogy, how colloidal chemistry works. As when cooking, ilimited combinations give ilimited results and exploring them is always fun https://t.co/ys9x0vhGoU https://t.co/4anyJCbUeT
But as in cooking, we colloidal chemists also have a mortal enemy... REPRODUCIBILITY Do you have this problem in your fields too? Please tell me we are not alone 😭 https://t.co/r9RkeFLjX7
One of the advantages of colloidal chemistry versus other techniques is the synthetic control over size, shape and composition. From 2 nm to microscale, from spheres to star-like nanocrystals, from pure metals to multinary metal and metaloxides...
...colloidal chemistry is a platform to exploit the properties of known materials and to discover many more!
Thanks to the size control in colloidal chemistry we can study and use the quantum confinement effect observed in some nanocrystals like CdSe quantum dots https://t.co/1EMhXbSUQC
Because in this nanoscale range, their band gaps intrinsically depend on their size and light emission only occurs from the lowest confined level in the conduction "band" to the highest confined level in the valence "band" https://t.co/3Dx0oZTjVl
Plasmonic metals like Au also show interesting optical properties depending on their size and, as we will see later, also depending on their shape https://t.co/7TjwFHpN4u
@Felgraf_Physics Yeah I agree! But now I'm stuck synthesising grey things😢
RT @Rifat_Nano: Ever since the beginning of my PhD I have been synthesizing Au nanoparticles and here I am in my final year, and yet I am i…
@laiacastilla [admin] "Cooking at Nanoscale with Colloidal Chemistry" Delightful conversation with @laiacastilla on #34 podcast episode is out now - https://t.co/RmROo1hg0i
But not only can we tune the size of the nanocrystals, we can also make spheres, cubes, octahedra, tetrahedra, rods, plates, wires, stars, etc. All of them with different properties, different catalytic performance, different plasmonic effects...
@laiacastilla As mentioned in the podcast, one of the challenges I face every day is not knowing what exactly is going on during my syntheses. There are some beautiful papers that discuss this topic but usually in quite specific cases. What challenges do you face in your field?
Good morning everyone! Colloidal nanoparticles are useful tools in the understanding of materials performance. Because of their uniformity and tunability, they serve as a platform for structure-property relationship comprehension... (1)
... So, even though its general low capacity for scale-up for industrial applications, colloidal chemistry is a very promising technique for breakthrough discoveries in materials, medicine and energy (2)
I'd like to raise a question to the whole community about what's your approach in the way you do science. Do you do science for the sake of science and its beauty, or do you care more about the actual applications of it?
RT @KhristiLauren: Just because there’s an opening in your schedule doesn’t mean you’re free. Everything doesn’t need to be filled up and d…
@Felgraf_Physics Yeah that is actually a doubt I also have myself... is there anyone that can answer us here?
RT @Felgraf_Physics: @RealSci_Nano (Quick side question, as I haven't checked in a bit: Do we actually have a consensus yet as to *HOW* pla…
RT @professor_dave: Not a single woman's name appears in the GCSE science curriculum. #womeninSTEM https://t.co/hv21e2NeY2
When you work so much in the lab that you forget to drink water...
One of the drawbacks of colloidal chemistry is, that in most of the cases at least I'm familiar with, the resulting products strongly depend on the person carrying on the synthesis as well as the environment. Looking forward to a robotic lab assistant. https://t.co/V7yoREaLk7
RT @Felgraf_Physics: @RealSci_Nano YEP. I was about this || close to starting every AuNR synthesis (we wanted a specific plasmon-wavelength…
@Felgraf_Physics And then it’s a nightmare everytime I finish a batch of degassed solvent or precursor and I need to buy and/or degas somemore, praying so the reaction keeps working
Insitu studies are great but I’d rather do something like this (Fantastic voyage), chemistry version, than do night shifts in a synchrotron for a week https://t.co/uf9IgcaWJq
And the winner is... Science! But Applications was real close. My vote would have been for science too and that makes me think about how lucky we are for working in what we are passionate about https://t.co/5ZK17yGKdX
But it also makes me think about what is our responsability as scientists, especially in the world we live in today, with all its future challenges. Science per se is so beautiful... but should our duty with society come first?
[admin] Thank you Laia for a wonderful week about colloidal chemistry. Give her a follow @laiacastilla podcasts and more - https://t.co/RmROo1hg0i
Charlie Wand
[admin] "From Shampoo to LCD - a Theoretical Approach" Welcome @craywand for a week full of fun! listen to Charlie's science on the #35 podcast episode - https://t.co/6enyMqtpWP
I hope we could all learn something this week about colloidal chemistry, and than these words are no longer unknown for any of you
It’s been a pleasure curating @RealSci_Nano this week , I hope you found it as interesting and estimulating as I did:) You can always find me as @laiacastilla , I’ll be happy to talk with you guys there.
RT @realscientists: [admin] "From Shampoo to LCD - a Theoretical Approach" Welcome @craywand on @RealSci_Nano listen to Charlie's scienc…
Hi everyone! I’m Charlie, usually found at @craywand and I’m super excited to be curating @RealSci_Nano this week, thanks for having me! Here’s a bit of what I have planned. Today I’m going to talk about who I am, how I got here and what I do. 1/4
Monday I’m going to do an intro to soft matter: what do I mean when I say it. Tuesday I’ll talk about some of the approaches I use. Wednesday I’m going to talk about liquid crystals! They are one of my first love’s and I find them endlessly fascinating hopefully you will to. 2/4
Thursday I want to spark a conversation about what it’s like to work on such an interdisciplinary topic. Then Friday I’m going to talk about shampoo. 3/4
I don’t really have anything specific planned for Saturday, so we will see what crops up during the week! And that's it! I'm looking forward to lots of good discussions. 😀4/4
I grew up in Swindon a medium-sized town in Wiltshire. According to a recent study, students from Swindon are among the least likely in England to go to uni. Other things it’s famous for are the magic roundabout and trains. 1/9 https://t.co/qh33lTpWfe
I left Swindon at 18 and went down the road to Oxford University to study Chemistry in St Hilda’s College @hilda_beastoxf. When I started it was a women's college but went mixed when I was in my final year. 2/9
Whilst I was there I was introduced to computational/theoretical chemistry as part of my Master’s project. Through this and a summer internship at @ChemistryatYork I discovered it was something I was good at. 3/9
This all lead me to do my PhD at @ChemistryatYork looking at liquid crystals. My PhD was difficult – I didn’t really know what was expected of me or what to expect from the programme and I had a rough time of it. But I stuck it out and got some really nice results. 4/9 https://t.co/BAhmwWfWc8
From then I had a year out before moving to Sweden to work at the Swedish School of Textiles in Borås. Borås is a city of around 65k people in the West of Sweden, close to Gothenburg and originally known for it’s textiles. It also has a lot of street art, including Pinocchio. 5/9 https://t.co/85iuvPS95h
I worked jointly between the Textile school and the University of Borås, which was dual language between Swedish and English. It’s quite a small uni, with around 11k students (vs 24k at Oxford). It was able to confer Doctoral degrees in 2014, the year before I arrived. 6/9
From there I came back to the UK and spent time at @ChemCambridge before moving to @ChemEngManUni where I work in the multiscale modelling group and I’ve fallen in love with Manchester as a city. 7/9
Outside of work I’m active in the LGBTQ community and regularly go to @Biphoria. I have been out as bisexual since I was a teenager and transitioned during my PhD. Making STEM a supportive place to all people results in better science and happier people, big pluses all round. 8/9 https://t.co/wGpbuz0Vnz
So that’s me in a nutshell! If there’s anything you’d like to know more about, ask away! 9/9
Good afternoon everyone! I hope you are all having a less busy day than me! I have already had two meetings and a phone call this morning and it's only lunch time!
Today I’m going to attempt to answer the question “what is soft matter”? The term covers a huge variety of systems and I’m only going to touch on a few of my favourite ones. I guess the flippant answer is soft matter is condensed matter that is soft
What do I mean by soft? It’s not very obvious. E.g., if you have a plastic bottle of liquid soap, both the packaging and the soap fall under soft matter despite seeming to have very different material properties. So what do these 2 materials have in common to both be soft matter? https://t.co/bYwlPY5TBy
If we consider the two at the mesoscopic level, somewhere between the nanoscale (i.e. size of an atom) and micron size (i.e. visible under a microscope), they share a number of similarities. Both have physical structures on this level that determine the overall properties.
In both cases the mesostructure can be deformed with relatively little energy, on the scale with thermal energy at room temperature. This is why the soap is “liquid”, and the bottle can be produced at easily accessible temperatures.
These mesostructures can make it difficult to predict the physical properties from molecular composition alone – and (to me) this is what makes soft matter so interesting! The term “soft matter” can cover a huge range of materials, across all areas of our daily lives.
From make-up to tires, even mobile phone screens, all wouldn’t be possible without soft matter somewhere. With so much variation, this is a huge and vibrant field of research. Personally, I’ve been involved with work on liquid crystals, surfactants (like in the soap) and polymers https://t.co/g3C48u4dqy
Happy Tuesday everyone! In my opinion the worst day of the week. So to brighten it up today I’m going to talk a bit about the type of simulations I use to investigate soft matter. Simulations are basically virtual experiments that run “in silico”, i.e. on a computer. 1/13
As with “wet” science, there is a vast range of possible approaches, so I’m just going to talk about my little corner of them. I use virtual beads to represent atoms (or groups of atoms). Deciding how to model different interactions depends on what you are interested in. 2/13
Each bead you model costs computer processing power and it is currently not possible to model huge systems at an atomic level (i.e. one bead per atom). So you have to choose your model based on the length and time scale you are interested in. 3/13 https://t.co/qQFIDARdVg
If you want to look at the interaction between a few molecules, it is easy to represent each atom separately. That’s what I did in this paper looking at polymer actuation. https://t.co/kcTxClez2T 4/13
If you want to look at a much larger system, you might not care what all the individual atoms are doing and you might represent a group of atoms as a single bead. This means that instead of the atomic scale, you can look on a mesoscale. https://t.co/jm7XK2rFsy 5/13
On an even larger scale you might not be interested in what the single molecules are doing and you model a group of molecules as a single bead. This is what I did for my PhD, we looked at micron-sized liquid crystal bubbles. https://t.co/lODKIYZwek 6/13
Deciding the model is a very important part, you put rubbish in you get rubbish out. There are a huge number of papers purely on model (also called force field) development. 7/13 https://t.co/Gin5dryFae
One of the trickiest things to model is water! Given the ubiquitous nature of water, a wide number of models exist (and are still being developed). No one model captures it perfectly and you have to carefully chose given what physical property you are interested in. 8/13
With all this difficulty in selecting a model, why bother doing it at all? In the lab, we know what water is and the melting temperature of ice. There are loads of really good reasons! 1. I’d be out of a job if we did that! 9/13
2. It is very difficult to know what is going on at the mesoscale experimentally. In the lab there may be impurities, the conditions at a specific point might not be known exactly. It’s possible to control all these things precisely in simulations. 10/13
3. We can see how changing one specific attribute can affect the system -e.g. changing a methyl group to a t-butyl group. This is much easier to do in simulations than having to do a whole new synthesis. 11/13
4. It gives information that might be very difficult (or even impossible) to know experimentally, such as how much energy it takes to break a micelle or how the molecules align in a liquid crystal phase. 12/13
Phew! I’ve written more than I expected about how to use particles to model soft matter; I didn’t get on to how we use these models! I’ll try to do a thread about that later in the week. 😊 13/13
[admin] "From Shampoo to LCD - a Theoretical Approach" extended podcast with @craywand out now Listen here 🎧🎙️ https://t.co/6enyMqtpWP
Hi everyone! Today I’m going to talk about liquid crystals, seemingly an oxymoron. How can crystals be liquid? Well, liquid crystal is actually a term for any state of matter that flows like a liquid but has some form of long range order. 1/15
The term liquid crystal (LC) actually covers lots of different phases. Broadly LC’s fall into two types, lyotropic and thermotropic. Today I’m going to focus on thermotropic – these are materials whose phase depends on the temperature (and pressure). 2/15
One thing all LC molecules have in common is some form of anisotropy, shape being a common one. For example, rod-like or disc-like molecules often form LC phases. This phenomenon isn’t unique to the molecular scale, anisotropic colloids can form LC phases. 3/15
You can even see LC ordering on a much bigger scale, a pile of coins or tree trunks floating down the river. 4/15 https://t.co/NgjBEZd7ey
The most disordered phase is called the nematic phase where all the molecules (say) point in average in one direction but have no positional order. This long range order but low viscosity means that the nematic phase has a number of unique and interesting properties. 5/15
For example, it is birefringent meaning it a different refractive index depending on the orientation of the molecule. This can lead to beautiful images under cross polarisers 6/15. (check out https://t.co/4CohduyQcx for some cool photos).
The direction that the molecules tend to point in can be influenced by a number of things, including surface treatment and applying a voltage. When doped with a small amount of chiral material, it causes a helical twist; like stacking tables that start to twist as they stack. https://t.co/z6dQB9xR5C
Now this is where things start to get even. This twist can actually guide light! And this is the basis for a lot of LCD displays. I found this awesome gif but couldn’t find who made it – if you know please tell me! 8/15 https://t.co/kqnYBBhDCL
Here the LC is sandwiched between cross polarisers. Without a voltage there is a twist in the molecules and the light can pass through. When a voltage is applied, this causes the twist to disappear and the light can no longer pass through the second polariser, appearing dark.
During my PhD I investigated what would happen when you confine the nematic (and chiral nematic) phase in bubbles of various geometries, including shells and toroids (donut-shaped). By confining the LC, you can induce (and hopefully control) defects in the fluid. 10/15
With planar anchoring the molecules lay flat at the surface and it’s physically impossible to cover a sphere with rods, similarly to this spherical dog. These ‘partings’ or defects are regions of disorder that have different properties to the surrounding nematic phase. 11/15 https://t.co/JlFfSo0moK
For example, they show up as black under cross polarisers. But remember, they are not “physical” objects and are free to move. We found that you can control the position, type and number of defects by varying in the shell thickness and the chiral pitch length. 12/15 https://t.co/RnY7fvSPR6
One of the nicest findings from my PhD work was that I predicted a transition from 4 to 2 defects as the chiral pitch length decreased which was later confirmed from experiments. Predictions like this is one of the ultimate goals of doing simulations! 13/15
I’ve written a short intro into this paper here: https://t.co/mEPUoNyUnB that explains the findings and importance in plain English. 14/15
And I’m going to leave it there today. There is so much I haven’t touched on, I’ve only really talked about a small bit of the most disordered phase. I didn’t even get to put in my gif of a mood ring! (Also based on LCs!). 15/15 https://t.co/WGNwoR8x6R
Wow, I can’t believe it is Thursday already! Today I’m going to talk about something a bit different – the importance and difficulty of working in an intrinsically interdisciplinary area of science. 1/9
The work I do has given me a chance to work with people from a wide range of backgrounds and in a number of different departments. My degree is in chemistry, but I’m now in a chemical engineering department. 2/9
Those don’t sound that different, but I swiftly learnt that they are! I have no idea how to design a power plant, whilst a chemical engineer will struggle with some of the stuff I know. I’ve also worked in a textile school, working with textile designers (amongst others). 3/9
One of my favourite things about working with people from different scientific backgrounds is the number of different ways we all approach the same problem. When it works, it’s definitely better than the sum of its parts. 4/9
But this leads me onto one of the difficulties – we all have our own vocabulary to describe things. A trivial example is Helmholtz free energy; as a chemist I write it ‘A’, but a physicist might write it ‘F’. Not a problem in itself, until I think ‘F’ is force (for example). 5/9
I’ve learnt that communication is key, from both sides and it can work really well. It’s also important to keep expectations grounded – I have no idea* what is reasonable for an experimentalist to do or how long it will take (*= slight exaggeration). 6/9
One thing I’m currently struggling with, and would love to hear your thoughts/experiences on the matter is how easy it is to progress from a postdoc in an inherently interdisciplinary area. Where do I fit? 7/9
My background is Chemistry, but I’ve worked in Chem Eng, and been shortlisted for jobs in Physics depts. Does this count against me when looking for permanent jobs? Will Chem Eng departments frown on my lack of Chem Eng degree? 8/9
Will Chemistry depts wonder why I haven’t been working in one for 60%+ of my postdoc time? How have other people dealt with this situation? Or are you in it as well? I'd be really interested to hear from you. 9/9
@MySci_PK I wonder if this is quite common for materials/ chem eng because people don't usually study them at school?
Happy Friday everyone! We’ve finally made it to the end of the week. Today I want to talk today a bit about something I’m currently working on – surfactants. They are super useful in everyday life and are found in a lot of household products. 1/15
All surfactants have the same basic molecular structure with a long water-hating (hydrophobic) tail joined to a water-loving (hydrophilic) head group. 2/15
This duality of behaviour causes surfactants to self-assemble in water. These phases can have long range order, or no order. In fact, phases with long range order are an example of the (other type) of liquid crystal phases. 3/15
These systems are called lyotropic liquid crystals, and again covers a range of different phases but I don’t want to go into that today. If you want to learn more about them, there’s a good video here: https://t.co/3QGOgEvuJ2 4/15
My current work looks at isotropic surfactant systems, that’s systems with no long range order. I work as part of @cafe4dm. The systems I’m specifically interested in are shampoo! 5/15 https://t.co/NXCAA2E47i
One of the most common ingredients in shampoo is SLES (aka sodium laurylethoxysulfate) is one of the most important ingredients in shampoo and shower gel - pick up a bottle and it is very likely to be the second ingredient listed after water! 6/15
SLES has a charged head group, which means that the salt concentration of the liquid affects the self-assembly. We use computer simulations to investigate what the phases look like. In particular we are interested in how these affect the thickness (viscosity) of the fluid. 7/15
We recently published the phase diagram of SLES, you can read a “plain English” summary here https://t.co/ZTqJzVXOFu. Most of this work that I’m going to talk about was actually done by Maria Panoukidou, a PhD student in the group. 8/15
At low salt concentration, the surfactants assemble into spherical aggregates known as micelles, protecting the water-hating tails from the water whilst exposing the water-loving head groups to it. This complex fluid is a similar thickness to water. 9/15
As the salt concentration increases the interactions between the charged head groups decreases and they can pack closer together and the micelle starts to grow into rod-like micelles. 10/15
As the salt concentration continues to rise, the micelles continue to grow and form long, wormlike micelles. 11/15
These micelles can be up to microns in length and they can become entangled, increasing the thickness of the fluid. A good analogy of this is a plate of spaghetti, when you try to pull one strand out more come with it. 12/15 https://t.co/cFw5Sl99VS
In shampoo the surfactants form this type of wormlike micelles. The mean micelle length and breakage time are really important, but very difficult to measure experimentally. This is where computer simulations come in handy. 13/15
As you keep adding salt to the wormlike micelles, there comes a point where branches start to form. These branches allow the stress to be relaxed in more ways and the thickness of the fluid actually decreases again. 14/15
Again these branches are difficult to quantify experimentally which is why we use computer simulations. If you are interested in reading the full paper, you can find it here. https://t.co/jm7XK2rFsy 15/15
Today is my last day curating here and I have to say I’ve really enjoyed it and had a great time. I didn’t really have anything planned for today, but looking over my threads this week I realised I haven’t actually talked about how to do simulations yet. 1/10
Performing a simulation itself isn’t very difficult, there is loads of user-friendly free software available to do it. The difficult thing is picking the appropriate approach. Rubbish in = rubbish out 2/10
I perform particle-based simulations which means I use virtual beads to represent atoms (or groups of atoms). From these we tend to be interested in averages over a large number of snapshots, or configurations. 3/10
There are two main categories to generate these snapshots – molecular dynamics type or Monte Carlo type methods. Both have pros and cons and I’ll go through them quickly here. There are also more advanced methods that use a combination of the two but I won’t go into those. 4/10
Molecular Dynamics a.k.a. MD. It essentially solves Newton’s equations of motion to advance the system. You* split the simulation into small time steps and calculate the change in forces, velocities and position acting on each bead. (* the computer) 5/10
Pros of MD: + You can get dynamical information out, such as diffusion, viscosity + It is conceptually easier than Monte Carlo (MC) 6/10 https://t.co/uYXb7Noo6F
Cons of MD: - You have to calculate the forces and store them. It may be non-trivial for non-spherical particles. - It is easy to get stuck in a meta-stable state which we are not interested in 7/10 https://t.co/KSnHbeZrZQ
Monte Carlo a.k.a. MC. It takes a completely different approach. You make a move at random – it could be a particle translation/rotation and accepts it based on an underlying probability distribution based on the conditions of interest (temperature, pressure etc). 8/10
Pros of MC: + Quicker than MD, you don’t need to calculate forces for the particles and so you store less information + You can perform “unphysical moves” (e.g. particle insertion) so you are less likely to get stuck in a high energy state and you need shorter simulations 9/10 https://t.co/aAyHzUndcp
Cons of MC: - No kinetic/dynamic information (there is no concept of time in MC!) - Not as many programs readily available to use as for MD 10/10 https://t.co/V5JgIZPhuD
[admin] Thank you @craywand for a wonderful week of insightful science. podcasts and more - https://t.co/6enyMqtpWP
Izzy Jayasinghe
[admin] "Visualizing Life at Nanoscale" welcome @i_jayas for a week of nanoscience. Podcast and more - https://t.co/0zV0IxGZ2B
Hi Nano Tweeps 👋🏾! Izzy here - my turn in the hotseat talking abt how we, in the Life Sciences, watch the building 🧱s of life. We'll see some of the tiniest & coolest things we've ever shone light on, some of the latest tech & the problems that we face as Nano🧑🏻🔬👨🏾🔬👩🏼🔬 (0/n)
First thing’s first [long thread] – How do we see the building blocks of life? It’s (relatively) easy. #superresolution microscopy. It’s a family of fluorescence microscopy techniques which allow us to see structures in the scale of ~ 1-200 nanometres. (1/n)
“WHY”, you may ask. What we know is, this is the scale in which the tiniest processes of life are carried out. These range from single biomolecules (e.g. DNA, proteins) doing their own things, to tiny machines and compartments inside cells. (2/n) [GIF: Liam Neeson saying “Why”] https://t.co/njF7zXkkvv
You might say, why not use X-ray or EM, as we have for decades. I’d say, “Aye”. If you want to watch these molecules orchestrate life, you need catch them in their natural habitats. You need to give them individual spectral signatures. Goodbye #monochrome (3/n) [GIF: conductor] https://t.co/keeeh61XyH
Enter #fluorescence. The spectral signature we give each molecule is a fluorescent tag. There are literally 💯s of tags . They tell us where each molecule is *relative* to other molecules or structures. Modern Cell & Molecular Biology is built on this contextual info. (4/n)
A decent microscope & a set of fluorescent tags will only get you to a resolution of ~ 200 nm. WHY: we’re rubbish at making lenses which can capture the light in the finest of diffraction patterns coming from smaller structures, as described by Abbe (not Abba) (5/n) [GIF: Abba] https://t.co/BhOEi6zeX0
The answer to this was #superresolution. The most popular version was called localisation 🔬. And it basically involves making the fluorescent tags on *individual* markers switch ON-&-OFF. Much like the Eiffel tower here. More a bit later. (6/n) [GIF: Eiffel Tower lights] https://t.co/pwgbsSjYwY
@martinjones78 😂 I'm trying to work out how many Abba references/GIFs I can fit into this week's Tweets. Always easier when it's not my personal Twitter account.
RT @i_jayas: If you are a STEMM researcher relying on govt funding, *please* sign this letter asking for the inquiry to be re-opened to exa…
RT @ProfRachelGaN: Take a few minutes to read and sign this letter! We need to achieve more transparency in how research funding policies…
RT @AJPrincep: Last chance to lend your support to ensuring equity and inclusion in UK research funding! https://t.co/RzP0joRoNS
So, here’s how it usually works. We have a cell w. tags on a set of targets. We can either photo-activate (hit the tags with 💡 to chemically modify them) to make them visible, or we can deplete those available for fluorescence – this makes them 'blink' (7/n) [GIF: cat blinking] https://t.co/d6ISVenPiW
This ‘blinking’ of fluorescent molecules is rapid. They are captured by a fast, sensitive camera. Here’s a movie of a typical recording (8/n): [video: fluorescent molecule photoblinking] https://t.co/PUHDPbpQhc
By computationally-localising the centroid of each blink at sub-pixel accuracy, one frame at a time, you can build up a map which (like magic) reveal the finer features of the structure. See this fab animation by @HenriquesLab (9/n) https://t.co/W83OQkzrz4
As Prof Henriques points out, the principles of reconstructing a #superresolution image is not unique to the nanoscale. Even a mobile phone camera can, in principle, do this: (10/n) https://t.co/6teFvjOeFS
@HenriquesLab You are so welcome. This animation has been so useful for talks. I can now imaging - not a lot of better ways to enjoy image acquisition than pairing it with creme brûlée.
@KLeoPullin Ooh! Good questions! This one first: The secret to sub-pixel accuracy of localising the centroids is 🥁🥁🥁🥁 curve-fitting. We know that each blink is ~ a 2D Gaussian in shape (the microscope optics and the refr. index in the sample dictate this)...
@KLeoPullin For each 'blink', if we took a line profile across it, as you say, you would have a boxy profile (histogram with blue boxes). But because we know that the shape of the unpixelated event is Gaussian, we can fit an infinitely spooth 2D gaussian (red) using a statistical protocol... https://t.co/7gP3tjrgdj
@KLeoPullin which allows us to pin point the centroid (essentially at the true peak of the red curve) with far greater precision than what the pixel grid alone would allow. Like magic. https://t.co/iZAHcnu9oO
@KLeoPullin Actually, there is a limit to how accurate you can be with pinpointing the centroid. The amount of noise in the images (which create uncertainty in the curve-fitting) restrict the "precision of localisation" to a few nanometres. But that's far better than 10s or 100s of nm.
@martinjones78 @LaineBioImaging I heard that @LaineBioImaging was better at strings than keyboard.
@KLeoPullin Excellent-questions^2. So, localisation microscopy doesn't directly rely on wavelength because the images are not formed directly by the emitted light. For each molecule, we map its centroid (based on the curve-fitting to each 'blink')... https://t.co/RENUj7gosY
@KLeoPullin It is the reconstruction put together from *that map of fine centroids* which can have a resolution of single-digit nanometres. So it is essentially a pointillist image. [GIF: 3D points cloud] https://t.co/8clEd9sYyu
@KLeoPullin Ooh! YES! This is my ongoing debate with our local data managers. The primary data are the image series which contain the 'blink' events of the fluorescent tags. These are fairly big (~ 5 Gb). The really useful data are the coordinates of the centroids & the fit parameters.
@KLeoPullin Once you have the list of coordinates and the related parameters, you can reconstruct the image it lots of different ways. There are actually lots of different rendering algorithms which have different strengths and weaknesses.
@KLeoPullin The most common ways to display the data is to show, rather than just where the points (left) are, a smoothed (not explicitly smoothed) image which shows the local density of detected points (right). So, intensity, still would reflect density of the fluorescent tags. https://t.co/tU8LjSfMZY
@DrBrianPatton Only one Abba GIF so far. So, please send some more pop culture references (I will take them from any decade).
In the early 2000s, there were 4-5 laboratories independently working on this principle. Different ways of tagging molecules, switching &/or localising. In the end, 3 gentlemen won the Nobel Prize in Chemistry in 2014 for #superresolution. (11/n) [Image: Hell, Betzig & Moerner] https://t.co/DWgj4Ixp0V
If you’re looking for inspiring scientific stories, I highly recommend this lecture by Betzig & Hess. Spoiler: Betzig was out of Science when they did it. They set up a microscope in Hess’ living room to do some of the very first experiments. (12/n) https://t.co/05h0rCeJJT
So emerged, in the 2000s, a range of #superresolution 🔬s known by acronyms like PALM, STORM, SIM, STED etc (more on these variations tomorrow). They all produced unbelievably sharp & detailed images. Here’s one from @SoellerLab in ~ 2008 (13/n) [image: resolution improvement] https://t.co/8knr0y0b3L
I was a PGR working on ways to apply fluorescence microscopy methods to study how proteins cluster within muscle cells in the heart. The pictures above were of clusters of a giant protein called ryanodine receptor, which I continue to study even today. (14/n)
The ways they cluster in the cell, we think, are key to the heartbeat. Enough said, #superresolution gave us the best window to see how these clusters. Here’s a little teaser for tomorrow: with even more resolution, we’ve seen even more details in them. (15/n)
By ~ 2010, #superresolution 🔬s were routinely achieving 20-70 nm of optical res in cells, tissues & even whole animals. It's now its own sub-discipline & we all 💕 sharing "before & after" images- -showing the resolution improvement. (16/n) [GIF: happy before & grumpy after) https://t.co/tDv0MYBbqy
Want to see microtubules? Have a look at before & after #superresolution (17/n) https://t.co/B5dvNuxk7o
What about the actin skeleton of cells? Do #superresolution! (18/n) https://t.co/7ouhXWygyN
The "podosomes" the 'feet' of cells, #superresolution has that covered too. (19/n) https://t.co/wKxiyNPwPb
Our very favourite: protein clustering: #superresolution has drilled down to that too. (20/ n) [image: magnifying glass held over cell with protein clusters] https://t.co/H1RaEEwvXG
Thanks to those who engaged today. Tomorrow, I will talk about the recent explosion of new #superresolution 🔬s. Some of them can blow your mind (up)… literally. I leave you with these images acquired by @christlet & team. Feast your eyes!! (21/n) https://t.co/lTHXf0FwPR
@i_jayas @vdiazucl @CandiceMajewski @realscientists I just 'liked' my own reply. Time to call it a day. [GIF: Mutley chuckling] https://t.co/YmymPnsHIb
@SPIEevents @i_jayas Thank you so much! There's more of this today, so please tune in.
Morning everyone 😃 ! Izzy *again* here. So, carrying on with the theme of #superresolution, I want to talk about what happened after 2010, because it has been a helluva ride. (1/n) [GIF: spiral rollercoaster] https://t.co/CGix1UHFA1
2010-2020 has been a golden decade for #superresolution tech because one can never have enough resolution! By 2019, we were achieving angstrom-level of localization precision and resolutions of ~ 1 nm. (2/n)
The first thing was, methods like STORM and PALM became better. We started to better-understand & control the sample chemistry which made them more user-friendly. We also saw was the advent of newer & cleverer ways of getting #superresolution. (3/n) [GIF: teacher spills liq N2] https://t.co/zltFJid8WP
Most of the new methods came from 3 areas: (A) Improved/innovative hardware. These included new flavours of structured illumination microscopy - more acronyms like iSIM/mSIM (4/n) https://t.co/cuNoM2CZSb
For sheer resolution, these've been fantastic. MINFLUX is a method which scan and localise markers using a 🍩-shaped laser spot. These can give you images at ~ 1 nm in resolution. Watch this lecture by Stefan Hell on how it works (5/n) https://t.co/R12KY5Ax6S [GIF: dog with🍩] https://t.co/GCWsqJqShD
B) The 2nd is using contextual info to improve resolution, imaging speed &/or reduce artefacts. So, we’ve got some *new* acronyms like SRRF, SOFI, 3B, HAWK. One of the 🆒 things, I think, about them is that seeing single blinks is no-longer mandatory (6/n) https://t.co/FVN8MDyQnE
These are mostly algorithmic methods which use additional information about samples to estimate the likely structure in #superresolution without having to see the full complement of the fluorescent tags as blinks. Result = faster & more versatile imaging (7/n) [GIF: roadrunner] https://t.co/vMCxtMKHMo
C) The final area of #superresolution 🔬 innovation is the chemistry of the fluorescent tags and the physical properties of the sample. This is the topic of Tweeting for the rest of today. (8/n) [GIF: dog with 🔬 & conical flask] https://t.co/T9weKuSHfI
@DrBrianPatton It's absolutely #fakenews to call it a lecturers' strike. Support and technical staff in universities are among the worst-treated colleagues. Their roles are casualised and often stifled by the lack of career advancement. I will be striking for the lecturers AND other staff.
Really interesting point (segue from the main thread) that 🔬, for many of us is a life passion. Projects and tech come and go but images one acquires are permanently etched into our memories. Am I right? https://t.co/AGDa7kZubI
OK, lunch-time Tuesday (is it Friday yet)? Here's me loading up on my ☕️ and on with some more #superresolution Tweets. (9/n) https://t.co/IRXtvQXLen
A big 💩 in 📍pointing the fluorescent tags accurately, is noise. In light 🔬, noise depends on a lot of things – the 📷 you use, how fast you record images (i.e. how quick the ‘blinks’ are) & how many photons you collect from each tag. (10/n) [GIF: noise on CRT TV] https://t.co/yseGzg0979
Classic #superresolution like dSTORM were notorious for limited control of noise. What you need, are noise-free images where the ‘blinks’ are easier to detect. Introducing: DNA-PAINT (🧬🎨). (11/n) [image: dSTORM & DNA-PAINT blinks] https://t.co/3LNVsaPHPh
🧬🎨: We separate the fluorescent tag from the 🎯. The tag is now linked to a short diffusible single-strand 🧬. The matching 🧬-strand marks the 🎯. It is lit by a thin sheet of light. You see the tag *only* when the tag has ‘docked’ with the target (12/n) [Image: DNA-PAINT] https://t.co/bq18Se3ZHo
You see them as lots of blinks because these dockings of the 🧬+tag are short-lived (~ 1 s). They actually looks like lots of blinks. They are not blinks #fakeblinks. But for us microscopists, these ‘blinks’ can be used the same way as blinks (13/n) [GIF: lots of eyes blinking] https://t.co/qvetG4BUwA
So, here’s the difference 🧬🎨 makes to the images. ‘Optical’ resolution of ~ 10 nm. (14/n) [Image: comparison of TIRF, dSTORM & 🧬🎨 images of a protein cluster] https://t.co/Ll7AVk1eZH
Fun fact: because tags are made of 🧬 & not attached physically to the 🎯s, you can use lots of unique pieces of 🧬s to image lots of diff 🎯s. You simply wash-in ➡️📸➡️ wash-out each tag to map multiple 🎯s on the same cell. (15/n) [image: 4 diff structures on same cell] https://t.co/Njmdzkwt2r
If you want to read more about it 👆🏾 (or see more pictures), See the paper by Jungmann et al (16/n) https://t.co/WPiHVloO5c
Right. I am hitting ⏸️on this thread for now. A bit of GIF burn-out and some long threads mean that I am now pulling over for a comfort break. Join me tomorrow for an introduction to an unlikely #superresolution technique which is now becoming mainstream. Night 💤! https://t.co/vrp3v0R5eN
Hi 👋🏾, I’m back again on this thread. The main reason that I said that 2010-2019 was the golden decade for #superresolution was because there were so many different chemistries & clever instrumentation which could also be combined (17/n). [GIF: powers combined] https://t.co/0TvwMEYo5m
One example is this method combining clever multi-angle imaging with imaging fluorescent tag blinking. They can see structures that are *inside* little membrane compartments which are *inside* cells. https://t.co/YZGkDsTLRS (18/n) [image: proteins inside mitochondria] https://t.co/4fdZbRf8Hm
Here’s another example of what is possible by combining two new types of instruments. This is #superresolution applied to a living immune cell going about its job inside the inner ear of a fish . (19/n) https://t.co/C9HNwWvh4d
But not all the innovations are about combining new kit or chemistry. @eboyden3 and colleagues shook up #superresolution when they said <paraphrasing>, “if you can’t see the small stuff, why not make the small thing bigger” (20/n) [GIF: Trump playing with Hoberman sphere] https://t.co/pRmUiCElWr
Enter stage-left, Expansion Microscopy. The idea was to take a 3D, imprint of the fluorescent tags & then inflate it. You are essentially blowing the finest of structures up into the spatial scale that's resolvable with existing 🔬s (21/n) [GIF: inflatable minion crushing 🚗] https://t.co/CGXqwYYRa9
Q: How do you take an imprint of a sample and/or inflate it? A: You use a hydrogel. There've been different recipes for this over the last 5-6 years – virtually all based on acrylamides. So if you have an imprint of a cell within it, all you need to do is add water (22/n)
Q: How much can you inflate a gel? A: A lot. Here’s a demonstration with 2 x gels which were formed in a 1.5 mL tube, one has been hydrated. Image credit: @TMDSheard If you design the ⚗️🧪right, it can inflate over 1000-fold in volume (23/n). [Image: expanded gel] https://t.co/Fj5Ncytqll
I am continuing my GIF game on a new angle of #superresolution today. Have a look at the thread which now looks at inflating cells. https://t.co/K6ifKAoTbS
[admin] "Visualizing Life at Nanoscale" extended conversation with the amazing Izzy (@i_jayas ) is out now - https://t.co/0zV0IxGZ2B
@TMDSheard So here’s what has been resolved with Expansion 🔬. Microtubules – some of the finest scaffolding filaments in cells. They also form these radiating patterns which facilitate the division of cells. These were now so crisp – using standard 🔬s (24/n) https://t.co/TASvQ1zxKZ
Expansion 🔬 wasn’t limited to cells. They could expand whole organs. This is an image volume of a whole brain. In #superresolution! Complete with every small structural detail of every nerve fibre 🤯. (25/n) https://t.co/H3TiGYzrQ5 [image: expanded mouse brain] https://t.co/K43syxOcJg
Of course, this chemical method is more powerful when you combine it with other #superresolution 🔬 s. For example, combining Expansion 🔬 with STED 🔬 gives you a level of detail which is just phenomenal (26/n) https://t.co/Ngs8DWaEM0
So, as optical 🔬ists chasing #superresolution, we really are spoiled for options. We can just line up the images acquired with different modalities, compare & pick the best ones that fit any experiment. (27/n) [image: protein lattices compared by modality. Credit: @TMDSheard] https://t.co/jP4b1qbT4U
Going into the future, because it is so unconventional, Expansion 🔬 needs to establish some standards. Questions like how isotropic &/or consistent the gel expansion is need better addressing. We will iron those out – soon enough (28/n) [GIF: we are in the endgame now] https://t.co/HW1xMsvhNH
Right-o. I am going to call it a day on the #superresolution thread. Please see 👇🏾 today's Tweets on Expansion 🔬in case you missed 📻 silence from me Thu & Fri as my colleagues & I will be at the @UCU strike. I will however answer 🔬 Qs on the thread https://t.co/TxMtd5YsDi
@ProfRachelGaN It's really impressive (and looks like a lot of work). This group managed to get more detail of the same structures, but in 2D images. https://t.co/0oogaJn4UN
@ProfRachelGaN You can find the preprint here. Looks like they used a bespoke 4-Pi system (there are commercial ones). For tomography, I suspect the lattice light-sheets would perform similarly well. The movie 👆🏾 from the fish inner 👂🏾is from one of those. https://t.co/uk15t4LJhB
@LaineBioImaging This looks like a Zen 🤔
@ProfRachelGaN My non-expert expl: The 3D image is built up from single marker blinks, localised in 3D, rather than 2D. The focal vol is still relatively thick (sub-micron), so blinks can occur anywhere within it. What 4Pi gives you is *very* good confidence in localising the blinks axially.
@ProfRachelGaN So, when you map the 3D coordinates of all the blinks coming from the imaging volume, what you get is a well-resolved 3D volume that is sub-micron in height. To sample a greater depth, one moves the focus axial and sample blinks from different depths. Hope I am making sense.
@ProfRachelGaN I suspect the total thickness of a sample one can practically image this way however is limited (to a few microns at best, I estimate). The lattice light sheet would have much better working depth.
@seis_matters Hot bath + 🍷can cure post-talk ailments. https://t.co/ZBtm6mTsk4
Hi 👋🏾, Just popping into Twitter briefly today before I hand over the 🔑s to @RealSci_Nano. I suspended my #AcademicTwitter presence whilst on #UCUstrikes to protect pensions, fair pay & workplace conditions. Back again for a few final words on navigating Science as an ECR [1/n]
As an early-career Nano 👩🏾🔬, I've had a privilege of working along some amazing 👩🏾🔬👨🏼🔬🧑🏻🔬👩🏿🔬s and to meet my heroes/heroines. But key to doing good nano science is career advancement/survival. Jumping between contracts is often ropey and stressful [2/n] [GIF: running on footbridge] https://t.co/c0JJmIeE0C
For me, being able to sustain my research on #superresolution has only been possible with job security, research funding, safety (both physical and emotional safety) in the workplace & the right mentorship. Hardships on these fronts are *not* a right-of-passage [3/n]
So, before I go, I want to do a bit of myth-busting about advancing a career in #Nano [4/n] [GIF: Jamie Hyneman in armoured suit & goggles saying, "when in doubt... C4"] https://t.co/cbjPKDhFJ4
Truth #1: When you get beyond the typical weekly working hrs, the extra time you spend in the lab has *no* relationship with either the quality of your #Nano research. It is no sign of a rare genius or a productive 👨🔬 as some may have you believe. [5/n] https://t.co/0GQNOtdGbN
Truth #2: It's never too early to apply for that extra funding. #Nano, esp #superresolution, is tough to do on the cheap. When I became a PI 4.5 yrs ago, I realised that I my grant-writing was my Achilles heel. Start early & keep at it. [6/n] [GIF: Horrified to find 👛 empty] https://t.co/pSo41bYQxL
Truth #3: If you're either a woman or from a minority working in #nano, you're there on merit! The limited data we have show that, if anything, women, people of colour or with disability are disadvantaged in funding allocation (& jobs & promotions) [7/n]. https://t.co/Ea9sPXME17
Contd... So, it is worthwhile getting involved in Equality, Diversity, Inclusion & Accessibility (EDI&A) discussions in your College, Uni, Institute or Company to set this right. DO NOT let anyone tell you that you are not there on merit, because chances are they are not [8/n]
Truth #4: Surrounding yourself with people who will tell the truth absolutely is better for your career & the science you do. I thrive today because of the honesty of my mentors, collaborators, reviewers & colleagues. Read my recent experiences 👇🏾. [9/n] https://t.co/BhE2YmSHbp
Truth #5: Respect is a two-way 🛣️; Giving basic consideration to colleagues & students, e.g. on non-work commitments, respecting their identities, addressing by their chosen pronouns & name, don't cost you anything. It will earn you their respect [10/n] [GIF: R.E.S.P.E.C.T] https://t.co/fKhXTJdCnS
Truth #6: Imposter Syndrome is real. Many in #nano, including me, suffer from it. *Do not feed the imposters* i.e. don't listen to that manager who says you're not ready to become a PI or to go for that promotion despite meeting all the criteria [11/n] [GIF: 🦆s complaining] https://t.co/fI7R415bHE
Truth #7: You don't always need the latest bit of 🔬 kit to do some cool #nano science (or #superresolution). You just need to differentiate your must-haves from the 🔔s & whistles. If you have 💷💷💵, spend it on collaboration & travel instead [12/n] [GIF: Abba: 💷,💷,💵] https://t.co/Lpry3KxtJy
Truth #8: Postgraduate researchers (PGRs) are the primary contributors of #nano in academia. For me, *all* of my recent contributions have come from working closely with talented and dedicated PGRs. They are professionals, & to me, they are colleagues [13/n] [GIF: #squad] https://t.co/O4rA904OSz
Contd... It's really time that we changed the culture that PGRs are "just students". There is a culture of exploitation and 'ownership' of PGRs in Science. This must stop. They are not the children of their supervisor, and should not be defined by the supervisor's name [14/n]
Truth #9. #manels or harassment have no place in #nano. There are so many women & gender-diverse innovators in #nano. If you see these in meetings/ workplaces, act immediately. Complain. Tell them to adopt a #codeofconduct. See this thread 👇🏾 [15/n] https://t.co/xc4AkN3HOS
"Code of conduct? What is that", you say, I hear. Here's a good example for conferences. There are also great examples on Twitter of codes of conduct for research groups and consortia. These are key to making a research space/meeting safe for all [16/n] https://t.co/WAUsH0QwJl
Truth #10. Everyone in #nano is human. So, be kind. [17/17] [GIF: Be-kind smiley face] https://t.co/zca3cMWMnf
Thank you to all of you who engaged. Any further questions/comments, please send them my way (@i_jayas). Over & out✌️🏾 [GIF: mic drop] https://t.co/hladvm2UdS https://t.co/bIAwOJJF8h
[admin] Thank you Izzy (@i_jayas ) for a wonderful week with the deep dive into visualizing life at the nanoscale. know more about Izzy and listen to the podcasts here - https://t.co/0zV0IxGZ2B
Amy Gelmi
[admin] "Frankenstein on the Nanoscale" Welcome this week's curator Amy (@DrTinyTaps ) Podcast and more - https://t.co/isbMODA9eT
Good morning tweeps! It's Monday morning down under, and the week is kicking off ☕️ Today I'll be introducing my research (what does Frankenstein have to do with nano??), scheduling around stem cells (more demanding than a toddler), and stanning AFM as my favourite nano-tool! https://t.co/fl750ShW90
"Frankenstein on the Nanoscale": - crazed scientist - body parts - teeny tiny lightning strikes Reality: - me - stem cells - teeny tiny electrode shocks So... basically the same. (1/n) https://t.co/Km6xbQCOlD
Alright, so perhaps my research isn't quite that dramatic 👩🔬 In a nutshell, I'm working to understand how stem cell fate can be triggered by electrical stimulation. It's a very interesting field within the broad area of tissue engineering. (2/n)
Understanding how stem cells respond to electrical stimulation (and there are many types of stimulation signals we can use) is tricky, with many mechanisms proposed and possibly participating. 🧐 (3/n)
I, not being a biologist through any stretch of the imagination, have taken a different approach in trying to figure out what is happening at the cellular level when we give the stem cells Frankenstein-ian therapy...🧫 (4/n)
Cue... atomic force microscopy!🔬Stay tuned on how an instrument developed for atomic level materials characterisation is a secret tool in the world of live single cell characterisation! https://t.co/gyPF1q70La
Atomic Force Microscopy - what's this nanoscale tool doing being bandied in the world of biology? Actually, hold up... what IS AFM? (1/6) https://t.co/OdIplyacdq
AFM is a type of scanning probe microscopy - a technique which won Gerd Binning and Heinrich Rohrer the 1986 Nobel Prize for Physics. In its simplest form, a physical probe is scanned across a surface and a laser is used to measure deflections of the probe. (2/6) https://t.co/1Krk18WcBd
As AFM involves 'feeling' the surface to produce an image or information, we aren't limited by the optical diffraction limit and can measure down to the picoscale (depending on your experimental set-up, of course!). (3/6)
Additionally, the only sample preparation required is that your sample is adhered to some degree to a substrate - no loose particles or floaties allowed! (4/6) https://t.co/zEHdlH0jC1
Finally, as this is a physical measurement, we aren't shackled by the need to dry, fix, stain, or resin mount samples. And we can perform these measurements in situ, in ambient or controlled environments. Which leads us to... (5/6)
The ideal technique to study single living cells! ☑️ Adherent cells grow happily on a substrate ☑️ In situ measurements- living cells in media and heated to the perfect 37C ☑️ No fixing or staining required to probe the cells (6/6)
This morning I had grand plans to seed my stem cells for upcoming experiments... Foiled! But I can take you on a fast paced tour from RMIT to @BioFab3D! https://t.co/IcHDCZetnY
Let's talk bio-AFM in more detail - specifically, some of the very cool new applications😎While bio-AFM can produce those traditional 3D AFM scans of living cells, the really powerful measurements can do so much more! Let's dive in ... (1/6) https://t.co/5LTymxBUxO
One of the more recent image modes which I love to use is called "Peak Force Mapping" (or Quantitative Imaging, or PeakForce Tapping/QNM depending on your AFM brand). This mode produces high resolution imaging with simultaneous nanoscale property mapping 😍 (2/6)
Why do I love this technique so much? It's gentle on the cells, and the level of information you gain is staggering! You can map membrane topography, underlying cytoskeletal topography, Young's modulus, and adhesion... every pixel carries a wealth of information! (3/6) https://t.co/1924gPr6ni
Here's a little something I prepared earlier... live cells on a glass substrate, imaged using our JPK Nanowizard 4. (4/6) https://t.co/BKxTUMs0ey
Imaging cells "because I want to" doesn't exactly help me write grants or papers - so what do I use it for? To study changes in the cells in real time - cytoskeletal or membrane topography is a tricky thing to measure in my stem cells, but now I have the perfect tool! (5/6)
Through using custom built devices (more on this later!) for our AFM, I apply a triggered stimulation to the cells to produce before/after comparisons, to understand how the cells are responding. This combination of biology, AFM, and engineering opens a whole new world! (6/6) https://t.co/ajSOTER3no
Collecting pins on my work lanyard is one of my quiet little joys 🤗 PS the lanyard is also special! #pinsforwins https://t.co/YA41UNJonL
@DrG_AFM Those ones are cool! Blood donation?
@DrG_AFM That's brilliant - I'm not allowed to donate blood in Australia as I was in the UK in 1989, and thus may harbour mad cow disease 🐮 So I made a point to donate blood during my postdoc in London!
It's the midweek bump and I'll carry my little bit of the universe with me today 🚀 #planetsinpockets https://t.co/dM61toopqy
Loving the #RSCPoster event, particularly the #RSCnano ! Keep that excellent science and sharing coming, and amplify the posters you want everyone to read! https://t.co/kFx88VTjTV
[admin] "Frankenstein on the Nanoscale" Longer conversation with Amy (@DrTinyTaps) on the 40th podcast episode is out now https://t.co/isbMODA9eT
Some of my more recent non fiction science reads that I've really enjoyed (and one 'food' based one). I'm always looking for recommendations! #stembookclub https://t.co/5OQt5qLHZW
One thing I love about my research is being multidisciplinary - but it's not for everyone. I'll throw it to the tweeps to see how you'd class your research: multidisciplinary, specialised, or collaborative with other fields?
@danieljmorse @MySci_PK I'd agree, I also enjoyed my multidisciplinary PhD! And postdocs are the perfect opportunity to focus in on a specific field, building on a broad foundation. Plus it gives you some scope to figure out what you are interested to do a postdoc, rather than feeling boxed in.
Interesting poll results so far- I'll add while I prefer being multidisciplinary, it certainly doesn't help the feeling of #impostersyndrome and makes it difficult to fit into more rigid discipline descriptors. Am I a chemist? Biologist? Engineer? I would say none but also all!
Our chemical store is running a fun game... And I have no idea any of these specific glassware! Any ideas? #badchemist https://t.co/OEWR7A5gBM
@anna_ceguerra Oh true! That was my first attempt at a twitter poll, I'll have to see if I can make it accept more than one option next time 😬
@jjmcv Oh wow, it really does look just like Thing, can't unsee it 😂 https://t.co/gWjXEhUCoM
@kizzythechemist Ha brilliant! Virtual lolly for you🍬😅
Today the stem cells were ready, and 3 types of media created this fleshy rainbow 🌈 These babies are contributing to my newest "discipline offshoot" research project. .. Bioinformatics! #benchtobyte https://t.co/jzQ1ZF468k
Multidisciplinary is the popular choice- a sign of the modern science? My research is starting to incorporate bioinformatics and machine learning, new to me but very relevant. What areas would you use to enhance your research? Which would you suggest for budding nano scientists?
Happy Friday! Turning away from research this morning, I'd like to talk about a topic I'm passionate about: retention of women in STEM. The 'leaky pipeline'. The graph below is from 2014, but the 'scissor' shape is all too familiar. (1/5) https://t.co/c59HsUQAWX
How do we address this? There are many approaches; from personal experience I see how tough it is to stay in STEM while balancing a new family. I was fortunate my partner could be a stay at home parent for our nugget's 3-9 months while I started my group leader position. (2/5)
I believe normalising equal parental leave will help this 'leaky pipe' - if both parents can take supported leave, we can reduce the expectation/pressure for women to press pause on their academic careers. Helping those who take leave maintain career momentum is vital too. (3/5)
This is something I'm working to address in policy, through getting involved with our Athena Swan program as well as through my position on the Academic Board at my university. (4/5)
Is this something you've experienced? Or have insight on? How do you try to instigate policy changes in your institutions? Does your institute make efforts to help in this? (5/5) https://t.co/joaGKj1yh2
@Felgraf_Physics Yeah that's definitely true, and I've worked with a lot of chemist who now make NP for cool bio sensing applications. In another life that could have been me... Turned down a PhD with quantum dots to go into bionic materials 🤔🤔
@Felgraf_Physics Also a second thought, I thought chemistry not always working was frustrating... Until I started live cell experiments. Those buggers are so unpredictable, and totally explains why biologists are so superstitious 🧫
Another awesome AFM application (from my PhD supervisor)- why use boring conventional probes when you can use an entire living cell instead? https://t.co/zUcL4AwHHT
It's a technique I love to use to quantify interactions between biomaterials and cells, and there aren't any other techniques really comparable in terms of molecular level information and time scale!
Plus when you affix a cell to the end of the probe it's like playing a high stakes nano game of 'claw'... https://t.co/Ln923oF7NZ
Seeing as it's Saturday night, time to kick back and listen to one of my favourite science related podcasts - @tpwky This Podcast Will Kill You is brilliant, and they've done a recent episode on coronaviruses! Super knowledgeable and pleasant hosts! #givemeaquarantini https://t.co/Kbm4x57k8o
[admin] Thank you Amy (@DrTinyTaps) for a wonderful week of nano science and an insight into the world of AFM Know more about Amy and listen to the podcasts here - https://t.co/isbMODA9eT
Dr Tanvir Hussain
[admin] “Surfaces made magical with Nanoparticles” Welcome this week's curator Tanvir (@tanvir_h) For Podcast and more - https://t.co/57XLvmNHx7
#NewProfilePic https://t.co/IB6wBXF0sz
👋 all, welcome to the week of “magical surface”. I will make a proper start tomorrow. In the meantime, I am posting my first ever publicly posted image from my research in 2006. Any guess? I was pleased to see the image is still in Wikipedia—my only wiki article contribution. https://t.co/49xyikVeLB
RT @ProfRachelGaN: Oooh! Lovely! One of my fave materials scientists, @tanvir_h, is running @RealSci_Nano this week. Looking forward to lea…
This was a commercially pure titanium particle (5-25 micrometers in diameter) hitting a 300 series stainless steel substrate at a velocity above 600 m/s. There was no heat involved. /2
This as my first ever experiment to make a commercially pure titanium coating. In a cold spray setup we have a powder feeder and a high pressure gas (in my case helium). We push the helium through a convergent divergent nozzle, also called a de-label nozzle like a rocket nozzle/3 https://t.co/MWMl0wKbA1
Helium going through the nozzle accelerates the powder particles to supersonic velocities. The powder we use are small. My hair is around 100 micrometer. The powder we use are in the range of 5-20 micrometer. /4
When the cold titanium hits the steel it deforms very quickly (strain rate of 10^9 per second of you really need to know). At that sort of conditions metal start behaving very differently. There is something called thermal softening. /5
This very soft metal start flowing and forms a jet. This jet (see the edge of the particle) removes any oxide from the metal surface and two metals come together and weld—it’s like magic. Cold welding. This bonding is super strong, more than 100 MPa. /6
How much is 100 MPa? You can hang my weight from a small disc and it won’t fail. This was my intro to surface engineering—a cold spray process. Those materials scientists out there would enjoy this seminal paper by Prof Assadi at Brunel https://t.co/U1l0uhFyDH /7
👆🏼was my first journal paper that I read on cold spray in 2006. It was tough but I fell in love with materials after reading that. What is happening here is similar to hitting a wall with a flour dough and the dough sticking to the wall for a couple of sec. /8
Now imagine being able to engineer the dough so it will not fall off. It will stick to the wall for ever! That is what I started my career on in 2006. /9
@AaronSlepkov Close. Thanks for engaging. Titanium into steel. But there was no melting involved. The particle was travelling around 600 m/s when it hit the steel.
RT @tigerinstemm: There are so many amazing women out there, in and out of STEM. There are still significant issues in recruiting girls and…
I am continuing the theme of cold gas spraying. 10+ years ago there was a big controversy. We all thought the bond strength of the coatings only come from metallurgical bond. My first ever journal paper introduced a concept called mechanical bonding. https://t.co/2dmF28XTl2 /1 https://t.co/q9xF4l5ujM https://t.co/6zq5b3wx9d
We figured out the entire strength of the coatings cannot simply come from metal-metal bonds. There was someone else in play. When a particle (copper here) hits a substrate (aluminium), the substrate also deforms and it gets squeezed between particles. /2
When the bond fails, copper-aluminium contact fails as well as the squeezed bit of aluminium, which gives the additional strength. /3
How I got into Surfaces? By chance. I had a PhD offer on laser material processing but my supervisor decided to take a PVC job so he introduced me to Prof Graham McCartney and Prof Phil Shipway. Phil had the first EPSRC grant in the U.K. to build a cold spray system in 2000. /1
I was hooked. I could not have asked for more supportive supervisors. One was Cambridge trained tribologists and other was Oxford trained metallurgist—a great combo to deal with surface engineering problems. /2
Question for you all. How did you end up in your work/research/study area? Did you plan it well in advance or just by chance? Did you switch fields? /3
This is a simple temperature velocity diagram diagram which shows how cold spray fits in with the rest of the spray technologies. In cold spray, particle velocity ranges from 400-1200 m/s and the temperature is maintained below the melting point of the material. https://t.co/NwgHWv4Yw9 https://t.co/ekeMs2kqEG
RT @RealSci_Nano: 👋 all, welcome to the week of “magical surface”. I will make a proper start tomorrow. In the meantime, I am posting my fi…
RT @StemCorps: Looking for an African American scientist working in photonics, optics or nano related physics work. If you know of anyone l…
Hello everyone, Hope you all had a great day! I have finally managed to squeeze in 15 minutes between putting a toddler to bed and microwaving dinner. A little bit more about how I ended up where I ended up. /1
I have a UG degree in Mechanical Engineering and a PG degree from @Uniofnottingham in Manufacturing Engineering. I stayed on and decided to do a PhD in Materials Eng. My masters thesis was on understanding bonding in cold sprayed copper & aluminum with a simple heat treatment. /2
The idea was if you can apply a low temperature heat treatment it will form intermetallics where there is atom-atom contact. I loved the idea so much I stayed on to do a PhD in cold spraying of titanium, funded by TWI. /3
Following PhD (& 5 decent quality journal papers) I went to @CranfieldUni for a Research Fellow in Energy Materials where I was exposed to power plant & gas turbine coatings. I was developing over 24+ plasma and high velocity oxy-fuel (HVOF) (more about those later) coatings./4
I was introduced to high temperature materials, biomass combustion and how to develop coatings for the next generation of power plants which are going to burn biomass. There was also this idea of USC (ultra supercritical power plants) to make carbon capture and storage viable. /5
I worked in a range of EU FP7 and TSB (Technology Strategy Board) projects to look into coatings to make USC boilers viable. Power plant heat exchangers cannot cope with nasty species like sulphur and chlorine at high 700 C+ temp from the biomass or other fuels. /6
I was developing these metallic and ceramic coatings to protect these tubes. In 2013, I headed back to Nottingham to take a fixed term fellowship in surface engineering to get back to developing coatings rather than destroying. I left a permanent job & a lecturing job for it! /7
I came over to build the UK's first suspension and solution precursor thermal spray facility, which means instead of using 5-45 um powder we can use 10 nm to 5 um particles. In 2015, I was appointed as an Assistant Professor in Materials Engineering & in 2018 as Associate Prof./8
GE has a brilliant video of Cold spray. How they use a cold spray with two robots to deposit tianium onto leading edges of a fan blade. The video is from https://t.co/CvPjldLrpi https://t.co/a2z2V50DdG
I was working with commercially pure titanium powder in my PhD. I was making titanium coatings for biomedical implants (the hip replacement part) and aerospace components (aero engines). Titanium is biocompatible since it has a protective titanium dioxide and it has low density/1 https://t.co/E2Bp34VpHe
Low density means, aerospace sector loves it. It is lighter to fly. It is hard to spray titanium using other techniques as it reacts with air (oxygen) and loses it wonderful properties. I was using a cold spray (like firing bullets to a surface) which had no heat, no melting. /2
The problem in those days used to be porosity or holes in the coating. The deformation of the bullets (titanium) was not complete so we ended up with holes. I was using a laser to melt the top surface to seal it, which dramatically improved the properties. /3
Also, titanium is excellent for salt water corrosion so the coating is needed in many process plants and desalination plants. Want to read more here is a paper https://t.co/8zKOkF2TWd /4
I also wrote a review on titanium. It was mainly for the literature review of my thesis. Here is a link if you fancy https://t.co/MBfQypgRhd
I am seeing a lot of views in the twitter analytics but I not seeing much engagement from the followers. What would you like to hear about? Do you have any question about me or surfaces? I can try to answer.
My first ever high pressure cold spray rig. It used to operate with helium at 29 bars and a gas heater to heat the gas up to 500 C. The convergent-divergent nozzle is mounted on the frame and the x-y table moves the sample. Pretty simple setup. 6 PhDs competed worth that rig. https://t.co/miHriY0brJ
We will dig deeper into this diagram and will talk about each of the techniques today. Thanks for those who engaged. I will try to answer the questions real soon. https://t.co/bM8wZiCBO9
A timeline for thermal and cold spray technology development courtesy of @ASMcoatings in Journal of Thermal Spray Technology https://t.co/3NjSbVdPOb
A full picture over a century here https://t.co/vFZF6NJsNO
RT @r1cc4rd0: Great tips! We wrote down our experience organising an online conference here https://t.co/MgVttwGXoe and here https://t.co/E…
Let's talk about Thermal Spray--now 111 years old. It is a group of technologies which allow a powder/wire feedstock to propel toward a surface using a heat source. Swiss inventor Max Ulrich Schoop submitted 2 patents in Germany and switzerland in 1909 for "metal spraying". /1 https://t.co/JGzRsmUkzU
There is very good article on the history of thermal spray inventor here. You can see the basic concepts in the photo. In one, he was repairing a 300 PS airplane motor & in the other one he was demonstrating spraying of steel. https://t.co/ef80Jg5b7j /2
How big is surface engineering and advanced coatings in the U.K.? Many of you may never heard of it. According to SEAC SIG report the UK’s surface engineering coating industry is worth over £11 billion and affects products worth £140 Ben. That a lot of 0. https://t.co/XmK3bQp32B https://t.co/t35t0JNby8
Where do we get coatings? I have copied three photos to give you an idea. The pistons and valves in your car engine are coated, the marine vessel are coated so barnacles don’t grow, the tablet or phone screen you are using to read this is coated, even the window glass too. /2
Without surface engineering, there would be no power generation, no flight, no travel. Even the cassette of your push bike is coated so it doesn’t wear out. The hip replacement part in the body are also coated with hydroxyapatite or bioglass coatings /3
I realised I have been allocated this account during the week when there is a strike going on in the U.K. universities for pension and workload. Apologies for breaking digital picket line. I hope followers all over the world are aware of the situation.
@IAndreuNano Very good question. For mechanical integrity, we would start with preparing a polished cross-section after cutting it with a diamond disc. We will measure microhardness and fracture toughness. Depending on the coating thickness we can do adhesion test (glue a dolly and pull it)/1
@IAndreuNano If we want to more sophisticated we can measure uniaxial or rotating bending fatigue test of the coated samples. We can also make free standing coating and measure using a small punch creep testing its high temperature properties./2
@IAndreuNano There is also non-glue based adhesion testing like laser shock—you pulse a laser and see at what laser power the coating delaminates./3
RT @IAndreuNano: @RealSci_Nano How do you test for the mechanical integrity of coatings? And how do you study the interface between the deo…
@a_baobeid Cold spraying is widely used for magnesium alloy repair for the aerospace industry. A large chunk of US market is based on repair of magnesium components for helicopter engines using cold spray.
RT @a_baobeid: @RealSci_Nano I am working on magnesium materials for biomedical implants and novel methods for 3D printing, I just came to…
Time to talk about various spray technologies. Let’s start with Arc spray. Here a pair of electrically conductive wires are melted by means of an electric arc. The molten material is atomised by compressed air and propelled towards the substrate surface https://t.co/gKPwOfT51j /1 https://t.co/yM5a1KVpbF https://t.co/1l2o6uOHGk
Arc spray particles are travelling relatively slower and cooler but the coatings are usually denser than the wire flame sprayed coating and higher deposition efficiencies. Examples include mostly corrosion and wear coatings for large components. https://t.co/crVdVvkZwN /2 https://t.co/y9jyWdoNcz
Aerospace companies in the U.K. uses a version of wire arc spray for metallizing polymer composites, for plane wings. These are deicing coatings based on joule heating—pass a small current and it will melt the ice. /3
Flame spray, a low cost option, with similar particle velocities to arc spray but much higher particle temperature. Typically we use oxyacetylene flame or hydrogen flame (3000 C). Fig courtesy of Gordon England. Also known as a low velocity oxy fuel spray. /1 https://t.co/yM5a1KVpbF https://t.co/C0EvYMro1f
We have an @OerlikonGroup combustion flame spray https://t.co/cMc7OFoROz . Instead of coating my colleague @Dr_Ifty_Ahmed uses it to make porous powder. /2
A combustion flame spray in action https://t.co/AvW7DJz3dq /3 https://t.co/TAYVRKDye2
Typical materials include: Aluminium, zinc, stainless steel, bronze, low carbon steel, nickel-based materials, molybdenum etc. The coatings industry is very much IP driven so very cagey about sharing knowhow. /3
Hope you all have a wonderful Wed. I am going to start tweeting about the two high end techniques : HVOF and plasma later today. https://t.co/yM5a1KVpbF
[admin] “Surfaces made magical with Nanoparticles” More details on podcast episode 42 featuring Tanvir (@tanvir_h) https://t.co/57XLvn5iVH
RT @StemCorps: @WolframJoy @JoaopoMartins @J_dasNeves @mfuentefreire @FlorindoLab @NazendeGT @popatlab @LuisSan48041402 @flaviacmsousa @rut…
I am back talking about HVOF (High Velocity Oxy Fuel) thermal spray—the industry standard process for cermet (ceramic+metallic) coatings. The particles are travelling much faster here but temperature cooler than plasma spray. It’s essentially a rocket engine burning O2+Fuel. /1 https://t.co/XNS7rk1p0O
The combustion here is supersonic so one can see the shock diamond in the flame. JP5000 is an industry standard HVOF torch. There two types of HVOF spray, gas fuelled and liquid fuelled. Gas fuelled torches can spray ceramic powder and the particles are injected into burner./2
Liquid fuel or kerosene fuelled guns are much more powerful (250 kW) but the particles are much cooler as we inject the powder in after the nozzle (cooler part). Tungsten carbide cobalt and chromium carbide nickel chrome are two popular coatings for HVOF /3
WC-Co is used for <500 C and CrC-NiCr is used >900 C in your plane engine to protect from wear. We need a finer cut powder 5-38 micron here where the carbides could be Nano sized <100 mm. /4
Polished cross section of a HVOF sprayed coating onto a steel substrate. https://t.co/VWaQmYQKWI https://t.co/FH21R9HLpo
HVOF thermal spraying of NiCr-Cr3C2 using MetJet IV in our lab. It can be very noisy due to supersonic combustion https://t.co/XsVD8BsKRJ via @YouTube https://t.co/41PMDnwNJE
There is a beautiful world out ther on HVOF sprayed splats and microscopy. One from my colleague Prof Kuroda https://t.co/yZJQ9rZYaE https://t.co/Jw3ilMVMIJ
@TEMguru TiN is still mostly deposited using physical vapour deposition. For thicker TiN plasma spray is used https://t.co/pjykysC6zL
While we are going through this #COVIT19 chaos, imagine if we could design a cheap and effective surface which would kill all the nasties without harming humans. We have lots of anti bacterial coatings for use in hospitals containing copper, silver and galium oxide.
What a week! Many universities in the U.K. have cancelled face to face meeting from Mon and we are transitioning online from 23rd March. Sorry for the slow tweets. I have also lost a close aunt this week (not due to coronavirus). I will try my best to catch up.
Where is this nano in surface engineering? Thermal spray is mostly micron scale business but nano came in 1990s and it opened a whole new world for us. We call it suspension thermal spray (STS). Instead of using powder we can use a suspension with nano particles./1 https://t.co/CRaNTM0ve3
The benefits: finer particles result in uniform properties in all directions and the hardness can be increased significantly which is good for wear. You can see suspension thermal sprayed alumina coating here. /2 https://t.co/tyY3J2PZtu
You can improve the wear performance of alumina by an order of magnitude by using suspension (nano) over micron sized powders you can see an AFM image showing how hard these particles can be./3 https://t.co/0agDWxvGV5
Link to our first suspension thermal spray work https://t.co/m1Z0vS0m88
A suspension high velocity oxy fuel thermal spray setup to spray sub-micron to nano range particles. We are spraying cerium oxide here to make surfaces super hydrophobic. /1 https://t.co/NzGCTGrPDv
Benefits: water would roll off easily. The surface can be self cleaning. Also bugs wouldn’t grow if the water doesn’t stay there for long. For icy conditions, if water doesn’t stick there won’t be any ice—a great idea. More details here https://t.co/BVws2uFAAM /2 https://t.co/dzKzfcDCdK
Continuing the theme of suspension spraying, one can mix nanoparticles like graphene nanoplatelets with sub-micron alumina to make beautiful nanocomposite coatings. Cross section images below. /1 https://t.co/kYP5MA1d0h
Using a spectroscopy like Raman spectroscopy one can measure the vibrational modes of the molecule which can tell us how many layers are there in the graphene nanoplatelets after the spray. Carbon has D, G & 2D peaks. More about Raman https://t.co/WDWUE7vbh4 /2 https://t.co/dF6hJox3W7
There is a barely a scratch on the sample which was sprayed with graphene nanoplatelets, compared to the sample which was pure alumina after a wear test. Details here https://t.co/cx3ufc4aLs https://t.co/X97zwy0lKZ
Breakup of a suspension in a plasma is a beautiful process. Look here. When fine particles are injected in a plasma they behave very differently. They follow the gas trajectories. /1 https://t.co/piNLqaXpk5 https://t.co/z0vxqvJ8qa
SPS (Suspension Plasma Spray) setup. These fine particles hit the asperities of the substrate and form beautiful columnar structure. These columnar structures are highly desirable for thermal barrier coatings for aero engines. They can expand and contract better in service/2 https://t.co/ui6JXWkFdm
These columnar structure could only be formed using a very expensive process called EB-PVD (electron beam physical vapour deposition). We can now form these using a much cheaper SPS process—thanks to nano particles. https://t.co/Pn5vaJ2lLx /3 https://t.co/YSlhdeXwiH
[admin] Thank you Tanvir (@tanvir_h ) for a wonderful week full of science! listen to the podcasts where Tanvir explains his science - https://t.co/57XLvn5iVH
Thomas Swift
[admin] "Using & Abusing Smart Polymers" Welcome Thomas Swift (@Swifthom ) for a week of polymer science Listen to the podcast to know what is coming your way https://t.co/6euBRPoAgg
RT @Swifthom: Login details for @RealSci_Nano have just arrived. Need to serve the family breakfast first, then see where we are
Hi everyone, I’m a Lecturer (Assistant Professor) in Polymer Chemistry at the Uni of Bradford. My work focuses on Functional Polymer Materials; which means I get to dabble in many different areas of research. So should be something for everyone this week (Chem/Bio/Phys/nano)
I originally did a Master’s Degree in Chemistry, so I was trained to look at the world on a molecular level. But for people who scared of chemical structures – don’t worry, even Brian Cox struggles with these so I wont go overboard. #canyouspotthemistakes? https://t.co/RsZVUgUhkr
With the coronavirus spreading am isolated and working from home (this was taken by my wife on Wednesday). We're lucky enough to have a big window to look out of. Hope everyone is staying safe https://t.co/bS1Zaomt3p
So, I work with polymers. Polymers are important and they affect everyone. Polymers are great but, when I visit schools / do public events I’m always second guessing myself about how much I need to explain – do you actually know (or at least think you know) what a Polymer is?
This - so much this. The temptation to go 'you know plastics' is always there but its just not all encompassing enough for what I really want to explain https://t.co/uWa1qIFAWt
I'll leave the poll open but fairly even split so far - which is kind of what I expected. We'll leave it open to see how more people feel. Polymers are 'big molecules' - they are difficult to explain in just a few sentences without it sounding glib but I aim to explain this week https://t.co/Vp0OSiJhhh
The criticism is fair but also needs putting into context. Nothing is 'good' or 'bad' and use of plastics something I'll discuss this week (probably the abuse part of my title). But if any the general populace have made the connection I'd take that as a step in right direction https://t.co/oZZP8hyJ91
So, I am a chemist, and my team make and tests 'big molecules' - which means we do most our work in laboratories dressed something like this. Learning to handle chemicals safely and operate in this kind of environment is one of the most fundamental skills we teach our students https://t.co/QP9eAQkljS
This is our first week of 'full' antiviral isolation in the UK (we've been shutting down the labs for a while but it had to be done safely). Right now I am (like many people) stuck like this. But teaching continues online (more about that later) and I have plenty of writing to do https://t.co/ArbSaGgjK0
The only downside is I can't go into the labs and take and photos / video specifically for you. But it's fine, I have been working on my 'graphic design' skills and I can talk about polymers on the 'nano' scale with pictures. https://t.co/COlZ5rRHhx
When I talk to another 'materials scientist' they might think of me as a 'Soft Matter' specialist. But what exactly is Soft Matter? Well, as my students know, turning straight to a textbook can be more confusing than its worth if your don't prepare https://t.co/KPfn04mjDP
Soft Matter - essentially - exactly what you think it is. Squishy stuff! Anything hard usually has some sort of crystalline structure (think of coal or diamond) opposed to other forms of carbon (i.e. Skin?). I tend to stick to the more flexible end of the spectrum https://t.co/GHBkMhQ9pg
My specific speciality is 'SMART' materials... But how can we have 'SMART' polymers (re... the thing that plastic is?) Are they useful (YES!). Are they safe? (PROBABLY). Will they become sentient and take over the world (NO, BUT WE CAN DREAM) https://t.co/Ryi8gSqz3d
I’ve a rough plan for this week, on Monday I want to explain ‘molecularly’ (don’t be scared) why polymers are so unique – and how we can use this to make them SMART. This is a critical component of some nanotechnology but sometimes even the scientist forget the basic principles. https://t.co/LlsqsA4pmD
On Tuesday I want to talk about how I got into academia and focus on research in academia / industry relationships. Getting here wasn’t planned from the start, and I wouldn’t call my route to HE ‘weird’ but I’ve had jobs never dreamt up in school 'career planning' sessions
Wednesday is going to be plastic pollution day. As a polymer chemist we can’t avoid facing the dark truth that plastics are doing a lot of harm. Is it inevitable? What can we do about it? What are the solutions and will they work #reasonstohope https://t.co/79Xkz5Gzap
Thursday: my work on soft matter characterisation. All the stuff that bothers me happens at the nanoscale (i.e. ultra small) so what techniques do materials scientists have to examine the really, really small stuff? For polymers that’s even trickier because they won’t stay still https://t.co/tSBmG3d0Lp
Friday – with #Covid-19 everywhere it’ll be time to talk about the work I’ve been helping with materials for infection diagnostics. Most the work we have done so far is bacteria based so can’t promise any solutions to this pandemic BUT #antimicrobialresistance is still a problem https://t.co/30l2lJHD2e
All the way through would love any questions anyone has about polymers. I might not have the answers but that’s why I’m still researching. Quoting Dara O’Briain ‘Science doesn’t know everything, because if it did, it would stop.’ That's not going to happen anytime soon https://t.co/oSa5YepvYE
So, you might ask exactly, what is it that a polymer scientist does? How am I useful to society? Have you well covered here - I've been involved in loads of project over the last decade almost all of which have something exciting about them https://t.co/ufPtrOO1kJ
Topical right now - these are prototype soaps reformulated and developed in our laboratory. A local manufacturer was having trouble with their formulations and needed some trouble shooting so last year we set up a prototype soap manufacturing reactor in our lab to help out https://t.co/vfCZIANMbP
These photos are of 'uncured' (think like uncooked dough, not yet the finished bread) wound dressings. We've been tinkering with additives to make plasters more 'breathable'. Prevent sweat build up beneath them makes them more comfortable to the wearer. https://t.co/HQ8TiV1N2e
I plan to discuss Friday our prototype swabs that 'indicate' the presence of bacteria. Imagine going to your GP with a sore throat, breathing into a tube, then being told within half an hour whether or not you should get antibiotics rather than 'if not better come back in 3 days' https://t.co/p4jznDe92H
These are 'flocculants' in action - polymers used to clean water supplies. I've been out to sewage plants to test the polymers used to clean tap water. See the horrible 'muck' on the left separate out and sink down to the bottom on the right. My PhD was based around these https://t.co/PH4TQcIHMK
And, back before studying for a doctorate, I spent some time working for a paint manufacturer, this is one of the only photos I have from that glorious time trying to improve the 'weathering' of paints. Paints use polymers, its what holds them together https://t.co/fEfQXhhYD1
There are more examples but, most the time, we're just sat in a lab making cool chemicals and testing their properties. Make, test, repeat. Endless make, test, repeat. Anyone can do the leg work but fitting it all together is where it gets exciting (my students may disagree) https://t.co/VwwmFBEFH9
Retweeting for a potential American audience perhaps? This was 50/50 earlier and a sizeable contingent still unsure about polymers. Well this week we will challenge that https://t.co/Vp0OSiJhhh
I would never go as far as to say cell biochemistry is applied polymer science, as I'd likely get lynched, but the overlap is there. Proteins, enzymes, DNA, are masterpieces of polymer design that us synethic chemists can only dream of aspiring towards https://t.co/L0fugRCbjr
But I delighted in the stunned silence in a class when I turned around half way through a lecture on colloids (Physical Chem I. E. Maths), pointed at a membrane diagram & asked the room 'Does anyone know what that is? You' ve all seen it before... It's the start of a cell wall' https://t.co/KD49c4tbzk
It's 8.30 am in the UK and today we are going to discuss exactly how we can make 'smart' materials. There will need to be chemical diagrams but only friendly ones https://t.co/Ymp2nXd86b
Okay, first principles. The universe is made of atoms. For 'just' a moment lets forget about electrons, neutrons and protons, and say that this is it. This is the basic building block. We'll label different atoms by colour; so lets say Oxygen is red. It looks a little lonely https://t.co/aOyquV4gkh
So the atoms stick together in groups. Here we have two carbons (grey) and 6 oxygens (white). This is quite a stable 'family unit' (Why? Because of all the electrons, neutrons and protons that I am not going to discuss). This is what a molecule is - just a stable arrangement https://t.co/qI7Czld7xN
Some configurations become useful molecules. This is methanol - great at disinfecting surfaces and distilling into alcoholic beverages. It just has one oxygen, a couple of carbons and six hydrogens. That ONE extra oxygen has made all the difference https://t.co/iHG5enIo1S
So, I will move on, but some great examples of functional molecules are Caffeine - the component of tea and coffee that gives you that buzz. It's 'usefulness' comes from this particular arrangement of molecules. It's still just carbon, oxygen hydrogen and now nitrogen (the blue) https://t.co/wqtcgqhn8Q
Or, a fun favourite, Glutamate - something your body produces to regulate FEAR! This is a great molecule but it's just one simple structure. At this point we're just painting by colour https://t.co/FFgjYko1ad
My final example of a small molecule is Vancomycin - a 'potent' antibiotic. Doctors do not like prescribing this unless they are certain it will work. Antibiotic resistance is a story for another day. All you need to take from this is 'this arrangement of atoms = bacteria death' https://t.co/mGG7BPvqvh
The bigger and weirder molecules are great, however do not mistake 'complexity' for 'intelligence'. By and large they all just hang around, doing their own thing, waiting for something to come around and react with them. They are passive. https://t.co/GwCkBEZIRV
PSA. I typed methanol, the picture says ethanol, it is ethanol. I am a failed chemist. This is what you get for uploading before your morning coffee https://t.co/xPOnFUD3mJ
@schrodingerskit Well spotted. The molecule is properly modelled and rendered. The bacteria is just a background photo. Sadly working on a budget image editor wise. The bacteria will be HUGE compared to the molecule - it'd be smaller than a speck of dust to them. https://t.co/mq9TUMvjG1
A family of molecules can have a set purpose but as they get larger they do not get 'smarter' - they just get more specific. Specific is good - we want cancer drugs that kill tumours but not us. But specificity is not smart it is just good programming
A quick analogy. There are a class of molecules that eat burgers (there aren't). I can make these molecules, spread them around, and the all worlds burgers will be gone. https://t.co/HEo4gXUKkX
I can modify the molecule to take out specific brands. We could make it 'only' like Burger King burgers. Then McDonalds, Wendys and all the others would be safe. The extra complexity (see vancomycin) has not bred intelligence it has bred a fussy eater https://t.co/fDadaz68UM
If I want really smart molecules biology has been doing this for billions of years. Here is a great example: Hemoglobin - the most important part of your blood. It can carry up to four oxygen molecules and carry them around your body to where you need it most #vampirealert https://t.co/jI6YUU0SO1
Yes, Hemoglobin IS smart. The more oxygen it has the more generous at sharing it is. The less it has the more choosey it is about letting that last one go. It is a conscientious delivery man - serving to where it is most needed. https://t.co/EL5Ea7YvcV
It does this by changing its shape. It stretches / reorganises as it goes around its delivery. It is always the same thing, the same atoms stuck together in the same way, but it switches around to look like something completely different. It is a molecular transformer https://t.co/Gem1SDorcx
@schrodingerskit Okay, sorry. How Hemoglobin specifically works is a bit of a detour and not my specific area. It carries air from lungs to rest of body by changing its shape is all I really want to impart https://t.co/dGs0nJKjyB
Biologists know that smart molecules tend to be big molecules. For them this is usually about encoding - think of DNA, a sequence that contains written instruction for 'life' as we know it https://t.co/xJaJ8d3wfl
But being big brings other advantages. It brings flexibility, it brings the ability to bend and twist and turn. This is often just as important as the sequence (re programming) and often gets overlooked. https://t.co/KMXVnvWzXd
Poll results are in - as expected a hefty dose of people don't know what a polymer is (and it will biased as this channel caters to people with 'interest'.) Excellent to hear and good timing - I'm just at the point where we drop the biology and start talking about polymers! https://t.co/Vp0OSiJhhh
It is time now to start talking about polymers. This is what I study and teach about. This is where I try to bring some of that biological 'smart-ness' to bog standard molecules. It is time to explain what a polymer actually is https://t.co/3lVC53adg9
A polymer is a BIG molecule, it is a long chain of repeating molecules strung together. On a molecular scale it is huge but by volume they are only a couple of nanometers wide (100,000 times smaller than a human hair) https://t.co/fDOkgoTOZD
Nature is VERY smart. It can write sequences of this chain with different molecules. The sequences dictate what the polymer can do, what it is 'for'. Does this enzyme promote hair growth or make you crave sugar? The sequence dictates https://t.co/yXavbBaPFI
But as human chemists we aren't so adapt at this. It is possible but expensive and time consuming. So generally even the 'best' forms of long chain control of most synthetic materials are just about blocks. Big, beautiful, blocks https://t.co/0IuugW2evu
But that does not mean we have useless materials. We can still make molecules that have control over their shape. We can develop materials that, on their own volition, stretch or retract to better suit their environments. THIS is what I study. https://t.co/CF8HUxnVNV
Why would a molecule want to change its shape? There are loads of reasons but the best example I can give is.... well... Water! It's so difficult to get away from, we live on a Blue Planet, and it drives EVERYTHING https://t.co/JkPoilUsZ2
I started this morning explaining we had to talk about molecules. Quick recap for anyone who missed it here https://t.co/sVkWCiDowB
So, this is water. Oxygen and hydrogen. I've stuck it next to four important elements (oxygen, nitrogen, hydrogen and carbon). One of these things is not like the others. https://t.co/9D2wYtH7tV
Water is everywhere. Not just as a physical thing but as a molecule. And it does not keep to itself, it likes to interact with other molecules, particularly any that contain plenty of oxygen or nitrogen. https://t.co/iageRLkQQu
Look at sugar - plenty of oxygen. That's why it can be dissolved in your tea. That's why we ingest so much and our food tastes sweet. remove the oxygen atoms and we'd loose that advantage https://t.co/amAKFZqdwy
This brings us to plastics. Usually long polymer chains with lots and lots of carbon. What specifically makes a polymer a plastic? Well, a lot of us (even in the industry) get confused about this. https://t.co/3Fuo37SG1A
The term 'polymer' indicates a long molecule, it indicates something long and flexible that we can manipulate. Most people hear about it because they hear about plastics. Most people 'think' a polymer is a plastic. https://t.co/cwpGNidCzH
Polymers are not plastics. Plastics are polymers. Officially plastics are things which are 'malleable and can be moulded into shape'. It is not a chemical term but a mechanical one. Is Jelly a plastic? Sort of. https://t.co/lDABvH75xW
So when you say plastics are bad for the planet (or rather that they are a big issue), I completely agree. But there's a specific problem here I want to come back to on Wednesday. https://t.co/sGzJyGbfzY
When we say plastic is bad to the planet we actually mean these long carbon-carbon chains are bad for the planet. https://t.co/QxRyii8iDj
Oooh, never seen that before. Probably because I avoid ANY tv/cartoon/movie that involves things inside the body like the plague. I had a run in with 'Fantastic Voyage' as a child that scarred me for life https://t.co/jzGYeLeIow https://t.co/TaswZeCIYc
Most polymers are a mix of carbon and other atoms. Every blue or red spot on this molecule is a site that 'could' grab a water molecule. Whether it will or not? Depends on its environment https://t.co/2SrK1JqIRy
If a polymer doesn't want to play with the water it can coil in on itself. This form of 'molecular isolation' can be inherent but some polymers can switch back and forth, changing their mind depending on the environment https://t.co/VAGy2nktyF
Why would a polymer switch? Temperature is a common one. Think of it like stretching out to get some sun on a warm day, or coiling up into a ball to preserve heat when its cold. https://t.co/UBFxaqs4ZY
The physics driving this (its entropy) are ridiculously complicated but the maths is sound. The polymer doesn't choose to unravel, it is responding to its environment https://t.co/ku434QdRgb
Another influence is pH - if the water is acidic the polymer might retract. Or salts, some polymers respond completely differently depending on what else is around them https://t.co/fzTldBr97Z
Lets take a step back. We can split out polymers into two categories with a grey area in the middle. Some polymers are 'water loving' - we call them 'Hydrophilic' https://t.co/4v6gGegD7M
Some other polymers don't like water at all. Plastics wont dissolve and wont bond with the water molecules. We label them as 'Hydrophobic'. They 'hate' water. https://t.co/kIRj3keU2p
We're at a point where we can 'finally' forget molecular structures and just describe things with these two terms. Water loving or water hating. Life, biology, chemistry, materials science as we know it can be essentially simplified like this. https://t.co/U9sTwUWepf
Sorry if this morning was molecule heavy. We're done now. I want to talk about why this is exciting after my teaching is over for today. Back in an hour or so https://t.co/Ib6E7ohXqL
Okay, all my teaching for today is done, I just need some tea and then we can continue. Something a bit more light hearted and exciting this afternoon following the molecules this morning
This afternoon will show 'why are smart polymers useful?' or 'all that molecular stuff was interesting but what's the point' or 'Exactly why do you have a job doing this?'
Hypothetical scenario. I have a colleague who is very smart and very worried about headaches. He has designed a drug that when it gets in the brain will sort everything out. https://t.co/iqgaY5Bb1i
But this drug is fragile, if you swallow it then your stomach acids will destroy the perfect structure. That is 'why' we have a stomach after all, to break things down and stop anything nasty getting into our bodies. https://t.co/L63aw9s2ti
This guy is smart but he's tried everything. Save taking a needle and injecting it straight into your skull the drug is useless. You could inject the arm and 'hope' it makes its way down the blood stream but for headaches nobody wants that https://t.co/tY94Rq1gY4
That's where we come in! What if we had a polymer that wrapped around the drug molecule. What if it held onto it so tightly it shielded the drug from the stomach acids? The polymer (which is pretty indestructible) could act as shield helping the drug through the flash point https://t.co/NifmMEEDIt
This kind of helping hand transport is really common, in fact 'controlled delivery' is an entire field within Pharmacy. Polymers can lend a hand to small molecules, help them get where they need to go then drop them off where they need to go. It's easy! https://t.co/w8txiXhg7i
With the right polymers you can target delivery of your drug somewhere warm - like an infection. The body will be heating up to fight off the infection and the polymer will 'carry' the drug safely until it finds the spot https://t.co/T4RB0Wg4c8
They are also good at fighting another problem. Your body is really, really good at getting rid of stuff it doesn't recognise. We get rid of drugs in our body the normal way we get rid of most things in our body https://t.co/ge28rgT70l
So, a lot of the 'drug load' is lost. It never reaches your brain / heart / infection / whatever because the body pushes it out. Polymers (because they are big) hang around. Our molecular taxi can just circle round the body, dropping a little here and a little there. https://t.co/f78KUSgSnB
Fed up of taking pills 6 times a day at regular intervals? Don't have the time or patience or micro manage every waking moment? Wrap the drug in a smart polymer, take 1 pill that's 4x bigger each morning and live free knowing your does up all day. https://t.co/CCL7U7nivn
How can polymers 'wrap around' small drugs? Often they do it in layers. I glossed over this but there is some really cool work on building polymer assemblies to form specific shapes and structures https://t.co/yX9KnwlvKk
The cosmetics industry latched onto this and started selling 'micellar cleansing solutions' a few years ago. A micelle is just a bubble of these 'hydrophobic' polymers layering up to get away from the water. There is nothing particularly special about micelles https://t.co/yfIZEenaRS
Not saying it doesn't work... But anyone can make a Micelle. You can do it to; here is a photo of someone making tonnes of micelles at home. Washing up liquid, soap, detergents - all of these are materials designed to bridge that hydrophobic / hydrophilic gap https://t.co/y6MMVTAURu
That's really beautiful work - love it. Self assembly is fascinating and a great application of why polymers are special. I think you'll like my next tweet then - just got to dig out the paper https://t.co/PpU6lGn5dF
@SusieusMaximus 'Why' is a word with a lot of pathos. When it does come up I tend to get either very scared or very excited depending on the situation 😀
I was lucky enough to work with a fantastic PhD who worked developing micelle delivery systems. She made these lovely 'onion' particles with multiple layers. Stick a drug particle in there and it would take hours to escape. https://t.co/R8p4mHN1Qg https://t.co/m6yW7JUZRZ
@DishPodcast These onion micelles took some careful, careful conditions to make but when she presented them to the group we were amazed.
@DishPodcast They needed quite smart polymer design, a branching architecture and control over molecular weight, then an overnight solvent switch to prepare them stable. Mess that up and she got all sorts of structures https://t.co/sBVon0JpJj
@DishPodcast But @StephenRimmer6 was the PI on that project, I just helped with the polymer characterisation. The paper is open access if you want to read https://t.co/R8p4mHN1Qg
This photo is an electron micrograph of particles too small to scatter light. Polymer chains are only a few nm large, they form structures often still under a micron in diameter. A human hair is 75 microns. https://t.co/b3XERSrD4c
I could spend the next 3/4 hours listing examples of polymers being used in important things. However there is a small prizewinning video that can do that for me from Yvonne Choo. It even has a song in it https://t.co/fyXiaS05WP
@yvonnechoo_sl - is this you? If so is a lovely video, and sorry to drag something up nearly half a decade old but the topic is timeless https://t.co/hK1gY1tgCL
So, it's dinner time and I'm wrapping up for today. Want to switch tack tomorrow and discuss the way polymers bridge the academic / industry divide in a way almost no other topic manage. No chemical structures. I promise
It's gone midnight in the UK but perhaps today's discussion might attract attention in the states? We started with a quick 'molecular' recap https://t.co/sVkWCiDowB
Then we acknowledged how far biology is ahead of us mere mortals https://t.co/c00AtLtgao
Then, finally, brought some polymers into the conversation. https://t.co/1XK5Uz6kaE
Polymers + plastic? NO, but we can't ignore them either https://t.co/TPqLedbzeL
So - this is how we make a SMART polymer? Yes, if by smart you mean aware of its surroundings https://t.co/RVMdiURPWG
Quickly define two key terms here. Are you a hydrophobe? https://t.co/8aSCalmbuI
Then we have medical uses. These stuff do wonders for drug delivery https://t.co/1Zk8PpC2PZ
And a great introduction to supramolecular assembly (or rather how we make 'stuff' from these things https://t.co/kkAW9Z6stT
A question to leave you with? A blanket statement but would love your opinion. Is corporate money welcome in Scientific Research? Complex question but I'm going to need yes/no answers
RT @yvonnechoo_sl: @RealSci_Nano Dr @Swifthom , you're right it is! This was made almost a decade ago when I just finished matriculation (A…
Going to start properly I'm half an hour but if you've finished your breakfast in the UK have a think about who does research and how it is funded. We have a poll: https://t.co/4kiKjVb5Vm
So - a poll I started last night shows most of us accept the principle of industry funding research, but there is a significant holdout opposed to the idea https://t.co/4kiKjVb5Vm
I am not completely surprised. In some areas of science (I'm thinking of climate change or big pharma) there has been scepticism of whether biased research could be unfairly skewing debates in a pre-determined direction. It is an emotional and highly charged topic https://t.co/kA32z5y5e3
But Materials Science... Well, I'm not going to say it's different, but we should understand the background of the discipline and why it is the perfect example of why academics should NOT work in silos https://t.co/MMtoJnjejg
I would like to take a moment to acknowledge Hermann Staudinger - the 'father' of polymer science as we know it today. He gave birth to this discipline less than a hundred years ago - you can read about his discoveries here https://t.co/LXyOpN1npY https://t.co/MfyNoHTsjd
But, though he codified the rules and concepts of polymer science, the origins of the discipline go back further. In fact to nearly 180 years years ago. Something happened in 1843 that codified the need for Materials Scientists. Something significant. What was it? Here's a clue: https://t.co/gte1oO9azy
In 1837 Queen Victoria became queen of England and ushered in a new age of modernity in Britain. The Industrial revolution had reshaped the world as we knew it - this was a time of thriving industry and mass manufacture. The world had changed https://t.co/wgGAzX2W5K
America was still 20 years pre civil war and undergoing massive expansion. A war was brewing with Mexico but it was enjoying the roll out of electrification. https://t.co/XlzS9hOoHL
This was an age of inventors where you could 'just about' make a living experimenting and testing new products. Enter Charles Goodyear - a struggling scientist who, after suffering bankruptcy, moved from company to company offering his chemical expertise https://t.co/wtYffOxwf8
Meanwhile in the UK a wealthy coach builder who made a fortune shredding rubber scraps and recycling them. You heard that right - we have been 'recycling' plastics for almost 150 years - this is not a new concept. But it was a lot less sophisticated then https://t.co/IMm1qCUtCs
1843 was set to be a very difficult year for Thomas Hancock and Charles Goodyear. Both were doing some 'very' important work that would reshape the world and both of them had a similar idea https://t.co/rql8h11PAd
Patents are ways companies can declare new inventions without the risk of being copied and undercut. It is a very important, and potentially expensive, legal process. It is the legal professions way of protecting inventors to ensure they get credit and compensation https://t.co/OnAtdGNAi1
It doesn't cost much to file a patent. But it might cost quite a lot to defend one. So, the system is potentially unbalanced, but at least it does give protection. We all want to get paid for our work. https://t.co/Ejyvy8MaSk
Speaking of credit I am going to have to thank @BBCFOUR @markmiodownik - some of these pictures I'm going to use come from his EXCELLENT show 'How it Works'. If it's ever repeated somewhere you can find it then I highly recommend watching https://t.co/hMBK84vOgA
Pre 1843 - there was a problem. 'Rubber' was an important natural material that was being incorporated into many products. It was an excellent 'waterproofing' agent, it could be processed, moulded and factories - but it had problems. It was not quite 'rubber' as we know it today https://t.co/lU0c0rQNIQ
Yeah, sorry, I continue here https://t.co/YAtrTNfPTH. I run threads for a certain length but when I switch topic I tend to start a new thread as the 'audience' for each successive tweet tends to shrink slightly. But if people would prefer one giant mega thread let me know
Rubber is an elastomer. It is soft, stretchy and flexible (great) but it also goes 'weird' if you heat it up or cool it down. Bad news if you are using it to waterproof your coaches or mailbags. Cold winters or hot summers = need to replace it every year https://t.co/mbDSkKyCp6
Hence the need for scientists and inventors to 'modify' rubber. We knew that we had a great product here, it just needed some minor modifications to make it perfect. There was money to be made https://t.co/H6wj2KrJ7v
And, as some of you have guessed, this is the point where someone dropped sulphur and white lead into the rubber before it was processed. It turned bright white, very sticky and very hard. It was still rubber but it was completely different https://t.co/AsksZFPIy1
If you then heat it up (i.e. cook it) the product turned black, not sticky and much more stable. It also stopped going 'weird' if you let it get hot or cold. It was the birth of a new class of materials. It may not look like much but it really was revolutionary. https://t.co/uUIMuDgII3
We 'think' Charles Goodyear was the first person to do this. He knew he was onto something big, he knew this was important work that could change the world. His mistake was to tell and show other people what he was working on before he was finished. https://t.co/OCVwPils0M
Fed up of replacing his rubber British entrepreneur Thomas Hancock was keen to solve this problem. A friend of a friend showed him some 'American' samples of prototype materials and he immediately saw the potential. All efforts were rediverted to solving this issue https://t.co/SE53QRndBx
In 1844, completely separately, both men filed a patents for the 'vulcanisation' of Rubber. First Hancock in the UK, then 8 weeks later Goodyear in the USA. They were working separately, unaware of what each other was up to, and they both wanted to change the world. https://t.co/UegbCYfPfv
But if you were a patent lawyer, if you were called in to look at this problem, how would you distinguish if one of them had 'stolen' the others work. Who is the expert who can explain what this miraculous discovery is and who deserves the credit? #teamgoodyear #teamhancock https://t.co/dfeZtwiRUf
Apologies for the delay. Am going to break my promise - I have a quick simulation running and a chemical structure is on its way. https://t.co/Ep3OSVMMmj
We now know, with hindsight, that vulcanisation is the process of using sulphur 'linkers' to hold together the rubber chains. It is taking the individual polymer chains in the natural product and turning them into something strong. In polymer science there is strength in unity! https://t.co/NI8lRbUns7
From a modern materials science perspective they converted something chaotic and uneven into a smooth, almost crystalline material that is strong but keeps its flexibility. These are electron microscopes that are magnifying the rubber surface over 1000x https://t.co/BVmqq6mMjj
So what happened to Hancock and Goodyear... Well, it's a little sad. Charles Goodyear set up companies, fought for his invention over the 1840s and 50s, lost the court battles and died in 1860. He seemed potentially at peace with his misfortune writing: https://t.co/20mncIXxU9
The Goodyear Tyre and Rubber company was set up almost 40 years later in honour of the man. This famous brand, still going strong today, had nothing to do with him but wanted to honour his good work. https://t.co/PIGpVz3Wz1
Thomas Hancock, who won the patent cases, went into business with Charles Macintosh (the Rain Coat manufacturer) and their business is still going strong today. He did later admit that had he not seen the Goodyear samples he would never have got where he did as quickly. https://t.co/Rs77eT5Ho2
I've just written quite a lot about how the need to develop waterproof clothing dragged materials science into the legal framework. It's a pertinent, and hardly unique, example of how our modern, industrial world has always depended on scientific discovery https://t.co/YAtrTMYev7
Without Materials Scientists we would not have developed the celluloid that drove the ascendency of the Hollywood Film Industry, and at the time they were originally paid to make Billiards Balls https://t.co/jEjwegtftf
So without industrial investment there would be no movies, televisions, touch screens, modern phones... All of these inventions are driven by scientific progress and a LOT of industrial support. We are not living in the digital age - we are living in the polymer age! https://t.co/EWPaQMyBWX
(Okay - I am biased there). But I do not work for an industrial company, I work for a University. I do 'pure and applied' science and I know incredibly why it is SO important to have people able to distance the work we do from industry
As I mentioned on Sunday I used to work for a paint manufacturer. I did a LOT of work for them. Great work, good science, powerful stuff. However all I have to show for it is this photograph and good memories. When I left I had to hand all my research in and walk away. https://t.co/IGbsy1peJ7
Academics have a role to play in building up the shared knowledge of society. Work done behind closed doors will be lost to time eventually - especially if the company shuts down. They patent discoveries but that is usually about protection and not for the purpose of 'sharing' https://t.co/mUDz3qyEHN
We do this by a culture of publishing our work in scientific journals. This is quite a fraught process, and its led to a lot of conversations about how weird academic culture is, but peer review is our best method of sharing good science with the world https://t.co/bFYhzz35YL
Governments around the world all have a system for incentivising good research. The work we do is good for the world, good for science, it brings prestige but it also quite often makes money in the long run. For countries looking to invest and profit science is not a bad gamble. https://t.co/jiHoqxcP9R
Over the last few years there has been a drive to make our work 'open access'. Publishers collate our work in pay to access journals - but if we are publically funded what we do SHOULD be open to everyone right? https://t.co/g0YgkBu3HV
This is a great thing but I am no evangelists. Paying to make the articles free for everyone means paying up front. It can be expensive, a cost on top of all of the VERY expensive laboratory equipment and research time. So many of us are working on a budget. https://t.co/7ynDLHJlbv
People under estimate the importance of paint. We used to say whatever happens, even if the end of the world comes (this was a decade ago) people are always going to want two things. They're going to want toilet roll, and their going to want to paint their houses. https://t.co/Oa4mnY9Nny
Admittedly there's been no news stories about the rush on paint in DIY stores recently but... yeah. Nobody likes ugly walls.
According to the scientific metrics this is my best, most important work so far. And if anyone in the general public wants to read it they can, free of charge. But don't expect a page turner. https://t.co/zBmLzDFJRp
But even with open access, as an academic if I do good work, publish, then stop there I haven't really changed anything. The world has not substantially improved - all I've done is shown a discovery. You need other people to pick up your ideas and run with them https://t.co/OnEWS8k4UH
In science, particularly Materials Science, Academics proper by having a close relationship with industry. They want to know what we are doing, of course they do, because they want to make money. But we need to know what they are doing otherwise society as a whole misses out https://t.co/v15xZ7XFEG
Not saying this is the only way, and any young academics out there wondering 'But I don't know any rich business executives' - don't worry. The world is a big place - publish what you can and people will take notice. These relationships can take a decade or to mature https://t.co/O9UMAfowmi
So, for the ~20% of you worried about corporate cash 'influencing' academics. The world is a big place, and there will be some bad people out there, but most of us are not in this for the money. https://t.co/4kiKjVb5Vm
Okay, break time. Back in an hour to highlight some of the areas that most benefit from academic - industry collaboration.
I've seen loads of stuff like this and its brilliant. Also - direct them to find threads like this and @realscientists - a new face and a new topic every week. https://t.co/NTZ0EZtRqM
A few more points for today then. I want to talk about the work Materials Scientists do that we 'hope' industry will pick up and use to make the world a better place. Science that, is essentially 'good research' but would be almost pointless without the commercial application
Solar energy is a common theme in materials science. Taking energy in the form of light and converting it into electricity. Plants are very good at this (photosynthesis) and we are getting better every year. https://t.co/K0kOWZjEND
There are excellent materials for turning the light 'into' electricity but the problem is moving it around. One of my research interests is using polymers to do this. SMART polymers (see yesterdays tweets), with antenna on them, can grab that energy and move it where you want https://t.co/O6vsMWkzrK
To simplify most systems can only work with a specific 'energy' of light (i.e. a very specific colour). They are 'quantum' systems. But all 'Quantum' means is 'specific'. Sorry Sci Fi Fans - it's not as exciting as you think it is https://t.co/m8jVlNuKjH
We have been developing polymers that can absorb multiple colours (energy) of light at once, and move / transform it to a specific point. But what are we going to do with it? We need a solar power manufacturer to take it further. https://t.co/TR3Aqcrp4y
Over a decade ago AkzoNobel/BASF collaborated to launch Herbol-Symbiotec. Herbol is one of the oldest German brands out there for professional coatings. This new paint boasted 'nanotechnology' to protect your home. https://t.co/pmXiIlStKa
The promise was 'self cleaning' paint. Self cleaning is a great idea - dirt resistant (or dirt repellent). And there are two ways you can go about this - however they are completely different https://t.co/vRrowm4ghO
Have you ever walked through a forest, looked at the leaves on the trees and thought 'why is that so clean and sparkly'? Some trees are more sparkly than others. The Lotus Leaf is particularly sparkly https://t.co/6Fo3nlYkSp
Materials Scientists may have heard of the 'lotus leaf' effect. It is a special property of these leaves that they 'repel water'. They are hydrophobic. Water cannot settle on them, it just rolls off https://t.co/c0EuP8nUmo
If you coat your material in a super hydrophobic substance, and cover it in micron sized grooves / spikes, the water will just roll away. This is a fantastic way of keeping a surface clean if you can make one https://t.co/hKgRi0ByLC
Ultra hydrophobic materials are fascinating to watch - you can literally bounce water off of them. This video from Brigham Young explains this in much more detail https://t.co/x3gIoUbO5l
However - most paints (particularly modern more environmentally conscious paints) are water based. You can't stick your hydrophobe in a water bucket - they wont get along https://t.co/Cc4LW2Zs0W
Herbol-Symbiotec was BASF and AkzoNobel's solution to this problem. They went the other way - ultra hydrophilic. They modified their paint to love water, so water would stick to it, penetrate it and lift the dirt out https://t.co/0zSnBkHQj5
They incorporated silica nanoparticles into their paint. However they needed to alter the polymers (most of the paint is polymers) so that they could distribute the nanoparticles throughout the surface when the paint dried https://t.co/ZRfFhx9Yjx
I remember going to meetings to discuss what Herbol had done and discuss whether we could launch our own competitor product. We dissected this great nano-tech innovation and marvelled at what they had done. You cannot just stick silica into your paint and expect it to mix https://t.co/xJdZARkFFA
If you just add silica to your solution the polymer can cross link it, they stick together and you end up with something that looks like a brick. You need good polymers if you want to make composite materials https://t.co/EIIsHqC4H8
Fortunately there were academic experts on this topic. People the company could turn to and ask 'we have a problem - do you have a solution?' And yes, the answers were out there. Beautiful silica/composite particles do exist. You just need to be smart about how to make them https://t.co/BV0VWfVEfI
This was my first exposure to 'real' research. Back then I was on the other side, looking over from the company perspective, egging the academic work on because it was beautiful, but all too aware we needed to make a product out of this. Long story short - we didn't
And so I left to pursue a PhD, learnt all about polymers (the thing that was causing us so much trouble) fell in love with the science and I'm still here. https://t.co/xMGFUOSCaf
And I learnt that - if you want a 'clean' surface - you need something that either loves water, or hates water. Either will do, it's things that sit on the fence that get covered in muck https://t.co/ScrClRZJJH
By the way, if anyone wants to know, these beautiful pictures are by Jennifer Balmer from 2008. It's not open access however: https://t.co/Ckql0muRY4 https://t.co/5tbkfwD8eN
It's getting a little late here and putting family to sleep has occupied the last 3 hours so will leave you with the thought that polymer chemists and industry 'both' know about the ecological issues facing our world. That's my plan to address tomorrow.
[admin] "Using & Abusing Smart Polymers" Thomas Swift (@Swifthom ) goes into the detail on the podcast #44 https://t.co/6euBRPoAgg
RT @realscientists: [admin] "Using & Abusing Smart Polymers" @RealSci_Nano curator, Thomas Swift (@Swifthom ) goes into the detail on the…
A delayed start this morning completing some teaching jobs but I am here today to talk about how our use of polymers is changing the planet, and what we can / could / may do about it
We, as a society, can do better with our use of plastics. The same chemical properties that make them fascinating also make them a long term danger for our ecosystems. We have ignored the chemistry at our peril and I'd like to extrapolate on this today https://t.co/ZMEhU8Fhah
To explain how important this is allow me to introduce my baby girl, only just over a month old now. And allow me to introduce the hedge outside my house. I have to go out pretty much weekly to collect plastic bottles / crisp packets people have deposited for us. https://t.co/3uCplNEPLD
But what if we just left the rubbish under the hedge to rot? Out of sight out of mind. What if someone had dumped all their rubbish there the night Evelyn was born, walked away, and it was just abandoned? https://t.co/VDmReY72Kt
If someone dumped tissues and toilet paper - high commodity items right now. Possibly because they do not hang around very long. Any tissues left under our hedge when Evelyn was born would already have disintegrated. https://t.co/0TiuwReWCB
Occasionally we spot a banana skin. Well our imaginary abandoned banana will not rot until she is maybe two years old... By then Evelyn should be walking and maybe talking? https://t.co/yB2F3PdrCW
What about the abandoned cigarette butts? They will take nearly a decade to rot away. So nearly an entire childhood can pass in the time it takes for these to disappear. https://t.co/5yBzLSY9ok
The cigarette buts take almost no time at all to degrade compared to crisp packets however. These bad boys will hang around for decades, lets assume approximately 80 years. That is a lot of pollution for a snack. https://t.co/vx3Xugtn3n
But the plastic bottles and shopping bags? How long will they hang around for? How old will a newborn baby girl be before the waste dropped today finally rots away? Well... She wouldn't be with us any more. Her great grandchildren will probably be old before the plastic goes https://t.co/qZF3buOMwq
And THIS is why plastic is different. It is special. It is why we should understand the polymer chemistry that drives it. Plastic is not bad, it is not evil, it has a very useful function and a purpose. However if we want to avoid further long term damage we need to understand it https://t.co/jKyxXMhGXE
Rotting is nature's way of breaking old, dead, matter down and converting it into useful chemicals. Enzymes, bacteria, fungi all work together breaking the world down back to its raw components. https://t.co/s4ZEetGsO8
These enzymes convert small molecules into other, useful, materials. However polymers are not like small molecules, they are long chains of molecules, strings of them stuck together. If you can't break the chain you can't process them. https://t.co/rGdt9FVozl
To the average punter 'Plastic' is 'Plastic'. However, chemically, there are MANY different types of plastic and they are all completely different. Most plastics are full of carbon, making them really strong and really difficult to break. https://t.co/Ifao1lhmJi
So if you want to break down a polymer you need to cut the string apart. Breaking polymers is not a one step process, it is several steps, and it is a very, very slow process https://t.co/CV11CIgQrM
Tomorrow I am going to talk about 'chain length' but the important thing for now is - these long chains are very strong. If your material is wrapped up with this 'molecular rope' it's not going to go anywhere fast https://t.co/DP1UoSQp6t
Our problem, right now, is so many of our plastics are dependent on materials full of these unbreakable Carbon - Carbon bonds. If we can move away from them there is hope. And scientists and engineers are doing this. We have plans... But it will take time https://t.co/th4WxwEp4t
And Nature is ahead of us here. Biology is full of polymers, these long molecules. Look at their structure and you see oxygen, plenty of oxygen, right the way through the chains. This chain can be broken and processed at will! https://t.co/rSVxm13FJw
Lets discuss the lifecycle of a conventional plastic bottle. It is made of plastic that comes from oil. It is refined, moulded, used, and then disposed of. We 'hope' it is recycled, and if not we would prefer it was incinerated to make energy. https://t.co/1l5krcdFG9
So, most the plastic we use comes from the ground. It used to be a plentiful resource but... I don't really want to get into the whole #ExtinctionRebellion politics except to say look at the science - they are not wrong to be concerned https://t.co/P8LUb8a51q
We are moving towards natural sources of plastics. If we can make them from starch, natural rubber, plant oils, we should get around this problem right? https://t.co/YlNmjnkhiI
Plastics degrade in 3 steps. They erode, then break up, then get consumed by bacteria and fungi. We need to make more bio based plastics which go through this process quicker? https://t.co/Sx7h9M71T0
This graph shows the direction of travel. Avoid the bottom left plastics, move towards the top right. If every company makes small, incremental changes, we could get there in 10 to 30 years, maybe? https://t.co/HH7HNWPRhf
That's all we need to do to save the planet? Sorry... I wish it was. It's a good, important step, but the chemistry is still a problem. And I'll explain why as soon as I've had some lunch https://t.co/ANsDabpi95
I'll just pop this statement from the UN. It's the ultimate problem with everything I said earlier about degradable plastics https://t.co/X5WOjc5nXp
As we got better at understanding the need for 'degradable' plastics, we got more confused about what 'degradable' means. Do you understand the difference between biodegradable and compostable? https://t.co/2u0ToiwJkh
Unless your plastic breaks down in a year or two to components that can be taken up by plants it is not compostable. Do we have good, reliable, compostable plastics? Some companies claim we do but the scientific jury is still out https://t.co/ZxI2gkJqvO
But compostable does not mean it will break down in water. Compostable means heat/ fungi / mould will kill the plastic. But most of our abandoned plastic gets into the water stream and makes its way out to the open ocean https://t.co/0ojUtqTjWr
If we want degradable plastics we need ones that break down in water. But nobody wants to buy a water bottle that dissolves in water. https://t.co/08Uk3DLFEs
Is recycling our plastics the answer? We have produced over 6 billion tonnes of plastic waste in the last century. This 'could' be a fantastic resource if we can recycle it rather than dumping it all in landfill https://t.co/NNj1iELu6Z
The people I know who work on plastic recycling HATE degradable plastics. If they get into their products it would case all sorts of problems for them. You cannot recycle something designed to self destruct https://t.co/kaBMKZ1xN7
However, whilst the polymer chains are 'strong' they are not invincible. Recyclers need to be careful not to damage the chains. It may be difficult to recycle these things forever https://t.co/9Yb17rhWCZ
Mass recycling of plastics means separating the 'type' of plastic. I am aware of 7 common recycling streams that are widely used (at least in the UK?). There are far more than 7 types of plastic https://t.co/1BuxP2DP92
And these 7 common streams... They aren't the bio based plastics I was praising earlier. So we have a problem - do we want to recycle or do we want to reduce fossil fuel consumption? It's going to be difficult to do both https://t.co/jIvc86spLf
Recyclers tend to re-enforce their products with 20-30% 'fresh' polymer material. This means recycled products are good - but we are still some way off what we would call a 'circular economy' https://t.co/gLSKjnwvCv
Everything I'm saying today is kind of based around this problem - everybody loves plastics, few people 'understand' plastics, now everybody hates plastics but our world depends on plastics. Plastics themselves are not evil. https://t.co/EhPdWe27HI
If we could recycle 99% of our plastics, and any new feedstock came from bio based sources, we would be in a much more sustainable position. Brilliant scientists and engineers around the world are working on this. https://t.co/ElVDexZyZe
But our problems are still not sorted. I'm going to take a break but we 'still' have a problem that I want to flag up when I get back https://t.co/KZaO8BRfmP
@Haris92 This graph from the nova institute shows the roll out quite well - however it is still less than 2% of all plastics. This is going to have to increase a lot if change is going to occur which requires big industrial shifts https://t.co/7Xhpmu00Sq
I'll try to put some examples up this evening https://t.co/h8smL2UdtM
@1Gy_too_many Let me put a pin in that - I WILL 100% respond this evening. You are 2 steps ahead of me. But quick answer - I think it's interesting
So... I now feel old because I 'worked through' the microbead cosmetics scandal. This was (and still is) extremely hot news a few years ago because it was such a good example of people not thinking through the consequences https://t.co/XaVHGMr2E4
Seriously. Four years ago I'd go to colleges and schools and this would get them all sitting up, checking their cosmetics purses. Now I get blank expressions and '2016? Yeah, ancient history man' https://t.co/gWMoUSWVYC
But it may be the worlds best 'consumer revolt' of the last decade? People stood up, pointed at what was happening and loudly declared with one voice 'this is wrong'. Well done people! However, perhaps the angry mob put their pitchforks away too early... https://t.co/Cw1ffbiLYy
What do I mean 'microbead scandal?' Well, cosmetics firms started putting these little plastic beads in their products. They were hard, and 'exfoliated' your skin when you rubbed them over your face. They gave their products an 'ooh, I can feel it working, that's refreshing' feel https://t.co/xgzLOczGTy
This happened 'around' the same time scientists started spotting plastic flakes in the oceans. Tiny beads of plastic that float around and get everywhere. Birds and fish were eating it, it gets into their stomach, and then we eat them and it enters the food chain. https://t.co/DchambROTb
Back in the day I went to conferences where we debated the 'definition' of a microplastic. I am still deeply unhappy where we ended up. The definition, as it stands, is roughly 'Any polymer under 5 mm in length' https://t.co/BmkbwKgQVE
I'll explain my grievance in a minute but clearly something had to be done. Cosmetics are a luxury item - there is no NEED for the plastic to be there. We had a problem, we had someone to blame, legislation was 'relatively' swift https://t.co/WGUwHtDdKD
Here's a cute Youtube video that might explain this in more detail. I think it shows the problem really well - microbeads were seen going down the drain and into the oceans. We've come a long way https://t.co/Lz9qvcAM2L
Microbeads are now 'mostly' banned. Problem sorted? I'm afraid our oceans are still being filled with microplastics. They are not going anywhere soon. https://t.co/D508FRRI69
A lot of people, have done a lot of soul searching, and... There were probably always 'some' microplastics even before microbeads. Microbeads were awful, and brought the problem to public attention. 4 years ago we had a handy villain but microplastics are still a problem https://t.co/wZ9z62vMz0
So... Who else, like me, gets fed up of replacing their car tyres every few thousand miles? Have you ever wondered where the rubber's gone? It's not just evaporated. https://t.co/FU3839AjLg
Look at an old car tyre and the evidence is clear. It's been shedding tiny plastic fibres every time you brake hard. Some experts think, maybe, 28% of all microplastic comes from these bad boys. But nobody is suggesting we ban cars... At least, not for this reason https://t.co/bqEzuQrKE2
And is your tennis ball naturally sourced? A lot of the 'fur' on a fresh tennis ball brings are plastic fibres and it sheds them as you use it. Microplastics EVERYWHERE! https://t.co/LMPq6TfWwQ
And consult your teabag manufacturer to ask if they use a polymer wrapping? If so it will be shedding plastic fibres straight into your stomach https://t.co/x6sB9eQQc2
In fact every time you do the laundry... Microplastic fibres. All of them dumped down the drain and out into the ocean where it wont degrade. We are only now understanding what a massive issue this really is. https://t.co/KfzSKwkrd7
Just banning things will not get us out of this. We need better solutions. Even if we recycle 99% of all plastics we will still have microplastics. Even if we make everything 'compostable' they will still get into the oceans. We need new solutions. https://t.co/NvriVeYJ0p
So the question is - should we just stop using plastics? The wider public has definitely turned against 'single use' plastics but they are still thinking 'macro'. The problem is chemical. The problem is that -C-C- bond. And we definitely should NOT abandon plastics as a concept https://t.co/BZpF4iivmd
"Plastics are often used in products that help to reduce much larger amounts of greenhouse gas emissions over their life cycle." - Moving to lightweight, high strength, plastic composites has vastly reduced how much carbon we emit. https://t.co/hqHIQkg9Tq
“Plastics are lightweight and strong – without them transport costs and emissions would skyrocket” - without plastics we would consume more fuel moving things around the world. https://t.co/ZkXptWB4Lk
“Putting food in airtight plastic containers can increase its shelf life and reduce food waste” - It's an international scandal how much food we waste. And without airtight plastic packaging? You bet the problem would be worse. https://t.co/R7QgwHrlKF
So... Uh.... Where does that leave us? https://t.co/Er4B5p29Eh
But the situation is not hopeless. Again, there are people thinking about this. Long term solutions are unclear but scientists, politicians, engineers, manufacturers and retailers ALL need to get together to sort this out. https://t.co/T4G4MzXv4A
Enough with the generic doom and gloom. I want to present some hard facts. My favourite study from 2018 was a paper about turtles. Everybody likes turtles. The full paper is here but not open access: https://t.co/DI7gxk4iIg https://t.co/kxJPakAdCK
We eat a lot of fish. And the trawlers pick up a lot of other creatures besides the fish they were aiming more - sadly this includes turtles. A study was carried out on some Hawaiian 'bycatch' turtles to ensure their deaths was not in vain https://t.co/bK9vxx52PN
They studied turtles in this region in the north pacific ocean. They found 3 different types of turtles, and in the stomachs of each of those turtles they found >10 different 'types' of microplastic https://t.co/8b4lsw10V9
In those three types of turtles the composition of ingested plastic was different depending on whether the turtles scavenge off the ocean floor, or whether they tend to swim nearer the surface. https://t.co/yicmOr4WAR
There is so much more to this but I applaud researchers who know their stuff. I go to talk to marine biologists / geologists / (?generic water scientists?) and they don't all understand what a polymer is. Because its complex and not their field. https://t.co/swYsr0eHpT
A marine biologist may not appreciate how many different types of plastic they are, or about the importance of chain length or architecture (potentially tomorrow's topic), or any of the things I spent Monday spelling out. This is hard stuff to learn https://t.co/3sJNXq2PXG
But yeah, we need the data, we need to know EXACTLY which polymers are worse for the environment so we can focus change where it is needed. Without their help we don't know what damage we are doing https://t.co/PoYEkTt0aO
You cannot just shout at a company that it is evil and should stop. It wont help. You need to suggest small things they can do to improve. Point out the little things, relentlessly, force small changes and they will walk a path to self improvement. They want to improve. https://t.co/Hhr4ZgUmaG
Anyway, that's my plea for everyone to come back tomorrow when I talk about the tools polymer chemists like me use to analyse our materials. The rest of the chemists think we're weird. And I'll be back after dinner to actually give some positive vibes - we are NOT DOOMED https://t.co/ltEGZN6c0R
Okay, I've set out the problem as I see it. There is much happening to improve the polymer science of plastics. Here's what 'we' (as a planet) are doing about it. https://t.co/yOcU074ylo
There are funding calls for engineers to develop robots that will trawl our oceans, gathering plastic for recycling. The plastic (big and little) could be scooped up and brought back to land https://t.co/X0TcN1jMnw
There is a LOT of plastic in the ocean, potentially a valuable resource for generations to come if we can get the chemistry right. As they used to say 'there's gold in them thar hills' (if by gold you mean plastic rubbish and hills you mean the entire ocean) https://t.co/9X11svr3as
And even if we can't recycle it at least this would bring the problem back on land where we can deal with it the normal ways
I think it's a great idea. Any cleavage you can do will shorten the chain length and speed of degradation. I'd love to know if the process was energy efficient but in principle it is exactly what we should be doing https://t.co/aLCvG7IpBi
As I said earlier - breaking down polymers is a multi step process. Cleave the chains, make it more accessible for attack. However it will work for some polymers better than others https://t.co/430pGiqEDa
However @1Gy_too_many PLA (one of THE big 3D printing materials) is one of those polymers that is considered 'degradable' - see all that oxygen. It will break down on land but very, very slowly in water. If you can speed that up is great - but wont work for some other polymers https://t.co/m4trvadSjt
And I'm back to the need to determine the 'type' of plastic you are dealing with. Recycling plants have almost automated this for finding the 'types' that work. IR sensors pick and choose what they can recycle and eject anything they can't. The process is hypnotic to watch https://t.co/3rXgjjUx7J
But we can go even better. Let's go left field. What if our plastic was even stronger? What if it didn't break, or age, or fragment? What if it could repair itself back to full health when it got damaged? No more microplastics! https://t.co/FYqEBVGulv
Here's a technical demonstration from another group taken almost a decade ago. It is a fascinating prototype - a hook that can heal itself when cut. Self healing polymers are fascinating materials https://t.co/xgydyqz91b
Here's one of our prototypes - if we can make them self heal we can also make them more resiliant. This is the same elastic product that we added a healing factor to and it can now stretch to 7x it's original length before breaking. https://t.co/mJuNWh86hV
The group in India we did this work with were brilliant. Their concept was to mix together two oppositely charged copolymers to form 'attractive micelles' that stuck to each other. The two components do nothing on their own but together become 'regenerative additives' https://t.co/7w38WvtjgQ
It may seem odd to advocate that 'the problem with polymers is they are nearly indestructible' and then say 'well one solution is to make them ACTUALLY indestructible' - but again the goal is to cut down on waste. These will be great for high value applications https://t.co/MlgG0XN29w
@1Gy_too_many Even a small amount of chain cission will help. I just expect it won't take much energy to fully break down PLA whereas it could take a lot more to break down PET. The question would be where you draw the line for resource management
Have dug out some photos of the FESEM (top) and TEM (Bottom) of the individual components (left and right) and the joint aggregate they form when mixed together. Ionic binding is a powerful driver. https://t.co/0soqmkNtj6
@1Gy_too_many Thankyou, is much appreciated.
And a photo of me visiting our collaborators in India to celebrate after the paper was published. We made and characterised the polymers in the UK but most the materials testing needed their expertise. Different laboratories have different strengths - we can exploit that https://t.co/vwyLVCXu6h
A few final things I meant to add earlier but ran out of time. We can re-enforce our polymers to stop them fragmenting and producing microplastics. We can gather and recycle them from the oceans. We had a suggestion to use radiation to break them down
The alternative is to engineer new enzymes that 'can' break down polymers. I've spoken to quite a few biochemists interested in this - progress is being made https://t.co/k6DGPgFG2z
However whether we 'want' a material that can cleave carbon bonds? Imagine a grey goo that can burn through carbon or diamond? Is it something we'd really want to launch on the world (photo credit https://t.co/zT9yvK4yiR) https://t.co/BBLdsOXpah
@Haris92 Sugar is the main source of a lot of biopolymers, although there are other sources. One of the concerns out there is we shouldn't encourage competition between feeding people and making plastic. But rolled out properly its a very exciting area https://t.co/0vvsJLnD2J
So, despite all the dangers flagged this morning, every aspect is being studied by 'someone'. The world has taken note of the dangers of rampant plastics - however don't expect things to turn around tomorrow. https://t.co/VosVmJwtsM
To roll out positive change we need two things. We need demand from consumers to force us down that route to continue. Whilst the media keeps the focus on plastic pollution that shouldn't be a problem. https://t.co/c3bEI35Q7Z
We also need rigorous, scientific testing. Some of the 'eco-plastics' proposed so far degrade into quite nasty by-products. Plastic bags are not great but they wont poison you. https://t.co/eUY1X9coXN
So tomorrow I want to talk about the specifics of testing polymers. As I alluded to with the marine biologists earlier - it isn't simple. It's past bedtime here so see you soon
And as part of that I'll explain my grievance with the arbitrary definitions of microplastics https://t.co/JI3lYm2agK
Been a busy morning but I will be back this afternoon to talk about analysis of polymers. It can be difficult, but the oddities are fun
Polymers are long chain molecules, with many repeat units. Scientists are usually very good at determining 'what' a chemical is but they are not quite at adept at determining how big something could be https://t.co/3VxUpcoSFe
The best 'size' method for the standard chemist is an instrument called a Mass Spectrometer. You may have seen these at airports - they are now routinely used to test baggage for traces of explosives. https://t.co/73UfhU0PQ5
In its simplest form 'Mass Spec' works by flinging the molecules down a tube and seeing how far / fast they fly. For small molecules it is an incredibly sensitive method of detection - hence the use in mass spectrometers https://t.co/nUX17apSvg
A high end mass spectrometer can spot the extra mass of one single neutron in a molecule. This means it can be used for radiocarbon dating of fossils - determining how much C14 in the molecule remains can tell you if a dinosaur if 65 or 165 million years old https://t.co/MtLtkSCBgV
But polymers, particularly synthetic polymers have two problems. The first is they are big, and the bigger something is the less efficient they are at flying. You need a 'very' strong 'catapult' to launch these suckers. https://t.co/0NgTKQ4X4g
And the second problem comes right back down to the way we make polymers. Broad generic statement about all Polymer Chemists. We hide it well but we're just not very good at this. 🙄 https://t.co/uvYim8Nsw6
We can make polymers. We can make tonnes of them, our factories are literally churning them out. But here I need to explain 'dispersity' and bring back our molecular models from Monday https://t.co/3sJNXq2PXG
I want to talk about this paper from S. Harrison in 2018 - however it isn't open access. So bear with me whilst I lay out what it's saying for those who can't open it https://t.co/O9JbakUa4i
A polymer is a chain of repeat units. However when 'we' make long chains controlling the speed of the reaction is difficult. Synthesising long molecules takes a long time and we cannot ensure that they will 'all' be the same length https://t.co/y3sGKOdNVI
Polymer Chemists have a term 'dispersity'. It is a measure of how 'similar' the lengths of all our pieces of string are. In an ideal world, if everything was the same length, if all our molecules were 'the same' we would have a dispersity of 1. https://t.co/ziKXY5WMIp
The larger your dispersity the more variety you have in your sample. They are all the same polymer (type) but they are different lengths. And trying to work out if all your chains are the same length is difficult. https://t.co/fmgMosfq5M
In traditional polymer chemistry our dispersity values would be huge - over the last 3 decades we have developed techniques bringing them down to 1.1 - 1.3 ish when we need to…. https://t.co/wwTNg5BqLv
But, as Dr Harrison pointed out, if we applied the maths polymer chemists use to people's height... Well, this is the 4 members of family. They have an average height of 122 cm and a dispersity of 1.18. https://t.co/rhG64JRBMd
Let that sink in. Even with a dispersity of 1.18 they had a baby (50 cm) and two fully grown adults (over 5 feet tall). Polymers are, a little like this. We, as chemists, just can't make them all the same size. https://t.co/qc6lKUrGBi
His sample size is small but I would also point to the fact no member of the family is 122 cm tall. They have two tall people (adults) and two small people (children). This is a bimodal distribution and polymer chemistry is FULL of bimodal distributions https://t.co/toeKuH2eno
Got annoyed last year when we bought some polymers with a stated mass of 100,000. When we tested them I don't think there was a single chain that long in the bottle. Half were approx. 50,000 and half were approx. 200,000. The dispersity was reasonable though so same difference? https://t.co/yA94QiKhwG
Heh. I got really caught out the first time I saw one of these in an airport. Apparently if you spend your time in the security que leaning over and staring with intent interest at their machines, trying to work out what analytical kit they have, they take quite a bit of offence https://t.co/pvDWGtF1Ei
So - if flinging our polymers is not a good way to measure their size? What's the alternative. Well, we do have a gold standard within the polymer community and it works a little like Poohsticks https://t.co/i6w3hDD2gM
Has anyone played Poohsticks? Am I alone in this? It's a great game if you have a stick, flowing water and a bridge. https://t.co/poHGc5DPL0
However unlike sticks Polymers running down a column are very predictable. The bigger chains will get trapped and slowed down whilst the smaller ones will slip through unimpeded https://t.co/WQnUjIgWxt
Running a lab knowing you 'need' very specialist kit just to know how big your polymers are is stressful. Purchasing these is expensive and they break easily - especially if you let the liquid run out #numberonelabsin https://t.co/PhXqQSvAKU
However watching the robotic arm inside inject fresh samples is hypnotic to watch. As our laboratories are shut I can only show you this video I recorded last year https://t.co/LQCHHNJiBt
So the larger polymer chains come out first and the smaller ones follow. And if you'd like to know why I get so hung up about dispersity its because I deal with polymers that are a little like this. We HAVE to be accurate to tell them apart https://t.co/hEAYma5iv4
So exactly how do I end up with such awful materials? They aren't awful - they are beautiful - just a little more complex than your average chain https://t.co/VsZoPTlEjW
RT @polybiomat: Read the full study on our work on developing polymer characterisation techniques for difficult polymer systems here https:…
Imagine my laptop charing cable is a polymer... (well it is half made of them). Here is a long chain, just floating there. Occupies a lot of space for not much mass (length) https://t.co/MmK3cSSxSQ
If I add a branch (shown here by me tying it in a knot) it appears much smaller. It hasn't changed in mass (length) just volume. This is where polymers get VERY weird https://t.co/lm5ylrHGtA
Like the dense foliage in trees, branching allows polymers to get really, really masive without filling much more space. And when we analyse them down the column we are measuring size not mass https://t.co/kF4DBPCuW7
I kind of wish how big we were had almost no impact on how much we weigh but we are where we are. Branched polymers can weigh a lot but come in pretty small packages https://t.co/3dqgYPDo4h
And there are different types of branching. Dendrimers are the 'ultimate' form of branching - polymers that split, and split, and split again forming a massive brush from a small and empty core https://t.co/P006vFafBg
So - the 'horrible' polymers I showed above? We think they look a little like this. Long chains branching criss crossing around a core. These polymers are incredibly complex, and incredibly branched, and as I'll talk about tomorrow incredibly useful https://t.co/fmli4LeH8h
I just haven't been able to post what I wanted today for multiple reasons - best thing to do is probably have a good nights sleep and get back to you tomorrow to continue the planned content.
Am back for Friday Materials Science. I want to tie back what we missed from yesterday (polymer characterisation) in with our work on infection diagnostics
I am particularly interested in what I call 'smart' polymer chains - these are materials that respond to their environment by swelling / collapsing. They can respond to temperature, pH, salts. https://t.co/zpZXvx1jBS
When our polymers collapse they tend to group up. The 'accumulated mass' of polymers piling on top of each other means they form into particles that we can analyse fairly easily with scientific instruments. https://t.co/nWCbZKPGMT
Here is an atomic force microscope image of some of these distorted globules. These are linear polymer chains (polyacrylic acid and polyacrylamide) that have just collapsed in on themselves because the pH is low. The individual chains are only a few nm across https://t.co/P4B3t2wWES
Here is the same sample, if we raise the pH, shows the globules just fading away as the individual polymer chains escape back into the solution. The AFM has picked up just noise - just flakes of noise https://t.co/yzR0XVWuzW
And here is exactly the same sample under an optical microscope - we are able to form polymer particles that form and then dissolve with just a 0.1 change in pH https://t.co/ngLG7Mpekr
This is a great example of what we call polymer complexation - amorphous materials associating / dissociating with each other in solution. As Materials Scientists we are 'very' good at studying the collapsed particles but the stretched chains - more difficult https://t.co/D1j9jZQes4
It's very difficult to study dissolved polymer chains as they just wont keep still. We have some brilliant techniques however that I want to pull out and show off after my next meeting https://t.co/qlCWhro1ve
Yes, a lot of people 'describe' polymer association across the chains as a ladder effect - they are looking at DNA and thinking of each link as a rung on the ladder. It's a lovely model but for most polymers the evidence does not bear it out at all https://t.co/wiZgOzca97 https://t.co/Oidh82B6HS
So - my go to technique for studying the movement of single polymer chains in solution? Tag them with fluorescence dyes and use light to track their movement https://t.co/FIHUjFRQRh
Dyes are great molecules. Some of them are inorganic (metals) - you can get a lot of different and bright colours by mixing metals together. However mixing metals / polymers is a 'whole' other conversation. Things get sticky https://t.co/ZCbU722tLH
So I stick to using organic dyes - like this one. See the double bonds (dashed lines) between the carbon atoms. It means it can absorb light and re-emit. It's a fluorescent dye and it's awesome https://t.co/7ghTxHpmzJ
You can drop your dye into a solution of polymers to see if they interact - the dyes have a lot of carbons so they tend to seek out our polymers and stick to them. We'd call this 'hydrophobic association' https://t.co/QkryohkOXs
But you get the most out of them by covalently attaching your dyes so they stick directly onto the polymer chain. Here is our acenapthylene molecule sitting in the middle of a polymer chain, minding it's own business. One outlier amongst a sea of acrylic acid units https://t.co/FRclp3z4X5
The polymer doesn't know it but that 1 tiny acenapthylene unit is our eyes and ears onto what the polymer is doing. We've successfully incorporated a spy into the backbone that can report on everything the polymer does https://t.co/tAjsLA4Ecp
So, when the polymer coils, stretches, collapses, binds, or does whatever it fancies, our spy dye sits unobtrusively in the centre. All I have to do is shine light on them and the fluorescence spectra (and lifetime) will report back) https://t.co/owdkLLEQFP
We have a device that can count the photons in, then time how long they take to come out. If the dye is 'crowded' (i.e. in a collapsed polymer) it may take longer than if the polymer is swelled. Why does this happen? https://t.co/taOMAKLOHv
We 'think' this is because the solvent molecules can collide with the dyes. Every molecule is moving quickly with Brownian motion - and could knock the light out of our dyes. If the polymer collapses it shields the dye, protects it, and it holds onto the light for longer https://t.co/v4xmoJ6V4S
In this scenario remember light = energy. When the dye grabs the light it enters what we call an 'excited state'. But this isn't stable - it can't maintain this super form for very long. https://t.co/reZhHcEyGs
Dear all - a throw back to yesterday - I spent a lot of time discussing why the oceans are specifically a hotspot for plastic pollution https://t.co/owX3XJJPyB
And if you polarise the light going into the dye, and stick a rotating polariser to the detector, we can see how fast the polymer is moving. Polarising filters are brilliant inventions - as people with smart sunglasses may know https://t.co/lZba7hdn4R
So - with fluorescence - we have a method to independently measure shape (coiling) and speed (mobility). Our other methods mentioned yesterday can measure size (volume). That's pretty much all we need https://t.co/D7Eq99tYcq
But the really exciting stuff comes when you have multiple dyes... And that we can bring up this afternoon https://t.co/h8RgcFhm7d
We are in the middle of a crisis in global healthcare - and I am heartened with how much people are slowly coming around to the advice regarding cleanliness. However, when this virus passes, we need to remain vigilent https://t.co/9EqUVza0N3
For the last decade I've been working with a group very concerned about antibiotic resistance. They asked what if the smart polymers described previously could bind to bacteria? What if we could use them as a sensor for infection? https://t.co/KTvVxtrrLK
We functionalised our polymers with fragments of antibiotics and - amazingly - the collapsed globules work really well at binding to the bacteria surface. They grab the bacteria and drag it out of solution https://t.co/5nSuNY3E4s https://t.co/9r7fR5Hlmd
If we add one of our reporter dyes to the polymer we can get an instant readout to the bacteria binding. The polymer will collapse and we can get a signal for the presence of bacteria in minutes (not hours) https://t.co/xY0x1BxYUt https://t.co/XWTsKagNmT
To do this we need highly branched polymers (as discussed yesterday) with fluorescent tags (as I just laid out) that have SMART properties (desolvate from water - as discussed Monday). Phew, this amalgamation of physics / biology / chemistry / materials science is awesome https://t.co/KQkcejEFrR
Imagine a world where you go to a doctor feeling ill, provide a sample and get an initial diagnosis of your illness in half an hour. Do you need antibiotics or antivirals? Is it just a cold or something worse? https://t.co/pNpje4HkRQ
RT @Swifthom: Loads of thanks to @microshep who is still collaborating with us on this, and @polybiomat where any and all future news (we h…
The extra attractive force our polymers exert (our SMART materials) mean they can actually extract bacteria from a biofilm. Biofilms are one of the main reasons antibiotics sometimes fail. This is an extraordinary level of force https://t.co/NYBSRiYhAw
When left to their own devices bacteria tend to form small colonies for protection. Even if you treat with an antibiotic these colonies can resist the infection. This is one of the contributing factors towards #antibioticresistance https://t.co/cqfRc2Sj6V
We've also used our fluorescence dyes to study how 'strong' the building blocks of the bacteria surface are at forming these biofilms. Fundamental polymer chemistry drives this biological process of bacteria growth and reproduction https://t.co/vhXFtAPkqa
All it takes is one polymer molecule to grab and stick to several bacteria. Our polymers can be targeted to only find specific strains - and they do not kill them. Most bacteria we've tested go 'dormant' on binding but do not die https://t.co/S35pF43bso
We hope that, soon, our polymer products could become part of a new age of medicine - rapid diagnostics. As we are seeing now - the problem is testing. If we don't know who is ill we cannot treat and we cannot contain. https://t.co/buuzoaWNCT
And this innovation is only possible because of our understanding of complex polymer design - linear chains do not work. If your binding site is along the chain it actively stops bacteria sticking https://t.co/zDng5a9oi0
Graphs aren't fun but they are evidence of this. Our branched polymers (in dark) are far more volatile than the linear polymers because the linear polymers are not collapsing when they see the bacteria. In this instance the Linear Polymers are not 'smart' https://t.co/iIVsJSsSRX
The more we understand these complex systems the more we can do with them. Synthetic polymers 'could' be just as functional as biological proteins if we improve our understanding of their mechanisms. https://t.co/AuhhLXntKx
Theory, testing, modelling and simulation go into designing increasingly complex polymer architectures as we work on these materials. The chemistry and physics are on the surface 'simple' but can be unexpected https://t.co/QLwmtd0MXz
And the Postdocs and PhDs of our group have run public demos showing the almost instant colour change we can see with our materials. We've sat down to speak to nurses and doctors about their need for this technology. They showed us (pre-virus) how important washing our hands is https://t.co/JhXCFrI5X7
However we may need to work on better demo's than our current fuzzy felt prototype 😅 https://t.co/mOCax0cIum
Late last year I spent a week trying to help a manufacturing company (full of smart people) understand the functional difference between polyacrylic acid and poly sodium acrylate and why their products had started gelling. That sodium alone makes a massive difference https://t.co/zlNUA85ujK
@DishPodcast - and what's the main ingredient raising the pH in your formulation? It wouldn't happen to be Sodium Hydroxide would it? The difference between not enough sodium and too much can be as low as one part per million.
Here is a 50 litre reactor (from our soap making project) with 2 ml (less than 1/10th of a shot glass) of 0.5% NaOH solution added. We screamed and cursed but the whole batch had to be scrapped. I often feel sorry for formulation chemists dealing with this everyday😆 https://t.co/Yw318uWae3
@DishPodcast Sorry - that wasn't directed at you just a generic 'this is what I find with most people who are having trouble'. 😅 Yeah, co-solvency and hydrogen bond disruption is a whole fascinating field that terrifies me for its complexity. I try to stick to the basic polymers
@DishPodcast Every scientist has their own specialist field but for me 'this' is the easy stuff https://t.co/e9pwfZz6PL
I mentioned earlier that we had multiple different fluorescent dyes to tag polymers, and that the world got exciting when they are missed? Full introduction from yesterday morning here https://t.co/aWayfW19ld
We have a toolkit of fluorescent dyes which can be rolled out for specific situations. I'll spend a minute walking you through some of my favourite examples https://t.co/daRdAZJ1uu
My go to fluorescent tag shown off this afternoon was acenaphthylene - it's a small dye and so has the least influence on the polymer chain. It sits tight to the C-C backbone and reports on molecular motion very well https://t.co/7FDhfjeuiC
ACE pairs very well with AMMA (anthryl methyl methacrylate) - it hangs a bit looser off the chain and so rotates a bit more freely doing its own thing. But it can take the light 'from' our ACE dye to make a light - relay. We call this FRET transfer https://t.co/nESqQmfjb7
Pyrene is an odd one - It emits 2 peak colours of light - and the ratio of them it emits depends on how close it can get to other pyrene molecules. In some solvents it gets up close and personal whilst others it keeps back. We have smart polymers - this is almost a smart dye https://t.co/UOqzZSXqfb
And Pyrene is a fascinating reporter as you don't 'need' to actually attach it to the polymer you are inspecting. You can, and we have, but you can also just add it loose in the solution and it will provide data about how effectively your polymer chain wraps around it. https://t.co/MLY62WCLoT
We have had great success with nile red. How red? It's colour shifts depending on the polarity of its surroundings - so as our smart polymers coil around it we can watch the colour change instantly. https://t.co/MaFVzqACgM
Most of the prior dyes are good for synthetic polymers, where we add the dye when we make them. But for biological molecules? AmNS can be clipped on without affecting the host molecule. https://t.co/ziKKflloL2
How have I still not published anything using fluorescein yet? It's 'the' go to fluorescent dye - famously a sickly green - and it can also be stuck into polymers with ease. We've made loads but despite being an easy hit we've found little use for it specifically https://t.co/a6LuwkwcjP
We have a lot of these molecular reporters, a toolkit to choose exactly what we want to find out about our soluble molecule. There are more but these are most of the ones I've used over the last decade. https://t.co/P5L2sg89B7
We need a toolkit this large because - we hope - the dye is not influencing the polymer. We want to study our polymers but we don't want to change them. The larger, more complex, the dyes the more chance they have to cause problems. https://t.co/AfyFXcG2iy
So Saturday, for my final day, will report on some hands free approaches to materials characterisation and wrap everything I've discussed this week up together.
It's my last day in the account so going to wrap up some common threads from the week. I've had a lot of fun - if anyone has any questions about polymers / plastics go ahead, have loved all the feedback so far
Thanks very much - inorganic (usually nano but not always) chemists are one of my natural go to people to work with. Glad to have entertained you - we all need a distraction at the moment https://t.co/lrz23BSvRn
The current lab closures due to coronavirus have meant we haven't moved into our brand new labs 😡 So the first thing I'll be doing when life goes back to normal is packing all of our equipment up and helping our technician and PhD students carry it over
Last time we moved labs I was the only postdoc in the group and responsible for ALL of this. Glad we have a larger team now who can work on this together. Sadly materials Scientists bring with them a lot of 'stuff' https://t.co/JZTo66sxrx
So - we had planned for some downtime this year but it's going to be longer than expected. However that is not the end of the world and once we are set up in our new facilities expect great things ahead https://t.co/bmckXIlAQr
I never came back to my problem with this definition of microplastics. Well... We have an 'upper size' (5 or 1 millimetre) but the original proposals did not have a lower one. That has been rectified but... https://t.co/JI3lYm2agK
Some of my colleagues have started talking about 'nanoplastics' - fragments of fragments of fragments of plastic floating around in the ocean - just a few polymer chains long. There were calls for tighter regulation from 'non-polymer' scientists
And there should be - but people need to understand that a lump of plastic is an item - not a material. Appreciation of the complex polymer chemistry - and the 'many' different types of plastic - make this whole area difficult to regulate.
Yesterday I discussed how fluorescence tags can give us the movement and coiling of a polymer chain - but you need another technique to get its size. These chains are just a few nm large https://t.co/aWayfW19ld
On Thursday I said that we had columns that could separate our materials by size - and for most polymers this is a great way of working our how big they are https://t.co/7gAiHTqK20
And even if there are inherent problems in the way we discuss 'size' as polymer chemists - we need a common language we can all understand and 'dispersity' is the best we have https://t.co/bihpwiPXzz
But I have been working on other, cheaper, faster methods of getting 'size' data. And I've gone back to a common technique all chemists should be familiar with. Here is our common @uobchem NMR instrument - every chemistry (and many physics labs and hospitals) labs have one https://t.co/tHSmVRAeMx
NMR = Nuclear Magnetic Resonance. We drop our sample in a tube into the centre of a very powerful magnetic coil. The machine has to be insulated several times to protect people outside - even then we don't recommend pacemakers or mobile phones go near it! https://t.co/CocPiP12FB
I said many hospitals had one? Well yes, but they don't call them NMR because patients are generally scared of the word 'nuclear'. But the technique is completely safe so they renamed them 'Magnetic Resonance Imaging' - idea is the same. Stick the patient in a giant magnetic https://t.co/u2mRSBejJC
MRI is a fantastic, non-invasive, method at looking at the chemical composition inside your body. It's safer than X-rays and gives doctors much more detail about what they are looking for. Chemists love NMR for much the same reason - although we tend not to get beautiful pictures https://t.co/3P0KKTKs6D
So - if we want to work out a molecule's size - we can watch how fast it moves. You may have heard of Brownian motion - the idea that all particles are vibrating and moving - this holds just as true for polymers https://t.co/aSOCgeeFP6
Polymers move just like any other molecule, however they are a little slower because of their size. This means using NMR to study their diffusion (speed) in solution is particularly appealing https://t.co/lCqNd4nhVx
So how does DOSY work? Well we put a magnetic pulse into the field (pointing in different direction across the tube) and then we fire a reverse pulse to bring the molecules all the way back to way they started. https://t.co/bB8eP921Io
It sounds simple but because the molecules wont keep still they won't end up pointing in a uniform direction. It is this 'abnormality' we can measure - we can catch how fast our particles are moving by how out of line they are when we've fired our second pulse https://t.co/U1iHY7iLio
Remember our 'complex' polymers from when I was talking about polymer molecular weight - here is the data from using size exclusion chromatography - a pretty messy dataset. https://t.co/KHZeUyqTsw
Well here are the same samples analysed by DOSY NMR to get the particle radii (okay so we are measuring volume not mass). But we were amazed that we could get this resolution by summing all the proton peaks together! https://t.co/QGU6gCxX09
RT @polybiomat: This dataset is in our methanol GPC paper published in the Journal of Chromatography A - https://t.co/5Nu7AlNmaL - we think…
If anyone wants to know more about DOSY this webpage (Hebrew NMR lab https://t.co/UKyEiaZrrq) have some fantastic resources on it - and all other forms of NMR. Highly recommend their stuff for some basic reading about the tecnique https://t.co/AhgaCa54Rj
So DOSY takes the NMR peaks (left image) that represent different protons and gives you diffusion (or size data) beneath them. And if you configure your instrument right it can provide some information about the size distribution! https://t.co/xlKaF41TJH
So our in house toolkit for measuring size of polymers includes the size exclusion chromatography, DOSY NMR and the fluorescence techniques + several other specialist techniques like light scattering, viscometery, membrane osmometry... but they are 'far' more specialised
I would recommend DOSY to ANY materials scientist (as long as your 'material' can dissolve in 'something' - it even works for nanoparticles if they have soluble 'coatings'). It's worth a look and really should be a standard part of any #materials toolkit.
As the twitter handle (@RealSci_Nano) implies size is kind of fundamental to anything we do. https://t.co/xoz4ij9Drn
Less than three hours before I hand this account over. It has been a fantastic week, and I've had a great time working through some of things I find most exciting about polymer chemistry
Most of the properties I've disclosed come down to the interactions between the polymers with water. The smart behaviour comes from their interaction with their surroundings. Water dominates so much of polymer science https://t.co/Y1AQEhyklB
But that interaction goes both ways - it means we can use polymers to manipulate water. From self cleaning materials, to flocculants, to moisture management in wound dressings - the fusion of chemical and materials science gives us some fantastic new technology https://t.co/gMuB1VsHEN
Smart polymers have often been silently rolled out in technologies because they are useful in so many applications. They give us responsive materials, ones that show resilience to the world around them and push back. If I've raised awareness in just a few people then job done
Of, before I go, my textbooks are all at work but I have 3 general science books at home thst I have to sing praises of before I go
This may be my favourite general science chemistry book ever. As a polymer chemist I 'generally' stick to carbon... With H, O, N, Si, S, Fe and Cu occasionally useful. This book walked me around the whole periodic table and I loved it https://t.co/ybqmHG29Xf
Can't recommend this book as a 'thriller' - if a story of research can be. It is of its time though, and if you can over look the misogeny and casual arrogance of the author gives a great insight into the mindset of those who pursue science (and their own glory) above all else https://t.co/ooYAC1ADJG
And then this relative newcomer is my current planned reading for when Working From Home gets too much. If you have any recommended general science reading do let me know - looks like we're all going to have some time on our hands https://t.co/ipKW3x7KcW
So, I'm going to retreat back to my personal account (@Swifthom) and our groups publications will always go up on @polybiomat. I also update a shared lab website if your interested https://t.co/L5CJWVAX6k - it's been great https://t.co/HBGlzYBire
And I'm looking forward to whomever is next 😁
https://t.co/hpLSsFwuvw - can't even type my own website out right 🙄
[admin] Thank you Thomas (@Swifthom ) for a wonderful week of science. 🎉 https://t.co/TzfwqNXLBP
Gregor Fuhrmann
[admin] "Nano Drug Deliveries Inspired by Nature" Please welcome this week's curator Gregor Furhmann (@FuhrmannGregor ) Gregor spoke with us about his science, listen to the podcast here - https://t.co/Q4RivDhv03
Wonderful sunny Sunday morning and I just took over the curation for @RealSci_Nano. I am head of the junior research group Biogenic Nanotherapeutics @Helmholtz_HIPS in Germany. I look forward to talk about my research in the next few days. https://t.co/jAr6IHl60o
And this is BION - a group of dedicated and very talented PhD and master students; and also a postdoc. Thanks everyone for being such a great team! https://t.co/qbiP2QkK75
What is my plan in the next days? Sunday will be and introduction to our group and our work, Monday the importance of antimicrobial research, Tuesday extracellular vesicles, Wednesday new biomimetic and biogenic strategies for drug delivery...
...Thursday and Friday how the current situation affects the way we do research, Saturday wrap-up. Hope you enjoy it!
I recommend listening to this online symposium to learn more about the latest approaches in oral drug delivery @CRS_FG_Oral https://t.co/PQyeahJbff
RT @quantschmant: I’ve been quiet recently. Sorry to my collaborators, my team and my undergrads. I’m not yet settled, so you will have t…
Our group is focused on developing biogenic and biomimetic drug delivery strategies. We try to modify drugs or encapsulate them into carriers, so that they shuttle the active principle to its site of action. Reducing accumulation in other tissue is thought to reduce side-effects. https://t.co/fjZQa3n8AU
Maybe a few introductory lines about myself first. During my PhD at ETH Zurich, I developed a non invasive assay to measure the activity of orally administered enzymes in real-time and non-invasive. https://t.co/1Tokh5zR1T
We then used this method to assess the effect of polymer functionalisation on the enzyme activity. https://t.co/abavEE9KJX Using different polymer architectures, an enhanced enzyme activity was achieved because of the polymers on their surface. More on this later this week. https://t.co/mRpaz7qMvp
Now more specifically, BION is looking into biogenic avenues. That is, drug carriers inspired by nature because we can learn to optimise synthetic delivery systems through this. Biogenic and Biomimetic Carriers as Versatile Transporters To Treat Infections https://t.co/Uc5jlYKt0V
Maybe finishing on my journey in science to the position where I am now. I did a postdoc at Imperial College London in https://t.co/DdUdWr0HVH. Wonderful experience - who can spot me on the picture? https://t.co/PXEwI3MQ2w
In Molly Stevens group, I started working with extracellular vesicles and I also met several postdoc colleagues, many of them are still my friends now. @ronachandrawati @pashucklab @thechowlab @DrTinyTaps @theSeriousLab @spicerlab (list not complete, just the names I recall now!)
My group @Helmholtz_HIPS is supported by the NanoMatFutur programme from the @BMBF_Bund. We work with #extracellularvesicles and other naturally inspired carriers to improve therapy of bacterial infections and autoimmune diseases. https://t.co/3k7T83SfLD
So today, I will focus on antimicrobial resistance and why it is important to do research in this area (not only because of corona nowadays). Our institute is the @Helmholtz_HIPS in Saarbrücken and the first research institute in Germany fully dedicated to pharmaceutical research https://t.co/2EKFQ5owg5
@Helmholtz_HIPS belongs to the Helmholtz Centre for Infection research @Helmholtz_HZI focusing on antimicrobial resistance development and therapies. Why? See the info-graphic below (copyright HZI). https://t.co/vRtTp5TDAQ
According to the WHO, antimicrobial resistance is one of the major threats to humanity. An antimicrobial resistance review (https://t.co/9dIvAvsb7R) predicted that by 2050 up to ten million deaths may occur from such infections. Very interesting read with many infographics! https://t.co/8csQenL70M
And @Helmholtz_HIPS is tightly associated with @Saar_Uni as you can see from our logo!
RT @FuhrmannGregor: Also during the Corona crisis, antimicrobial resistance needs attention - co-infections may also contribute to mortalit…
@FuhrmannGregor So, following up on this, in our institute we develop new antimicrobial strategies: from mining of natural products, to chemical synthesis and optimisation and finally formulation (which is what BION is doing). Just one recent example from @Helmholtz_HIPS https://t.co/yK1R9b6cPW
How can targeted drug delivery help to enhance the efficiency of antimicrobials? “Nanoantibiotics” https://t.co/J6MlslDFiF By delivering antibiotics more selectively to the infection site, we reduce unspecific accumulation and increase local drug concentration to treat bacteria.
Of course nanotechnology cannot overcome resistances if the mechanisms are on the molecular basis. But think of antibiotics that induce diarrhea or show kidney toxicity. If we deliver them more selectively, we reduce these side-effects
When considering targets for nanoantibiotic carriers, it is also important to know who you are fighting against: the bacterial cell wall and membrane. Challenging to overcome. Nanomaterials and molecular transporters to overcome the bacterial env... https://t.co/LDek37vXzV
Here is another interesting example for a very simple carrier system to deliver antibiotics. These liposomes carry oleic acid which by itself is also antimicrobial. https://t.co/G0ispq2mvt
Just to pull out a few examples on how nanotechnology can be useful in combating resistant bacteria and what is needed in the future.
Finally, the situation becomes even more complicated when resistant bacteria embed themselves into rigid biofilms - a very tight diffusion barrier for free antibiotics. A few persister cells survive and restart the infection: https://t.co/YODycIFzYB
Nanotechnology may again help to tackle this challenge. Enhanced design and formulation of nanoparticles for anti-biofilm drug delivery https://t.co/HWqzwbfOoR But even for nanoparticles, they sometimes stick on the biofilm surface which requires careful nanocarrier design.
@NotHF I think these are very important points to consider and I would say: it depends. As far as I know there are no studies (yet) that assess the targeting efficiency towards bacteria. You are correct that cancer targeting sometime is low.
@NotHF And also for cancer targeting, it depends on the type of cancer and the patient itself. Bertrand et al. nicely compiled data on this in ADDR https://t.co/L3MgUivcBx https://t.co/w1KkXXAKxo
A bit later today, but I get to tweet about my favourite topic #extracellularvesicles These are small, membrane-bound phospholipid vesicles that are produce by almost any living cell; present in mammals, bacteria, fungi and even archaea To start: https://t.co/EdvLmodml6
Interestingly, #extracellularvesicles are involved in many cell-to-cell communication processes. These include fundamental biology, but also potential drug delivery applications Cell-derived vesicles for drug therapy and diagnostics: Opportunities ... https://t.co/Wjl3vKsewi
If you are interested getting more involved in #extracellularvesicle research, there are many national societies such as @GSEV10 @UKEVSoc @ASEV_Austria @GEIVEX @EVItaSociety and the international @ISEV_JEV https://t.co/IVJavIfIUU https://t.co/D0mTvIsNfr
RT @peterwich: Excellent paper by @LukeConnal and collegues about a bioinspired #micelle system that mimics the function of hydrolases. Gre…
Your first step when starting new in the #extracellularvesicles field: read the MISEV2018 guidelines! These are minimal information for studies of extracellular vesicles created in a collective effort of many EV researchers https://t.co/b6ZYmSLNud
These guidelines give an overview of how to isolate and characterise your vesicles. It also gives an overview on the nomenclature because EV is not EV. https://t.co/4YrfPpvlyd
We are interested in #extracellularvesicles because they are natural conveyors of cell-cell communication, they are also derived from cells which makes them potentially less immunogenic than synthetic carriers. https://t.co/vR88wTVRzu
Here are a few examples of how we characterise extracellular vesicles - this time from no-pathogenic bacteria (that usually live in the soil). Turned out that the vesicles were low in cytotoxicity but at the same time inherently antibiotic against gram-negative bacteria. https://t.co/tLUjL73Ecw
We also showed an distinct antimicrobial activity of the vesicles against intracellular pathogens (Staphylococcus aureus). These bacteria often hide within human cells to be less recognised by our own immune system. But our vesicles find them! https://t.co/A7xFCGhFw5
Didn't really have enough time to talk about #extracellularvesicles for therapeutic applications. I see the main challenges in the field to be 1) large scale GMP-production, 2) suitable isolation and purification methods and 3) appropriate ways to load them with drugs of choice.
For 1), there are efforts ongoing. Especially mesenchymal stem cells are a suitable source for cell-derived vesicles with antiinflammatory potential Manufacturing of Human Extracellular Vesicle-Based Therapeutics for Clinical Use @MDPIOpenAccess https://t.co/FjcuB7pSej @BGiebel
2) is rather difficult because of the vast number of different vesicle subpopulations which are challenging to seperate. Various approaches are followed here. For example, we try to use flow fractionation https://t.co/nL94sSrFQ3
Finally, 3) needs physical opening of the vesicle membrane for drug loading. This works quite well for small molecule compounds, for example by electroporation or saponin treatment. Get's more difficult for larger biomacromolecules because of artifacts https://t.co/w0Bq6uTKYj
[admin] "Nano Drug Deliveries Inspired by Nature" Extended podcast is out now - https://t.co/Q4RivCZTBt
The @GSEV10 started a new journal last year - Trillium Extracellular Vesicles. I was editor-in-chief to the first issue https://t.co/Cm6dFWq76A. A highly recommended reading for those starting new in the field of #extracellularvesicles
While reading the new TEV journal you may want to contribute to this year's issue. Please do so! More information here https://t.co/ven5OuXLhO https://t.co/P5DYNydVjU
Now, even when #extracellularvesicles are characterised and loaded with their desired drug, we still need to understand other factors during their interaction with target tissue. One example would be interaction with extracellular matrices https://t.co/rqG9f9wHW5
Another property to understand would be mechanical stiffness of the vesicles as this also influences cellular interactions. https://t.co/NJAkaBHvg3
And because we may potentially interested in tuning such properties of our #extracellularvesicles, I will talk about engineering strategies and other biomimetic avenues later this week...
Although we are currently having a difficult situation, we should not forget to keep fighting against climate change! This is @Helmholtz_HIPS in summer in preparation for a big climate demonstration! https://t.co/4pnOeUyKIh
I believe Easter is the perfect time for everyone in science to take a break from emails, papers and video conferences. So, keep calm and go on annual leave at home! (I am doing the same).
My self-made mask that protects others from me #MaskeAuf It also support @Helmholtz_HIPS and @Saar_Uni as you can see! https://t.co/Y0aRDPpCsF
At the next Public Climate School week in May with lecture series on sustainability and climate (https://t.co/tmZjxA0mTG) we will also participate. I am currently preparing a lecture on micro-plastic in pharmaceutical formulations.
Interestingly, the contribution from pharmaceutical formulations is very low compared to the rest (infographic: Helmholtz; unfortunately only in German). The biggest causes for micro-plastics are automobile tyres and plastic rubbish - we all need to work on reducing this! https://t.co/kkbn8UdE0M
RT @FuhrmannGregor: Yay - finally first at something! Thanks @CRS_FG_NANO for the initiative and I look forward to see many feature article…
This is the kind of biomaterial I enjoy working with! Inspired by nature, flexible to handle and completely sustainable. https://t.co/ELVVG8CTYh
Of course, BION is also trying to stay in contact by video conferencing (well, here the students had coffee together...) Plus, we rediscovered a very practical invention termed telephone! Brilliant thing. https://t.co/POAt6nkw3Z
Today is my last day as curator for @RealSci_Nano and it has been a blast! Before I say goodbye, there are a few last thoughts I have on nanotechnology in drug delivery...
I believe nano delivery offers the possibility to personalise medicines - very nice recent review article from @rvdmnanomeds. They recommend patient stratification and better drug and carrier design to overcome challenges in cancer therapy. https://t.co/TyvFyBF7rJ
And of course if we want to develop better carriers, we also need bioinspired assay systems and in vitro models. Some of these aim at resembling what happens under physiological conditions. https://t.co/NSY8GKZhFX
I say goodbye and thanks. It was a great week with nanotechnology in drug delivery and #extracellularvesicles. Happy Easter everyone and keep safe! https://t.co/Xa4QEFjoHF
[admin] Thank you @FuhrmannGregor for a wonderful week of science! 🎉 Podcast and more - https://t.co/Q4RivDhv03
Vivian Tong
[admin] "Dancing Electrons Telling Material Stories" Please welcome this week's curator - Vivian Tong (@hexallography ) https://t.co/qi4PCVeQB9
Hi Twitter! My name is Vivian (@hexallography), I'm a Higher Research Scientist in Materials Characterisation at @NPL, and I'll be curating the @RealSci_Nano twitter account this week! https://t.co/EKOtBOVI3g
@hexallography @NPL This week I'll be talking about materials and microscopy, STEM outreach, and doing research in a non-academic setting. I'll also talk about mental health and faith: bits of my personal experiences in this, and some ideas on improving inclusion for resarchers in these areas!
@hexallography @NPL Every Monday to Friday (20-24 April), between 18:00 - 18:30 (BST), I'll be around so you can #AskMeAnything #AMA. I'll also be highlighting wise people and twitter accounts I've learnt lots from throughout the week.
Today is just introductions: a bit about me, a bit about @NPL where I work, and a bit about my research, which might explains why I like hexagons #TeamHexagonal. [1/]
@NPL My research is in materials science. I look at how microstructure ('micro-scale structure') of materials change as they break or deform. Understanding how materials break helps us to make the most of the material when making things. [2/]
@NPL Electron backscatter diffraction (#EBSD) is the main tool I use to observe the microstructure of materials. To do this, I throw electrons at a piece of material and take a photo of what comes back (a diffraction pattern). More about this on Tuesday! [3/] https://t.co/gc9tuqyS1z
I work in the Advanced Microstructure Characterisation group at @NPL, which stands for the National Physical Laboratory. NPL is a measurement science (metrology) lab in the UK. Here's a great explanation from @xkcdComic on why metrology matters: [4/] https://t.co/Rq4gDWphVZ
In my job, I get to do: - fundamental research (similar to academic research), - industrial research ("solve this expensive problem for company X"), - measurement service work ("run these tests, company Y wants the data").
Before I started this job, I was a postdoc at @ImpMaterials working with @BMatB. I didn't think I could stay in academia, but didn't know many career options for non-academic fundamental research! I'll be talking more about non-academic research work on Monday! [6/]
I do some STEM outreach to schools, youth groups, and the unsuspecting public. 'Baking with Zirconium', a comedy I did for @ScienceShowoff / @thermoflynamics, is one of my favourites, though I'm usually more awkward than funny! More about this on Wednesday! [7/] https://t.co/ZThHUyP328
People who know me in real life sometimes see me being ridiculous. I have a history of mental illness - I'm better now but remain subclinically life-incompetent. On Thursday, I'll talk about how I do research when my brain has a mind of its own! [8/]
I'm a Christian - it's a big part of my life, and affects how I do some of my job. How can researchers both fully include AND disagree with colleagues with a range of worldviews? More on Friday... I know this is a controversial topic, I'll try to be mindful of that! [9/]
Many people on twitter have taught me useful things that I'd never have learnt if it weren't for them. On Saturday, I will finish my time on this account by making a list of some twitter people I have learnt from and am grateful to! [10/10]
RT @realscientists: Hi everyone! My name's Dr Dani Rabaiotti (mostly just Dani), and I'm a postdoctoral researcher looking at the impact…
RT @iamscicomm: Hello everyone. I’m @kyledevans and I’m a maths teacher / maths entertainer / jack of all mathematical trades. Looking forw…
Morning! Today I'll be talking a bit about @NPL as an organisation, and the kinds of work I (and ~900 other scientists) do there. If you work in science/engineering, what kind of work do you do in your organisation? Would love to hear from you!
@NPL stands for National Physical Laboratory, and it is the UK's 'National Measurement Institute' (NMI). Many countries have a NMI - e.g. @NIST (US) and @NMIAustralia. NMIs do research in making precise measurements and knowing uncertainty really well.
A lot of the research is on things like standardising units and calibrating measurement tools (rulers and stuff). How does materials research fit with this? Well - manufacturing materials w reliable properties is v important for engineering industry!
You knit&sell socks for a living. Can you tell if your wool supplier ripped you off? That was the theme of an engineering outreach activity I had privilege of developing with #EngineeringEd @CCCUEducation @LASARcentre. More on that this Wednesday! https://t.co/YCEikN9sv1 https://t.co/3F3O3alDkB
Research that does useful things for UK businesses ('delivering impact') is a big priority in NPL. Huh? How does measurement science help UK businesses??? Here's one possible answer: https://t.co/DknNoGzazM
Yesterday, I mentioned 3 main types of work I get to do: 1) fundamental research 2) industrial research 3) measurement service work. If you work in sci/eng, which category(-ies) does your work fall into? Which do you prefer? https://t.co/yciMk9xBA1
Majority of fundamental research at @NPL is funded through @GOVUK "National Measurement System" (NMS). Research outputs don't have to make £££ immediately, but topics should still align to govt strategy & priorities. (https://t.co/Nu4FGFkg7O)
A similar fundamental research funding route for is the European Metrology Programme (EMPIR) @EURAMET. I've not been directly involved in EMPIR projects so far, so I don't know as much about this!
@EURAMET How about industrial research? Projects can be directly funded by businesses, or govt subsidised (e.g. 'Analysis for Innovators' scheme - https://t.co/uUNQ85xWfN) Some of these results can be published, e.g. in journal papers, but not always - it depends!
For businesses, the fact that NPL's research doesn't have to be published is a big advantage over e.g. working w/ a university, where all research needs to be publishable.
The same mentality also applies to fundamental research. There is less pressure to chase 'groundbreaking' 'new' science or 'sexy' fields. Instead, our research has more of a 'boring but important' flavour. Even sexy new science is underpinned by precise measurements!
RT @tigerinstemm: Hello! Last week @ProfRachelGaN discussed the challenges of parenting + #wfh under lockdown. This week I (@BHDrummond) wa…
RT @DJSnM: During development of the A-12 engineers learned that titanium is sensitive in ways they hadn’t imagined. https://t.co/80YQJwBtvA
Hello! How was your day? I'll be around at 6pm BST (in 15 min) if you want to #AskMeAnything! Like many non-critical workers in the UK, I've been working from home. And my work atm is both literally and figuratively propped up by the Doctor⏲️#DrWho https://t.co/z87syPq3YU
RT @the_ScienceTalk: From Electron Transfer to Production line. Meet Drew Evans (@ScienceByDRE ), Materials Scientist at the Future Indus…
RT @SkypeScientist: We're going to be talking all about insects with @LauraJoanKraft! Join us RIGHT NOW https://t.co/6LV9cPZ29g
RT @CLFaye: I absolutely hate reviewing manuscripts. I think this is because I am not very good at it, so it feels like a giant struggle. E…
RT @LizzieGadd: All set for the @INORMS_REWG webinar today on SCOPE: A five stage process for evaluating responsibly. https://t.co/ezWAmbje…
RT @LASARcentre: This is always a favourite at our #primarySTEM events we now have 2 versions. The original exploring scientific & ethics/…
RT @LASARcentre: @RealSci_Nano @CCCUEducation And it continues to be such a success helping students understand how science & other discipl…
Hi! Today I will be talking about one of my favourite microscopy techniques, electron backscatter diffraction #EBSD! I use EBSD mostly to measure properties of engineering materials, but it's also used by geologists and planetary scientists to look at rocks/meteorites.
@AlexFoden, who is completing his PhD thesis on dveloping new #EBSD techniques, has a great thread explaining what EBSD is and how it works. https://t.co/TfmITG7F1i
Today was going to be the 1st day of @RoyalMicroSoc EBSD 2020 meeting, organised by @1969bpw (Brad Wynne) and @gdk199 (Dikai Guan) @msesheffield. Now postponed to 2021. I've heard of some conferences held virtually - if you've been at one, how did it go? https://t.co/UWsFqQzsPe
Fundamentally, EBSD measures the crystal structure of the material you're looking at. What's 'crystal structure'? Crystal structure describes how atoms in many materials stack together symmetrically, like the fruits here: https://t.co/dvAIgtimzr
Most ceramics & metals are poly-crystalline - their microstructure consists of tiny crystals stuck together. @Pham_Material led some cool work that flips this concept inside out - used 3D printing to make macroscopic 'meta-crystals'. https://t.co/bN1Y58azL9
Why do we care about crystal structure? One reason is: material properties change with crystal orientation. For the hexagonal crystal structure here - the material's strength differs depending on which direction (red/blue arrows) I push. https://t.co/jDhg21QreX
RT @MySci_PK: Crystal Structure (materials scientists use this term very often) But what does it mean? 👇 https://t.co/EyHsCczOEc
Q: Why do we care about crystal structure? A2: The size of the crystals in a material (grain size) affects its strength. Usually, small grains -> strong material. Sometimes, interfaces weaken the material! That's why turbine blades in jet engines are made of single crystals.
Kathleen Lonsdale pioneered this field - she did the maths to describes crystal structures (which underpins not just EBSD, but all other diffraction techniques using electrons, X-rays, & neutrons). @paulcoxon has a thread about here: https://t.co/3Eiuo2FUQj
RT @Ri_Science: One our absolute favourite books in our archive: Kathleen Lonsdale's handwritten crystallography textbook. #booksMW #WomenM…
RT @AuroxLtd: If you missed any of the sessions of our fantastic online conference last week, the links to the recordings can be found here…
@DocParmenter @AuroxLtd wow! I've just had a look, >1000 attendees! I imagine more people were able to join online than in person? Also nice to have recordings on youtube for people who couldn't make it at the time. Was there Q&A at the end of talks? How did it work?
RT @DocParmenter: @RealSci_Nano @RoyalMicroSoc @1969bpw @gdk199 @msesheffield I was at the virtual conference organised by @AuroxLtd on 7&8…
RT @RoseGWhite: @DocParmenter @RealSci_Nano @RoyalMicroSoc @1969bpw @gdk199 @msesheffield @AuroxLtd Ditto, talks were good, presentations w…
@RoseGWhite @DocParmenter @AuroxLtd ah yes - big time difference! Did a virtual conference enable you to participate, or would you have travelled to attend in person anyway?
RT @DocParmenter: @RealSci_Nano @AuroxLtd Yes, there was a Q&A, questions submitted by the audience to a side bar and then moderated by the…
RT @Astbury_BSL: Next up in todays votes we have contestant 9 (GroEL @ 3.5 Angstrom nom noms) vs 12 ( Tomato soup & focaccia). Some seriou…
RT @sarahrgauci: If you're trying to navigate #phdlife during #coronavirus make sure you give this a read 👇 @DrShaneRRR https://t.co/3elcp…
RT @DrShaneRRR: Here is a piece I wrote for all you PhD students trying to work during the Pandemic. Spread widely people. https://t.co/b…
RT @iamscicomm: Who was the teacher that really inspired you or pushed you in the right direction? I had a teacher called Pete who gave up…
RT @Maurice_Y_Lee: I've a few questions for microscopy Twitter! Why does a jellyfish need to glow? How did GFP help that jellyfish survive?…
RT @NESTA_US: #ChallengeAccepted Superposition & cross cutting relationships Can you label the order of geologic events, & type of petrolo…
RT @vancew: Liquid crystals day 8: droplets of a cholesteric LC in glycerol. I spent many hours of my Ph.D. starting at these types of imag…
RT @x_ackers_x: Hey materials science Twitter I need to check something that I would usually just ask the office but I guess you’re my off…
@rlim_photo @x_ackers_x @BMatB (are you a crystal plasticity modeller?) as far as you're concerned dislocations are matrices that tell you where you're allowed to shear and where you aren't, right? :P
RT @christineliuart: What I love most about having a science education is understanding how things work at a microscopic level! So I was…
RT @AngusJWilkinson: As we head into another day of video conferencing remember to cut yourself & others a bit of slack. "Delays on phone…
@Wikisteff @AndyWitney @mattpt55 It is amazing! They don't avoid defects in metals - you often see sub-grain boundaries in single crystal Ni superalloys. The semiconductor industry, on the other hand, can grow almost defect free Si (~1 dislocation per 100 microns square) https://t.co/ocy86rd69p
@Wikisteff @AndyWitney @mattpt55 Cosmic ray radiation limit for 10-year lifespan ? Sorry - not quite sure what you're reffering to!
RT @NatalieGCheung: While I'm not currently networking at face-to-face events, I am still keen to meet and collaborate. Book into my "Calen…
RT @NatalieGCheung: 🎙️Podcast!🎙️ @STEMLondonHub have launched our podcast where we ask @STEMAmbassadors about their amazing jobs and how t…
[admin] "Dancing Electrons Telling Material Stories" Extended conversation with Vivian Tong (@hexallography ) is out now #48 - https://t.co/qi4PCVeQB9
RT @realscientists: [admin] "Dancing Electrons Telling Material Stories" Extended conversation with @RealSci_Nano curator Vivian Tong (@h…
RT @tigerinstemm: Have you considered leaving your group/institution/workplace in the past due to a negative situation?
Hello! Today I'm going to be talking about STEM outreach things I've been part of. With much thanks to @FunSizeSuze, who encouraged me to start doing this as a PhD student! Can you think of someone who encouraged you to start a new interest/hobby?
During my PhD, specific outreach funding in a research grant (https://t.co/DRQdDMXihG) provided opportunity & resources to develop three KS2 workshops on Planes, Energy, and Bridges (led by Mitch Cuddihy, @x_ackers_x, Saira Naeem, me) https://t.co/vYwPaNA0tM
Monthly 'Imperial Lates' events (https://t.co/vTrOMW3015) and the annual 'Imperial Festival' (https://t.co/PD6aGkkJ6q) are public events, where scientists showcase their work through interactive stands and talks. (when COVID-19 lockdown isn't happening)
@SciNotSci is a podcast by @StuartGHiggins, a reminder that scientists are proper people too. This is important, as kids who like science don't usually aspire to be scientists. They also need high 'Science Capital'. Listen to @ASPIRESscience here: https://t.co/AmYk8C4bv6
RT @Wikisteff: @RealSci_Nano @AndyWitney @mattpt55 Sorry, it's some dimly-remembered work that I did a long, long time ago! The idea is th…
@Wikisteff @AndyWitney @mattpt55 ooh! I have never payed attention to materials degradation from cosmic rays before. that's really cool! Do you worry about surface effects in a finite-sized part?
RT @NatureMaterials: @StuartGHiggins reflects on his experience as both a scientist and a producer of the podcast Scientists not the Scienc…
RT @Wikisteff: @RealSci_Nano @AndyWitney @mattpt55 So the work I was on about at the time involved how large a chunk of perfect crystal cou…
RT @Wikisteff: @RealSci_Nano @AndyWitney @mattpt55 The idea was that you would build with crystals of that size or smaller, and use redunda…
Learning about science capital @ASPIRESscience made me think about what outreach I should prioritise. Turns out children already enjoy science in school! My aim should then be to help them see *science as a relevant career aspiration* by building their Science Capital. [1/]
Q: How to build science capital in children? A: Show children that scientists are proper people with multidimensional lives and come from all sorts of backgrounds E.g. @jesswade works hard to do this by writing bios for scientists from underrepresented groups on Wikipedia! [2/]
Q: How to build science capital in children? A: Prioritise regular outreach engagement over one-off events or school visits. E.g. volunteer at @sciencemuseum's @coderdojo monthly coding club. Quite a few participants are regulars!
RT @MySci_PK: @RealSci_Nano @jesswade one of our previous curators @KGoepfrich also runs an interesting initiative - @RingAScientist Kers…
Q: How to build science capital in children? A: Make science 'friendly' - relevant to life outside lessons! E.g. @professor_dave's 7yo's Minecraft Jungle Habitat https://t.co/g5E5ingI4I
RT @inyourwindow212: What a cool picture from her @TeamFoldscope slide ! Loved her response, simple but full of truth! @PrakashLab @PICKe…
RT @SkypeScientist: Fantastic Beasts and Where to Find Them: Bizarre Chondrichthyans with Jasmin Graham TODAY at 1pm! https://t.co/uZXo62…
Q: How to build science capital in children? A: Make science 'friendly' - relevant to life outside lessons! E.g. @TeamFoldscope is an inexpensive paper microscope you can use to look all kinds of things, even soap! https://t.co/uh3yVav14i
Q: How to build science capital in children? A: Make science 'friendly' - relevant to life outside lessons! E.g. Have fun at museums! @sciencemuseum trains volunteers about science capital. And @KirkaldyMuseum is small but AWESOME materials testing museum!
Why do I keep talking about science capital (@ASPIRESscience)? Because it's a framework that allows us to measure the effectiveness of STEM outreach, and compare outreach strategies. Before learning about science capital, I didn't think abt what to aim for in my outreach!
RT @zoelaughlin: @Sports_Innov8 @byeck_itshilly @Jude_Pullen We did a fake ooo workshop @of_Making a year or so ago. Air dough makes a grea…
RT @AngusJWilkinson: How have you been feeling during the covid pandemic? If you can find the time (~30mins) & strength to handle a questio…
RT @AcademicChatter: Anonymous question "My recent transition from postdoc to PI triggered an underlying anxiety to the point I had to see…
RT @xiaofei_lin: @AcademicChatter First, recognize that mental health struggle does NOT mean someone is unfit for academia. Too often, peop…
RT @xiaofei_lin: @AcademicChatter Slow down if you need it. You can't do good work until you take care of yourself. If others have unreason…
RT @tigerinstemm: Lots of stories & discussions today about leaving jobs due to unfair/negative situations, and being prepared for these sc…
RT @SaifulChemistry: For #WorldBookDay, here are a few excellent popular science books that I recommend dipping into. Includes the superb…
RT @tigerinstemm: Keeping in mind other career options or fully developing Plan Bs is a good way to be prepared for making the decision to…
RT @ZJAyres: Can't quite believe that there are ~5k of you following me, but hi folks! 👋 Thought I'd use this opportunity to update you: a…
Hi! Today's topic is about mental health. How's that relevant to research? @OptoLia says here: freedom to speak openly about mental health is one of the key contributers to a vibrant research community! https://t.co/tcDdDFEC8h
RT @realscientists: "But Dani you're an ecologist + posted all those wonderful field photos yesterday - that doesn't seem like modelling to…
Lockdown in many countries can affect many researchers' mental health @AngusJWilkinson has written a good practice guide for best practice when #WFH - inc. looking after your mental health https://t.co/DQlJN0hFYG
Poor physical & mental health reduces your available energy - often referred to as 'spoons' in the disability community. Here's @UmbralReaver's awesome explanation of spoons (& forks & knives)! https://t.co/5NRGf5Gdkz
How is spoon/cutlery theory relevant to materials/nano-science researchers? Some experiments, e.g. synchrotron beamtime, require days of experiments w disrupted sleep. It's challenging for everyone! But disabled people may be taking out knives & need more recovery time.
RT @RealSci_Nano: How is spoon/cutlery theory relevant to materials/nano-science researchers? Some experiments, e.g. synchrotron beamtime,…
RT @AngusJWilkinson: @RealSci_Nano thanks Vivian 🙏 I'd not claim it to be 'best practice' but some practical things that help me. I'd be v…
How's spoon/cutlery theory relevant to researchers? In fellowship applications! Proposals are usually written outside work time & take 100s of hrs of work. Not having spare energy affects your ability to do this, & for early career researchers, ability to stay in a job!
This disadvantages not just disabled researchers, but also e.g. those with caring responsibilities. In some ways, a carer is even less able to take on extra work that risks their health, as there are other people dependent on them being ok and functioning. https://t.co/Vq1nrzVktJ
RT @tigerinstemm: One thing it’s important to remember is that everyone’s #WorkingFromHome situation is different, so what people are able…
@tigerinstemm are a group of academics working to improve accessibility for STEMM research in the UK. They work towards improving inclusitivity in many different aspects of research work - check them out if you haven't already! https://t.co/Eol51iLpp8
RT @AnnaParadowska1: 📢New scholarship opportunities! Unique chance to have a scientific adventures at Australian 🇦🇺 prime large scale facil…
RT @DrVasshe: I’ve had twitter since September 2019. Six months later, most of the students who dm me are minoritized. They tend to either…
RT @AngusJWilkinson: In academia? Then read this thread. Let some of what it says seep in, then read it again. Be challenged by it. What a…
RT @FiDaisyG: @SSGreatBritain Many happy returns to Sir Marc Brunel, an ingenious inspiration. illustration from Brick: a world history h…
RT @SparksMaths: #lockdownmath This is a favourite visualisation of a geometric complex number question: https://t.co/4jTs5NtcUV Original…
RT @Pingosaurus: After nearly 5 months, 14 balls of wool, and quite a lot of swearing, I am delighted to say that my Persian Tiles - Easter…
RT @Cyberplasm: Would anyone be interested in a weekly biological soft matter seminar series/journal club (if one doesn't already exist)?
Hello! Today's my last day on this account, I'm going to be highlighting some people on twitter I've learnt valuable things from, both in materials/nano science and wider...
Apologies for disappearing yesterday - I ran out of energy. [Turns out interpreting pole figures (a method of plotting 3D directions on 2D paper) doesn't get easier with practice, just less impossible]
How does ethnicity affect your experience in STEM? BAME (black, asian or minority ethnic) individuals in STEM curate @MinoritySTEM each week, which is run by @HanaAyoob and @thermoflynamics
RT @jesswade: 🔬Meet A/Prof Catherine Green (@CathGreenLab), molecular biologist @HumanGeneticsOx who studies the mechanisms that underpin g…
if you're into electron microscopy, check out @nanographs! Adam has also some impressively tidy cables (sounds trivial but the backs of most microscopes are a mess! https://t.co/y3ek4vQoJw https://t.co/7PnURlx4xS
Can you teach a robot to dance? @physicsonpointe is a quantum physicist and professional ballet dancer (not a robot) who is exploring this question! https://t.co/Omt1qq7oYN
Do robots *learn* to dance in the same way as people? Could robots one day create new ideas? @LASARcentre's research explores how children learn about topics which cross from STEM into other subject areas: Art, Ethics, Theology, etc. https://t.co/Oogxs8L04L
RT @stpalli: More than 99% of marine larval fishes die within days of hatching. Why? Fluid physics at small scales! Closing the open mouths…
RT @K_Crick: Odile Crick, my grandmother, drew the first published diagram of #DNA It was 65 years ago #onthisday, as a diagram in the f…
@ADHD_Alien makes informative and helpful comics about ADHD. Not about materials science, but it is about many materials scientists - I've learnt a lot! https://t.co/4Nwk5VaMhn
RT @CatherineBroth1: @RealSci_Nano @ASPIRESscience Love your posts. A./ Yes. Most kids do love science especially at #primary school but ma…
@commaficionado tweets about life as an autistic person - I've learnt a lot through them, especially the non-public facing side of autistic people's experiences https://t.co/aeoX3S232F
I love stories, and effective scientific storytelling is a research skill I didn't know I needed for a long time! @TheRealDoctorT tells stories - sometimes about medicine, always about people https://t.co/DpknRsx37q
[admin] Thank you Vivian (@hexallography ) for an insightful week of electron microscopy, talking about mental health and science commmunication. Podcasts featuring Vivian - https://t.co/qi4PCVeQB9 Give her a follow!
Craig Bunt
[admin] "Fertilizers to Vaccines - Materials Science is Everywhere" welcome this week's curator Craig Bunt - @CraigBuntNZ https://t.co/MtWBF7jEkf
RT @RealSci_Nano: [admin] Thank you Vivian (@hexallography ) for an insightful week of electron microscopy, talking about mental health an…
Tēnā koutou katoa Ko Piripiri te māunga Ko Kura Te Au te awa Ko Te Ātiawa tōku iwi Ko Ngati Te Whiti tōku hapū Ko Waikawa tōku marae Nō Ōtautahi ahau Ko Craig tōku ingoa Nō reira, tēnā koutou, tēnā koutou, tēnā koutou katoa
Here's the translation of my introduction in Māori Greetings to you all Piripiri is my mountain Kua Te Au is my river Te Ati Awa is my tribe Te Whiti is my sub0tribe Waikawa is my meeting place I am from Christchurch My name is Craig Therefore, greetings, thrice over
I've a pharmacy degree (never registered) and a PhD in pharmaceutics, research topic was microcapsules (tiny particles about a 10th the size of a sugar grain) with cavities inside for bacteria, those 2 spheres below aren't bacteria, what I was trying didn't work 😥 #PhD https://t.co/0N2X6eSS6C
Microcapsules are a lot larger than nanocapsules of course, so I'll not say much about them. But what would be the point of chocolate nanaocapsules you'd not be able to see them with the naked eye, unlike these chocolate microcapsules I made one Easter, the lab smelled wonderful! https://t.co/S9smIztzou
About all from me today, early evening here. Tomorrow I'd like to talk about my career; how a potential pharmacist ended up researching nano @LincolnUniNZ, via VetPharma https://t.co/7BYd0isHLc, teaching pharmaceutics @AucklandUni, and a govt research institute @AgResearchNEW
Morena/Good morning! https://t.co/TyIlowtD1X
My Career; mid 80s I went to Uni to study Pharmacy, didn't do a registration year after my degree, instead stayed at Uni to do a Pharmaceutics PhD looking on microencapsulation (small particles of polymer) of bacteria (applications could be vaccines, industrial process..) then,
Got a job as a research scientist for a veterinary pharmaceutical company developing products to control the oestrous (breeding) cycle of farmed animals. Helped develop NZs first FDA registered pharmaceutical (https://t.co/TMteBZ3hzh)
Spent ~10yrs in industry, surprising published during this time (both high quality publications and patents), CV was looking strong and a lot of experience developing products for industry. Wouldn't have been possible without amazing CEO who encouraged scientists to be scientists
I learnt a lot in industry; more science skills - lots of research looking at release mechanisms (how drugs get out of a medicine so the body can use it), commercial (inventing new products), IP protection (patents). If near end of your PhD you're thinking industry, go for it!
@MySci_PK Also amazing sunsets in this part of the world; the advantage of living in the roaring 40s https://t.co/7QRZVhYkix
Yesterday was my wife's birthday and a national holiday (ANZAC day https://t.co/2MfZucXV6j). So back today to a regular day online - mix today of video teaching/group meetings. Also a short visit to campus to prepare for limited access during level 3 (https://t.co/ALCWIC4a90)
RT @MySci_PK: Talking to a new materials/nano scientist every week is such a joy. From drug delivers, fertilisers, vaccines, dancing elect…
@MySci_PK Oh dear my kiwi accent!
So yesterday I last mentioned my time in industry - while 15 yrs ago that time still informs a lot of how and what I research and teach. I try to anticipate research translation/scale-up issues, real world teaching examples, am engaged frequently as an expert witness ...
I'll rush through the rest of my career to get us to the my labs current research. After industry taught pharmaceutics @AucklandUni for 2yrs (still question why I left), then govt research institute @AgResearchNEWS for 4yrs, then in 2011 to @LincolnUniNZ ...
My last and current positions have been during a period characterized by natural disasters (https://t.co/Z8gtrRaBot & https://t.co/o7PSgktsmu), terrorists (https://t.co/2TUcRTDNl3) and a marriage breakup (not sure if this comes under natural or human disaster?) ...
Feel free to ask how I believe you can still manage to conduct, grow and sustain research while this is all happening?
NZ until yesterday was at level 4 (stay at home, could go to Drs/pharmacy, supermarket, walk round block). Today moved to level 3 (teaching remains online) but can go to lab for essential research. Don't have to give up the view from my WFH office window just yet! https://t.co/RzM71E2Plv
RT @upulie: Aotearoa you are actually too relaxed now. We aren't at Level 2. Go home.
So I have 3 yr project "Multifunctional nano-coatings for sustainable agriculture applications" funded by the NZ government. While the technology is confidential a little informaiton has been put out in press releases https://t.co/g1HzjAxSqo
It's early days yet, project started 6 months ago. We setup in Feb a site to look at in-soil biodegradation of the polymers we'll use. Nice site isn't it, on campus 10 mins walk form my office. The grass is a little brown but we were in a drought a few months ago. https://t.co/D8AZYWEIfj
3D printed samples were put on the surface and buried at 10 and 20cm. We put a fence around to keep livestock (like sheep and student) from walking all over it. Looked nice, great place to visit on a sunny day. https://t.co/6P8wGZcqsM
Didn't think rabbits leaving their calling card on the surface samples and digging up buried samples would be an issue. https://t.co/Z6rI9XXKWt
We've now caged and placed wire mesh over the samples. But it's been a month since the campus was shut, hopefully I'll have access tomorrow to the filed site and fingers crossed the rabbits haven't broken through. https://t.co/PrCGdFD8KW
I might need to get permission to take our dog Georgia on campus, as well as being able to dig for rabbits she might help with sample collecting if they're still there. https://t.co/QlrgqwGzpv
RT @the_ScienceTalk: #3 podcast - conversation with @vynisle from @polimi is out now. Michele talks about his nanoscale harmonics. http…
RT @vynisle: Thank you @the_ScienceTalk @MySci_PK and @RealSci_Nano for this nice opportunity!
Kia Ora Yesterday briefly visited campus to discuss with H&S the process for returning to the lab under level 3 (classes online, research possible). After a glass of tea (stirred with a lab spatula I purchase for dispensing classes in 1988!) I'm going to check the rabbit damage https://t.co/yxJtqExY1d
Controlled release, be it for medicine or agriculture have a lot in common. Controlled release can achieve better delivery (medicine/fertilizer...) and avoid the peaks (too much) and trough (too little) of repeated applications. But constant release might not always be best. https://t.co/AeUEelkyxk
Often we need multiple (not constant delivery) injections of vaccine (booster shots) to achieve immunity. Microcapsules (mc's) in a single injection could be designed to release doses at three different times, thereby matching better with how the immune system can best respond. https://t.co/FiaZKXg4aQ
Plant requirements for nutrients (fertilizer and such) aren't constant, once a seed is planted there's a delay waiting for germination and as the plant grows nutrient needs increase. There may be the need for an extra pulse of nutrients as the plant fruits... https://t.co/ioSqBbBMCl
Conventional fertilizer coatings like the one is this picture can't achieve this sort of control nor are they very precise. Thinking about the the challenge to make better fertilizer coatings directed us to seeking a nano technology solution https://t.co/XkeibxduMJ
RT @AlexGelle: So excited to share with you the first speakers of @pintofscienceCA online festival starting May 11th 🍺 🧪 We worked hard t…
RT @pintofscienceCA: 🎉Good news everyone! Our website is live and ready for you to check our program for Pint of Science online💻! To get…
Today I went back to campus for a longer visit, first to my field site to see if over the last 5 weeks there was any significant rabbit damage - here's a video of the drive from my hoe to the field site, sorry for the dirty windscreen https://t.co/xWixULEhrH
The rabbits have been busy outside the fence to my site! Actually didn't see any, normally I see about 10-20. I imagine they are liking the fresh green grass, looking better since summers drought. https://t.co/B4R1ulIHYh
So after I checked the field site I headed to the lab, it's not much to look at from the outside. https://t.co/CVbJ1aUrRG
I mentioned the labs not much to look at from the outside, much better inside. It's actually a temporary facility in place of the labs we lost due to the Christchurch quakes. A replacement lab building has yet to be built. https://t.co/XauZgXnyt1
On the walls along the corridor are some art works a colleague commissioned using DNA electrophoresis gels from his lab https://t.co/NO5L8HsJiL
The most used items of equipment in the lab are the 3D printer (https://t.co/WKME53HINr), electro-spinning apparatus (https://t.co/VQivx2AxPB) and Ussing chambers (https://t.co/RAMSKt0aN0). https://t.co/5imPcarar4
We use the 3D printer quite a lot for small items of lab equipment, a small bowl for coating seeds and granules, and electropun nanofiber collectors https://t.co/tglq0DuhHG
We've 3D printed sheep brain models; on the left a sheep with Batten disease (https://t.co/IC4gZnjKUR), the middle from a normal sheep and the right a sheep that had a gene therapy to help halt the progression of the disease. Gene therapy - that's an amazing nanotechnology! https://t.co/3dLNyzJDMZ
After I'd finished in the lab I took a small drive in the country 5 mins down the road to drop some samples of at a company a former PhD student of mine managers a field site for. https://t.co/6Qovw7sPlC
And then a drive home for lunch back through the busy metropolis that is the main shopping center of the town I live in (Lincoln) https://t.co/TgeOHcYH1d
I'll talk more about electro spinning nanofibers tomorrow
A project unrelated to fertilizer, sodium nitrate (https://t.co/GLhdb9Vjxp) granules coated with zein (https://t.co/fQhbCZspdV) had problems with cracks in the coat. While we found an excipient that solved the problem it got us thinking about alternate nanotechnology solutions https://t.co/968IwlFcqq
RT @TorieRobinson10: @gabrilignani has a truly exciting role: running his own #epilepsy research lab (@LignaniLab_UCL) at @ucl @QSNeurosurg…
[admin] "Fertilizers to Vaccines - Materials Science is Everywhere" Podcast #50, in conversation with @CraigBuntNZ is out now - https://t.co/MtWBF7jEkf
Yesterday I started tweeting about improving the formulation for a coated granule. This pic is an SEM (https://t.co/Dwwxy1ftbg) of zein coated sodium nitrate https://t.co/ULkd6Dnbuh
A bit of background to the project. NZ has some very unique native animals, it's a land of birds, insects and small vertebrates. No snakes, only 1 poisonous insect, ... https://t.co/yU1oXAqm4R
And only two native land mammals (both very small bats), and the odd seal pup that wanders up into the bush (seen here by my son when out hiking near the coast) .... https://t.co/Tpd4k8AIoq
These on the other hand are all introduced mammals and most have become pests that endanger the native flora and fauna. 3 species of mustelid, 5 deer, thar and chamois, goats, feral pigs/cats/horses, 3 rats, mice, 2 rabbits, hedgehog, wallaby, and the Australian possum https://t.co/pb7d8D21Qe
There is a drive by the NZ government to protect our endangered flora and fauna "Predator Free 2050"https://t.co/YWXngdz16H
Sodium nitrate is an agent to control feral pigs and the Australian possum. But it's unstable and bitter. While the initial zein coating formulation did improve compatibility and stability it wasn't sufficient. Formulation improvements were tested, some made the coat crack... https://t.co/DAc3OnYj14
One new formulation (left) not only improved the coat (wrinkled but full cover) compared to the original (right) formulation (smother but with regions of poor cover) it improved the manufacture process, this got us thinking... https://t.co/iiJIuK4GND
No matter how good you do manage to coat something if there are any cracks at all the coating will fail. A typical way to address this is to make you coat extra thick (requiring more materials, time to manufacture and reducing the proportion of coated material to coat)... https://t.co/ZViB0WsjUY
So we started thinking; could we make agricultural formulations and unlike the one in the picture here we'd use less coating material (giving a cost saving and better loading of coated material), could it be self-healing (if a crack develops can the coating fix itself)? https://t.co/MmmBsWYVES
And we think we can, we've a 3yr project (Multifunctional nano-coatings for sustainable agriculture applications) researching this. The intellectual property associated with the project is protected so I can only mention what's in previous press releases. https://t.co/g1HzjAxSqo
Our lab (https://t.co/aes3BSvpse) pic from a few years ago; alumni* and current team. Left to right; Elena* (PhD-endophytes), Jayanthi (PhD-ocular drug delivery), Min Min* (PhD-probiotics), Sally (soil scientist post-doc), Ivy (PhD-formulation, now post-doc) https://t.co/1vzyMQjQKH
We're also looking at horticultural and veterinary applications for electrospun nanofibers (https://t.co/VQivx2S8H9). https://t.co/5ZWXEfWHpA
Our initial apparatus for making nanofibers; high voltage generator, syringe pump, and chamber (yes a fish tank)... https://t.co/Xns0O7q4a1
Produced fibers well but they didn't always land on the collector uniformly (stray fibers acting as minor discharge points, humidity and local weather conditions probably contributed to this) ... https://t.co/uWkfqEmp4V
So we 3D printed a rotating disc to which we place a sheet of aluminium foil. We've a draft paper describing how to manufacture this unit that I should (will) post on our lab website. https://t.co/4PcQzqw0AQ
Ivy completed her PhD recently and is now a post-doc in our lab has suggested I post a link to this "The importance of stupidity in scientific research" https://t.co/YGUTzRlJxB It was something she found very useful when doing her PhD
RT @ResourcefulHDR: @RealSci_Nano This is very good.
@tanya_microbio I printed last year and put it above my desk to!
Mōrena! Another great sunrise today https://t.co/2nqggMghBP
I had an appointment this morning at the campus medical center for an influenza vaccine. Excellent protocol at the station they're running out their side door, was required to hang around for 5 mins in the garden. Autumn here in the southern hemisphere of course. https://t.co/TOZyxXjrDQ
So I mentioned we electrospin nanofibers, using the apparatus we assembled from off the shelf and 3D printed items. We have two many areas of interest; applied uses such as agriculture and more fundamental investigations of nanofiber properties. https://t.co/riOxFh4lxG
We've look at apply nanofibers to plant seedlings (top plant) incorporating anti-feeding compounds or insect pathogenic fungal spores. The letting loose the caterpillars! Note the damage to lower seedling without nanofibers https://t.co/0dqno0aKYL
And we're looking at how choice of polymer and nanofiber structure can influence nanofiber properties. Often asessing water droplet contact angle as a measure of wet-ability https://t.co/dkZW6UZm3C
We've been looking at double layered nanofiber mats. One side we make using PEO so it can get wet and stick to a biological surface like inside the mouth. The otherside we make using PCL that's difficult to get wet. This way one side sticks the other side doesn't. https://t.co/Y0CtcPPM94
We can access just how difficult or easy it is to wet by the measuring the contact angle of a water dropped. The flatter the droplet the easier it is to get wet. https://t.co/LyE9AAZbBs
We can calculate the contact angle using a photo of the droplet and freely available software called ImageJ with a couple of add-ons https://t.co/eBsLdf6zYs
To take the photo we use a setup as described in this pic https://t.co/zuxBw5zA2S
@cleanroombro Dropsnake https://t.co/pFJrauneFK
Sunday morning walk in the country outside the town where I live. More coffee, then I'll find a sunny spot to tweet from. https://t.co/J9i8zHK0xc
I'd like to talk about initiating/maintaining research while dealing with big challenges like covid. In a way I was almost prepared for covid. The Christchurch earthquakes/ terroist attack, multiple management changes, poor funding/resources ... A decade of disruption in my life!
Worrying about covid feels very much like living through the Christchurch earthquakes; poor sleep, distracted thoughts, difficulty focusing, fuzzy brain. At the time of the quakes we called it "quake brain"
So for a few weeks leading up to and since stay at home was ordered in NZ I've expected nothing of myself or my team. We all need to deal with things in our own way; mine was making hand sanitizer and setting up a home office. Basically tidy a few things and do a little often.
What ever the new normal is (or return to the old normal) will need to be established before we can set ourselves concert targets (not aways the attitude of management sadly). Till them I remind myself of 3 good bits of advice I've had over the years from mentors..
1) don't worry if you can't do what you wanted to, just do something. 2) do something that you find exciting. 3) do a little often. Keep in contact with friends and if you find yourself at a road block ask around, someone will appreciate any offer of or request for assistance...
There's always someone who needs a manuscript edited (or someone who can help you with yours). Volunteer for a committee. Start scoping a review you may never submit. Or just do nothing, sometimes this has been the hardest but most effective thing I've ever done.
Speaking of maintaining/initiating research, ugggh funding! In NZ 10% success is a well funded scheme, so typically less that 1 in 10 applications successful. I can handle reject as well as the next person, but in NZ there's no feedback!
I prefer applying overseas for funding; two attempts to get an @OECD fellowship, twice rejected for USDA funding. All rejections came with feedback! So very happily submitting for a 3rd time the USDA application. NZ colleagues think I'm lying, they say feedback is a myth
[admin] Thank you Craig (@CraigBuntNZ) for an insightful week! Podcasts and more https://t.co/MtWBF7jEkf
Damien Leech
[admin] "Reading the Fine Print – How Material Science Informs Both Art and Manufacture" Please welcome Damien Leech (@dr_djleech ) https://t.co/f5teLu5UCP
Hey everyone! Damien @dr_djleech here, will start as I mean to go on - with an overuse of the gif function. https://t.co/XxiDHHy3WT
A bit of background - I did my PhD on models of the interactions between stacked layers of 2D materials. With a focus on the electronic structure of graphene, particularly in a bilayer form, and moire pattern formation. https://t.co/DFOMR2UZqc
If you've ever been remotely adjacent to work on graphene, you'll have probably seen the figure of a van der waals heterostructure represented as lego bricks. This stack of 2D materials is built layer-by-layer and has properties that depend on the stacking https://t.co/0Z4f13Gk46
But this simple picture misses out two of most interesting parts of the problem - how adjacent layers affect one another and what happens when the periodicity of the lego bricks don't match up. https://t.co/KDCe4jrCoj
Both graphene and hexagonal boron nitride have, yep, hexagonal structure.And this structure is very similar. So much so that hBN is the perfect substrate to place graphene onto to study the behavior of it - it's insulating so it doesn't interfere, flat, relatively easy to make... https://t.co/RHJ9JqfL9T
But there's a lattice constant mismatch of 1.8% and, over many hexagons, this makes all the difference. A moire pattern forms and a new periodicity arises, much larger than before - this has a subtle but very real effect on the electronic structure. https://t.co/wEKQ2fbEhB
This interaction changes depending on the materials used and orientation between them, giving us many avenues of manipulation. And vertically, we can just keep stacking - some groups are making mind-bogglingly complex stuff! https://t.co/j6zTm9hkgU
How does bilayer graphene come into all this? Well, when your stack is built, you are mostly locked in, in terms of properties. The materials, stacking and orientation won't change. But bilayer graphene has some symmetry breaking properties that make it distinct from monolayer...
Place bilayer graphene in a perpendicular electric field and the symmetry breaks, one layer has a differing on-site energy to the other. This causes a band gap to open, with a magnitude proportional the strength of the electric field. https://t.co/FdEGSZVGzX
Now you have an avenue for tuning the properties of a stack externally! It can produce all sorts of strange electronic behavior, including extremely flat energy bands... https://t.co/rHODUNseyU
One thing I always loved about 2D materials research was the ever-increasingly-obscure materials being suggested/isolated - from silicene to graphyne(?) to bismuthene(!?). It's really fascinating to keep up with! 2019 saw isolated plumbene! https://t.co/Mzpi7m9mce
So what's the 'I knew about them before they were cool' monolayers I should be keeping an eye out for next? Because I only really enjoyed stanene's first album.
After PhD, I moved 10 mins down the road to Bristol to work @CFPRresearch @UWEBristol on print technologies, alongside scientists, engineers, and even artists and craftspeople. It's a fascinating place! https://t.co/GYLZ079icK
The research in the centre encompasses print in all forms - going from additive manufacture and inkjet all the way to more traditional approaches like screen printing and letterpress. All for industry, academic research and even artistic use... https://t.co/FtJzhXeVea
This includes 3D printed ceramics, custom glassware, laser-dyed textiles, artist's books, colour perception, robotics driven design, texture mapping, jewelry production, stop-motion animation, maintaining/resurrecting dying crafts and manufacture processes... All sorts!
So how does a materials scientist even be useful when it comes to print technology? Printers, in all sorts of forms, are complex kit that often work on the premise that the ink you put in is well defined and consistent. Lest you go all Office Space on your printer... https://t.co/YbMsoAmGMb
Therefore ink characterisation is incredibly important and properties such as the rheology, surface tension and even colour all arise from effects on the micro/nano scale. First principles models can be really useful in determining what is going wrong! https://t.co/xTl4lETYiZ
There's this term 'printability' that contains all the vague concepts that make an ink printable. It's not usually strictly defined - notable exception is inkjet, where it's driven by the Ohnesorge number, which gives a thin window of opportunity! https://t.co/UOjCi0048c
By the way, 'ink' is another vague term used to describe whatever 'input material' you give the printer! It can be liquid ink, 3D printer filament, powders, chocolate...
But what do I do? Printing has a lot of history to it - there's been plenty of methods that have come and gone and a lot of lost knowledge there. I look at forgotten 19th century print methods with unique advantages and how we can revive and modernise them (Daguerreotype, 1837) https://t.co/g4mxrMk2gn
This time was particularly exciting as print was some sort of weird collision between print, photography, chemistry and physics. So the methods use elements of all of them. One focus is the Woodburytype - it's a relief print method that uses a gelatin and carbon black ink (1880) https://t.co/HEZVG4qq9b
The darkest regions of the print stick out from the page further than the lighter parts, trapping more pigment - it's very intuitive in terms of optics, but not very common in print. You can read more about the process here: https://t.co/hBacHunedd
@MaterialsDan Love this! Really fascinating read
RT @MaterialsDan: @RealSci_Nano This New Yorker article about printer science is a great read https://t.co/u7BmsEDsCZ
One aspect of updating old print processes is moving monochromatic processes to polychromatic. Colour perception is a whole field of its own that encompasses pigment chemistry, ambient optical conditions and even how the brain/eye combo reads and interprets these signals. https://t.co/3WTsdhLKQJ
This plot represents the response of the three types of cones in the human eye. They're not uniform at all and therefore neither is our interpretation. (Side note: some people have 4 cone types! As do plenty of animal species, in this case it is usually located toward the UV end) https://t.co/QgXKwdrR21
Using this knowledge, we can begin to map our colour perception. This horseshoe represents it, white is in the middle and colours become more purely monochromatic as you move towards the outside edges. There's a secret 3rd dimension to it, lightness, giving lighter/darker tones. https://t.co/NsFgtQlYWx
Tracking the outermost regions of the plot that we can reach defines a colour gamut, within which contains all the possible colours from that technique. sRGB is shown here, the standard digital colour space, reproducible by 99% of all digital monitors. https://t.co/2hiHzZvGbU
The Woodburytype has no photoactive element in the print and so very little fading occurs, giving surprisingly high-quality windows into 19th century life. Street Life of London (1876) gave 'direct communication with the people' in 'unvarnished language' https://t.co/GvmCGTM2ag
3D Printing? That's kind of a big thing, huh? More generally known as additive manufacture, you're probably familiar with fused deposition modelling process whereby plastic is selectively extruded from a heated print-head. https://t.co/E7wHpyQHBT
This works really well for a whole range of shapes and high-end printers are regularly getting beneath a 100 micron layer thicknesses for a handful of materials. The print is self-supporting so sometimes excess supports are added and removed after printing. https://t.co/JNOvYtPLXU
But theres other options - stereolithography uses laser to selectively cure photopolymers and can breach sub-50 micron layer thicknesses.Still requires supports and materials must contain a photopolymerizable component. Optical methods tend to be sharper! https://t.co/VIgcKwwFUI
Selective laser sintering spreads a 'powder' layer, uses a laser to sinter regions of it, and repeats for the next vertical layer. This means no supports! But requires an excess of the feed material and the object has to be 'excavated' from the powder. https://t.co/WWTk6jd15H
There's all sorts of others, but some of the most interesting are hybrid manufacture. This uses additive techniques to build the main bulk and then switches to subtractive in order to give a smooth finish and smaller feature sizes. https://t.co/uC6hpXiZd4
Additive manufacture loves three-lettered acronyms (FDM, SLA, SLS, FFF, EBM, STL...?) but usually you pick your technique based on the materials you want to print... So we'll talk about that in a bit!
And it probably goes without saying... But if you do have access to 3D printers at the moment, please look into local groups printing PPE! There's many amazing initiatives going on at the moment!
3D printing (FDM) typically utilises plastics like PLA and ABS - they're a standard. But some of the most fascinating research, for me, is when people use these printing platforms to print material that is 'unprintable'. Want a new coffee mug? Print one! https://t.co/QtOIsJ6mHD
Ceramic 3D printing tends to come in two flavors - an extrudable clay is formed or a powder base is selectively bound together via light/chemical reaction. It makes structures not traditionally possible and is used in both tableware and biomedical apps https://t.co/UqEkytMl7b
But what's really awesome here is the enthusiast community that exists for clay/ceramic printing. This wikifactory contains so much useful information, all on how you can modify your own setups and produce suitable clay inks. https://t.co/SXi6MyZB1j
RT @UniofBath: For the first time, labs around the world can 3D print their own precision microscopes to analyse samples and detect disease…
Ceramics not your thing? OK, how about bioprinting? This is loosely defined as the printing of biomaterials, ranging from directly (and carefully!) printing materials loaded with cells to constructing complex scaffolds that can later be seeded with cells. https://t.co/Z274rKf6vQ
This is an incredibly complex field, that requires expertise from a whole range of backgrounds. But the ultimate goal is the realisation of complex and biocompatible printed tissues. This paper sums it up far more eloquently than I can! https://t.co/jwAIH3i0Ur
But surprisingly, I have to refer to the literature for this field a lot. No one understands the rheological and optical properties of gels and soft materials (and particularly gelatin) better and so my work with gelatin is often propped up by these, frankly mind-blowing, papers. https://t.co/AzTJWorF6v
This, for instance, is just exceptionally cool! https://t.co/36UM9ERroM
And this really encapsulates that interdisciplinary approach that is so necessary for these sorts of complex problems! https://t.co/RfiPTwrR9f
Alright, how about printing chocolate instead? Fed up with delicious chocolate in simple shapes? Reprocess and print into all manner of shapes! This paper covers a custom setup for a chocolate extruder and explores the flow properties of chocolate inks. https://t.co/NWoPrAik83
This system is particularly interesting as it turns out the key here is in the temperature control, just as much as it is in the rheological control. It represents a fascinating test case into the effects of cooling and air flow on the print process... And it's delicious.... https://t.co/jOs4TxwISF
Currently working on a similar homebrew setup and making some progress (and a lot of mess). Just need more ink making supplies from @CadburyUK! https://t.co/doxBwX8eSW
No sweet tooth? Try 3D printed mash instead! Also includes NMR analysis! https://t.co/MFaQmlxfEW
[admin] podcast #52 with @dr_djleech is available now. "Reading the Fine Print – How Material Science Informs Both Art and Manufacture" https://t.co/f5teLu5UCP
Or print your own circuitry with marmite and vegemite. Honestly a contender for best paper title ever - '3D printing Vegemite and Marmite: Redefining “breadboards”' https://t.co/BZQYsZmQz4
Colour from pigments is one thing, but nature explores more complex setups quite commonly. The iridescent colours seen in beetles for instance arise from multi-layers reflectors of chitin/proteinous material. The thickness/structure determines colour and lets it varies with angle https://t.co/rv0bpWnx83
This paper looks at how this effect changes through the lifecycle of a particular type of beetle, mostly through optical characterisation. https://t.co/Dsn6dnPecD
Plants are a bit overlooked - but the buttercup produces a complex colour response based on a mixture of structural and pigmentary colour. This paper posits this is not only for visual signals, but also as a directed heating element! https://t.co/q5ToTJr9eG
If anyone knows of anymore interesting examples of structural colour please do share! Another commonly mentioned example is the goth-as-hell Queen of the Night tulips. https://t.co/Z2gRCrWI6V Listen hard enough while reading and you can hear Sisters of Mercy playing.
Nacre (mother of pearl) occurs on the inner layers of many mollusks. It consists of platelets bound in a matrix of biopolymers and produces the lustre seen on shells/pearls. An example below from a common flattop shell, with the upper patter scraped away. https://t.co/EJWlcfZE9w
This one I've never quite got my head around, because a lot of times you'll find shells that display this effect, but only in regions where the outer layer/pattern has been scraped away by wear and tear. It's mostly hidden! Any insights greatly appreciated!
Any interdisciplinary researchers? I'm interested in the sorts of hurdles you feel you generally face. Is it convincing journals your work is relevant? Maybe convincing conferences instead? Maybe even funding opportunities? Or is it more day-to-day sorts of things?
Alright so time has no meaning at the moment and I lost yesterday to one of those 'I've opened so many Stack Overflow tabs that I've forgotten which problem I was trying to solve' days. Will make up for it today. Goodbye sweet Quantum Espresso build, I hardly knew ye.
How are people finding the transition to online conferences/seminars? Currently running a seminar group (welcome to join if you want to hear about art/science/print) and it seems to be going alright. Any really good groups I should look into? Interested in all sorts of topics! https://t.co/19fgXMNYPz
Also, if you'd like to give an online talk to a group of artists/engineers/scientists, do let me know! Probably the biggest upside of this move to an online setup is that we've had contributions from across the globe and I'd love to get more materials/nano scientists involved
@AtiyaahDollfie @MySci_PK Coffee consumption has gone way up - coffee quality way down. Those lines crossed somewhere in mid-April I think.
The online talk setup works quite well - less cramming into cold lecture rooms and spilling coffee while navigating chairs. Only issue is - how does networking work now? Some chance meetings have been really useful, for me at least. Haven't really seen an alternative around.
[admin] Thank you Damien for introducing us to the world of fine print and a materials scientist's take on it. Give Damien a follow - @dr_djleech https://t.co/AcKJJhIrYo
James Armstrong
[admin] "Making Cells Dance - Acoustic Tissue Engineering" Welcome James @jrmstrng Listen to the podcast #53 to learn what's coming youe way this week - https://t.co/UzpvJUbbwT
Hi everyone at RealSci_Nano - my name is James Armstrong @jrmstrng, I'm a research fellow at @ImperialCollege and this week I'll be tweeting about some of my favourite science things - #cells #sound #3Dprinting and more!
So I learnt about RealSci_Nano through my former colleague Amy (aka @DrTinyTaps) who curated this account in week 39. If you missed it first time round then I recommend checking it out here - https://t.co/isbMODiynl
Shout out also to Gregor (@FuhrmannGregor), another of my former colleagues and RealSci_Nano curator just a few weeks ago - https://t.co/Q4RivDhv03
So before I launch into the science tomorrow, let me introduce myself! I am a proud dad to two kids, a keen footballer and traveler, and reluctant jogger. I feel very lucky to be in my dream job, where I can do so many of the things I love - learning, creating and educating!
I'll talk about this more on Saturday but I've recently been co-organising these #Virtual #Seminars in #Biomedical #Science with @BrianAguado. We kicked off with two fantastic postdoc talks last week and can't wait for the rest. Please share this and join us every Thurs in May! https://t.co/u3R4PGdv3t
OK science time! This is a thread about how I “painted” stem cells during my PhD with the @perrimangroup. I chemically modified proteins so that they would “stick” to cells to give them superpowers (sort of)...check it out here in @NatureComms https://t.co/P3qG0lznEQ https://t.co/QVE5aahsa1
How did we do this? Well, cell surfaces are negatively charged, so if you make your protein positively charged then it will spontaneously bind through electrostatic interactions. Simple! But how do you go about making a protein positive...?
Well, proteins are made of positive, neutral and negative amino acids – these usually cancel each other out and you end up with a “net charge” that is either slightly negative or slightly positive. But we can mess with this!!
Some groups use genetic manipulation to switch out these amino acids and make #supercharged proteins. I particularly love this paper by the Liu group: https://t.co/ejFBmRPgeg
But we did something totally different. We took proteins and used a simple chemical reaction to turn the negative amino acids into positive ones – a process called #cationization
When we added these cationized proteins to cells, they stuck to the cell membrane! However, we could make even more protein stick by using a neat trick - attaching a surfactant to the surface of the cationized protein.
These proteins stick to the cell membrane through hydrophobic interactions - and stayed for over a week! Here is a picture of a stem cell "painted" with surfactant labelled green fluorescent protein. We estimated that there were around 6 billion proteins per cell! https://t.co/KIyfVqyILv
So why is this useful? Well, we wanted to see if this could address a big problem in tissue engineering - the starvation of cells in the middle of big tissues. We figured that we could use our method to "oxygenate" our cells with myoglobin...
So together with the Hollander group, I grew lots of chunks of cartilage using either "painted" cells or "unpainted" cells... https://t.co/hUIqQatvhA
...and to skip over a lot of work (!) this was the final result: the left column shows tissues grown with unpainted cells (big hole in the middle) while the right column shows tissues grown with painted cells (much smaller hole). https://t.co/y5N8VGePno
This means that we could grow big* tissue constructs simply by pre-treating the stem cells! This could be potentially used in the future to replace cartilage lost through osteoarthritis or sporting injury. *big = 5 x 6 mm which is pretty big for cartilage!
But what else can you do with this? Well the @perrimangroup attached surfactant-modified thrombin to stem cells to grow fibrin hydrogels from the cell surface, potentially offering a new route to wound healing...check it out here in @NatureComms: https://t.co/vh4fBmXRVI
@sciborgess @Pingosaurus and others then magnetized cells using cationized magnetoferritin. This took just 1 minute, with the cells responding to an external magnet and detectable by MRI...check it out here in @nanoscale_rsc: https://t.co/k9uEwHyokn ... more on magnets tomorrow!
I should also say that this bioconjugation method was adapted from some incredible work by @perrimangroup and @apsbrogan who used surfactants to make liquid solvent-free proteins. If you've not seen this before then definitely check it out here: https://t.co/eDQx0vSIkQ
We can also adapt cell modification strategies for the modification of extracellular vesicles. These tiny membrane-bound particles have potentially interesting therapeutic opportunities, and surface modification can allow in vivo targeting or imaging: 10.1021/acsnano.6b07607
This is (hopefully) a working link for the extracellular vesicle modification review, co-written with @maggieholme and published in @acsnano: https://t.co/Av9xOkw2Kf
So today's thread is on magnetizing proteins, DNA and cells - and how you can use this to build complex tissues! https://t.co/coO8OAg9EQ
As I mentioned yesterday, @sciborgess and I developed a new ultra-fast method for delivering #magnetic #nanoparticles to cells. These magnetized cells could be detected by MRI - offering a potential opportunity for tracking #stem #cell #therapies!
Other people have used magnetic fields to manipulate magnetized cells - I especially like this paper in @naturecomms, which used a magnetic "microtip" to cluster and stretch stem cells - this caused them to become more like heart cells! https://t.co/5bKhBjwvm5 https://t.co/HwQysR1AOx
However, there are problems with magnetic cell manipulation. Cells are relatively big (~0.01-0.02 mm) and to move them, you need quite a lot of magnetic nanoparticles - but lots of nanoparticles can harm the cell, or change the way it functions...
So @sciborgess and I thought - can we magnetize growth factors instead 🤔? Growth factors are proteins that can make cells produce a certain type of tissue (e.g. cartilage, bone)...if we made magnetic growth factors then we could move them and maybe build complex tissues!
An amazing PhD student (Chunching Li) made this reality! His secret was to cover the magnetic nanoparticles in a "sugar coating" which soaked up growth factors and then released them slowly over time. Just what we needed! Red = nanoparticle Blue = sugar Green = growth factor https://t.co/Y2K6EDGuNH
He used a magnet to make a gradient of bone-forming growth factors across a material full of #stem #cells. After 3 weeks: - The end with growth factor - turned into bone - The end without growth factor - turned into cartilage We made an "#osteochondral" (bone-cartilage) tissue! https://t.co/PBJ8AotV65
Why is this useful?? Well, #osteochondral tissue is often missing in damaged knees - which is incredibly painful. This is a potential way to grow replacement osteochondral tissue in the lab! Check out Chunching's @biomaterials_ paper here: https://t.co/S3u13cFCXX
We used a bone-forming growth factor - but if we switched this out for another growth factor then we could potentially make other #gradient #tissues! Any ideas, please let me know (DM @jrmstrng)!
[admin] "Making Cells Dance - Acoustic Tissue Engineering" @jrmstrng talking about his science on podcast episode #54, out now https://t.co/UzpvJUbbwT
Today’s #RealSci_Nano thread is all about my favourite topic and the tagline for this week – how to use sound to “make cells dance.” This is a video of cells patterned by an ultrasound wave...read on to hear more about how we can use this for #tissue #engineering! https://t.co/rpaRvMgZMx
What is going on here? Well, what we have here is a "standing wave" which means that we have made sound waves but they are not travelling. This creates static regions of pressure - some higher than usual, some lower than usual, and some unchanged.
This is a slightly unusual situation for cells to find themselves in! Cells in areas of high and low pressure will feel an "acoustic radiation force" which pushes them into areas of unchanged pressure. This is what we see in the video - the cells accumulate in the "nodal plane."
What is great about this is that you don't need to modify/label the cells or the culture media in any way! This works because the cells have a different density and compressibility to the surrounding liquid.
There are things that can mess with this - gravity, viscosity, cells sticking to things and an effect called acoustic streaming. A lot of what I do is trying to figure out how to get around these problems!
...but when you get the conditions right, you can start to pattern cells in gels. This is an image of cells all lined up in a collagen hydrogel. This is exciting because this means we can start making a patterned tissue! https://t.co/c3BkviERVE
We first used this to make muscle - because muscle is naturally made of parallel bundles of long cells. Using our sound waves, we were able to make something similar! If you are interested in this, see our Advanced Materials (@AdvSciNews) paper here: https://t.co/PJIdJqwE2F https://t.co/JCiwpkItgv
The possibilities for this are endless! I worked with @sonic_bruce and his team to make these patterning devices - they are easy to use and compatible with normal cell culture. By tuning the ultrasound properties we can make all sorts of different cell patterns! https://t.co/YO1i0FVMi9
I'm now working with my brilliant student @katya_pch to use these devices to make different patterned tissues and create smart cell culture systems!
Others have also worked with acoustic cell patterning - my favourite is this work by Peer Fischer's group published in Advanced Materials (@advscinews): https://t.co/Uj1hjnuISo Here they cleverly used acoustic holograms to make completely customized cell patterns! https://t.co/Jl7Ck4gI4J
If you are interested in using sound, magnets or light to build complex tissues then you can read more about it here in this @TrendsinBiotech review: https://t.co/CMZmzCVrO0
@badz_nithin Thanks and good question! People have looked into cell separation using sound + microfluidics. There is a whole @labonachip series about this field of "#acoustofluidics" (e.g. https://t.co/6fGqei9bAy). A nice example of acoustofluidic separation: https://t.co/DWb1sm1R4l).
@badz_nithin @LabonaChip But your idea of aqueous multiphase systems is interesting. The fluid density gradients would both separate the cells and also change the acoustic radiation force felt by the cells. If you set this up orthogonally, you could maybe get 2D separation, and resolve subpopulations?
@badz_nithin @LabonaChip Thanks for sending this over! An advantage would be the avoidance of paramagnetic salts - acoustics would work in unmodified media. The separation would also be different - acoustics would separate based on the cell compressibility and size (rather than how diamagnetic they are).
In today’s thread, I want to talk about some other fun things we do with sound! I've been lucky to work with a brilliant team (@NeleValeria @AcoustiCarolyn) on an exciting project using sound to trigger #enzyme #catalysis and #gelation! Read on for more details... https://t.co/91Yer3DLLX
Our idea was based on using #liposomes - small droplets that can be filled up with different "cargo" (e.g., chemicals, drugs). Under the right conditions, you can use ultrasound to release this cargo into the surrounding liquid. This cargo can then be used for many things!
For example, we used ultrasound to release a cargo of calcium ions - these ions could then stick to an enzyme (#transglutaminase) and activate it so that it could catalyze a chemical reaction. This was the first example of an ultrasound-triggered enzyme! But there is more...
...once the enzyme is activated, it can then turn a liquid solution into a gel (#fibrinogen)! This was only the second example of an ultrasound-triggered hydrogelation (the other one used radicals - ours didn't).
As usual, we should ask, why is this important? Well, enzymes are used all across industry and bio-sciences to catalyze chemical reactions, and hydrogels are commonly used as soft biomaterials for cell culture, tissue engineering, drug delivery, soft robotics and lots more...
...and now we have a new way to activate enzymes and make gels! Unlike a lot of light sources, ultrasound can pass through opaque walls and through the human body, which means we can now start to trigger these processes in previously inaccessible locations!
Another useful thing about this method is that it is "modular" - which means we are not limited to this exact system (calcium, transglutaminase, fibrinogen). We can switch out the cargo, the enzyme or the gels - something that we are exploring this now!
We also showed that you can stick the cargo-loaded liposomes onto tiny gas bubbles. Ultrasound can be used to expand, contract and burst the bubbles- which helps to release the cargo even better! https://t.co/UyDuChEwOk
I hope you enjoyed this thread! For more details, see our Advanced Materials @advscinews paper published earlier this year: https://t.co/h0n8CEeg7v Shout out also to @jono_woj (and others that aren't on Twitter) who helped make this happen!
@1Gy_too_many @NeleValeria @AcoustiCarolyn Thanks for reading the paper and that's a really excellent question that has got me thinking about this in a way that I hadn't before. For this transglutaminase system, the cargo is not a crosslinker, rather it activates the crosslinking process...
@1Gy_too_many @NeleValeria @AcoustiCarolyn ...which to me suggests that (in theory, under perfect conditions) the final crosslinking density should be the same regardless of calcium release - the only thing that will change is the gelation kinetics...@NeleValeria any thoughts?
In my last "science" thread, I want to talk about other ways to build complex tissues - and why this is so important! If this interests you, check out our Advanced Functional Materials review on complex tissue engineering, written with @liliangouyang: https://t.co/Awt9ZcTzpn https://t.co/Ozcra59Lbb
Why is complex tissue engineering important? Well, tissues are naturally complicated! They have layers, gradients, blood vessels, nerves, patterns of cells and lined-up fibres - all features that have evolved to keep the tissue healthy and play important functional roles!
The take-home message is: If we can't replicate this structural complexity, then our lab-grown tissues will simply not work as they do in nature - and we won't be able to use them to effectively replace or study natural tissues.
Luckily we have a lot of new methods for growing complex tissues. The review that I posted is about "bottom-up" methods. This means that we start with smaller "building blocks" - such as cells, organoids, fibres or sheets - and then assemble them into complex tissue structures.
I've already spoken in previous threads about "remote assembly" methods using sound, light, magnets. There are also "self-assembly" methods that use a particular property of the building block (e.g., their shape or chemistry) to spontaneously and predictably assemble!
However, you can do this in a far more controlled way by using a broad set of methods called "directed assembly". There are lots of examples of this - in fact, many methods used for tissue engineering (weaving, knitting, braiding) are borrowed from the textile industry! https://t.co/2NymcXDDNd
Like many people, my favourite directed assembly method is 3D #bioprinting! Here, the "ink" contain cells and/or materials, and the printer deposits the ink into custom shapes. I've worked with many smart people on some exciting printing projects. Here, I will share 2 of these!
The first of these was the development of a new type of ink with @perrimangroup @madelineburke3 and @BennyC. The problem we found was that some materials were "printable" and some materials were "cell-friendly" but rarely could materials do both jobs well!
So we decided to make a "hybrid ink" - containing a printable material (#pluronic) and a cell-friendly material (#alginate). Pluronic is quite unusual - it turns from a liquid to a gel as it heats up! This meant we could print a cold ink that would set on a warm (37 deg) stage.
We then washed our printed structure in a cool calcium bath, which did two things: - the calcium very quickly gelled the alginate. - the cooling washed away all the pluronic. This meant we could make large alginate structures (like the nose in this picture!). https://t.co/yvyKT00x7M
We included stem cells in this ink and use it to grow cartilage and bone tissue. For more info, check out our Advanced Healthcare Materials paper: https://t.co/Jx0bMeVEqs
I now want to talk about some awesome work, which was done with the amazing @liliangouyang! Here he addressed a big problem in tissue engineering: building tissues with blood vessels. Bioprinting is perfect for this as it allows you to build structures with open channels... https://t.co/7jbjdlvWgv
...however, a problem with open channels is that you then need to put blood vessel cells in and let them stick to the channel walls. This is difficult and doesn't always work, particularly if you are trying to build small and complicated vessels...
So what Liliang did was to use two materials - one filled with blood vessel cells to print tubes, and the other to print the surrounding tissue. The latter was then strongly gelled with UV light (it was GelMA for those interested).
...the clever bit was that the tube material was gelatin - which turns into a liquid when warmed! As the gelatin turned to liquid, it released the blood vessel cells, which then stuck onto the walls of the channels. This worked even for thin and complex blood vessel networks!
We call this method: "in situ endothelialization." If you are interested, check out our Advanced Functional Materials paper: https://t.co/tjH1SK5MQo
@badz_nithin @liliangouyang Hi, thanks for a great question! Yes we are definitely looking at combining ultrasound patterning and gradient casting - the application here could be for osteochondral tissue where you have aligned deep zone chondrocytes plus a collagen / gag / mineral gradient!
My last #RealSci_Nano thread! I want to talk about the important role of online seminars/conferences as free, open-access science during (and maybe after) this pandemic. I say this, as co-organizer (with @BrianAguado) of these #Virtual #Seminars in #Biomedical #Science 👇 https://t.co/u3R4PGdv3t
I totally love the #TissueTalk series by @GVNlab, where you get to see incredible Professors such as @burdicklab and @kaplan_lorax. But I feel that it's just as important for graduate #students and #postdocs to have a platform to disseminate their results and build their network!
This was the motivation behind the #Virtual #Seminars in #Biomedical #Science - and it is great to see so many similar initiatives focussing on early-career scientists. @gecedillo has compiled a great list of these events: https://t.co/6gYtjp8MWB
I really strongly feel that this helps “democratize” science – free-to-access and open to anyone with the internet. I’ve been lucky to attend some great in-person conferences over the years - but these are expensive to attend and are therefore exclusive to those with funding!
Another real issue with in-person conferences that needs to be discussed is that they can exclude those with care responsibilities or those with certain medical requirements. Providing talks online could make a major difference to these individuals.
On this note, there are steps that organizers can take to make sure that their online events are really accessible to all. You can’t pick a timezone to suit everyone – I myself have had to miss some really great talks due to parenting duties...
One option is to post talks online after the event so that they can be watched at a convenient time. With speaker permission - we are looking to do this with #virtual #seminars in #biomedical #science, and I know other organizers (such as @BEaTSResearch) have taken this approach.
In summary - while nothing beats an in-person conference, I truly think that online science conferences & seminars (#free, #accessible and #ecofriendly) – can play a big role during the pandemic and also in complementing in-person conferences in a post-COVID world! 🤞
To finish with a plug - I’m personally delighted to be giving an online seminar organized by @beatsresearch: https://t.co/2tWJPjkTFP and to be talking at this online symposium organized by @ClaudiaLoebel and @thewooj: https://t.co/X6yQd6zi4f Please join!
[admin] Thank you James for a wonderful week of science! Give him a follow @jrmstrng https://t.co/UzpvJUbbwT https://t.co/muYPRfWXN7
Upulie Divisekera
[admin] "From Nano to the Macro" We are delighted to welcome this week's curator - @upulie Read/listen to know what's coming your way https://t.co/KUtpUw80Zw
Hello Real Scientists Nano! My name is Upulie Divisekera (@upulie) and I'll be your curator this week! I can't wait to talk to you about nanoscience and my other scientific work in cancer research and endometriosis. I'll also be talking about my science communication work
But it's very early in the morning AND very late at night here in New Zealand, so I'll see you in a few hours!
Hello! Good to be back again. It's hard to figure out which timezones are best to talk to you but I'm just here to say hi before delving back into my work. It's late morning here in Auckland New Zealand, a really beautiful sunny day and I have meetings to prep for
I might start with talking about how I ended up in science. I'm a molecular biologist, I did my basic degree at the University of Melbourne in molecular biology/biochemistry and pharmacology. I did a Masters at the ANU and I have a doctoral thesis still to submit
I'm currently at the University of Auckland. Through various twists of fate, I've spent most of my professional life as a research assistant or student(!); and so I've ended up doing research in many different fields.
My Honours year was spent playing with Trypanosome parasites, I've worked in cancer genetics and immunology, spent time making antibodies on a near-industrial scale, studied fruit flies - which are surprisingly beautiful under a microscope - spent small stints in materials
science and my doctoral research is in nanoscience and drug delivery. And now I'm working on bioinformatics of endometriosis.
I did not expect that I would accidentally end up working in so many areas of science. I decided I wanted to be a scientist when I was 6-7, and like most kids I was keen on palaeontology. But I was keen on any kind of science I could read about and particularly space
I decided to be an astronomer, and was pursuing this single-mindedly until I was given a book on molecular biology. The principles of genetic engineering were so fascinating to me, and the possibility of reanimating extinct species so alluring that I switched immediately 🤣
I tried to perform my own experiments and even had a lab book set up for it. Still, my true loves are molecular biology, materials science and theoretical cosmology. We're allowed to have more than one, right?!
Anyway, that's just for starters. It hasn't been the straight path through science I expected, and I've missed being able to establish myself in a particular field; but it's also been a true privilege to be able to learn from so many scientists in so many fields.
When I decided to become a scientist at 7, I wanted to know how everything in the universe worked, from the tiniest atom to supermassive black holes, and how all the life forms function at the most basic level. It's impossible to know everything, but I've been fortunate enough
to explore so many fields of science, just as I always wanted to as a kid.
Just letting you know, @elonmusk, that we have a nanoscience #rocur and I'm hosting this week
Meeting done! Does anyone have questions and anything they'd really like me to talk about this week? I'll be talking about my cancer research, endometriosis and the nanoparticle-based drug delivery systems I was developing
It depends on which field of science you're in. Not all fields require a lot of advanced maths and programming. But the point of the training in science is to be good at learning and problem solving - so you can *learn* to be good at programming and maths https://t.co/1VWsspYA0Z
So how does a molecular biologist end up researching nanotech and dabbling in materials science? The scales involved are pretty similar, I would say. And some of the concepts.
Basically, it's all chemistry and crafting things from atoms. In biochemistry, it's molecules that have a biological function - tiny machines that are part of how the cell works
In materials science and nanotech, it's the design of molecules and objects at the nanoscale that can act as tiny machines. It's basically mimicking the evolution of life through the evolution of inorganic structures. These structures, and machines - they are all
designed to work the way biomolecules work; in a structured and ordered way. It fascinates me that we can do this with inorganic materials. It's also kind of fun to figure out what we can make and ways to make these devices
So what is "inorganic" vs "organic?" Organic chemistry isn't pesticide free range chemistry 🤣 sorry basically, organic chemistry involves carbon chemistry; and inorganic chemistry covers everything else.
Most of the huge biomolecules in our bodies and in all life are carbon based - carbon is an incredibly flexible atom. Most of the materials we use in nanotech are not carbon based, but can have some carbon components. But they can be made of metals - silver, gold, titanium -
or made of silica - the atomic cousin of carbon - and so many other materials. Some of these devices are also made of organic molecules. What's so fascinating about it is that you can make use of the chemical properties of each of these substances to design particular devices
[admin] "From Nano to the Macro" @upulie talks about the science and more, podcast #56 out now https://t.co/KUtpUw80Zw
Sorry I've been quiet, tweeps! I've been unwell.
RT @realscientists: [admin] Are you a materials and/or nano scientist? Do you like to talk about your research? Do you want to feature o…
Hellloooo everyone! Sorry for the silence at my end, I've had a bit of a cold and felt exhausted for a few days. But I want to talk to you for a bit even though it's about 2.30am where I am
So I spoke earlier about how we can use inorganic materials to mimic organic molecules. Think of it this way - instead of a biomolecules like a protein, an enzyme - you can try to make something that does the same thing, but it's made of a metal or silica - something inorganic
and as a biologist, that is just amazing to me. For example, you can actually make tiny nanoparticles that can be used as catalysts - like enzymes . Or you can make gold nanoparticles of any shape or size you like - bipyramids, stars, spikes, spheres, rods - by just using
chemical processes. It's *almost* like alchemy. So what does cancer research have to do with nanotech?
We want to take what we know about cancer and its weaknesses and create treatments that target those weaknesses - you can think of it like looking for chinks in the dragon's armour
We know what some of these chinks are. But with nanotech, you can be creative about how you deliver an attack - or an arrow to bring the dragon down.[ all i can think of right now is The Hobbit]
So what are some of those ways we can beat the cancer dragon? We know that chemotherapies are really effective, but while they attack fast growing cells like cancer, they can also attack healthy tissue in the body - this is why chemo takes a lot out of patients
So what would be ideal? We have chemotherapies - and other anti-cancer therapies - and we'd like to get them just to the cancer cells. Or even just most of it to just the cancer cells. Or we'd like to mark the cancer cells so we can find them without having to perform surgery
We could also mark the cancer cells - and destroy them - without invasive surgery. And finally, we could try to deliver gene therapy to the cancer cells, so that we can modulate genes that can shut the cancer down.
How would we do this? I have one word: nanotechnology. Tune in tomorrow to find out more.
Before I talk about how we can attack the cancer dragon, does anyone have questions? Let me know if something was unclear, I will do my best to explain
How can nanotech slay the cancer dragon? With gold.
Of all the elements on earth, I never expected that the most venerated and valuable metal to be an almost magical substance with multiple properties that would make it ideal for attaching drugs, attacking cells, converting energy.
Gold is actually quite non-reactive and can be turned into a range of nanoparticle shapes. It can be coated in antibodies and nucleic acids, modified so you can attach other drugs. It's surprisingly handy. Studies about its toxicity aren't extensive though
It turns out that the shape of a gold nanoparticle matters; and each shape has unique properties. For starters, the colours of different particle shapes differ.
Colloidal suspensions of gold nanoparticles don't look like gold. The particle size is so small, at the nanometer level, that they interact with light in a very specific way, producing what's called a surface plasmon resonance (SPR). We can use this to identify particles, to
make barcodes made of gold; devices made of gold. We can use it to characterise gold particles with different coatings, and so on.
So, the colours of gold particle suspensions: stars: green bipyramids: brown spheres: depending on the size, anything from brick red to maroon to purple 1-5 nm: brick red 10-25 nm: blood red 30-40 nm: dark red towards maroon 45-upwards: purple
capsule-shaped nanorods of gold: green. Well, gold nanoparticles are colourful, and you can do some pretty great and specific surface modifications to them. But what's even more fascinating is that some particles can actually convert energy.
Gold nanorods can be exposed to laser light at certain wavelengths, and they'll convert that energy down to heat. But not just a little heat, a lot of heat. Heat that can burn.
One of the therapies developed by my colleague was gold nanorods that used an aptamer to target the rods to a specific kind of cancer cell. A low intensity laser was shone on the sample; the energy was converted by the nanorods into heat that destroyed the cancer cells
Isn't that nifty? It's a very simple and elegant way to destroy the cells; and the aptamer made all the difference because it was selected specifically target that cancer cell. This is just one of the ways we can use gold nanoparticles to treat cancer.
Another way to treat cancer cells is to blast them with gold nanoparticles with chemotherapies, gene therapies or antibodies attached to them. These therapies are aimed at killing the cancer cell; and the gold nanoparticle is used to attach the therapy and deliver it
This is a basic principle - attaching an existing therapy to a nanoparticle - that's being developed for treating cancer and other diseases that need a little extra effort to treat. It's basically making teeny tiny nanocapsules - nanopills! - to treat disease.
And you don't have to just use gold - you can use so many kinds of materials to make these tiny nanopills - polymers, chitin, silica, squishy heat reactive polymers, and other materials that you can use to make millions of regular particles and attach therapies to.
This is the basic principle of using nanotech in drug delivery - and why a molecular biologist can end up working in this field (also, it turns out that engineers are not always keen to work with cells).
@MysterMyke Hmm...seems a bit unusual as this hasn't reached the clinic yet?
[admin] Thank you @upulie for a wonderful week of nanoscience. Podcasts and more - https://t.co/KUtpUw80Zw
Chris Bowen
[admin] "Wonderful World of Smart Materials" Please welcome Materials Professor at @UniofBath - @BowenNEMESIS Listen to the podcast #57 to know what is coming your way this week https://t.co/A6X3SoKdxh
Good morning everyone. I'll be hosting this week and will try my best to discuss materials, including ferroelectric and piezoelectric materials. It is a bit early, so I will try and wake up first.
The direct piezoelectric effect relates to materials that develop a charge when subjected to a mechanical stress.
Applications for the direct effect include sensors of force, pressure and acceleration. Microphones and hydrophones too. If you have used a gas lighter that generates as spark when you press it, that's also probably piezoelectric.
I've been for a walk around Bath, which is where I live in the UK. Earlier I discussed the direct piezoelectric effect. My next posts will be on the indirect piezoelectric effect. https://t.co/vVrv4j1NQG
The indirect (or converse) piezoelectric effect relates to the piezoelectric material developing a strain under the application of an electric field.
Applications include actuators, nano-positioners, speakers, active SONAR (to send out the 'ping'), ultrasonic baths, nebulisers, & fuel injectors. If you ever received a card that played a tune when you opened it, it probably used a piezoelectric buzzer, like the one below. https://t.co/gZHIcTnVoj
@palebluedot92 It will be a ferroelectric ceramic material based on lead zirconate titanate (PZT).
So, why do certain materials exhibit piezoelectric properties? Well, it is usually a lack of symmetry in ionic materials.
An example is lead zirconate titanate (PZT). At high temperatures (left image) the crystal structure is cubic/symmetric and non-piezoelectric. But on cooling is becomes tetragonal (right image) and you can see the black ion (Zr4+ or Ti4+) is displaced upwards, forming a dipole. https://t.co/yS8Gn8vhrd
It is this dipole that provides the material with a direct or indirect piezoelectric response.
In a material like quartz (SiO2) it is a little different, since in the stress free state the structure is symmetrical. It is the application of stress or field in a specific direction that leads to a loss of symmetry.
For this tetragonal structure the black Zr4+ or Ti4+ ion can displace up, down, left, right and in and out of the image above. So, the dipole can be aligned in six possible directions.
There are other crystal structures, but I find the tetragonal easier to visualise and it is important for materials such as PZT and barium titanate. For the rhombohedral phase the dipole can be along the eight possible diagonal directions.
We can now imagine that a dipole is created from some asymmetry in the crystal structure. How do we ensure that all dipoles are aligned in the same direction in a piezoelectric device? For materials like quartz, AlN, GaN we must use in single crystal or highly aligned form.
We have seen that one way to ensure dipoles are aligned across a material is to use single crystals cut in an appropriate direction (crystal 'cuts'). For polycrystalline materials, we can align the dipoles in materials called ferroelectrics (a sub-class of piezoelectrics).
Ferroelectrics are special, as the dipole and polarisation direction can be switched by an applied electric field. For example, the black Zr4+ or T4+ in the right image can by moved up or down by changing the direction of the electric field applied across it. https://t.co/J1cccXj7vr
A polycrystalline ferroelectric can be made piezoelectric by a 'poling' process. Initially, dipoles are randomly oriented (left image). We apply an electric field at elevated temperature to switch dipoles (middle), then cool and remove the field (right) to polarise the material. https://t.co/hbwGWKFDZY
Lots of advantages. No need for crystals cut in specific directions, so you can create a variety of shaped ceramics and chose your polarisation direction later. Polycrystalline ceramics relatively low cost. The high degree of polarisation in ferroelectrics also makes them active.
Examples of ferroelectric ceramics include lead zirconate titanate (PZT) and barium titanate. There are ferroelectric polymers too, like PVDF. All ferroelectrics can be made piezoelectric, if poled. Hence they are a sub-class of piezoelectrics.
For example you can make tubular shapes and pole radially for nanopositioners, AFM etc. Not easy to do that with a non-ferroelectric single crystal. https://t.co/FLCmNNjpN4
RT @RealSci_Nano: For example you can make tubular shapes and pole radially for nanopositioners, AFM etc. Not easy to do that with a non-f…
RT @ProfRachelGaN: @RealSci_Nano Reckon that's sufficient excuse to share a hexapod video - cool example of nano positioners....https://t.c…
[admin] "Wonderful World of Smart Materials" Listen to Chris (@BowenNEMESIS ) talk about his science on podcast #58 https://t.co/A6X3SoKdxh
Once we have a poled ferroelectric we can apply an electric field for actuation. Apply the field in the poling direction for extension; imagine moving that black Ti4+ or Zr4+ further away from centre. Apply field in opposing direction for contraction, pushing ion to centre. https://t.co/AgX7MfOgCs
@HelmanDaniel Good point, used the term 'usually' here with an eye on the ferroelectric ceramics. Any dipole / asymmetry will do, for example PVDF polymer due to H and F.
What sort of strain levels can we achieve? For PZT, a rule of thumb is that the maximum strain at the maximum applied electric field of ~2-3 kV/mm is ~0.1%. That's 1μm displacement for every 1mm in length. The multi-layer actuator below is 9mm long and max displacement is 9μm. https://t.co/uOflmbA9M5
The strain is small, but the force is large as the ceramic is stiff. For this small device the 'blocking force' is 3.5kN. Note: The 9μm displacement is a 'free displacement' at zero force, while the 3.5kN blocking force is at zero displacement. You can't have both at same time.
As the field is mainly moving the ion, it has potential to operate at high frequencies. This 10x10x9mm device resonates at 152kHz. So high force, small strain over large frequency range.
Yesterday we applied an electric field to our poled ferroelectric for actuation. Today we consider applying a mechanical load to develop a charge for sensing - the direct effect. If we apply a stress we now develop a charge and potential difference across the material.
The amount of charge is proportional to applied stress and the sign of the potential difference changes with direction of stress. Great for sensing. It always seemed strange how charge and current could flow in a sensor circuit, as the ceramic is an excellent insulator. https://t.co/1gXpbrihTA
Imagine the poled ferroectric with conductive electrodes at top/bottom. Screening charges collect at top/bottom to balance the polarised ceramic (left image). If we compress and reduce the level of ceramic polarisation, some screening charges are now free to flow (right image). https://t.co/tHBORkrluy
Charge (Q) generated is proportional to stress. Since current is dQ/dt then short circuit current is proportional to rate of change of stress (dStress/dt). Potential (V) across ceramic at open circuit is proportional to stress (since Q=CV for capacitor).
The ceramics are very good insulators, but do have a finite conductivity. Therefore they are typically used for dynamic forces - they are not used for static forces/pressures as the charge/potential across the ceramic will slowly decay and be lost.
I guess a key point is that the change in polarisation with stress leads to the generation of piezoelectric charge for mechanical sensing. Tomorrow, we will see we can also have a change in polarisation with temperature. The pyroelectric charge can be used for thermal sensing.
@JamieWHB In this case the high temperature phase is cubic and the polarised phase is tetragonal. So as you heat I guess it is getting closer to cubic and the dipole shrinks. https://t.co/GBJ5lW4ZjS
We have seen all poled ferroelectrics are piezoelectric. These materials are also pyroelectric, where the change in polarisation with temperature leads to a current flow. The direction of current changes with heating (polarisation fall) or cooling (polarisation increase). https://t.co/biaRQklKRo
Applications here include thermal/people detectors and thermal imaging. If a door has automatically opened as you walked towards it, a pyroelectric detector has probably been used to detect your body heat.
Let's consider a PVDF element 10mm in diameter, 0.1mm thick subjected to a 1K temperature change. The pyroelectric coefficient provides the charge per unit temperature change and area (left equation). Knowing the capacitance (middle equation) we can also calculate the voltage. https://t.co/XMxkHFOlpY
Notice the charge is proportional to area (and not thickness). This makes sense as it is the surface charge we discussed earlier. The voltage is proportional to thickness (and not area) , since the surface charge is more widely separated.
Let's consider the 10mm diameter PVDF element, 0.1mm thick and subjected to a 1K temperature change. Using the equations, the open circuit voltage is ~33V.
I can't go into the lab at moment, but here is a pyroelectric in my garden. The solar panel harvests sunlight and the LEDs are switched on at night when body heat changes the polarisation of the pyro-sensor (see central dome lens). Has worked for 3yrs with no battery replacement. https://t.co/d6jV49XQaT
RT @JoFeanelwa: @RealSci_Nano That's why when I was too cold all the time, automatic doors couldn't see me 😫
RT @BowenNEMESIS: Evening walk and look around the garden. Have a nice weekend. https://t.co/yj2kxOyOgB
We have seen that the pyroelectric and piezoelectric signals originate from the change in polarisation of the material with temperature or stress. Therefore we need to take care to screen piezo-sensors from thermal signals and pyro-sensors from mechanical signals.
So let's summarise, it is the weekend after all. 1. Ferroelectrics can have their polarisation direction switched by an applied electric field. All poled ferroelectrics are both piezoelectric and pyroelectric. Examples are PZT and BaTiO3. https://t.co/7i2dPCFZ44
2. There are materials, like ZnO, AlN, and GaN, that are polarised but are non-ferroelectric. As you cannot switch the polarisation direction with a field we must use in single crystal like form. They are both piezoelectric and pyroelectric. https://t.co/F7eXv72Kpz
3. There are materials, like quartz, which are only polarised after applying a mechanical load. As they are non-ferroelectric, they must be used in single crystal form. As they are not polarised in the stress free state, they do not exhibit significant pyroelectrict effects. https://t.co/vZ7KIpTgs5
One advantage of quartz here then, less susceptible to thermal changes.
I will try an experiment later tonight, when it is dark. I will see if I make the pyroelectric person sensor activate the LEDs by mechanical tapping to induce a piezoelectric signal. I need to sneak up to it first without my body heat setting it off. https://t.co/FiRA1jS5Zf
Ah, seems to work. The pyroelectric detector is facing other way and I tap on back (with high tech spoon) to set it off. https://t.co/fVL5sOMaXz
RT @RealSci_Nano: Ah, seems to work. The pyroelectric detector is facing other way and I tap on back (with high tech spoon) to set it off.…
I think today is my last day here. That's good, as you now know more or less everything I know myself. Hwyl fawr ('good bye' in Welsh) and take care.
[admin] Thank you Chris for a very ifnormative week and taking us into the wonderful world of smart materials. Do give @BowenNEMESIS a follow! podcasts and mroe - https://t.co/A6X3SoKdxh
Candice Majewski
[admin] "Cutting Through the Hype of 3D Printing" Please welcome our first curator of this month @CandiceMajewski 🎉 🎙️🎧- https://t.co/XtQRBdQSqu
RT @RealSci_Nano: [admin] Sign up here to take over this account and feature on out podcasts. https://t.co/RtNquW2jCs
Hi everyone! It's @CandiceMajewski taking over the account for the week, talking about #3DPrinting and the importance of materials. If you fancy learning more about this, have questions, or just want to chat about it, come on over!
I won't be Tweeting a lot from here today, as I try to keep weekends free to spend with my husband (Bret) and our dog (Reggie). This is them earlier in the week while Bret was trying to work... https://t.co/W0srbeqrhj
We're both lucky enough to be able to work from home at the moment, and Reggie is good at reminding us of the importance of taking regular breaks...
This week on the account I'll tell you a bit about me and my journey so far, and introduce you to the members of my team and what they do (we all know these are the people who actually make the research happen), and then we'll talk in some more detail about #3DPrinting
While I'm here, if anyone is working in this area and would like a signal boost please join in the conversation and drop me a Tweet with who you are and what you do. That way we can all see who's out there doing cool #3DPrinting research!
Before I go for now, let me just share two important things. First, this Tweet from @i_jayas highlighting a document from @erinmaochu and @sheffdocfest full of resources to learn about and support Black Lives Matter: https://t.co/B3uIv3K1BV
And a reminder that this month is Pride month and to stand in solidarity with our LGBT+ friends, colleagues, students and strangers. In case you (like me) didn't know the background to the Progress Pride flag, there's a good description here: https://t.co/d97LypQ4I0
I'm off for a bit now but I'll be back properly tomorrow, so I'll hope to chat to some of you then 👍
Hi again everyone, I'm back to start chatting about #3DPrinting! First off I thought I'd tell you a bit about me and my team. People are at the heart of any good research, so I'll tell you a bit about each of us and what we do throughout the day.
Before I start on that, a little bit about my journey to where I am. I'm the first to admit that much of my route so far was purely accidental, so don't let anyone tell you you must always have a clear plan!
I did an Engineering degree mainly because my careers advisor suggested it (thank you Mr. Smith!), and discovered #3DPrinting during the last couple of months of the course. Thank you to Dr Karen Williams who organised a two hour guest lecture on it and started me on this route!
During that lecture I was *BLOWN AWAY* by the many possibilities for how and where #3DPrinting could make a difference. I think I spent about 2 hours that evening going over all of it to my closest friends, and realised this felt like much more than a passing fascination.
Up to this point I'd found Engineering passably interesting, but I wasn't the best-performing student, and I wasn't grabbed by anything in particular. Finding something I was so excited about was a real novelty and I just sort of knew I had to go and do something with it...
So here's where a lot of luck came in. A new Masters course was just starting up in this area, so I was able to join that straight after Uni. Then my Masters supervisor had some PhD and post-doc positions going, which meant I was in a relatively secure position.
By this point I knew I wanted to consider going down an academic career route, so I started looking for ways to prepare for this - teaching opportunities, getting involved with some Departmental and/or University administration activities etc.
(If you're also considering a career in academia, it;s worth looking out for these things too. Don't be afraid to ask academics if there are things you can do, just make sure you're officially recognised for them so they can go on your CV/resume...)
Anyway, all of this culminated in my first (and current) academic position when a small group of us moved to @SheffMechEng to build up our #3DPrinting activities. I'm now in charge of our Advanced Polymer Sintering lab, and I'll tell you more about our research during this week.
Throughout the week please feel free to ask questions, tell us about your own career journey, or anything else you'd like to discuss. I'll be back in a little while to start introducing you to the members of our team and what they do!
First up from our group, our two awesome technicians, Kurt and Wendy! These are the people who keep the lab running smoothly and safely, and are the go-to people when anything's not going how we'd expect it to.
Wendy Birtwistle (@Rohilla) is in charge of our Laser Sintering system (more about that later) and material characterisation equipment, as well as doing a lot of training, health and safety work, managing resources, and lots of other things I'm probably forgetting to mention. https://t.co/e2UEUBsA1y
As well as #3DPrinting expertise, she has a background in electronics and used to manage the Faculty's flight simulator. She was also our Department's first female technician, and has plenty of stories to tell about how the Department has changed since she started!
Kurt Bonser is our High Speed Sintering expert (again more on that later). He joined the Department not long after I did, and quickly picked up the details of the High Speed sintering process - there's very little he doesn't know about how it works! https://t.co/wZjNVIE13x
He's also great at taking things apart and fixing them, which has come in handy when he's been working on the design and build of new test systems at small and large scales, and he's super persistent when working on tough problems!
Back in a bit when I'll introduce you to the other members of our team, in alphabetical order so as to be fair to everyone!
Time to introduce the other members of our group. First up, Talal Al-Ghamdi. Talal is one of my PhD students, working on understanding some of the specific properties affecting performance of polymer powders in our processes. I can't say too much as he's sponsored by his... https://t.co/OrjdSxfThA
company, but watch this space. He recently passed his first year review (well done Talal!) and he and his wife also welcomed their second child into their family not that long ago :)
Next up is Ryan Brown. He's been with us for quite a while now, and is currently working on his PhD corrections after passing his viva remotely a few weeks ago (well done Ryan!).
His PhD was sponsored through one of our CDT programmes and focused on crystallisation of polymers in our High Speed Sintering process. He's now working on some other research projects within our team, and has been involved in quite a few of our Outreach projects too :)
Next up, Adam Gothorp. Adam is a Maths graduate, and is working on his PhD investigating the use of Bayesian statistics to help understand material behaviour in some of our #3DPrinting processes. It's been fun working with Adam (and Eleanor Stillman and Paul Blackwell, his... https://t.co/0jprwsjAUn
other supervisors in our Maths Department), as I've had to learn a lot about how we each use terminology, assumptions about data and a whole heap of other things!
Now we have Karla Huerta Lucio, who's just submitted her PhD thesis investigating the use of #3DPrinting for personalisation of hand-held assistive devices. She joined us a few years ago with a background and interests in design. https://t.co/R1TZXSelq5
She and her husband were joined by their first baby during this time, so major credit to her for juggling being a first time mum with working on her PhD!
Next we have Oliver Leete. Oliver is about halfway through his PhD with us, and he's working on producing thermal models of our High Speed Sintering process. This is important as it can ultimately help us to understand the contributions different energy sources make on quality. https://t.co/yTt5idpbCL
Oliver's the go-to person for any kind of engineering tool you might need, and is always interested in the strength of parts and the ways in which they fail. Oh, and that's #NotHisCat...
Next up is Maha Omran. She's based in @ShefDentistry and is nearing the end of her PhD investigating materials for production of 3D Printed orbital floor implants. This has meant she's needed to get to grips with both Engineering and micro-biology, in order to find materials... https://t.co/89eFMKSMbL
which are both anti-microbial and encourage cell growth. Her main supervisor is @Cheryl_A_Miller, alongside @LunchBobs, @microshep and Caroline Harrison, so she's got her hands full with all of us!
And here's Alec Shackleford. Alec completed his PhD with a different supervisor, working on Positron Annihilation Lifetime Spectroscopy (PALS). He ended up working with us once he submitted his thesis, when he suggested that we could use PALS to characterise our 3DPrinted parts
As part of this he and one of my PhD students (James) were able to spend a couple of days on the positron beam at @HZDR_Dresden, so thank you to the team there for allowing us access - some really interesting results to come!
And here's Rhys Williams. Rhys just completed his PhD in a different group within our Department, investigating the application of halloysite clay nanotubes in epoxy resin nanocomposites. Since submitting his thesis he's been working with us to develop an understanding of how... https://t.co/xao4kif6eq
ink behaves in our High Speed Sintering process, and offering advice and support relating to chemical & material characterisation techniques/analysis. His chemistry expertise in particular has been really invaluable to us as a group, and we've all learned a lot from him!
Whoops, I forgot to attach the photo, so here it is! https://t.co/HaYxZjJ1f1 https://t.co/m2XUoALyrl
Next up is James Wingham. James is another one of my PhD students, and he's investigating the potential for introducing anti-bacterial functionality into our #3DPrinted parts (@microshep is his other supervisor). He's also involved in a lot of teaching activities within our... https://t.co/FlS0YXUGRq
Department, as well as taking a keen interest in Outreach. If anyone remembers the national @88Pianists activity we did last year, James was the one who took charge of designing and manufacturing all of our Sheffield mechanisms!
And last but by no means least, Zicheng Zhu! Zicheng is a PDRA on our @mapphub project, where he works partially in our team and partially within a colleague's team. A big part of what he's been working on within our team is understanding the relationship between processing... https://t.co/9Ijconngzl
parameters, porosity and mechanical properties of #3DPrinted parts, including some in-situ testing we hope to be able to report on soon! He's also been working on some industry-funded project work, has been involved in some of our Outreach activities, and is also a new dad!
Before I sign off for the day, let me say a big thank you to all of the previous staff, PhD researchers, Masters, Undergrad and placement students who've worked in our team over the past few years - too many to name, but all appreciated!
That's all from me for today, so I'll be back tomorrow and the rest of the week to tell you all about #3DPrinting, and how the processes and materials interact to make beautiful parts... and what happens when we get it wrong!
Hi everyone, I'm back to talk some more about #3DPrinting. First up take a look at the thread I made for @scottishscicomm's global science day back in March, to give you a quick whiz through what 3D Printing is and why it matters: https://t.co/W5hO8lujgH
Then in a while I'd like to tell you about some of my favourite applications and processes, before we start getting into details about the science behind the processes and materials. As always let me know if you have questions or things you'd like me to talk about!
So let's start talking about #3DPrinting processes. Almost all of them work from the same principle of building parts one layer at a time. (We're starting to see a few processes which have moved away from the layered approach, but I'll talk a little about that later.) https://t.co/TzJ7aIeamP
Now for many years we couldn't all agree on how to categorise the processes. Should we focus on the type of material they use, the method used to join the layers, the properties of the parts, or something else entirely? After a lot of discussions (arguments?) a group of...
process categories was defined, based on how we join our layers together. I'm not going to go through all of these now, but you can see a list in Section 2.2 of the ISO/ASTM standard here: https://t.co/5IxiDOPX2x
I'll highlight a few example processes shortly, but what's quite interesting is the way in which processes have changed over time. The very first commercial processes had one thing in common, which is that they all used some form of single-point 'scanning' to produce the layers.
You can think of this as being similar to colouring a picture - everywhere you want to colour, your pencil must touch the page. While this is an *effective* way of colouring, it's also pretty inefficient, and that's one reason why the early 3D Printing processes were a bit slow! https://t.co/b0Z3qXl2jP
It became quite clear that having to scan, melt, or deposit each pixel of material in a layer individually wouldn't allow for the speed increases that were needed for many applications, and people started to look at ways to cover more area in a shorted time.
Quite a few processes sprang up where a layer was covered in a single 'pass' of a print-head, array of nozzles, or similar. This allowed for quicker printing of each layer, but also in some cases had benefits in terms of processability and consistency. https://t.co/SNd9HHRIce
From there it's a relatively quick stretch of the imagination to move towards producing the whole layer in a single 'flash', saving time per layer but with perhaps some added complexity to the overall process, or working to constantly 'grow' the parts without specific layers...
I'll be back in a short while to give you an idea of just some of the range of processes we've seen since 3D Printing started, many of which are great and some of which might be better categorised as 'interesting'... I'll probably leave you to decide which are which!
@John_Sevigny @KLeoPullin I agree! That's part of the fun of it for me, never knowing what will come up next!
@KLeoPullin @John_Sevigny @RealSexyCyborg I didn't, but I do now! Thank you for the tip! :)
Let's talk a little bit about #3DPrinting processes. The first to be commercialised was Stereolithography, which works by selectively curing cross-sections of a photo-curable resin using a laser. Laser Sintering (similar technique but using a powder rather than a resin) and...
Fused Deposition Modelling (which effectively 'draws' the layer by extruding molten material from a nozzle) came relatively soon after, with variations of each method still being used a lot today. But what about some of the other processes which have been important along the way?
One of my favourites when I first got into this was Z-corporation's 3D Printer range. They were the first people to enable full colour 3D Printing (OK, it was only surface colour but it was early days and quite exciting!). The process works by printing a binder onto a layer...
of powder and bonding the particles together. The parts were quite fragile and needed some post-processing in order to get good colour vibrancy, but opened up a lot of potential especially for more realistic-looking prototypes.
You can see some example parts in this video if you're interested in the sort of things these printers were making: https://t.co/7b4NHxiAo9
On similar lines, the Connex systems from Objet Geometries were pretty ground-breaking, as they introduced systems than that could process more than one build material at the same time. Multi-material printing opens up a lot more design possibilities, so this was big news!
These processes work by printing a UV-curable material, and following it with a UV lamp in order to cure it. Add more than one print-head, and you can print more than one build material. By 'grading' the amount of material you print across the build area, you can get a big...
change in properties. After quite a few years they also launched full-colour systems taking advantage of the same build process. You can see a video of the process here, complete with enigmatic background music: https://t.co/Zyifi15deU
One of the most exciting developments in recent years was Carbon 3D's Digital Light Synthesis technology (https://t.co/vQJrROLqob). Using UV light, a curable resin, and some clever chemistry, they 'grow' a part continuously, helping to eliminate some of the issues often found...
at the boundaries between discrete layers. Although there are still downsides as with any process, lot of process developments have been quite small iterations from where we were so it was quite exciting to get something genuinely a bit different!
To finish off today I thought I'd highlight a few processes you won't hear much about, but that always grabbed my attention for one reason or another! Early on I came across Rapid Freeze Prototyping. As you might guess, this involved... well... freezing stuff quickly!
In this process you'd deposit droplets of water out of a nozzle onto a sub-zero plate or environment, where they would quickly freeze. Subsequent droplets will freeze on top of the previous layers, and you'd keep building up the part until it was complete.
The most obvious application area was for making complex ice sculptures, but with potential for some casting or moulding applications. Of course the main disadvantage was that your part melting if you didn't use it quickly enough, but that was part of the charm for me!
And a couple of others that aren't really around any more, but that I had a soft spot for!
Araldite Digitalis (watch a video here - https://t.co/P7FDZPhLa7) used a system of micro-mechanical shutters to selective expose an entire cross-section of a photo-curable resin. This promised to be great for increasing process speed, with one other potentially big selling point
The system was designed by Huntsman (a chemical company), based around their in-depth knowledge of their materials. There are a lot of potential benefits to designing processes around materials rather than the other way round, but sadly we've not seen much from this process :(
And finally, a process I've always loved, despite it's flaws... Solid Ground Curing, from Israeli company Cubital, Inc. had more process steps than you could shake a stick at! The process worked by first creating a mask of toner on a glass plate, and applying a layer of resin...
onto a flat build platform. The mask would be positioned above it, and flashed with a UV lamp to harden the un-masked areas of resin. Any un-cured resin was vacuumed away, and molten wax spread over the build area to fill in the gaps. Of course that layer of wax was...
thicker than the intended layer thickness, and had to be milled back into a flat shape... Another quick cure of the resin layer, and the process started again. Far from the most efficient process ever created, but something about it always grabbed my attention!
That's about it from me for today, but if there are processes you specifically hoped I'd talk about please let me know! I'll be back tomorrow to talk about some of the less-popular bits of the 3D Printing process chain (and why they're super important!)...
which, almost as if I planned it that way, will lead nicely into how we go about research into materials and identifying the key things we need to consider! Talk to you all then :)
Hi everyone, in support of #ShutDownSTEM I won't be Tweeting about research today. You can read more about it here https://t.co/2XLpKFyhoP And if you want to spend some time reading about racial injustice, here are a few links to get you started:
Re-posting this from the other day as it has lots of good resources: https://t.co/pTxpfQ1C65
And a few relevant books and articles that are free to read at the moment: https://t.co/zudFdEOdfN
https://t.co/Vl6hsFESzl
https://t.co/LlVQag1bYm (free on Kindle for a limited time)
https://t.co/NHwf9hBtTe
https://t.co/BpQzFqTnJT
That's in no way an exhaustive list, so feel free to comment with others that you may have come across. I'll be back tomorrow with more #3DPrinting talk, so see you then.
[admin] "Cutting Through the Hype of 3D Printing" Extended conversation with @CandiceMajewski is out now - https://t.co/XtQRBdQSqu
Hi everyone! As promised I'm back with more to say about #3DPrinting. I think we all know there are bits of any subject that are the 'cool' bits and others which are important but much less exciting, and 3D Printing is no different! Most often when we talk about these...
processes, we focus on the manufacturing stage itself - the bit where we can watch the laser zipping around on the surface of the raw material, see the material being squeezed out of the nozzle, or various other visible aspects. https://t.co/bfjUKUlGjw
I'm the first to admit that those bits are fun (I'm still just as excited to watch our machines do their thing!) but in reality what happens before and after the manufacturing stage can have just as much of an impact on the quality of our parts.
My group is focused mostly on processes which use powdered polymers as feedstock, so I'll use that as an example. (I'll talk more about the processes in detail later on, but for now it's enough to know we're talking about polymer powders).
Now our powders have a lot of history before we even put them into our machines. The powder has to be manufactured, transported and stored somewhere in our lab, and we often need to sieve the powder before we use it. https://t.co/jGtWYrUx4P
We then pop it in the machine, deposit layers of powder onto the build platform and pre-heat the powder, all before we start the actual 3D Printing stage of the process!
Afterwards we need to allow the parts to cool, remove them from the machine, clean off any excess powder, and post-process them (often by bead-blasting). We'll also capture any un-used powder for use later on.
At every single one of those stages we can alter (sometimes deliberately but often unintentionally!) the properties of our material. This can also affect the final properties of our parts; that's not always a *bad* thing, but it's something we always need to be aware of.
So, I thought I'd talk a bit more about a few of these aspects throughout the day, and how they tie in with some of the research we've been doing. First of all I have some project presentations to mark though, so I'll be back in a bit to tell you that stuff!
I talked earlier about the different individual steps that make up an overall 3D Printing process chain. What's useful is that we can use those steps as a basis for defining where we need to focus our research, and where we think we can make the biggest improvements.
If we focus on the Laser Sintering process, where we selectively laser scan and melt the required cross-sections of our polymer powder, we can split the process into a couple of main stages.
First we need to deposit a nice smooth, well-packed, layer of powder onto a build platform, and then we need to make sure the powder melts and solidifies into a dense part. If we get either of these steps wrong, we can run into big issues!
For the powder deposition step, there are a lot of things that can help/hinder us. The machine itself has a part to play - how does it deliver the powder to the build area and how does it ensure even spreading (for example using a roller or a blade). We don't want potholes! https://t.co/T7KjBNfEus
The powder manufacturing method itself has a big effect too. Here's an image of one of the most 'standard' commercial materials, a Nylon-12, courtesy of one of our previous PhD students Alaa Almansoori. https://t.co/yZiqlR1tQg
Note that the particles are relatively smooth, with a 'potato'- like shape, and a combination of small and large particles. Although not a guarantee of success, these things can help to allow the powder to flow and pack nicely within the powder layer.
We can add small amounts of flow additives to help with this too, but we have to be careful - as with a lot of things in the world of 3D Printing, there's a compromise to be made - beyond a certain point the flow additives can start to have a negative effect on our properties..
But quite often, and depending on the manufacturing process for the powder itself, we may not get such nice smooth, consistent particles, as you can see in this image of some Polypropylene powder from another of our previous PhD students, Luke Fox. https://t.co/4YfrKW1cV2
When we end up with these more 'raggedy' (yes that's the technical term) powders we can still work with them but are less likely to end up with a nice dense layer of powder, putting a lot more pressure on the laser scanning part of the process to get the part quality we want.
Other things we have to watch out for are moisture uptake in our powders, which is very dependent on the specific material we're using, 'settling' of any flow additives and/or different-sized particles from the transit or storage of the powder, and any contaminants in our powder.
All of those considerations take place even before we start the build process itself, so what things do we have to look out for once we get started? I'll be back to give you an idea of the main things in a little while!
Before I finish for the day, let's have a quick think about what happens when we start the 'making' part of the process. At its most simple, we're 'zapping the powder with a laser to melt it into the relevant cross-section', but in reality it's a lot more complicated...
If we look at Nylon-12, the most common Laser Sintering polymer, there are a lot of things that make it really well-suited for the process. This chart from Mike Vasquez sums it up very nicely - x-axis is temperature, and y-axis is energy input/output. (https://t.co/dh8EIxx6ya) https://t.co/O03hqKllPG
If we look at the graph carefully, we can see a number of key aspects that really help with the process. As we heat up the material, we come to a fairly sharp melt peak (evidenced by a relatively sudden intake of energy without an increase in temperature).
This allows us to heat our powder quite close to its melt point before scanning with the laser, which as benefits in terms of processability. Heating further we can see a large 'Stable Sintering Region' - this is the temperature range in which we can keep heating the material...
without causing it to degrade - if we push it further into that region we'll see a drop in mechanical properties of the resultant parts. Where it gets *really* interesting is when we start to cool the material... The temperature at which it starts to crystallise and solidify...
is quite a bit below its melt temperature, which is probably the most exciting thing about it! This allows us to hold our un-sintered powder at a temperature *above* its crystallisation point, but below its melting point, meaning the areas which have been scanned and melted...
are also held above their crystallisation temperature. Effectively this means the scanned areas remain in a molten state throughout the whole build process, which allows for much better bonding between consecutive layers. Pretty cool, right?
It's probably no surprise to you that most polymers don't behave anywhere near this nicely! Many of them have much more complicated (annoying?) thermal profiles, and various other factors affect how well they can be processed.
Melt viscosity determines how long it will take to fuse two particles together nicely, as well as the accuracy of the parts themselves - too 'runny' and we'll get poorly defined geometries!
Surface tension also influences the way in which the particles will melt together, as does their physical size, and the rate (and consistency) with which we cool the parts will have a large effect on their final properties.
And of course some materials we're asked to try (not mentioning any collaborator names, but you probably know who you are), behave completely the opposite of every material we're used to using, which leads to a whole lot of head-scratching while we try to figure it out! https://t.co/G8vjbE5Idq
Really this means we've got plenty to keep us busy in terms of understanding how we can process more difficult materials. Sometimes it feels like the more we know, the more we realise we don't know, but I think that's all part of the fun of research!
All of which neatly brings me to the end of the day, and a good point to pick up on tomorrow, when I'll talk a bit about what happens once we remove our parts from the machine, and the ways in which we can characterise and understand their properties.
I'll also go into a little more detail on a few of the projects we're currently working on, so see you all then!
It's Friday! Well done on making it through another week, or if you work different shifts In hope you're doing OK so far 👍 As promised, I'm going to talk a bit this morning about what happens after we've built our parts, and how that affects their properties.
First up, let's think about the end of the Laser Sintering process. You can picture the end of the build as a bunch of parts (still molten), encased in a tub of relatively loose, warm, powder.
Polymers have pretty low thermal conductivity, meaning it takes a while for heat to dissipate through them - if left to cool naturally, parts at the centre of the build will take longer to cool that those at the surface or closer to the metal sides of the container.
Why do we care? Because the rate at which we let the parts cool will have an effect on how much they crystallise, which in turn has an effect on their mechanical properties.
If we have variation in cooling rates that translates into variation in part properties, we're potentially losing some of the repeatability we're trying so hard to get!
At this stage we also have to consider the effects of processing on the un-sintered powder surrounding the parts. We can quite easily recover most of this powder, but don't forget it's been held at a temperature close to its melt point for a long time by this point.
This leads to changes in the molecular weight of the powder, and to how well it can be processed in future builds. It's standard to mix this 'used' powder with fresh powder to help keep things working well, but beyond a certain point we'll start to have a big effect on...
'sinterability', part performance, and surface finish. Check out this work from the excellent folks in Louisville, who were the first to report on this: https://t.co/2WwXVM02kS and in particular this image of how these changes affect surface finish! https://t.co/2mf2VoyrB9
So what can we do to check on the quality and consistency of our parts? We know that processing parameters (eg energy input, temperatures, speeds) have a big impact on part quality, and we're starting to understand a lot more about this and how we can use it to make improvements.
Within our EPSRC Future Manufacturing Hub we're doing a lot of work looking at how we can help powder-based manufacturing processes (not just 3D Printing ones) reach their full potential. You can see more at @mapphub or https://t.co/Va04rgYI4L
One of our PDRAs, Zicheng Zhu, has been investigating the porosity of parts produced using High Speed Sintering. This process is similar to Laser Sintering but uses a combination of a printed ink and IR light to induce melting in the relevant areas of the powder layer.
This image, taken from micro-CT data, shows what we get when we put in a lot of energy into our parts - the dark areas are solid areas of the part, and the light blue are pores within the solid structure. (There's about 7% porosity by volume in this part). https://t.co/OfSFfcypL2
Now see what happens when we put a lot less energy into the parts - this part has about 32% porosity, and you can see how this porosity is aligned with the layers of the manufacturing process. (Excuse the picture quality, as I don't have the originals on this computer!) https://t.co/JR5kiqUN8T
Using this sort of analysis we can start to see which individual processing parameters have the biggest effect on the size, shape and distribution of our pores, and what effect these have on our mechanical properties.
By understanding these things better, we can start to work on making improvements to the systems themselves, with a view to gaining better control of the properties and repeatability of those properties, that we can achieve.
Keep an eye out for some upcoming publications on this as well as some super cool results from some in-situ testing, where Zicheng and out colleagues in Manchester scanned some parts while tensile testing them!
I've mentioned the effect of our processing parameters, but as it's a rainy Friday (at least here in Sheffield), perhaps you'd enjoy a quick look at what happens when we don't quite get it right... https://t.co/KWkvgr3QPj
Although we can take a good guess at some parameters (often through a combination of examining the material's thermal profile and comparing with parameter sets we already use for similar materials, sometimes it comes down to luck as to whether we get it on our first attempt!
As well as understanding how things work in our processes, we're also keen to make our parts work harder! By introducing extra functionality into them, we can start to add a lot of extra value.
I thought to end the week I'd talk you through how we go about this, using the example of some work we've done to investigate the inclusion of anti-bacterial functionality into Laser Sintered parts. You can read our recent paper on it here: https://t.co/xgiLyemo22 if you like.
This EPSRC-funded project involved bringing together people from engineering and micro-biological backgrounds, so big thanks to @microshep, @Bobatron, Tom Paterson and James Wingham!
Our aim was to introduce anti-bacterial properties into our parts, by incorporating a silver-based additive into one of our standard polymers. We chose nylon-12 because it's so easy to process, meaning we'd be reducing the likelihood of processing difficulties.
A project like this necessarily starts by us seeing whether we can actually process the part in our machine, or whether including the additive would cause us problems. These images might not look that exciting, but they represent getting over a key milestone! https://t.co/Wkx53isFU6
Next we want to see whether the additive has caused us any change in the mechanical properties of our parts compared with the base nylon-12 - thankfully we saw no difference between samples produced with and without the additive... https://t.co/qE4K6nTDuw
During this time @microshep also ran some tests using human cells, in order to make sure we weren't going to hurt human cells in our attempt to get rid of bacteria! Looking good so far, so we started seeing what would happen when we expose bacteria to our treated parts... and...
what we found was super interesting! Depending on the test conditions we used, our approach worked well, a bit, or not at all! From a research perspective that's given us lots more possible avenues to explore, which we'll hopefully get back to once our labs open up again.
Here's a nice (false colour) image from @bobatron, which I'm including because it's pretty awesome! https://t.co/SLhtye0r4P
We also tried out some other interesting things along the way, including using micro-CT scanning to look at how well our anti-microbial additive was dispersed throughout the parts we produced.
Check out this lovely micro-CT image from one of my PhD students, James Wingham! The grey areas is our base nylon-12 material, which makes up most of the part. The black areas are pores within the part, and if you look closely you'll also see some little white 'dots'. https://t.co/wEP7yZlCTQ
These are where our silver-based additive is found within the part! So from this one measurement we can get an idea of how porous our sample is, where that porosity is located, how big it is, what shape it is, *and* how well our additive is distributed throughout the part.
Like all good researchers, we love when we can get plenty of information all at the same time! Hopefully that's given you a bit of a flavour of some of the #3DPrinting research we're doing at the moment, but please ask if you have questions or would like more info on anything.
I'll finish off my week tomorrow by showing you a few of my favourite applications of 3D Printing, but for now I hope you all enjoy the rest of your Friday!
@Bobatron Whoops, sorry! Thanks to TOM for the image, and Bob for giving him bacteria... You're right, that does sound a *tiny* bit bad...
Edit on this Tweet - I forgot Tom is actually on Twitter @SciPaterson !
@SciPaterson You could always have this account for a week! You get to do a podcast and everything!
Back for one last chat about #3DPrinting! To finish the week I thought it would be fun to talk about some of my favourite applications that I've seen! Let's start with the final frontier... https://t.co/V8PSzmybHu
Space applications of AM have been talked about for quite a while; fixing things that are broken, creative solutions to things that go wrong up there, building space habitats, or even food for astronauts.
When this was first talked about, the big question was 'can we get 3D Printing to work in low gravity situations'? One of my favourite ever images, which I can't find the reference for, is this one of a 3D Printer turned on its side as an initial test of whether it might work... https://t.co/IF8lAZXlfU
Reader, it did! This was an extrusion-based machine, which was then tested on on the affectionately-named 'vomit comet', an aircraft following a specific profile to allow for a short time of weightlessness (see here for some more info - https://t.co/XUECyeaCGr)
Again it worked, and (to cut a long story short) we now have 3D Printing capabilities on the International Space Station! If you're interested you can read some of my thoughts about 3DP in Space in this article I wrote a while ago here: https://t.co/XuCEmPnKyc
Something else we've seen recently is a lot more TV shows and movies using 3D Printing to create complicated and/or futuristic designs. One of my favourites recently was Queen Ramonda's crown in Black Panther: https://t.co/Y5lh0qrYBR
To digress slightly, fashion has shown quite a lot of interest in 3D Printing (see this *amazing* dress worn by Dita Von Teese - https://t.co/OKY1EW4I8z), and if you Google* '3D Printed high heels' you'll find a heap of cool shoe designs *other search engines exist
Iris van Herpen (https://t.co/UykvxQ40Tr) is definitely someone to check out if 3D Printer fashion is your thing!
Many of the big sports companies have been exploring the use of 3D Printing in their footwear, although this is yet to become really mainstream, and we can see a lot of cool jewellery and headwear designs coming through as processes have become better (and in some cases cheaper).
But back to TV/movies... As well as just making fancy props, some companies have been really leading the way in terms of how they apply 3D Printing to movies. Years ago I watched a presentation by someone from @LegacyEffects, and I was blown away by pretty much all of it!
I remember an advert they'd worked on for... I want to say one of the Halo games..? as well as how they'd used 3D Printing to make alien teeth for the movie Cowboys vs. Aliens!
But what about people using 3D Printers in shows and movies themselves? I'll be honest, this one often leaves me conflicted! Once you know the ins and outs of how 3D Printing processes work, and what things they're suitable for, it's hard not to notice when shows get it wrong!
If you know me, it'll be no surprise that one of my favourite movie scenes is the one in Jurassic Park 3 when they've 3D Printed a raptor's voice box... They took a few liberties with some of the detail, but this scene gets replayed a *lot* in our house! https://t.co/DDEeHZYUXM
Small Soldiers is another favourite - who can forget watching those prototypes rise up out of a relatively realistic Stereolithography-type printer? 😃 https://t.co/JpizMvk8Ay
There are plenty of other movies featuring some 3D Printing, as well as bunch of TV shows - CSI, Batwoman, Westworld to name a few, and of course I'm always happy to argue about whether the Replicators in Star Trek count as 3D Printing!
Of course food is a big one that comes up - we've seen 3D Printed cheese, chocolate, plant-based steaks, sugar, and a (tenuous) 3D Printed pizza. Check out this example found by one of my students a few years ago! https://t.co/bLxMs93c13
I mentioned medical applications earlier this week, and that's likely to be a key area of continued growth for everything from surgical planning through to prosthetics and implants, and on to 3D Printed body parts.
Check out this lovely example of 3D Printing rehabilitation devices - https://t.co/8HjhwRNljy or this Ironman 3D Printed bionic hand - https://t.co/7SQm4VazT8
You can see a few examples of medical applications in this article I wrote for the 2019/20 UK Manufacturing Review (@ukmfgreview) - https://t.co/eZa6UTYuBa and I'd recommend @3DMedNet as a great source of info on this area.
There's lots more I could talk about, but it's nearly the end of my week on this account so I'll be signing off shortly. Catch me at @CandiceMajewski if you want to find out more about anything I've talked about this week.
Before I go, I'll leave you with a couple of my own personal examples of using 3DPrinting... First up, Blades of Chaos replicas for Cosplaying Kratos from God of War... https://t.co/Lwpwh4BVFp
And in person with the final result... Who said research interests can't overlap with other areas of our lives?! https://t.co/QxC2qSgdSq
And finally, I never like to leave without showing off my 3D Printed wedding flowers... Designed by Guy Bingham, produced on our Laser Sintering machine by @Rohilla, and carried by me at my wedding to Bret! Enjoy your weekend everyone! https://t.co/j0CEW1CFRU
[admin] thank you @CandiceMajewski for a wonderful week, we learnt a lot about 3D printing. give Candice a follow! Podcasts & more - https://t.co/XtQRBdQSqu https://t.co/41WraBzJy3
Patrick Spicer
[admin] "Squishy Nanomaterials & their Interactions with Surfaces" Welcome Patrick Spicer (@SoftMatterHackr ) https://t.co/Kv36HDAZfE
Hello to everyone, this is @SoftMatterHackr picking up the account for the week! I'll be talking about my colleagues' research, the ways commercial products can connect with fundamental research, and how the structure and #rheology of #softmatter affects so many things around us.
This week I'll introduce myself, go quickly through my roundabout research path, and then dive into telling you about our group and as many of my great colleagues (like Baldur here) as I can. Please add your own interests, questions, and suggestions as we go. https://t.co/2njnNvK5tx
I'll end today by saying how lucky I am to get to talk to you. Events of the last year lay bare how we must do better to protect each other. In industry, our safety slogan was: "Nothing we do is worth risking someone else's safety," and we must be aware of this every day.
Hi all! @SoftMatterHackr here. As promised, a bit of background on my path to research. The people in my life were critical to my experiences and I do everything I can to pay that back to those who might not get a chance to connect to science and research. https://t.co/hYlKJHWmYG
I was born in the US state of Delaware. It’s a tiny state but has a funny divide between its north and south. The north is urban, where the duPont chemical company and the University of Delaware were formed. https://t.co/gEDdYuNDMu
Southern Delaware is fairly rural by comparison, with chicken and corn farms everywhere. It also has great beaches that attract huge numbers of out-of-state tourists every summer. I grew up very close to the beach and was hugely influenced by my parents. https://t.co/8Bm17rAJSU
My father grew up quite poor but worked to become an accountant in the north, where he met my mom. He didn’t like working just for financial gain, so when Delaware created Community Colleges he left his corporate job to support education in the rural areas where we grew up.
Dad worked as a COBOL, FORTRAN, and RPG programmer, reporting on demographic and internal data for the college and region, and taught a number of courses over time. He taught me to code and exposed me to early modems and online games in the late 70s and early 80s.
My mom studied biology and was an amazing force, saving my life as a newborn. I had undiagnosed milk allergies that almost killed me. She was so angry at a doctor who dismissed her concerns she got more opinions and found someone who could supply infant formulas without milk. https://t.co/SXu6KzfeRd
I had a number of jobs, and even apprenticed with an industrial glassblower. This is 15yo me working on a quartz “boat” that held silicon wafers for etching into integrated circuits. The quartz melted at very high temperatures and was my first really viscous fluid system! https://t.co/Oh3tOiPFs0
I then got a summer job with the local plastics company run by a former duPont chemist who would employ anyone local who was college-bound. He talked me into studying chemical engineering at university. I was lucky to live in Delaware, where the state uni was a top ChE school.
Once at UD, I worked as a lab assistant with Prof. Jon Sharp’s group in the Chemical Oceanography department near my home and the beach. I was there three summers, moving from simple tasks to an independent research project funded by the US NSF REU program.
The group studied nutrient distributions in the Delaware Bay and River, using phytoplankton and other indicators of the health of the waterways. I worked on carbon levels in seawater, a measure of climate change. https://t.co/7gULKq4x3C
The REU program's purpose is getting Americans to go to grad school. It worked! Being around the grad students, seeing research in pure and applied forms, and benefiting the health of a region and industry, won me over.
My last college summer I wanted to do engineering, luckily Prof. Art Metzner referred me to an REU program at U. Cincinnati. There I met Prof. Sotiris Pratsinis, who assigned me to study sol-gel deposition of silica nanoparticles. At the end Sotiris offered me a PhD scholarship.
My PhD was on flocculation, where small particles aggregate in mixed fluids, enhancing settling and filtration. This is used to treat waste and drinking water, and my project was sponsored by a company to improve recovery of valuable enzymes produced by engineered bacteria. https://t.co/6jJiDrMXnR
I was the only student in my group working on colloids, everyone else studied aerosol nanoparticle production by high-temperature combustion, sponsored by the duPont Company, connecting me to industry and combined modelling and experiment used to understand material processes.
When I needed experimental equipment to quantify floc sizes and structure, my group infrastructure couldn't help with liquid studies. My supervisor didn’t have equipment funding but had travel money. He sent me to groups in Australia and the Netherlands to use their setups. https://t.co/x9o0aYdUgU
These trips really opened my mind to other countries and cultures, and imprinted on me the importance and power of collaboration. I’ve worked from the same playbook ever since.
My time in Australia had broader long-term benefits. Returning to Cincinnati I went on a blind date with a woman who was also just back from Australia. Our mutual amazement at the coincidence broke the ice: we married the year after. https://t.co/aGbN7rqSt0
18 years later I moved my whole family to Sydney to take the job I’m in now, working with colleagues like Rose and Graeme who were PhD students when I first visited! https://t.co/MfQU9o4woD
After finishing my PhD, I went to work for the Procter & Gamble Company in Cincinnati. Tomorrow I will touch on my experiences there doing a wide range of applied and fundamental research, with both industry and academic collaborators, and lots of nano!
[admin] "Squishy Nanomaterials & their Interactions with Surfaces" Listen to Patrick (@SoftMatterHackr ) talk about his science on podcast #62 https://t.co/Kv36HDAZfE
Hi, @SoftMatterHackr here again. This time a thread about my experience working in industry as an engineering researcher for the Procter & Gamble Company. P&G is a company started in Cincinnati that originally made soap and candles and is now a huge consumer products company. https://t.co/X9Vf4k3Xxl
I was hired into a group that acted as consultants for all of the product business units globally. Corporate Engineering was a scale-up consultancy, with strong knowledge about manufacturing products at a large scale (12 tons) but were developed on liter scales.
P&G makes a lot of things, and my group focused on complex fluids, materials with non-Newtonian rheology. This simply means that their viscosity can change depending on how fast they flow, because they have properties of both solids and liquids.
Cornstarch in water is a well-known non-Newtonian fluid, it thickens when deformed quickly. An opposite example is shampoo. If you measure the slow flow viscosity of shampoo it is nearly identical to honey. But if you make shampoo flow faster it gets thinner, or less viscous. https://t.co/SofKdQYQO9
Shear-thinning occurs as microscopic particle structures temporarily break down in the shampoo. Honey, on the other hand, stays just as thick when you move it quickly, so don’t try to wash your hair with straight honey: your hair will not last!
Complex fluids like shampoo are often water-based, but they can drastically change their flow properties when relatively small amounts of particles, surfactants, and/or polymers are added. Others: detergents, soaps, cosmetics, conditioners, shaving cream, mouthwash, toothpaste...
A key economic point is consumer products can be made, using mostly water and small amounts of additives, to feel rich, creamy, and pleasant. These aesthetics distinguish such products from fine chemicals and petrochemicals.
Petro- and fine chemicals are judged based on purity, while consumer products are judged on qualitative criteria like softness and qualitative criteria like the thickness of skin coatings. So knowledge of structures in complex fluids is very profitable.
So a specialist organization is needed to make these materials at large scales. If the the fluid changes its properties while it is being mixed, for example, it is much more unpredictable as there is often not a reliable theory of how these products behave in processes.
As a result, a lot of our work blended modeling and simulation with experimental studies of flow and structure of the products. One of my first projects with the company was studying how to make the wax crystals that are used to give shampoo a pearlescent appearance.
The optical effect occurs when lots of flat, plate-shaped crystals line up in layers in the shampoo and light scatters from their edges and centers with interference effects similar to what is seen with real pearls. https://t.co/SO99hYBMaK
After that I worked on a crystallization process forming nanoscale fibers to modify the rheology, or flow properties of beauty products. I noticed that melted droplets of these waxes could crystallize and repel their own solid phase, moving and producing "comet" particles. https://t.co/dfnZWhM4NT
Next two things happened that really affected my career direction. P&G started to get interested in nanotechnology. The US had funded the National Nanotechnology Initiative and everyone was excited by the potential of nanoparticles and other nanoscale systems. https://t.co/qOiwyiL0ba
P&G also realized they needed to look externally for some innovation. Big companies often can’t move fast enough to develop everything needed. Their new approach, called C&D or Connect & Develop, rather than R&D, meant partnering with others, say academics, to speed development. https://t.co/P34dYvDTNT
In my next thread I’ll tell you about my biggest nanotechnology project for P&G and, really, in my research career. The best part of the story is that it made my employer the most money by far, but also got me in trouble for the first time there...
Another post from @SoftMatterHackr here, this time about a nanoscience project we did while I worked at P&G. As with all of my projects, this was a collaboration, in this case with Dr. Matt Lynch and other colleagues at the company
The project originally began as a conversation Matt and I had about self-assembled systems, where molecules like surfactants form larger structures on their own, without additional guidance or templating.
We were originally interested in delivering anti-inflammatory drugs across the skin, and were considering liposomes as the delivery vehicle. Liposomes are simple lipid bilayers wrapped up into spheres, and were hoped to penetrate skin well enough to deliver the drug.
But, commercially, you must avoid infringing on other patents. This was hard with liposomes. At the time there were thousands of relevant patents we had to avoid. Despite this, the excitement about nanoscience drove us to look at soft nanoparticles like liposomes as a solution.
Fortunately, I’d just done a course on surfactant science with Prof. Stig Friberg at Clarkson U., and he’d talked about a new self-assembled particle: a cubosome. https://t.co/ZodlfZF1UE
Where liposomes form from relatively simple curved bilayers, cubosomes are dispersed particles of cubic liquid crystalline phase, where the bilayers are contorted into space-filling minimal surfaces like this: https://t.co/bDGszRdegO
When we checked, there were only four patents on cubosomes, so we felt there was a much better chance of creating something new with them. This is a nice example of patent maneuvering: we couldn’t patent cubosomes, but the key patent process could only make a few grams of them.
The existing patent mixed a lipid and water in the right proportions, forming an extremely viscous cubic phase, and then used ultrasonic treatment to blast the material into nanoparticles. This meant only small volumes could be made, as power was aimed into a small container.
Since we needed to make much larger quantities, we pursued a new approach. We treated the very viscous material as a solid, and reasoned that if we made a solution of it, then diluted it and precipitated the particles out, we could make nanoparticles with hardly any energy input.
Because our new process allowed us to make cubosomes on a large scale, we were able to patent it. https://t.co/n2YxqxOsox
Our team grew to include new employee Kristin Hayden and Janet Burns, who studied the phase behavior of the system and made critical cryo-TEM images of the particles to verify what we were making. https://t.co/DV4SxgjEDu
The project followed a normal path for a while, and we started testing the materials for use in a skin treatment. One of the steps is to ensure that it doesn’t irritate skin. We did this with the Skin Science Institute at U. Cincinnati with Dr Marty Visscher and Dr. Steven Hoath.
As part of the normal testing, Steve noticed something unique about cubic phase. Unlike occlusive treatments like petroleum jelly, that protect against drying but block exchange with the environment by skin, cubic phase kept the skin hydrated while still allowing skin transport.
Steve hypothesized that this could be used for a different purpose than we originally intended. At the time there was no skin treatment for premature babies to protect them against infection.
When we are born, we have a coating on our skin called a vernix, that is the remnant of the lipid template the body uses to form our stratum corneum layer. Premature babies can lack this because it hasn't finished forming and creating that skin barrier.
So when born prematurely, we often lack a barrier against infection and are very vulnerable until our skin fully develops. They proposed we adapt the cubosome product to treat premature babies. We loved the idea, but commercially it was not viable for the company.
Still, we persevered and worked with our internal tech transfer people to see about transferring the IP we’d created to Children’s Hospital in Cincinnati.This would allow them to develop a product, actually an artificial vernix, that could be applied to preemies as protection. https://t.co/AuK4T5dBND
So, the company made money by donating our patents, the University Hospital got to help the babies, and the state government used our example to announce new tech collaboration program support. Here's the Governor of Ohio, Bob Taft, with Matt and me on the day of announcement. https://t.co/IOvgYaedko
His photographer had a good sense of humor, as he carefully positioned me so that it looks like I am being immunized by a statue in the background. The statue is of Albert Sabin, developer of the live polio vaccine.
And now the trouble I got into: I gave a lot of talks after this happened, both to share our work and to increase our collaborations with academics. At one of them I mentioned that these cubosomes were nanoparticles. There was a journalist in the audience...
The journalist wrote that I said P&G products contained lots of nanoparticles. This is a big no-no for consumer product companies, as the public does not not like nano in their stuff. When I got back from the conference I got blasted by our PR people and had to help explain.
It was a good lesson about nano, that is still valid in many ways: doing nano will get you credit in science but can cause trouble in the commercial food or consumer space. (Nanomedicine people get away with it because they are trying to save lives and fight cancer!)
I'm almost done with my curation term. For my last thread I will bring you up to date and talk about what we're doing at UNSW in research and development!
OK, @SoftMatterHackr back again. I had a lot of fun over 15 years at P&G, but was interested in making a change, both to pursue my interests a bit more and to move my family somewhere unique. I was fortunate that a job had opened at UNSW Sydney, and moved us to Australia in 2012.
As you do, I recruited students for a while until I had built a core group of my first four PhD students: Dr. Haiqiao Wang, Dr. Jie Song, Dr. Prerna Dahiya, and Dr. Goldina Kwandou. https://t.co/GgJ12CENjP
Dr. Dahiya studied droplet coalescence, understanding how rheology can offset interfacial tension and form non-spherical droplet shapes, but also how the process of arrest can be used to build larger-scale structures. https://t.co/qMczUHg82L
Dr. Wang looked at cubosomes and similar particles, not as nanoparticles but as microparticles and she found a number of ways to produce particles with complex, controlled shapes as well as template them using polymerization processes. https://t.co/XYGiVvHmQR
Dr. Song developed a new microrheology technique to study non-Newtonian fluids made from nanocellulose dispersions and measured complex yielding transitions of the fluids using tiny bubbles as probes of mechanical properties. https://t.co/ClHu0CkBgo
Dr. Kwandou used a number of techniques to understand how biofilms form, and respond to novel treatments like cold plasma, showing that bacteria can be opportunistic and actually be preserved from thermal treatments because of structures formed by their dead brethren. https://t.co/Cc4jg3i9aO
These days my research group focuses on the topics discussed above as well as some new areas. I discussed one of these when I spoke on the podcast: thunderstorm asthma. https://t.co/S2yIjetyGO
Thunderstorm asthma is a unique but dangerous condition that is not fully understood. It is now thought to occur when storms draw grass pollens into thunderclouds, rupture the pollen, and disperse allergenic proteins, basically biological nanoparticles, into the population.
The resulting effect on people inhaling these particles has been to cause difficulty breathing and dangerous symptoms of asthma. What’s even more remarkable about the phenomenon is that many of the people experiencing the effects had no previous history of asthma.
We are collaborating with groups at U. Sydney, QUT, and UNSW to better map the mechanisms, using microfluidic channels to expose pollen to extreme conditions, simulate the experience in a thundercloud, and directly observe rupture and subsequent release of the allergens. https://t.co/D3r5EAOBb0
Our collaborators are using these particles to quantify the level of inflammatory response the particles cause to differentiate between different starting conditions. We hope this work will lead to enhanced prediction and warning of thunderstorm asthma conditions.
I hope this week has shown a bit of what we’ve done in the area of commercial and academic soft matter. I’m grateful to @MySci_PK for the chance to share it all and look forward to great future curators. Visit us at @SoftMatterHackr to discuss any of these topics. Bye for now! https://t.co/77kcHyp6PX
[admin] Thank you Patrick for teaching us about the squishy nanomaterials and their intereactions with surfaces. Do give @SoftMatterHackr a follow! Podcasts - https://t.co/Kv36HDAZfE https://t.co/GyQNQ4D6S3
Benjamin Eggleton
[admin] "Photons on a Chip" Welcome @ProfBenEggleton! Podcast interview - https://t.co/0hRHjxqD7a
It's Sunday morning in Sydney and it's a lovely day so I am going for a long walk with my dog - stay tuned
Obligatory photo of me, my dog and my mum to kick off the week. I’m looking forward to curating the content this week - stay tuned for (i) my journey; (ii) @SydneyNano highlights; (iii) @EggletonLab photonics and (iv) coping with covid19 perspectives https://t.co/3Lz9F6o2Ft
My first research project was on the topic of using optical fibres to remove wavefront aberrations induced by atmospheric turbulence to improve the performance of a stellar interferometer.- for imaging stars.
That was in 1992 and was in the early days of optical fibre technology. I like to say that at the end of this project I saw the light and decided to shift from astronomy to optical fibre research. I started by PhD in the Optical Fibre Technology Centre at the University of Sydney
My PhD was on Nonlinear fibre optics with a specific emphasis on solitons in optical fibres. I spent 6 months at Bell Labs in 1995 where I discovered a new class of soliton -the Bragg grating soliton. I graduated in 1997 and went back to Bell Labs as a postdoc.
From 1997 to December 2002 I was at Bell Labs, Lucent Technologies (then OFS) as a Postdoc, Member of Staff, Technical Manager and then Director. I was there during the telecom bubble & burst and then 9-11 and decided to come back to Sydney at the end of 2002.
In 2003 I started at @Sydney_Uni as a Professor in the School of Physics @sydney_physics as the founding Director of CUDOS, an ARC Centre of Excellene. Our mission was to create and develop a photonic chip - a cartoon schematic is shown here. https://t.co/0VFJpN77xS
The photonic chip is an integrated circuit that is thumbnail sized, incorporating components for generating, manipulating and detecting photons, the building blocks of light. We use lithography to print circuits -leveraging the enormous investment that has gone into silicon https://t.co/k6pACFVH8H
Photonic chips (photonic integrated circuits) can incorporate hundreds of components and can be used for advanced signal processing in telecommunicaitons, radar, sensing and quantum technologies. The feature sizes required to define the components is nanometre scale.
I wrote an article in the conversation on the topic of nanophotonics - https://t.co/pcZajDI65z with a great link to a short cartoon on photonic chip: https://t.co/pcZajDI65z
The CUDOS program finished in 2017 after 15 years and we were all ready to move on to the next exciting challenge. My research now focussed primarily on using photonics to sense the world around us - the air we breath, the electromagnetic environment, our health etc.
In 2016 Prof Justin Gooding and I established the NSW Smart Sensing Network @NSWsensing. Sensors, detect, diagnose, monitor and respond to the world around them allowing pre-emptive and predictive responses in a vast range of settings https://t.co/CsHxCCyiU4
The @NSWsensing brings together expertise in academia, industry and government to position New South Wales as a recognised global leader in smart sensing innovation.
My group @EggletonLab focus on creating and developing photonic sensors that can be incorporated on to chip-scale circuits. https://t.co/Yf8s7DDC8F
We use the amazing facilities and capabilities in the @SydneyNano Sydney Nanoscience Hub - to manufacture the photonic circuits using lithography https://t.co/0NoCCexDRx
In 2018 I was appointed as Director of the University of Sydney Nano Institute @SydneyNano - a multidisciplinary initiative that spans all areas of the Universities research (science, engineering, health and medicine, business, design, music, law, arts.. ) https://t.co/2qBclNKFvq
At @SydneyNano we like to say that the next giant leap is seriously small. I am going to discuss the @SydneyNano research later in the week https://t.co/5MNyHWhQJO
At @SydneyNano I am fortunate to work with a wonderful group of talented colleagues @all_isee Gunther Schmidt @wchrzanowski @OmidKavehei @jrrabeau Anita Ho-Baillie, and others https://t.co/bitRLhy8cB
My research group @EggletonLab is a fantastic team of scientists and engineers from all over the world - we are based in the @sydney_physics at @Sydney_Uni @Sydney_Science with laboratories in the @SydneyNano hub. We co-host the @NSWsensing and participate in @IPOS_Sydney. https://t.co/quiPVBhjpX
My group is working with @AusAirForce as part of the Jericho Smart Sensing Laboratory that we established in 2019. https://t.co/IazSRJCSXG
I am really pleased to collaborate with @DrCaraWrigley on the Jericho Smart Sensing Laboratory which brings together design innovation with high-end science to accelerate capability https://t.co/n3ELxjhVFG
Tomorrow I am going to tweet about @SydneyNano research - starting with our Grand Challenge projects https://t.co/Kie8Q32GIA
And just in case anyone was wondering - we are huge @SSFCRABBITOHS fans in the Eggleton household https://t.co/06fdLylJTS
Good morning from Sydney where it is raining and cold (for Sydney is 12 Celsius in the morning)
Today I am going to highlight some of the great work being done by my colleagues at @SydneyNano -particularly emphasizing the Sydney Nano Grand Challenge projects https://t.co/VVl0RpFfIU
Nano Solutions for Grand Challenges The Sydney Nano Grand Challenges are aimed at discovering ground-breaking solutions to the world’s greatest challenges that are of social, economic and scientific significance. This short movie is a great introduction: https://t.co/ThrcKlxImQ
Sydney Nano Grand Challenges are flagship programs of @SydneyNano and foster multidisciplinary collaboration amongst Faculties, while presenting opportunities for industry partnerships, commercialisation and outreach. https://t.co/MLjmFV2KFO
There are six (6) inaugural @sydneynano Grand Challenges spanning: material science, quantum science, nanomedicine, nanodevices, nanotoxicity and catalyst. Let me briefly review.
Advanced Capture of Water from the Atmosphere (ACWA) - aims to develop a low-cost method to capture enough water from the atmosphere to alleviate the effect of drought by providing water for consumption by humans and animals, and for irrigating plants. https://t.co/KzA1cD27OC
CO2 Zero - Using nanotechnology for carbon-neutral manufacturing - Aims to reduce CO2 emissions in manufacturing processes and converting CO2 into commercial products through nanocatalysis. https://t.co/7djCEoEgnZ
Nanorobotics for Health - Developing molecular nanorobots for health care - Building autonomous, programmable nanorobots to navigate through the body to detect and treat early disease. https://t.co/G56mIHrtYA
Computational Materials Discovery - Simulating new materials from a single atom to fully functioning devices using quantum computers, multiscale simulation and AI. https://t.co/HVkkYlFRjm
Safe-by-Design Nanotechnology -Assessing nanotoxicity for safe and sustainable nanotechnology - https://t.co/C3x9jEaOAD
Unlocking the neural interface - Delivering cures for neurological diseases - Rethinking the means of intervention into the human nervous system to make untreatable neurological diseases treatable, and to transform treatments into comprehensive cures. https://t.co/gLbPHub5o7
@sydneynano was launched in 2016 as the Australian Institute for Nanoscale Science and Technology (AINST) but that was such a mouthful we rebranded as the University of Sydney Nano Institute - Sydney Nano - watch the launch video: https://t.co/8xmRuvOaYy
Great start to the week with a @SydneyNano Distinguished seminar from Prof Kourosh Kalantar-Zadeh from @Unsw on “liquid based metals electronics and optics” https://t.co/A88y3M5Iiw
RT @SydneyNano: Thank you @K_KalantarZadeh for opening our eyes to the exciting world of liquid metals at the @SydneyNano distinguished lec…
The University of Sydney Nano Institute: ready to embrace the future https://t.co/fJB6Mm0bQH
RT @all_isee: This week @ProfBenEggleton Director of @SydneyNano @Sydney_Uni is the guest tweeter for @RealSci_Nano. Head over to follow hi…
Good morning, today I will tweet on nanophotonics research with highlights from my own group -@EggletonLab
Did you know that 2015 was the International Year of Light - https://t.co/tGgvwFsJq5
What is the International Year of Light? The International Year of Light and Light-Based Technologies (IYL 2015) was a global initiative adopted by the United Nations to raise awareness of how optical technologies promote sustainable development and provide solutions ..
My team at @SydneyNano is leading a research renaissance into chip-based control of light-sound interactions that could transform our 5G and broadband networks, satellite communications, sensor technology and defence industries https://t.co/1Wfz8uI8nA
A growing group of scientists is adapting Brillouin scattering to a new generation of integrated circuits for 5G and broadband networks, sensors, satellite communication, radar systems, and defense. https://t.co/fSW8E6xh29
In 2017, @EggletonLab demonstrated the transfer of light to acoustic information on a chip - a chip-based information recovery technique that eliminated the need for bulky processing systems. https://t.co/MdoNYiLRQq
Speed plus control in new computer chip: slowing down light to sound - we demonstrated a new memory chip design that allows us to temporarily slow down light to a manageable speed for better control of computer processing. @EggletonLab @SydneyNano https://t.co/lxSDK4NRq6
Light packets were successfully stored as high-pitch sound waves – about 1,000 times higher than ultrasound – in a wire on a microchip. Around 100-fold thinner than a human hair, tiny wires were designed to guide light waves as well as high-frequency sound waves, (hyper-sound). https://t.co/9A6P1Ri0dC
Computer chips are reaching their performance limits, the old idea of a delay line-based memory using sound waves is back. This time it’s not in bulky mercury tubes, but tiny light wires on a microchip that are capable of processing much more data. https://t.co/Ou7YqVsUzh
This new research shows all the characteristics of a light wave – that is, brightness, colour and phase – can be transferred to a hyper-sound wave, and by doing so can be buffered. https://t.co/lxSDK4NRq6 https://t.co/qnEr7l9GVX
Long-Lasting Phonons for Light Storage https://t.co/Dflubk4NXm
“So far, we’d only considered the possibility of manipulating information in the electrical domain, then in the optical domain, and now we can also imagine manipulating information in the acoustic, sound wave domain, It’s the next wave.” https://t.co/EfuOVpn9M7
There’s a big, if counterintuitive advantage to holding data in the acoustic rather than the optical domain: The speed of sound is about 100,000 times slower than the speed of light. https://t.co/gKGJIMjNxk
A tsunami holds its wave shape over very long distances across the ocean, retaining its power and ‘information’ far from its source. Such waves – whether a tsunami or a photonic packet of information – are known as ‘solitons’. https://t.co/HkuonhTRTk
This collaboration @sydneynano and @sutdsg manipulated a light wave, or photonic information, on a silicon chip that retains its overall 'shape'.“Solitons of this nature – so-called Bragg solitons – were first observed 20 years ago in optical fibres https://t.co/htcevy0r6U
“We were able to convincingly demonstrate Bragg soliton formation and fission because of the unique Bragg grating design and the ultra-silicon-rich nitride material platform (USRN) we used. This platform prevents loss of information which has compromised previous demonstrations. https://t.co/rjOgFW4Day
Our discovery of Brillouin scattering on chip was so exciting that we started a new conference on this topic - Workshop on OptoMechanics and Brillouin scattering: fundamentals, Applications and Technologies (WOMBAT), every 2 years -1st was Sydney in 2015 https://t.co/k4OH902CC6 https://t.co/Z59OaxZgDA
Wombats are short-legged, muscular quadrupedal marsupials that are native to Australia. No wombats were injured in the making of this conference. https://t.co/bXd8Y0qsoT
In 2017 WOMBAT was held in Besancon, France https://t.co/xvmIBFP8SD
In 2019 WOMBAT was held in Tel Aviv, Israel https://t.co/egtSgNZYPe https://t.co/thSdBl8NIU
And in 2021 it will be held in Erlangen, Germany. https://t.co/kQRJYqCC0S https://t.co/YYepT4s54T
CMOS-Compatible Bragg Solitons - researchers based in Australia and Singapore have shown how to manipulate Bragg solitons on a CMOS chip which could help speed up future telecommunications networks. https://t.co/ylxAIcbHru https://t.co/750YWAAFRx
this is a really cool animation of a photonic chip - how it works and what it does: https://t.co/J1ZYKORZeb
@SydneyNano has a youtube channel where you can see some great short movies and animations that showcase the great research being done at @Sydney_Uni in nanoscience and nanotechnology https://t.co/XibQOOjexT
Let’s take a tour through the @SydneyNano building and the @EggletonLab laboratories and then the beautiful @Sydney_Uni Campus
My office https://t.co/hWMpZb2oz7
Lovely meeting space where I have lunch and the foyer - it’s pretty quiet today https://t.co/HTYBZ9I2t4
800 square meters of clean room space with loads of high end lithography equipment for Nanophotonics, quantum technology and other Nanodevices https://t.co/v2j6jTwyxT
Enter in to the @EggletonLab to see our fantastic Laboratories and equipment - it’s lunch time so it’s quiet https://t.co/qDNcfoxNs6
Our supercool cryo for low temperature photonics experiment - we can get to 1 kelvin https://t.co/fJURKa7g17
This is the supercool Jericho smart sensing lab - these experiments are all at room temperature but it’s still supercool https://t.co/fxQmm8DtSB
And the @Sydney_Uni campus is pretty quiet but is lovely as always https://t.co/omY58wCMkB
Good morning - a beautiful day in Sydney. Today I am going to tweet some good news stories about nano research with some emphasis on @SydneyNano
New material created to clean up fossil fuel industry A/Prof Jun Huang from @Eng_IT_Sydney and @SydneyNano has created a new material that has the potential to reduce CO2 emissions released during the refinement process of crude oil by up to 28 percent https://t.co/wJeZIgk0nv
Scientists unlock low-cost material to shape light for industry - Crystal materials used in solar cells can manipulate laser light with potential application in telecommunications, medical diagnostics and consumer electronics @SydneyChemistry @SydneyNano https://t.co/ZXdB74Fx25
Photonic chips have huge potential for the future of computers and telecommunications. Physicists have now developed hybrid architecture to overcome some of the engineering hurdles facing this technology. @SydneyNano @sydney_physics https://t.co/BqiPkAzCb9
Foundational step towards a quantum internet Quantum engineers show that atoms held in optical cavities - tiny boxes to hold light - could be foundational to the creation of a quantum internet - published in Nature. @QuantumJB @sydney_physics @SydneyNano https://t.co/UcsTik1Zvv
Ultra-precision nano-sensor could detect iron disorders https://t.co/nm7SdWrJww
Powerful breakthroughs by Sydney Science women https://t.co/QQYzQ3Eg6e
Nanoscale neural network developed with Japan and US researchers https://t.co/iTABfD6zIn
Developing DNA ‘origami’ technology to prevent blood clotting https://t.co/zASBSR1Elc
Let’s have a closer look at Photonic chip technology being developed at the @EggletonLab @SydneyNano @sydney_physics @IPOS_Sydney - here we see a 6 inch silicon wafer, the chip scale device (under microscope) and the chip integrated into PCB. https://t.co/wK4Foe0OWD
This is the probe station where we can probe the electrical and optical properties of the Photonic chip technology before packaging. https://t.co/ukvAw1AkXl
Middle of the week photo of a happy dog https://t.co/yJcIKuHuiY
A new law in laser physics could make eye surgery simpler https://t.co/fqalT7rXE6
Beautiful evening at @Sydney_Uni https://t.co/FO3xmFD9Zr
https://t.co/htOE6KMerp
[admin] "Photons on a Chip" podcast episode #64 with @ProfBenEggleton is out now -https://t.co/0hRHjxqD7a
One of the most beautiful roads on the @Sydney_Uni campus https://t.co/MAd0BcLBWh
What are some of the big challenges facing nanoscience? I would be interested in hearing from others.
There are many outstanding Nanoscience Institutes around the world - @SydneyNano is connected with many of them - this is our map - who are we missing? https://t.co/GRVQere3JP
@SydneyNano has established some great links with theb top nano institutes in North America, Europe and Asia
@SydneyNano is very pleased to partner with Waterloo Institute of Technology in Canada @WINano
@SydneyNano has established links with Bar Ilan's Institute for Nanotechnology and Advanced Materials (BINA) in Israel @BarIlanU https://t.co/YLfCQanOFH
@Sydneynano has established a successful MOU and student exchange with Pusan National University -- College of Nanoscience and Nanotechnology in the Republic of Korea https://t.co/S3Cv99bu04
@SydneyNano has established some great links with the leading nanoscience institutes in Delhi - here we are in Bangalore at the IIS and in Delhi at IIT. https://t.co/MaxxlMO6O8
I was thrilled to visit @EPFL_en earlier this year - hosted by Prof Luc Thevenaz https://t.co/VfebZOXNJr
We look forward to future collaborations with the University of Queensland's Australian Institute for Bioengineering and Nanotechnology @AIBNatUQ - here I am with AIBN Director Prof Alan Rowan @AlanRowan4 https://t.co/5XNiHREMP1
Yonsei University in Seoul has an impressive Institute for nanomedicine we visited in 2019 @YONSEISnW @SydneyNano https://t.co/UJrFGtoY2m
RT @RealSci_Nano: There are many outstanding Nanoscience Institutes around the world - @SydneyNano is connected with many of them - this is…
Beautiful aftenooon in Sydney - my last tweet from this account https://t.co/S4IGLzoMRV
[admin] Thank you @ProfBenEggleton for a wonderful week of nanoscience. Do give him a follow! Podcasts ft. Benjamin - https://t.co/0hRHjxqD7a https://t.co/8ti8NoQtGy
Haley Harrison
[admin] "Sending Boron Nitride Nanotubes to Space" Please welcome Haley Harrison @__Stellaaaar Podcast #65 ft. Haley speaking about her science -https://t.co/mtbg91vDhW
Good morning everybody!!! It’s hot in NC and I am preparing to travel tonight or in the AM to head to work. 😃
GM I’m Haley and I am studying nanoscience at the Joint School of nanoscience and nanoengineering (JSNN). This school joins North Carolina Agricultural and Technical University (NC A&T) and the University of North Carolina at Greensboro (UNC-G).
RT @AstroKatie: Wondering how cloth masks work to help prevent the spread of coronavirus? Here’s a nice video by @DrJoeHanson for @okaytobe…
RT @AstroKatie: Masks aren’t 100% perfect protection, of course — especially if you’re up close with someone or in a closed space for an ex…
During my week here I’d like to first talk about how I got into nanoscience and why I chose a joint program. There are so many benefits and collaborations to be made in programs like ours. Then I want to talk about the Materials Research Society at JSNN and what our mission is.
I will follow that up with an introduction to boron nitride, boron nitride nanotubes, why they’re cool and what I do in that space. Then I’ll o into some info on aerogels because they are so fun and deserve so much more respect as a material Lol
Unfortunately, I’m not in a lab that has the aerogel making capability, so I will try to find some old videos or use some open source on YouTube to share. I’m looking for a simple, easy and safe aerogel formula for teaching kids so if you have any ideas.... shoot them my way!
Good morning all!! What are we setting out to accomplish today?
I am working in a completely new lab space with new materials and a new polymer. For me, the first thing to do is read the literature. Pick a starting point. What about you?
Ok I have a moment to talk about my journey. So I started out my “academic journey” studying music performance and I specialized in piano and flute performance. That didn’t work out (financial) so I changed my major to physics.
It makes a lot of sense why when you understand that music and physics students spend a lot of time working to perfect their art. Lol
So, that went well but I really felt isolated and I didn’t like how theoretical physics felt. I just could not wrap my head around a lot of the concepts and it was draining. (At the time I didn’t realize there was an entire experimental physics field where I would fit.)
Nanoscience at its core is a physics phenomena. So, as a senior physics student I took a nanotechnology course and I was introduced to microscopy and spectroscopy as fundamental techniques for exploring nanoscale phenomena.
So when it was time for me to graduate I knew I wanted to go to graduate school. I just didn’t know what to study but I knew I wanted it to be nano related. I studied earth science and GIS and my research focused on surface chemistry during my master’s.
One of the first things I did during my PhD was tackle a side project working with fluorinated solvents. The reason this is especially challenging is these solvents are very volatile and they don’t really play well with others. https://t.co/gb1R3XxavL
Well lucky me. Boron nitride nano materials also don’t play well with others. Working in this system with very dense very volatile solvents trying to make boron nitride go into them you had to be prepared for failure. Lol
The left figure shows functionalized particles, clearly suspended to some degree in a non-ideal solvent system. The right is showing non functionalized particles. The middle was just something cool I found that we played with for a little while.
Even though this started out as chasing an idea my PhD advisor had during his post doc, it turned out to be a pretty awesome way to “prove” we did something. Why? Surface modification of BN materials is very difficult but! There is no fluorine in boron nitride.
If we could figure out how to detect fluorine, further learn to detect other functional groups we would be able to support the hypothesis that our technique could work.
The B-N bond is very strong and stable and resists chemical treatments as well as thermal oxidation. BNNT has been shown to be stable in air up to 900* C and higher. Amazing. As purity increases these materials continue to show out!
Even though the BNNTs are strong, a lot of the harsh treatments that work end up destroying the boron nitride tubes. So when people just mix them into composites or other materials, they make them perform worse. (We 👀 at mechanical strength, thermal decomposition, dispersing etc
Brief redirect: if you know of a technique I can use to study the stabilization of non-spherical particles in solution... let me know. 😂😌 people keep asking me to tell them. Idk. (I took this before I got a bad DLS measurement. I tried surfactants. No luck!) https://t.co/citANCv8lD
Unfortunately I can’t show you my beautiful lab because I’m not going with COVID. But I will direct you to our website. https://t.co/k5MtlaEra1
@NotHF Ooohhh I’ll look into it. Thanks
[admin] "sending boron nitride nanotubes to space" Haley, @__Stellaaaar, goes deeper into her scientific journey so far and her research experience on #66 podcast https://t.co/mtbg91vDhW
RT @realscientists: [admin] "sending boron nitride nanotubes to space" This week's @RealSci_Nano curator - Haley, @__Stellaaaar, goes dee…
Hey everybody! I am doing my favorite thing: sonication. But recently I’ve been tasked with other processes that don’t require sonication 😩😩 learning new things is hard. https://t.co/t1dxux1Wr1
In nanoscience, sonication is a powerful tool for dispersing nano materials. Sonochemistry is another area of research I have interests in, where the sonic energy can be used to perform chemical processes. This has been big for the environmental chemists and engineers.
This is a probe sonicator, so high frequency (ultrasonic) pulses are sent through the liquid system via a vibrating probe tip. When this happens powerful bubbles collapse and recollapse inside the liquid system. This mechanical process can be used to separate materials
Particles* i mean. Also, during ultrasonication, free radicals are created that can react with your system if you want. These radicals are short lived so the chemistry is very complex.
Currently just sonicating nano particles in a solvent. I tend to use non reactive solvents to sonicate because you don’t always want to induce a chemical reaction when sonicating.
@sassyscience_ Sonication is essential for our TEM prep!
@carlosromvil Yes! It is so complex but there are so many untapped ways to explore. Glad to hear it!
@MaterialsDan The methods are often left out, it takes work and I still have to explain to people how I use controlled sonication, I’m not just beating up the material. There is an end goal! Lol
So in conclusion, the reason we care about boron nitride is because of the high thermal stability, the radiation shielding capability, piezoelectric capabilities, and the ability to bring multi functionality to composites and other space technologies.
The opportunities are literally endless. Ohh! I can’t believe I forgot about the low density. These materials are very light weight (nano) so when you incorporate them into other marerials, for example a thermal shielding material, it will reduce the weight of the composite.
When we’re going to space we want to reduce weight in a few ways. One way is structurally, by reducing the mass of the vehicle or its electronic components. That means there is more mass available for payloads!!! The fun stuff.
RT @ProfRachelGaN: @MySci_PK @RealSci_Nano (There is no magic, only science - or in this case technology - which I do not yet undertand!)
RT @ProfRachelGaN: It was great to chat with @RealSci_Nano last year about my research last year - and now the podcast has magically turned…
RT @MySci_PK: Are you a materials/nano researcher? Do you want to talk about your work and feature on our podcasts? Do you want to take o…
@jjmcv it would be a very expensive thing to use to kill roaches lol
@labjg I’m not sure, actually. Would be interesting to find out.
Ok I am signing off! I hope to come back soon when I’m back at school and free to share all my research. But please follow me on my main account @__Stellaaaar in the meantime! https://t.co/6xlk0suvBh
[admin] Thank you Haley for a wonderful week of science! Podcasts ft. Haley - https://t.co/mtbg91vDhW https://t.co/6R5L0h1E2h
Sean Allen
[admin] "Nanotaxies for Fighting Cancer" Welcome Sean! Podcast #67 ft. @dishpodcast -https://t.co/HLGMvTdBy1
Hi Everyone! My name is Sean and I study nano materials for use as drug delivery vehicles! Specifically, I like using them to deliver stuff to immune cells (super specifically, to help immune cells fight cancer!)
My plan for the week! Sunday - What got me started in science and how I got here Monday - Cancer and the immune system Tuesday - Why use nanoparticles for drug delivery? Wednesday - Nanoparticles vs cancer: clinical examples
Thursday - Nanoparticles vs cancer: beyond drug delivery Friday - Nanoparticles: uptake and shape Saturday - Nanoparticles and immunomodulation
Does any of this stuff interest y’all? Let me know if you’re looking forward to a particular day, or if there is anything you’d like me to talk about specifically! I love chatting about the #ImmuneSystem #CancerResearch and #nanoparticle stuff!
I live on the west coast of the USA, so it is solidly past midnight now — I’ll start my first legitimate discussion when I wake up tomorrow! It’ll mainly be about my path to becoming a scientist, but I’ll be peppering science in along the way to keep it interesting!
I guess I’ll mention now though that my main twitter handle is @DishPodcast, which is to say I handle the social media for the podcast I co-host. The podcast is science-comedy, and though it is NSFW, I’m going to be keeping everything very SFW here! So no worries!
Nothing like sleeping in a little on the weekends! But now I’m up and ready to #scicomm ! Today is a little autobiographical...
Introducing myself again: I’m Sean! I’m a postdoctoral scholar working in the Nel and Meng labs at UCLA. I research cancer immunotherapy through the use of nanoparticles as drug delivery vehicles! ...what does that mean? I’ll get into it tomorrow!
But also like, how did I get here? What’s going on? Whose house is this? Well to tell you all the truth, I’ve wanted to be a scientist since I was in middle school.
Ya see, in middle school my dad gave me a book called "Engines of Creation," which wikipedia helpfully reminds me is about nanotechnology. Now, I can't speak to how well the book holds up, because I don't remember much about it besides it making nano-stuff sound very cool
To be honest, my first idea of nanotechnology was little "nanobots" swimming around fixing stuff in your cells or something. They looked something like this in my brain: https://t.co/3mtUxmGbtG
This makes me think of the movie The Fantastic Voyage where some folks shrink down inside a ship to go... blast a blood clot maybe? Along the way stuff happens, including getting attacked by antibodies n stuff. Very cool! https://t.co/RaYCIq1nTy
@GayRollerCEng You're going to be anger-learning some stuff! These are two kinds of nanoparticles I made during my phd, for example https://t.co/h8UPI6jhti
Also reminds me of that ep of The Magic School Bus where Arnold swallows them. I'm getting a little off track but whatever. https://t.co/qWHnh5sfLh
@GayRollerCEng Work in progress Although, tbf, "DNA Origami" nanoparticles seem like they can do pretty fancy stuff and have things kind of like arms and "computation". Not *technically* my specific area of research, but it seems pretty cool
Okay okay, BUT nanotech wasn't the only thing on my middle school mind! I had also learned another intriguing fact... that cancer cells are **immortal** https://t.co/bqL1WJ9WAZ
"Now things are starting to come together," said my middle school brain. Could I use nanobots (not really a thing...) to apply whatever immortality trick cancer cells have (more complicated than that...) to ALL my cells and make ME immortal?! "Obviously yes."
Also, my grandmother was suffering from arthritis and I was not a fan, so like, toss arthritis on the pile of things to deal with. ✅Nanobots ✅Immortality ✅Arthritis "I'll have this done by age 30"
Ah, youth. Well I'm 33 now folks (had a birthday recently!), and while I have not made nanobots, have not affected immortality upon myself or others, and have not cured arthritis, I *have* learned a lot of stuff! I promise.
I'm curious what other scientists and science enthusiasts remember about their inspirations for science endeavors. Are they as silly as mine? Hit me up and let's chat about them!
So how did I actually go about becoming a scientist though? Well, I went and got an undergrad degree @UCBerkeley, which was fun! Going in, I planned to get a degree in both biology and materials science, because I figured that nanobots must be made out of materials... right?
There are people who study nanomaterials from a materials science perspective (hats off to you folks!) -- but maybe 2 years in I realized that that was not really the direction I was hoping it was. So I dropped materials science! It's okay everyone, I'm still alive!
A brief digression for those of you in college or in high school or whatever -- if you can, try to go to your classes. Haha. I distinctly remember being miserable in organic chemistry class. 8 am, which was so doable in high school, became a nightmare time for learning in college
I remember thinking to myself, many times, "I'm going to be a biologist, why do I need to know what a Steglich esterification is?" Years and years later, as I was doing polymer chemistry and drawing out reactions, I wished I had actually remembered some of that stuff.
You never know what might be useful later in life! Anyway, so I got my B.A. in molecular cell biology (immunology emphasis), and knew I wanted a PhD. But I also had a feeling like I needed more research experience -- I hadn't done any in undergrad.
So I got my masters degree @SFSU in @LauraBurrusSFSU's lab! The lab works on WNT signaling, particularly during development. In my case I was looking at a protein called wntless, and what happens in the developing chicken neural tube when you 'knock it down' with siRNA.
That's a lot of words. Basically, WNT is a protein (well, a family of proteins) that gets sent out as a signal from one cell to another nearby cell. It is important in a lot of different situations! One situation is helping pattern the future parts of your spinal cord!
There is a protein that seems to be important for getting WNT properly shoved out of the first cell, so it can go signaling -- wntless (because if you get rid of it, you'll be wnt-less... Get it?) I won't belabor the point too much, except to say that dev bio is really amazing!
It was an interesting experience studying something a little further away from my undergrad studies (and middle school ideas). But it was also an extremely useful experience. If I'm being honest, I was a pretty crummy scientist for the majority of my masters degree!
I think I learned and matured a lot during that MS though, which really prepped me to hit the ground running when I went to do my PhD. For folks outside the US, btw, an masters before a PhD in bio isn't all that common -- I think PhDs in the US take longer to compensate for that
So then I went and got my PhD @NorthwesternU in @ProfScottBME's lab! I was accepted into the @IBiSatNU, which is an interdisciplinary biology program. 'Interdisciplinary' sounded particularly attractive to me, because I felt like I wanted to try mixing a lot of stuff.
One of the great things about my PhD program was rotations. During the first year, we basically got to try out three labs. I tried out a chemistry lab (MRI probes), a dry computational lab (so many research topics), and... a nanoparticle lab! They were all great labs!
It was hard, though, for me to resist the pull of the nano. Not to mention Dr. Scott's lab was brand new, and I'd be among the first students in the lab, helping to physically set it up from the ground floor. It seemed like an interesting opportunity!
I had a great time! PhD programs have a well deserved reputation for being mental (and often physical) meat grinders that really negatively affect PhD students. This is something that needs to be changed. While it was not my experience, I was lucky (and extremely privileged).
Work by @PhD_Balance to candidly discuss the issues graduate students face, including the need for mental health support, is a vital beginning. But there needs to be institutional support to move this forward! If this topic is interesting to people, check out @PhD_Balance!
Anyway, I'm going to talk a lot about my PhD work in the coming week, so I'll fast forward through to say... I did it! I got my PhD in 2019! And now I've been working as a postdoctoral scholar @UCLA for a little over a year!
RT @PhD_Balance: @RealSci_Nano Thanks so much for the mention! And this actually is spot on for our #PhDStrongerTogether topic for this wee…
Whew well that was a lot of autobiographical stuff! If you're hanging out on this Sunday and want something to do, drop in here and say hi! Are you interested in nanoscience? Cancer research? Immunology? Let me know! Have any questions? I mean, let's do this thing!
I hope everyone is having the best possible Monday you can! I'm definitely someone that gets hit pretty hard by the start of the week... Anyway, today is going to actually take a couple steps away from nanoscience to lay some groundwork on biology things!
Specifically, I'd like to talk about cancer and the immune system! This is going to take a good amount of talking, because both cancer and the immune system are very complex *separately*, and mixing them together makes it all pretty confusing!
Okay so first of all, cancer is a pretty big term that covers things ranging from 'liquid' cancers in your blood to solid cancer in, say, your breast. Cancer can range in how aggressive their growth and metastasis is, can range in how many mutations they accumulate, etc etc!
There are cancers that are intimately related to your immune system because they arise from the same (or related) progenitors -- cancers like lymphomas and leukemias. But most my knowledge is related to solid tumors and how the immune system interfaces with them.
The immune system is around to do a lot of work, but one of the jobs we know it best for is keeping us safe from enemies. Those enemies aren't only 'foreign' things like bacteria and viruses, but 'domestic' enemies like misbehaving cells.
There are a lot of things that can make a cell behave weirdly (including things like bacterial infections and viruses, but other stuff too, like mutations/genetic damage). Immune cells and neighboring cells are on the look out for cells being weird. They're on the lookout!
So, for a cell to develop into cancer, there are a lot of hurdles to overcome, including avoiding this surveillance. A lot of cells get stopped in this process, so with cancer we are often seeing the 'ones that make it' or the 'ones that slip through the cracks'.
When a cell is acting weird, there are a lot of ways that other cells can tell that something is going on. Cells stick stuff on their surface to help let other cells know what their inner workings are like!
Some proteins are signals other cells *expect* to see, like an "everything is OK" signal -- if it is missing, other cells can get suspicious Some proteins are signals that something is wrong -- so if you have that signal other cells get worried.
Our cells also have a protein called MHC I. MHC I is a protein that we stick little bits of other proteins on, almost like a 'sampler' dish of what proteins we're making inside our cell. Most of the time we're just making normal, everyday proteins encoded in our genome!
But what about when we're infected with a VIRUS? When that happens, some (or a lot) of the proteins we're making are viral proteins because it is hijacking our machinery! Well if the MHC system is still working, we'll end up slipping a chunk of virus protein on our surface!
This can help let your immune system know that something naughty is going down. So MHC I is something most of our cells keep updating, to show what they've been making lately! This is important for cancer!
Cancer cells often have accumulated some mutations (how many mutations can vary pretty widely!). Some of those mutations change the actual amino acid sequence of proteins the cancer cells are making (changing that sequence sometimes changes the protein function).
Well, those parts of the changed proteins *might* be recognizable to your immune system as a 'foreign' protein if it is slapped on MHC I and put on the cancer cell surface!
These are called *neoantigens* Neo because they're new! The cancer just made them through mutation! Antigens because that is what we call chunks of stuff (often protein chunks) that your immune system can recognize and mount a response to (typically adaptive).
So cancer making these neoantigens is thought to be an important way that your body can mount an immune response against cancer -- they're little signals that your immune system can recognize that the cancer is something other than a regular cell in your body.
But if it were that easy, we wouldn't be dealing with cancer in the clinic -- our immune systems would have this handled. Now, the immune system probably takes care of a lot of stuff before it ever makes it to cancer levels, but clearly we are still dealing with cancer today.
That is because cancer is SO TRICKY. There are MANY ways that cancer is able to avoid the immune system. Different cancers have a tendency to rely on different methods of immune evasion, but they can probably use more than one! Gah!
Examples! Cytotoxic T cells are a kind of immune cell that are very good at killing cancer cells when they bump into them and recognize them. So cancer solution #1 -- don't let the T cells into the tumor. Seriously! Some cancers set up a "T cell exclusion zone!" https://t.co/SlW4ZV5GCG
If someone is interested I can talk about some of the molecular mechanisms behind the set up of this zone (so tricky....), but for now I'm going to keep it relatively easy to digest and light on the details.
Anyway, I mentioned that cytotoxic T cells are dangerous for cancer cells. They are also important for fighting off viruses -- they kill infected cells so that the virus can't keep hijacking the cellular factory.
Cytotoxic T cells need to have an "off switch" though (all immune responses do) because you want to be able to wind things down when the infection is over! There are several different off switches that can tell cytotoxic T cells to calm down.
One example is the kynurenine/IDO pathway. This is a situation where cells (often other immune cells) can toss out a signal into the extracellular environment that says "okay y'all, let's calm down this immune situation!". T cells respond to this signal by... calming down
When you look inside a tumor. you typically see more than JUST cancer cells. You might see some of the 'normal' cells that were living in the neighborhood before the cancer cells started wrecking things. But in a lot of cases you'll actually see other immune cells
...What the heck are those immune cells doing! Get to work killing that cancer! But unfortunately, these immune cells have been reprogrammed in the tumor microenvironment (neighborhood) to behave a certain way.
These are pretty recognizable names in the immune cell world! Macrophages! Neutrophils! Dendritic Cells! Often these cells do a great job with things like launching off inflammatory signals and eating up bacteria. But in tumors, they often do the opposite!
They often become kynurenine factories, pumping out that signal to turn off other immune cells. They can help in setting up that T cell exclusion zone I mentioned earlier! They can even put out growth signals to help egg on the cancer cells https://t.co/eIpScuhrHr
Cancer cells can exploit another "off switch" that T cells have -- a kind of 'secret handshake' that tells the T cells that they bumped into a good cell and need to chill out. This GIF, except not cool ⬇️⬇️⬇️ https://t.co/ALljYWJeOi
The handshake happens when certain proteins on the surface of T cells bump into and bind with proteins on the surface of other cells (sometimes cancer cells, but it can also be on those other pesky naughty immune cells that aren't doing their proper job!)
Examples of this handshake can be: T cell | Other cell PD-1 PD-L1 CTLA-4 B7-1/2 LAG-3 MHC II TIM-3 Galectin-9 and more! https://t.co/aPd8WuOzfC
When a T cell gets this handshake, it'll basically back off and cool down and won't kill the cancer cell. That is a significant bummer!
Tumors can also be 'immunologically cold' in that they haven't set off enough immune alarm bells to have their neoantigens recognized as foreign. Some cancers, by the way, hide their neoantigens by choosing to hide their MHC I! Man they are naughty.
So the thing is, even if you have a tumor where: the cancer cells have neoantigens AND you got to see them AND T cells aren't excluded AND they aren't burned out from kynurenine some cancer cells can just shake the T cell's protein-hands and prevent them from doing their jobs! https://t.co/L87iisFlzZ
A relatively recent trend in cancer treatments has been ~Immunotherapy~ Cancer immunotherapy is about giving treatments with the goal of helping the immune system overcome all these tricky hurdles that cancer can toss up!
An example of cancer immunotherapy success has been the use of blocking antibodies to physically keep T cells and cancer cells from "shaking hands". So an antibody that targets PD-1, for example, binds to that PD-1 on the T cell and prevents it from hooking up with PD-L1
This has been called immune checkpoint blockade -- the handshake is an 'immune checkpoint' because it can turn off your T cells, and these cool antibodies can *block(ade)* that processs! Nice!
Now, for what is likely to be a TON of different reasons, immune checkpoint blockade works very well in some people and some cancers, and like... not at all in others. This is truly a bummer. But that just means we need to keep working on it!
In broad strokes, one very plausible reason why immune checkpoint blockade doesn't work in everyone is that it really only deals with *one* of the immune evasion tricks cancers have up their sleeves.
For example: If the tumor is super T cell-excluded, does it matter if you block a handshake that couldn't happen in the first place? This reminds me of that thing about a tree falling in the woods with no one around.
Or another example: If a cancer isn't mutated all that much and doesn't have many neoantigens, T cells might never care enough about them to even notice them. So what could would immune checkpoint blockade do?
There are other possibilities -- antibodies are smaller than cells and viruses, but are pretty big for proteins and *definitely* big compared to "small molecule drugs" like most chemotherapeutics. Do they have any issues getting into solid tumors?
Antibodies are also pretty bioactive -- they are proteins our body produces itself and are recognized by a lot of our cells. When we use them as a treatment, do they sometimes get taken up or bound up before they get a chance to do their jobs?
It is hard to make universal statements when it comes to cancer! But it certainly is the case that immune checkpoint blockade antibodies have helped many people fight their cancers -- these treatments are getting approved for more and more types of cancer each year.
I think what is becoming clear (or at least, I'm advocating for this view) is that cancer immunotherapy is something that can work, but we probably need to combine multiple tactics so that cancer can't evade its way around our therapies!
Some of this will boil down to a more 'personalized' look at the details of a patient's cancer. Does the cancer seem like it has a lot of neoantigens? Maybe immune checkpoint blockade will work without any help! If not, maybe we need to add something to the mix to help out...
I'll get into this more (tomorrow? I think?) but this is one place I think nanoparticles can help out -- they can help deliver more than one treatment to the same spot (i.e. the tumor) Nano can help us make a combo punch to knock the cancer out!
!!! Yeah! But some of the indicator lights work the way ours do, and other work the reverse — they’re always supposed to be on, and if they turn off, that means something is wrong. https://t.co/YjrnRLZaC4
The "nano" part of RealSci_Nano is coming into play today! Mainly, I want to go over the multiple answers to the question "why use nanoparticles for drug delivery?" https://t.co/h37h6GKoZt
Well what's the alternative, smarty-pants?! Just kidding. Many many of the drugs that are administered to you are "small molecules" and are typically under a nanometer in size.
I have a little figure here that my friend and colleague Molly Frey made (from the Scott Lab, @NorthwesternU) at my request. These are 5 reasons I think nanoparticles are useful for drug delivery! The little yellow shape is a small molecule drug, the green ball is a nanoparticle https://t.co/kILolY3xG6
Okay so let's do (a) first! Some small molecules don't really like floating around in water! If you put them in water, they tend to clump together and 'precipitate out'.
Some small molecules get chemically modified to improve their water solubility, or get mixed with some stuff to try to help keep the drug from precipitating, like PEG400 (a polymer) or DMSO (an organic solvent).
But another option is to put the small molecule into nanoparticles! Nanoparticles (here I'm thinking particularly about those that are amphiphilic, like lipid or polymer nanoparticles) have areas where they like water and areas where they don't.
For example, you might make a nanoparticle out of some polymer. This polymer has two parts to it -- a 'green' part that likes water and a 'red' part that doesn't (this, by the way, would be called an amphiphilic diblock copolymer) https://t.co/T7HjsosKlk
If you toss some of that polymer into water, the 'red' part that hates water will naturally try to hide from the water! This forces the polymer to 'self-assemble' with other polymer strands into little shapes where the 'red' is inside and the 'green' is outside, facing the water https://t.co/RQYcy6grDz
That's a nanoparticle! I mean, depending on how big the polymer is (and other factors) it doesn't HAVE to be a nanoparticle -- it could be a microparticle instead. And it doesn't HAVE to form a ball with the red sitting in the center like that -- other shapes are possible! https://t.co/Rd7V9W5sKZ
But the main point here is nanoparticles can have areas inside them that are 'red', that are *hydrophobic*. Those areas can be very accommodating and welcoming for hydrophobic small molecule drugs that reeaaally don't want to be hanging out in water.
So, one big benefit of nanoparticles is you can make small molecule drug formulations with hydrophobic drugs that are otherwise really hard to make soluble! This improvement to solubility often also improves the *stability* of the drug in water -- it won't precipitate out easily
@NotHF lol, I think they're nanoparticles so long as they're small enough 😉
Whew, that was all for (a). What about (b)? https://t.co/1UtcZtL40p
An important consideration when drugs are designed and tested is their pharmacokinetics -- covering criteria like their Absorption Distribution Metabolism Excretion Metabolism is chemical alteration of the drug in your body, which can change how well it works!
Sometimes that is a good change, but often it is a 'breaking down' process that makes the drug not work anymore. In some cases, putting your small molecule inside of a nanoparticle can help protect it from enzymes or other molecules that might damage your cargo
@NotHF You fancy transition metal NP folks...
@NotHF Luckily I never used a bath that hot, but making my polymer amphiphiles relied on plenty of "why does no one know why we do this reaction this way?"
@NotHF I'm mostly making mesoporous silica nanoparticles right now and it is certainly... different, let's say... from self assembled polymer nanoparticles. Yeah. Different!
So let's see... (a) Nanoparticles can help with solubility (b) Nanoparticles can protect small molecule cargo from degradation (c)? What's going on there? https://t.co/fWmYrnNQx6
Okay so the idea behind (c) has to do with the distribution of your small molecule -- where does it go in your body and what cells end up getting treated? In most cases I can think of, when you take a drug it is intended to get to work on some subset of your cells
But when you take a drug orally or by an IV injection or something, a lot of the time it ends up going to a LOT of places in your body, and can end up affecting MANY kinds of cells. Not all of those cells were really your 'target' cells.
Sometimes that is fine, but sometimes that can cause damage and/or 'off-target' effects. Doxorubicin is a chemotherapy drug that can cause really serious heart toxicity (Why are you hitting the heart like that dox? Go fight the cancer!!)
Well one *potential* benefit of nanoparticles is you can change where in the body the drug goes and what cells are more or less likely to take them up. There's probably a lot of reasons why this change happens.
First of all, small molecules are... smaller than nanoparticles. So they can squeeze out of small holes in your body than nanoparticles and end up in different spots in different amounts than a nanoparticle would!
Small molecules can also *stick* to stuff and have that seriously impact where they go. For example, there are proteins in your blood like serum albumin -- some drugs LOVE sticking to serum albumin and can get dragged into different parts of the body.
I don't, by the way, mean to say that nanoparticles themselves can't be sticky. Not only *can* nanoparticles be sticky, they almost ALWAYS are sticky. The 'stickiness' of nanoparticles is something scientists often try to modulate to change blood circulation time
This is turning into a bit of a tangent, but in any case, the surface of your nanoparticle definitely impacts what organs it goes to and what cells gobble them up. And you can do some engineering to try to control that (some)!
Surface charge can impact where nanoparticles go! Surface hydrophobicity (and curvature, and other stuff) can impact 'protein adsorption', or basically proteins in your body glomming onto the nanoparticle. Nanoparticle SHAPE can impact cell uptake!
Yeah! Little nanostars can get taken up by different cells preferentially compared to little nanoworms, or nanodiscs, or nanofootballs, and so on! There's a lot of thoughts as to *why* this happens... maybe we can go into that tangent sometime...
But anyway, you can also try to really specifically get your nanoparticle taken up by particular cells using *targeting stuff* attached to the surface of your nanoparticles. These could be antibodies, DNA aptamers, sugars, or seriously a ton of other things people have tried.
I am *personally* a bit of a targeting skeptic -- I think it takes a lot of careful work and design to make a nanoparticle that *helped* by the addition of a targeting moiety more than it is *hurt* by the added complexity. But I love being proved wrong!
So (c) is basically that you can engineer nanoparticles to change where your drug goes, compared to if it were floating around your body willy-nilly. In the example of doxorubicin, which I mentioned earlier, a nanoparticle-delivered version of dox reduced heart toxicity!
It is broadly safe to use than 'free' dox, but has its own, *different* toxicities! lol Nanoparticles aren't always going to take something from 'dangerous' to 'completely safe'! Sometimes it'll be 'dangerous' to 'less dangerous' Or 'dangerous' to 'differently dangerous' 🤣
(a) Improve solubility (b) Prevent degradation (c) Targeting/Distribution stuff (d) ? https://t.co/8EVdUkCTuh
Sometimes one drug just isn't enough to do the trick! Maybe you want to be able to deliver 2-3 drugs all at once to The Same Spot or Cell If you just swallow 2 drugs, they might have very different pharmacokinetics! One could end up in the lungs while the other is in the liver!
Nanoparticles can act like a delivery vehicle, or like an Uber or Taxi, for your group of drugs. That one nanoparticle could be loaded up with all three drugs, in the ratio you want them delivered, and sent off!
You can't guarantee it'll go EXACTLY where you want it to, but all the passengers will go there together! And they'll arrive at the same time -- in some situations that might be *biologically* a very important thing to accomplish!
(a) Solubility (b) Protection (c) Distribution (d) Multiple Passengers! (e) ? https://t.co/giJVBOMMmW
(e) Reflects a reality of drug discovery, which is that sometimes you find a molecule that can have the biological effect you want (like inhibiting some pesky enzyme), but the molecule itself isn't suitable for use in the body
That can be for any of the ADME reasons -- maybe this molecule doesn't get distributed well in your body, or maybe it breaks down too fast or isn't soluble. So you probably want to tinker around with it! Add a chemical group here or there, maybe attach a PEG polymer on it
OR... You can put it in a nanoparticle and get around the engineering issues on the nanoparticle level!
Basically, instead of finding a drug that works and then trying to further engineer it (at the risk of making it less functional or much more expensive), engineer that stuff on the nanoparticle level instead!
Nanoparticles can add an extra layer of engineering on a drug formulation. That can mean more complexity and cost, but it can also mean more flexibility and can potentially open up more areas of the 'drug space' that were previously too challenging to use in vivo
[admin] "Nanotaxies for Fighting Cancer" Extended conversation with @DishPodcast where Sean goes into the details of his scientific journey and more is out now https://t.co/HLGMvTdBy1
Today I'm going to talk about nanoparticles that are *currently* approved for clinical use in the fight against cancer. That's right! There are nanoparticle treatments in the clinic right now and have been for years!
Right off the bat let me say that there is a periodically updated review/survey of the clinical approval of nanoparticle treatments by @Aaron_Anselmo and @SMitragotri and I read it every time it comes out because it is *chef kiss* https://t.co/vQ7hMJWbrc
I'm pretty sure the first nano-drug to get approved by the FDA was Doxil, which I actually mentioned yesterday. I say "pretty sure" because I'm a scientist and I've gotten really used to hedging any 'fact' I say, but I feel pretty good about this one.
A pretty fun 2012 review of Doxil's history was written by Dr. Yechezkel Barenholz, one of the inventors. It is a pretty good mix of biographical insights, historical recollections, and experimental details. https://t.co/4ipRlDNMvV
Doxil is a PEGylated liposomal formulation of doxorubicin -- I *definitely* talked about doxorubicin yesterday. It is a chemotherapeutic drug that can really kill the crap out of cancer cells (but can hurt other cells too if you aren't careful).
The 'liposomal' part of a liposomal formulation means that the nanoparticle that was used was a little lipid bilayer sphere. It has a pretty similar bilayer to the one that cells do (with less lipid variety and fewer proteins and stuff shoved in there, typically).
PEGylated means the liposome has some PEG polymer attached to its surface. PEG stands for poly(ethylene glycol), so it is a polymer made up of ethylene glycol units. PEG has a reputation for helping to extend the circulation time of stuff you toss into the bloodstream
Part of the reason is thought to involve the prevention of protein adsorption onto nanoparticles (or drugs, you can PEGylate drugs). Proteins sometimes stick to stuff! PEG can just physically get in the way, like those noodle hats you can wear to enforce social distancing https://t.co/kZUJjjV1cU
The size of the PEG and how much of it you attach to your nanoparticle is thought to affect its ability to do its job. Out of all the little lipids making up my liposomes, I typically have ~3% of them have PEG attached I use PEG that is ~45 ethylene glycols long
Anyway the PEGylation is thought to help the nanoparticle float around longer in the blood without getting glommed onto by a bunch of proteins and cleared out really quick by your liver. PEGylation is not without some issues!
First of all, some people have anti-PEG antibodies in their blood -- including people who have never been treated with a drug that has PEG in it. Some evidence suggests that having anti-PEG antibodies means you clear out PEGylated nanoparticles faster than someone without them
That SUCKS. Stupid anti-PEG antibodies. Anyway. A second issue is that PEG might help some with protein adsorption and stuff, but it DEFINITELY does not STOP all protein adsorption. Proteins still adsorb onto PEGylated nanoparticles.
So some people are working on other kinds of polymers that could someday replace PEG to try to get around these two issues. Best of luck, folks! Some of the contenders are zwitterionic polymers. PEG is cheap and works fairly well, so it'll be tough to replace.
@Felgraf_Physics One of these upcoming days this week I'm going to go into the uses of nanoparticles to fight cancer that *aren't* drug delivery-based -- a lot of the approvals historically have been drug delivery focused, but nanoparticles can do a LOT of stuff...
Wow wait, I was talking about Doxil and then I got side tracked by PEG. Sorry folks! Anyway, the PEGylation of Doxil was definitely important for its success, but so was the process for getting the doxorubicin INSIDE the liposome
Liposomes are little bubbles with water inside and outside the bubble, and a thin bilayer of lipid in between. Some hydrophobic drugs occasionally get loaded into the lipid bilayer (this is not a trivial thing to do, you can potentially disrupt that bilayer).
When you want to load hydrophilic stuff into a liposome, one way to do it is to simply form that lipid bubble AROUND the cargo you're trying to load! So now the drug is floating around inside the bubble!
This is not typically a very high efficiency process. Generally, a lot of the 'space' when you're forming liposomes is *outside* the bubble, so a lot of your drug never gets encapsulated in the first place! Bummer!
Small molecules can also potentially diffuse across the lipid bilayer of the liposome, meaning you can leak your drug out over time. Also a bummer!
But that isn't to say it can't work! It is just that this kind of cargo loading has some difficulties associated with it.
Anyway, 'regular old' loading wasn't working very well for doxorubicin. So they used a different kind of loading, one that is called 'remote loading'. In remote loading you make your liposomes, then add your cargo drug *to the outside* of those liposomes.
"Wait Sean" you might say "If the drug is outside of the liposome, how do you load it in?" That's a great question, person on twitter! You let the drug diffuse into the liposome down its concentration gradient.
Now, of course, if you reach an equilibrium then you really haven't done any better than 'regular old' loading. But with remote loading you have a cool trick -- your liposomes aren't empty, they're actually already loaded with a *trapping agent*
The trapping agent is something that associates with your drug cargo and *traps it* inside the liposome, such that the drug cannot diffuse back out. Your liposome becomes a drug trap! Once the drug checks in, it can't check out (for a while, anyway). https://t.co/BUSXxaWbwy
Remote loading can drive realllly high encapsulation efficiencies, like 90% -- which means out of all the drug you put into the mix with liposomes, nearly all of the drug ends up inside your little nanobubbles.
The 'trapping' part can also help reduce the leakiness, so you don't prematurely lose your drug en route to the cancer! One downside of remote loading is that it does not work for all compounds.
Based on the trapping agents currently used, you need a compound that is a weak acid or a weak base. The compound also needs to be able to diffuse through the lipid bilayer of the liposome!
Ah also, it is nice if the compound is fairly water soluble, so you can mix a good amount of it with the liposomes. Not *too* water soluble because then it might not make it through the membrane! Given all the rules, it is maybe impressive that any drug qualifies.
But several do! Including doxorubicin! Doxil was approved by the FDA in 1995, so it has been 25 years! Wow! Sometimes nanotech sounds very futuristic and there is an idea like "ah, the technology isn't here yet, but maybe someday". 25 years!
A majority of the FDA-approved nanoparticles used for treating cancer are liposomal formulations. Liposomes have been around for a while and a lot of people have become pretty comfortable producing them at a large enough scale to be used clinically.
That doesn't mean that liposomes are the *best* (or only) option! Personally, as a person who used polymersomes during my PhD, I sometimes feel the urge to list downsides of liposomes (replace all the lipids with polymer in a liposome and you get a polymersome)
But liposomes have really paved the path to clinical acceptance for a lot of other nanodelivery vehicles that are currently in clinical trials, so I can't get TOO mad at liposomes!
I want to highlight two FDA-approved formulations that AREN'T liposomes, though! They are: Abraxane and NBTXR3
Abraxane was approved in 2005, 10 years after Doxil! To me, it is a particularly weird nano-formulation because it is the chemo drug (paclitaxel) attached to a protein (albumin) But hey, it is nano-sized and delivers a drug that helps fight lung , breast, and pancreatic cancer!
Blah, I said NBTXR3 was FDA-approved a couple of tweets ago -- sorry everyone, it is NOT FDA approved. NBTXR3 has been CE approved in Europe (for marketing/commercialization), which is still a nice big step for them!
But what is NBTXR3 anyway? It is a Hafnium oxide nanoparticle that you can zap with radiation and it will help kill tumors. Hafnium is an element on the periodic table that completely flew under my radar. There are many cool nanoparticles you can make out of metal oxides though!
So personally, my work in based on using nanoparticles as little delivery vehicles to help drugs get into tumors. But that is not even close to the only way nanoparticles can be used to fight cancer! NOT EVEN CLOSE PPL
Nanoparticles are currently being investigated (and some are FDA-approved) for help in *diagnosing and locating* cancer! "Definity" and "SonoVue" are examples of nanoparticles that are FDA or EMA approved for ultrasound enhancement of different cancers.
But there are a lot of ways that nanoparticles can improve cancer diagnosis and the location of tumors! Nanoparticles could potentially help both within the bodies of patients and outside the body as crucial ingredients in diagnostic tests!
One way nanoparticles can help is on the detection of biomarkers of cancer. For some types of cancer, we have found certain proteins elevated in the blood of people with that cancer, for example CA-125 for ovarian cancer and CEA for colorectal cancer.
One fight, by the way, that I am wholly unsuitable for, is whether a particular blood protein biomarker is *actually* a good biomarker for a particular cancer. Some biomarkers are not without controversy -- the validity of biomarkers is an important thing to establish!!
Anyway, there are several ways to try to tell if a specific peptide or protein you care about is floating around in your blood -- one way is a 'sandwich' assay using antibodies that are specific for that protein. Yum! https://t.co/8UPG0puIGu
But in all these assays, there is a limit for how little of your protein there can be before you can't "see" it anymore. That limit of detection is something that nanoscience can help improve! There are a lot of ways to do this, tbh.
One is to use quantum dots, which are nanoparticles that fluoresce when you shine a laser on them. And they fluoresce REALLY WELL. Being very bright has advantages, including really good detection ability at low protein amounts.
This could potentially mean that really small amounts of your cancer biomarker could be found -- maybe making it possible to diagnose cancers at earlier stages than we currently do!* *Again, VERY dependent on biomarkers being valid and meaningful!
But nanoparticles can also help in *collecting* those biomarker proteins in the first place! The other day I mentioned stuff about protein adsorption onto nanoparticles when those nanoparticles are floating around in your blood -- proteins love sticking to nanoparticles!
In that way, nanoparticles can kind of act like little protein "vacuums" while they float around inside you. So the idea is, pop some nanoparticles into your blood, wait a bit for proteins to stick, then take them back out. Shake off those lil proteins and look for biomarkers!
There are people researching how well this works as we speak! Here's some example papers on it! https://t.co/GXHfHr2Id1 https://t.co/qewrBVCJLk
It is early days still, but you could imagine a situation where nanoparticles are used to collect cancer biomarkers from your blood AND used to help quantify those biomarkers in a sandwich assay! Double nanoparticles!
Finding cancer using nanoparticles doesn't just need to be on the biomarker level. Nanoparticles can help image cancer within your body, including pesky metastases that can be hard to see otherwise!
Nanoparticles can be detected using lasers, ultrasound, MRI, PET scans, and probably a bunch more -- nanoscience folks are very creative!
So if you have a way to get nanoparticles to associate with cancer cells more than other cells, you can use them to help you locate tumors and metastases! There are several ways you can try to accomplish this, and there is a lot of preclinical work on figuring it out!
Nanoparticles can also be used to fight cancer on the treatment side without bothering to deliver drugs! Nanoparticles can be used to heat up tumors until they die, enhance x-ray based damage to tumors, or generate damaging reactive oxygen species.
Nanoparticles (and cells, for that matter) are so small that sometimes we don't think about them as 'real things'. We don't imagine them as having a physical body that physically bumps into cells and physically gets gobbled up. But they do! They're real!
And what that means is that the *shape* of nanoparticles can change how they interact with their environment, especially within your body! Nanoparticles can be on the bigger side or smaller side, they can be squishy or hard, and they can be spheres or worms or other shapes! https://t.co/71Z1Q5fa48
(Just look at the shapes in that figure, not all the other stuff about polymer design, blah blah). One of the ideas in that figure, by the way, is even with one type of polymer you can make different shaped and sized nanoparticles. But we aren't limited to just one polymer
You can make nanostars! (From Liebig et al 2019 RSC Advances, https://t.co/0LDo9AsBTT) https://t.co/49aHsI3v0f
Nanodiscs, nano deflated ball things (sometimes called stomatocytes), hard nanoballs, soft nanobubbles... https://t.co/oZ9F2ZzJpx
In varying their shape and size, you change where those nanoparticles can go in your body! For example, your kidneys can directly filter stuff out of your blood, but only if the stuff is below a certain size! (6-8 ish nanometers, but also depends on the electric charge!)
When you start to get pretty big in the nanoscale (like hundreds of nanometers in diameter), you start to have a hard time diffusing around in tissues. If you inject big nanoparticles under the skin, they'll have a hard time moving very far from where you injected them!
Above a certain size, your nanoparticles get very attractive to cells in your liver that help clear stuff out from the blood. Sometimes this isn't what you want to have happen, but there are also situations where you WANT to deliver something to the liver!
Stomatocytes by the way, in case anyone was curious. From Tu et al 2017 Angewandte Chemie ( https://t.co/7wOhXddIVI) https://t.co/lakwmM1N7G
There is some evidence that 'worm like' nanoparticles circulate in your blood for longer, maybe because they don't slip out through gaps in your blood vessels as easily, or maybe because some cells don't know how to eat them... Karabin et al 2018 Nat Comm https://t.co/y4Rp3e453r https://t.co/MhV65b6ayb
Look at those little wormy goobers! Some of those filomicelles may be 'nano' in their cross section, but end up being 'micro' in length!
There is some evidence that suggests that how 'curved' your nanoparticle is influences what kinds of proteins like to stick to it and what sorts of cells like to eat them! Having 'flatter' areas (like a disc vs a sphere) might also provide more surface area for cell interaction
I apologize for being AWOL today folks! Today, the last day for me, I just wanted to mention how well-suited nanoparticles are for affecting our immune systems (especially the innate)!
Many nanoparticles are not so different in size and shape from viruses! And innate immune cells love trying to eat viruses and other nano-sized stuff: cells like macrophages, neutrophils, dendritic cells, and monocytes love eating nanoparticles.
This is often, by the way, a detrimental thing. The immune system is so good at eating nanoparticles that it often prevents nanoparticles from getting to the cells you ACTUALLY wanted them to get to. ...unless the immune cells ARE the target! https://t.co/h2cN3Oio6c
There are actually a lot of good reasons why you might want innate immune cells to be your target for nano delivery (or other nano hijinks)
Maybe you want to deliver anti-inflammatory drugs to help reduce the perpetuation of pathological inflammation and to promote wound healing!
Maybe you want to deliver antigen and adjuvant to immune cells as a *vaccine*! Several COVID vaccine candidates are delivered in your body by nanoparticles!
Or on the flip side, maybe you want to deliver antigen and an immunosuppressant to try to build *tolerance*, like for diabetes or food allergies
[admin] Thank you Sean for a wonderful week of science. Do give @DishPodcast a follow. podcasts and more about Sean - https://t.co/HLGMvTdBy1
Jessica Boland
[admin] "Non-destructive Characterization of Nanomaterials" Please welcome @DrJessBoland. 👇listen to the podcast to know what is coming your way this week! https://t.co/4B3DDAN2Gm
Good morning! I'm @DrJessBoland and I am super excited to be looking after the @RealSci_Nano account! I hope you will join me to hear how #terahertz #radiation can help us look at cool #nanomaterials, how #nanotechnology can change society and enusring #accessibility in #STEM
First, let me introduce myself and give you a bit of insight into how I ended up playing with #lasers for a living in the beautiful realm of #nanotechnology and '#terahertz. https://t.co/m7BTfLRfCy
I started as a lecturer in functional materials and devices in @PSI_UoM and @UoM_EEE at the University of Manchester in October 2018 and lead a research group focusing on #terahertz characterisation of #electronic #nanomaterials https://t.co/5eWjb88qei
So a cheeky question for all the lovely #Scientist and #Engineer out there: did you always want to be in '#STEM ? Or did you have another dream career? And if you had to choose a different career now, what would you choose? I'll let you guess what my answers are! https://t.co/MOfHxHH8Oo
As you may have guessed, I didn't always want to be in #STEM but wanted to be a professional #ballerina. Unfortunately, I didn't grow tall enough so carried on exploring other things I enjoyed, which was mainly languages and maths, anything that involved problem solving!
I kept asking why we were learning things in #Maths maths, how was it useful in everyday life, how can we apply it to real life applications and realised that maybe #STEM was something to consider further.... I ended up choosing to study #physics at @UniofExeter and @UniofOxford https://t.co/zrcCNZWu3U
Since then my #research has become more and more applied and I have moved across to become an #ElectricalEngineer @OfficialUoM and am really loving it and looking forward to the future! But if I was to choose an alternative career, I would be …….a giraffe keeper !
One of my favourite things about working in #nanotechnology #spectroscopy and #electricalengineering is the variety of research directions you can pursue. I've worked on reflective displays or 'colour kindle' and plasmonics for microwave cloaking devices during my undergrad. https://t.co/omRtdOeqGI
And now am using #terahertz radiation to make devices for '#wireless communication, #healthcare imaging and non-destructive material characterisation! And who knows what will be next? https://t.co/zfLwLG4X3G
@DrJamesHallett @gns6w3 @FoliumOptics @FoliumOptics was the lovely group I got to do my internship with! They taught me all know about liquid crystals and reflective displays. There are still loads of applications for them, check out their health tags here: https://t.co/7AJRcaraeB
Welcome back everyone! Today we will be focusing on #terahertz radiation! What is it? Why is it awesome? How can it change society? So let's get started! #thzdoesitbetter
So what is #terahertz radiation? Terahertz radiation falls in between #microwave (think microwave ovens) and #infrared radiation (heat) in the electromagnetic spectrum. One terahertz (1 THz) is equal to one million million hertz (1^12 Hz). https://t.co/Z61D2KL9QG
The THz range encompasses light of frequencies from 100GHz up to 10THz and has wavelengths ranging from 30 microns to 3mm. It's energy range spans 0.4meV to 40meV ( heat energy from approx. -268 degrees Celsius to room temperature!) So what is exciting about this energy range?
So why is the #terahertz energy range interesting? Well..... the energy of several quasiparticles (phonons, excitons, magnons) fall in this range. If we shine terahertz radiation at a material, we can look at how these quasiparticles behave and also promote collective excitations https://t.co/W2rApYniRo
We can use terahertz radiation or #terahertz #spectroscopy to look at a material's optoelectronic properties. For example, we can look at its vibrational modes, how different carriers (electrons or electrons) move and scatter within the material and its magentisation dynamics.
Here is a great video from Hannah Joyce and Chiara Ciccarelli groups @Cambridge_Uni showing how a typical #terahertz #spectroscopy system works! https://t.co/6rG9lHSFnJ It is a powerful tool for non-contact, non-destructive #optoelectronic #material characterisation
So #terahertz radiation is useful for #material characterisation, but anything else? Of course! It has several uses from non-destructive medical imaging and security to revealing hidden secrets in art and looking at stellar dust in space! Let's look at a few of my favourite! https://t.co/PE6XGFXpiE
Starting with THz body scanners! Unlike #xray radiation, #THz is non-ionizing and harmless to humans. The key signatures of several chemical molecules also fall within the THz range, making it ideal for security screening. Here's an example of a body image from @Terasense_Inc https://t.co/vILflhgAeg
Not only can it identify hidden explosives, #THz imaging can also look at hidden layers in famous artwork. You can see lots of examples from Enrique Castro Camus' group at @CIOMexico https://t.co/VW6DNT50SG https://t.co/OcWUTkDl5b
Another cool application is in the #Automotive automotive industry. One of the key challenges is non-destructive evaluation of coating thickness on new shiny cars. @TeraView have recently demonstrated a THz sensor (TeraCota) with comparable performance to current approaches! https://t.co/Q6RwmPBkZ1
There is more! #THz also has applications in the #pharmaceutical industry. It can measure the porosity of tablets to improve quality inspection of new drugs. Check out the new tool from @THzCambridge and @TeraView for this inspection here: https://t.co/19Cke3Y43h
THz can also be used for in-vivo skin imaging. This image is from work by Emma MacPherson group @WarwickTHz (https://t.co/NrIzobws7x) . There is lots of ongoing research looking at #THz imaging to identify depth of skin burns, onset of diabetes foot and skin cancer. https://t.co/YhzrsfhZ8d
Finally, THz could provide ultrafast #wireless communication and carry up to 100 times more data! THz behaves differently though to #microwaves - so many groups are working on new components to make this possible. Check out recent from @opticsman et al: https://t.co/L4EQcf4rt7
P.S. This is just a few limited examples, there are so many awesome #researchers out there working in the field of #terahertz #science and #technology! If you are one of those lovely people, please shout out about your work and any of your examples to this thread. :D
[admin] "Non-destructive Electrical Characterization of Nanomaterials" ft. @DrJessBoland of @OfficialUoM on #70 Under the Microscope is out now This is an extended conversation with this week's curator- Jessica. https://t.co/mVgANDJ2fp
So yesterday, we were looking at #terahertz radiation and I hope I've convinced you that THz is cool and will make a difference in your lives. Today, I want to look at another aspect of my #research -#nanomaterials! So stay tuned to find out about #semiconductor nanowires
So why do we need #nanomaterials? You've heard about them in the news, but are they really revolutionary? Let's first think about how technology has changed during our lifetimes - the technology powering our devices has got smaller, faster and smarter, but is reaching a limit.. https://t.co/3gPjG0B8tL
This change is known as #MooresLaw, which predicts the number of #transistors on a chip doubles roughly every 2 years. At present, we have computing power equal to a mouse brain and are close to a human brain, but this trend is slowing down! Current Si transistors are only 7nm! https://t.co/HWNWjXluSD
We are already at the #nanometre length scale. At this length scale, #quantum effects start to come into play and we need to investigate #nanomaterials to work out how we can harness them @IBM have recently demonstrated 5nm #transistors using nanosheets https://t.co/KxvQk4mhW7
There is a lot of research into use of #nanomaterials for #device applications and there are already some examples. Below you can see some examples with a #solar cell, a #laser, and #transistor all made out of #nanowires and #nanoparticles for drug delivery! https://t.co/w1UnB2Dy1j
There are several advantages that #nanomaterials can offer. For the past few years, I've been looking at #semiconductor #nanowires as building blocks for devices. Nanowires have diameters on the order of 100nm and lengths of up to a few microns. https://t.co/sAM5OxPSil
There are several groups working on nanowire growth and their application in devices. I've had the pleasure of working with @i_morral group @EPFL_en, who can answer any tricky questions! But one of the main advantages of nanowires is the chance to build heterostructures https://t.co/8dSpwU6RDA
We can theoretically take any two materials (even if they are lattice mismatched) and grow an axial or radial heterostructure. Axial heterostructures can build p-n junctions for transistors and solar cells, whereas radial heterostructures are crucial for building nanowire lasers
We can effectively build this structures from the atom up! We can add dopants to build customised heterostructures for specific device applications, allowing us to design their optoelectronic properties from the start. https://t.co/s8eo4X6Xf1
But the best advantage of #nanowires, is that they have comparable optoelectronic performance to bulk materials! They maintain high electron mobilities (high device speeds) while reducing material composition. So expect to see nanowires in your devices soon!
So yesterday, we looked at the use of #nanomaterials as building blocks for nanodevices. But are there any other exciting materials that could influence society? I'm currently interested in some new exotic materials called topological insulators. #research #STEM https://t.co/FJqb7OJ9Vt
These materials are really weird! They are insulating in the bulk but highly conductive at the surface. So the middle of the material can't support any electrical currents but the surface hosts fast electrical currents (~100 times faster than silicon) - great for #electronics https://t.co/OCphBij1PT
These surface currents are spin polarised. There are two channels - one for electrons with spin up and one for electrons with spin down. This allows us to carry twice as much information - we can use both the charge of an electron and its spin to give us an on/off signal.
But the coolest thing about these materials, is that they are topologically protected! Surface electrons cannot be backscattered from defects or impurities (they just carry on through). They travel as if on a tramline or ice rink - in one direction with less heat and resistance. https://t.co/0crpOTjdY9
Topological materials are great candidates for #electronic #spintronic and #photonic devices and could provide a step change in performance and energy efficiency! Recent research has also shown that they could push devices into the #terahertz range! https://t.co/9ZchOktUMv
Good morning everyone! I hope you enjoyed seeing a small snapshot of my #research. Today is my last day of tweeting for @RealSci_Nano and I would like to share my experiences as a #deaf/hard of hearing #researcher and discuss topic close to my heart...…#accessibility in #STEM https://t.co/Y685zb3Yjy
I've been hard of hearing since birth and rely on #lipreading for everyday communication. I got #hearingaids when I was around 14 and have had a love/hate relationship with them ever since. I recently started learning #BritishSignLanguage again and am using it more and more
Lot's of people have asked what it's like being #disabled in #STEM and it is always an interesting question for me.. First, I don't feel or identify as #disabled - it is a term I use to access support and reasonable adjustments, but I am #scientist, #engineer and Jessie foremost!
My #disability is a hidden disability, so some of my colleagues out there may not even be aware that I am #deaf (surprise!). Up until studying for my PhD, I tried to hide my deafness and fit into a #hearing world. Now, I much more proud and open about it.
Looking back, I was afraid to talk about my deafness and ask for support because I didn't want to be 'different' or a 'hassle'. I felt like a problem. I didn't want to miss out on opportunities because of #unconsciousbias or the fact that I needed subtitles, microphones, etc.
The lack of these adjustments made events (such as conferences) inaccessible for me. If we everyone to participate in #STEM equally, we need to remove these barriers and make STEM #accessible. And we need to start by asking is STEM #equal #diverse and #inclusive and #accessible? https://t.co/BxQwqIwbRt
#accessibility benefits everyone not just #disabled #researchers. For example, small changes, such as using microphones at conferences, will make a huge difference to researchers who are hard of hearing, but will also make life easier for everyone!
So I would like to start a discussion around #accessibility . Please feel free to ask any questions you may have about my experience and barriers facing #disabled #researchers.
@jemimatabeart Hi Jemima. Thanks for the question! Moving to online webinars has been one of the most difficult parts of lockdown for me. I've found that a lot of conferencing tools don't have good subtitles so have had to rely on remote captioning and occasional #BSL interpretation.
@jemimatabeart Zoom is the most popular tool at work but doesn't have automatic captioning. Microsoft teams does but only if you have a subscription, so it's been a lot of extra work organising my support. However, one positive is that there is more research and push for AI for captioning
@jemimatabeart I've started using https://t.co/9hOEeS92Ru from @aimediaUK, which has been a useful backup for when there isn't subtitling or no palantypists have been available. It is free and helps, but doesn't cope well with #STEM vocab. One of the simplest things that helps is turn-taking:
@jemimatabeart @aimediaUK Keeping the pace slow in meetings, leaving your video on for #lipreading and turntaking really help with video conferencing. There are some tips in this blog I co-wrote with @BMatB @EstOdek Odek @webmz_ @jesswade : https://t.co/uPLBSaU8XX
@luke_phys Hey Luke! Hope you're doing well. Great question! For digital events, there are guidelines from @w3c to make content accessible. https://t.co/QtYbYkmx6N @DisabilitySmart have also realised an inclusive toolkit for communication and have great resources https://t.co/j7ncJ1VX2b
@luke_phys @w3c @DisabilitySmart @nadsn_uk have loads of resources on their website: https://t.co/B2DteTClPl and the FDA also have some nice guidelines https://t.co/01bejGhmXU https://t.co/DMh3yKfbhs
Want to know more about the barriers facing #disabled researchers and what can be done to address them? Check out this interview with @katesang @DisabilityIncl1 https://t.co/U9PtuVwtKG
There is also a great article from @ncjbrown on #Ableism in #academia - it presents #research in this area to 'provide food for thought, stimulate a debate and #raiseawareness'. Please check it out! https://t.co/MVV7VPrP7S
@jemimatabeart I know! I use the auto-transcription a lot for recording lectures so its heartbreaking it doesn't work live :( Fingers crossed Zoom will add this soon!
So how can you be an #ally to #disabled researchers? First, when considering #accessibility in your events and institutions, engage us! We have a whole wealth of knowledge from lived experience to contribute. Ask us what we need and how you can support. #nothingaboutuswithoutus
Put #accessibility first at the very start of any design process or discussion. This ensures #inclusivity and #accessibility is embedded at all stages (It also saves time and cost later on!) Consulting with your local #disabled staff network is a great way to do this. @nadsn_uk
There are also little changes that all of us can make. For example, why not make sure you use and ask others to use a microphone at conferences? If you are making a new lecture course, could you make sure all your resources use sans serif font with minimum font size 12?
#accessibility is about #raisingawareness and making small changes that will make a huge difference to others in #STEM, so I would like to ask all of you today to identify one small change you can make and to think about #accessibility in your #research #allypledge
@_SimonLau @jemimatabeart @aimediaUK @otter_ai Thanks Simon for the tip. I know you can manage the vocabulary if you get the premium version but don't want to pay for it out my own pocket. I was under the impression this was still limited to 200 words? The AI is still not as good as a palantypist for me yet but hopeful!
@_SimonLau @jemimatabeart @aimediaUK @otter_ai Thanks Simon that's great. It could also be my brummie accent it hates.... Will DM :D
So I am about to sign out and start my holiday in the sun! Thanks everyone for joining me this week talking about #terahertz radiation, #nanomaterials, #topological insulators and #accessibility in #STEM. I've had a lot of fun and hope you have too! Feel free to DM @drjessboland
[admin] Thank you Jessica for a wonderful week! Do give her a follow. @DrJessBoland on our podcasts - https://t.co/qFkHdl9uns https://t.co/TWbt5LcMhY
Irene Suarez-Martinez
[admin] "Family Tree of Carbon" Please welcome @IreneSuaMar on @RealSci_Nano. Listen to the #71 Under the Microscope podcast to know what is coming your way this week - https://t.co/XTnX8MWVhm
This week I (@irenesuamar) will be taking over this handle. I will tell you about myself, carbon nanoscience, crafts, work part-time ... PS. I love gifs, so embrace yourselves :) https://t.co/fyP4fTGkuw
I currently work at Curtin University in the beautiful city of Perth in Western Australia (all the way to the left from Bart's finger). I came to Perth for a two year post-doc position with a temporal visa (I am Spanish) ... that was 10.5 years ago https://t.co/IdRjxZwgxM
My research career has been dedicated pretty much to its entirety to one element and one element only! So the idea its that this week I will talk about the different #carbonmaterials, specially those in the nanorange. https://t.co/9CaRmWSWvw
disclaimer: I have also add boron, oxygen, fluorine, hydrogen and some metals in a few occasions into my affair with Carbon. I have "cheated on" Carbon with Silicon a few times.
@jesswade During my first scientific talk on graphite I continuously said 'shit' instead of 'sheet'. Now, many years after, I still cant get myself to use 'sheet' and I mostly say 'layer' (and laugh to myself everytime)
@johnazariah What do you do/know with C&F ? I worked on carbon nanotubes with F and Au. We did plasma treatment of nanotubes with CF4 and decoration with Au. We thought F may create defect sites on the tube surface, but it didnt as much as O did. And in fact, the Au "cleaned up" a lot of F!
If only we could make graphene this way... https://t.co/KYhVNYx2CT
I have worked part time the last 5 years. Today is my day home with “nano-me” and “micro-me” :). My daughters make me think on one of the highlights of the nano materials: surface area. Micro-me’s looks like a mini version of me (aka the bulk) but nano-me looks very different. https://t.co/mBYDl9YZRm
While working in France, Chris Ewels and I made a little video explaining how materials in the nanoscale have extremely large surface area.... Enjoy our video 'Nanocheese' https://t.co/xMFQuIe7IH
RT @WomenInSTEMAu: “Let’s create a #flexible skills-based economy where a person’s education continues throughout their life, enabling them…
Mark your diaries people! Online for those not in Sydney.. although I feel the time is going to be painful at least for me in Perth. Any chance it will be available on demand? https://t.co/eHQDnYeyWO
Working effectively parttime is not an easy task. For a long time, I felt I was constantly “putting fires away”...having time to just deal the tasks that would have been catastrophic if weren’t done. Seems a cliche but saying “no”, delegating and letting go of perfectionism helps
In my case, I chose to work parttime for my kids. With my oldest I worked 3day/week ... it was a car-crashed. I got nothing done, it was very stressful. But I have a partner and I was lucky he could also do parttime. With my youngest we are doing 4 days/week each. Share the load!
Are you about to start parttime in your scientific career? My recommendation is that if it is more than one day a week, you choose non-consecutive days (or you will spend your next day trying to remember what you were up to).
And another (somehow) related recommendation/reminder ... specially for us women with kids... do your pelvic exercises :)
RT @eMenkah: I'm a computational chemist #postdoc with keen interest in high performance computing #hpc and method development. I've got a…
What did I mean with "family tree of carbon"? There are plenty of materials made out (exclusively-ish) of carbon atoms. In the bulk: diamond, graphite, amorphous carbon. In the nanoscale: a plethora of them! Some "pretty famous" like graphene & nanotubes, some more obscure... https://t.co/K7LuVYP5hr
I want to talk briefly about THE fullerene, #buckminsterfullerene. Much has been written about this molecule, 60 carbon atoms arrange in a close cage. It has changed the way researchers think about carbon materials.
This is the paper in Nature for which in 1996 Kroto, Smalley and Curl won the Nobel prize of Chemistry. Experiments were performed between 1st-9th of September 1985, the paper was submitted on the 13th of September, publication on the 14th of November! Isn’t it amazing? https://t.co/yIYiwHSpm0
Just for fun a short video I made about C60 and schlegel representations (2D representation of fullerenes) – feel free to nominate me for the Oscars :) https://t.co/APVldMSp3t
Did you know that the ratio of soccer ball diameter to the Earth diameter is the same as the ratio of the diameter of C60 to the soccer ball diameter?? Jonathan Hare told me about it. If you want to know more about C60, @JonathanHareC60 is your man!
I've always enjoyed making artistic images. For a while, I submitted a suggestion for the journal cover to almost every article I published. Life got to busy and I stopped. I recently suggested one and the journal is asking for money! What is happening?! Is that "the new normal"?
So many carbon nanoforms that I even wrote an “encyclopaedia” of them 😂 - just chapter but I promise there are lots! Brownie points for whoever can match that book cover to a Taylor Swift or Beyoncé outfit 😂 https://t.co/n5qNFngDLH
@RKarsthof That must be researchers promoting that they got a cover (welldone if you have one! Go you!!) But surely now that everything is online no one has the paper issue on their coffee table at the staff room... so getting a cover is more pride that anything else, right?
@RKarsthof True... it makes up for a cool intro in a talk too. :) Congrats on yours! And I love the idea of displaying them as poster on&out your office. I’m off to the printers (for those that were accepted and those that didn’t! :))
[admin] "Family Tree of Carbon" Extended conversation with the amazing @IreneSuaMar is out now https://t.co/0vEwMT9PgL
@MinoritySTEM I wish twitter allow more than just one like because I loooooive it! What a great idea! Is that thesis writting at the end? Good luck and looking forward to see the product!
RT @CL_Bentley: First tweet! I have two fully funded PhD scholarships available in my group at @ChemistryMonash, starting November 2020 onw…
One of the things that stroke me the most when I started research into carbon nanoforms was the names... still to these date I am not sure if there are genius or the silliest idea in science... Let's go through (by no means) a comprehensive list
Let’s start easy: C60 also known as buckminsterfullerene in reference to the architect Richard Buckminster Fuller whose dome have the structure those molecules cages (with the pentagons and hexagons). “We” even added the -ene to refer to the double bonds /alkenes. Good one! https://t.co/072OBmuDO4
A single layer from the graphite structure is known as graphene. I quite like this name, with the “graph-“ from graphite and the “-ene” to refer to the aromatic double bonds /alkenes. 10/10 for the name in my opinion! https://t.co/OcWqqiDnmb
Carbon nanotubes… well, that was just lazy, wasn’t it? 😂 No wait! We can add the number of walls: single-walled carbon nanotubes, double-walled, multi-walled… ohh then it is ok. https://t.co/LKQeQNQuUP
Concentric fullerenes are known as carbon onions. “We” were getting creative and funny now 😆😉 https://t.co/k2cGWruHcZ
When a nanotube is filled with fullerenes it is known as a peapod. The fullerene-people had the best names! But do I feel a food-theme here? https://t.co/DxcwFSqQ3v
well... carbon tubular structures that look like these under the electron microscope are known as herringbones… it smells fishy here. https://t.co/az1A9LXEM5
What happens when you rolled up a graphene sheet like in a scroll…. You get a carbon nanoscroll. And that is it, you got the name: carbon nanoscrolls. https://t.co/VgzVXMQB7j
A graphene sheet in a conical shape will be a nanocone but similar structures also appear in clusters which may look like and is known as dhalia https://t.co/CqOPiEzA7i
Now this starts to get “dangerous” because if we are going to use the name of macroscopic things that resemble the nanostructure… where you see a duck, I may see a rabbit. https://t.co/gKVV5Koopb
When the “sticky” cones are pretty long and the center is full, we have multiple names depending where you are from: sea urcid, durian or chestnut. Ok, that starts to be a problem for a good nomenclature. https://t.co/czYQibqt0h
What about this? Well… the possibilities are (almost) endless. I have seen nanotorus, crop-circles, toroidal fullerenes, nanohoops, carbon-based toroids, doughnut-shaped tubes, and carbon nanotube rings. Good luck putting that for a search in a literature review. https://t.co/qvDpgNdSL2
One of the best 😂: dog-bones. When large diameter single and double-walled nanotubes collapse so the cross-section looks like a bone. Well, that is what I would call drawing a long bow 🤣😂 https://t.co/a0J6IG7jk8
@EmmRankinWilson Who doesnt!? It is such lovely molecule :)
@chabis_ch 🤣😂so true. Sprinkle some glitter on it and we have everything we need
@robynephd Actually it is way to get double walled nanotubes. If you heat them up the fullerenes fused together and form an inner tube. Also good with balsamic vinegar 😂
@chabis_ch I know... Someone was feeling creative and now it is just confusing.
One that gets on my nerves is buckypaper which is film made of an agglomeration of carbon nanotubes - with no fullerenes!! just carbon nanotubes!!! WHY THE "BUCKY"??!!!! https://t.co/5BoVDNZkHC
@OptoLia actually there is quite a lot of controversy with the torus. There have been a few experiments that claimed they have seen them but ... are they "actually" a ring or a coil?
@MySci_PK They are as cute as a nanoform can be :) Quite fun when you heat them up and they start to wiggle and the fullerenes fused. It was the topic of my first "Australian" paper with Molecular Dynamics so they are close to my heart https://t.co/zVnivsQFF4
@smileyATI What? I think carbon nanofoams are super fun! It is like “let’s chuck every nano structure and apply periodic boundary conditions” hahaha You get everything! ✅ pentagons ✅heptagons ✅dislocations ✅ curvature... Can you tell I’m a modeller?
Given my surname (Suarez-Martinez) this may take me the whole day.... https://t.co/OyKkSOmBe2
RT @tigerinstemm: Next, in the TIGER in STEMM summer webinar series in #physics, will be back-to-back talks by Dr Idris Ajia & Dr Kate Oliv…
Look! half-fullerene flying! https://t.co/9quHN6zdcs
Random piece of carbon-materials information #1: the term "turbostratic" was coined by B.E. Warren with the help of his chemist friend Nick Milas. It is used to describe the random stacking of the layers in graphite (aka. turbostratic graphite) https://t.co/jlMuTXafn8
@TsundokuPuzzle I have apostrophes on both on my surnames but I never use them in "the scientific environment" as it is too confusing. I wonder how many of us change our names to make them "more google-able"..🤔
@svenja_lohmann @realsci_DE @AcademicChatter Yes I would mention them
That has made me day! New toilets opening soon! And not any toilets! #inclusivity Ps. The physics building has currently one female toilet only 😭 https://t.co/Ey3FZyVo0y
Not only I research carbon nano science. I wear carbon nanoscience 😂 Also my memory is terrible. If you can’t remember at which point in the Brillouin zone is the zero band gap for graphene, then embroider its band structure to your skirt! https://t.co/m89I5HLY0h
My next #sciencegarment needs to be around the electronic properties of carbon nanotubes because that is also something I always forget which way around that is! PS. armchair tubes are always metallic, zigzag tubes are semiconductors unless (n-m) is a multiple of 3
@goldclusters It is mathematical trickery :) https://t.co/ctzQtzcAZ3
Or maybe I should channel Millie Dresselhaus, the Queen of Carbon, and knit a replica of her fabulous red cardigan. Do you know she often wear that same cardigan when press or some event was happening? She was so lovely, she is so missed https://t.co/0vqn5gOMwp
Mildred Dresselhaus was a power house in carbon science, not only in nano but also in bulk materials. She was funny, clever and a very talented scientist. Check out her interview: https://t.co/ZmSM4EAlKt https://t.co/ZIXywCXNzl
@Lolchu It is a skirt that I made. The pattern is the Yasmine from Maria Denmark). The band structure is my #handembroidery, I worked out I had to repeat the unit (reciprocal lattice) 15 times to go nicely all around the hem.
RT @SydneyNano: Registration for this event has now closed. You can still join the seminar Via Zoom at 9:00 am. See you there! https://t.c…
@Lolchu The bonding in nt is very similar to bonding graphene/graphite. There are three sigma covalent bonds in the layers (3 e-) and then one e- in Pi bonding. The pi electron cloud outside and inside the tube are a bit different because of the strain (specially in narrow tubes)
@Lolchu The C-C bonding during growth is modulated by a metal catalysts, so it may include radicals. I’m not on top of the details on NT growth
Never thought about this before, but yeah, I also do that. Who can get a new paper just after one was submitted with the same energy as during submission? Specially since online submission sucks your soul out... more than three authors? Book a whole day for the submission https://t.co/kIM9ZmNJ7M
@Vijay_Jayswal20 Yep, that is a problem https://t.co/AxBLtqzWvs
You are not alone... I hope reviewers, employers, ourselves, etc realise this and we are kind to each other. I hear constantly in the news how business have a lot of of trouble with this stop/start situation... well research has that problem too https://t.co/qR3AohWeTR
Random piece of information about carbon materials #2: carbon is the only element with TWO journals exclusively dedicated to it!
@Vijay_Jayswal20 Polymer scientists? Organic chemists? Anyone? Someone? https://t.co/flTg6kAxAz
Do u also get these holes on tshirts? They are caused because the weak T-shirt rubs on the jeans. I wish tshirts were made with some super strong yarn... nanotube-based yarn anyone? Im open for collaborations - you made the yarn and I will knit and model it :) https://t.co/DB98w9uelL
I will model it and I will make models of it (in and outside the computer :D) .. it wont be the first time.. not even the second time... https://t.co/xy77u5I2ZQ
Generating atomistic models of carbon nanostructures is not as easy as it looks. In the case of nanotube, you can write a code yourself. I made one a pretty rudimentary one for scrolls.
Fullerenes and capped nanotubes are quite complicate. Some are available from Yoshida's library https://t.co/meihSnxkew but my clever friend Mark Robinson wrote a nice code (NanoCap) to make any C_n fullerene and capped any chiral tube! https://t.co/D0aW4XcOI5
@SimonCvijanovic @KyleChisek @upulie and you will get graphite
@KyleChisek @upulie You can convert your ashes into diamond. I remember seen a company that did that... but takes quite a lot of energy.. not very environmentally friendly.
@SimonCvijanovic @KyleChisek @upulie I have few more years to wait for the result :D ... but the most stable form of carbon is not diamond but graphite, so thermodynamics tell us
@SimonCvijanovic @KyleChisek @upulie I dont think those frequencies will do much to diamond. With enough heat you can certainly carbonised your sugar in the absence of O2 but if oxygen is present you will just make CO2 and CO from both the diamond and the sugar
Diamonds are graphite in disguise 🤣🥸🥸😂 https://t.co/zDmrAYONaE
@zubairchandio1 @XianjueC https://t.co/iUkB1tBR59
@SimonCvijanovic @KyleChisek @upulie The universe, the sex of the angels, what to have for dinner? Everything and anything is worth thinking about it if it interests you!
@SimonCvijanovic @KyleChisek @upulie Diamonds are also grown using CVD, chemical vapor deposition. I don’t know the pressures used there... maybe that would inspire you on your “sugar experiments” :)
@XianjueC Isn’t the current “holy grail” in 2D materials to be able to sandwich them? Maybe I’m 50 years we can sandwich them and eat them 😀
RT @cshperspectives: Journal Impact Factors are useful measures of article quality
RT @Volcanologist: On maternity leave, maternity cover and the generation of short-term posts in academia...
Materials that prevent pollution of the environment ? 🤨🤔🤔 although I’m worry we need that sooner than in 50 years. https://t.co/dyFLXnTlx5
@astrophysikerin Not sure anyone has actually tested them 😀 but I think carbon nanotubes are stronger than cats claws. And now I wonder... what is the tensile strength of cat claws? 🤔 and the Young’s modulus? 🤔
It is Friday afternoon here in Perth.. I think we need some fun educational videos .. so check this animated red lipstick nanotube reporter who will tell you everything you need to know about carbon nanotubes https://t.co/gPt637DAyZ
When I was in France, I got some funds though WomenInNano. The red lipstick nanotube reporter and I visited @OxfordMaterials and made more more videos about the synthesis of carbon nanotubes https://t.co/cztjVgaau7
My favourite video from the "nanoseries" is this one. Get a nanotube samples and let's zoom in! https://t.co/yjl6bFzxp8
The playlist is also available in Spanish (narrated by yours truly) https://t.co/gl2R5v8jus and French (narrated by the lovely Isabelle Riou) https://t.co/eROhtB0e9b
I remember when I first got invite. As I was trying to “sell this opportunity” to my supervisor of the time, he just said “I can’t teach you that lesson, you need to live through it and learnt it yourself.... sure go for it”. Wise advice ... yep, I did learn the lesson https://t.co/KDzW9JQ9dZ
Perception and stereotypes: Stop asking "who is your supervisor?" maybe just ask "what do you at University of blabla?" and let people tell you. I'm short and I look young. If I had a penny for everytime people assume I'm a PhD/postdoc, I could fund quite a few science projects
Once I gave a talk that I titled: "a jungle of carbon nanoforms: is the nanotube the king?". After my talk, someone said to me they were surprised when I stood up to present, they expected an old prof. Those words have been hunting me for years, mixture of proud but also sadness
In case you wonder, "in the jungle of carbon nanoforms" the nanotube is not the king for me. The nanocone is King! because they combined all the interesting things in carbon chemistry :) https://t.co/eSYlF9KSP2
@lisaharveysmith just wondering now ... how did you think it was spelt? It is pretty easy word for a spanish speaker. The one that always gets me is “Angstroms” (I actually had to google it to put it here!)
@lisaharveysmith Sooo close https://t.co/3teUvA6kDu
RT @trevin: This is so perfect. https://t.co/Qc8qy3wmPV
RT @druselabs1: Iron sulfide aka fool's gold Pyrite #crystal https://t.co/eytAMDt25U
This week I have told you about some of the many forms of carbon. The family is big and diverse! https://t.co/K7LuVYP5hr
Many forms can be "obtained" from a single graphene sheet. Most of these modification cant be done for real, they are just "thought experiments" but it groups forms in smaller sub-families with Graphene as the "ultimate ancestor". https://t.co/9Y7iWH4b4E
I see that family tree a bit like a periodic table of carbon nanoforms. If you want to know more, I wrote an invited editorial with Chris Ewels and Nicole Grobert in the journal Carbon (and I also made the cover :) ) https://t.co/okbvKZ1Ai6
Time has come to say goodbye my friends. I hope you had as much fun as I had. If you have questions, want to send me any silly nano names (that is always fun!), or follow my progress on sewing science garments, you can find me @IreneSuaMar
I leave you with my current knitting WIP, the graphene sweater. (Pattern from @dreareneeknits who was thinking of bees... but I think we can all agree here that it is GRAPHENE! :) right?) https://t.co/v0Oti7burd
[admin] Thank you @IreneSuaMar for a wonderful week of carbon science! Do give her a follow and listen to her podcasts - https://t.co/0vEwMT9PgL https://t.co/CPR4ZqiznQ
Eleonora D'Elia
[admin] "The Brilliance of Smart Materials" Please welcome @DrEleonoraDElia for a week of amazing science! Listen to the podcast to know what is coming your way - https://t.co/dDoQS7ZYlp
Goodmorning everyone!!! Wow, what a week to be taking over. Let's hope 2020 is kind to us this week. I don't use twitter much, so be nice to me, it took me about 5 minutes before I figured out how to take over this account 😅 I'll be slow, but it'll be worth it, I promise!
So, to start off, a bit about me: I'm from Italy, the land of food, sun, and Pizza/Pasta/ and.. NO, Garlic bread is not a thing in Italy!!! So, how did I start science? Pretty much just by mixing everything I found in the house when I was about 5. Mum loved me (not). Much fun! https://t.co/7KcI2GqLwo
Then choosing between: art, architecture, electronics, science or a career in singing, I decided that materials science was a good compromise. Makes sense, right? I love colours and magic, and pretty much materials science can do all of this for you. Look at this pretty rock!😍 https://t.co/fbef41elXj
Went to @imperialcollege for an MSc in biomaterials as I 💙Bioglass, an incredible material created by Prof L.Hench in the 1960s. If in contact with bone, Bioglass stimulates its regeneration and biodegrades during the process. @julianrjones is now at the forefront of this field.
I then got offered a PhD in Smart Materials @ImpMaterials with Prof Eduardo Saiz and Dr Jon Weaver and being paid for studying sounded like a great idea... until it came the time to start writing my thesis. Terrible terrible idea then. https://t.co/OGlWc5lUmW
After 2 years of post doc on Smart Materials where I was working on this super cool material that could do everything even prepare coffee in the morning (or not), I became a Teaching Fellow in the Dept of Materials at Imperial College, I teach UG Students and do lots of Outreach!
And there you have it, a short intro to my life. Phew, that was hard! Oh, I am also a mum, friendly advice, don't ever have kids if you want to sleep ever again. https://t.co/TuxPOphOrS
Starting off with colours and magic: Did you know most blue colours you see in nature are not due to a pigment but to structural colours? This means the colour in 🦋 is due to light interacting with very small features on the wings which are about the wavelength of light. https://t.co/cgcALBojnZ
The same happens in sea shells for example. The awesome iridescence you see on them is due to the very small hexagonal platelets of Calcium Carbonate which are in the range of 400-600nm thick, again, the wavelength of light! On Nature, you awesome thing! https://t.co/YTWm2H1hcz
Can us scientists make this happen in the lab? Yes, if we use a technique called "micropatterning", where essentially we can take a surface and transform it to create small features that would reflect light like a prism does. we do this for example in Diffraction Grating Film.👇 https://t.co/VTYuyXBMaj
@nadiahhusseini ask away questions on my profile or on my tweet if you want. I'd be happy to explain in more detail :)
@nadiahhusseini Great question! There are many different techniques and they mostly depend on the type of material you are working on. Diffraction films are often obtained by photolitography, which works by exposing a substrate to light through a "mask" that determines the pattern on the surface
@nadiahhusseini Then once this "mask" has been imprinted on the surface, you have chemical treatments that allow the erosion of only those selected areas on the film. You can also use photosensitive gels (but they don't create micropatterns,they use the change in refractive index within the gel)
@nadiahhusseini Together with those techniques, you can create synthetic opals for example by depositing microsphere of polystyrene on a substrate. this has the same effect. Look at this video for example. The results are incredible (second link). https://t.co/pgR5zZhuE5 https://t.co/MwWWFpUuek
For tonight I'll leave you with an exp to demonstrate the difference between pigment and structural colour on🦋. Using a drop of alcohol on both, the colour temporarily disappears from the blue🦋due to the small channels being filled. No change is seen on the pigmented butterfly. https://t.co/Vw4BdBQYbC
When the alcohol evaporates, the colour on the blue butterfly comes back, as the channels are now free and light can interact with them again. Look at me, I've even made my first GIF, so proud! @ahugumrah taught me this experiment and she is the BOSS in this field!
Hope you all have colourful dreams tonight! 🌈 Early night for me as 2yo could wake up at any moment 😱 Disclaimer: No butterflies were harmed in the process.
@MinoritySTEM @NatalieGCheung Relatability - talk about subjects students have some knowledge of (e.g. smartphones, who doesn't have one?) Language - Keep the jargon to a minimum and explain everything you say. Context - Provide a story/background, something to keep them wanting to know "how it ends" ...1/2
@MinoritySTEM @NatalieGCheung Excitement - Show enthusiasm for the subject, whatever it is! Discovery - Now introduce new ideas they might not have heard of, but in a fascinating new light! Future - Provide context for what could be done next/where this discovery could lead to.
@MinoritySTEM @NatalieGCheung There is also the issue of age, different audiences will need different methods of communication. 14-18 YO respond better to challenges 9-14 to group work and exploring things in detail 4-9 to "amazing" fun new subjects!
Good Morning y'all! Today we'll have a chat about... drumroll... Liquid Crystals!!! Starting off with a short video about Thermochromic Liquid Crystals, I'm hoping you'll come out of if knowing some more about these fascinating smart materials. https://t.co/lKuUpCjRPg
RT @MinoritySTEM: Great tips from @DrEleonoraDElia who is on the @RealSci_Nano account this week for ENGAGING YOUNG PEOPLE WITH STEM What…
This beautiful piece deserves everyone's attention. I want one! Unsure as to how this wonder works? watch the video I posted earlier today :) https://t.co/4OthwiwoeQ
So, we know now how liquid crystals work, what happens in LCD Displays? White light passes through a polariser, gets "twisted" by a layer of liquid crystals and is then filtered through a second polariser. If we apply a voltage to the LC, there is no twisting, so we see black. https://t.co/8yVxUK6Juh
This happens because the voltage "breaks" the order of the molecules in LCs. What is a polariser? A thin patterned film that functions as a light filter. Only light with a particular "direction" (ie polarisation) will pass. So, 2 ⊥ polarisers will not let any light through.👇GIF https://t.co/g40wlS3Z9x
And the coolest thing happened today as I was trying to make GIFs for you on linear polarisers, look what happens if I place a linear polarising filter in front of a Thermochromic Liquid Crystal sheet 😍🌈 https://t.co/jZINlDzbCq
[admin] "The Brilliance of Smart Materials" @DrEleonoraDElia gets candid on #74 Under the Microscope This podcast is a deeper dive into the world of smart materials. https://t.co/R062qPcHzS
Today is my 2yo Toddler day, so tweeting or having coherent thoughts is nearly impossible. Too stressful. Normal services will resume tomorrow. Meanwhile, did you know that materials can get stressed too sometimes? Here you have Birefringence, stresses shown through polarisers. https://t.co/2PvHUqo3pO
Plastics that have been moulded often show accumulation of stresses in particular areas of a sample. Studying stress concentration is very useful in materials science to understand possible mechanisms of failure and crack propagation.
Today is World Self-Healing Day. Joking, just made it up, but we are talking about self-healing materials today. So here is me 10 years ago, synthesising my first self-healing polymer: Silly Putty! (I know, I made a portrait video, I'm sorry 🥺) I was so proud of myself! https://t.co/FZAvguVtZ0
Silly putty is probably one of the first examples of man-made self-healing materials. As usual, Nature does it first, take skin, bones🦴...But did you know also inanimate objects could repair on their own? It's only a handful of them tbf, and it is due to their chemical structure https://t.co/47uo9QHqnm
The Self-Healing skills of this material are due to Dynamic or reversible bonds. In the case of Silly putty there are hydrogen bonds (same ones you have in water, quite weak) and some Si–O : B bonds. These links can be broken fairly easily however they also reform very easily!
Now you might think: well, silly putty is quite weak though, how can you possibly use it in anything? Here is were composites open up an incredible world of possibilities! You could have a self-healing mortar within a brick structure: once the crack closes, the material heals. https://t.co/GRUmOHNj7v
For anyone with #impostersyndrome today. I think I just melted. https://t.co/shmYxr6iAW
RT @tigerinstemm: Today!! Don't miss the latest in our Summer Webinar Series in Physics! You can register here: https://t.co/EBLRLaowls or…
Imagine having a super light conductive graphene foam and infiltrating it with a self-healing polymer. Now you have a conductive AND self-healing material. This means that you can pass a current through it and speed up the healing. What took hrs to achieve now is done in minutes. https://t.co/yy7O7zfcsX
Again with the vertical videos, I know... I was young and naive. However this shows you the power of using composites! And what else could this little guy do now? (next tweet in the thread...) https://t.co/SbmxxFf0cO
It can also FEEL when it's being damaged! If a crack propagates through the material, the graphene network will break, reducing therefore its conductivity! Once placed back together, it will however fully heal and go back to its original conductivity. Oh I 💙Smart Materials. https://t.co/bH7g519V3J
The amazing world of Shape Memory doesn't end at Nickel Titanium Alloys "remembering" their original shape when heated up in hot water. Some Brass Alloys have a 2-way memory! Remembering a high🔥temperature shape and a low❄️temperature one, and can cycle between the 2 infinitely https://t.co/r9RQOLAXgU
Now things get interesting: If we combine a shape-memory polymer with a superlight 🪶 graphene foam, what we get is an amazing composite that can change shape just having a small voltage applied to it, and still be strong enough to lift a load 100X its own weight!💪 https://t.co/QmKZBiICAE
The thermal image shows that the current applied to the composites heats it up to about 50C, enough to activate its shape memory function and have it grab an object! This was part of my post-doc work a few years ago. Tell me that you don't want to study Materials Science now!
@HelmanDaniel Good Q! To activate the flow you would probably have to use more energy than the electricity you would be able to collect. Also, not sure how easily the surface transfer would be between the ions in the fluid and the graphene. Mhh, want me to send you a GFfoam so you can try? 😃
RT @JoYurcaba: yeah sex is cool but have you ever had an editor say "This looks great! I don't really have any edits"
As a slight deviation from science, I love painting and I find it really helps with anxiety. Mental health issues are not properly acknowledged in science and academia and often it all gets a bit too much. Here's one of my de-stress evening digital paintings. @DrEleonoraDElia https://t.co/T1jBdgAmdp
RT @Ri_Science: DRUMROLL PLEASE Our 2020 Christmas Lecturers are Chris Jackson, Helen Czerski & Tara Shine! In 'Planet Earth: A user's gu…
So, That's all Folks! Thank you for following my ramblings about smart materials this week, it has been a pleasure to create content for this awesome account. Hope you had fun :) Enjoy next week's amazing scientist! See You Soon! 💙
[admin] Thank you Eleonora for a wonderful week of science, especially the videos 🙂 Do give @DrEleonoraDElia a follow and listen to the podcat to know about her work https://t.co/R062qPcHzS https://t.co/QeOv71dGxj
Georgina Zimbitas
[admin] "Nanobits in Water" Please welcome @zimbitas and listen to the podcast to know what is coming your way this week https://t.co/LtqpoQFRyt
Hello everybody! This week I will be taking over @RealSci_Nano! I will be talking about small molecules and how they are seen to form nanoclusters in water! Today, though, I will be introducing myself.
@MySci_PK Thank you Pranoti for reminding me to inform people that I am, indeed, also known as Brian! 😄😎
I started off my research path in my home country of Australia. I miss Australia. My undergraduate at RMIT was in Applied Science (Chemistry). I soon realised I loved Physical Chemistry - it just made sense. https://t.co/gFkZBdznsO
I then went to Greece. I worked there for a while, but I knew my heart was in exploring, discovery and manufacturing via science. I went back to uni part-time and did my 4th year degree in Chemistry at the University of Athens.
After that it was the Surface Science Research Centre, Uni of Liverpool, UK. I studied epitaxial water/ice growth on periodic metal surfaces. I love surface science! Crystallisation &/or interfaces have since been major parts of my research. #crystallisation #ice #surfacescience https://t.co/2jAodNDu1A
That was the last time I was in a Science Department. From there on I ended up in Engineering, mainly Materials. Next stop, TU Delft, the Netherlands. Modelling and experimental research of internal precipitation in metal alloys. Look at the nanoscaled oxides! https://t.co/lPkPCdLiT8
Back to the UK! England first, Uni of Birmingham. I was involved in a few projects here but my main one was with properties of water-based surfactant-polymer thin films. I love films! Here's a video of 1 my experiments to test material properties of my film #films #surfactants https://t.co/BuAmfkxGbH
Scotland next! Glasgow doesn't have the best weather but it is, by far, my favourite city in the UK! At the Uni of Strathclyde I am, again, involved in various projects. My main one, though, has to do with nanoclusters! Stay tuned for more on that this week! Intro over & out! https://t.co/8CI3fJnjsZ
Today I will talk a bit about Brownian Motion (BM), as it is key to understanding how my nanoclusters are observed. BM is the random movement of particles in a fluid (liquid or gas) medium. #brownianmotion
The fluid medium is made of many small molecules that collide with particles being observed. Collisions cause the particle to move in various directions, hence the randomness in the particles’ movements.
Think of it this way: notice how dust particles move in a ray of light. They are all over the place! They are moving within a fluid medium (air). The dust particles (bigger, observable) collide with the molecules of the air (smaller, undetected) & as such appear to move randomly. https://t.co/BBbAqWZV0N
It was named after Scottish Botanist Robert Brown, who first studied such fluctuations (1827). He observed, under a microscope, that parts of pollen were jittering on the surface of water. At first he thought it meant the pollen was alive. https://t.co/u5gZo1CtkG
But that was not the case. Brown, like the proper scientist he was, decided to test his hypothesis. He tried the same thing with sand, which is obviously not alive. The sand produced the same movement! What was going on? His work was forgotten for a while... https://t.co/HxY3p4jADF
In 1905 some young lad was doing his PhD in diffusion of colloidal suspensions in liquids. He combining Newtonian mechanics to thermodynamics. He observed random forces and speculated they might be Brownian Motion, which was later proved to be correct. He was Albert Einstein. https://t.co/H1sjd83jIa
So why all this talk about BM and Diffusion? Because of their size, my nano bits and pieces cannot be observed using optical microscopes. Lasers are used, but not to observe the nanoclusters directly. They are used to detect the Brownian Motion of the clusters! #lasers, #nano https://t.co/BEFaGBnH6F
Of course, there are other methods to "see" nano-sized objects, and I will refer to some throughout the week. Tomorrow, though, I will talk a bit about my current main project, my uncanny nanoclusters! See you then! https://t.co/YJhBP95kx4
[admin] "Nanobits in Water" Extended conversation with the amazing @zimbitas on #76 Under the Microscope podcast is here https://t.co/kaFW8VDdAz
So for today, a bit about the research. Recent studies have seen small molecules associate to form sub-micron clusters in some solutions. They often occur in solutions of highly soluble small molecules, e.g. concentrated protein solutions and aqueous glycine solutions. https://t.co/thW8fzCbB5
These clusters are not your ordinary clusters; they present liquid-like properties and can be fairly “large”. They are unusual, as they appear as discrete domains in the solution that contain higher solute density than the rest of the solution....
Here is the interesting bit: these domains are dispersed throughout the bulk of the solution, but are not considered a separate phase! #nano #clusters #assembly #homogeneous https://t.co/c6JcJYDW0O
So my nanoclusters are there, but the solution is homogeneous! I mentioned before that crystallisation has featured heavily throughout my research. The crystallisation process is extremely important to understand, as it is widely used in many industries...
When phase separating a solute from a supersaturated solution to form a crystalline phase, 2 main steps are involved: 1) nucleation (formation of a stable crystal nucleus), & 2) crystal growth (material added to existing crystal lattice). https://t.co/VqNOeD2Oqr
Many significant efforts have been made in the last 30 years to better understand the process. So why are these nanoclusters important? Their existence has rendered interest due their possibility of being metastable intermediates for crystallisation! https://t.co/puCjZstyRD
Experimental and theoretical computational results have led to alternate two-step processes of crystallization being proposed. One proposal suggests disordered metastable molecular assemblies are produced before nucleation of more ordered nascent crystals. https://t.co/qBARB5v0h7
Another alternative proposal sees nanoparticles form a crystal-like lattice that ultimately transforms into a molecular crystal. Recent studies focus on identifying if there is indeed a direct link between the presence of the solute molecular clusters and a crystal formation. https://t.co/mTbgfZRv4b
Whatever the case, the presence of these nanoclusters needs investigation!!! For example, the kinetics and thermodynamics of the formation of these liquid-like species is yet to be understood. #crystallisation #molecular #nano #kinetics #thermodynamics https://t.co/INIl9wQ8ik
My work involves looking at various aspects of such liquid-like clusters for nanoparticle production. Collaboration with the Uni of Edinburgh (Dr. M Sweatman, Dr. C.A. Ferreiro-Rangel) using experimental and computational data aims to answer questions regarding their stability.
Collaboration with the Uni of Sheffield sees us investigating how the presence of these clusters can influence nanoparticle formation, mainly silica (with Prof. S. Patwardhan @GreenNanoRes, and @amber_keegan) and magnetite (with Dr S. Staniland & L. Norflok).
All of this is part of the @SynBIM project which works on creating transformative knowledge and toolsets for larger-scale "green" manufacture of tunable and sustainable, synbio nanomaterials. Check it out! https://t.co/pRN20TErkb #sustainability #nanomaterials https://t.co/4QTNCOwaTA
Today I will talk about one of the main techniques I use to detect the presence of my nanoclusters: Dynamic Light Scattering (DLS).
A laser light hits the sample, whereby the light is scattered by my liquid-like clusters. A detector placed at a known angle to the incident beam picks up part of the scattered light. #laserscatter #nano https://t.co/Plt1HbZRpl
What the detector is picking up is referred to as the “speckle pattern”. This pattern fluctuates with time due to the Brownian Motion of the particles in the solution. This fluctuation is recorded by the detector, ultimately giving us the intensity (count rate) plot. https://t.co/88MSOQz3yF
@RoyDhimanSci Hello Dhiman, regarding the shape, an upcoming tweet will respond to that (short answer, it doesn't tell us much about shape!).
@RoyDhimanSci As for dimension, I will not go in depth in the tweets but yes, a lot can be determined by measuring the nanoparticles at different scatter angles (changing the detector angle). The particles' dimensions are proportionate to how quickly they diffuse (move in the sample).
@RoyDhimanSci Finally, there is no excitation wavelength measured; only the scattered laser light is detected! In fact, any excitation wavelength detected near the DLS can actually interfere with the results! Thank you for your questions Dhiman!
The time-dependent part of the speckle pattern fluctuation (intensity decaying over time) gives us the autocorrelation function. The intensity decay correlates to how fast the nanocluster is moving, i.e. diffusing in the solution. #diffusion #lightscatter https://t.co/flsOUEvKqe
Using this Stokes-Einstein equation for diffusion, and having some known parameters, the hydrodynamic radius of the detected species can be determined. https://t.co/2pbL3LHVer
But what happens if there are more than one scattering species with different sizes present in the solution? Well, things get a bit more complicated. For example, when 2 species of very different sizes are present, the autocorrelation function has two distinct decays. https://t.co/2UXiouLhw7
Generally, the DLS comes with special software that can give the user lots of info regarding the hydrodynamic radii of the species detected, as well as an indication of the degree of polydispersity of sizes scattering the light.
My systems are simple and as such I was able to write my own little Matlab script used to analyse the raw data away from the DLS computer. In light of the last few month, that script came in very handy! https://t.co/HLR7GF1eCw
I mentioned before that the DLS measures hydrodynamic radius. The hydrodynamic size (radius or diameter) is that of an equivalent hard sphere diffusing at the same rate as the species under observation. It does not tell us a lot about the shape, because it assumes it is spherical https://t.co/GYtiHDA5aM
@EmmRankinWilson Trade secrets - they don't want us to know! 😅
DLS is quick – a scan can be done anywhere between 5s up to a few minutes! Multiple scans are necessary for accuracy. Most often, it’s also non-intrusive. You can measure the same sample again on a later date, or you can measure it to check for changes occurring over time.
I use my 2 trusty DLS machines for more than detecting my snazzy nanoclusters.
For example, I recently used DLS to verify the presence of nanoassemblies of peptoids, which was part of the brilliant work in mediating activity and nano-assembly of antimicrobial peptoids led by Dr H.K. Aaron Lau (@LauResearch) here at Strathclyde. https://t.co/9ST2AnAIFc
Dr @ManlioTassieri of the Uni of Glasgow first combined novel theoretical models & DLS to determine the persistence length (Lp) of semiflexible polymers within solutions. We recently teamed up to get even more data for a more detailed model.
I even created a user-friendly Matlab script (based on his Labview script) that uses DLS data to give various properties of the polymers, including Lp. Hopefully this publication will also be out in 2020! https://t.co/OTks23Q1Xw
Tomorrow I will be back to talk about another laser scattering technique I have used, Brownian Microscopy. See you then!
Today I am going to talk a bit about Brownian Microscopy. It shares many similarities with the DLS technique such as the fact that it too uses laser light to detect entities in the nanoscale. The sample here is placed in the sample holder, and the laser light passes through it. https://t.co/CCDkWp7kyk
The light that is scattered from the nanoentities present in the sample can actually be visualised by a 20x magnification microscope that is mounted onto a camera, an example of which is seen below #nano #microscopy https://t.co/x1HlX9Vrky
The above shows a sample of Ludox in water. Each of the light points seen are due to a Ludox particle present in the water medium. Powerful software is used to track the movement of each light point. I am using NTA (nanoparticle tracking analysis) software. https://t.co/9X2m26XQfu
The NTA software follows the centre of the light point and determines the mean-square displacement, in the x and y axis, as a function of time. From there, it estimates the diffusion coefficient and, as we saw before with the DLS, the hydrodynamic size of the particles is found. https://t.co/N2om21uQud
Using NTA software allows for the determination of a size distribution profile of small particles. NTA is used for particles with a diameter of app. 10-1000 nm, whereas DLS can be used for particles as small as 1nm diameter up to even larger than a micron (in some cases). https://t.co/LF01w2kPfB
So both DLS and Brownian Microscopy rely on scattered light & Brownian Motion, but there are also differences between the two techniques.... https://t.co/6IJ2Am0gsH
A major difference is that DLS does not visualise each particle separately, but rather relies on a digital correlator to analyse the time dependent scattering intensity fluctuations. This difference is important when determining the size. #nano #nanotechnology https://t.co/YeDVAu1vhF
DLS: size is based on the intensity of fluctuations of the scattered light. NTA: size is dependent on the number of scattered light points. Both give hydrodynamic sizes, but one is intensity weighted and the other number weighted!
That is why the same sample measured with the two techniques can give similar trends, but different size results! https://t.co/F3llvwRIS5
In general, using NTA software is preferred when you are interested in determining the concentration of nanoparticles in the sample, when you have polydisperse samples and you want better resolution of size peaks, or when you have extremely dilute solutions.
That’s it for today! Join me tomorrow when I talk about other techniques used to help with detection of my nanoclusters, such as SAXS and NMR. See you then!
There are many more techniques for measuring nano-sized bits and pieces. Today I’ll be mentioning two of them, without going into too much detail - they were used as additional techniques in my research regarding my lovely nanoclusters!
First up, NMR (nuclear magnetic resonance) It is another spectroscopic technique that can be utilised to help get data on nano-sized entities, mainly of organic molecules. It is often used in advanced medical imaging techniques, such as in MRI (magnetic resonance imaging). https://t.co/08AbJahGgG
(Very!) simply put, NMR utilises a magnetic field to see at what energy ranges (in radio waves) specific nuclei of interest (e.g. protons, 1H) flip from being aligned to the field (low energy) from no longer being aligned (high energy), giving us info on the species examined. https://t.co/vAOPDJaVY8
For my nanoclusters, NMR whiz Dr John Parkinson (Strathclyde) used what is known as proton NMR Diffusion-ordered spectroscopy (1H-NMR DOSY). This type of NMR is used to obtain diffusion coefficient values. And what happens once we have the diffusion coefficient?
Yep, you guessed it – we can use the Stokes-Einstein equation to determine the hydrodynamic radius! #NMR #Diffusion https://t.co/ch1u7VwFwV
Small angle X-ray Scattering (SAXS) uses a monochromatic X-ray beam in a somewhat similar manner as DLS uses a laser....
The X-ray beam hits the sample whereby some of the X-rays are scattered by the species present in the sample. The scattered X-rays are picked up by a detector, with the scattering pattern providing info on said species. #SAXS #nano https://t.co/UA1DJErVAp
The measurements provide us with angle dependent scattered intensities I(Q), with the angular dependence being presented in terms of the scattering vector Q, as seen in the previous plots.
By recording the scattering of X-rays at various angles, SAXS allows for the acquisition of information about the size of species within a sample. From the slope of what is known as a Guinier fit (log[I(Q)] vs Q) we can obtain the radius of gyration (Rg) of the species present. https://t.co/c1BiWpnJv3
An (over)simplified definition for Rg is that it is the mass weighted average distance from the core of the species examined to each mass element in that species - it's not the same as the hydrodynamic radius (Rh)! Rg and Rh often have different values! https://t.co/UPM3EgmxeV
SAXS gives info not only about size, but also about the structure of species! The Form Factor (FF) of the sample is the scattering that occurs due to the shape of species present. By fitting the data with appropriate theoretical FF we can get an estimate of the shape! https://t.co/344X8d9mYN
That’s it for today! Tomorrow will be a small recap of the week – see you then!
So here it is, the recap of the week. It will be brief, as I live in Glasgow and I want to go out for my jog before the rain begins.... https://t.co/1gmPXMfDsr
My main current project involves research into nanoentities formed by organic, small molecules within an aqueous medium. My nanoclusters are a bit weird. https://t.co/wvTiysTrxV
They present liquid-like properties, and can sometimes be fairly “large”, as in much larger than the molecules present in the sample. They appear as discrete domains dispersed throughout the solution. https://t.co/qAOLD7xtlj
These domains contain higher solute density than the rest of the solution, and yet are not considered a separate phase! Can they, perhaps, be playing a vital role regarding pathways to crystallisation?! https://t.co/Q0XaL0FF9R
I use different spectroscopic / light scattering techniques to determine the presence, size, and sometimes the shape of my nanoclusters. I also examine them for stability under varying conditions. https://t.co/Vw3zYC1Ezd
Techniques include DLS, NTA Brownian Microscopy, SAXS and NMR. I also examine my nanoclusters’ role in the formation of other nanomaterials, such as Silica and Magnetite. https://t.co/8gGdTHcRDC
I am part of many other projects that utilise the aforementioned techniques. I like collaborations and expanding my knowledge! https://t.co/ySiukv44SX
So that’s it from me. I hope you enjoyed checking out my research this week. I had a great time disseminating it! You can find me @zimbitas for questions/queries! Brian here, over and out! https://t.co/ldTzQullBZ
@RoyDhimanSci I'm really glad you enjoyed it Dhiman, and thank you for participating with your likes and queries!
[admin] Thank you @zimbitas for an amazing week of science! Do giver her a follow! Podcasts where Georgina talks about her science are here - https://t.co/kaFW8VDdAz https://t.co/TUdNGoUXns
Olivia Geneus
[admin] "Uber at Nanoscale to Treat Cancer" Please welcome this week's @RealSci_Nano curator - @O_Ganics Listen to the podcast to know what is coming your way 👇 https://t.co/t18Lmb1kbi
RT @RealSci_Nano: [admin] Are you a materials and/or nano scientist? Do you like to talk about your research? Do you want to feature on…
Making my way to real scientists nano 😄👋🏾 Olivia (@O_Ganics) here! 4th yr. PhD Candidate in Physical Chemistry in the field of Nanotechnology/Nanomedicine. I am BEYOND excited to take over for the week 🙌🏾 https://t.co/O3Zb7XFzVO
Here’s what we have for the week: Today, I will discuss my academic journey (it’s a weird one 😅🤫) Tomorrow and Wednesday we will focus on nanotechnology and its multifaceted applications. I will also briefly discuss one of my current project 😃🙌🏾
Thursday will focus on academic resources for our undergraduate and graduate followers. & Friday will focus on discussing upcoming virtual conferences and other scientific related events
Finally, Saturday will focus on the importance of health/wellness! Because as scientists (and human beings), we tend to work non-stop. Let’s talk SELF CARE 🗣💆🏾♀️💅🏾
Let’s take a moment to digest this “itinerary” before I officially get started 🧘🏾 https://t.co/HZulF8mSiu
Let’s get started 🤗 I hold a B.S in Physics, and in Public Health. My junior yr, I took orgo 1 & 2 AND I LOVED IT🤫🙈 (yes, I know). At that moment, I wanted to explore the field of chemistry. I was intrigued. But I was already towards the end of my undergrad, I was too late.. https://t.co/qOdolabwOx
Many of you may ask “Physics & Public Health? What’s the correlation”?
Well, I knew early on that I wanted a career in a field that combined science and health (but not a medical doctor). So physics and public health made sense as a dual major....in my 17 year old college freshman head 🤷🏾♀️😅
I have no regrets in picking my majors 🤗 https://t.co/QMLMQ6lgvS
While applying to Master’s and PhD programs, I decided to also apply to chemistry programs. I told myself, if I got accepted to JUST ONE chemistry program, I would “blindly” pursue it 🙈🤷🏾♀️ https://t.co/whYb9OU53E
Luckily, I got accepted to a few chemistry programs so I had more of an option of where I wanted to go. I decided to head to SUNY at Buffalo (@UBuffalo)
Fast forward to now, I am part of a physical chemistry lab where my research incorporates various interdisciplinary chemistry topics overlapping with medicine. I develop multi-modal theranostic nanoparticles for biological applications (specifically, cancer treatment). https://t.co/bWEAW35uD7
I am also extremely passionate in helping high school and undergraduate students, especially underrepresented, transition to their undergraduate & graduate academic careers. Community development, mentoring, and representation are important to me!
Lastly, I am also a fitness trainer. Having a well balanced lifestyle is essential in order to be physically, mentally, and emotionally healthy.
It was a pleasure introducing myself and sharing my journey! Tomorrow we will start discussing the Nano field as well as my research. Stay tuned 🤗
Nanotechnology is helping to considerably improve, even revolutionize, many technology and industry sectors: information technology, homeland security, medicine, transportation, energy, food safety, and environmental science, among many others. https://t.co/37fyAr0zHP
Let’s go over a few examples and applications.
Environment 🌍 Air purification with ions, wastewater purification with nanobubbles or nanofiltration systems for heavy metals are some of its environmentally-friendly applications. Nanocatalysts are also available to make chemical reactions more efficient and less polluting.
Food 🍎🌽 Nanobiosensors can be used to detect the presence of pathogens in food or nanocomposites to improve food production.
Electronics 💻📱 Carbon nanotubes are great materials for making smaller, faster and more efficient microchips and devices, as well as lighter, more conductive and stronger quantum nanowires.
Energy Manufacturing solar panels that double the amount of sunlight converted into electricity. Nanotechnology lowers costs, produces stronger and lighter wind turbines, improves fuel efficiency and, thanks to the thermal insulation of some nanocomponents, can save energy.
Medicine 💊 1. Used to improve early diagnosis & treatment (ex. cancer). Some nanomaterials are able to attack cancer cells selectively without harming other healthy cells. 2. Used to enhance pharmaceutical products. 3. Oh and also used for vaccines 💉 🙌🏾
[admin] Full podcast is here - "Uber at Nanoscale to Treat Cancer" ft. @O_Ganics on #80 Under the Microscope https://t.co/7KkTj2lhDb
Let’s talk nanotechnology for biological applications Specifically, cancer treatment (my research)
I am developing a multi-modal nanostructure that targets and provides MR imaging of glioblastoma hypoxic tumors.
The cool thing about my particle is that it has the potential to work for ANY tumors that are resistant to therapy due to hypoxia (low oxygen and pH levels). Choosing GBM let’s me explore how well my nanoparticles cross the blood-brain-barrier
@DishPodcast Gadolinium and Manganese 😏
@DishPodcast No chelating. The Gadolinium is embedded in a fluoride lattice and coated in a Manganese shell. So we have both strong/high T1 and T2 effect
@DishPodcast My nanoparticles also has optical imaging capability
In addition to MRI, my nanoparticles also has optical imaging capabilities
@DishPodcast The entire particle itself after formulation is less than 200 nm because we want high percent transmigration (blood-brain barrier)
Having both optical and MRI capability improves tumor detection and delineation. Thus being able to see the specific area we want to target without harming other surrounding healthy tissues.
Upcoming virtual seminar 👇🏾 : Today Dr. Tanner (@EdenTanner) will discuss ionic liquids + nanoparticle drug delivery 🙌🏾 #Fascinating https://t.co/ypWSpCz0RO
Wow, I am just now realizing that none of my tweets went through 😩🤦🏾♀️ (Technology is hard) I will re-write them all tomorrow and try again. Let’s finish the week strong 💪🏾
The goal of my multi-modal nanoparticles is to give scientists and clinicians a novel cost effectiveness treatment for cancer #manifesting
Another amazing upcoming event 👇🏾 Focusing on cancer research, and community building + development! https://t.co/WP1JCYrnbR
👇🏾 https://t.co/PYvMd2H3Td
As I stated before, as scientists (and human beings) we tend to work nonstop. And when we do take a break, we tend to feel guilty about it. Let’s talk about the importance of health & wellness to finish the week.
We live in an age of unprecedented stress, yet few of us would consider taking time out to promote good mental health. We’re lead to believe that only hard work is productive. But I always say work smart not hard!
We stay so busy that we don’t have much time to think deeply (or broadly) about our work. While it might sound counterintuitive, taking breaks is an essential component of optimal thinking.
Don’t wait until you’re completely burned out to take a break. Schedule regular self-care routines (big or small).
Thank you to @MySci_PK & @RealSci_Nano It has been a pleasure curating for the week! Such an amazing audience 🤗 (great questions, great conversations) If you would like to continue to keep up with me (my work, my journey, etc.), follow me on twitter @O_Ganics
Additionally, don’t forget to listen to the full podcast👇🏾 https://t.co/7oiJssChOr
[admin] Thank you @O_Ganics for a wonderful week of science! Podcasts ft. Olivia are here - https://t.co/7KkTj2lhDb https://t.co/GQDkyoBfF8
Halan Mohamed
[admin] "Kidney-inspired Nano Brushes for Water Purification" Please welcome @HalanMX on @RealSci_Nano Listen to the podcast to know what is coming your way this week https://t.co/wlpv2VGQIi
Hello! Halan here taking over the page this week. I've got a lot of interesting science planned so I hope you're all as excited as I am 😊. Here's what you can expect from me 👇🏾 https://t.co/1egpXmNJtA
-A little bit about me and my journey into STEM -Nature under the lens: cool structures in nature and how (if at all) they're being used by researchers -Brushing up on functional polymers: my research on polymer brushes and their other equally cool uses
I also want to do Q&As throughout the week so if you have any questions about me or my work feel free to reply to tweets or DM me. I can post questions anonymously too so just let me know! https://t.co/Hmr32TsIwU
My journey started off many, many years ago in London where I was born and raised. My interest in science actually stems (pun unintended) from my year 2 (~6 yo) science classes where we would conduct experiments in class https://t.co/X45tsn3Yv9
I see science as a way of understanding the world around us & finding ways to change it for the better. Choosing to study chemical engineering as an undergrad was a natural choice. What better way to change the world than to the improve processes that influence our daily lives? https://t.co/ofHicgN0pv
I chose to do my PhD in ChemEng for the same reason. I wanted to help find new solutions to problems facing society. As idealistic as this sounds, research isn't always as *ahem* groundbreaking as we'd like it to be but every little helps, right? https://t.co/BgpZmvmXxQ
I am a final year PhD candidate in chemical engineering at UCL. I work on nature-inspired solutions to engineering problems, more specifically the "dirtying" (aka) of membrane filters in water purification
The natural(no pun intended) thing to explain first is what fouling is & why you should care. Fouling is essentially the accumulation of unwanted material on a surface (i.e. Plaque build-up on your teeth is a type of fouling & we all know how important it is to brush your teeth!) https://t.co/k2f8Hhu4Vt
Fouling is a huge problem in many industries ranging from medical implants to ships. Marine growth on ship hulls costs the US Navy $180-260M per year alone (Schultz, 2011). Fouling can be caused by organic(proteins, oils, bacteria etc) and inorganic substances. https://t.co/dYSfWBLojP
So my research aim is to make new materials with improved anti-fouling performance by fine-tuning their nanoscale properties
Welcome to my membrane 101 class: Membranes are essentially a semipermeable barrier used to separate things. They use different driving forces to achieve separation i.e. pressure, temperature etc. I work on pressure-driven membranes for use in water treatment https://t.co/shSRUO4qpm
Polymers are usually the material of choice for membranes. They can be formed in a number of ways including phase inversion, electrospinning and track etchting. The membrane here was formed using phase inversion https://t.co/pjoKY3cKUS
[admin] "Kidney-inspired Nano Brushes for Water Purification" Extended podcast ft. @HalanMX is here https://t.co/AVxPZuNGi1
So what would you like to see first for my first "nature under the lens" tweet? Suggestions are welcome too!
I would have loved to study geography! Fun fact: my geography classes had more of a role in my decision to study chemical engineering than chemistry or maths... https://t.co/gzqriNKjgH
My route has been a little unconventional, the idea for the project came from a post doc when I was doing my final year of undergrad. The work I did then was to test the feasibility of the idea which I've now developed into a fully fledged research topic https://t.co/raILuBaPO4
My supervisor gives us quite a bit of freedom to develop our ideas so I had free reign on how exactly I wanted to try and answer the research question (how to prevent fouling on membranes).
From my experience, this isn't the same for everyone, the norm seems to be applying to a predetermined research project. You can also propose a research topic but the issue then is usually acquiring funding for it.
This can vary country to country so it's also best to check. I hope this answers your question!
Shark skin is the very clear winner here! Stay tuned for this thread 😊 https://t.co/VYm52Q1GMY
There are two mechanisms for filtration depending on pore size. For larger pore size membranes (micro and ultrafiltration) rejection is size selective. Unlike cats, if it doesn't fit it doesn't sit https://t.co/us8tX9dEKw
Nanofiltration and reverse osmosis membranes reject based on the solution diffusion model. This just means that the solutes dissolve into the membrane and diffuse down a concentration gradient
As I mentioned earlier in the week, my research is inspired by nature, more specifically by the kidney. Why the kidney? Because it's capable of producing 180L of primary urine everyday whilst still remaining intact and fouling free. Warning: there's a lot of bio in this thread!
A quick refresher on kidney filtration: Filtration is carried out by nephrons, each kidney has roughly 1million of these units. Within the nephron there are two stages of filtration 1) Glomerular filtration 2) Tubular reabsorption (Labelled below, img: Wellcome trust) https://t.co/jytZs8Blvx
The first stage removes urea, ions (salts etc) and water from the blood stream to produce primary urine. The second stage selectively reabsorbs water and other small molecules that you need back into your blood stream
My work is inspired by the 1st stage which is a bundle of specialised blood vessels. The wall is made up of multiple layers (see left). The really cool thing about this structure is that albumin (protein ~4nm) can be rejected by the 1st layer even though the gaps are 100nm https://t.co/jxTCzCPkDP
Why is this so cool? With a pore size of 100nm separation should be based on size (see quoted tweet). This layer shouldn't be able to reject such a small protein but somehow it does? Amazing! https://t.co/DnGY6vTfcv https://t.co/Vwz0rxWlHJ
While there is no agreed filtration mechanism, my work looks mostly at how this system avoids the accumulation of plasma proteins and how I can adapt this for the application of water filtration. The most striking part is the hairy structure on top (see right) https://t.co/EsrtS00qc6
This structure is known as the endothelial surface layer. This layer is negatively charged and hydrophilic. This means that it can repel the plasma proteins (usually also negatively charged) and prevent adsorption by binding water within its structure.
The way that I've been applying this inspiration is by grafting polymer brushes which I'll delve into in another thread https://t.co/oZ6GUr57fO
My last thread was pretty heavy so let's take a bit of a breather. I'd love to know a little bit more about you all! Please pick whatever best describes you 😊
@holyoake_louise Thank you! I'm glad you think so too 😊
@RHammyOG No pressure huh? 😅
RT @DrDaramola: Good stuff. Bio-inspired physicochemical techniques are an excellent template for ChemEs. Just let us know when that "works…
The results are surprising! At least my "tweeterature" threads are less likely to be too content heavy 😅 https://t.co/kKb1xWxpCQ
Leading on from my nature inspiration in this previous thread, most of my current work revolves around the synthesis of polymer brushes. Polymer brushes are very aptly named, they're basically polymer chains that are tethered to a surface by one end like this 👇🏾 https://t.co/iXttYtYiPD
The two most popular methods of attaching these chains to a surface are: 1) Grafting to: premade polymer chains which bind to an anchoring site 2) Grating from: polymerisation of the chain from an initiating species on the surface https://t.co/gkFLkutvTT
Grafting from a surface is the most commonly used method. Different surface initiated controlled radical polymerisation (SI-CRP) techniques are used to graft these polymer brushes to create different (and all beautiful) polymer architectures https://t.co/YdW6jxsZIz
In a later thread I'll get into the different applications that polymer brushes are used in! Hopefully I'm starting to win you over about how cool polymer brushes are?
Polymer brushes have a very versatile portfolio. Flexibility over which polymer you graft can give you control over a material to make it: stimuli responsive (pH, temperature etc), compatible with different solvents, or further functionalised with desired compounds. https://t.co/h62W4Z4Xw7
Catalysis: Polymer brushes can be used as a way to immobilise catalysts. One example is the grafting of PHEMA-PEG brushes on the interior of microreactor channels to immobilise gold and palladium nanoparticles. Paper doi: 10.1002/chem.201000948 https://t.co/tM59cm6POJ
Energy storage: Polymer brushes can provide an elegant solution to incompatibilities between ceramic and polymer matrixes in energy storage devices (e.g. batteries, capacitors). When used as a bridge between components, the energy density can increase. https://t.co/moeFOvTuKU
Fuel cells: Polymer brushes can provide a platform to improve humidifying additives in proton conducting membranes. Silica nanoparticles modified with a polymer brush integrated into Nafion increased proton conductivity by 4x https://t.co/EoZbvPZPdK
Biosensors: Polymer brushes can be end functionalised with groups to aid specific adsorption of the biomolecule in question while preventing non-specific adsorption by others (aka fouling 😉) https://t.co/DMs6tDeIXS
These are just a few applications of polymer brushes. I'll post another thread on polymer brushes as anti-fouling strategies soon! So, polymer brushes, cool or not?
Just a reminder as we're reaching the end of my week on @RealSci_Nano! If you think of anything afterwards you can always find me on my twitter account @HalanMX 😊 https://t.co/5tOy5KpLAK
Is there anything you want to see from me before hand over the reins to this twitter account? Suggestions are welcome too! Poll in next tweet👇🏾 https://t.co/wvV6BpdreE
P.S. I've got a nature under the lens on shark skin coming up!
I'd like to talk about why I chose to sign up to curate this account As a Black Muslim woman it's not often that I come across people like me in chemical engineering research. I'm trying to do my part to increase the visibility and representation of those like me. (1/4) https://t.co/rNjzDzS76d
I usually tell people I fell into my PhD because I didn't have any real plans to do one. If it wasn't for my final year research project, I know that I probably wouldn't have ended up doing a PhD. (2/4)
Before I started my own journey in research I had a preconceived idea of who a researcher is and I didn't see myself fitting into it. I now know that my insights into life & engineering and thought processes are just as important in research. (3/4)
This is why I've spent a lot of time over the years doing different types of outreach. I'll always advocate for everyone to do more outreach/scicomm with young people because it's so important. Depending on time constraints I may post more about what I've done & some tips. (4/4)
So I'd like to talk about the most common anti-fouling techniques 1) Fouling resistance 2) Fouling release 3) Biofouling control The first two are passive methods to reduce the interactions between the surface and foulants whereas the third is an active method to prevent biofilms https://t.co/UoqPeUN2sG
1) Fouling resistance This scheme is the most common anti-fouling technique which aims to prevent attachment through the hydrophilic nature of the surface. The bound hydration layer makes adsorption thermodynamically unfavourable for adsorption https://t.co/iMwvIwH5eN
2) Fouling release In this method, adsorption is not being prevented, instead the surface is modified so that the strength of the interaction between the foulant and the surface is low. That way they can be easily removed. Low surface energy is usually the aim of the modification https://t.co/zvwwtzEJs6
3) Biofouling control The overarching aim here is control/prevent biofilm growth. This can be done in many ways i.e. using bacterial behaviour against them (quorum quenching), integrating biocidal elements into a matrix (antibiotic reagents, heavy metals) etc. https://t.co/QPY5d2mSyc
RT @realscientists: Growing up I didn't see anyone who looked like me that was involved with marine mammals (or any wildlife, really). I ha…
RT @MySci_PK: Representation matters!!
Polymer brushes as an antifouling technique! 🔊 So from my previous tweet you'll know the common antifouling strategies. Polymer brushes can be used to integrate one or more of these techniques to withstand adsorption of unwanted material. More examples below 👇🏾
1) Bactericidal brushes Quaternary ammonium salts (QAS) show antibacterial activity. By grafting with QAS the brush is capable of killing the bacteria that settle onto its surface. https://t.co/YR88j39miu
2) Biomedical devices The formation of biofilms on biomedical devices(i.e. catheters) can lead to bacterial infection. By grafting polymer brushes, initial adhesion of bacteria (up to 90%) can be avoided. https://t.co/Q856DDv88e
3) Contact lenses If, like me, you wear contact lenses you'll know that protein buildup makes them very uncomfortable. By grafting polymer brushes to improve the hydrophilicity of the lens (fouling resistance), protein adsorption can be reduced https://t.co/B6IMlrF5UU
DOIs for papers on these topics 1) 10.1021/ACS.langmuir.8b04187 2) 10.1088/1748-3190/aadcc2 3) 10.1016/j.surcoat.2018.08.078
By popular demand, this thread is on shark skin! https://t.co/MgbOaODQO1
Shark skin has a very interesting microstructure which has both anti-fouling and drag reducing properties. The features of this structure is in the micrometer range with 30-100um spacing and 200-500um in length https://t.co/Zm7Miqc9tB
How does it resist the settlement of bacteria? This relates back to my previous thread on anti-fouling techniques and fouling release strategies. The micro-pattern can reduce the available surface area for colonisation due to roughness, reduce the time for settlement due to... https://t.co/n6awKgwQPI
...the accelerated flow at the surface and the movement of the scales due to changes in pressure internally or externally.
Sharklet technology has provided a way to harness this property for applications such as wound dressing. This pattern has been tested with staphylococcus aureus, MRSA , Escherichia coli etc to show it's effectiveness across multiple microbes. https://t.co/RYfBREUVTf
Others have also built on this by not only utilising inspiration from shark skin but also building upon it to also kill bacteria. Through the use of photocatalytic titanium dioxide and nanoimprint lithography, surfaces which prevent settlement AND also inactivate bacteria. https://t.co/klewgNL43I
Well that's it from me folks! I hope you've all enjoyed this week as much as I have. Here's a highlight reel from my week of curation in case you missed anything Follow me on @HalanMX if you'd like to continue tohear more from me about research and my journey 😊 👋🏾 https://t.co/7jJuiUtAkv https://t.co/6Qhuy83sZw
[admin] Thank you Halan for a wonderful week of science! Do give @HalanMX a follow 🎊 Listen to the podcast to know more about Halan and her research - https://t.co/AVxPZuNGi1 https://t.co/B0vpZzzskM
Emma Wilson
[admin] "Shine Bright like a Nanodiamond" Please welcome this week's curator - @EmmRankinWilson Listen to the podcast to know what is coming your way - https://t.co/abGe3piZ2g
Hi #SciTwitter it’s my pleasure to be taking over the account this week! I got some plans for us, but if you have any questions or want me to cover something Nanodiamond 💎 specific let me know! (👇 Not a nanodiamond) https://t.co/54pDUYJJPo
My name is Emma, I’m a PhD researcher @CMBP_RMIT in Melbourne Australia. You can follow me @EmmRankinWilson. Normally I tweet pretty random things, some science, some #PhD & academia stuff, some #mentalhealth, some food and lots of Wilbur https://t.co/3VFwQf2TJO
This week I want to start with telling you a bit about my journey into #Science and #BioNanotechnology. Including working with @CNBPscience, I want to cover some opportunities and challenges of BioNanotechnology including working collaboratively https://t.co/Ot38NLlTpF
We'll talk about my #nanomaterial #Nannodiaomnds, what are they, and how do we use them? (Image adapted from DOI: 10.1002/ppsc.201900009 by @PhilippReineck et al.) https://t.co/sOYCt8NUzL
Later in the week, I hope to discuss some of the work I do in infectious disease diagnostic testing validation as a member of @NRLScience https://t.co/256qxVgrW4
And we'll wrap up with some Q&A and some general thoughts on Nanodiamonds in and where they might be headed. https://t.co/4Vj3oohHhy
https://t.co/Ngjw7R5bL7
So this is a bit I refer to as "My journey into Science, how a high school dropout became a PhD researcher - a story in three acts"... https://t.co/UhS7ef12fd
Act one, The Chef years: So I left high school, I wasn't very good at it, & some may have even considered me a trouble maker (but what do they know, right!). It wasn't that I wasn't smart (tho I had my share of people tell me that) I just really hated it! https://t.co/Ubhb8mAzjn
Quick sidebar - to all the high school students finishing up this year your worthiness to attend University is NOT solely found in your grades there are so many ways to get into the degree you want. Also, waiting a couple of years can be the best thing.
So when the opportunity came up to do a chefs apprenticeship, I jumped on it. I did 4 yrs of training & college, most of the time being the only woman in my classes. It had its ups & downs (mostly ups tho) https://t.co/eRAJyN5bny
I travelled the world, I learnt a lot about me and my capabilities, I worked with all kinds of people and developed some excellent core skills. It was a really great career I can totally recommend an apprenticeship! I mean, I got paid to learn and eat... https://t.co/7dHZ3x175H
...But I eventually started to want something different. I actually started to get pretty miserable working in the kitchen, I’d lost my passion for the food & the industry. SO I packed up my Knives and headed to University. https://t.co/WcXBdR3CTf
Act Two - Genes & Microbes & Proteins, Oh My! (the undergrad years)... Initially, I thought I’d get into Food science but I quickly realized that it wasn’t going to be my Jam. (Don't get me wrong it's a great field, I just needed not to be around food in that way) https://t.co/Ooc4VklCKs
After taking an intro to Genetics and Microbiology course I realized that I wanted to learn more about these subjects. So after chatting with the course coordinator I decided to switch my degree to the Biotechnology major.
I was in my element, I loved undergrad, & I got on really well with my lectures. So much so that several of them put me in touch with different jobs around Melbourne for me to get some work experience. https://t.co/x6WV5Px4xh
Another sidebar: Dear science UGs there are tons of opportunities out there talk to your professors, engage with them ask them for contacts. They want you to excel they are on your side!
Some of my professors put me in touch with job opportunities! this is how I got my first professional scientist experience in a Lab! I was awarded a studentship @NRLScience at the end of my first year... https://t.co/PCr17zs5kA
This role taught me the fundamentals of being a professional scientist and gave me a solid base to build on. It’s a project I’m proud to have been a part of and thankful for the experience (I'll talk a bit more about the NRL later in the week)
I also had a role @TheFlorey working with @Danscooter, this time playing with different variants of the Green Fluorescent Protein (aka #GFP). this is where I got hooked on things that glow, and how we use them as tools to study stuff like biology https://t.co/5WFRGhUa5C
So by this stage, I'm in my final year of undergrad & I was pretty sure I'd be graduating and heading out to industry. But someone suggested I give research a go by doing the honours year. So you would expect me to stay in molecular biology & study GFP, right?!
Nope not me, you see in 2nd year I met physicist @brantgibson, he had just joined RMIT & was heading up the RMIT node of @CNBPscience. Brant supervised me on a mini group project and well he was really fantastic. So when it came to thinking honours, I thought of him & the CNBP
So I emailed Brant and asked (SIDEBAR: always ask the worst they can say is not interested) Lucky for me Brant was happy to supervise me, & Brant was joined by @PhilippReineck & @VBansalRMIT to supervise me on a project looking at the #Nanozyme properties of #Nanodiamonds
At the end of my honours year, I was offered a job, but I decided to stay and do a PhD, I figured that if I didn't do it, then I probably never would. Also, Philipp had a juicy Nanodiamond project & the opportunity to continue with the @CNBPscience crew was too good to pass up :)
So I stayed... End Act Two (Gif text Stay tuned) https://t.co/b8DMl7MaJo
"My pathway to science - a story in three-acts" continued. Act three - The PhD and other scary stories 😉 Quick recap on Acts 1 and 2: I dropped out of school to become a chef, after 2-decades I dropped out of chefing to study science. They're actually not very different... https://t.co/RU0c1CcgAf
I started my PhD about 3.5 yrs ago, still working with Nanodiamonds, but now interested in the effect that nanodiamond particle size has on their interactions with biology and their fluorescence properties... https://t.co/UHT7oKPqL8
Ok so if that sounds interesting you are going o wanna stick around for this week as I cover the whole nanodiamonds thing in more detail... cos if a PhD researcher still finds their material interesting at this stage of the game the material must be pretty cool! https://t.co/Fu1xsQwcku
But, a PhD (well mine anyway) isn't just about the data & the thesis. I've been really lucky to have some fantastic opportunities, I've presented at conferences, done public outreach (My fav), & went to @Neurophotonics Frontiers in Neurophotonics summer school (highly recommend)
As a member of the @CNBPscience, an @arc_gov_au #center of excellence, I've had the privilege of working with & learning from some truly brilliant researches. I'll be including some of these people by @-ing them in my tweets this week & I recommend following or looking them up 🤩
I've had its ups & downs, & I think academia needs to work on some stuff. But at the end of the day, despite any problems I've faced I've not faced them alone. My supervisors always have my back, I'm truly grateful to @brantgibson @PhilippReineck @DoctaBlonde & @AmandaN_Abraham
So that is my journey from high school dropout to PhD researcher. I'd like to finish this intro thread-of-three-parts with this thought...
If you want to study something do it, but whatever you do do it with good people, kind people. They are out there & I hope to introduce you to a world of them over the coming week. We may study tiny things but we got a lot of heart to do it with. https://t.co/7oGccG2SDs
Anywho I hope my story might help someone realise that there are many ways to follow a career into science and all of them are valid and worthwhile. Tomorrow we're going to explore #Nanodiamonds, but right the other small monster in my life is demanding a walk https://t.co/EIJSWP6tZA
Today I want to discuss my nanomaterial, Nanodiamonds, they're not as expensive as you might think https://t.co/H5vW4TTsd3
When we think diamond we usually think of big shiny 'rocks' set in engagement rings or tiaras, and we typically think clear or colourless diamonds are the best. https://t.co/sCM4qkpRwN
But what is diamond really and is a nanodiamond the same as a the gemstone we like to adorn ourselves with? At the very basis of it, yes gems and nanodiaomnds are made of the same stuff...
That is to be called a diamond (whether regular or nanosized) it must be Carbon (C) atoms arranged in a crystal lattice structure. This structure is a face-centred cubic, each C bonds to 4-neighbour C's forming a regular tetrahedral structure. https://t.co/YHFTy3E2q7
Naturally formed diamond is the result of C atoms being pressed together under High-pressures and high-temperature (HPHT) within the earth. This process can be replicated in the lab to make the synthetic material I study, which is sometimes called HPHT Diamond. https://t.co/OFj8o04ZnI
Note: there are several different ways to synthesis diamond in the lab, including the HPHT method, CVD (chemical vapour deposition) & Detonation methods there are tone of great reviews on the diamond synthesis, I like this one focusing on nanodiamonds, https://t.co/p2Xheef5Qj
But any way you make it, the structure of the natural (mined) & synthetic (lab-grown) diamond are identical. But how do we make them nano? Stay tuned for the next part where I'll discuss the top-down and bottom-up approaches to creating nanodiamonds https://t.co/D9nQf1BoqG
@IreneSuaMar No pressure then 🤣😊, oh wait, 💎 needs pressure 🤔
Top-down synthesis refers to the process where we start with larger pieces of nanodiamond (ND) & make them smaller. E.g. we start with a micron-sized HPHT diamond &, crush it & then mill it to nanoparticles of diamond (NDs), similar to making flour from grains of wheat. https://t.co/BflF7mjQQo
Bottom-up methods include the so-called detonation nanodiamonds (DNDs) (yep what it sounds like). Carbon precursor is loaded into a chamber w/ an explosive (TNT). When the TNT is exploded creating conditions compatible with forming diamond crystal structure (see previous tweets) https://t.co/knR5S05Tge
Whether we crush or blow them into existence nanodiamonds ARD Diamonds (see TEM image). But they do have some key differences DNDs are typically <5 nm & have a more uniform shape. HPHT NDs are 10-100’s nm & vary in shape (image adapted from https://t.co/NDkvkB70HZ) https://t.co/OAoKm8j1M1
SideBar – for more details on top-down and botom-up synthesis see https://t.co/NDkvkB70HZ and for info on CVD methods see https://t.co/8QHc1DPyPp
I should add I don't make my nanodiamonds, they are commercially available from @AdamasNano. Also, I have collaborated with the Team at Adamas, but I am not paid by them there is no conflict of interest to report. 😊
He had a tough morning watching me work. So he’s taking a break. We could all learn some work-life balance tips from wilbur. By we I mean me. That said I’ll be back with more in Nanodiamonds this evening In the meantime feel free to ask me any Q! https://t.co/t1UACPdZlr
@astro_jje Same
I just came across this, it resonated with me so I want to share it with you all. Be kind to one another & one’s self as we transverse the 6 month crisis wall together. This too shall pass. ❤️ https://t.co/2XuFy2bM3Y
Sorry about the gap folks, my home internet has been patchy and I had work this morning. Are you ready for some info on the fluorescence part of my nanodiamonds? https://t.co/dLSzAgt8jf
The nanodiamonds I study are HPHT fluorescent nanodiamonds (FNDs), I’ve briefly covered the HPHT part & how we get nanosized diamond particles yesterday, but where do diamonds get the fluorescence properties? Gee, I’m glad you asked ;)
First Let take a look at a couple of my samples under room light…
My FNDs can be dispersed in water (handy for bio-applications). They aren't very pretty to look at under room light. The 140 nm particles look very milky. This is due to the highly scattering nature of the particles. As we go smaller the solution becomes translucent & darker. https://t.co/p29sw8WbB6
So what about this fluorescence I keep promising… https://t.co/bS8egnss7u
Well, Diamond, its self isn’t fluorescent, so I’ve not been exactly accurate when I say fluorescent diamonds. To get them to glow we need to create defects in the diamond lattice. https://t.co/8O9N3q83Ty
These defects occur in natural diamonds which gives then colour, e.g. if a carbon atom is replaced by nitrogen then the diamond will look orange, the most expensive nitrogen coloured gem is “The Orange” diamonds (a whopping $35 M). https://t.co/ApVO4eEOj4
Nitrogen-substitution is the most common colour defect in diamonds & in my nanodiamonds also. So we have the N which helps to give the diamond the orange colour, but to get the funky fluorescence we need one more thing… https://t.co/UFiHhlW7y4
Or instead, we need to remove something. We remove a carbon atom from the diamond, creating a vacancy in the lattice structure! The removal of an atom is done by firing high energy electrons & the material, (there are other methods, but my NDs use electrons)… https://t.co/FP2CWN84v3
The Carbon atom is “knocked out” leaving the vacancy. Then we need the nitrogen & the vacancy to be next to each other. Luckily heating atoms makes them want to dance & its energetically favourable for the vacancy & the nitrogen to want to be together. This is called annealing! https://t.co/i1Zyd8duX8
So by replacing a carbon with nitrogen then removing some carbons and heating the sample we finally get the fluorescent centre called the nitrogen-vacancy centre or NV centre for short. (Image from https://t.co/tuchTj1YJc) https://t.co/ryATZsjqQY
Now we need to excite the NV centre, this means we need to give the electrons of the atoms some extra pep to make them jump out of their ground state to the excited state & as they relax back down they give off some excess energy as a Photons https://t.co/Sd0HcR1e4d
That is a very rough quick explanation of Fluorescence… There are tons of great videos and books on fluorescence but here is an intro video that I like (they do lots of cool sci stuff) https://t.co/FDPweKhiM3
To excite the NV centre we use “green light”, we shine the green light (commonly 532 nm wavelength) and the NV centre will glow (Fluoresce) in the red & if we measure the emission spectra it will look like this (image https://t.co/u9qem55Kxc) https://t.co/ZfEUkzg2Pj
Notice in the spectrum, the two peaks labelled ZPL? This stands for Zero phono line. The NV centre has 2 ZPL because it can have 2-charge states, it can either have an extra Electron (NV minus [NV–] ) & No extra electron (NV neutral [NV0]).
So the NV spectrum is actually made up of two separate spectra, These charge states are part of what makes these types of fluorescent nanodiamonds (FNDS) so cool with a huge array of potential applications. (image https://t.co/u9qem55Kxc) https://t.co/AIr2FWAomL
The NV centre is sensitive to its environment so it can be used to sense things, like magnetic fields, temperature changes, & chemical changes. https://t.co/tFmW2RGEsE
Here are a couple of papers (see next tweet) if you're interested. If you have work in this field please add your papers here too. There is so much good work and I don’t want anyone to feel left out 😊. I’m all for shameless self-promotion
Just a sample of some of the work... Please add your own 😊 https://t.co/rfK2JMn7Gp https://t.co/b3VvzILuyB https://t.co/8HTEsBgbfF https://t.co/SlyGyJUf3M
So that's a little on the synthesis (yesterday) and the fluorescence of my Nanodiamonds. Questions? https://t.co/8tp6qFP1bX
@PatCapon Hahahaha Everyone this is @PatCapon he is one of my PhD cousins from @CNBPscience he is worth a follow for his #fluorescentFriday posts alone https://t.co/i89HEBU5zB
[admin] "Shine Bright Like a Nanodiamond" Extended conversation with @EmmRankinWilson is here https://t.co/CTS91Iwq21
@IreneSuaMar Good Q! I don’t think the NV centres, once formed, will move even if we heat the diamond again. At least not significantly. But there is research on using oxidation at high temps to remove surface diamond so that the NV in the “bulk” region are then close to the surface.
@IreneSuaMar Engineering NV centres is a really interesting field in its self. My PhD brother @MarcoIsTwitting studied The effect of Nitrogen concentration on the quality & quantity of NV centres in bulk (mm sized) diamond. I’d be curious to hear if he knows more on NV migration so to speak!
@IreneSuaMar Essentially yes, air annealing at high temperature burns off the outer layer. It’s also one way to remove amorphous or graphitic carbon from the ND surface as part of the purification process
So I know we are all about the nano here, but on my walk with Wilbur I saw someone had drawn the solar system on the lane way fence (unfortunately the rain got to it first) I love that someone was out doing guerrilla science in my neighbourhood 😍 https://t.co/4TbwmhdidQ
Ok I have to sign off for the night as I’m working on my sleep hygiene practice. But please please post any questions & I’ll answer them tomorrow over my morning coffee. So good night, good morning & good day #ScienceTwitter & #nanolandians https://t.co/49ucF6cNAL
@IreneSuaMar firstly, you're not silly or ignorant 😁, these are great Q! Size plays a big role in this, as particles get smaller the volume to surface ration decrease so the fraction of sp2 to sp3 (diamond C) does increase...
@IreneSuaMar also, diamond scatters light really well, as we increase particle size they scatter more light. So bigger particles ~100+ nm have less sp2 & scatter light so they will appear white (pale grey) and they will become darker as we decrease the size, more sp2 less light scattering.
@IreneSuaMar here are raw DND (detonation nanodiamond) powder it is Black (image from @AdamasNano https://t.co/B6YgBXwQKo) https://t.co/cU1mHvbLqC
@IreneSuaMar @AdamasNano this image is my material in water at 1 mg/ml, you can see how as the particles get bigger the solution becomes milky (mostly due to scattering). https://t.co/pr3R7uxiT2
@IreneSuaMar yep, these ones are very black, but when we make them fluoresce they shine very bright (well the ones that contain the colour defects like my nitrogen-vacancy centres) I'll show you all some images of their fluorescence over the next few days.
@Engineeringkate @engineer_nic I agree with Kate I got all my summer studentships (all paid) by asking my lecturers for network contacts and references
@MySci_PK This is @EmmRankinWilson for @RealSci_Nano this week I can tell you this is a lot of fun & there’s a really great community here. I recommend putting your hand up to share your nano science
@SnarkDivine I’m sure you feel worse about it than it was, that’s the trick of anxiety ❤️ talk with your PI & ask about stress management strategies. if you aren’t already seek a MH professional to help with your anxiety triggers. You got this you just need a little support ❤️
While I have a little time before I run off to do a tutorial I want to introduce you all to the Biology part of BioNanoTechnology. The past couple of days I briefly covered Nanodiamonds, how they are made & what makes them glow (fluoresce)
There are loads of great application research... but let's talk about some research that I think is interesting and to amplify some of the work that I think is really cool (yes some of these people are friends 😋) https://t.co/XFy8g4MGdY
First up let's talk about the work @Engineeringkate et al. Kate is a Biomed engineer who studies (amongst other things) Nanodiamond hybrid materials for medical scaffold's https://t.co/S4tQJosOdN
Kate et al. (2019) showed that by using nanodiamonds to coat 3D printed Ti (the stuff that makes hip replacements) Osteo- & Fibroblast cell growth was enhanced while bacteria (S.aureus) was inhibited‼‼ that is way cool. (image from https://t.co/hXfLHJ4Yev) https://t.co/RolrA90AV6
The potential to improve the health outcomes for people with prosthetic implants. S. aureus is a significant cause of post-operation infection if material like this can help to reduce infection it's a massive win for the tiny diamond. see https://t.co/hXfLHJ4Yev
Why I like this work is because it shows how much collaboration is needed to translate nanomaterials into a life-improving technology. This paper has engineers, physicists (both experimental and theoretical), biologists and chemists it's a huge team effort. https://t.co/HeBAj4ww3T
Please follow @Engineeringkate she is one of my favourite researchers and just all-round awesome human. If I was mad enough to do a second PhD, I'd do one with Kate
@AaronElbourne @MySci_PK @EmmRankinWilson Yes! Do it! Your Lab dose a bunch of awesome stuff you could all cover a few weeks I'm sure!
So I’ve had a really busy couple of days, and haven’t covered as much as I wanted. What I’d like to know is what would you like to cover this weekend?
Now let’s look at some fluorescence (Optical) based applications of Fluorescent nanodiamonds (FNDs), I discussed how the fluorescence of FNDs is actually from the Nitrogen-vacancy (NV) centre. & that the NV centre has 2-charge states, negative (NV-) & neutral (NVo)… https://t.co/M4dVOHze5F
The NV centre charge states are sensitive to change in their environment, so whether it is NV- or NVo can change, and this can alter the optical properties. Let look at an example of this… https://t.co/JIkQ8gXAzk
This research from Petrakova et al. (2015) combines DNA and FNDs (two of my things) & the following is from this work https://t.co/Jk4O3bZxkB
Inserting exogenous DNA into a cell is called transfection, think Gene therapy. And FNDs can be loaded with DNA and carry it into the cell & this paper shows a way to measure the delivery of the DNA using the NV fluorescence. Neat no?... https://t.co/ZQWt9URFgA
The negatively charged surface of the FND is coated in a polymer (PEI, commonly used in cell transfection) this makes the surface positive so now the DNA will attach to the surface & the FND@PEI@DNA NP are taken up into the cell where the DNA is released. https://t.co/D4UJIEc9ok
Changing the chemical charge on the Surface of the FNDs, first from neg to pos by adding the PEI, then back to neg with the addition of the DNA changes the electronic charge density … https://t.co/mvaLplqRXr
This is observed by imaging the NV fluorescence & looking at the change in the ration of NV-: NVo by a change in intensity of the ZPL peaks associated with the 2 charge states. As the DNA releases from the FND@PEI the intensity of the NV- peak decreases relative to the NVo peak👇 https://t.co/092xFoKNIX
This work is a cool demonstration of why the NV centre and FNDs used in a biotech application. they show this at work really neatly in a macrophage cell line. https://t.co/b2gvOfjIpQ
RT @MySci_PK: Will @RealSci_Nano cross 1500 this week? You tell me. https://t.co/axzkE1fCll
It looks like most people would like to hear about the validation of rapid tests kits… Why am I discussing medical devise validation testing on a Nanomaterials twitter acct?
Well, some of us are researching nanomaterials for medical devices & I think it's important to understand some of what it takes to get the device to market. Understanding the Standards & protocol for approval can help us translate basic research more effectively IMHO. https://t.co/BqyefEl3ZK
A few things first tho… I am not a medical professional, I am not offering medical advice! The following is aimed at providing some information about how a medical test is approved for use in Australia. https://t.co/eXlGcLR3wd
I’ll be covering some terminology & basic concepts I am not looking to get into a philosophical debate about the topics covered. Everyone is entitled to their opinion but I’m not here to discuss or debate them. I want to help clarify the process of medical diagnostic validation😊 https://t.co/E1zGltfI7A
Most of what I will cover is from the Australian perspective (this is what I know) & I’ll discuss some of the many regulations an entity must comply with to be approved to put a diagnostics out to the market.
Although I may mention COVID most of the info here is general & can be applied across the validation of different medical devices. I am NOT a medical professional this is NOT medical advice. https://t.co/essXT7Onnn
Due to COVID-19 the public is being exposed to more scientific terminology and concepts than ever before. This language can often be very jargony & difficult to penetrate. Even for those of us that work and study medical science, it can be a lot to get ones head around. https://t.co/MEfutpCZfn
things I see in the media a lot are the terms PCR test, antigen v antibody test, diagnostic V screening, Rapid versus gold standard test. But what does all this mean in practice & what are the key distinctions?
Firstly, Diagnostic V screening: a diagnostic test is one that confirms someone's disease status, either that they are positive (have the disease) or are negative (do not currently have the disease. https://t.co/vzmIEfFFYb
A screening test is less certain, it indicates that someone may have the disease. typically screening is used when the risk is low or if their status is already confirmed positive & we want to know how they are responding to treatment.
Whether the test is classed as diagnostic or screening will typically depend on its sensitivity and specificity. Sensitivity = how much of the test target (e.g. infection) needs to be present to show up in the test Specificity = do the tests only detect the test target https://t.co/wT8NHSoU0Y
how sensitive or specific the test must be will depend on the disease it is testing. One disease may need the diagnostic to 100% sensitive & 99.5 % specific, while another could be 95% sensitive and 98% specific.
PCR – Polymerase Chain reaction detects nucleic acids (think DNA) here is a great vid explainer 👇 https://t.co/1NG0VPZ3iU
An antigen (Ag) is a foreign or toxic substance that triggers an immune response they can be specific to a single species or common amongst a class of organisms. So an Ag test detects the presence of the infecting organism or its antigenic proteins.
An antibody is a blood protein that your cells produce in response to an antigen. They bind the antigen to help the immune system to clear the antigen from the body.
This video from https://t.co/KAClIKJQZm is a quick explainer of the difference between these tests. Note: there are now available Antigen tests of COVID-19. this vivid is 4 mths old, but it shows how quickly the technology is moving to help combat the current global pandemic
The "gold standard" test typically refers to the legally approved method for diagnosing a disease. e.g. In Australia, there are 3 approved methods PCR - nucleic acid detection Rapid Antigen test Serological test
Note: although the newly approved Antigen Rapid test is classed as diagnostic all positive tests must be confirmed by the PCR test before being added to our COVID numbers. This practice is pretty standard in Australia for infectious disease rapid diagnostics.
All these terms, concepts and practices are strictly defined in documents called “Standards”, in Australia we used both Australia Standards (AS) & International standards (IOS). A Standard is a legal document that defines & outlines “best practice”.
By using Standards, we help to ensure practices, like diagnostic tests are comparable from lab to lab. this is all highly regulated in countries like Australia and is partly why we have good reliable health care. https://t.co/rXOPdnOnW1
Approval of medical devices (e.g. test) is governed by an official agency, in Australia, it's the TGA (Therapeutic Goods Administration), in the USA the FDA (Food and drugs Administration) & in Europe the EMA (European Medicines Agency).
For Australians, the TGA website is a great source of COVID testing information so if you want a deeper understanding please go there https://t.co/cVsWRdrHLF for other countries & regions see your own governing bodies for relevant information
A rapid diagnostic test (RDT), simply is a test that is faster than the existing gold standard. E.g. for bacterial infection PCR is classed as an RDT, the gold standard for diagnosing bacterial infections are biochemical tests that can take up to 10 days for the diagnosis.
In cases were PCR is now the “gold standard” an RDT could include an antigen test such as the one recently approved in Australia. Also in Australia Diagnosis of a disease can only be done by an approved lab using one of the approved methods.
Next, I’ll give a general walkthrough of what we do in a medical device evaluation @NRLScience without going into specifics because we deal with IP and confidential material. I just want to give you an overview of this challenging but rewarding line of scientific work
Evaluation of a proposed Rapid diagnostic test (RDT): This evaluation can only be done by an approved lab with trained & qualified staff. For example, I recently joined a project to validate some RDTs, I have undergone intensive training, down to my competency to use a pipette. https://t.co/xNopR5fvfv
The process of making sure an RDT works as the manufacture says is heavily regulated. Each step & protocol is controlled, in fact, @NRLScince has 700+ controlled documents that we used to ensure we are compliant with the different entities we work with. https://t.co/F1TleNLD7s
They tell us how we are to conduct each task, although we don't need to know all of them. Some will be for tasks that I don't do. And I can look up the documents I need any time I need to refer to them.
Let look a one way we might run an evaluation for an RDT. Say a company wants to get their new RDT out to market – they have tested it and are confident in the test, but they need to have it validated by an authorised & independent lab, such as @NRLScience.
Once the contract is agreed and the goals and parameters outlined we get to the practical task of testing the test. the example I'm giving here is for subjective tests, think pregnancy strip. Do I see a line or no line, Do I give it a 1 or a 3 etc.
We receive the RDT & assemble the test samples, these include controls & reference samples – a ref sample is a sample that has been tested using the gold standard & its status is known. All samples are randomised & the work is done blind (testers don’t know the sample status)
In my current role 3 of us work together so we can triple check our work. We then run the test according to the manufacture's protocol. The aim is for us to follow the test as it would be done by someone in the real world. We check the quality of the kit... https://t.co/U62nXrFmcn
We may also make notes on the ease of use, e.g. if the manufacture says the test could be done by someone with no scientific or medical training do we agree, are the instructions clear & easy to follow. These points are subjective that's why we have multiple people. https://t.co/A1BdwiKxhF
We run the test, this involves 100’s of samples over multiple manufactures Lots (different batches) of the RDT, this way we can see if the manufacturing quality is consistent from lot to lot... https://t.co/vmtHWV21fA
It’s no good if one Lot is 100% sensitive & 99.9% specific if the next lot is only 90 % sensitive. The RDT must perform the same (within a very narrow range) test-to-test and lot-to-lot. https://t.co/Sb2Lel9CEg
We then interpret the result, and check if all 3 of us are in agreement (again this is for a subjective test). 2 out of 3 of us must agree in our interpretation of the result, i.e. is the sample positive or negative?. If we don’t reach consensus the test is redone. https://t.co/ymmjbNnsqy
you need to be confident in your evaluation, it's really important once we start that my grading scale is consistent from our first run to our last. And that I don't let my colleagues change my opinion on what looks like a positive V a negative to me. https://t.co/AkvGyPHFSG
We take detailed notes on each run and even take photos, we need to be scientific as possible and evidence must be given at the end of the evaluation. There are even regulation on how we write our notes 😳 https://t.co/Ztw1obh1ZP
This work is highly repetitive and we must do it methodically so breaks are important so we don’t get fatigued & make errors. We follow a work instruction, it's a little like doing a pre-flight checklist & excellent verbal communication is vital. https://t.co/jolrhRU9cc
This work is not for everyone, it requires focus & an eye for detail and an ability to follow a check-list and do a repetitive task the same again and again. It costs the manufacture a lot of money & lives might depend on us doing our job right. This is a lot of pressure. https://t.co/YEuPFBdprd
But, it is very rewarding knowing that you are contributing to work that can help improve health outcomes. https://t.co/cO9iZIRBCZ
If this sounds like something you might find interesting & you are coming to the end of your science degree wondering what to do next. Jobs in evaluation come up often. Even if they don't have jobs listed it can be worth reaching out. Some labs will have studentships too.
So that was a general overview of RDT evaluations prior to approval to go to market. let me know if you want more detail about anything I've covered and I'll do my best to answer your questions 😊
Today is my last day on @RealSci_Nano so I’d like to talk about my experience and opinion on the future of nanomaterials. https://t.co/7DVhfkk6sV
Nanomaterials are really cool and there is lots of exciting research aimed at understanding them and how to apply them. From industrial applications, thru to quantum, computing and data storage, to biological & medical application, there is something for every scientist.
I think that's why I love nanomaterials so much, they have such amazing potential to affect all aspects of our modern life. But, #Nanomaterials science is such a new field, couple this with the diversity of materials and the potential application to be explored… https://t.co/0LRepaYd6B
I think it’s really important that we clearly communicate not only the potential but the limitations of our respective materials. Limitations do not invalidate our material, limitations are inherent in all technologies. https://t.co/IMCf00QuWO
ALSO if we are open about the limitations we invite others with different expertise & perspectives to join us, people who may actually have a solution or workaround for the limitations or challenges of our material. https://t.co/7aEuFU5JQf
Collaboration, across different scientific fields, is the key to studying #Nanomaterials. At the @CNBPscience over the past 7 yrs, we have been working on our ability to work effectively with those outside our respective fields...
Chemist, physicist, biologist, engineers & Clinicians working together. IF you would like to hear more about the @CNBPscience journey & approach to successful communication between scientists go to our legacy website https://t.co/xIHVdUDfLV
@AsantewaaDarkwa I second this
Wow, what a great week, thank you all for your engagement & I hope you enjoyed #MyScienceStory & #Nanodiamonds. This has been a great experience & I've found some fun new twitter friends 😊 Please come visit me over @EmmRankinWilson https://t.co/s3RoqvvovP
[admin] Thank you @EmmRankinWilson for a wonderful week of nanodiamonds and more. Do give her a follow! Podcasts ft. Emma are here - https://t.co/CTS91Iwq21 https://t.co/luXWSaf9IP
Rajesh Ramanathan
[admin] "Sensing & Killing Bugs - the Nature-inspired Way" Please welcome @DrRajeshRMIT and listen to the podcast to know what is coming your way this week https://t.co/Ew3xeaDP0w
Hi #TwitterWorld and #ScienceTwitter - It is my pleasure to curate the @RealSci_Nano account this week. During my curation week, I am going to give all of you an overview of the work we do at @RMIT_NBRL. Please feel free to post any questions 🙂
A big thank you to @DrTinyTaps for nominating me!
Here is what I have for all of you this week. I will start with my academic journey (everyone has a unique story) The next few days I will talk about some exciting work we do at @RMIT_NBRL in the area of #nanozymes #sensors and #microbialmanagement.
We celebrate 1 year of this account on Oct 1 - I will introduce the @NBRL_RMIT group members. Friday will be focused on the challenges we face with #COVID & how we can use our time productively. I would like to engage with all of you and learn from each other.
Over the weekend, I would also like to talk about how I have used teaching as a platform to engage with students and tell them the importance of research. How we can inspire the younger generation!
Academic Journey # 1 - After hearing about #Biotechnology from a close family friend, I decided to pursue a Bachelors degree in Botany and Biotech. Was not an easy task to convince my parents as #biotech was new in India at the time and not doing #Engineering was a crime
Academic Journey # 2 - I moved to #Australia to do my Masters @RMIT. Loved every bit of my research project in #Bioinformatics. Worked in the #industry doing #ClinicalResearch for few years.
Academic Journey # 3 - Thanks to Peter Smooker who introduced me to @VBansalRMIT. He introduced me to the #nanoworld. People often ask - what factors did I consider before I chose my PhD project. I chose my mentor (not the project!) - the best 3.5 years
Academic Journey # 4 – After my PhD, I spent time at @UMassAmherst with @RotelloGroup. I came back to @RMIT with a #ViceChancellorFellowship and started to co-lead the @RMIT_NBRL group.
Some non-academic interests - #readingnovel #photography #writingpoems #guitarplayer #Singing #trekking #travelling and off late #running
Today we had a quick overview of my journey into the ‘nano’ area. Tomorrow we dive into the fascinating world of #nanozymes https://t.co/uL0k7akGW2
A big yay! The @RealSci_Nano has reached 1500 followers :)
Time for some information about #nanozymes. The word NanoZyme comes from two words - NANOparticles and enZYME. A nanoparticle is called a nanozyme when it can mimic the catalytic activity of a natural enzyme. https://t.co/QyHGYJJ2VG
This is quite fascinating! To think of it - an inorganic particle which does not show structural similarity or the complex folding patterns of a natural enzyme can still drive the same catalytic reaction to completion as seen in a natural enzyme.
As a biologist, the first curious question that comes to mind - if the complex folding plays an important role in the activity of natural enzymes what is the driving force in nanozymes?
It is the surface atoms in nanoparticles that play an important role in the catalytic activity
Next obvious question is why do I need nanozymes? Natural enzymes are temperamental and difficult to work with. Let's be honest no one likes that :) NanoZymes are easier to work with, we can fine-tune the activity, and are robust.
It's not all positive for nanozymes - believe me. As amazing nanozymes are - we have not been able to achieve the high level of specificity and complexity we see in natural enzymatic systems. I talk about this in my biochemistry lectures https://t.co/ngeSx8oB0E
For anyone who knows the concepts of Km and Vmax - you can ignore this post
Compared to natural enzymes, nanozymes are sometimes better for their catalytic activity. How can we compare this?
There are two factors we consider to compare enzyme and nanozyme - how much the enzyme loves its substrate (Km) and how fast can the enzyme convert the substrate to product (Vmax). https://t.co/xBOSVX8AfK
A simple analogy for this concept is your car (body), engine (enzyme) and fuel (substrate). Km is like your measure of fuel efficiency. The less fuel you need the more efficient your car is. Vmax is the fastest speed that you can drive at. So you need low Km and high Vmax.
Many of us have heard of an enzyme horseradish peroxidase (HRP). If I was to compare the peroxidase activity of this enzyme with nanozymes with respect to Km and Vmax, let us see what we get
Woah! We can see some of the nanozymes are a lot better than HRP. Isn't this amazing. Although it took a lot of time to get to this point, it is great to see the performance of nanozymes keeps getting better. https://t.co/K8wun8Uj6v
@avpoltral Lol. I still remember reading about enzyme kinetics as an undergrad student. Never thought I will ever use this in my career and here I am sitting and analysing kinetics data.
An interesting fact about nanozymes # 1 - I heard that the first report on nanoparticles showing enzyme-mimic activity was a serendipitous discovery. This is something that we see a lot in research. Opens up exciting possibilities.
An interesting fact about nanozymes # 2 - We have been able to mimic the catalytic activity of peroxidase, oxidase, catalase, haloperoxidase, glutathione peroxidase, uricase, methane monooxygenase, hydrolase, superoxide dismutase and pan-enzymatic activity. That is a lot.
An interesting fact about nanozymes # 3 - We have a new field today called Nanozymology
An interesting fact about nanozymes # 4 - The word nanozyme was only coined in 2004.
Let's play a game. Can you guess how many papers have been published this year in the area of nanozymes (don't worry about researching this - just take a guess). I will give you the answer tomorrow.
If you have a question about any of the posts, do feel free to leave a comment or send me a message directly -@DrRajeshRMIT. I will get back to you as soon as possible.
OOO looks like >400 is winning as of now. Let us see how we go.
We had some fun today looking into #nanozymes. Tomorrow we will focus on how we can use nanozymes for sensing applications.
[admin] "Sensing & Killing Bugs - the Nature-inspired Way" Extended conversation with @DrRajeshRMIT is out now https://t.co/GdOwmvObXO
Yesterday we got to see how fascinating #nanozymes are. We even saw that we can apply biochemical principles we use to understand natural enzymes can be applied to understand nanozymes as well. Today we look at how we can use nanozymes for sensing.
Yesterday we ran a poll trying to guess how many papers have been published in the area of nanozymes. The answer is...
wait for it
wait for it
Over 400 papers have been published just this year. So congrats to everyone who selected that option. https://t.co/U2vCbS4GQR
Before we dive into how we can use nanozymes in sensor development, there is something we need to know. For a sensor to be able to do its job, we need something that will recognise our analyte of interest in a complex sample matrix
Sample matrix - this will contain a mixture of substances. For e.g., if I want to detect a pesticide, it may be present in the soil or on the surface of a fruit, which will contain a lot of unwanted molecules including other pesticides.
You need something that will specifically identify your analyte of interest. It is like finding a needle in a haystack.
We can use antibodies, enzymes, proteins, lectins, carbohydrates or aptamers. Traditionally, we have focussed a lot of work on antibodies. In our work, we use aptamers to specifically bind to our target.
Lets first look at what is an aptamer. Aptamers are oligonucleotides or peptides and bind to their target analyte with high affinity. For instance, a DNA aptamer contains single-stranded DNA containing anywhere between 20-60 nucleotides.
This single-stranded DNA will fold and create a unique 3D structure that will then recognise its target. A very effective molecule to recognise its target. https://t.co/BiatWSWjyu
But why not just use an antibody? Aptamers offer better target discrimination, have lower batch-to-batch variability and in many instances have higher specificity towards its target. They are also easier to store. I say if it's better why not use this instead of an antibody
Yesterday we saw that a nanozyme can catalyze a reaction similar to natural enzymes. Now we will see how we can combine aptamers and nanozymes.
When we expose aptamers to a nanozyme, the aptamers bind to the surface of the nanozyme. In this process, they block the surface atoms. This results in the nanozyme to lose its catalytic activity.
Remember how we said that aptamers have a very high affinity to their target?
If we now expose the aptamer-nanozyme complex to a solution containing a target that the aptamer recognises, they will dissociate from the surface of the nanozyme and bind to their target.
When aptamers dissociate, they expose the surface atoms of the nanozyme. This means, the nanozyme now regains its catalytic activity.
If I expose the aptamer-nanozyme to a solution containing a target that the aptamer does not recognise, they will not dissociate from the surface of the nanozyme. This means the nanozyme will still be inactive. The figure here is quite useful to understand the concept https://t.co/E9w92k6Xjd
This simple yet effective strategy has helped us develop sensors to detect pesticides, an antibiotic, and even a whole virus.
Here is the links for virus detection (https://t.co/KImIVxjIXw)
Here is the link for pesticide detection (https://t.co/9KYDFWDcwL)
Time for another quiz today. Yesterday we said nanozyme was a serendipitous discovery. Can you guess which nanoparticle was the first to be reported for its ability to mimic the natural enzyme?
One of my mentors told this to me once - A concept should be simple to understand. This means more people will appreciate it. Simple does not mean your science is less effective. I admire my mentor for telling me this. #Mentorship
Wishing @RealSci_Nano a happy first birthday :)
Ooooo looks like a lot of people voted for gold nanoparticles in yesterday’s poll. But the first report of nanoparticles showing enzyme like behaviour was - iron oxide nanoparticles. :)
So yesterday we saw how we can combine the strength of nanozymes and aptamers to create aptasensor platform. A simple yet effective tool to create a sensor.
Today we look at how we look at combining natural enzymes and a nanozyme as well as a protein and nanozyme. Let's look at combining natural enzyme and a nanozyme
In this example, we will look at the detection of urine glucose. We all have heard of diabetes. It is a disease that causes high blood sugar. If you have suffered from diabetes for a long time, it can lead to renal complications.
Interestingly, we have blood glucose monitors that are portable and easy to use. However, they do not give you any information about renal complications. We decided to address this.
We had a particularly challenging problem. The concentration of glucose in the urine is quite high - generally in the millimolar range. You see - we always had sensors to look at low concentrations. So the challenge was now to develop a sensor to look at high concentrations
Instead of using nanoparticles directly, we embedded them in a piece of cotton fabric. WHY? Two reasons - (i) we can load a lot of nanoparticles and (ii) cotton being an absorbent material, it will bring the glucose in close proximity.
What was the recognition element in this case - easy - we used the enzyme glucose oxidase. This will specifically convert glucose to form hydrogen peroxide. This is the key. The hydrogen peroxide is one of the substrates for the nanozyme.
Before we go away, one last concept about how we can combine proteins and nanozymes. Yesterday if you recall, aptamers and nanozymes interact in a dynamic manner. That means, the aptamers can move from the nanozyme to bind to its target.
We found that this approach did not work in some cases. Don't you hate it when that happens! But we came up with an alternative approach. This is an example where the nanozyme activity is always ON.
Let's see - we now have a protein called transferrin. This protein will specifically go bind to cells that have a transferrin receptor. The probe in this case is the nanozyme-protein conjugate. However, unlike yesterday, the nanozyme activity here is still on. https://t.co/SICHk0WmXL
If I mix some cells with this probe - say some specific type of cancer cells that have transferrin receptors. The transferrin protein-bound nanozyme will now go bind to these cells. If the probe does not find transferrin receptors they will be free.
If we isolate the cells and wash them now - the free probe is gone. What we are left with is just the transferrin protein-bound nanozyme tightly stuck to the transferrin receptors. If we now do the assay, we get colour. Isn't this cool :)
We actually didn't just stop there. We also showed that this strategy can be used for receptor profiling - Oh sciency words. What I mean is I can look at how much transferrin receptors are produced by different cells using this :) https://t.co/gnjqC8p4a9
For anyone who is interested in this - have a look at https://t.co/TqauIIfVyJ For anyone who is interested in the glucose-sensing - have a look at https://t.co/cFmuz7GyIy (and a new one to be published very very very soon!)
Tomorrow we look at how to kill some bugs using nanozyme!
@NotHF So true! Fenton reaction at its best :)
Today we look at how we can kill bugs using nanozymes. We also look at how we can use light to enhance this process. https://t.co/8Tg1vSgKTb
The first one we will look at it just using a nanozyme without light. We already know how we can use a nanozyme to convert a colorless substrate to a colored product. One of these substrates is H2O2. Nanozymes convert H2O2 to form a very reactive species called OH radicals https://t.co/ScYR5hvPXL
This radical targets the integrity of the bacterial cell - if the bacterial cell membrane is destroyed then the poor bacteria does not survive. Well the process is something like the one in the gif https://t.co/oiPwuroTFF
What does light have to do with the concept of nanozymes? Well, we know that nanoparticles interact with light. This leads to some interesting properties. Look at the GIF of the Lycurgus cup made in the 4th-century made by the Romans. https://t.co/YqTyMpE96Q
It changes color as it has gold and silver nanoparticles embedded in the glass. This results in the change of color depending on where the light source is. We use the ability of nanoparticles to interact with light.
We saw that nanozymes can convert H2O2 to OH radicals (post in the morning). In that case, if the nanozyme is given 4 H2O2, it only converts one to OH radical. If we shine light on the same nanozyme, it will convert all 4 to OH radicals. https://t.co/ugGB6Q05O6
This means more killing of bacteria. :) It is important to remember that the light source to be used will be determined by the nanozyme composition and nanozyme morphology.
Here is the work from the group where we have used visible light to improve the killing of bacteria. https://t.co/Sligcvxf4h
What we show here is that light not only improves the affinity of the nanozyme to H2O2, it also improves the catalysis by 20 times. This is just an example of how we can use nanozymes to kill bacteria.
Has been quite a week with a lot of information about nanozymes. But isn't the concept fascinating? :) Tomorrow, I want to introduce you all to all the group members who do such an amazing job. Catch you tomorrow. Happy Friyay :) https://t.co/n74PYDfEU3
Meet @sanjananp - Her work focusses on developing nanozymes for sensing applications. Remember I spoke about glucose sensors on Thursday? She was the one working on this aspect :) https://t.co/9DPYlYrNPg
Meet @piyumi_RMIT - Her work focusses on understanding how we can modulate the interaction that aptamers have with nanozymes to make sure we can get ultra-sensitive sensors. https://t.co/nJ1xh27tIt
Meet @PabudiW - She is a Postdoctoral researcher who was one of the first group members to work on the nanozyme concept. It has been over 6 years since then. And welcome to the youngest member of the @RMIT_NBRL family :) https://t.co/tQfB9xh7Ub
Meet @HashmiSabeen - Her work focuses on the fundamental understanding of biomolecular interaction with nanoparticles. Was a challenge to get this photo as she doesn't like her photo taken. :) https://t.co/aPDJXe2DpZ
Meet @dancing_toxico - Gayatri has been working with us for the past 6 months on developing nanozyme-based sensors for Parkinson's disease. https://t.co/yeRfis8qd7
Meet @PyriaThomas - Pyria has been exploring - how we can use nanozymes to kill bacteria. Some of the work I presented yesterday was done by Pyria :) https://t.co/pk7eJaD7kF
Meet @MSingh_RMIT - Mandeep is a postdoctoral researcher who is an expert materials chemist. You want to talk about materials - he is your guy :) https://t.co/bjiWCsIvpd
Meet @Dr_WenyueZOU - Wenyue is a postdoctoral researcher working with us. She is a rising superstar who has done some amazing work on UV sensors. https://t.co/JZgEBQbGqi
Meet @avi_ingle - Aviraj is working on fabricating interesting 2D materials and looking at their optical properties. https://t.co/jnebxLyoVi
Meet @Oshadie_RMIT - Oshadie works in the area of water splitting. She is exploring interesting properties of nanomaterials to improve the efficiency of water splitting catalysis. https://t.co/KL9NF5xN0h
Meet @Zzakir_Hussain - Zakir works in making organic semiconductors for catalysis applications. https://t.co/I4fXFLPFPn
Meet @MahasivamS - Sanje is focussing on controlling where on a single nanoparticle should the catalysis occur. https://t.co/JzGtFXt0Eq
Meet @hira_sat - Satnam is working on making magnetic nanoparticles for biomedical applications https://t.co/KhKiwwSqCl
Meet @SamAndersonRMIT - Sam's work focusses on embedding nanoparticles within interesting templates. Remember how we spoke about incorporating nanozymes in fabrics. Sam is the man who achieved this. https://t.co/honzFR14sz
How can I forgot - last but not the least - Meet @VBansalRMIT - he has been my mentor since my PhD days and I can't thank him enough for the role he has played in my life. https://t.co/e8S1tNeArw
There are many other people who work in the group but not directly with me. Do give @RMIT_NBRL a follow if you would like to know more about the exciting work the rest of the group does.
What a week it has been - we looked at how nanoparticles mimic the catalytic activity of natural enzymes - we call them nanozymes; how we can use nanozymes to develop sensors to detect small molecules to cells and also how we can use them to kill bacteria.
Yesterday we had the opportunity to meet the amazing young researchers who are part of the @RMIT_NBRL group
Today I want to deal with something we are all going through - COVID. I was just having a chat with my wife about how things are different now - we don't go to conferences anymore, we don't get to see each other, networking is down to people we know.
This led me to think - When I was a PhD student and an early career researcher - what was the thing that helped me the most? I could only think of one thing - networking, networking and networking.
Networking helped me to know researchers working in the area, made some amazing friends, ideas were exchanged, developed new projects, even submitted grants with some of them, got to understand how research works in different countries - I can keep going with this.
With COVID how can we help students and ECRs to get the same level of exposure? In my mind, I think organising conferences within the department across the university or even have conferences with just two universities. It helps them with confidence and introduces new people.
Encourage students to attend virtual conferences - I know it is not the same but none-the-less useful.
Have departmental seminars where someone external to the university presents. This way students are exposed to work outside their university.
Encourage students to join Chemical / Engineering professional organisations - attend their events - generally, they are cheap or free for students - helps with networking (you never know - you may find your potential employer)
Introduce your collaborators to the group or have their students present their work once a fortnight. Helps them with interacting with researchers not directly associated with their work and will improve their perspective
I would like to know what has helped everyone else during their PhD and post-doctoral career that they think the younger generation is missing out on due to COVID and how we can address this. Comment on the post and share your ideas. Would love to learn!
It has been a pleasure sharing my work with all of you. A big thank you to @MySci_PK for giving me an opportunity to curate the @RealSci_Nano account. Do give me a follow @DrRajeshRMIT if you would like to know more about the work we do or for collaboration or just a chat! :)
I am glad to have had the opportunity to curate the @RealSci_Nano account when we celebrated its first year birthday and we reached the 1500 follower milestone. Looking forward to the next curator.
[admin] Thank you @DrRajeshRMIT for a wonderful week of science! Do give him a follow! Podcasts ft. Rajesh are here Short - https://t.co/Ew3xeaDP0w Long - https://t.co/GdOwmvObXO https://t.co/BXCDKdF93W
Antonija Grubisic-Cabo
[admin] "Supercool Electrons in 2D Materials" Please welcome this week's curator - @CaboAntonija Listen to the podcast 👇 to know what is coming your way https://t.co/aAZNF9QSII
Good morning (afternoon/evening) everyone! ☕️ This is Antonija @CaboAntonija , I'll be taking over the account for the week. :) If you saw the podcast, you know there is a lot I want to share with you, mostly related to 2D materials.
Today, I will mostly focus on how I got here and how my typical day looks. Stay tuned!
As a kid, I was A HUGE Star Trek fan, I grew up on Star Trek Voyager, and I really wanted to go in the #astronomy filed. By the way, did you know that there is an @edXOnline course on Star Trek given by the Smithsonian theat's even free to follow? @SmithsonianX #StarTrekCourse
@DrJenMacLeod @CaboAntonija Thanks, I hope it will :)
I studied physics at the University of Zagreb in Croatia, even took a couple of astro courses. But somewhere on my 3rd yer of undergrad, I really got into condensed matter physics and #magnets, so I ended up getting a masters degree on a topic of quasi-zero dimensional magnets 🧲 https://t.co/nBtX9iA4j6
If you are interested in what the "quasi-zero-dimensional" magnetic systems do, you can check out my paper on the SeCuO3, which was the topic of my masters project with Dr. Mirta Herak at the Institute of Physics in Zagreb https://t.co/zxOYBpBXXo @PhysRevB
At the end of my masters, there weren't really any openings in the field of magnetism, but luckily, my supervisor's colleague knew of a PhD project on #graphene in a group of Prof. Philip Hofmann @AarhusUni
At this point, I didn't know much about graphene, except that it is super cool material 😎, but I liked the project and the group, so I decided to move from Croatia to Denmark, and study graphene and #nanoscience at the interdisciplinary nanoscience centre iNANO @iNANO_AarhusUni
Going to the lab now, but will continue in the afternoon! :)
During my PhD I got to work with a lot of great people at @AarhusUni on different #graphene and 2D material projects. I also got to do experiments at different user facilities across the Europe, such as @MAXIVLaboratory , @elettrasincro and @STFC_Matters
Most of my work was on graphene growth and angle-resolved photoemission spectroscopy (ARPES) and time-resolved ARPES. I also did a bit of scanning tunneling microscopy. All of these techniques are done in ultra high vacuum (UHV).
After my PhD I moved to @MonashUni where I worked at the School of Physics and Astronomy @MonashSci . I was mostly working on scanning tunneling microscopy (STM), a technique used to image #atoms. At Monash, I got to work with a lot of great people from @FLEETCentre
My work was still on graphene and other 2D materials. I also got to do experiments at the Australian Synchrotron @ausynchrotron in Melbourne and Advanced Lightsource in Berkeley @advlightsource . One new thing I learned is also how to use a cleanroom @Nanomelb
After almost 3 years in Melbourne, earlier this year I moved to KTH in Stockholm. I am now working again with time-resolved ARPES and I am helping up in setting up a time-resolved lab. It means you need to use both UHV and #laser skills 🙂 https://t.co/o8vmRqiFMR
As we are still setting up the lab, a lot of my daily work is spent with the setup. We are either aligning the #laser, or working on getting all of our chambers nicely aligned and in a very good vacuum. There are loads of #vacuumpumps , aluminium foil and #mirrors in the lab https://t.co/I4rzNjEtQA
I like to start my day with a cup of coffee ☕ and checking out recently published papers and preprints @arxiv. It's not always easy to keep track on everything 2D related, so I tend to use @TheOldReader to ensure I don't miss any important publication
After coffee, it's usually lab time 🔬. Setting up a lab can be exhausting as there are a lot of things you need to assemble and align, and sometimes even building. But it's also a lot of fun. It also gives you a chance to practice your drilling and soldering skills 😁 https://t.co/6r1BKkx86B
I'm also working on programming pressure readings, I get to practice my python programming skills @ThePSF Some days I also work from home, mostly when I have some office work and a lot of writing and reading
I'm also trying to keep good work-life balance when possible, so I usually won't work from home on weekends and late in the evening, with the exception of paper/grant/beamtime deadlines, and meeting my colleagues from different time zones 🌍🌎🌏
With this, it's time for me to sign off for tonight. If you have any questions, feel free to sent them and I'll answer them tomorrow :) https://t.co/w8mW4gWkJh
Hello again! 👋 Today I'd like to talk a bit about science communication, both in the academic setting and outside the academia, as well about the outreach.
I think it's very important to share our research with different kinds of public. Unfortunately, in the pandemic year, this is a bit challenging to do in the usual way(s), but luckily there are a lot of online options.
If you have some interesting results you want to share with your academic colleagues, you should definitely check out this recent initiative by the @VirtualSciForum called the Speaker's Corner, facilitating self-invited seminars, https://t.co/UlbPsNz3oE https://t.co/LfFN8MCU6y
@VirtualSciForum is an open, volunteer-run platform for scientific conferences going fully digital. Not only that they organise great conferences, such as Long Range Colloquium, but they can also help you organise a #virtual conference! 😎🙂 You should definitely follow them!
It's been a long day in the lab for me, which is why I wasn't tweeting that often. https://t.co/kQDwctmFWl
But now I'd like to talk a bit about #Outreach and communicating with the not-in-your-particular-field audience #scicomm . How do you feel about outreach and sci comm? I think it's important and usually enjoy doing it.
RT @RobertGaristo: Attention: Authors https://t.co/hjs0vfkH1V
It seems that only people who love outreach and sci comm are on Twitter at this hour 😀
If you want to test your skills in, for example, #scicomm, I really enjoyed Falling Walls https://t.co/vEeCyFrFO3 where you get 3 minutes and 3 slides to present your research I was super excited to win a 3rd place in Falling Walls Lab Aarhus https://t.co/icyItiqR49 https://t.co/CwRAI4f8MN
@FameLab also gives you an opportunity to present your research in 3 minutes, but with no slides and only props you can carry on the stage with you. I participated in Victoria semifinals last year @foundation_wam with 2 of my @FLEETCentre colleagues https://t.co/Gj8cgluOFX
You should check for your local Falling Walls and Fame Lab opportunities, both are a lot of fun and you get to challenge yourself in presenting your research with almost no jargon!
There are also a lot of really great Twitter accounts you can follow, such as @iamscicomm , @realscientists , @IndSciComm , @ravenscimaven , @BlackInSciComm , @samillingworth https://t.co/HBTnRHWi7A
A lot of outreach I did was with @FLEETCentre, led by amazing @Di_Ruka FLEET also has a lot of outreach activities on their pages, including some you can do at home! https://t.co/6Xg3EtvZGM
One of these activities included making simple #Video clips explaining #experimental setup I use. This video was a part of a summer project done by amazin Sean Solari from @Monash_Science https://t.co/T7KzVC8r08
Great initiative is also @SkypeScientist I haven't tried it yet, but it sounds really great and I would love to join! Anyone here did it? How did you like it? https://t.co/3FOjilESwn
Today's topic will be 2D materials, starting with #graphene, and electronic structure. 😎🥳😱 https://t.co/qDupUuj6Uo
Graphene is a single layer of graphite, material commonly found in pencils. Main reason why pencils are so good for writing is that all of these graphene layers inside of #graphite are very weakly bound and separate easily, while leaving trail on the paper ✏️
Graphene is 1 atomic layer thick, and is basically only a surface, so 2D. Really crazy thing, since our world is 3D! All atoms in graphene are carbon atoms, and they are arranged in a honeycomb structure. Something like on this picture https://t.co/uajJIpC78i
#Graphene was first isolated using a sticky tape, a really cool method. You first use sticky tape to peel off a bit of #graphite, and then you use another piece of sticky tape to thin it down. You keep doing this until you get only a single layer of graphite, #graphene https://t.co/5CdLXJ0Vt1
Once you are happy with the #graphene you got, you can either place it on a substrate you want to use, or on another 2D material. Sort of like arranging atomic Legos!! If you are interested in how to make atomic Legos, check out the talk by @semontis #LEGO https://t.co/iRlaiYVN33
#Graphene has many really interesting properties. Despite being just a single layer of atoms thick, it is one of the strongest and most elastic materials we know! It also has a very special electronic properties, such as really fast electrons that have no (effective) mass.
#Graphene discovery was so important that a Nobel prize was given to a A. Geim and K. Novoselov in 2010 for graphene discovery!🥇🎖️ @NobelPrize You can even watch the Nobel lecture on the research that led to graphene discovery https://t.co/K42kB2lREo
#Graphene discovery paper was published in 2004 @ScienceMagazine and you can say that the era of 2D materials started with it https://t.co/JSQKWmnS2h https://t.co/0EPx1BxoVA
[admin] "Supercool Electrons in 2D Materials" Extended podcast with Antonija (@CaboAntonija ) is out now - https://t.co/qd0RUSC1Rn
#Electronic band structure describes the range of energy levels that electrons can occupy or not. States that electrons can occupy are called bands, and ones that they cannot occupy are called gaps. 2 most important bands are called the valence and #conduction band https://t.co/uS2LOVn7l4
These 2 bands are closest to the Fermi level. Fermi level is the highest energy #electron in the material can have. Valence band is under the Fermi level and is occupied, conduction band is above the Fermi level and is not occupied, but is important for the #conduction of current https://t.co/IjjC6CLB29
#Graphene is a special kind of material, it is not just a simple metal or a semiconductor, but is something called a semimetal (or a zero band gap semiconductor), and it has bands in a shape of cones. These cones are called Dirac cones, and are the reason for very fast #electrons https://t.co/s2kVZsfLDF
A really cool video was made by my summer student, Sean Solari @Monash_Science @FLEETCentre , showing #graphene #electronic structure and cones, called Dirac cones https://t.co/wq4caRXYfk Do you have any questions about this (for me) super exciting topic? 😄 https://t.co/Ek5UR868wz
Poll time! There are many different ways to grow #graphene and other 2D materials. Which one would you like to hear about?
@semontis @CaboAntonija I hoped it was early enough for Australia 🌏 but I must have miscalculated! I will make next one open for 12 h :)
Morning! ☕ The winner of yesterday's poll about #graphene growth was molecular selfassembly, so we'll spend some time today talking about it 🎉 https://t.co/Adel8XVg1n
I should have probably called it molecular assembly, instead of "self-assembly", as that is more correct, but anyway, molecules!
Molecular assembly is a type of #chemistry driven bottom-up approach to grow #graphene. Bottom up meaning that we go from small nano-blocks to build a larger thing, graphene. This approach allows for an amazing control over how, for example, graphene edges are defined.
A small molecular blocks, monomers, are combined on the surface and bound into larger units, polymers. Molecular assembly is most often used to grow a very specific kind of graphene, #graphene nanoribbons! Different molecular precursors can be used to grow different nanoribbons. https://t.co/ozFGP3Z0Lx
As molecules are used to grow #graphene (nanoribbons), the edges of the structure are always well defined on the #atomic level, which is really cool! Usual molecular precursors are various molecules that already have carbon atoms arranged in hexagonal rings.
This is a good starting point to grow a larger sheet that is supposed to consist of infinitely repeating carbon hexagons! #graphene 💍 https://t.co/OFTziOqmG5
@Lions_and_Bees So we can have a monomer misnomer? 😁🤔🤔
There are a lot of molecules to choose from, and a very popular monomer to use is 10,10′-dibromo-9,9′-bianthryl. Depending on the type of monomer you use, #graphene nanoribbons can have different edges, width and even doping!
As we mentioned yesterday, #graphene is a semimetal. A semimetal will always conduct electricity and therefore will not be a very good to use in transistors. Graphene nanoribbons on the other hand, can be semiconducting or metallic depending on their edge type!
If you choose a right precursor molecule, and a right substrate, you can grow an armchair-edge #graphene nanoribbon and it will be semiconducting. This is really cool if you want to use them for some kind of transistors, for example. https://t.co/zQmJ3vQzGH @acsnano
#graphene nanoribbons with zig-zag-edges, on the other hand, tend to always be metallic. https://t.co/ncGnmHSCSV
Great thing with the molecular bottom-up approach is the amoutn of control you have when you grow things. You can control the edge type, doping, and with a bit of assistance from your substrate, width and #topology of your #graphene nanoribbon! https://t.co/15ERsbyPxE @nature
You can also make heterojunctions between different #nanoribbons https://t.co/5iG580KMat @NatureNano
All of the previous examples were for #graphene nanoribons grown and measured on #metals. If you would prefer to have them in a different form, you can even disperse them in a solvent! https://t.co/OULLKXZT8w https://t.co/J9Ohphon1b @J_A_C_S
If you would like to learn more about assembling molecules on surfaces, you can follow the work of @DrJenMacLeod @QUT and @DrJayEllDee https://t.co/WsgwiEp0l8 @IOPPublishing
Before concluding the part of molecular assembly I would just like to mention that not only you can grow #graphene (nanoribbons) in this fashion, but you can also use graphene as a pattern to assemble molecules! https://t.co/FVQSv6mEvI @DrJenMacLeod
You can even transfer the self assembled molecules (and atoms) from #graphene to other substrates! https://t.co/Hbdv1AgCn0 @acsnano
This concludes the part on molecular assembly. Stay tuned to her about synchrotrons and my favourite experimental technique, angle-resolved photoemission spectroscopy! 😃😊 https://t.co/kXNY23Nsx9
@DrJenMacLeod Yes, it definitely is! This paper sums things nicely and has some great examples. I guess there are many more examples of self-assembly today. :)
Photoemission and synchrotron time! 💫 https://t.co/GmJzGSRH2b
Angle-resolved photoemission spectroscopy, or as I will call it ARPES, is a technique used to measure electronic band structure of materials. It is based on the photoelectric effect, a discovery for which #Einstein won the Noble prize in 1921! https://t.co/lXIsU5mJZH
Beam of light (blue) falls on the sample and photoexcites electrons (red). Electrons are captured by electrostatic an #Lens and pass through the analyser. Everything is designed in a way to preserve the information about the kinetic energy and angles that electrons have https://t.co/10hWYaHyBq
Electrons that pass through the analyser hit the array of electron multipliers (MCP) that boosts the signal which is then mapped on the phosphorous screen. Finally the photoemission intensity is captured by a CCD camera and you get an image like this (bilayer #graphene). https://t.co/DZ6ItDsNB5
ARPES only measures up to the Fermi level (highest energy state electron can occupy), which is seen as a sharp decrease in the intensity. Also, ARPES has to be done in vacuum. https://t.co/GrGAZUiueK
ARPES can be done with different setups and different sources of light. As a light source you can use a helium lamp, a #laser or a synchrotron! all of these systems have different advantages and disadvantages.
@TobiasAdeJong Hmmm I'm not sure! We recently received our new detector, so once that's up and running, I can tell you if it is the MCP-phosphor-CCD based or the direct CMOS 😀
Poll time! Are there any synchrotron users following this channel or maybe even potential new synchrotron users? 🙂
@Guybrush42 I'm doing something similar to XPS. Principle is the same, but we are scanning across different angles around normal emission to be able to measure band dispersion. Synchrotrons have tuneable energy range and lower photon energy gives better resolution close to the Fermi level
Poll results came in, and it seems that majority would love to get a tour and hear about how to become a user. Luckily for us, many synchrotrons are doing virtual tours #virtualtour ! So after brief introduction to synchrotrons I will be sharing link to some of these tours 💫 https://t.co/WNdG07K1MM
Synchrotrons are circular particle accelerators that accelerate electrons to speeds close to the speed of light and produce synchrotron light that is very intense. Synchrotron light is much more intense than if you produced X-rays with a lab source @lightsources https://t.co/oG9y9DSx4b
Synchrotrons are also able to provide light of different energies (wavelengths), which can affect your energy resolution, but also whether you probe deep into your sample or just the surface. It can produce light in VUV, sorf and hard X-ray range.
Different beamlines, places where light comes out of synchrotron and experiments are performed, will receive light in different energy range. 🌈 Beamline you use (and energy range) will depend on type of experiments and science you are doing.
Hard X-rays are more often used for #biology experiments, while material science and #physics is more often done on the soft X-ray end of the spectrum. Of course, that is not always the case. ARPES experiments, though, are mostly done in the UV and sometimes soft X-ray range
I did my PhD on a small synchrotron in the basement of Aarhus University in Denmark @AarhusUni called ASTRID2, so you could say that ASTRID is my favourite synchrotron! Here is a photo from one of exciting ASTRID beamtimes done with help of a cool dragon, Sissy 🐉 https://t.co/kTs0nbtwOW
I've done a lot of fun and cool experiments on 2D materials on ASTRID, including one where we used hydrogen to turn #graphene from a semimetal to a #semiconductor! https://t.co/wf0Wra6hUP @acsnano
We've also looked into how a 2D semiconductor MoS2 looks when grown on gold. https://t.co/cYY0aD6fMT @PhysRevLett
And here are some really cool ARPES images of Dirac cones!😃 https://t.co/3aYGEXADJK
It's been a busy day in the lab, as you can see, but now I'm back and we are continuing with the synchrotron story! https://t.co/cJCoR4Ut1h
Besides ASTRID, I did some really cool experiments at @MAXIVLaboratory located in Lund, Sweden, and @elettrasincro near Trieste, Italy.
I also had an opportunity to do ARPES experiments at @advlightsource in Berkeley. Great synchrotron with an amazing view. They also have a #virtualtour! https://t.co/zu2cY3FL7o
You can also get a #virtualtour of @DiamondLightSou https://t.co/A6lxBAbIRX
And of Soleil in France #virtualtour @synchroSOLEIL https://t.co/CG6jHSQ2UL
There are also a lot synchrotrons that I didn't have a chance to visit yet, and that also don't have virtual tours, such as @CanLightSource and @AfSynchrotron If you want to see a more detailed list of synchrotrons, @lightsources is a good place to start!
A lot of synchrotrons also do open days where you can get an in-person tour, such as @ausynchrotron , although, that might be a bit tricky during a pandemic 🤔 https://t.co/24ohBdzmgW
And now briefly about how to become a synchrotron user! Most synchrotrons have calls for proposals a few times a year, where you send them a short proposal on experiment that you would like to do. Good start is to check website of the synchrotron and see the format & check dates
Most of beamlines have both technical data, that will make it easier for you to figure out whether your experiment can be done there or not, and also most recent publications. Is there anything from your field there, does it look like suitable for your project? https://t.co/HMpjowpAPv
You can also contact a beamline scientist working on the beamline you would like to apply for. They are very knowledgeable and experienced and can help you decide whether to apply or not.
More practically, when applying, it is always good to have some initial data, to show that the project can actually be done. Also, you should have a plan B and come with several samples (of the same kind). Time is short, and maybe your 1st sample won't work, but 2nd will 🙂🙃
That is all for today! Do you have any questions about ARPES, or synchrotrons and becoming synchrotron users? Let me know! Tomorrow, we will do a bit more of ARPES on 2D materials and also cover some 2D material applications. https://t.co/WQyJWjzUbX
@CanLightSource @AfSynchrotron @lightsources Looking forward to seeing it!
@XtalGrrl Yes, you are correct! As I mostly work very far from hard X-ray regime, I completely forgot about the diffraction experiments 🙂😅
hello everyone! I hope you are all having nice and relaxing Saturday! It's nice and sunny in Stockholm so I'm hoping to go for a walk before sunset☀️🌞 Before all that, I'll tweet a bit about applications of 2D materials, and some more of ARPES pictures https://t.co/8zbBr45Pz3
One of cool applications of #graphene is in corrosion protection. Graphene is very inert and can protect surfaces really well! https://t.co/R9ZknuoSHk
Remember how we used hydrogen to open a band gap in #graphene? Well, you can also use hydrogen to enhance graphene protective coatings! How cool is that? 😎 https://t.co/oH8LcSBJr0 @AarhusUni @advlightsource @ACS_ANM
You might ran into problems if molecules go under your #graphene coating, as they are more likely to interact with the material you are trying to protect than the inert graphene A way around it is to use several graphene layers! https://t.co/yFoWCpRjrQ @LucaCamilli3 @DTUtweet
#Graphene can also be used in flexible, bendable phone touch screens ☎️📱 and in batteries 🔋 There are many companies doing a lot of R&D on graphene applications, such as Samsung @Samsung and LG @LGUS
Other 2D materials also have some really cool applications. For example, single layer MoS2 can be used for transverse detection of #DNA ! https://t.co/DhE8WGi0oq @acsnano @EPFL_en
2D indium tin oxide (ITO) can also be used for flexible touch screens and #electronics This material is also produced in a super cool way, by liquid metal printing! https://t.co/lFhFtJ3TAt @NatureElectron @K_KalantarZadeh @FLEETCentre @semontis @AliZavabeti @RMIT @Monash_Science
There are also ideas to create a completely novel kind of #Electronic devices that will have some additional "bits" (besides 1 and 0) called spin and valley. 2D WS2 is a very promising candidate for this 😃 https://t.co/5zAMXhaG4K @PhysRevLett https://t.co/STlQgK8IjE @PhysRevB
2D materials and their heterostructures are also useful in #catalysis as they have a really large surface area compared to the 3D materials. https://t.co/5McuVIXkbZ @nature https://t.co/n6z2kKW2hH
There are also even more exotic 2D materials that are called #topological insulators, such as Na3Bi, and can be used for futire low-energy electronics https://t.co/ychqFiJhIa @ACS_AMI @FLEETCentre @ShaffiqueAdam @DrGolrokhAkhgar
If you want to know more about Na3Bi in general, as it is a very cool material, you can check this recent review by @surface_matters @FLEETCentre https://t.co/qkPvCAH3VP
Do you know of any really cool applications of 2D materials? Write them in comments! Later today we will do a but more of ARPES electronic structure tweeting! https://t.co/VIZsurqHdB
@smileyATI Hi! ARPES is most definitely suitable for 3D materials as well, I will mention some examples later today. If you are measuring in the UV range it is highly surface sensitive, but with soft X-rays you can also characterise deeper in the bulk. 1/2
@smileyATI Measurements are always done in vacuum, so your sample needs to be able to survive that. Also, surface needs to be very clean. So we are talking either growing sample in the ARPES system, cleaning it by heating to 100+ degrees Celsius or cleaving/using sticky tape to clean it.2/2
@smileyATI Actually, samples can also be grown somewhere else and transported with a #vacuum suitcase. You just need a surface that's clean of adsorbates. Measurements are typically room temperature or at cryogenic temperature (to improve resolution). You can also heat samples a bit.
A bit more ARPES and 2D (and bulk) materials before we finish for today!
Even though I'm mostly working on 2D #materials , they are not the only type of materials ARPES can measure! "Regular" 3D crystals, and even quasicrystals and heterostructures can be measured with ARPES.
One popular group of materials that are studied with ARPES are topological insulators such as Bi2Se3. They also have linear dispersion similar to graphene, but their Dirac cones are 3D. https://t.co/tnmQEICbDM @ScienceMagazine
You can also use ARPES to studi 2D electron (or hole!) gas on the surface https://t.co/dXe1j8TKiT @PhysRevB @DiamondLightSou @AarhusUni
Or even a combination of the two, topological states and 2D electron gas states! https://t.co/y8Nia8CosF @NatureComms
Closely related to topological insulators are topological crystalline insulators (different underlying symmetries and level of topological protection), which can also be studied by ARPES https://t.co/5wRPFJ6Ah6 @acsnano @MAXIVLaboratory
Sometimes materials are 3D, but they are layered and the layers don't interact strongly with one another, at least not strong enough to matter for the electronic structure. To determine whether the electronic structure is 2D or 3D, you do ARPES at many photon energies https://t.co/mXzw50YlnK
There are many materials you can measure, including "regular" metals, such as gold https://t.co/JPf5NSBM9g @PhysRevB
You can even measure diamonds, although with some difficulty! https://t.co/6RVi4vWuoV @PhysRevB
You can measure ferroelectrics, such as In2Se3 https://t.co/Y5jGAvxsRO @FLEETCentre @advlightsource @ausynchrotron @Nikhil_Medhekar
You can also measure heterostructures, such as very popular twisted bilayer #graphene https://t.co/SLxJS4GM3X @advlightsource @nature
ARPES measurements can also be combined with other techniques, such as LEEM (and very often STM) https://t.co/orCfLbh25l @NaturePhysics @elettrasincro @TobiasAdeJong @j_jobst @sensemolen
And you can even do ARPES on your gated devices! https://t.co/0Sr5L8yKX2 @AarhusUni @DiamondLightSou
You can also measure "regular" heterostructures that don't have magic angles https://t.co/y75GiKifJ8 @acsnano @CLF_STFC
And you can even probe correlated phases! https://t.co/5fhq1Hqesx @IOPPublishing https://t.co/fUK5tigPJd @Kinggroup_ARPES
And before I forget, you can also measure ordered molecules on surfaces! https://t.co/U4Vzi3wlmE @NatureComms And quasicrystals! https://t.co/ox6xctPRVI @synchroSOLEIL
@smileyATI No problem! If you have any more questions, feel free to ask them. I will be curating until tomorrow evening.
This has been A LOT of ARPES stuff and quite a few papers, but it doesn't really cover everything . What are the materials you are interested in? If you want to know if ARPES can be done on something you work on, write me a comment! https://t.co/P0RAPsxvzW
@Abate_Parini Ahh yes! I should have mentioned the importance of a right colour palette in ARPES and how long it takes to choose one that's best for both Fermi surface maps and band dispersion images 😅
@Abate_Parini @MAXIVLaboratory @elettrasincro Elettra is really nice, a lot of good beamlines, and probably has the best coffee (and pizza and ice cream) you can get on a synchrotron 🤔 SGM3 on Astrid also does an amazing espresso, but no ice cream 😊
@Abate_Parini @micheledalai @RaiRadio2 I believe I really need to hear this story, it sounds amazing 😁
Hello everyone! ☕ Today is my last day curating and I just wanted to say that I really enjoyed it and had a lot of fun. If you are working in #nano, consider applying to become a curator for a week!
As the last topic, I'd like to briefly discuss collaborations and open access publishing, as those are some of the things I think are important in science today.
There is a lot of push to move to more open access publishing, for example Plan S in Europe, in order to make science more accessibly. This is something I think is really important, as it will make science more accessible to our colleagues and general public.
Unfortunately, it often costs a lot of money to get your paper published open access. Luckily there are some alternatives that can still make research more accessible. One of these alternatives is a use of preprint servers and self archiving.
In #physics it is quite common to place preprints on @arxiv and majority of journals allow for this, which I think it is great! Of course, these are not peer-reviewed articles, but it still increases accessibility and you get access to new research much faster! https://t.co/RDMVis3Wm6
Are preprint servers common in your field and what are they?🧐🤔❓❔
Second thing I would like to talk about today are collaborations. 😃 Majority of work I do is highly collaborative, and if you look at my publication list, you will see that most of my articles have very long list of authors. https://t.co/7bHzBAzJy4
In part, this is because I am doing a lot of work on synchrotrons and ARPES experiments usually require a lot of input from beamline scientists. We also often get new materials from our #chemistry and material science colleagues and get support from #theory group for models.
All of this means that there are a lot of people involved. Of course, there are also projects where you can do everything "in-house", prepare a sample, do measurements and make simple model. 😄
I enjoy collaborative projects, as you get to learn a lot. One of my favourite projects was done in a collaboration with an electrochemistry group during my PhD @iNANO_AarhusUni. I was preparing #graphene on iridium which my #chemistry colleagues would then transfer on silicon.
I got to learn a lot from them and the project was a lot of fun! We successfully transferred #graphene from iridium https://t.co/LC3YGHvUvq @IOPPublishing and I also got a publication in a #chemistry journal https://t.co/CLOvDLsvom @ChemEurope 😎
@carlosromvil @arxiv No, unfortunately those are usually not allowed so preprints don't fully replace an open access publications. Different journals have different rules, though, so it is a good idea to check them when posting preprints. Sometimes they allow for different versions to be uploaded.
Doing ARPES also means that I frequently publish in collaboration with beamline scientists. Those projects are always exciting because often it means that you are doing something very new on the beamline. https://t.co/Xld1vO8dkT
Sometimes this means that you get to be one of the first people to use a new experimental setup. For example, I got to be one of the first users on a newly commissioned ARPES endstation @ausynchrotron last year https://t.co/y2FT5pwUyV @arxiv That was a lot of fun!
I often also collaborate with theory colleagues. Even though we can use ARPES to directly measure #electronic #structure , often you need to have some theory to compare your data with, or to clarify things. It is always fascinating to see how they go from code to physics 🤯💻🖥️
What about you? Do you collaborate often or is it more an individual endeavor? And if you collaborate, is it interdisciplinary or more within your field? https://t.co/gJdcTMV9Oz
That's all from me! If you have any questions and/or comments, I am curating until this evening. 🌆 If you come up with some questions later, or would just like to see more cool ARPES research being tweeted often, you can follow me at @CaboAntonija 😀 https://t.co/HkxIuOE4DU
@Abate_Parini Definitely 😁
[admin] Thank you @CaboAntonija for a wonderful week fo science! Catch her podcasts here - https://t.co/MwNMlxLJpB https://t.co/7vnvZ3jR61
Peter Sherrell
[admin] "Nanoavengers Assemble!" Please welcome Peter (@NanoIn3D) and listen to the podcast to know what is coming your way this week https://t.co/yyiZw4MYC4
RT @O_Ganics: 🙌🏾🙌🏾👇🏾👇🏾 learn more about what I do 🤗
RT @EmmRankinWilson: If you work in or are just interested in all things #Nano give @RealSci_Nano a follow and check out their podcast seri…
Hi Everyone! I'm Peter (@NanoIn3D), a Materials Science and Nanotechnology researcher from Australia. Exciting to talk to you all this week about me, research that interests me, and science in general! Read below and I'll break down what to expect from this week 👇 https://t.co/WFdmiO98BS
I'm going to try to break up 'hard' science with other aspects of scientific life this week, so I'll talk to you about: 1. My journey so far - how did I get into science, where has it taken me, and what's next? ❔🏖️✈️🌨️🛬🌆🛬☔️
2. Nanomaterials! How can we make them, why do we care? ♨️🚙🏭🏗️🧬💉💝⚡️ https://t.co/0Ail9ktQEv
3. The art of science (definitely the 'art' side of things here) - with a strong disclaimer I have no artistic training or taste at all! 😀 🎨🔬🖼️🌈 https://t.co/386BJlknmr
4. Nano-(avengers)-materials assemble What happens if you stick all these materials we make together? How can we do it - what happens next? ⚡️⚡️⚡️⚡️⚡️⚡️⚡️⚡️ https://t.co/P39BkSoJHA
5. Wearable energy harvesters - one of the big things I'm working on at the moment. Turn that run, skip, walk, or even typing into electrical energy you can use! - all through nanomaterials and nanomaterial assembly. https://t.co/nVWFwYY39O
That'll take up a fair bit of time - I'm keen to engage with questions, see what everyone is interested in. I've put up a poll below of some extra topics and I'll try to get to the most popular things on it over the coming weekend!
So to start with today I’d like to dive into why and I got into my journey ( at least so far) in Science! 🥼 I have always loved learning, figuring out something new, and breaking things apart and trying to put them back together. https://t.co/wtK2LJbheB
I’ll preface this by saying I am privileged to be here I wouldn’t have made it this far without brilliant family support and the low-fee Australian university system. https://t.co/QuutMDUGFp
Emerging from High School #Nanotechnology was brand new – and @UOW was offering a degree in this unique field of science. Wollongong was home – and one of the most beautiful places in the world – so that’s where my journey started. ☀️⛱️🧪 https://t.co/oGRYMG2Drm
The degree was effectively a double-degree of #Chemistry ⚗️ and #Materials Science & Engineering 🪡🚂– with a smattering of physics, biology, chemical engineering thrown in. (phew that’s a lot)
One thing the degree did exceptionally was expose undergraduates to active researchers from a very early point – I was getting experience in IPRI (now @ARC_ACES) labs from 1st year! This lit a fire for me in a career I previously knew next to nothing about. 🔥❔❓
Before I knew it - I was doing a Ph.D. in #CarbonNanotubes for #Supercapacitors and #FuelCells – and loving (nearly) every minute of it! I'll talk a bit more about the science of this tomorrow https://t.co/3HaNhRODOU
I’m going to pause the story there. I’ll take up with the end of my Ph.D. and post-doc experiences a bit later. ⏯️
I never get even this far without amazing opportunities 1.Access to low-fee education ☑️ 2.Exposure to world class researchers☑️ https://t.co/8otUglr6yT.D. stipends☑️ https://t.co/252TnEgtQX support☑️
A lot of these are politically charged now – but they remain crucial to scientific 👩🔬, technological 🚂, and societal development👨👨👧👧. You can’t switch research off 🛑and on 💡again – it takes time ⏳. The bit so far has been ok – the challenges will come next! https://t.co/Ajpn1Iv9b7
So I was doing a Ph.D. on #CarbonNanotubes What did that mean? ☑️ What came next? ❓ https://t.co/e4HhNDcdKh
#CarbonNanotubes (CNTs) are super cool materials – they’re basically a sheet of graphite (graphene) ✏️rolled up tightly into a tube. In the same way as rolling a sheet of paper makes it harder to bend, rolling up graphite makes it much stronger too 💪💪. https://t.co/CRELWloCsa
Unlike rolling a piece of paper, which is still a piece of paper that isn’t conductive🤦 CNTs are much more conductive that graphene – up to ‘ballistic conductance’ ⏩⏩which sounds super cool but just means conductivity is independent of length (ok – that’s still super cool). https://t.co/tqs8gr71IQ
This happens because the electron orbitals on each atom are deformed by the CNT being rolled up – so they overlap a bit more. This concept is pretty simple, but really defines what I try to do in my research – control the form of a material to manipulate its function! 🗞️⚡️☑️ https://t.co/3JoVG0UF4P
As CNTs are strong and electrically conductive (and chemically stable) – as well as made from one of the most abundant and well understood elements on earth (carbon) 💎 – they are great for energy storage 🔋devices! #Supercapacitors #FuelCells More on this tomorrow!
I ended up completing my Ph.D. in August of 2012 – after starting in 2008, so 4.5 years doesn’t seem too long. https://t.co/9yBOeGzQEE
The Australian Ph.D. award system is slightly different, in part due to isolation. 🏝️ The thesis is sent away for review with no fixed date it’s coming back – most come back in 3 months. 📔 Mine took over 12 – simply because the reviewer was sick. 🤦
This was a bit of a boon and a curse A boon: it extender the start of my ‘ECR’ period – the time given to you to establish yourself (or not) as a researcher ☑️ A curse: it was a massive detriment to my mental health.🙊
This time also let me explore collaborations visiting @UCLA and learning all about 2D materials – which is what I focus on nowadays - and led to some of the work I was most proud of 😃 – figuring out how to control nerve cell growth with graphene.
There isn’t a resolution, or ‘point’ to me mentioning this – just that everyone goes through struggles and destigmatizing it is important. Some things are just out of your control.
Still there were lots of positives During my Ph.D. I met my wife (@DrTinyTaps) – you should check out her research into tissue engineering, it’s super cool! 🆒 However, find a post-doc for 1 person can be challenging, finding 2 at once in the same city – extremely difficult! https://t.co/4rxXOg5gzd
We ended up moving to Sweden 🇸🇪 at the start of European winter – and after 3 months I started at @liu_universitet 🧳🧳🛫✈️🛬 Using Carbon Nanotubes additives in collagen and alginate hydrogels to develop new ways to repair the scar tissue on the heart after a heart attack. 🫀
Sweden was a wonderful experience, culturally, personally, and scientifically. ☑️☑️ I learned a lot about different ways to do (and not to do) science – I can’t recommend travelling and gaining different perspectives enough.
There are challenges in learning a new language, trying to embed yourself in a new culture – and surviving -20C temperatures (as an Australian – this was probably the biggest shock!) The positives far outweighed the negatives though. https://t.co/JNb13LViXb
However, after 2 years in Sweden it was time for a change. To this end it was time to travel again 🧳🛫🛬🧳, and after writing a Marie Curie Fellowship application it was off to London to join @ImpMaterials 🇬🇧
I’ll leave this thread here – I’ll finish off my story (so far) about London and Melbourne in a coming thread. https://t.co/JIqq2xtMqe
One thing that stands out - was that I didn’t really understand the importance of those first few years. ⁉️ Looking back, being more selective about where and what I worked on would have strengthened the future years. Lots of benefits ☑️– lots of mistakes too 🤦!
So I moved to London 🇬🇧 for a prestigious fellowship 🍷 What was the plan? 📰 How did it go? 🚨 https://t.co/O5RyJ5hls1
I was moving to get back to energy materials research - looking at growing #graphene - that single layer of pencil graphite - in 3D shapes. https://t.co/OEiFyfoKOK
This is important as #graphene is an amazing material ☑️Super strong ☑️Electrically conductive ☑️Chemically stable ☑️Light weight But to build something practical out of it, we need to assemble many #graphene layers together again, without it becoming #graphite ❌!
We used a super cool #ChemicalVapourDeposition furnace and some #3Dprinted metal scaffolds to start this, and got some amazing preliminary results. 🥼 (I'll go into science CVD more in the next thread) https://t.co/Kiy4s1E5Oj
Unfortunately, that super cool furnace broke - and because of how specialized the system we were using was - this mean the work got put on hold 🤯🤯 This was amazingly frustrating as the project was my baby at the time. It's still not done - hoping to revisit it soon!!
We did write a review article on 3D graphene structures - if you're interested in reading deeper into what we were trying to do and why - have a read: https://t.co/ApQM0AudZk
During this time I was working in the @MatteviC research group, Dr Mattevi is an expert in 2D materials - especially #TransitionMetalDichalcogenides. So I pivoted my research focus into these 2D materials - which are amazingly versatile
Unlike Graphene which is: ☑️1 element ☑️1 atomic layer thick ☑️flexible ☑️1 material Transition Metal Dichalcogenides are: ✔️2 elements (a metal, and a chalcogen) ✔️3 atomic layers (one metal layer between 2 chalcogen layers) ✔️rigid (ish) ✔️a family of materials
The fact it's a family of materials is super powerful, you suddenly have a huge range of chemistries 🧪 you can play with (beyond carbon) - electronic properties. The beauty here is you can stack different TMD chemistries together almost as though they were one material! https://t.co/mxouVtOt9G
Again I'll go into the science later - but this is another example of how research moves in unexpected directions. Things aren't controllable. I learned a ton of new things in London - and experiencing such a wonderful environment @ImpMaterials set me up for my future.
Being based in Europe also let me travel and experience different cultures to an extent so difficult when you're in Australia! Loved (nearly) every minute of it - I can't emphasize the advantages of this from a research and life perspective enough.
After 5 years in Europe 🇪🇺 it was time to come back home to Australia 🛬- we had a new born baby - and my wife (@DrTinyTaps) was awarded a prestigious VC Research Fellowship (Lecturer) at @RMIT. https://t.co/9HlDGjj6DV
We made the decision that I would take time off work to raise our son. This time was amazingly challenging, moving countries 🇦🇺🇬🇧, finding a house 🏠, being without steady income ❌💰, having a child under 1👶.
Career disruption due to children is a real problem. This burden is disproportionally held by women 👩🔬 - there is an emerging recognition of this ✔️ - a lot more needs to be done to support reintegration of carers into the academic workforce. A huge amount of talent is lost. https://t.co/PtNhjSi8RO
I was lucky enough to be able to return to work in The Ellis Group @engunimelb after 9 months at home. They were (are) amazingly supporting - I had flexibility, working 9 day fortnights, and a lot of understanding about my limitations. It was still hard to juggle everything🤹♂️ https://t.co/WgDjCEyNgG
There is also a lack of recognition in things like grant proposals for career interruptions of of male carers who take time off for child rearing. Again - this is just something written to raise awareness of - not a complaint.
I'm loving working where I am now @engunimelb - doing some amazingly exciting science on energy storage and conversion devices made by assembling nanomaterials ✔️Piezoelectric Polymers 🩹 ✔️Supercapacitors⚡️ ✔️Batteries🔋 ✔️Sustainable Building Materials 🧱 ✔️Catalysis 💥
I look forward to sharing my science 🧑🔬🧪👋 with you over this week! Have questions ❓❓ about my journey - want to know the challenges/successes I've skimmed over here? - Ask me in the comments!
@MySci_PK Beautiful places! The travel of academic life (ignoring 2020) - is a huge bonus. Cultures - experiences - language - you learn so much beyond science by working in a different country. Always value the people you meet too! https://t.co/mgjywg9Gay
This week I'll talk about 1. My journey - done! ✔️ 2. Making Nanomaterials! - Coming right up! 👇👇 3. The art of science - 🗓️ 4. Assembling Nanomaterials - 🗓️ 5. Wearable Energy Harvesters - 🗓️
So lets get starting making nanomaterials! First – there are two main approaches: 1.Bottom up – starting from building blocks and making nanosized materials 📈 https://t.co/ECPZO1jb1a down – starting from a larger material and etching/milling it to make nanosized features 📉
Pretty much everything I do is bottom up – so I’ll be talking about the ways we do this today! https://t.co/Dn3paG51mX
Nanomaterials are tricky to make – you need to give them energy to grow 📈– but stop the process before they get too big! This means most processes use heat and/or pressure 🥵to provide energy to start the reaction – and cooling/quenching 🥶to stop it Lets get into it!
We can do nanomaterials synthesis from gases, liquids or even solid starting material. Gases ⛽️ (not that gas!) are my favourite – so I’ll start talking about my long acquaintance, Chemical Vapour deposition or CVD 🔥🔥. https://t.co/Wz0MdG0dU6
CVD is a quite simple process to talk about – everything is in the name – you take some ‘chemical vapours’ (gases) and ‘deposit’ them on a substrate to form a new material. https://t.co/pgyZ02nNeH
In practice CVD is most commonly done with a tube furnace – effectively a long tube of quartz or alumina that runs through one or multiple furnaces. We hook this up to a vacuum pump so we can lower the pressure as needed. 👇 Thanks @stephen_beirne for the schematic! https://t.co/ZVvnFPW93R
High temperatures ♨️ means we can vapourise our precursors and provide energy for them to react Low pressures 🌩️ makes it easier for our starting material to get into the gas phase or stay in the gas phase.
Choosing the substrate for the gases to ‘deposit’ on is crucial as the crystal structure 💎💠♦️(or lack thereof) 🪟 of the substrate affects how the nanomaterial assembles!
Lets talk about simple systems – carbons. Specifically carbon nanotubes. To grow carbon nanotubes we only need a single furnace, some hydrocarbon gas – typically methane, ethane, ethylene, or acetylene – and a metallic catalyst for the gases to deposit on. https://t.co/8P8wu2BBjl
We heat the gas up to around 1000C 🔥 which causes it to break down into its atomic carbon and hydrogen components 💥🌬️. At the same time, the metallic 🪙 catalyst is changed by the high temperature as well.
When carbon radicals at this high temperature interact with certain metals (Iron, Cobalt, or Nickel most notably) they dissolve in it (like in iron to make steel). You can picture this as a sponge absorbing water - although the carbon is chemically bound to the metal!🧽🌊
These metal particles can only take so much carbon at once though, what happens when they’re full of carbon but we keep supplying hot gas? ⁉️🔎👇
Well what happens is carbon keeps going into the metal particle, but because it’s full it pushes new solid carbon out of the other side, potentially forming carbon nanotubes! This is called the Vapour-Liquid-Solid mechanism (VLS) 👇 https://t.co/J1OgjjrqtL
Depending on how fast you push carbon in (temperature/pressure/concentration), and what type of metal used, we can tune the length, diameter, and wall number of CNTs. This method is great for making large areas of nanotubes in defined geometries! You can even line them up! https://t.co/f4dKDAQWHN
One of the things I like about science is your ability to take something simple, and change it and make something new. Carbon nanotubes are just hexagons all next to each other. 6⃣ What happens if you put a pentagon 5⃣ or heptagon 7⃣ in a CNT ⁉️
Answer: They twist! https://t.co/teA2N8ldXY
The advantage of making twisted carbon nanotube is they open-up a lot of space between adjacent carbon nanotubes – meaning we can fill this space with interesting things like electrolytes for batteries 🔋or chemical functionality of sensors📤! All that space 👇 https://t.co/zfcDMpLGBc
We did this in our research by adding Sulfur to our CVD system, giving us exceptionally conductive, porous structures! We also cheated a bit by using acetylene to bind individual CNTs into a single film – because it reacts with itself! https://t.co/7S8Fa6Ufqy
If you’re interested in this type of thing: We could use these devices for: Sensing: https://t.co/9szbTDUor7 Capacitors: https://t.co/dlFW6WDX2U Batteries: https://t.co/teVM1b8VyW Fuel Cells: https://t.co/2LQMaqV9d1 📰📰📰
I'll move onto graphene, and transition metal dichalcogenides synthesis via CVD in a new thread a little later today! https://t.co/99WxmYU0sg
Lets move away from Nanotubes 🗞️🗞️ now - into the wonderful world of 2D materials, Graphene and Transition Metal Dichalcogenides! 📜📃📄 https://t.co/dwhOhSoCDa
Lets start with graphene – it’s the same chemistry as CNTs – but a different growth process 💥🌬️⁉️ First of all, rather than use metallic catalysts and metal particles – we use metal sheets (normally Nickel or Copper).
Why the difference? – and I’ll focus on copper here because the nickel mechanism is a bit harder to explain. Well, graphene grows by templating on the crystal lattice of the metal and the copper surface – normally (111) – is ideal for this. https://t.co/r6KxhQrxcD
Secondly, because the ‘solubility’ of carbon in copper is so low the reactive carbon species from our gas phase doesn’t dissolve in and then precipitate out of copper during cooling breaking the up the newly formed carbon layer! (from: https://t.co/EXozD0exzJ) https://t.co/ThQpvUMjev
Since this method is effectively chemical self-assembly 🧪you can start to do 3D structures 👇📰– provided your starting architecture is smooth and pure enough! Getting graphene off 3D foams in one piece is a whole other problem - but that's not for today! 🤦♀️🤦♂️🤦 https://t.co/Z1x81Pohfz
Transition metal dichalcogenide CVD growth is a bit more complicated! ⁉️ They template on a substrate just like graphene ✅ – but now you need to have a chemical reaction between two different elements as well🧞🧙♀️! Don't worry - it's not magic - still chemistry!
Due to this difference you start to use a lot more gases! Rather than just a hydrocarbon and hydrogen as active gases, for TMDs you either use solid precursors, or inorganic vapours containing each element itself! https://t.co/o4pd8sPA7W
My work has focused on using solid precursors for synthesis – so I’ll focus on that here. Because we are using different starting materials we now need different temperature at different points in the furnace 🔥 to get each one in the gas phase 💨 at the right time ⏲️!
To give you an idea of the spread of temperatures – for one of the most common TMDS – tungsten sulphide (WS2) – we used 150C for sulfur and 850C for tungsten! This is a huge temperature gradient 🏔️.
Also because the ‘weight’ of the element being carried in the gas phase is a lot heavier – these will deposit on a substrate at different positions along the tube furnace. Finding the right place where the right amount of S and W deposit is crucial! See below 👇 https://t.co/iuRRZkcTC2
If you do it right though, you can get beautiful triangles. https://t.co/JvCkSXWtWl
Or beautiful films (the blue is MoS2, the purple is the silicon substrate!) https://t.co/NCsDrza2Oj
And if you change how the TMDs bind to the surface, you can even make the 3D structures I’m so fond of! https://t.co/fmzIikVZHF
TMDs are great for catalysis! Have a look how we used these systems to break down salt water here: https://t.co/TUeOjJh1pC And how we describe the fundamental growth processes here: https://t.co/jfcVYaT40E
I’ve tried to keep this pretty simple – please comment below if you have any questions or want any concepts expanded on!
I'll be back a bit later to talk about our solution phase synthesis of metal nanoparticles and some more TMDs! https://t.co/jmr7WhTM5x
@MySci_PK Lets see if I can dig them up - these ones are pretty old! https://t.co/m3rV76mlM0
Moving on from gas 💨 phase synthesis - lets have a talk about how to make some selected nanomaterials in solution 🥤! I'll talk about: 1. Transition metal dichalcogenides 📜📜; and 2. Metal nanoparticles 🪙 https://t.co/PzfqMQHLwk
Lets start with TMDs! Growing TMDs in solution is quite tricky - you need to: A) find two starting materials of the metal, and the chalcogen that can dissolve in the same solvent; ✅and B) Make them come together in the right way to grow a 2D material ✖️
Luckily there are a lot of different precursors out there. But making them come together in the right way is not so simple! https://t.co/YxAvwcsxlK
There are a lot of different variables that you can try in solution phase synthesis: 1. Temperature ♨️ 2. Pressure 🌩️ 3. Solvent 🥤 4. Precursor ⁉️ 5. Concentration 📈 6. Rate of precursor addition 💉 7. Time ⏲️ 8. Additives 💊 and many more https://t.co/kvtM9a9yxh
For 2D materials - (like TMDs) - the key things to control that give you an advantage are the solvent and the additives. It is crucial to select an additive (or ligand) that binds strongly to one 'face' of your material - this can stop your crystal growing in that direction!
The problem then becomes controlling nucleation - growing pure 2D sheets is hard - all start from the same point and grow outwards into beautiful flowers! 🌻🌹💮 Below is some of our work growing WSe2 and Bi2Te3 (ok tha'ts not a TMD but still 2D!) Scale bar = 5 nm @MySci_PK https://t.co/aK8GkcB7pH
If you're interested in reading on these type of things in more detail - including a great review on how to make TMDs in any way - check out these 👀👀: WSe2: https://t.co/ynt1AK8H9L Bi2Te3: https://t.co/N744tZXPJy Review: https://t.co/wgsueaIwyX
Now we've got the complexity of growing 2D materials in solution out of the way - lets talk about how to do metal nanoparticles. These are a lot simpler to control because you don't have worry about restricting their growth in any direction! 😅
Instead, the key challenge in growing metal nanoparticles 🔹is to stop them growing into being - well - just particles 🔷!
Similar to the selective ligands we used for 2D materials, for metal nanoparticles a 'capping agent' to stop them continually growing or 'agglomerating' is normally used. The most common of these is sodium citrate - something that comes from citric acid!
There are a multitude of chemistries that you can use to make metal nanoparticles. I'm going to talk about my favourite way because it's: 1. Quick ⏲️ 2. Easy ✅ 3. Cheap 🪙
If you take a metal salt, something like Gold Chloride, and put it in Ethylene Glycol - heat it up and stir it overnight you'll notice you get a beautiful colour change 👇👇 - it's basic - but if you add NaOH it'll go even faster. https://t.co/f80UbWt5A8
This still takes a few hours - and if you're particularly impatient (like me) you'll want to harvest your gold dust even quicker. We're already heating ♨️, we're already adjusting pH 🧪 - so how do we speed it up even further?
Well, you really just need to find a way to provide more energy ⚡️ to your reaction! The easiest way in this case was to place it in an old microwave! (yes the type you reheat food in) 🧑🍳
If you put the same solution in a microwave and turn it on for just 120s you get beautiful reduction (to give you an idea below here is the 'absorption spectra' of both normal, and microwave reduction) https://t.co/dvd7t4MjWd
I'm talking about gold here, but the same thing holds true for platinum, palladium, nickel, silver, copper, and cobalt nanoparticles - just with different starting precursors.
120s is great, 2 minutes. But can we make this even faster?? The answer is yes✅! If you add a tiny amount of carbon nanotubes - you take this time from 120s to 10s for reduction⌛️. Why? - what's going on here? https://t.co/BjuJukYdyG
Well, the structure of CNTs has lots of C=C double bonds - and one thing C=C double bonds are good at is absorbing microwave energy. This means at the wall of the CNTs two things are happening: 1. Localised heating; and 2. They become highly reactive (forming a carbon radical) https://t.co/xWwuzGiNIF
This carbon radical is highly highly reactive - and will donate it's electron to 'reduce' the metal salt in solution to a metal nanoparticle. The CNTs become a little less conductive - but we can live with that! Proposed mechanism below 👇 (from: https://t.co/dlFW6WDX2U) https://t.co/ZbJHLyPZaW
So what does this look like? Beautiful assemblies of CNTs and metal nanoparticles - just the start of our assembling of the nano(avenger) materials! All in just 10s! https://t.co/j0LUjttQPS
Again - I've tried to talk about concepts rather than specific details, but any questions leave a comment below! 👇 I'll be back later to talk a bit about the art of science! https://t.co/WjrRFiSt1e
@Lolchu These are called 5,7-ring defects. The bonding of the sidewall of CNTs is really a delocalised sp2 network. When you interrupt the aromaticity of an area (i.e. a 5,7-ring defect) you are change one (or more) carbons in those rings to sp3 - and cause the CNT to bend or twist 👇 https://t.co/3zFWZ1fris
@Lolchu Something I didn't detail too much in the thread above is there is a lot of H during CNT synthesis from: 1. H2 gas 2. decomposition of hydrocarbons In our case, either H or S - can react with these defect sites to form either sulphate functionality or hydrogen termination.
@Lolchu The modelling CNT growth is in nanoseconds! It's a hot system (around 1000C) so it's really unclear exactly what the bonding state is during the actual reaction. Or at least it's beyond my understanding. We characterise the produced materials and infer understanding from that
@thushrocks It is related to the size of the particle - but not wholly dependent on it. Due to the temperature of the reaction the metal itself can get deformed quite dramatically 👇 The image shows a Ni particle in a CNT - this happens when you have weak substrate-metal interactions https://t.co/EuD8bUp6dk
@thushrocks Have a look at 'fluidized bed' CVD , where particle size is even more loosely defined. You can even grown aligned CNTs on metal foils - where there is no clearly defined particle at all. It's all about carbon solubility and catalyst-substrate interactions!
[admin] "Nanoavengers Assemble!" Extended conversation with the amazing @Nanoin3D is out now https://t.co/l9I8Vb0eeF
Science communication is a hugely important art form 🌍 It helps your audience understand the implications of science, It can drive change, It can boost your personal profile. (preaching to the choir here I know) 🎶
I'm not a great science communicator, but my science (assembling different nanomaterials) creates brilliant features that can be exploited to create beautiful visual effects 🗻. So the path I use to create art from my science (and hence broaden engagement) - is visual 🖼️ https://t.co/52bxasz8Rv
Before pushing something out there as 'science art' - the question often becomes: what are you trying to achieve ❓ what information are you trying to convey ❔ why are you sharing it ❓
In many cases - my 'science art' starts from 'hey, I have a cool microscopy image' - lets see what we can do with some colour 🎨 These like those below - make visually interesting pictures - but don't really highlight any of the science 👇 https://t.co/LYa1V1Zfks
The carbon nanotubes are beautiful - but there is no information conveyed by the use of colour here at all. In fact there is more information shown just by using the raw data 👇 (yellow is platinum particles on a CNT) https://t.co/7JI7D7WiVz
However, my photoshop skills are pretty limited - so combining elemental maps with clear visuals (at least on the nm scale with CNTs) - is a bit beyond what I can do! 🤦 One thing I can do is try to emphasise the 3D structure that I'm making Whether CNTs 👇 (use 3D glasses 👓) https://t.co/1p94FzyhaG
Depth fading 👇 https://t.co/YE0zHy84vB
or just stitching multiple images together to give a sense of perspective to what you're looking at👀. (This one needs expanding to see properly) https://t.co/NKC8Jya8tM
Despite all of these showing the 3D structure really well - no-one can really interpret *what* they're showing or looking at 🤦. So how do we go about trying to improve this? https://t.co/aCBOxni1F6
Well, the best way I've found is going to back to writing rather than art. Add a poetic (or not) sentence that can draw the audiences attention to what you want them to take away from your picture. Draw a parallel to something familiar or historical. Tell a story.
These fractal nanocrystals let us make fuel from water, giving lots of space for water to move in and out and react! https://t.co/nNCrZ8oyDD
These nanosized platinum whiskers hug a carbon mat, providing power to technology that can produce energy for cars, buses, and trucks! https://t.co/k1rxwmYauq
This microscale salt (NaCl) crystal - the same as you'd find on your table - has little nanowires of a 2D material (WS2) growing from it - hinting at how salt can influence the way these amazing new class of materials grow. https://t.co/AzXjVawXod
You'll notice these don't have scale bars (😉@MySci_PK) - it's an intentional choice - the aim of these is to capture attention 📸. I give a general scale in a caption that accompanies it - but because they are all manipulated images - I don't try to pass them off as exact! 🥸
The final thing I'll add here is - try to be inclusive in your art - there are a lot of people with colour blindness - (try to) pick colours that contrast and are visible to everyone. At least there are a lot of tools in image editing software to check this now! https://t.co/dvubsgES6J
I hope you've found this at least visually interesting - leave a comment 👇, ask a question ❓if there's anything you're curious about!
@IreneSuaMar @MySci_PK They sort-of are a bit like that - if you peel the film off the substrate it curls off and bounces on a macroscale➰! (sorry for photo quality!) Who knew all that open porosity on top and a dense base layer would lead to internal stress during cooling 🧊 https://t.co/tU30fk5IT6
I did forget to mention it's much easier to do with cross-sections of 2D materials! (green is MoS2, purple is WS2 - lines are the individual layers from HRTEM) https://t.co/GmO2vgkjSc https://t.co/QO7flilVZC
On the topic of science art vs. scientific images as an information tool - this is really timely post considering my last thread 😅 https://t.co/HZixeKMGl5
@bansealgair Necessary: S - Communicating without jargon, we're so trained to talk and write in a certain way, stepping back is hard T- Liquid Nitrogen, lets you break the materials in half to see what's inside! Useful: S - Accepting your prediction was wrong T - heat proof gloves!
@haleyykinnzz There might be other things in there - but NaCl certainly makes up most of table salt: https://t.co/7iWox9IRve
@barrygoldman1 These actually came from a failed experiment - their a mix of copper, tungsten and sulfur. We were looking at trying to grow WS2 via chemical vapour deposition on 3D substrates - and of course - we just made W-doped copper sulfide!
@MySci_PK This one was Tungsten Disulfide - interesting thing about this sample was the open pore structure on top actually changed the colour of the film - these were a deep teal/green colour 🟩. A nice change when everything you're used to working with was black ⚫️😅
@barrygoldman1 We didn't have a look at it too specifically for these samples but in general: 1. They grow like this (sort of like fractals) because you start from a (very hot) solid metal foam and are flowing hot gases over it. The metal absorbs/reacts with the elements in the gas and expands
@barrygoldman1 because the sample is expanding and absorbing new elements it tries to expand in directions where there is more space to move (hence a spiral/fractal sort of pattern). 2. The rounded edges come from the symmetry of the crystal structures unit cell (the smallest crystal possible)
@barrygoldman1 in this case, its lower energy for the crystal to grow along certain 'facets' of the crystal structure, so they form rounded edges. That's oversimplifying it a bit - these are grown at 1000C at low pressure - so there's quite a lot going on!
@barrygoldman1 Sorry! I still need to work on my communication 😉 The field I work in is Nanotechnology - although it's super broad. This is a (high T) crystallisation reaction, so falls under physical chemistry - wiki has a decent summary - but it's quite technical: https://t.co/xiUOzOpQYe
@barrygoldman1 Geodes are from solution. These are grown from vapour at around 1000C, I'm not confident enough to ascribe it to a simple rate (i.e. fast = fractal or slow = fractal)
@barrygoldman1 There area lot of competing factors - these are also not homogenous pure crystals - they're a solid solution of Cu and W with some S thrown in - so their stoichiometry varies wildly. These were also cooled quite rapidly, from 1000C to 25C in about 15min - which has a huge impact
We're getting towards the end of the week and ticking off topics ☑️✅✔️ Today I'll be talking about my favourite - assembling or 'structuring' nanomaterials 🗼
Before we start - let's talk about why nanomaterials are so impactful for research 👩🔬and society👨👨👧👧 Then we can start talk about how and why we put them back together!
When you take a large material and shrink it down to have nanoscale dimensions - quite a few things change - even if it maintains it's same shape. One of the biggest things is a dramatic increase in surface area 👇 https://t.co/N902sybB0V
This increase is hugely important because surfaces are: How the material interacts with its surrounding environment 🏝️ Where chemical reactions can occur ⚗️ High energy ⚡️- they want to merge together to form a lower energy system ❌!
This means as we make a material smaller, we can use less of the material but still have the same amount of chemical/electrical or device performance! https://t.co/Ps3JlUeFM3
As you enter the nanosize domain, your nanomaterials typically have a dimension that is close to the wavelength of light (~400-700 nm). This means you also start to get some really cool optical effects! https://t.co/nPqKpI3HnC
Stopping to think about it - having all this surface area, and ability to interact with light is super cool. ❄️ I already mentioned the high surface area means things want to combine together to form a larger material again. So how do we keep our amazing properties? Assembly! https://t.co/hiElxbJNCU
Starting with my old favourite! Carbon Nanotubes. I've already spoken about growing aligned carbon nanotubes via chemical vapour deposition 👇 https://t.co/SJUWTbWcwH
The aligned carbon nanotubes are amazing materials - but you'll notice that if you look at the top surface - there is zero space between adjacent CNTs. ❌ This is because of the strong 'van der Waals' interactions between adjacent CNTs leading to a tightly packed structure! 💪💪
This means all that beautiful advantageous surface area I introduced above - we simply can't access! Nothing can get between the CNTs to interact with them. ☹️ (these find great applications in membranes). ✔️
However, by changing the growth process just slightly (adding in some Sulphur) - we can stop these materials stacking together - and suddenly we have a lot of free space and can access all the surface area of the carbon nanotubes! I've added a photo to give size context as well https://t.co/94Tc0rXFjV
This free space induced by our growth method is really important if you're looking at electrochemical energy storage devices. For those not familiar, supercapacitors, fuel cells, and batteries all rely on the interface between an electrolyte (containing ions) and an electrode.
The ions in the electrolyte need to be able to move freely in the device in response to either a load (discharging) or energy input (charging). Diffusion is a physical process - so having this open pore structure lets ions move much more quickly! So we can charge much faster! https://t.co/aNfLGVH8AF
CNTs are great by themselves, they're electrically conductive, strong, and chemically stable. ☑️✅ However, if you're looking at something catalytic - like a fuel cell or water splitting - you typically need an active material. You can probably guess - metal nanoparticles! https://t.co/hR1h2MVjF3
Getting metal nanoparticles into this free space between carbon nanotubes without clogging all the pores is tricky! This is why I put all that effort into producing them super quickly using microwaves.
Since microwaves interact strongly with CNTs - we get metal nanoparticle reduction *only* at the interface between the CNTs and the solution. Meaning our pores stay open!! 👇 https://t.co/cXGTZwzowB
So our overall process ends up looking something like this 👇 And the furnace was pretty hot! https://t.co/Fpj1rNVqFZ
So why do we care about all of this at the end of the day? Well the catalyst for fuel cells is platinum - platinum is expensive and scarce. Using our method we reduced the amount of platinum needed to run a fuel cell by a factor of 10!! https://t.co/T9jhaoNZqs
This is super cool - but it's still a flat film? What if we want to do this on complex structures. Well we can - by a complex substrate with precursor we can grow these same structures over nearly anything! Steel substrates 👇 https://t.co/XHxPcPrpXR
Carbon foams 👇 (https://t.co/FCsgLYUdlF) https://t.co/hnhcoGh7qr
or even (carbonised) paper! (https://t.co/en8vRZb7xm) https://t.co/V1ZUGgJU3q
I'll be back in a little bit to talk about assembling different types of nanomaterials and what we can do with them!
Lets get back into it! I've spoken a bit about electrochemical energy storage - what about the optical side of assembling materials? 👁️ https://t.co/h9KtGiNWo6 https://t.co/JLxUOmRjH4
One of the interesting things about the hydrogen economy - is the huge abundance of water 🌊. Of course, lots of that water is salty which makes splitting water into oxygen and hydrogen quite difficult.
There are a few ways you can split water: electricity ⚡️ (electrolysis) electricity ⚡️+ a catalyst 🐈(electrocatalysis) light 🌞+ electricity ⚡️+ catalyst 🐈(photoelectrocatalysis) light 🌞 + a catalyst 🐈 (photocatalysis) My assembly work is around photoelectrocatalysis
The catalysts role is to lower the energy needed to split water. Adding light or electricity can provide any energy still needed to either allow the reaction, or make it happen faster.
All of this will still happen in solution - so everything I talked about before - diffusion to and from a nanomaterial - is still crucial! You also need lots of material to make enough hydrogen to be worthwhile!
So 2D materials for water splitting, how do we structure these. The first work we did was driven by the brilliant @Budinelli - making thin films of two different transition metal dichalcogenides (MoS2/WS2) 👇 https://t.co/EXb8XI64sZ
This work (that we published here: https://t.co/WBf5bGAxAu) - showed the first use of TMDs as photoelectrocatalysts for water oxidation✅☑️✔️! But it had problems Low efficiency ❌ Low overall current ❌
So what happens when we take a 2D film of these materials, and take it into 3D structures? Our efficiency goes 👆 Our total current goes up 👆 Why? https://t.co/sJMQ0Krojb
Well basically for 2 reasons; 1. having a rough surface causes light to bounce around more, so a photon that's not absorbed intially can be absorbed by another part of the electrode 2. a much better contact between MoS2 and WS2 - meaning charge can move in the system easier! https://t.co/TCGhQ8wezR
I'm running a bit late today but I'll be back to finish this thread soon! If you're interested in reading more: https://t.co/TUeOjJh1pC
Running out of time for what I wanted to talk about this week ⌛️ Lets get back into assembling nanomaterials and how we can use these to harvest energy from motion! 🏃♀️
One of the really cool things about nanomaterials - is because of their high surface area ratio - you can put a tiny amount of them in a different material, and dramatically change that materials properties 📈! Stronger ✔️ More conductive ✅ Change the crystal structure ☑️
The crucial thing to understand when adding a nanomaterial into a different material - is how they interact both chemically ⚗️and electrically ⚡️ If you can control these interactions, you can make your new composite material have amazing properties!
The easiest nanomaterial to talk about this sense is either carbon nanotubes 🗞️or graphenes 📰 These are typically pure carbon when they're made, but can be easily functionalised with oxygen, nitrogen, or even sulfur groups - making them more water loving or 'hydrophillic'
This is really important for electrochemical storage devices - because you want the electrolyte (which can be either water based or an organic chemical) to want to touch the surface of the nanomaterial. 👇 is a drop of water on pure, or oxygen functionalised carbon nanotubes! https://t.co/f6HILnQ69f
A similiar effect happens when you mix nanomaterials with polymers, how the polymer 'wets' the nanotube is crucial for a good transfer of properties. https://t.co/Ob1e47yZv8
The polymers we're particularly interested in mixing nanomaterials with are 'piezoelectric' polymers. These polymers can change mechanical force (like running 🏃, vibrations 🔊, cars driving 🚗) and make electricity from it!
To reason these polymers can convert mechanical to electrical energy is they have an asymmetric structure. The most common type of piezoelectric polymer is polyvinylidene difluoride (PVDF). 👇 https://t.co/bEQlJB4A7A
But just being asymmetric isn't enough, they also need to be arranged in a certain way (the Beta/Gamma structures above) 👆 And then these arrangements need to be aligned within the whole film! 👇 That's a lot of control needed from the nanoscopic up to the macroscale order! https://t.co/1SAm64E2OZ
I'm not going to go into detail here, there are some great papers out there if you really want to dive into the science of this including from our own groups @ShepelinN https://t.co/xp87pNfjZ8
What we try to do with our nanomaterials is control how these domains of polymers are aligned. So we can save loads of time ⏳, energy ⚡️, and money 💰 in making these materials.
We used a modelling tool called molecular dynamics - done by the amazing Dr Eirini Goudeli (https://t.co/veTjua0L8F) - to show that if we add just a tiny amount of carbon nanotubes into our polymer we could control how the polymer assembled on a macroscale!
Check out our beautiful dancing polymers along a carbon nanotube 👇👇 (from another of superstar @ShepelinN papers: https://t.co/yiD23OISPl) https://t.co/T0oI9iQZxt
If we do this we can make polymer patches in 30s for around 0.4AUD each that can make voltage from a finger tap over 100s of cycles - even able to charge a capacitor! https://t.co/DFOE5tHqBH
We showed that this effect wasn't because of a change in crystallisation of the polymer, we didn't have more beta/gamma than without nanotubes - rather it was the way the nanotubes and polymer aligned together made all the domains point the same way! https://t.co/JIf3CmKses
The next steps for us are to figure out how we can do this better - improve the assembly of nanomaterials, by changing the chemistry, geometry, and type of material! But - I'm not ready to talk about that bit yet 😉
I'll be back for my last curation day tomorrow to talk about my perspective on research in a COVID world, and try to give some tips for aspiring researchers! https://t.co/bzXDSbOksG
I've been a bit slack finishing up 📰📜🧑💼- so this will be my last thread from this account. I hope you've enjoyed the topics I've covered and please ask me questions @NanoIn3D about anything! Lets get into: 1) Research in a COVID world; and 2) Advice for new scientists! 👇
This year has been like no other. (Obviously). It has disrupted every industry to some degree Academic research is no different, my perspective is tinged from 🇦🇺Australia but there are common threads globally that tie it all together. 🌏
Lets talk about immediate impacts ⏲️ 1. Researchers unable to access lab facilities This is the most obvious problem - the pipeline of experiments that flows is disrupted. People can keep generating outputs from previous data, but in 2021 and 2022 scientific reporting will drop.
2. Significant delays in shipping ordering chemicals Even when we get into the lab - getting anything is super slow, this makes planning - already ridiculously difficult at the moment - even harder
3. Increased teaching load giving remote lectures. Each hour of lecturing takes 2 to 3 times longer to do remotely than to do face to face, this increase further takes away from researchers time doing, well, you know, research! 🧪
Those are immediate, not including the huge mental health and anxiety challenges that are exasperated by the pandemic. Academia already has a disproportionally high rate of mental health issues. This needs to be addressed separately from the pandemic.
Slightly longer term: 1. Decreased enrollment numbers - means less student fees and less institutional funding for research AND less for research support - administration that is just as important.
2. Decreased access to undergraduate students - means it's challenging to recruit new Masters and PhD students into a lab. Couple this to:
3. Closed Borders - means getting international students in is nearly impossible right now. Again there will be a flow on effect in a couple of years from this. Students are finishing, there are very few to replace them.
4. University job losses - in the Australian sector these have been massive. We can't quantify them because of the casualisation of the workforce (another problem that needs a separate thread) - but even the fixed term/continuing staff that have been let go is a huge number.
This has all been negative so far, well unfortunately the pandemic has been pretty damn disruptive to scientific research, and government funding cuts/exclusion of universities from government pandemic support has made this worse.
There are positives through. (Australian) Universities have been brilliantly positive in allowing people to work from home, we are able to keep getting paid, and work remotely - this is likely to continue into the new year.
There has been a boom in virtual conferences, allowing those who would otherwise be unable to travel able to access a much bigger pool of events. Anything that helps inclusivity in science is important to preserve.
The constant 'Zooming' means there is very little difference if a collaborator is next door or halfway around the world - so it's easier to work with people globally.
There are lower expectations. Science glorifies overworking, sacrificing everything for your 'passion', and a false belief that 'if there is a will there is a way' (there just isn't in the competitive nature of research funding sometimes - rejection isn't a reflection on you).
The pandemic has helped shift this (in Australia), people understand the challenges (like in my case daycare being closed so having a 2 year old climb over me constantly). Whether Institutions recognize this career interruption long term is a different story. https://t.co/ArZspoUR5c
The pandemic has brought massive challenges to academic research, those changes will be felt for the next 10 years at least. You quite simply can't turn it on and off like a tap. It's a pipeline of skilled people who leak out of the system when the tap is off.
Right - away from that gloom! Advice for up-and-coming researchers 👇 https://t.co/Sf62szT47n
My biggest advice is always two things: 1. Find research you really enjoy, a topic you're interested in, or tasks you like doing - pursue that. There are benefits to academic life - but the pitfalls are so much worse if you're doing something you dont enjoy.
2. Find out what the group leader is like to work for, a good group leader makes your work enjoyable. A negative group leader will crush you - if you're applying for a Ph.D. this is particularly important, have a chat to previous Ph.D. students.
Apart from that it's about being proactive from the first day you step into research, apply for grants you're eligible for, be selective about (but definitely get involved in) relevant societies.
and finally, put your face out there - talk to everyone. Network, network, network. Academia has a lot of nepotism (it's getting better but...) - getting to know people will give you an advantage in the job/PhD hunt.
Don't make assumptions about who someone is, take the time to meet and talk to everyone you can at conferences/events/meetings - you never know when that person next to you might be your best collaborator, or a future employer/industry rep interested in investing.
I'm going to leave it there - I've enjoyed talking and interacting with you all! Thanks to @MySci_PK for giving me the opportunity to do this! https://t.co/B3ldSyetD8
[admin] Thank you Peter for a wonderful week of science about nanoavengers 😀 Do give @Nanoin3D a follow! Podcasts where Peter talks about his work are here - #87 https://t.co/ULNnbY9LzS #88 https://t.co/9BQjpuo6SY https://t.co/RjXzFzesFa
Cornelia Hofmann
[admin] "Fastest Experiments in the World with Electrons & Lasers" Please welcome @coenneli and listen to the podcast to know what is coming your way this week https://t.co/bTkVbaXKN6
Hi, Cornelia Hofmann (@coenneli) at the helm for this week 😃 No, I didn’t start on the #VendeeGlobe2020, I am a theoretical physicist in strong-field attosecond science, aka shooting atoms apart with very short laser pulses. But I don’t have cool lab shots, so here we are 😉 https://t.co/9d05tQj9pE
Let me introduce myself and my background a bit, before we dive into all that jargon up there. In February of this year, I started a new postdoc fellowship from @snsf_ch at @uclmaps. Before coming to London, I got my BSc, MSc and PhD all at @ETH_physics in Zurich,
and then had a postdoc position at @maxplanckpress Institute for the Physics of Complex Systems in Dresden. And yes, most of the time my “complex system” consisted of a helium atom and a laser field. #womeninSTEM https://t.co/XYxFmGIGO5
Besides doing research, I enjoy teaching on various levels, be that participating at outreach events demonstrating mind-boggling laser experiments, taking high-schoolers to an astronomy observatory, or teach and supervise students at the university level. https://t.co/BDxZvZYokg
As hinted above, sailing is a dear hobby of mine, even if I can’t do it as often as I'd like. Additionally, music takes up a lot of my free time. I played in orchestras, conducted ensembles, sang in choirs, love to play the piano, and listen to a variety of artists and genres.
So, what am I going to talk about during my takeover? Here’s my current plan (I might adapt it, depending on your feedback and responses): Later today I will give you an introduction to my field of research, scale you down from the world of nano down to atoms and electrons. ⚛️
On Tuesday and Wednesday, I intend to talk about some of my research projects, grouped by theme. Hopefully, this will lead seamlessly over to a discussion of the bigger picture, possible applications, and long term goals of this kind of research on Thursday.
Friday will be dedicated to more of my personal views and experiences so far on my academic path, and on the weekend we can hopefully come to a lighthearted conclusion.
I hope you will find some interesting tidbits over the course of the week. Most importantly, feel free to ask about anything, so I can freestyle and/or adapt my future threads 😁
Right, now, on to attoscience (which combines #quantum #physics with #ultrashort #lasers). First, I dusted off an overview slide of my thesis presentation. Attoscience studies electron motion in bound states, ionization processes, charge transfer, and similar. https://t.co/IDKAncL5Ir
All of this happens on the time scale of attoseconds, 10⁻¹⁸ seconds (and sometimes femtoseconds = 10⁻¹⁵ s), which is almost unimaginably fast. In the short intro podcast with @the_ScienceTalk, I explained the comparison with the age of our universe. https://t.co/LRsB1gNSff
To measure such fast dynamics we need an equally as fast tool, which is laser pulses of a few femtosecond duration or shorter. Because a lot of energy is compressed in a very short time, the peak power of these pulses can reach terawatts (similar to nuclear power plants). 😲☢️ https://t.co/dkE1aAaLW2
These high intensities of the electric field can then compete with the binding Coulomb force in atoms (and molecules, larger structures, ...) and not only mess with the energy levels, but also cause ionisations. https://t.co/AHhoOphqBD
Now you might wonder, what on earth does that have to do with nanoscience? Well, in my personal research, I have exploited the interaction of nanostructures with the laser field to create various spatial structures in the electric field. But more on that later in the week.
Besides that, attoscience is concerned with understanding the dynamics of electrons in various materials, the field has started from studying atoms, to include molecules, surfaces, semiconductor structures, liquids…
You see where this is going? I talked a bit more about that in the @the_ScienceTalk podcast which will be released on Wednesday 🤗
@MySci_PK I did once help out in a science fair where our booth was titled "faster than what the police allows" 😂👮 (in German) https://t.co/S8C9MAMBf3
Hello everyone! To talk about my research, I decided to theme it by "studying the ionisation process itself" (today) and "possible things that can happen afterwards" (tomorrow). https://t.co/ABoN1AJ5yO
I'm going to keep the explanations in the threads fairly colloquial. But I will link the corresponding publications (open access whenever possible) so you can dig into the details there if you wish. Or of course, just ask me any questions you might have and I'll expand on that 😉
Yesterday I have already introduced the idea that the strong electric field of the laser pulse modifies the Coulomb potential which keeps electrons in bound states. The video shows a classical picture of this: https://t.co/VhfiL03IlZ
However, we are actually dealing with a quantum system, and for typical strong-field parameters, most of the ionisation processes happen by quantum-tunnelling through the potential barrier https://t.co/gzh0A961nb
One of the key questions which is still being investigated in detail is then, what the electron wavefunction looks like at the end of this tunnelling process. Does it have some momentum? How wide is its spread? https://t.co/UINPh87MuJ
These characteristics are important because they determine where the electron (probability distribution) will go subsequently, and this is precisely what is measured at the end on a detector. (video not mine) https://t.co/BjnG6vdTkg
By comparing simulations with different momentum distributions along the tunnel-ionisation direction against a set of experimental measurements, we found that the (previously common) assumption of (almost) 0 momentum along that direction is not a good approximation.
publisher version: https://t.co/OmJqLly5lY open access (OA): https://t.co/5YrHVTZ84l
And this finding is independent of whether we are in an adiabatic regime (i.e. the wavefunction can always instantaneously adapt to any situation) or non-adiabatic (i.e. the temporal evolution matters) https://t.co/Wha2Ir9xua OA: https://t.co/hBQfCBSIZC
Another key question is: "how long does this process take?" ⏲️. At first glance, this might sound like a straightforward question, but since the phenomenon of quantum tunnelling has been discovered almost 100 years ago, there has been a debate about this. https://t.co/ahfToRizYk
So, #attoscience tries to time-resolve electron dynamics, where one of the dominant processes is quantum tunnelling 😉 Of course, our field developed both additional theories and several experiments to try and measure the/a tunnelling time https://t.co/krsPPMHHWD
Most commonly, the laser field is elliptically polarised, so that the electric field rotates around like a clock, but still has clearly defined moments of strongest field leading to highest probability of ionisation https://t.co/VR1hG4PPxl
The interaction with the laser field after ionisation imprints the moment when an electron exits from the potential barrier onto the final momentum direction. This moment appears to be later than the maximum ionisation probability moment. (first image: https://t.co/FKP8c2Pw9I) https://t.co/XYgCwLL1Lb
Unfortunately, this "exit time↔️final momentum" mapping is disturbed by many factors, such as the Coulomb attraction of the parent ion, momenta/energy at the tunnel exit, and more. This debate still continues... https://t.co/PGuFaqnNMR
about me: https://t.co/kxln6Un7GI
Quick Crash Course to the research field: https://t.co/FYxsuHWMEk
Investigating strong-field ionisation itself: https://t.co/D3JuyrYTRC
[admin] "Fastest Experiments in the World with Electrons & Lasers" Extended conversation with the amazing @coenneli is out now - https://t.co/KshjnOP5Jy
so... life is what happens while you're busy making different plans... In my case, this applies to quite a few of my career steps along the way. But also most recently: a plumbing accident/failure upstairs flooded my apartment late yesterday evening 🌊.
Basically, i just wanted to let you know that my thread later today will probably end up significantly less detailed than yesterday, as I am still busy dealing with that.
Anyway, if you're curious about my path in academic research (or some research environment discussion, and how my research connects to material science) please do check out the full length podcast 🤗 https://t.co/vklnYfiLaX
Good evening! While my fan heater is doing its job, why don't we catch some electrons? https://t.co/yDtMYkK43p
In yesterday's thread, the electrons which have been freed from their bound state by the laser mostly just oscillated around (steered by the electric field) and eventually flew off and away (until they hit a detector). https://t.co/h7dlDy6I3e
However, not all electrons are so lucky. For some of them, their trajectory ends up looking almost like that lasso up there. This is if their kinetic energy at the end of the laser pulse is not quite enough to escape from the Coulomb potential of the atom/ion. https://t.co/FAfAJGaFIc
The nucleus is marked by the "x" at position (0,0,0). The electron exits from the quantum tunnel (beginning of the red dotted path) and starts oscillating in the laser field until it ends up on an elliptical, bound trajectory (blue dotted) once the pulse has passed. https://t.co/GQOBX6kbYJ
The blue bound trajectory looks like a Kepler orbit, because the maths is (almost) the same: Planets are kept on their elliptical orbits by gravity, while electrons are bound by the Coulomb attraction with the ion (except, one is a quantum particle and one clearly isn't 😉). https://t.co/HAvUyyEGiY
Therefore, the final fate of these types of electrons is a highly excited bound state aka Rydberg state. And if we look at the entire process as one, there is no actual ionisation happening, in the end, we are left with a neutral, but highly excited, atom again. https://t.co/L4c6O4SiSV
I should probably also mention the units on the plots: a.u. = atomic units. Our preferred units because all the important reference quantities of an electron are set to unity. 1 a.u. in length equals the Bohr radius, approximately ½ Å.
If the laser is polarised linearly (or only has low ellipticity), a significant part of all tunnelled electrons ends up in Rydberg states. We can then use them for different purposes in our investigations, for example:
taking them as a reference point to study shifts in the photoelectron momentum distribution https://t.co/1recHd4UrH (OA: https://t.co/BNvcGloutm)
or searching for (and finding) non-adiabatic effects, meaning that the dynamics of the process is relatively fast and the wavefunction reacts to the entire temporal history rather than only a given instantaneous situation https://t.co/ZrVAVVjINZ (OA: https://t.co/D5fN8oHVIB)
Tunnelled electrons which don't manage to escape from their parent ion: https://t.co/dcxifHkzFK
It is evening again, and I finally find a moment to check in here. How are you doing?
I feel like my apartment has turned into a bit of a "sauna for beginners": higher room temperature than I would usually keep in wintertime, and more humid than usual in general (despite having open windows)...
I'm going to switch my plan around a bit. The exciting opportunities for future scientific and technological developments derived from #attoscience (and if I find the time, a project using nano-objects to modify the spatial dependence of my laser fields) will come later.
I already mentioned that I started my current position in February of this year. I moved from Dresden, Germany to London, UK at the end of January (yeah, I made it in right before the Brexit date). You can probably already guess where this is going...
I barely managed to find myself an apartment and scramble together a livable household by the time the first lockdown hit. On the afternoon of the first day when our group went into full-time home office, I finally got an internet connection installed.
(okay okay, you might argue about just how livable an apartment is that just got flooded 🤔🤭🤷♀️)
The plan of how the start of my new position would go did definitely not pan out that way. And having to settle down in a new country while in a lockdown created some unexpected additional challenges.
For example, my new GP practice sent me a form to be filled out and signed when I wanted to register with them. Only, I did not have a printer at home and I was not allowed on campus any more. Thankfully they accepted my digital scrawl 😆
Another effect was, that I barely got to know my new group (PI @CarlaFMFaria, my sort-of predecessor @DrAndyMaxwell, and colleagues @AbbieBrayPhys and @heloise_cho), let alone other colleagues in the institute before we were only able to see each other through screens.
So that definitely didn't help to mitigate the impact of the pandemic on my work productivity and how I was able to deal with all of it. Thankfully, we managed to strike up not only work meetings but also social meetings,
be that a regular socialising coffee/tea break with the entire group, or late-night online game sessions to just have a laugh from time to time (thank you @AbbieBrayPhys !).
As much as we're all trying our best to develop personal strategies to better cope with the increased pressure/mental health impact/loss of structure/health challenges/... and additional grievances of this year, it remains to be seen how this impact on our work
... will be taken into account down the road. I am mentioning this particularly from the point of view of a postdoc on a short fellowship (2 years), needing to be able to find a next position soon again in this nomad-academic stage.
I am very grateful that already in March @snsf_ch reached out to us fellowship holders and informed us that they are introducing an option to apply for an extension of the fellowship term, on account of reduced productivity due to covid19 impact.
Still, how will future hiring/grant decisions weigh such aspects? At this point, I don't have any good answers. But I expect that a standard phrasing on CV's explaining a certain publication/citation/output break or slump will probably develop for many of us.
This was quite a different kind of thread from what I have done here before. Unlike my brother, I'm not a health expert. So I am in no place to judge the recent news about a possible effective vaccine. But even while telling myself to remain patient, cautious, and careful,
having that metaphorical carrot dangling in front of me did feel like a happy relief as we are moving towards the end of this year (and currently working through renewed lockdowns in many places).
I hope and wish you are all doing as well as you can considering the circumstances. Take care 💜 https://t.co/xO3j0Q9NTx
moving to a new country by moving into a lockdown: https://t.co/2hh8iKmFUJ
Hello again! https://t.co/ulpPuRrhW4
I have this itch to swing back to talking about physics after yesterdays more meta thread, much like a pendulum always striving towards the middle position, but constantly overshooting. BTW, pendulums are an excellent representation of how short laser pulses are created! https://t.co/oDO2eRyvYq
You have probably heard (or learned) that laser light has a very defined colour (one specific wavelength/frequency), and all photons are in phase with each other, all their waves are perfectly synchronised (coherent). (Image source: https://t.co/ad2csUMm1u) https://t.co/hg0vR934iE
However, if we only allow one single wavelength, then the laser light is continuous. Only when we add up several slightly different wavelengths (or frequencies) do we get a short and intense pulse, right at the moment when all those different waves happen to align with each other https://t.co/9iDFGM7JGG
Before and after, when all the different contributions are not perfectly aligned, their individual troths and peaks partially (or completely) compensate each other. https://t.co/X4Nn0k1TWS
Obeying the laws of the Fourier Transforms, shorter pulses require a broader spectrum. And ultrashort pulses consequently require a very broad spectrum, which means only very few lasing materials can be used to create these. [https://t.co/7lC7vUJ2uH]
With Ti:sapphire lasers, the pulse duration can be around 5 - 30 femtoseconds (fs). For the attoclock method, this is fine because one rotation of the field is around 2.7 fs, giving attosecond resolution in the angle. https://t.co/ioQWdW4Gdu
But for most other methods, we need pulses which are themselves shorter than one femtosecond. We are exploiting an effect which is part of strong-field physics: High Harmonic Generation (HHG), which converts infrared photons of a fs pulse into extreme ultraviolet (XUV) photons. https://t.co/16JwRTPZmo
The key components of HHG are beautifully demonstrated in this video by the Photonics and Laser Applications Group of University of Salamanca, and JILA, University of Colorado https://t.co/dJmHms6MGr
In my own research, I have 1⃣ looked into phase-matching: How coherent are the different XUV photons which are being emitted by all the recombining electrons distributed in the gas cloud? https://t.co/ugryUi8XzC
and 2⃣ also played around with: what happens if the laser field is a mix of two very different frequencies creating a fancy pattern? And if additionally, you have nano-particles nearby, creating a spatial dependence in the laser field? (second image: https://t.co/WYcVpxYaHc) https://t.co/D4AwqyBHwY
(yes, this is me actually talking about something nano finally 😉)
The three-fold symmetry is imprinted onto the typical paths that electrons are taking (first image). But with the spatial dependence on top, that symmetry is completely broken (second image), and the energies with which these electrons are recombining are vastly different. https://t.co/HZd5JlHs8m
Preliminary results of this investigation are on arXiV: https://t.co/WwFYp4SKQ5
back to physics: What exactly is laser light? How do we create our ultrashort pulses? And what about those nanoparticles? https://t.co/ze753lXIs4
oh, I forgot the source for the pendulum laser movie! here: https://t.co/u9PAtNWaSe
Hi everyone :-D We have reached the weekend already. Over the last few days, I hope I managed to give you a small glimpse into my research field. But one promise I have not yet delivered on: Where will all of this lead? What's the point? https://t.co/42NTKJZwa7
First of all, I don't think I have to convince you that the quantum tunnelling phenomenon is found in all kinds of fields. Recently I came across a paper discussing tunnelling times during a photosynthesis cycle in an organic molecule. https://t.co/3TYV78sUPV
Many might be familiar with Scanning Tunnelling Microscope (STM) technique to investigate surface structures with (sub-)atomic spatial resolution (or make an atomic stop-motion movie 😄) https://t.co/kMEaFwxdFm
And an example of future innovation development is in transistors for electronics, where quantum tunnel leaking is currently presenting a limit on the miniaturization, and dedicated quantum transistors could present a new breakthrough. https://t.co/LwVO0AIF1p
There are of course many more fields and technologies. For any of them, new insights gained from #attoscience about the quantum tunnelling process itself can deliver new puzzle pieces.
Another aspect: we study electron motion. And understanding charge transport (usually electrons moving from one place to another) at the microscopic level for example in heterojunctions of photovoltaic cells allow a possible new pathway of trying to improve their efficiency. https://t.co/ULzYm6M3yy
More and more aims move from "observing" to "controlling" electron dynamics with tailored fields. This invites dreams and hopes of controlling electron dynamics for example during chemical reactions, taking femtochemistry (dynamics of nuclei) to the next level. https://t.co/qIEHb83LBS
Obviously, there are also more applications within #attoscience itself, where we're using the photoelectrons or emitted radiation as a secondary tool to investigate for example dynamics in molecular orbitals, and more. Some of the applications I have listed above are ongoing
already, others are still hopes, dreams and ideas. A lot of work still remains to be done, both by the attoscience community and also all related fields. After all, we're still a very young, exciting and growing field 😉 https://t.co/4cBH7CX5zr
Where will all of this lead one day? Ideas, outlook and applications: https://t.co/FgtY9xUe3m
Happy Sunday everyone! It has been an adventurous week (in many ways 😁). I recently came across this fun little #laser quiz and thought that would be a nice conclusion to my week here. So take a guess and play along 🤗 https://t.co/xqiWugyDcy
1. What does LASER stand for? a) Light Amplification by Stimulated Emission of Radiation b) Light Absorption by Simulated Emission of Radiation c) Latent Absorption of Specified Elliptical Radons d) Latent Amplification of Stimulated and Elliptical Radons
2. What particle plays the major role in the process of lasing?
3. What do you call an atom whose electrons have reached a higher energy state?
4. When an electron drops down from a higher energy state and recombines with a hole, what is produced?
5. Laser light has many features different to ordinary incandescent light. Which of these is NOT one of them?
6. What requirement needs to be met before a medium can begin to 'lase'?
7. What is the minimum number of energy levels needed for lasing?
8. The wavelength of the laser light depends on what feature of the medium? a) The density of excited atoms b) The energy gap between the excited and ground state c) The amount of energy levels in the lasing process d) It has nothing to do with the medium
9. What is NOT a form of laser?
10. In what decade was the first laser built?
And last but not least, because in the podcast I used some Astronomy/Cosmology fact to try to explain just how short an attosecond is, and I mentioned my interest in music... a fitting bonus questions:
🌟. Why is this song named after the asteroid number of Pluto? https://t.co/Rv6PzfomnE
I will come back later today with the solutions. But if don't want to wait until then... you can find them here, too: https://t.co/ug3LBFlQfV
A quiz to finish the week: https://t.co/fVCuUZqwml
(thread by @coenneli)
(thread by @coenneli)
(thread by @coenneli)
(thread by @coenneli)
(thread by @coenneli)
(thread by @coenneli)
(thread by @coenneli)
Laser Quiz part 2: here come the solutions: https://t.co/95CftIhMJr
1. LASER = Light Amplification by Stimulated Emission of Radiation (a) 2. Electron 3. Excited state atom 4. A Photon (I don't think there is a lasing material capable of producing gamma range photons) 5. Diffuse 6. Population Inversion
7. 3 Levels (with just 2 levels, as one approaches population equality, stimulated emission and absorption would start balancing each other out, preventing population inversion and thus there is no amplification of the light) 8. b) The energy gap between excited and ground state
9. Creatine (semiconductor structures can be designed so that they can lase) 10. 1960' (the first-ever laser, built by Ted Maiman using a ruby crystal, is still operational: https://t.co/zdJX6NCPXP)
🌟: Pluto losing its planet status and receiving an (impersonal) asteroid number was used as a metaphor for the alienation of an individual from a community or a significant other.
Here are some lyrics: "Without a name to myself, I still orbit you [...] There’s no name allowed for me I, too, used to be your star [...] My cold heart is at -248 degrees [Celsius] it stopped on the day you erased me" https://t.co/OAggKE7EBt
(thread by @coenneli)
It was a great week, thank you for the invitation and for following along, everyone. I'm sure you will have lots more fun with the upcoming takeovers, too 😁. You can find me at @coenneli if you wish. With this, I say thank you and goodbye. https://t.co/jjk7975b2K
quiz solutions: https://t.co/wDWGyRnwmt
[admin] Thank you @coenneli for a wonderful week of attoscience! Do give her a follow! Podcasts where Cornelia talks about her science are here - #89 https://t.co/bTkVbaXKN6 #90 https://t.co/KshjnOP5Jy https://t.co/kNLGmbn0W7
Chris Spicer
[admin] "A Chemist's guide to the Nanoscale" Please welcome @spicerlab and listen to the podcast to know what is coming your way this week https://t.co/fxraCjhPJN
Hi everyone, Chris Spicer (@spicerlab) from the University of York in the UK here, taking over the account for the week. Really excited to talk to you all about chemistry, nano science, and my life as a researcher over the next 7 days!
We've got lots of things planned for the week, but we'll be starting off with the story of how I've ended up where I am today
Right, where it all began - as I started typing out this chain I realised I was giving hackers a ready made guide to those annoying password questions you have to answer about your first pet's favourite colour, so I'll keep the first 18 years of my life brief!
Born in the North of England, moved to the South when young - retained a love of gravy and football, and a hatred of ballet (poor satirical joke for the UK followers, #jakeberry). Enjoyed chemistry, biology, and maths at school, but had no idea what I wanted to study at uni. https://t.co/XSlxxTrkzt
So I ended up studying Natural Sciences, a real mish-mash of anything and everything science-related for the undecided! I loved the freedom I had to study evolution one day, thermodynamics the next (that's a lie, I hated thermodynamics and still do, but I did enjoy evolution).
There aren't that many universities in the UK that offer Natural Sciences courses still, but for young people who aren't sure what they want to do and don't want to be pinned to a decision yet, they're a great option. In the end, I specialised in chemistry and never looked back https://t.co/FLMZc77IAz
After a Masters project with @OScherman I moved to @OxfordChemistry for my PhD (weirdly called a DPhil there). Looking back I was so naive about the project I chose, I was basically woo'ed by a 5 minute conversation about how powerful chemistry was as a tool to control biology.
But I got lucky and ended up on a great project, using transition metals (mainly palladium) to do some really cool chemistry on proteins. There are loads of reasons to want to do this, like attaching drugs to proteins that can deliver them around the body to treat disease or...
making certain parts of a cell light up so we can study how these amazing building blocks of our bodies really work, or to allow us to make tests that can diagnose diseases really fast like a pregnancy test.... the list is endless
While there I was lucky enough to work in a lab with lots of amazing scientists: @ChalkerChem @Keribackus @charlogauthier @goodfellow_jj They probably don't realise it, but these people really influenced the way I approach science and I'm incredibly grateful to them!
Give these people a follow if you want to learn about some really exciting science (less so for @goodfellow_jj but he does have the world's cutest dog). I'm sure there are many more I've either forgotten or aren't on twitter, so sorry to them!
After my PhD I realised that while I loved the research I'd been doing, I wanted my career to be a bit more applied, developing the actual technologies that were going to make a difference to people's lives, rather than the key fundamental studies that would one day get there
So I moved to @imperialcollege for a postdoc in bioengineering. This is where my love affair with nano- and materials science really began. https://t.co/kUVtzd7NT0
This was a big change in field for me and I was massively out of my depth - it was challenging at times, but I realised quickly that looking at a topic from the perspective of a complete newbie with a different set of skills could be a really useful way to do innovative research
Having a different viewpoint is invaluable, and you should never be afraid to try and learn something new, ask a lot (I mean a LOT) of questions, talk to people in completely different fields to you - push yourself outside your comfort zone and you'll be amazed what can happen. https://t.co/IbzHUUCynp
After 3 fantastic years, I embarked on a new adventure @karolinskainst in Stockholm. My postdoc group had recently started a new satellite lab out there, and I had a fantastic 2 years in this unbelievably beautiful city with @GormleyLab @ChristineHorejs @derrick_a_rob @woodc1881 https://t.co/Vr6FYAy4MV
Learning a new culture (albeit one very similar to the UK with added coffee and fermented fish), a new way of working/researching, and making many new friends was an unforgettable experience, and I miss Sweden a lot, especially the snow and the days that the sun doesn't set!
All of this led me back to the UK 2 years ago @ChemistryatYork to start my new position as a Lecturer (Asst. prof. for the Americans). Having the opportunity to start my own research group has been amazing, and you'll hear all about what we're up to over the next few days https://t.co/qUtdHwJX1L
But to finish a very long thread, here's a quick summary: Started as a chemist, learnt a bit of biology, got drawn into material and nano-science, learnt a bit more biology, and now run a group doing a mish-mash of all of it, back in a chemistry department where it all began!
Hopefully that gives you a flavour of what you can expect to see over the next 7 days - it will be very varied, but I'm looking forward to it and hope you all enjoy the ride!
A new thread and some fun facts on where I am now, the beautiful city of York. Hit the motorway, follow the signs for The North (these actually exist in the UK), and keep going. 2 hrs from London or Edinburgh on the train, about 1 hr to Manchester, but that's the boring stuff https://t.co/djFSsot04b
But why would you need to travel when York has so much to offer? 1. York Minster - one of Europe's biggest cathedrals and also one of its most beautiful. The Minster dominates the centre of York, you can't miss it and a tourist must see https://t.co/zQW8lAPO0M
2. The Shambles - York city centre is packed full of small little Medieval streets, but the most famous is The Shambles - the setting of Diagon Alley, everyone's favourite place to buy their wands, broomsticks, and potions. Busy by day, stunning by night https://t.co/Vt7JootYdT
3. York City Walls - The walls have been around since Roman times in one shape or another, and are mostly intact. You can take a ~2 mile walk around them, giving stunning views of that pesky cathedral again https://t.co/wjC2QHP9Ec
The gates in the walls are all called bars - Mickelgate Bar, Walmgate Bar, Monk Bar.... They sound unique but a nightmare when you're new to the city and trying to find your way round. Far too many bars
4. Quite literally - York supposedly has a bar or pub for every day of the year, ranging from upmarket and trendy winebars, through to old traditional cosy pubs. Coming here from Sweden, where a beer cost ~£7, I was amazed to be able to buy a pint at my local for £1.50!
And nearly as many breweries - with the pubs shut at the moment a lot of local businesses are really struggling, so big shout out to @AinstyAles @brewyorkbeer @TreboomBrewery and many others who you can order deliveries from. Highly recommended for anyone in the UK
4. Speaking of which, how about the UKs number 1 independent high street @bishyroadnet? Full of amazing cafes and restaurants, hardware shops, greengrocers, butchers. York has an amazing independent shop scene that makes the city feel so friendly and welcoming https://t.co/icAg6nbUGR
5. York racecourse - home to some of the world's biggest races, and a great day out over the summer.... https://t.co/GWSVJg3NbI
And the beautiful Knavesmire when the races aren't on. There are loads of green spaces in York, as well as a beautiful river running through the middle. Ever so slightly prone to flooding, but we'll keep that bit quiet, the city's residents have learnt to deal with it. https://t.co/6UdF2Rn0Vi
6. Rowntree Park is another crowd favourite - when I first moved here we lived just off the park, and had a quick google to see if it was safe. Apparently not. You run the risk of being attacked by the 100s of overly friendly geese, as bad as it gets in York https://t.co/KHtkNjkCP0
7. Rowntree Park is named after the Rowntrees factory as a memorial to its employees who died in WW1 - chocolate and sweet making has always been big in York, not only Rowntrees but also everyone's favourite Christmas gift, the Terry's chocolate orange https://t.co/x1LukOeNXI
There are loads more great things about York - it's not just residents who think it's great, York is often voted the UKs best place to live! So next time your in the North of England, come and give us a visit. I'll buy you a pint. https://t.co/GmqpYoN5fN
@AinstyAles @brewyorkbeer @TreboomBrewery When I took over this account for the week this was the last thing I thought I'd be tweeting about, but since quite a few York people have liked the thread and followed - @AinstyAles your doing drive through collections in Acaster Malbis as well right??
I'm working from home a lot at the moment with the current restrictions, but today is a rare lab day so I'll be live tweeting what I get up to. First up, got to sanitise! Thankfully the mask covers the awful moustache that's coming along for #Movember https://t.co/GpbD2UpPG1
First task of the day is @spicerlab virtual group meeting. Today, PhD student Laetitia has set a problem set for the group to work through, got to keep our chemistry skills fresh! Look out for these lovely faces popping up over the course of the day... https://t.co/zj20HXKy5c
Next up is rejigging my 1st year lecture course on polymer chemistry for online delivery @ChemistryatYork . This is my current favourite slide - doing things virtually does have some benefits!Feels like a timecourse that represents my day so far. https://t.co/CnXsJZbZ4y
This is a course I inherited last year from @professor_dave - it's taught mainly through an independent learning work package that guides the students as they largely teach themselves. It's a great opportunity to get students to take responsibility for their own learning https://t.co/BtmR1jiY0u
And the best bit is the amazing videos the students make at the end on polymer chemistry. The students really throw themselves into it and get a chance to show their creativity. You can check out last years videos here: https://t.co/ScDg2DV60s https://t.co/JZjf1Ifsxz
@DrTinyTaps You'll have to sign up to the course and find out 😬 https://t.co/tLFO3PsWDu
@DrTinyTaps Though it does look like a storyboard of my day so far
@DrTinyTaps Does this convince you? https://t.co/BCkJh98j1M
On into the lab and the joys of insoluble molecules - its probably best that the facemask is covering up @spicerlab MChem student Natalia's expression. People think chemistry is all bunsen burners and explosions - WRONG. 95% of it is just trying to get stuff to dissolve 😭 https://t.co/ollnCumO3k
Here's PhD student Lydia teaching our biochemistry BSc student Greg how extract his product @ChemistryatYork. Tricky with masks, fogged up glasses, and at a distance but it looks promising. Fingers crossed for the NMR later - don't panic loyal followers, I will keep you updated! https://t.co/V4wXAnuMtD
@sarah2408 @spicerlab Thankfully this wasn't that bad! Bit of sonication and patience did the trick
@DonnaBlackmond I did! My future career as North Yorkshire's premier tour guide might need a bit of work still. A York(shire) institution and a classic tea room - best part is the mirror downstairs, inscribed with all the names of servicemen from when Betty's was converted into a bar during WWII
DISASTER HAS STRUCK! These were supposed to be some beautiful hydrogels to show you all, but something has gone badly badly wrong. Remember your daily sacrifice of a child to the science gods everyone, learn from my mistakes or feel their wrath. https://t.co/EmiySgW72R
In happier news, here is MChem student Taylor making some peptides. This machine is a workhorse for us, we can make a 10 amino acid peptide on a resin in about 3 hours. Doing the same thing by hand would take 3 days, or if not on a resin then about 3 months.#efficiency https://t.co/OeF6Kb9ZLj
Short peptides are pretty rubbish at pretending to be proteins. But they more than make up for this by being cheap, easy to make, and really versatile! The one Taylor's making is a substrate for a bacterial enzyme called sortase - watch this space.. (or more correctly @spicerlab)
And even happier news, here's PhD student Nick pretending to look pensive while really contemplating why Mo Farah has sunk to 'I'm a Celebrity'. The bright pink dyes he makes allow us to study really small amounts of chemicals just by shining a light on them. https://t.co/yPkjTHQQnl
@grumpymaterial That was just water that we used to try and rehydrate something that looked like it might have dried out 😭😭😭 This was a gel we thought we had nailed, so sure it is solvable
At the end of a long day in the lab, all that's left is to do your washing up. Chemistry really is like cooking at times, except a souffle won't spontaneously burst into flames if you open the oven too early. Could make @BritishBakeOff a bit more interesting next year though? https://t.co/9RYarrsxbN
@grumpymaterial I love it, this will be used a lot from now on!
One of the best things about my job is the flexibility. I can leave early to spend a couple of hours with my daughter before she goes to bed, and make up the time later on. Academia can be pretty intense, but this is a big bonus for me that I might not get in other careers
I know I'm very lucky to have this. My field of organic chemistry still suffers from an image of long hours, working weekends, and prioritising work over personal life. That's changing slowly, but there's still a long way to go
But for me right now, I don't mind doing a bit of work in the evening, it's a result of my choices to maximise my time with my family during the day. It works for me, but everyone's different. Flexible working arrangements are key to giving everyone the same opportunities
I'm lucky to find myself @ChemistryatYork where this is something the department really prioritises, and it rightly has a reputation for championing equality and diversity amongst UK chemistry departments
First thing this evening, the Ross and Rachel of the 21st century, the cliffhanger I'm sure you've been waiting to find out about since this morning - Did Greg's separation this morning work?! Does he have pure product??
HE DOES! It's not perfect but it's good enough for what we need. For the non-chemists each of the lines in NMR basically tells us about a hydrogen atom in our molecule - we can use these lines to build up a picture of what it looks like, like a jigsaw puzzle https://t.co/4Kc37i6xpx
Bonus point for anyone who can identify the molecule (or any portion of it) 😬😬
@NotHF Well that didn't last long - bonus point for Tim! Yes, it needs purifying up, this was just a quick work up, but to be honest for what we need to do crude is fine. We know what the other stuff is and we know it's not going to affect our next step, so better to purify then
Morning everyone, I realised that two days in to curating this account and I still haven't really told you all about what we actually do! So today I'll be tweeting mainly about our research - why we do it, how we do it, and also some shameless plugs of some of our papers
[admin] "A Chemist's guide to the Nanoscale" Extended podcast with @spicerlab is here 🥳 https://t.co/ZztOxHcPDe
Let's start with a very broad overview - our goal is to design materials that we can use to treat disease, specifically those where one of the tissues in the body has been damaged in some way. This encompasses things like heart disease, arthritis, nerve damage, and loads others
To do this the material should help us repair the damage, or replace the original function of the tissue somehow. This field is called 'tissue engineering', and the technologies it encompasses are really broad, from 3D printed organs, through to new tissues grown in petri dishes https://t.co/yWUJkJhteL
This is a super interdisciplinary field, populated by engineers, materials scientists, tissue and cell biologists, surgeons, polymer chemists, imaging physicists....... I discovered yesterday that it's even been used in Grey's Anatomy (though have to admit I've never watched it) https://t.co/4mAtglKblt
One technology is to use material 'scaffolds' that can be used by cells as a framework to grow new tissue. Just like the scaffolding on a new house. Except ideally this scaffold should not only be structural, it should also tell cells what to do so that they form a new tissue
Giving cells the right signals at the right times is REALLY hard. Nature is complex. We need to get way better at designing materials that recreate this complexity, but it's like having an IKEA manual for a Boeing 747. https://t.co/mtr4kcebPb
A lot of the 'tissues' we engineer therefore just can't function well enough to treat diseases in real patients. Tissue engineering has huge potential, but not that many technologies have actually benefited people suffering from these awful diseases yet
That's where we come in - we look at tissue engineering from a slightly different perspective, and look to use our skills as organic chemists and chemical biologists to see how manipulations at the molecular level can affect how cells behave at the scale of a tissue
If we can really control what's going on at the level of single molecules and how these interact at the nano scale, then we have far more chance of controlling what's happening at the level of something you can see and hold.
The grand vision is that we can then come up with better design principles, that then allow us to make better materials, that grow better tissues, that allow us to better overcome the symptoms of disease, and ultimately improve the lives of millions of peoples across the world. https://t.co/j9mXrYBxQQ
For the rest of the day I'll be tweeting some examples of how we do this, as well as highlighting some of the challenges we face both as a group and a community moving forwards.
@ahugumrah I couldn't agree more! Experiments fail all the time, rather than hide failure we should own it, and learn from it! There's nothing worse than the phrase 'my experiment didn't work' - what about it didn't work? What happened instead? What could we do differently?
@ahugumrah In this instance, we ran some tests yesterday afternoon and turns out the gels we made were just too weak. Not as 'gel-like' as we hoped, and therefore they just fell apart overnight in the fridge and dried out. Lesson learnt, now we now what we have to do to improve the system
This is the most recent example of this chemistry-led approach to biomaterial design, from my postdoc. We showed that we could design electroactive materials that could be used to stimulate neuronal cells and change their behaviour https://t.co/IGLxYrVjzL
This was work that was mainly led by an amazing PhD student called Kaja who did a fantastic job bringing together a really interdisciplinary study. We're joint first authors on the paper but she needs to take most of the credit
Key to this was some synthetic chemistry that I developed way back in 2017 for making a series of molecules known as oligoEDOTs. PEDOTS (the polymer equivalent of the molecules I made) are a bit like molecular wires, acting to conduct electricity https://t.co/ZXCI6YaMfn
You could do similar things with metals, that conduct electricity better, but metals are stiff and inflexible - the complete opposite of what we want a material to look like to grow nerve tissue. Conductive polymers partly get around this problem.
Our oligoEDOTs are basically very short polymers, and are even better at overcoming the rubbish mechanical properties of metals. This is with a trade-off of much worse conductivity, but our recent work shows that they are electrically-active ENOUGH to be able to influence cells
The benefit of our system was that we could create really cool architectures at the nanoscale using a technique called melt electrospinning, that basically draws lines of polymers like a printer would. This was a big advance in this work and something we were really proud of
It's not a big jump to imagine using these materials to control the growth of nerve cells in particular orientations, allowing us to start to mimic the bundles of cells that form in your nerves.
Here's another from earlier this year. We got involved in this collaboration when I was in Stockholm with a group who were interested in making cements that could be used to glue biomaterials to tissues, particularly bone https://t.co/mNyFzozUmM
This is a really big problem - we are actually quite good at making materials that help to repair bone, but they can't be used in any part of the body that is subject to mechanical force because the interface between the bone and the material is really weak.
A couple of years back @alinavkirillova reported that adding a modified amino acid, phosphoserine, to a class of materials known as cements helped overcome this problem. Our collaborators (who aren't on twitter) had found the same thing but they didn't really understand why
We realised that we'd need to understand what was happening at the nanoscale interface between the material and tissue, and also at the molecular level. If we could build a load of phosphoserine mimics with subtly different structures we might get some important insight
What started off sounding easy led us down a rabbit hole that resulted in a new synthetic method to make phospho-amino acids, that we then used to make a library of mimics. Using this we could really pinpoint what chemical features were essential for adhesion and which weren't
Turns out having a phosphate group and a carboxylic acid is essential, but the amine is pretty much dispensable. This opens up lots of possibilities to make new additives for bone cements that might improve their mechanical and biological applications
Huge potential for these kinds of materials in treating bone breaks and defects. At the moment one of the most popular treatments is to cut out a chunk of bone from somewhere else in the body and implant it at the site of damage, the use of cements would be a big step up on this!
During my PhD my research focussed on developing new chemistries that could be used to modify proteins with high precision, at just a single amino acid. This is really difficult to do, proteins can be huge molecules composed of hundreds or even thousands of amino acids (1/12)
Modified proteins are hugely important for loads of applications, such as therapeutics (biologics were worth $240 billion last year), for visualising and understanding what is happening inside a cell, or for creating diagnostic devices for detecting disease (2/12)
Single amino acid precision is really important - if you don't have control, when you try and attach something to a protein you will often completely kill its activity and it becomes useless. Specificity and selectivity are key! But they're hard to achieve (3/12)
Making it even more complicated is the fact that these proteins are made up of just 20 amino acids, with an even smaller number of chemical functionalities. How can we selectively modify just one? One common approach is to use unnatural amino acids that are unique (4/12)
These can be installed via a process called codon reassignment - very complicated, but very powerful. We wrote a review on it way back in 2015 that shows some of the diverse structures you can insert into a specific position in a protein (5/12) https://t.co/ytNOGlduYd
Building on work by @ChalkerChem when he was in the group, I got working on trying to target one such unnatural amino acid using palladium catalysed reactions. These reactions have revolutionised chemistry over the last 50 years, but applying them to proteins was new (6/12)
My very first paper back in 2011 showed that we could do one specific palladium-catalysed reaction, a Suzuki reaction, on a protein with high efficiency. This was a big breakthrough for us, as well as a special moment for me personally (7/12) https://t.co/Rox5hyJseJ
Apparently, Suzuki means sea bass in Japanese! Or so I've been told, happy to be corrected by any Japanese speakers out there. Had to talk my boss down from making a sea bass-based journal cover on more than one occasion (8/12) https://t.co/9q5Galh9Cf
Anyway, we then went one step further and showed we could even do Suzuki reactions on the surfaces of living bacteria. This work really set the groundwork for lots of advances in recent years doing metal catalysis inside cells. (9/12) https://t.co/0qN1IMVMDD
An emerging strategy is even using these reactions in animals as a way to 'uncage' drugs, potentially minimising side effects and giving far more potent treatments for diseases like cancer. (10/12)
Another PhD student, Matt, went on to show why these Suzuki reactions were so powerful - he did an amazing job showing that they could be used to really probe the mechanism of a human protein called glycogenin went about storing glucose in the body (11/12) https://t.co/o7SOJqptUa
This enzyme is key to energy storage in humans, and importantly no other chemical strategy was able to probe this mechanism in the same way. A really powerful example of how chemical biology can give us new understanding (12/12)
A final one for today is a review article we published last month and are really pleased with. In it we provide an overview of how we can use light to make cyclic peptides. This important class of molecules have emerged as really promising drug candidates https://t.co/i5dbh4njTa
Cyclic peptides can disrupt the interactions between two proteins in the body - interactions that are implicated in loads of diseases such as cancer, yet were previously thought to be 'undruggable'. By cyclising the peptides they become more more potent and more stable
Making cyclic peptides can be tricky though. Using light to trigger reactions (photochemistry) has emerged over the last decade as a really useful way to achieve cyclisation. With ever increasing numbers of photochemical reactions out there, their use is only going to increase
I'm particularly proud of this paper because it was the first written by members of my group since I started at York. PhD students Laetitia and Nick did a fantastic job writing it, all brilliantly overseen by our then-postdoc James. My input really was minimal
It was written in the depths of lockdown when I was doing a terrible job of balancing child care and work. I was very lucky to have such a great team around me who managed to pull us through a really difficult period with something productive to show for it.
Hopefully it will be the first of many but this review will always have a place in my heart - the memories of trying to have a virtual meeting about figures while also trying to stop my daughter from eating a ladybird are embedded in my brain forever.
@FuhrmannGregor Don't panic there will be mo' pictures of it coming up later this week. I'm looking forward to you sharing yours with the world as well @FuhrmannGregor, I can't possibly imagine that you won't have grown one #showusthemo
First job for today is to review a paper. I've had to remove a few details, hope you don't mind. I'm trying hard to go paper free and getting better at it, but there are some things I still can't do without printouts and this is one of the big ones https://t.co/3BapkfBBn7
Next job will be grant writing. Expect this account to be full of increasing amounts of drivel as the day goes on as I find myself inventing ever more creative ways to procrastinate and avoid writing. https://t.co/cTmucAgLGA
🙌 . Just seen the Nat. Comm. furore - I was thinking what to tweet but I don't think I can put it any better than @thechowlab who I did my postdoc with under our FEMALE advisor. There are many many more who aren't on twitter or who came before or after. https://t.co/a2Zsw3cIO7
I'm officially in the 'going out of mind' phase of grant writing now. Just found myself staring at a squirrel in my garden for a good 5 minutes, wondering how I never noticed all the nuts he's currently digging up from the middle of my lawn. Please send coffee https://t.co/yo538aK8N9
Good news everyone! My grant writing boredom has been ended! Bad news - it's to go get a COVID test and have an 18 month old work buddy for the rest of the week (The COVID test part is the bad part, not the having the buddy part).
The test has come back negative, we're a COVID free household! The testing system has been slated for how long it takes to get results back, but in York we seem to be doing ok, we've had 3 tests over the summer and all were back the next day
Including twice at 5 am - it's nice to know you're clean, but not worth being woken up for.
Reviewing a paper today I was really impressed by the results it presented, until I got to the SI which was really poor - it didn't necessarily affect the results or conclusions of the paper, but it really affected the way I judged the paper and made me overly critical
Made me think about how important this part of a paper is. In some ways the most important, in many journals it's the whole experimental - what the authors actually did and the data that supports their discussion. Yet so often it's left till last and done in a mad rush
I'm always shocked by papers that have 2-3 page SI for a 10 page paper - how can the details that support that work be so scant? And so often it's just a couple of hastily thrown together graphs and no explanations, its pretty much meaningless.
My other major pet peeve is experimentals that just say 'we did it like these other people did'. I don't want to have to follow a literature trail (that can often go back 6 or 7 papers) just to find out how you did a simple experimental.
It would take the authors 5 minutes to just write it down, or me an hour to go searching for it. Why would you not want to make a reader of your papers experience as pleasant and easy as possible, so that people could reproduce your work and cite you?
Maybe I'm missing something and would be interested to hear people's thoughts. For me a robust, long, and detailed SI is always a good thing. If it's well organised and easier to follow, all the better. It will certainly make me feel a lot more positive when I review your paper!
While I always try hard to not let my instincts affect my opinion/review, no matter how much you try to be objective we're all human and it is inevitable that it will cloud judgement. I don't get why you wouldn't put in that extra days effort to stop that affecting your paper!
@NotHF Exactly! But it is nearly a Friday evening so rather than disappearing on a rant I'm going to take a deep breath, get a beer, and find myself a nice 200 page SI to make me happy again (there is such a thing as a too long SI!)
I postdoc'd in a really big, really interdisciplinary group with people as diverse as surgeons and physicists. This environment was amazing for broadening horizons and there are so many relationships that I will carry forward into really useful collaborations in the future (1/6)
I was particularly lucky to share the 'treehouse' office with an amazing group of other postdocs who remain close friends: @thechowlab @ronachandrawati @CampagnoloLab @DrNanoAnne and quite a few others not on twitter. (2/6)
Then there are loads more people from the group who I also became close to, @pashucklab @TheThomasLab @theSeriousLab @AlbroLab @DrTinyTaps @FuhrmannGregor @PuetzerLab and I'm sure many many other's I've forgotten. They are all amazing and well worth a follow (3/6)
But the main point I want to make is how important I've realised the relationships I made as a young scientist are as I move forward . At the time, they were amazing friends - now they're still great friends, but they're also a ready made network of collaborators (4/6)
I know if I need an expert in a particular area I can pick up the phone to one of these people and they'll drop everything to help me, and I can have an honest conversation without the pretence of trying to look like I know what I'm doing (5/6)
I didn't realise any of this at the time, they were just people I enjoyed spending time down the pub with - but I'm now very grateful I met them all for more than just that reason! So shoutout to all the Stevens group alumni out there, I miss you all (6/6)
@FuhrmannGregor I'm sure you're as intrigued as I am about whether Roots good knock in the warm up will translate to the one-dayers?
My week in charge of this account is sadly nearly at an end - I've had a great time sharing a little about my life as a scientist and I hope you all have too, if you've enjoyed what you've read over the last 7 days then give me a follow @spicerlab for more of the same!
Thank you to the @RealSci_Nano team for the invitation and help, I'm looking forward to seeing who will be taking over the reigns tomorrow morning for another fun week of nano/materials science.
@GentlemanLab Once a treehouser, always a treehouser.
[admin] Thank you Chris for an amazing week of science, do give @spicerlab a follow! Podcasts ft. Chris where he speaks about his science are here #91 https://t.co/fxraCjhPJN #92 https://t.co/ZztOxHcPDe https://t.co/jOLbsKDENH
Jo Sharp
[admin] "Electrons can take you Anywhere" Please welcome @JoFeanelwa and listen to the podcast to know what is coming your way this week - https://t.co/1R942wpyTV
Helloooo and welcome to my @RealSci_Nano week! Let's get this Monday morning toast and marmalade party started. I'm Jo Sharp and the plan looks like this: Monday: me and the cool projects I've helped in Tuesday: electron microscopy Wednesday: superalloys and friends...
Thursday: additive manufacturing Friday: dyspraxiaaaaaargh and doing science with it Le Weekend: whatever I do at the weekend - hopefully a bit of kayaking, maybe making some chutney, and I will excuse you from the loafing about parts.
Sooo potted history of moi: Grew up in Thames Valley zzzz Cambridge: undergrad then somehow also PhD whoa Moved to Sheffield to work for spinoff company Got fired, went kayaking Got postdoc job at University of Sheffield doing TEM of ceramics Hung around 10 years
As a student from a state school, but a selective one (at the time, in the 1990s), what was it like at Cambridge? DIFFICULT. Mostly because Natural Sciences is a very demanding course and it's meant to be difficult. But particularly maths-wise...
I had an AS level in maths. Everybody else had at least an A level, mostly one in Further Maths (exactly what it says on the tin) and some, mostly private school students, also had STEP qualifications (Yet More Maths I guess). So I had a lot of catching up to do.
I spent the first year feeling like an impostor & failure, and realise now, we were doing maths that the other students had seen before at school. In second year, everything was new to everybody, and suddenly they were just as stuck.
So I guess, for any teenager considering Cambridge Natural Sciences, I would advise: learn as much maths as you can get your hands on. Doesn't matter if you don't get it perfectly first time, but get to know its face so it doesn't jump out at you.
And remember that you can learn stuff as you go along. I still look up things whenever I do maths now. You don't have to be an "innate maths genius"; you have to be persistent and approach it in different ways & ask people for help when stuck. You can do it.
What else was it like at Cambridge? I met a lot of mean posh people, it's true. Some students, some older. But also some lovely people. (Shout out to my best mates Liz & Laura) And some LIBRARIES oh my gosh. It was nerd heaven, for nerds with a big jumper and 2 pairs of socks.
The best thing was the sheer passion of some of the lecturers for their subject and their research. It was like being shown around a magic forest. When it was good, it was very very good.
But when it was bad, it was... scornful. Muttering into the blackboard. Reading out pages of equations like they were a shopping list and not the very stuff of the universe. Talking at the other end of a loud bright room too fast for me to make notes or understand.
Am I glad I went? Yes. Would I have been glad to be at a non-Oxbridge university? Also yes. I had to do science or I would lose my mind. I gather things have improved since 2002 (would be amazed if nothing did!) but there were things to fix back then.
The best thing about Natural Sciences at Cambridge: it introduced me to MATERIALS SCIENCE which rapidly became my chosen field. I can hold things in my hand and know what they're like right down to the atoms. Can't beat that.
When I was 12 I learned about atoms and I have been looking at things ever since going "WOWWWWW". In Materials Science I can do that every day. It's like an adventure that always has more to give.
After undergrad, I did a PhD. Why? Lots of reasons, many probably "the wrong reason" but here goes. 1) I did my masters project and showed you could do tomography of dislocations in the transmission electron microscope (what?!! More later) and wanted to do more
2) I found out from all the degree bits that I really REALLY like research. So I wanted to do more research and here was an opportunity to do more research so I pressed the "yes please" button.
3) There was A MYSTERY TO SOLVE (how come the tomography worked? What else would work? etc.) "Clues were left behind that suggested a mystery. And to many humans, a mystery is irresistible. It must be solved" - Jean-Luc Picard
4) (and this is not fair and I'm sorry) I had a supervisor and a project lined up already and as long as I got the grades I would be able to afford to live for the next 3 years so...I did. Because I had been extremely broke and I was scared of being broker.
@JoFeanelwa Oh there we go, I fell out of Realsci by mousing over something and not noticing. Faillll. Sorry about that. 4/10 must try harder.
What was my PhD like? Lonely, because I was the only person in the group, in the WORLD at the time, doing my subject. There weren't other dislocation tomography people. So also, kind of uncertain and scary.
At the start, very scary, because I thought everybody in my group thought I was stupid and I just hid and read things. But I realised just because they knew stuff didn't mean they thought I suck, I was like a science beginner. So I got less scared.
I learned a LOT. How to do TEM. How to do the wrong thing on a TEM and get told off. How to code in different languages. Image simulation. All about tomography algorithms. Linux!
I learned that when you write something, there will always be somebody who would write it another way, and you have to figure out which bits of feedback are "you actually need to change this" and which are "this is not my writing style and it scares me".
My supervisor (Paul Midgley, spin bowler of terror) prefers a formal style and thought mine was too chatty; my PhD examiners seemed to like it. So, it turns out, do undergraduates, because it's relatable and clear. There are merits to both, it's like personality.
I learned all the writing tips that are on the pinned post on my own Twitter account and are still the only way I can ever write anything! Which is here. https://t.co/GRaxSInSlk
I learned when you go to a conference, even though you/your funder already paid for the food, STOP BEFORE YOU'RE FULL. I mean eat enough, but don't then keep going until you are sleepy and a bit nauseous. You need to be able to listen.
But the most important thing I learned is that the most important quality in a PhD student is persistence. Stubbornly putting one foot in front of the other even when it's metaphorically raining, snowing, windy, etc. - never. Ever. Quit.
Unless you realise that actually you don't want a PhD, or you are being bullied to the point of illness by your supervisor and they will never change. In that case, run like hell. To another supervisor, or another topic, or another career. It's not worth your actual life.
@fshbf2 Oh I got a bad grade in first year maths, while people around me were complaining that it was boring and they'd done it at school! In second year I chose *thinks* Physical Chemistry, Mineral Science and Materials Science.
So when I had spent 4 years on my PhD and was writing up I ran out of ££ - or ran out of funding, THEN got near enough to the bottom of my savings to be worried. So I applied for a job with a small uni spin-out from the University of Sheffield and got it. So bye bye South!
But it quickly became obvious, the job needed a qualified electron microscopy engineer probably recruited from industry and a lot more expensive than me. So I got fired😭
I had built my savings back up (that was lucky) so I had money to live on, so I went back to thesis writing and then started applying for postdocs. Also I tried kayaking as an adult who can afford a reasonable amount of kit, and it was great.
What was it like working for a university spinoff? They're all different I guess. But for that project, it needed somebody with very specific connections and skills who was probably 20 years more experienced than me, so mostly I felt inadequate and kind of crap
So anwyay, while writing, I was applying for jobs. Then passed and graduated & kept applying for jobs, for 6 months. I got fired in April, & got interviews all summer, then 3 job offers at once in November!
I had one in Trondheim with a lovely group in a lovely place but no microscope yet, so would have needed a LOT of travel. One at Imperial College London for a year, also with a lovely group, but I felt like I'd probably screw it up if I only had a year to prove myself.
That was probably my severely knocked confidence talking, but it might have had a point underneath. The job I accepted was in Sheffield with Mark Rainforth and Tony West, analysing samples of electroceramics for 3 years & no moving house (YES!)
@AtaradSardar It depends so much on your field. I would say if you're in that situation, it's always worth quietly finding out how possible it would be rather than resigning yourself to being bullied.
Next up: how did I get a postdoc? Because it's hard. I kept applying and applying. Every unsuccessful application is a practice run at writing statements and doing interviews if you get that far.
To write an application statement for a postdoc: go through the job specification/person specification thingo they link to in the ad. Copy & paste the points into a Word or whatever document. Then write underneath each point, how you meet it - or, how you would learn it.
I found it easiest to write completely overhyped hubris in the very first draft, then go through and edit it to sound reasonable. "Electron microscopy skills" "I am the best microscopist in the world EVARRRR" - once you set the bar "too high" it's easier to edit down than edit up
Sort of like haggling a price with your own embarrassment - start by stating a ridiculous amount and then you will end up somewhere reasonable in the middle. (Incidentally I suck at actual market haggling.)
You don't have to then turn it into prose - bullet points is quite possibly how the recruiting prof wants to think about it in their head anyway, so you may as well leave it like that as long as it's coherent.
Interview tips: if you don't know something, don't lie or bullshit (pardon my language). Say you don't know. Say how you would find out. It's easy to spot a bullshitter. And a prof usually wants somebody who will be honest about progress, not lie and then mess up the plan.
Have a lot of tea/coffee/cake/whatever makes you awake and happy in the morning. DO NOT go to an interview without breakfast. I did this once and looked like a total plonker until 10am when I woke up.
Most importantly: show your enthusiasm, about their project, about your previous projects, about your PhD, about science in general. Interviewing is boring. Running a project is often depressing. Be somebody who wakes them up and makes them feel happy and optimistic again.
This advice isn't a foolproof guide for how to get a job, it's just little bits I picked up.
@AtaradSardar I hope it works out for you!
@sarah2408 Aww, I'm glad it was helpful!
I ought to point out - I was lucky in that I'd been able to build up enough savings to stick at it for that long. Anybody who couldn't, they are just as good a person and a scientist and they haven't failed at life. 💜
The first postdoc I did was in electroceramics. My favourite project from then was on LiCoMnO4 spinel/rock-salt phase transforming battery cathode materials with @AcadeNik, which was great fun with all sorts of techniques coming together to investigate the material.
I also did some work with barium titanate to find an effect with light element doping; I know exactly what I would do now, annular bright field STEM (Jo Etheridge & team, Monash) but then it hadn't percolated through to Sheffield (poop).
@fshbf2 Oh boy, ask me about this in person or over Google Meet sometime. I have VIEWS.
After doing some ceramics, I then deviated into alloys, mostly because Mark Rainforth had a lot of students who needed some TEM doing and I was quite useful. So I got introduced to a lot of fun alloy systems.
Some steels of various persuasions, mostly looking at precipitates and finding out what they were. Also some Mg with the illustrious @gdk199 (now overtaking me with a Future Leaders Fellowship!), some Cu and all sorts.
Then through unforeseen events I got parachuted into doing a lot of work with Rolls Royce and their additive manufacturing/repair dept, which was a whole different kind of fun.
Aeroengine companies are quite interested in additive manufacturing, both for making parts and safely repairing parts that have got a worn bit. So I got to meet a lot of cool people and cool alloys. Most of that is secret so I am going to do some general alloys stuff Weds.
At this point I also got to cover Mark's second year metal microstructures lectures for a couple of years (shout out to my old MAT2320 students who are now off doing all sorts of fun stuff) which was great fun. I forget how much I love teaching then I teach again and remember.
Ok last thread of Monday: after landing in Rolls Royce land by accident, I went a bit further into additive manufacturing (AM) and started working with @mapphub and @ProfIainTodd to help with more fundamental investigations into what happens in AM.
So far I've only done things with metals - or analysed samples other people made by zapping metal powders with lasers or electrons. I do the microscoping. They do the zapping and building. Additive manufacturing is the topic for Thursday. It's going to be a busy week!
And now...I'm going to make some stew and dumplings because it is coooooold. See you tomorrow Twitter people! 👋🏼
Good morning HU-MANS. Time for more science. Today I'm going to nerd about electron microscopes. Many introductions to electron microscopy say that an electron microscope is like a light microscope but with a shorter wavelength to get better resolution. Well, sorta.
Electrons can act as waves and their wavelength is very short. Look up wavelength limit if interested. BUT. This is like using a Red Arrow performance jet to carry passengers to Germany faster. Like, you CAN. But it can do so much more.
A crystal is like a ceilidh for electrons, all dancing around in arrays that match where the atoms are. When another electron from the microscope comes in REALLY fast, Usain Bolt there has to get through a room of dancers, and join in the dance to get to the other side. https://t.co/phty9Mcokv
It's the outcome of all that dancing that makes it really interesting. The electron comes out of that a changed person. It's a different shaped wave. And some of the electrons hit things in the material and lose energy and you can measure all sorts of things from that.
Walking into the electron microscope room is like putting on 5 different sets of night vision goggles. You can see so many more things. This is why Geordie LaForge is my favourite Star Trek character (narrow margins). He walks around and sees all this with his actual face. https://t.co/l5NQxzXnam
So. Some of the electrons get poinged back out the top of the sample. Some hit the electron clouds of the atoms near the top, and knock out some of those electrons which go flying out the top. Byeeee
How they fly out depends on where there are hills and valleys in the surface so if you count how many come out at each bit of surface, you can map the hills and valleys. That's a secondary electron image.
Some of the electrons get unlucky and manage to almost crash into an actual atomic nucleus. They get sort of slingshotted backout, and from a lot deeper in the sample. Those are called backscattered electrons.
A nucleus with more protons in it has a lot more flinging power. So if there's a blob of something heavy like tungsten hiding in your sample it will glow like a little fairy light. This is VERY useful for a first figure out of what's going on.
These kinds of images are all formed by scanning the electron beam over the top of the sample and recording the intensity of what comes back out the top and sorting it by beam position. So we do these in a machine called a scanning electron microscope.
I just had a look and all my SEM images are of super secret Rolls Royce things 😭if anybody has any awesome non-secret SEM images they would like to share, drop them here! (If nobody wants to, that's ok too)
Wait that's not quite true...here is a (I think) secondary electron image of a cube on a stick that's being sliced and diced by kickass Jack Donoghue in Manchester (more on slicing and dicing later). https://t.co/RCOGmjhEYX
@DrStuartR Beautiful!
We can get even more cool stuff to happen if we - and bear with me here - chop off the bottom of the sample, leaving only 100 nm or even thinner, and make the electrons go a leeetle bit faster, so they can dance all the way through the sample and out the other side.
Then you can stick some more microscope on the bottom to deal with the electrons that have gone all the way through - it's called a transmission electron microscope.
At this point I need to introduce my glamourous assistant Colm O'Regan, experimental officer and champion eater of biscuits, who has been taking photos of microscopes for me, because I'm not allowed in the lab unless I have an actual experiment to do. https://t.co/LANdUczrXe
THIS is a transmission electron microscope. That door in the background is a normal sized door for people to walk through. The sample goes in behind that round blob on the front left. https://t.co/FckSoxAFU5
Front right. Not front left. I have always had problems between left and right.
The sample needs to be riiiight in the middle of that column, so it sits in the right place in the middle of the lenses to make the beam do the right thing. So we make this tiny thin disc 3mm across (more on that later and then we attach it to the end of a stick. https://t.co/jvbLKWmLp2
One such stick is in that clear box near the back of the table. The little cradle at the front is to hold another stick (sample holder) that is in the microscope with a sample attached. Also in the pic: tiny screwdriver for attaching. Loads of tweezers for sample handling!
So what cool stuff comes out the other side of the sample? First up: DIFFRACTION. The electron wave comes out arranged according to the crystal structure in a pattern of spots. The pattern tells us things about the crystal. See also: lots of maths. Here is a diffraction pattern. https://t.co/BvzIAXcB2G
Things like crystal defects, that I was talking about yesterday, also put their imprint in the diffraction pattern. You see those streaks in between the dots? Yeah I have no idea what that is yet. Still got to analyse that data. But it'll be something like that.
When you have a glass lens for light, if you stand sort of halfway between the lens and where the image is in focus and put a screen up, you get a pattern equivalent for this one. (Lasers best. Don't go blind though.)
But for a TEM, you don't put a screen in halfway up the column. Electron lenses are special - you can change their strength. So you can tell the microscope to do some wacky projectory stuff and make the diffraction pattern end up on the screen at the bottom where you look.
Or - this is quite cool - if you blank off all the spots except one of those side spots and then tell the microscope to show you an image from JUST THAT SPOT, you can see crystal defects as little bright lines. Look, here they are! https://t.co/qXi6KEYn5A
This is what it looks like when you sit at the bottom of the microscope and look at the screen. The screen is inside that round hole but in this picture there is a detector for another instrument looking inside so we can't see into the microscope. https://t.co/raMgZwBLy6
The buttons and screens at the side are where you control all the lenses and widgets to make the beam move about and everything. It's like flying a plane except if you mess it up, nobody dies (unless you screw up so badly the centre manager loses it and kills you).
This microscope is my new best buddy the JEOL F200 at Sheffield by the way. https://t.co/YWaaymGwpn not pictured: room full of computers, cupboards, sample holders, boxes and chairs. And it being dark so you can see the screen when you're getting all the widgets set up right.
I'm going to have a little break now, but I will be back at 2ish to talk about how you make something 100 nm thin anyhow, and then some of the other things you can find out in a magic electron microscope.
@beamsontoast Aw man, I never even thought of that. And if you try and stand round the other side to use your left hand you'd be standing in the table. How annoying!
SO as promised, this is how you make a thing less than 100 nm thick. There are two ways, really, and they all involve ending up with a thing 100nm thick stuck to another thing that is 100 microns thick so you can see it and handle it with tweezers.
The first way is by making a little disc and grinding it to 100 microns thick all the way across, then you erode the middle of it somehow until you get a hole, and the bit around the hole is thin enough to let the electrons through.
If it's a nice helpful metal you can squirt it with acid in cold gloopy solvents with an electric potential across it and if you get it right, your sample comes out lovely and smooth with a nice wide thin part. Here is the machine in a fume cupboard. (Thanks Colm) https://t.co/2sOooPmBjE
If it's not a nice helpful metal you can carefully polish the middle down with a tiny little grinding wheel, then you fire a broad beam of ions at it in this machine which works kind of the same. This is good for ceramics and semiconductors and stuff. https://t.co/mXfYoHy3Zb
The other way (and this is my favourite way because it's SO COOL) you can put it in an SEM with an extra bit attached to fire fast ions at things, and you can carve out a little bit, pick it up with a tiny stick, and glue it to a support with a tiny glue nozzle.
This way is also quite cool because you can look for a specific thing on the surface or just below the surface and dig just that bit out and look at that in the TEM. Let me see if I have some pictures of that somewhere...
Aha here is a picture of a little slice of material that's been dug around ready to lift out. The slug thing on top is platinum that you deposit on top to protect the top surface of the actual specimen when you're slicing and dicing round it. https://t.co/1LKeUYa5Xr
The slicey dicey machine is called a FIB - focused ion beam. You can go even faster if you use Xe ions and let them make a bit of plasma (like the sun but less hot) around the surface while you're digging - then you can pull out a massive cube like this (Jack's!) https://t.co/VSDbOCTEbq
That picture is Jack picking up a 100 micron cube with the little pick-up stick, ready to stick it on the support in the picture I showed you yesterday to get cross-sectioned. The big tube is where the Pt comes out to deposit as that protective layer and as glue.
@LunchBobs 👏🏼👏🏼👏🏼👏🏼👏🏼🤦🏼♀️
The last bit of electron microscopy that I haven't talked about yet is spectroscopy. That means you hit things with electrons and electrons or X-rays come out again whose energy depends on what element the electrons hit. It's very helpful for finding stuff...
The electrons in the beam can push an electron from a lower shell into a higher one, like from 1s into 2p or something. That means if you catch the original electron coming out the other side, it's missing that amount of energy.
Well you know how much energy it had to start with because you gave it the energy. So you can do a graph: electrons that came through vs how much energy they lost. And you get a spectrum that's like an autograph book for all the elements in that bit of the specimen.
That's called electron energy loss spectroscopy (EELS). You can also see clever stuff to do with chemical bonds. When atoms form bonds their electron levels move about, and the gaps between them change. And this information is in the EELS spectrum too, if you speak eel.
But there's another half to this story. Your beam electron pushed another electron from a 1s to a 2p orbital or whatever they were. But that electron doesn't want to stay where it fetched up now the bully has gone. So it hops down.
But one cannot simply HOP into another energy level. It has to shed some energy to do that. And that comes out as an X-ray. And just like the EELS electron, that has an energy that is a signature of the element. But this time not the bonding, just the atom. https://t.co/K2gtnnTIrp
That's called Energy Dispersive X-ray Spectroscopy, EDS or EDX depending on how it feels (EDX is what its mum calls it when it's in trouble, EDS is for its mates). EDS and EELS are kind of like those friends that are a bit different but always get each other.
EDS isn't that good with light elements, because their transitions are only little amounts of energy, and the EDS detector can't see them very well. EELS isn't that good with heavy elements, because the EELS signal gets weaker toward the big energies.
So if you use them both, you can find out loads of stuff. EELS on the left, EDS on the right. https://t.co/txUW9PIsX0
Back to the TEM picture: the bit at the top liberates electrons from a little bit of tungsten and flings them down the column through all the lenses and stuff. (This is the R005, an older TEM than the F200, which has extra glasses but is also harder to use.) https://t.co/8BZVyUEIm4
The EDS detector is that big thing on the right (yes the actual right this time) which is a tiny detector and a big tank of liquid nitrogen to keep it cold. That's an old design, new ones don't need the tank, and they are hidden away inside on the F200.
Electrons are not actually green - but when they fall on the screen at the bottom (behind the round hatch there) they hit a screen of phosphor which emits green light to show you where the electrons are, so you can line things up before you record your images and data.
That's me all Twittered for Tuesday. I need tea and cake. See you tomorrow Twitter!
@NotHF Aw, thanks! 😊
[admin] "Electrons can take you Anywhere" Extended conversation with the amazing @JoFeanelwa is out now - https://t.co/uFZiAjpecg
Good morning Twitter people! Today I'm going to talk about alloys and why some of them are super. An alloy is a metal, with a mixture of elements in it. A normal alloy is mostly one metallic element with bits of other elements in.
A recent development is a thing called a "high entropy alloy" - which it turns out was not that high entropy, and has many other names now too - where you have about the same amount of multiple elements.
High entropy alloys haven't proved awesome for anything yet, but people said that about electricity and the telephone, so...it's good to have them around and known about to see what happens. Anyway. That's not my area, I'm rambling.
I'll cover a couple of alloy families that are put in the burny whooshy bit of aeroplane engines - nickel superalloys (they are rather super) and titanium alloys.
I'm going to unashamedly link to Wikipedia here, so that I know I'm not accidentally putting up something confidential from my own pile of diagrams. So. This is a jet engine. https://t.co/w57maRIuov
I'm going to talk first about the spinning blades just after the bit where the burning happens - the last purple ones in that diagram. Those have one very important role that they have to not screw up. They have to spin round really fast in very hot gas and NOT GET LONGER.
If they get longer they scrape the outside of the combustion/hot gas chamber too hard and engine go kablooey. There is a very special class of materials made specially for this, called nickel superalloys. They are very super indeed. https://t.co/auiaMbLqw1
When an alloy is sort of more than halfway to its melting temperature, it wants to get longer if you hang a weight on it, or spin it around very fast. Atoms diffuse along defects in the structure where it's quite loose - grain boundaries and dislocations, mostly.
This is called creep. (It creeps up on you and then crunch.) To make it not creep, we want to not have pathways of dislocations and grain boundaries going from the inside to the outside of the turbine blade, so the atoms can't sneak along them.
We do this with dislocations by tying them up in knots. If you make a certain composition range of Ni alloy, with a lot of Ti and Al, it forms these squarey precipitates called gamma prime γ'. Loads of them. Rafts and rafts of them. More than half the alloy can be precipitate.
A prof called Dierk Raabe made an AMAZING video showing this - it's at the top of this page. The thing at the start is a turbine blade. The blocky things when it's most of the way zoomed in are some of those precipitates. https://t.co/1BlrQ7vb8H
This γ' precipitate is very clever because its structure is ALMOST the same as the Ni around it except some of the atom sites in the crystal structure are systematically occupied by Ti or Al not Ni.
If a dislocation goes through, it unzips the ordering and leaves a bit of really very unhappy material behind where the wrong atoms are next to each other. You can re-zip it by having a second dislocation follow the first one close behind.
So dislocations have to wait for a friend to join them to go through. But the dislocations in the Ni are in those narrow channels between the γ' blocks. It's like trying to find your mum again in the supermarket. So by and large, they are stuck and tangled up in the forest of γ'.
So, there isn't a nice easy dislocation path for atoms to diffuse towards the outside of the turbine blade and make it grow. WIN. But there are still grain boundaries. We can deal with this in two ways: block them up with rubbish, or take them away altogether.
By rubbish I mean carbides of heavy things like maybe Hf, Ta, W, what else...all sorts. There can be like 10 elements in one of these superduperalloys. These make the grain boundaries also not want to move about and line up along the blade, so they're not useful roads for atoms.
They're kind of like if you wanted to run raindrops along string to the ground, but the string is stuck to a board with drawing pins.
That's good enough for the really-quite-hot bits of the engine. For the very-hot-indeed bits, you take the grain boundaries out altogether and grow a turbine blade that is just one big crystal, by growing it with a squiggly bit at the bottom. What?!
Like in this video from the Prof Hongbiao Dong via Prof Sir Harry Bhadeshia https://t.co/aUtLfmkWWa The squiggle goes at the bottom of the blade; you can just see the bottom of the blade on the left. The bit on the right is sort of a supply vat.
Ooh this video is awesome too, look! https://t.co/xzWNQifmhu I've been in that brick building to visit my colleagues in materials research. They have cabinets of old turbine blades and pictures and the way to the toilet was "left by the blades, right after the helicopter".
I have to host a seminar soon, so I will be back this afternoon to ramble on about titanium.
I'm back! So, titanium. (I like it.) Titanium is light and strong at the same time. This is used for the slightly less hot bits of engine, because nickel is heavy. If you made all the turbine blades out of Ni you would use loads of fuel and put unnecessary stress on bits.
A lot of other bits are made of Ti alloys too - landing gear, engine casing, etc. plus all sorts of bits in other industries. So it is a very important and very cool metal.
Titanium on its own, not alloyed, likes to be hexagonal close packed at ordinary sort of temperatures (including in that bit of engine). Once you get to sort of 1200C it changes its mind and wants to be body centred cubic instead. https://t.co/1fgPyhdziD
Hexagonal (hcp, α) is comparatively squishy, it can absorb some stress and move dislocations about and cope - it is tough. BCC (β) is comparatively stiff and strong. If you get both of them together, you get the toughness from α and the strength of β. TEAMWORK
You get this by putting other stuff in the Ti to make an alloy. For example something like Mo will make β happily stick around down to room temperature, and other elements will also make α be there too, so you get this nice strong tough both-together structure.
If you get the heat treatments right you can also grow some big lumps of α to absorb energy & make it tough, then some middle sized ones, then some little ones with a good network of β between them for strength. Here is the sort of thing I mean https://t.co/wIQwDa3Hh6
That's a backscattered image from an SEM - the β shows up bright because it has nice heavy Mo in it like I said before. That image is where I accidentally analysed the handle of a different thing (oops).
Because the microstructure is so so clever and particular and depends on heat treatments, it can be quite challenging to additive manufacture things out of Ti - I will talk more about this tomorrow!
So as a last bit for Wednesday - what do I do with these alloys? I get given bits that have been additive manufactured or processed by some other cool new method, and I find out what's inside.
I might be looking for particular features, or I might be finding out what the microstructure is like (and how it changes across the sample, sometimes). I will usually do some optical microscopy and make a plan first, because electron microscopes are expensive to use.
Then I will decide what length scale I need to look on and what analysis techniques I need to use, and make a Cunning Plan, usually involving FIB slicing and dicing somehow, to get the information we need. Then...I do it!
(There's usually an intermediate step of figuring out how much ££ it will cost, in microscope time and Jo time, and squeezing that through the Finance machine so I'm allowed to do the work...)
Once I have data, I have to sit and process it to find out what it says, and most importantly put it in a way that the sample's owner will undertand - especially important when it's a company and you might be talking to people who are not materials scientists by background.
Soooo that's me done for Wednesday. Tomorrow I will be writing about additive manufacturing, in between madly writing a thingo to try and get some ££ for a project about additive manufacturing, in some kind of supreme irony. Have a nice evening everybody!
Wowww I overslept. Today my plan is to tweet about additive manufacturing. Morning everybody.
Ok so what's additive manufacturing? Making things bit by bit instead of all in one blob. Kind of like lego or knitting. You can do this with loads of different materials but in very different ways. It's called "3D printing" but that's only one bit of it.
3D printers that you can buy, use polymer in strings that is heated up to sort of melty temperature so it will stick together and you can build little plastic thingos from a hot print head that moves about in layers. That's nice and easy except when it gets lost and prints a mess
That's a very specific set of polymers - you can also do things with UV curing and all sorts. Polymers aren't really my field - @CandiceMajewski knows looooads about this.
You can also print ceramics in an organic sort of gloop, then burn away the gloop and you are left with a nice ceramic structure. There are all sorts of possibilities along the way. Look for...Iuliia Elizarovna and friends at Imperial College London, for example.
Metals are the bit of additive manufacturing that I'm involved with. They usually involve metal powder, a great big laser and a lot of pew pew pew, and I will talk more about that after lunch.
Most of my additive manufacturing work is with the MAPP consortium (Manufacturing by Advanced Powder Processing) @mapphub which involves Sheffield, Leeds, Manchester, Oxford, Diamond X-ray source, Imperial, UCL and...have I missed anybody? I hope not.
We work together on all sorts of additive manufacturing and general powder-related stuff, and do some exciting stuff. I will link to some stuff on MAPP's youtube account later when I talk about metals and pew pew lasers!
Ok metals! When you additive manufacture metals you need two things: 1) Metal 2) Energy 3) In many cases an inert gas atmosphere 4) A LOT of PPE for dealing with all that crazy ass metal powder.
The energy can be in the form of a laser (pew pew pew) or an electron beam (in which case everything happens in a vacuum). The metal can be in the form of powder or a wire like welding.
The powder can be introduced to the pew pew pew in two ways: you lay down a bed of powder and trace the laser/e- across it in the outline of the thing you're building, or you attach hoses to the laser and fire powder into the focus of the laser beam and hope it sticks.
When you've done one layer, you go back to the other end of the thing you're building, move up a bit and add another layer on the top. It sounds like a ridiculous idea but it happens like magic, suddenly there's this thing emerging.
The first one is called Selective Laser Melting or Powder Bed, the second one is Directed Energy Deposition or Blown Powder. Here is an animation from the MAPP Youtube channel about DED! https://t.co/QAdvmt1ICN
And here is a video from a company that make the machines for DED, called BeAM. PEW PEW PEW https://t.co/TKf3cequgK
You see there's a glowy bit at the top? That's mostly metal that's just solidified and is still glowing hot, but right under the beam is a bead of molten metal that's catching the melty bits of powder that have been through the laser, which we call the melt pool.
All sorts of cool stuff goes on in the melt pool. Because most liquid metals have a surface tension that depends strongly on temperature, and there's a massive laser at the top and a big lump of metal underneath, there is crazy fast stirring going on in that melt pool.
Which way the stirring goes and how fast it goes, and the shape and size of the melt pool, and how hot the layer underneath gets when you build the layer on top, and loads more things decide the microstructure of the metal you get.
The size and shape of the grains and which way round the crystal structure is compared to the shape of the part (orientation), and the shape & size of precipitates and little bits of phases in the metal (like α and β in Ti) are all affected by all those things.
The end result is that additive manufacturing of metal (and everything else) is really, REALLY complicated. But it's also really awesome. You can make stuff that you'd never be able to make any other way.
For example (and this isn't secret) many jet engine companies are starting to make bits of engine that have the discs and blades all forged into one lump, not separate blades that come off, so they can extract more power more efficiently from the engine.
When one of the turbine blades gets damaged, for example a bit of grit goes through the engine or a fatigue crack is found in regular inspection, it's silly to replace the entire massive part. It's better to cut off the broken bit and just...regrow a new bit on top.
So GE, Rolls Royce and a few more companies are doing a lot of work into being able to grow back a bit of engine with a little bit of powder, some PEW PEW PEW and some very clever machines.
So how do we untangle all this mess? A lot of approaches. Peter Lee & his group at UCL have a magic setup at the Diamond X-ray source where they can do the PEW PEW PEW in the middle of an X-ray imaging machine and make videos of what happens in the middle of hte melt pool!
You can also systematically vary different parameters and see what the outcome looks like in the final builds, which we do a LOT of at Sheffield. This goes in parallel with a lot of computer modelling, including machine learning, from other partners in MAPP.
Pores turn out to be a pain in the neck for additive manufacturing. Because of all this stirring, bits of gas can get stuck in the melt pool, both from the chamber and from any powder particles that were hollow. And some of them get stuck.
That leaves a pore in the finished build which is not helpful; it concentrates stress and makes it vulnerable for fatigue failure. I, Jack who I mentioned on Tuesday, and a team of other awesome people did a study on pores recently.
You can squish pores away under high-ish temperature, but if you then heat treat the material (like Ti alloys need to be the right microstructure) the pores grow back. We found that they grow back a really funny shape. (My little potatoes!) Paper out soon...
Oh! Talking of fatigue failure - a woman called Constance Tipper founded a lot of that entire field in the 1920s. Just look how awesome she was! https://t.co/z3CiVpcCDQ It is my absolute mission to put this woman in lecture notes one day. She was just great.
And with that, I will declare this the END of Thursday because I have to do some project planning. Tomorrow I will be tweeting about dyspraxia because I've got it like a slightly painful free gift. Right now though I have to calculate things with money. Wah. Byeeeee
@mapphub Awww thanks! 😊
Ok good morning! And quite a late morning because I had a lot of things to clear out of my brain before it had space to think. Today I am tweeting about dyspraxia!
What is dyspraxia? It's a thing where your brain deals with information strangely. This is most obvious in the way it deals with information about where your body is in relation to everything else - inaccurately. It is sometimes called "clumsy child syndrome".
My brother has it worse than me and he literally walks into every new door frame he meets. I got a new bigger fridge what...2 months ago? Yeah, still crashing into that thing.
It's also most obvious in handwriting - fine motor control is difficult so our handwriting is terrible. My brother's is very large and angular and child-like. Mine is more...it's a line with lumps in. Nobody else can read it. Problem is nor can I most of the time.
As an undergrad this was PROBLEMATIC in lectures - doubly so because I didn't know that I had dyspraxia. I came on a fix where I would concentrate ONLY on writing the gist of what I heard, legibly, and go to the library in the afternoon to actually *understand* and rewrite.
This also means that we have to concentrate super hard on tasks like writing and walking. I do canoe slalom. I'm rubbish, I rarely come in the top half of my division. But my brain is working so hard. That's why I had to pick a sport that was great fun, to compensate.
And yes - I was terrible at PE at school - both because of this and because of the other features that I will talk about later today.
Finding small movements difficult makes TEM an...interesting career choice. I can only use one kind of tweezers, the kind that hold themselves closed, so I only need to think about moving and not gripping too. If I lose them, I can do nothing.
I lost my tweezers last year for a few days and I had to ask somebody else to mount my samples for me because I couldn't use tweezers anymore. I actually cried in the lab with frustration.
The physical part makes other things hard. Walking on an uneven surface - this is where I work https://t.co/K1Nel1711N you see the surface in front is all bibbly-bobbly and then goes down a hill? That is SO HARD to co-ordinate my feet on. Luckily there's a side door.
Building sites drive me crazy - suddenly a bit of pavement I at least knew is different and needs ALL my concentration to walk on - usually with cars going past so I need 2 brains, one for the cars, one for the ground.
And buses oh my GOD - walking to a seat, sitting on the seat, getting up from the seat, walking to the front. There are potholes right before my bus stop. Those b****ds have made me hit the bus floor several times. And I look drunk, and people frown. But I'm just different.
Maintaining posture is also tricky - my back bends a bit too much unless I concentrate really hard on it. And the ground. And the cars. And the person talking to me. And and and. It is all hard.
This is why during lockdown I had an *easier* time than normal, and why only now do I have the brain space to career plan and apply for funding and things. Because I'm not always exhausted to the point of collapse from just getting to work and back every day anymore.
I have to go get a flu jab today (woohoo) but after that I will talk about how dyspraxia is different in different people, and the bits people miss until it causes a disaster - verbal processing and sensory processing.
I have been flu jabbed. My arm hurts. Ok back to dyspraxia. Dyspraxia in my case strongly affects verbal processing. When I had the ability tests at Occ'l Health & got diagnosed I did pretty good on everything then when we did the verbal processing test she just...stared.
Apparently I am in the bottom 10th percentile of the population for verbal processing ability and the rest of my brain has been carrying that bit for my whole life. What does this mean in practice?
When I'm talking, it's hard to put the words in the sentence properly. Like, the right words in the right places to say the thing I want to say. The native language in my head is mostly pictures. This makes me quite good at languages, ironically, because I don't go via English.
So when I try to say something, sometimes the other person/people don't understand the sentence, it doesn't make sense. It's easier in text because I can read it back before I press enter. But in person I sometimes have to have a few goes.
It made me very VERY bad at essays at school. Talking on the phone is hard too - I have to write a script to get it right. It's not just output that is affected - verbal input has problems too.
When I read scientific papers, I usually have to use 90% of concentration to understand the syntax of the sentence, and not enough is left to understand the actual meaning. So I have reading journals where I translate the paper into diagrams/brain language and then understand.
Here is some journal - there are words but they're more like...names of things and ideas with symbols for how they relate to each other, than sentences. https://t.co/fozmmYFKCk
(Also this is my bestest writing so that I can read it) Writing is also a problem but...not as much, because I tend to write in very simple constructions, so I more get told it's too informal. Writing papers is like filling in a form where you know what to put where.
Because of the co-ordination thing, I also find food time at conferences difficult. I can stand and eat as long as nobody's watching. I can stand and talk but I tend to get nonsensical fast. Stand + eat + talk is usually a recipe for disaster, if I've been listening all day.
This does mean I get to meet some interesting people though because I started carrying a blanket to sit on the floor when there aren't enough chairs for everybody and it turns out I'm not the only one and often gain some lunch buddies.
Verbal processing's evil twin is: auditory processing disorder. This means I hear EVERYTHING equally. Listening to a seminar and a lorry drives past outside? Bye bye speaker's sentence. And when there are lot of people talking, I hear all of them and understand none.
(People who bring rustly food into seminars and eat it there have a special place in hell and that place is LOUD and ANNOYING)
In person, lip reading helps enormously. It's like a verification dataset for the stream of noise and its 50% accurate brain interpretation. On recorded media, captions are excellent. I rely on subtitles for Midsomer Murders exactly as much as for Wallander.
Remote meetings have been...interesting, for this. Ideally you can listen to the person talk and watch their lips and it's almost the same.
But in a big meeting people turn their cameras off to save bandwidth so they can hear. That means my brain is suddenly using all its effort to interpret the audio input because the lipreading has gone.
If I do that for an hour, I'm knackered until the next day. If I do that for four hours, the rest of the week is gone. And by knackered I mean, can't operate a bottle top or a teaspoon without 3 goes. It's ALL connected.
Not every conferencing platform is created equal. U. of Sheffield use Blackboard, which is adequate for a small number of people but for a big number something weird happens to the sound. Like some of the Fourier components get fluffy somehow. And parsing is even harder.
I'm told Zoom captions are usually adequate. But Blackboard captions are jellyfish cushion procrastination knife fork spoon brushing. I mean, so inaccurate as to be basically useless.
I found out last time I did a long Blackboard meeting that it's easier if I lie on the floor in a ball on a yoga mat with my eyes closed. Something to do with not needing to concentrate on posture or vision, I guess. Mmm, professional.
So the Year of the Plague has been...interesting. Also a thing, coupling with auditory processing: sensory overload. I am usually operating at 90% brain load just to not get run down by a car or talk semi-coherently. So it doesn't take much to make by brain struggle.
Loud room full of jostling people? Loud noises? Fireworks? A really strong smell? Bright fluorescent lights? Bye bye ability to do things. (People who wear loads of cologne to microscope sessions can Just Stop It.) I turn out the lights in the FIB room to do a hard lift-out.
Now a thread about late diagnosis. I didn't find out I have dyspraxia until a few years ago...34 maybe? 35? I had just gone through school accepting that PE teachers and English teachers thought I was lazy, stupid and/or and a bad person.
It didn't occur to me that there was some problem in the disparity of their opinion compared to science and maths. As a child you just...assimilate it into your idea of how the world goes. Some teachers hate me. Ok then. Maybe I suck.
In the 80s and 90s, my brother was diagnosed with dyspraxia because he really, really had problems writing. Mine is less severe and I think it was easier then to write off a little girl as messy, a bit dozy, not really with it.
As a teenager I think I got sorted into "the technical type" so I was expected to be bad at English, History, home ec, art, etc. and it was seen as evidence that the model of the world as having two types of people is correct, rather than symptoms of a possible problem.
As an undergrad, I struggled enormously, with getting to practicals, doing practicals, HEARING in practicals, understanding lectures, almost everything. I thought, ok, finally the world is seeing that I do in fact suck, this is what I expected really.
But in the second and third years I started noticing what was easier and having the...confidence? No. Cheek? Maybe. To decide to do things a different way to how I was told to. Like scribbling the lecture notes in the morning then going to the library in the afternoon.
I found out, when there was practical work that involved figuring out how a material worked rather than following instructions from a long way away in a bright room, I was getting really good marks. So I worked my ass off on those, knowing my exams would suck.
My PhD was... honestly I liked it. I still didn't twig that things weren't this mismatched for other people. And my supervisor saying that reading wasn't work, didn't help at all. But I figured out ways through and somehow did it.
I only thought about a SpLD a few years ago when I went to a session on how to support students with SpLDs and they got to dyspraxia and I thought...waaaait...that's me. Then they said it runs in families and I went awwww shit, will you look at that.
So I got in touch with the Disability & Dyslexia Support Service and had some tests done of various dimensions of cognitive ability and it came out, yes, I have dyspraxia. And suddenly a lot of things made sense - and most things in my life were not in face because I suck.
So for anybody else out there who is really good at some things but every now and again you wonder why you are so stupid in very specific ways the "spiky profile" description - if you can, investigate. You never know.
So - last proper thread of the week. There may be some snaps of the weekend if I do anything fun. What has dyspraxia taught me as a scientist?
It has made me be resourceful and courageous. If one way to do something isn't working, I know now to stop doing it that way and find another way that does work. Energy is precious. Other people's whining about appropriateness is infinite. Find a way that works.
It has made me need to be patient - especially talking to people, when they don't understand and I don't understand and I need to have a few tries.
It has made me STUBBORN. To be fair I think some of that might be genetic. I will. Not. Quit. Nope. If I have to crawl in a blizzard I will get that thing done. Because usually, I do end up doing the equivalent.
And it has made me understand deep down how things work. I couldn't get how to drive a car until I understood how the engine and the gears worked. I couldn't get how to use a sewing machine until I took the side off and watched it. And doing science, is ALL that.
Annnd that's me for Friday. Me and this cat who WILL NOT GET OFF ME. I have some blind stumbling in the darkness of research funding rules to do now. It's been lovely and see you from the end of a camera at the weekend! https://t.co/4V8rXZKHi7
@Loberd3 Glassware is generally safe because I am Really Careful and concentrate hard. TEM samples the same. It's mugs, lamps and taps that get me. The number of times I've stubbed my toe on the goddamn table making a cup of tea.
And the last bit of the week is... The weekend! Here is what I did (none of it work) : Finished making hamster shelves so partner plus pets can move in in 2 weeks (engineering) Made chutney (chemistry) Moved books etc Cat helped https://t.co/rXaSnh7dl6
And with that, I finish my week as @RealSci_Nano! I had great fun, I hope you did too! Bye bye 👋💜
[admin] Thank you @@jofeanelwa for a wonderful week of science. 🎊 Do give her a follow. Listen to the podcasts to know more about Jo's research. #93 https://t.co/1R942wpyTV #94 https://t.co/uFZiAjpecg https://t.co/XTVfVhKG6j
Sherif Abbas
[admin] "Make Materials Modelling Great Again" Please welcome @Sherif_A_Tawfik and listen to the podcast to know what is coming your way this week - https://t.co/qT3RbREUxR
def sherif(): print('Hello world') print('Do you like python?') if __name__ == "__main__": sherif()
You've heard "modelling" a lot during COVID press conferences. Modelling using good tools can make a big difference in COVID, materials, batteries, fusion, climate change, etc. I am a materials modeller who's concerned about making modelling accurate, sensible and efficient
My primary research interest is: unravelling colourful the wonders of material defects. For example, in this paper, certain defects in very thin sheets of boron nitride can emit tiny packets of light, the sort that can be used in a quantum computer! https://t.co/GSdAtL3EDl
Last year I wrote this bit of sci-comm to explain electricity to.. 5 year old kids :) https://t.co/MvsoAUoYsF
Isn't it cool that Google suggests #python right next to #DFT? I just hope that Google is thinking this is "density functional theory" not "discrete Fournier transform" Well I am sure Google thinks it is "discrete Fournier transform" 🙃 @sherif_a_tawfik https://t.co/47Mkm6Wo9s
@CaboAntonija @Sherif_A_Tawfik Thanks Antonija :)
As a material scientist, my small-talks usually be like: A: "What do you do?" Me: "Computational material science. I use computers to discover interesting materials for applications such as optics, 3D printing, batteries and .." A: "So what do you do?" Me: "I build LEGO cars"
Will be doing a bunch of #compchem #scicomm this week. Let's start: #DFT sucks but..
@MoatazAttallah I've been working on a computational project to find new liquid metal alloys as ink materials - still in preparation
@MoatazAttallah We gotta chat about that stuff at some point man :)
Defects are pretty awesome: I collaborated with @Dr_TaimurAhmed and @SumeetWalia4 to explain this using #DFT #compchem in their masterpiece on artificial synapse with black phosphorus. These guys are building artificial brains one neuron at a time. Kinda like in the movies 📽️😱 https://t.co/KZG2P7qbUS
@olexandr @CompChemBioBot Yea, GW/BSE. But for large systems, with a bit of compromise and parametrisation (+maybe ML): orbital free DFT. Very large systems: eFF on LAMMPS?
@olexandr @CompChemBioBot And we've got to inject ML into DFT, like the AIM stuff you're doing https://t.co/QT4VUiO23C I believe that's more promising than the empiricism in PBE/LDA/HSE/vdWDF/...
I am planning to do #Python @Skype tutorials this week. Which topic would you like me to start with?
With the help of @DaleAOsborne, I produced this image to describe my work in https://t.co/ge1qJVleFg: understanding anelasticity of nanowires using quantum mechanics. "Anelasticity" is when you bend something and then it doesn't restore its shape right away after you leave it. https://t.co/cvrZ4uoSoV
Further on small-talk. Me and my wife @MageedDina introducing ourselves to people: Me: "I do computational material science" Dina: "In my PhD I study how major events such as Christchurch attack has shaped the Australian media" And then she gets ALL the attention 😂🙆♂️🤓
@MaterialsDan @DaleAOsborne Plasticity: ability of a material to be deform Elasticity: the tendency of a material to restore its original shape immediately after removing load Anelasticity: the tendency of a material to restore its original shape, but with a time lag, after removing load
For #DFT peeps: DFT doesn't quite understand van der Waals (vdW) forces in 2D materials. It has to be complemented with "corrections". This work with vdW GURU Tim @timgould_scienc shows that there are great corrections out there, not only SCAN-rVV10 https://t.co/taINdkL7M8
@KelseyInTheLab @Skype In a few hours I will share registration info - it will obviously be free :)
How to use #python to access structure databases? This 1 hour tutorial teaches the basic of using python to access the #MaterialsProject. https://t.co/k5QLQ7TREB
Guess what? You can do little bit of DFT on your PC using #python. #GPAW is a python-based #DFT software that is easy to learn and very easy to setup. This tutorial teaches you the basics of using GPAW. I hope you find it useful! https://t.co/n7mETXcCim
@sherif_a_tawfik
@Sherif_A_Tawfik
OK that's only getting harder now 🙃 Seems like both general python and python for mat-sci. Will wait for a few more hours :)
Spotted a cool computational materials #compchem bit in an experiment paper and got some questions? Please share the paper's link and ask, I'd be happy to answer your questions!
I am an Egyptian-Australian 🇪🇬🇦🇺 (صباح الفل - g'day), arrived Sydney in 2013 to pursue a PhD in physics with the wonderful Prof Catherine Stampfl. Then started my postdoc journey at @UTSEngage, then @RMIT. Academia in Oz is truly inspiring - and challenging! @Sherif_A_Tawfik
@TRunyararo @Skype @LinkedIn We can have multiple sources :)
@EllaBellaBleu Will tweet details about the session shortly :)
@TRunyararo @Skype @LinkedIn Commercially, I mainly teach python on @coursera - will share info shortly
I am passionate about teaching. I teach chemistry and physics at uni, and python at @Coursera. Been lucky to have 800 learners on Coursera for my 3 courses so far. https://t.co/urXoJnKifq
@CaboAntonija @coursera Coursera has this page for applying to be a teacher of short courses (guided projects): https://t.co/LgI3UfhVuZ
OK, let's start with a tutorial on general python. Will tweet that now.
Hi everyone, wanna learn #python? I will be conducting a 1-hour online tutorial over @Skype on Thursday 3rd December 2020 (GMT+11 Melbourne time) to teach the basics of python for analysis of numbers and text - please register here >> https://t.co/0Iyh6LvvJ6
@sherif_a_tawfik
@KelseyInTheLab @Skype https://t.co/b5pCYp3hU3
@EllaBellaBleu Here you go: https://t.co/b5pCYp3hU3
@sanarribas @DaleAOsborne Maya :)
@realscientists Thanks for sharing Tiara :)
@NanoIn3D @Sherif_A_Tawfik Thanks Peter :)
@_souringpie @Sherif_A_Tawfik No, just a google account because we will use Google Colab
[admin] "Make Materials Modelling Great Again" The extended conversation with @Sherif_A_Tawfik is out now! https://t.co/tERH5ERBZK
@danbri @realscientists @Sherif_A_Tawfik Now that he is out, one can reclaim that phrase 😀
@danbri @realscientists @Sherif_A_Tawfik But i agree - it sucks being reminded of that loser
Experimentalists, I've got a question for you. If you're adding a #DFT bit into your paper, what's the reason?
#DFT peeps: if you're choosing a DFT software, what's the first thing you will look for?
Physicists: I've been having trouble finding *any* reference that *validates* the Biot-Savart law for a wire whose cross-section is neither square nor a circle. I looked so hard for evidence, but nothing. I expressed my doubts in this paper: https://t.co/car6WPbSbO
Happy to be wrong, but where's the evidence? Textbooks and experiments at nano/micro/macroscales in scientific/IEEE journals that calculates such B field, are mostly for cylindrical wires. Non-cylindrical? Just a FEM calculation, no comparison against experimental measurements..
Thinking of an electromagnetism which misses Maxwell-Ampere's law could be a fun exercise. And might hold some truth about fields that was hidden by the breathtaking beauty of Maxwell's maths @skdh
Experimentalists, another question for you. You start a collaboration with a top-notch theoretician to explain a measurement you have. Their predictions contradict with your data. What would you do?
@semontis I do agree
@CandiceMajewski True! But I am limited to 4 options am afraid
@AndrewR_Physics I'd like to read that paper 🙃
Your most inspiring paper? Mine is this. No single experiment or calculation. Only interpretation. But analysed and expressed so elegantly it landed in a Nature. https://t.co/zs94Qo2uLZ
@KaMeLPullin @Sherif_A_Tawfik It's the glorious "density functional theory" that's used by some material scientists to analyse reactions, surface phenomena, optical phenomena, and many other things
@mclaurenseries Certainly, the model might need "re-parametrization"
@mclaurenseries But also, maybe the experimentalist needs re-think the hypothesis, such as: is the material in question A, or maybe it's B? Or something else? Is it ok to assume we can neglect the solvent surrounding the reaction? etc.
@AndrewR_Physics True, even theoretical models, such as Hubbard's, are both too numerous and idealistic yet they fail to please many experimentalists - I once spotted a review paper in the field advising (jokingly) to ignore theoreticians - will try to find that paper in my labyrinthical folders
@ZoeSchnepp @CandiceMajewski If only the editors of high IF journals could find that appealing .. ☹️
And this paper is an experiment on nanowires which suggests there could be a contradiction between measurements and Biot-Savart equation! https://t.co/MOfFHGgEbS
@mclaurenseries True!
https://t.co/dFblFtgOIK
Now snapshots of my work. I like creating twisted bilayer 2D materials, such as this one: #silicene over #graphene with a twist angle. #twistronics https://t.co/l28t8seswS
I use #machinelearning to basically *avoid* doing DFT, because DFT is expensive to run sometimes. Here, I used machine learning to predict thermal properties of materials. ML proved to be pretty accurate! Happy to elaborate more https://t.co/AG6S8lkH92
@ZoeSchnepp The second is to be open with regards to choice of model. For example, DFT doesn't work, try molecular dynamics. Still no, try classical models, etc.
So, what's DFT anyway? It's a smart idea to reduce the complexity of quantum mechanics. Quantum mechanics can be super complex, even for a single atom. DFT can let you do quantum mechanics for hundreds, or even thousands of atoms. DFT is so smart it got a Nobel prize. 1/n
What's meant by "do quantum mechanics"? I mean learn the properties of something. Formally speaking, it means solving the Schrodinger equation, one of the toughest equations in physics 2/n
and when you solve the Schrodinger equation, you learn the properties of your atom via the properties of its electrons. When there are so many electrons in the atom, it becomes pretty hard to solve its Schrodinger equation 3/n
And that's where the coolness of DFT emerges: just don't bother about the electrons individually. Instead, deal with electrons as a "sea of charges". This reduced the complexity of quantum mechanics tremendously but at the expense of accuracy 4/n
And here's why different papers would get different results for the same material using DFT: DFT is an approximation, and there are many flavors of DFT, each claiming to be a better approximation. So either the two papers used different flavors, or one/both papers suck(s). 5/n
New DFT student wonders: which flavor to start with? Crystal systems? PBE is a good starting point, and then u can add sub-flavors to it. Molecules? There's a war going on now on this - if I suggest #B3LYP (traditional choice) I'll hear shots being fired 😱 but its not bad. 6/n
A reminder - by the way it will be on @zoom_us because @Skype crashes my Mac when I share my screen :/ https://t.co/b5pCYp3hU3
Scientists doing theory work, like me: in my humble POV, it's always better for us to stay in touch with some sort of lab work, even as a hobby. Sometimes when we do theory too much we lose touch with the real world, and might end up with elegant theory that's totally irrelevant.
@goldclusters Ah in the second line you surrounded the collection with parentheses, "(" and ")", which means you created a tuple. In the colab, there are square brackets instead, "[", "]".
Hi all, this tweet sees Sherif ending his curation of this twitter account. Been fun sharing my work with you'll!
@BatteryBulletin Sounds like a plan :)
[admin] Thank you Sherif for a wonderful week of science and a perspective from theory world. Do give @Sherif_A_Tawfik a follow! Podcasts ft. Sherif where he speaks about his science are here #95 https://t.co/qT3RbREUxR #96 https://t.co/tERH5ERBZK https://t.co/RLzyhPb0MF
Jarriaun Streets
[admin] "One Less Dart to Hit the Bullseye" Please welcome @jarriaun and listen to the podcast to discover what is coming your way this week - https://t.co/8UpgMlSm1X
Hi everyone! Super honored to be here! I am Jarriaun Streets, a Sr. Biological Scientist in the field of nanotechnology, specifically pharmaceutical sciences! Today, I’ll be discussing my journey into nanotechnology 🥳🥳 https://t.co/Nwt7VNdmkO
Before I start, I want to highlight @BlackinNanotech as we are celebrating our first ever #BlackinNanoWeek this week! #BlackinNano is co-founded by myself and @O_Ganics #BlackinNanoRollCall is currently happening! Stop by and introduce yourself if you are in the field! 🤗
So my journey began in the summer of 2017, it was an undergraduate requirement to complete a senior research topic at Florida Gulf Coast University (@fgcu)
As a biology major, I was already aware of the various research labs and professors recruiting students to do research in their labs. But not sure of which direction I wanted to go in https://t.co/xqkUFuMpN7
One of my favorite professors by the name of Dr. Kerry J. Lee happened to have only one spot left for her research lab that dealt with nanotechnology. But at the time, I had very limited knowledge of nanoparticles. I was nervous, but I was intrigued! https://t.co/wFPdmKduW7
Anyway, I was so happy to be a part of her lab!! I began working with a few other students and our senior research project was a group effort! I will go into more detail about our research tomorrow, but we were assigned silver nanoparticles to use a optical probes 👀 https://t.co/wwWnl0nAbL
I knew that I really loved working with nanoparticles and I began seeking options to study it more. Dr. Lee knew of a new program at the University of South Florida and she encouraged me to apply
Fast Forward to May 2018, I completed my research and graduated from FGCU with a Bachelor’s degree in Biology and a minor in anthropology! https://t.co/YOfI5w7RLy
I took a semester off to work as I completed my applications to graduate schools. One of the most rewarding jobs I’ve had was working for an agency named PAPA (People Assisting People Aging). I spent my semester building relationships with the senior population
I would take my clients shopping, to Dr. appointments, and other fun outings during the entire Fall of 2018. I will always cherish the good times I shared with my clients 🥺❤️
Also during this time, I learned that I had got accepted into the M.S. in Pharmaceutical Nanotechnology Program at USF and I would start in the Spring of 2019!! I was going on my way to being a scientist!! 🥳🎉🙌🏾 https://t.co/cngxzPUwXA
RT @MatSciMatt: @RealSci_Nano Yay for undergrad nano research!
So I’m May 2019, I moved away from home and started the MSPN program. From day 1, I was in LOVE with the curriculum. Within the program, there are 3 tracks. 1) Research 2) Entrepreneurship 3) General
I knew that I wanted to continue actively working with materials and I applied for the research track and I was accepted and I made the commitment to work in Dr. Vijaykumar Sutariya’s lab to complete my thesis.
I spent the entire Summer of 2019 researching, observing, and writing literature reviews to find a thesis topic. The focus of his lab is using polymeric nanoparticles to improve drug delivery to the posterior segment of the eye to potentially treat AMD.
I’ll get into my thesis research more on Wednesday, but long story short, I completed my thesis and graduated with honors this May with a Master’s in Pharmaceutical Nanotechnology! https://t.co/1197FLikk1
All of this in the middle of a pandemic may I add 😂 Anyway, my degree opened up so many doors for me. I began working as a Sr. Biological Scientist in the Pharmaceutical sciences department which allows me to still use nanoparticles in my research 🥳
Good afternoon everyone!! Today, we’ll be delving into my undergraduate research with silver nanoparticles 🥳 https://t.co/cJHXZ6XcyN
RT @dr_cgeneus: @RealSci_Nano @O_Ganics @BlackinNanotech Co-Founder yall! Go Jarriaun 👏🏾
@DishPodcast Oh wow! Seems super exciting!! 🙌🏾
Today is also DAY 2 of #BlackinNanoWeek 👇🏾 https://t.co/GmI8g2IxCa
RT @BlackinNanotech: Day 2 of #BlackinNanoWeek We want to feature YOUR video on our page 🗣 Go ahead and get your video camera ready 🥳…
Bacteria cells, in this case MRSA, contain efflux pumps that are able to resist treatment due to their ability to efflux multiple drugs outside of the cell
Because of this, this allows cytotoxic escape in both bacterial infections and cancers. Studying the kinetics of these efflux pumps allows us to provide more efficient treatment
We studied the kinetics of these efflux pumps by using Silver (Ag) Nanoparticles as optical probes in MRSA cells and observed them in real-time under Dark-Field Optical Microscopy, or DFOM https://t.co/cBqVYBSYVd
I called AgNPs “biological glitter” because there are 3 colors that are exhibited under the DFOM. Red, Blue, and Green! The same as primary colors 🥺
However, these 3 colors are indicative of different sizes of the AgNPs and the smallest of the 3 are blue, while red seemed to be the largest https://t.co/rilkJKiHD7
This is how the AgNPs loaded into the MRSA cells appear under the DFOM. See if you can spot all 3 colors!! 👀 *Side note: Dust is also really pretty under a DFOM 😂 https://t.co/1OtRnfNlrH
When the AgNPs are on the outside of the MRSA cells, they appear bright (pictured above), but when they are inside the cell, the intensity is very dim. This is how we are able to know if the AgNPs are inside of the cells
We used the DFOM to record real-time of this constant in and out of the cells in 20 minute intervals. From the recordings, we are able to obtain snapshots at different time points as well so we can count the cells
After counting, we were able to create this graph to visualize the AgNPs that were most prominent. In Trials 1 & 2, Blue was the most successful spending about an hour in the MRSA cells. Green and red AgNPs did not last as long. https://t.co/LZUcFEynyQ
From these results, we can conclude that smaller, blue AgNPs were the most effective at staying inside of the MRSA cells. Thus, these results are promising to the future of drug delivery. Here’s why!!
If we are one day, able to combine these AgNPs with a drug to treat these bacterial infections, we are on our way to more efficient treatment! Also, we decrease the risk of these efflux pumps eliminating drugs before they get a chance to work.
So it turns out ✨biological glitter✨ is actually pretty useful! Let me know if you all have any questions!! https://t.co/yaujP1YXKr
After all of my research jargon, let’s take a minute to do some deep breathing exercises. It’s 9:05 pm where I am and it’s a great way to relax yourself before sleeping 🧘🏾♀️ https://t.co/f5KAFaePWQ
[admin] "One Less Dart to Hit the Bullseye" Extended conversation with @jarriaun is out now! Jarrium, in additon to her science, also spoke about @BlackinNanotech 🎊😀 https://t.co/5acryc6z9E
DAY 3 of #BlackinNanoWeek begins at 11 AM EST. Be sure to register and tap in! https://t.co/jhR2ksYZpO
Rise and shine all! ☀️ Today, we get to the nitty gritty of my thesis research, but before I get too in depth, here’s an appetizer version 🍱 https://t.co/S98z1yLIQT
Tune in to Dr. Haynes as she discusses her research, happening now! Join us https://t.co/qaZAbsExOc
So my Master’s thesis was based upon improving drug delivery to the posterior segment of the eye to better treat Age-Related Macular Degeneration https://t.co/Yh2aoc8qsH
In order to achieve this, I decided to use a MPEG-PCL micelles to encapsulate my drug. These polymeric nanoparticles are favorable due to their minuscule size and their proven biocompatibility
The preparation of these nanoparticles include the sonification of MPEG-PCL polymer (A) and the anti-VEGF drug Sunitinib malate (B) into one mixture seen in the figure below https://t.co/ChLN86joP7
After prep, we confirmed the efficacy of our SM-MPEG-PCL formulation by using DSC Analysis. Chaotic, I know, but I can explain! https://t.co/azm3gKcI01
Peaks represent a melting point for each of the 4 samples (Formulation, Drug, Polymer, and Physical mixture of drug & polymer)
DSC Analysis confirmed that the nanoparticle formulation is stable and the drug was properly loaded into the polymer
Further analysis included particle size, zeta potential, entrapment efficiency (~64.3%) for this particular formulation. The first picture is an TEM image of the size range of the nanoparticles seen here https://t.co/MSsS4owAN8
MTT Assay of our formulation reported a cell viability of >88% for all concentrations at both 24 and 48h. 100% viability at 10 & 20 μM. Meaning that our formulation is nontoxic to ARPE-19 cells
We also performed an anti-VEGF ELISA with the formulation and the analysis showed that the drug solution and formulation reduced VEGF expression up to 72h
Here is the research poster for more detail. This poster was recently awarded 3rd place in the NanoFlorida International Conference 2020! 🎉🎊🙌🏾 https://t.co/45fxePLzYF
@clh731 @BlackinNanotech Thank you Christy for tuning in! We’re glad you enjoyed it 😊
Also, here is the link to read the published manuscript on my thesis research. https://t.co/MsXLUqXXfx
RT @BlackinNanotech: Thursday (tomorrow) 👇🏾🗣 Q&A Panel with @cadalyjr @drjahayes @ChemWrg @ackun_amatata - 11:00AM (EST) / 8:00AM (PT) / 1…
RT @RealSci_Nano: So my Master’s thesis was based upon improving drug delivery to the posterior segment of the eye to better treat Age-Rela…
Be sure to tap in at 7:30 EST! https://t.co/KwSnVdra6t
If you’re interested in Nanotechnology degrees, we have 3 schools showcasing their MS and PhD programs today starting at 10 AM EST!! #BlackinNanoWeek https://t.co/7Q2sSCPrFu
If you would like to learn more about the program that changed my life, join us at the informational today at 2 PM EST using the link below https://t.co/ftxInrG4sN
RT @BlackinNanotech: UP NEXT at 2 PM EST: James Lambert from The University of South Florida will be presenting their MSPN program Zoom L…
Hi everyone, Jarriaun here, it has been an honor curating the page and sharing my research. Thank you all for letting me celebrate #BlackinNanoWeek with you all! Feel free to follow my personal page: @jarriaun Also, follow @BlackinNanotech as our mission will continue! 🤗
[admin] Thank you @jarriaun for curating the account last week and telling us about your science and @BlackinNanotech updates! Do give her a follow! Podcasts featuring Jarrium are here - #97 https://t.co/8UpgMlSm1X #98 https://t.co/5acryc6z9E https://t.co/tw4L7ZjdKu
Andres Castellanos-Gomez
[admin] "Stretching Atomically Thin Materials" Please welcome @Andres_2DMat and listen to the podcast to know what is coming your way this week - https://t.co/Bk3dLZCrCW
(1/5) Hi #Sci_Twitter, I'll be curating the @RealSci_Nano account along this week. I'll introduce myself in this thread. My name is Andres Castellanos-Gomez (@Andres_2DMat), I'm a tenured scientist at @icmmcsic and I work on 2D mater. I did my PhD at @fmcatuam (2007-2011)
(2/5) Then a postdoc at @tudelft (2011-2014) in the Netherlands. After that I got a tenure-track position at @IMDEA_Nano (2015-2017) and in 2017 I got tenured at @icmmcsic where I settled my lab which is part of the @2d_foundry research group.
(3/5) I am currently focused on the study of optoelectronics and nanomechanics in two-dimensional semiconductor materials. More specifically on 'straintronic' devices based on 2D materials (devices where the application of an external deformation lead to a change in their output) https://t.co/tH68Dw0xUW
(4/5) In this picture you can see the members of my research group. We are a rather young and small group, but we are nonetheless quite motivated and active 💪. You can find more info about the group at: https://t.co/GIr2bkMkde https://t.co/1LQpe23TIF
(5/5) Along this week I will tweet about how I reached here, about my ongoing research and about the daily-day of a 'young' PI. If you have any question please don't hesitate to contact!
(1/6) I am going to start the week with a confession 😱. How I ended up studying MoS2 and other 2D materials when everybody was so obsessed with graphene? Thread in! 👇
(2/6) Well... I started my PhD in 2007 when everybody was indeed obsessed with graphene and I came accross these two jewels. Two very humble papers amongst all the crowd of high impact papers about graphene... https://t.co/BKRTtlwIHW
(3/6) Of course Novoselov and Geim already demonstrated in 2005 the exfoliation of other 2D materials beyond graphene in a seminal paper but it seemed that nobody really cared about these other 2Ds! Can you believe it? In 2 years only Ayari's paper focused on other 2D materials! https://t.co/OjgZfBFJPd
(4/6) I cannot recall exactly why I got so interested in these other 2Ds. But I kind or remember that I thougth that it was a slower field where I could be (freshman PhD student in a small group without experience on the field) more competitive.
(5/6) So in early 2008 I bought a small crystal of MoS2 from SPI and I borrowed a tape with exfoliated NbSe2 from a lab neighbour Vanesa Peña. She was studying single-crystal NbSe2 with low temperature STM and she was cleaving the crystal with tape everytime she prepared a sample https://t.co/tHARlIBBgn
(6/6) That lead to the first manuscript of my thesis about other 2D materials. It was sent at the end of 2009 and it triggered the love story that I still have with 2D materials beyond graphene https://t.co/HSLw6OZY3z
How do you start your day? @RealSci_Nano starts by checking the "news"! https://t.co/1Mke59fEsc
@CaboAntonija I am a tea-at-home coffe-at-lab person 😉
@igordownunder Yep, being working on these "2Ds beyond graphene" for a while already... Not sure when (or if) I will become bored of them 😉
#DailyDayInTheLab 2 weeks ago we came across a just accepted manuscript that overlaps ≈70% with the manuscript we were starting to draft. Now working full speed on our manuscript to avoid it dying inside a computer folder 📂. #sciencetwitter #phdchat https://t.co/pzjuBC5dca
[admin] "Stretching Atomically Thin Materials" Longer conversation with @Andres_2DMat is out now - https://t.co/QN0jCHq363
#DailyDayInTheLab more and more online seminars in the agenda. It's more tiring than regular ones but gives the opportunity to exchange into with many groups around the world 🌍! https://t.co/54ebfvfCmI
#DailyDayInTheLab. A common curse for 'young' PIs is that we get to spend more and more time in the office and less and less time in the lab. BUT I have hacked this problem... Experimental setups *in the office* 😎 https://t.co/44qnQwiRMW
@A_DguezAlfaro Son parte de la oficina, como la probe station 😉
@IfanStephens @DavidDye9 In the meantime this is still my working-from-home setup! 🤣 No question why I am so eager to go to the lab so often https://t.co/5NmNQlBfcU
How are your #FridayAfternoonExperiments going? Here I am moving flakes of 2D materials https://t.co/25x0IwfSWQ
RT @Andres_2DMat: If you liked this #FridayAfternoonExperiment you might want to take a look to this old work where we used a sharp AFM tip…
My week as curator of @RealSci_Nano is coming to its end. I was planning to share more stuff but I was crushed by all the pre-holidays deadlines 😓. I hope that it was OKish. If you want to hear more updates of my Lab you can follow @Andres_2DMat.
I've been sent back until my task is done! https://t.co/lFB4nG5IEJ
Apparently I am the last curator of the year so I can tweet a little bit longer
One of the last days before holidays it's a perfect moment to set up a homebuilt anti-vibration table for our microscopes at Castellanos Lab (@Andres_2DMat). Still few more adjustments to be made after holidays https://t.co/9liPSGwrAX
Did I get an invitation to review a manuscript yesterday evening? Yep, I did. It seems that the Editor's job never stops. https://t.co/6M7ds0RLnR
I always wonder about the authors that send their manuscript a 23rd Dec... Don't they think that the Editor will have troubles to secure referees? Will be the referees happy to review an article these days? Or they will have an unconscious bias?
I try to avoid sending manuscripts between the 10th Dec and 10th Jan as much as possible. Anybody else?
@Felgraf_Physics Yes, some revised version resubmission or some manuscript that cannot wait (scooped or about to be scooped) or things like that (happened to me few times). But IMHO many many manuscripts could easily wait until the 10th Jan when everything goes back to normal
[admin] "Stretching Atomically Thin Materials" Thank you @Andres_2DMat for amazing weeks of science. Listen to the podcasts to know more about Andres's research - #99 https://t.co/Bk3dLZCrCW #100 https://t.co/QN0jCHq363
2021
Anna Ploszajski
[admin] "Telling Dramatic Stories in Materials Science" Please welcome the first curator of 2021 - @AnnaPloszajski Listen to the podcast to know what is coming your way this week 👇😄 https://t.co/krlMxduLND
Hey gang! This is @AnnaPloszajski here signing on to the account this week. I'm a materials scientist, writer and storyteller based in London. I'm interested in how we can tell compelling, engaging and believable stories about science. What's your favourite science story? https://t.co/Cn4r9XVUVv
@lonbarfield @AnnaPloszajski ... I'm listening!
Over the last few years I've been applying storytelling theory to popular and academic science communication. Do you think science (papers, theses, conference presentations etc) should aim to entertain as well as inform?
Morning all! Let's talk about communicating nanoscience, a field famously invisible to the naked eye. So what are the best ways to engage with the public on nanoscience? https://t.co/z7NpyRoxB4
I guess there's microscopy images or digital mock-ups of molecules and structures, but without any context these can sometimes raise more questions than they helpfully answer. https://t.co/pajCtKerP5
What about demonstrations? Can be great if they go right but sometimes that's quite a major if! https://t.co/umDJzcgEF1
How about writing? What are your favourite books about nanoscience and don't say Donald Trump's memoir. https://t.co/snu3wGY4FK
@zang808 Okay I need to hear more about this!
@zang808 Oh awesome I'm definitely going to check this out!
And then there's TV and movies. What are your favourite TV shows and movies that actually communicate correct nanoscience? https://t.co/6LAjSHgirc
@jhnmcdnld43 Public engagement should be a 2-way process, so the public learn from researchers, but researchers learn from the public. It can be a really valuable way of understanding how society views the science you do, and can even influence research directions when done right!
@lonbarfield @AnnaPloszajski Omg! What did they do with it?
@jhnmcdnld43 You mean the more people find out about nanoscience, the more skeptical it might make them?
@jhnmcdnld43 Well in that case it's the scientist's responsibility to communicate the science effectively enough that the public aren't appalled/confused by it.
@lonbarfield @AnnaPloszajski Ha omg 🤣
Let's talk podcasts! I've been running mine, @rialtalk, for a number of years, talking to artists and craftspeople about the materials they use in their work. What are your fave podcasts which manage to communicate (nano)science in an engaging way? https://t.co/RruOK2lBkN
[admin] "Telling Dramatic Stories in Materials Science" Extended conversation with the amazing @AnnaPloszajski is out now, do give it a listen 👇🎙️ https://t.co/pVwDOyO2S3
@nlidgi @jubobroff Ooh thanks for sharing!
@davis_susannah @rialtalk @SciHistoryOrg Ooh this sounds amazing!
Morning all! Today I'll be sharing my tips and tricks for how we can use storytelling to communicate science better, not just communicating it to the public, but to each other too. 🧵 https://t.co/UzKJpfgEmO
First up: STRUCTURE. I often teach researchers about the Hero's Journey story structure. It's how many of us will intuitively tell stories anyway, but it's a helpful double-check of whether all the compelling details are in there... https://t.co/nfElEVAocx
For example, in the Results sections of many papers, experiments are often presented in a seemingly random order. The HJ says that all actions should be causal, and occur because of what came before. That's how we do science! But that's not often well-communicated in papers...
Second is CHARACTERISATION. We're trained as scientists to write/speak in the passive voice; "the experiment was done". Science is done by flawed humans, and I believe it's important to give scientists agency by including them in the stories we tell as we communicate the science.
@nlidgi Ooh that's a really interesting distinction. I've definitely seen 'we' used increasingly in English, but it's definitely not mainstream.
Kwasi Kwakwa
[admin] "Building Microscopes for Fun & Health" Please welcome Kwasi (@Olu_GH) and listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/RRqgR18a6D
Hi All, my name is Kwasi(@Olu_GH) and I will be taking over the account for this week. I am a physicist and Imaging Scientist, which is a fancy way of saying "person who works on microscopes"
I don't know if people necessarily think about microscopy when they think 'Nano', but since a lot of what I'm looking at is in the tens-hundreds of nanometres time scale, I'd say we quality
A rough schedule for what I'll be tweeting about is: Monday: Who I am/how I got here. Tuesday: an intro to microscopy Wednesday: A day in lab Thursday: Race/diversity in science Friday: hobbies Saturday:Ask me Anything Sunday: Careers in science
I guess we will start today with me talking about myself, something I simultaneously love and loathe doing. THREAD
I was born and raised in Ghana, West Africa. Like all Ghanaians I am incredibly proud of my country, but kinda low-key about it. I will say that we make the best Jollof though https://t.co/IyQK6T5wAj
Like most African families, mine pushed education hard. My parents both came of age just as Ghana gained independence from Britain, and were consequently part of the first generation for whom a university education was even possible.....
...and so nothing less was ever going to be good enough for their kids. I was never a particularly disciplined student, but I worked hard at things I liked and I am pathologically curious, so I did well almost despite myself
After primary and secondary school in Ghana I got a scholarship to Oberlin College in Ohio to study electrical engineering. Oberlin didn't have an engineering department so the idea was you did three years there and then transferred to another university for the last two
RT @Imp_Prov: Do you have an old laptop or tablet that you're no longer using? @TheServiceDesk have launched a new initiative for @imperial…
RT @jesswade: learn how to edit @wikipedia w/ me and @webmz_ for @Imperial600’s LGBT history month celebrations 🏳️🌈🏳️⚧️ feb 26, 14–16:3…
I started taking physics classes in my first year, changed my major, and never left, so instead I ended up with a BA in Physics. I do not regret this decision at all
Post-undergrad the plan had been to start grad school straight away, but I was kinda burned out for various reasons, so I lived in Cleveland for a year taking Masters level classes and working as a lab assistant, then I moved to New Jersey to start up a PhD that I hated....
Around about the same time my mother got sick, so the combination of burnout, being unhappy with where I was and being worried about her led to me taking a temporary leave of absence that turned permanent, and I moved back home to Ghana
In Ghana, I got a job working in a government IT research/training institute where I looked after a compute cluster, taught basic programming classes, consulted with national universes and generally ran around doing a bit of everything. It was hard and wonderful, but not enough
So.. a little over a year later I ended up in London to do an MRes in physics, specialising in photonics. The actual research was building computer simulations to understand the plasmonic responses of silver nanoparticles that were being used in imaging
(don't worry, I will explain what that is tomorrow, complete with pictures)
After the masters, One of my supervisors had that holiest of grails, research funding that could go to a non-British, Non-EU student, and he had an imaging project he thought I'd be good for
The project was a mixture of microscope building, imaging and image analysis, and I hadn't done any real experimental work in years outside of supervising undergraduate labs. But I was good with my hands and the project sounded fun, plus he had funding so.....
For the next three years, I primarily worked at National Physical Laboratory in Teddington and learning a ton about microscope building and single molecule imaging to build a microscope and work on a technique for measuring the orientation of single fluorescent molecules
Post PhD, I then ended up at Imperial College working in a photonics lab and working on ways to perform super-resolution microscopy on the cheap, so it was another learning curve on picking up a new technique, but tremendous fun
After 3 years at Imperial and leaving behind a working microscope, I moved to UCL to split time between an AFM lab, and EM lab and a fluorescence microscopy lab. This time less instrument development and more time on a specific problem, with a few side projects
@ProfRachelGaN Thanks Rachel, glad you are enjoying it :)
This still remains my favorite side project, helping build a light sheet microscope out of mostly leftover gear in the lab https://t.co/yaQoKX3m8b
RT @BlackinNanotech: As part of our initiative, Black in Nanotechnology is excited to announce its partnership with EMO-Haiti (@emohaiti) t…
@schrodingerskit I know of his work, but don't think we have ever met. They do really cool stuff. That looks very different from what you ended up doing
And now on to the current gig, which finally took me out of London to Cambridge I am now am imaging scientist at @emblebi and working with some very smart people to build hardware and software platforms for high throughput spatial transcriptomics
less buzzwordy version, we use microscopes to image active genes inside cells, except we want to be able to image hundreds of genes in hundreds of thousands of cells, and do it as fast as possible
@alicepyne yeah, we worked for the same person for our Phds and didn't meet until years after! Very small world
@schrodingerskit looks like things still worked out great for you though :)
RT @DrAnneCarpenter: PhD biologists who love microscopy and have a knack for software… join my lab and learn new skills! https://t.co/xAm3L…
@alicepyne https://t.co/t4vGdNbqTn
@tanvir_h https://t.co/iIbOEWyapE
It just means that every morning is a slooow start https://t.co/pImiddUo4n
@idrismonsur @Olu_GH It is self-evidently true, and all disputes are fake news!
RT @Claudia_May6: I would like to say a MASSIVE thank you to the snow fairy who put snow ducks around Bath. 🐤🌨 https://t.co/xhD5vRHjIB
@martinjones78 @alicepyne I don't think so, but NPL was very.... insular So not hard at all to never talk to people who worked not too far from you
RT @vagina_museum: You know, if you're going to publish a paper arguing that sex differences are partly causing the gender disparity in STE…
@alicepyne @martinjones78 lol, we could use other words, but I figure Martin's friend has already told him some things
RT @RuchiPL: So relatable!! 😂😂😂 https://t.co/JMaiRmxckl
RT @nlidgi: "supplementary informations" is the new "footnote"
RT @AndrewAllan9: Finishing testing of an interesting upright configuration with @NikonInst FN1, @OlympusLifeSci Tri-noc & @Photometrics Ki…
RT @RMS_EarlyCareer: This weeks #ImageAnalysis tool is MLAEDT-3D; a Python package to compute the Euclidean Distance Transform of a 1d, 2d,…
RT @MySci_PK: 🏃♀️ during snowfall, check! https://t.co/x7AUjU0ZMM
Hi All! Apologies for the silence yesterday, I ended up having a later day than planned, so today we will attempt to cram 2 days worth of tweets into one. Which also means two days worth of pictures
So, How does someone end up working on microscopes with a physics degree? Well, physics includes the study of electromagnetism, one of the fundamental forces of nature. (Image courtesy of Wikipedia) https://t.co/g9I71calIB
Optics, the bit of physics that studies the interaction of light and matter, is kinda a subset of electromagnetism, and it is an important part of how we build everything from glasses to the lenses on your cellphone cameras to how we build microscopes
So among the *many* strange corners of physics, there are labs that basically spend all their time applying these principles to trying to build fancier and fancier microscopes
this is not the only weird corner of physics involving optics btw, there are people out there levitating tiny bits of matter with lasers or using them to observe physical phenomena that happen on the pico-femtosecond time scale (under a trillionth of a second)
That said, the study of optics actually predates the existence of physics as a formal field of study. My favorite ancient optical physicist was Ibn al-Haytham, a Muslim scientist born what is now Iraq in the late 900s
He was a mathematician, an astronomer, a translator of ancient works and an actually foundational thinker in the field which I now work over a thousand years later (picture also courtesy of Wikipedia) https://t.co/3sX95opXxW
[admin] "Building Microscopes for Fun & Health" Extended conversation with the amazing @Olu_GH is out now. In this podcast, Kwasi speaks at length about his science journey, current research and learnings from 2020. https://t.co/ayOe95Wc32
RT @realscientists: [admin] "Building Microscopes for Fun & Health" Extended conversation with the amazing @RealSci_Nano curator of this…
RT @MinoritySTEM: I'll be back in a few to spare my eyes from RStudio screen staring, but YOU tell me: if you're in STEM, what was your "ga…
Now we can move on to talking about microscopes proper. For people who don't work with them for a living, you probably haven't seen once since school and you remember them looking like this https://t.co/Y3DF2OIXw5
The strange thing is, that's not hugely different from what microscopes looked like for a long time. Original microscope design in the 1600s looked like this. A single ball of glass in a metal holder https://t.co/ZnDOb6qvR4
Within a century though, they looked like this. And that fundamental design did't change hugely for a long time. Lens building got better, people figured out how to use bright lamps for light sources and focus them in samples, but the basic design didn't change too much https://t.co/xP08yKbOUZ
So... What do they look like now? Here are some examples of systems I have worked on/with https://t.co/FzBvzXBecv
If those don't look like you expect, it is because the last 3 decades or so have massively changed what microscopes look like and the ways they are used, and that change is accelerating
The cause of those changes? Also Physics (I may be a tad biased) Basically optics got a little better, but what has really driven innovation has been three kinda connected things. Computing power, lasers and image sensors
I say connected, because all three things exist because we discovered quantum physics in the mid 20th century and then applied it to understanding how materials behave. Hence solid state physics, hence lasers and transistors, hence the field that makes me a living
Why lasers? Because most modern microscopy methods use a principle called fluorescence. Basically, you shine light of a specific wavelength/colour on a material, it absorbs that light and it emits light back at a different colour (purple laser, blue fluorescence on the right) https://t.co/rfVbDhTaj7
Lasers allow us to deliver very bright light to a specific point in space, which is great for lighting up samples to be imaged. We use some fancy biochemistry to stick fluorescent molecules to the things we want to, we hit them with bright light, and we take a picture
RT @ShroukELA: My company is hiring! Lots of roles, including for bold and creative engineers looking for Electronic Engineering roles in M…
To go one level down, why fluorescence? Because a cell is basically a sack made of fatty acids in which a whole bunch of chemistry happens. Most of the stuff biologists care about is transparent, so we have to label it to look at it
Next, Image sensors, also known as the piece of silicon in your digital camera that actually collects the light and converts it to a digital signal.
Quick bit of history: Early microscopists looked through the glass and drew what they saw by hand. Then film cameras came along and people started mounting film cameras on microscopes, taking pictures of they samples, and developing them
Then we got point detectors, which were sort of like reverse CRT screens. they could convert a spot of light focused on them into an electrical signal, so you could scan a point of light across a sample and record the light coming back one point at a time
These existed in parallel with film for a while, because for some kinds of microscopy, point detectors didn't make much practical sense
Then came image sensors, and all of a sudden biological images could be pushed directly from a microscope to a PC without a few hours of messing around with chemicals
Also image sensor technology kept advancing and got so sensitive that they could detect single photons of light, so microscopes could "see" things that had previously been invisible
Nowadays the kind of image sensors that end up in scientific cameras are almost as sensitive as the most sensitive point detectors, and almost as fast, but they can take a singe image at once instead of one point at a time, so they are more useful for most kinds of microscopy
And the thing that ties them all together, faster computers. To get why computers matter so much here it helps to realize that a digital image is a picture represented as a series of numbers, and you can therefore use maths to 'see' things in the image...
Since computers are good at maths, and since cameras can pump out images as fast as computers can see them, you can now create computerized tools for looking at pictures and extracting interesting data out of them
So basically the kind of maths that can be used to recognise faces in photos can also be used to do things like count cells, measure their sizes and shapes, track their movements etc. etc.
You tie all of this together and all of a sudden microscopes become big data tools that can take incredibly large numbers of pictures of impossibly small amounts of light inside cells and turn that into numbers that tell us what is going on
@danguyf That is *very* much a thing. And probably going to be for years to come
@j_asimeng Glad you liked it!
@ReynaudEmmanuel Oh, that is pretty! Imperial Photonics have a small collection of microscopes sitting on a shelf that have to be at least a century old at this point
@Srikanthislive @MySci_PK I'm glad you find it interesting :)
@DanBumbarger I still love just looking at the images, but I guess the curse of coming at biology from a physics perspective is I always find a small voice in the back of my head going "now can we measure that and get numbers for what is happening......."
RT @LamSonLeoc: What is a modern microscope? Optics for sure, but also chemistry, solid-state physics, computer science and math. https://t…
RT @GentlemanLab: I can't believe it! 🥳😎🥳Our organoids are on the cover of @NatureMaterials! Check out our paper combining synthetic hydrog…
RT @ZJAyres: PhD students often come to me with concerns they don't have skills for jobs outside of academia. You *absolutely* do. So here'…
@ReynaudEmmanuel 🤤 That is a beautiful piece of kit
Hello All, I I'm back for day three. Today is supposed to be when I talk about things I do when I'm not sciencing. Before I dive in, what do you all do for fun?
RT @LSI_Exeter: It's a new year, time to restart our External seminar series! We are delighted to welcome Prof Ricardo Henriques @Henriques…
RT @BioImagingUK: Looking forward to your talk today at 4pm GMT, Steve! Sign up to our mailing list to get details of the first BioImagingU…
@martinjones78 @MelodyBlackman I don't think I ever realized how big your dogs were until this picture
@LaineBioImaging The perfect lockdown activity
@ReynaudEmmanuel I'd love to. Once we get past the current craziness, feel free to pencil me in! Especially if we get to test out that illumination system
RT @ManuelTHERY: I couldn't prepare a lesson on mitosis without the pictures of Alexey Khodjakov. #microtubules are in green, @intermediate…
RT @hephaix: @RealSci_Nano @pierrekerner https://t.co/FCwKRslBUH
In my case, I'm what one of my cousins describes as a "serial hobbyist"
I tend to bounce around and try a lot of things. A few of them stick around permanently. Being at home a lot more than normal has been good for trying new things though
The thing I miss the most these days is Judo. I picked it up just before I moved to the UK and it kept me sane through the masters and especially the PhD. Still one of my absolute favourite things
That photo is from the day I was officially awarded my black belt. Still kinda a big deal even now https://t.co/cJf0baHiPb
While we are putting up photos. This is me and an old friend posing with Neil Adams, double Olympic silver medalist and the first British man to win a world championship https://t.co/pIC6yqPElG
To put into context how big a part of my life the sport has been, this is the house share I lived in during my PhD. Three of the four of us did judo regularly, so this is less than a week's worth of laundry. https://t.co/kHW4iiVf79
Although, me getting into any kind of sport would have been incredibly surprising to anyone who knew me befire about the age of 19. I spent my childhood with my nose in a books and comics at all times. Still do, I'm a long time comixology user...
And a longtime science fiction(books, TV, movies) fan.
Just to toss a bomb in the crowd, still a fan of both Star Wars and Star Trek, but Trek is doing more interesting stuff this days
@dgaboriau Nice! No neighbors too close then?
@VUCellImaging Yeah, it is amazing how any reasonable-sized microscope facility sooner or later ends up having to care a *lot* about data storage
@jangray yup, Cryo-EM is another really cool technique that has been created by computers and image sensors
@JeremyNeuro D&D is probably the only stereotypically geeky thing I never really got into. I always thought I would at some point, but just never got around to it
since COVID and all the time I've spent at home, the things that have kept me sane have been (a) Picking up road cycling https://t.co/aNoV1ywDhw
and (b) starting to shoot and develop film. The little beauty below is my walking companion most days https://t.co/6jicH5dv9r
@afsb2013 sure. DM me on my main account and I'll be happy to help in any way I can
@images_and_beer lol, Is this really the place for my rant about the continued use of RS232 in the 21st century? That said, now getting more native USB kit finally
I occasionally tweet about it too https://t.co/394JOJrbaX
RT @BlackInChem: If you would like to be a part of the Core Planning Team for this year's #BlackinChem events and make a world wide impact…
@images_and_beer That is true, and now we may send them off :)
RT @OdedRechavi: peer review training for early career scientists https://t.co/wwwGzKfFqh
RT @KGoepfrich: WANTED: A #postdoc with experience in DNA origami or high-speed AFM, data analysis & a strong interest in synthetic biology…
RT @russelldavies63: Folks! I can't answer everyone's #ItsASin messages, I'd disappear. But cast and crew are astonished and delighted by t…
Happy Friday everyone! I just looked at my twitter schedule and realized that I was supposed to talk about race/diversity issues in science yesterday and hobbies today. Well, I guess we are going to have to reverse things
To begin with, a question to the audience: Do you think there is science has problems with diversity?
Follow up question: If you do or don't, why?
follow up to the follow up. Are there books/articles/papers you would recommend to people thinking about these questions
RT @jqfonseca: As "kind of" an engineer, working closely with aerospace, I can't but help thinking of COVID deaths in terms of airplane cra…
RT @ChanZuckerberg: Must read thread on the history of microscopes and current technology 🔬 And then explore how researchers are pushing t…
Pushing up these questions again before I start up properly today https://t.co/8ifFFmM0A5
Hi All, apologies for disappearing yesterday. This has been a busier week than originally planned. Thankfully it is now the weekend and I have done my customary Saturday chores and long walk, so I can settle in for the next couple of hours
So... who wants to talk about diversity issues in science! Or rather, who wants to listen to me rant and occasionally interject?
So where are we starting today? With a story about the microscope I already showed in this tweet https://t.co/TmA8cxgfSE
that microscope is based on the one that would have been used by Antonie van Leeuwenhoek, a Dutch businessman and scientist who lived in the mid 1600-early 1700s and is widely regarded as one of the foundational figures in the history of microscopy and microbiology
Sidenote: The businessman part is important because it is worth noting that a lot of the structures of modern science was created by wealthy European men working in their spare time. I'll talk a bit more later about why this matters
For now, the important thing is that van Leeuwenhoek made what were at the time incredibly sensitive microscopes, then applied them to looking discovering microscopic life. Including his own semen
(and yes, I have made all the jokes that I could think of about how he acquired his samples)
When van Leeuwenhoek and his assistants described what they saw while looking at semen, they all claimed to be able to see little people inside of the sperm cells they saw wriggling around
Now: (a) those microscopes probably weren't powerful enough to allow them to see tiny people inside of cells but more importantly (b) We know now that there are no tiny people inside sperm cells So why make the claim?
RT @Hayley_Barlow: TONIGHT: shocking Channel 4 News report reveals how hundreds of overseas students have become destitute in the UK during…
To understand that, you have to understand that there was a long history in western philosophy of the idea that men provided the "seeds" of what makes a person and women purely provided the "soil" for the new person to grow
... and those ideas had grown into a legitimate scientific theory by the time van Leeuwenhoek looked through his microscope at those sperm cells. He was aware of these ideas, probably took them seriously.....
...and so when he saw his own "seeds" it wasn't a huge step to conclude that there were actually people in them
the lesson here isn't that he set out to mislead people or that he was a bad scientist, it is that he was a man who grew up in a world that fed him certain ideas about how the world worked, and those ideas leaked into his observations of the world
(It is also worth noticing that science and philosophy in his era were both the domains of rich European men, and that had to have an effect on which ideas were considered legitimate and which weren't)
The lessons of this story: Science as a discipline is meant to be a completely objective context-free search for the truth, and sometimes scientists assume this means *we* are also magically objective creatures who exist only to search for the truth
In reality though, scientists are people, and like all people, we absorb the biases and prejudices of the societies we are surrounded are. And if we go on to build institutions, we embed those biases in them
we are surrounded *by* I desperately need a proof reader
Anyway, this observation becomes really important when you consider that, like I said earlier, the foundation of modern science were mostly erected over the last 500 years ago by a group almost exclusively made up of well-off European men
and baked into the institutions they created are a series of prejudices they inherited and formalised around race, gender, class, sexuality, disability etc.
And that process is as much a part of the history of science as the invention of the microscope or the discovery of DNA
Also, the consequences of that process live with us now, in terms of who is allowed to take part in the creation of new science and what kinds of questions are considered worthy of study
RT @Naresh10091986: 14 years of DNA origami. Excellent review @GothelfLab , Simmel and others https://t.co/kFERq1l2QY
RT @IBJIYONGI: People at Oxford and Cambridge keep asking me to give diversity talks for big events but they don’t offer honoraria because…
@KCLWCIC the Phenix?
@uastronomer A lot of the core technologies are pretty much the same, just used in different ways. From what I have read, modern astronomy is also becoming a weird sub-field of big data
sorta sidenote: I really think that people who claim to be interested in how science works should care as much about the ways it has been harnessed to defend inequality as they do about, say, Einstein
RT @ShakiraRHobbs: Today marks 2-years since I’ve been an assistant professor. And here’s what I learned so far:
@uastronomer yeah, I guess we have the advantage that our samples are small enough so we can redesign our tools to put them in different positions. Space is a bit harder to move around
RT @OdedRechavi: There’s a myth that scientists are awkward, uncoordinated and not athletic. I bet that’s not true & perhaps there’s even a…
@uastronomer microscopy borrowed a lot of ideas for adaptive optics and single molecule imaging from astronomy actually
*Especially* if you are in any kind of position of power. And this includes, say, being a TA in an undergraduate lab
If you are looking for examples of things you could read, these are from my bookshelf https://t.co/rHeTVrOfvN
I consider that a very basic starter list though. @IBJIYONGI has a more extensive list here https://t.co/8SUkBbCTWO
@KCLWCIC it is a great piece of kit so long as you use it in the PE universe. Otherwise things can get a little difficult
RT @xiaofei_lin: One of the reasons I'm leaving research after my PhD is because I had a past mentor early in grad school who treated me wi…
RT @LeenGoAGoGo: Love this thread about the evolution of microscopes! Thanks @RealSci_Nano !! https://t.co/g3JrAYTNgl
I'd be interested in an answer to this too. Any ideas? https://t.co/JeEJbkFgLk
RT @x_caret: Really amazing journey into what it’s now microscopy! https://t.co/tRk4XlqtMe
@YuriEliasR This is a good question, and there are people who spend substantial amounts of time trying to figure out what levels of laser power are toxic for living cells. I don't know if there are perfect answers at this point, but we generally try to keep power levels as low as we can
Hi all, Today is my last day curating this account, and I figured I'd spend today giving some advice about careers in science, but also answering any questions people might have
so if you have any questions, feel free to tweet at me and I'll see if I have something that looks like a sensible response
On science careers, I'm probably going to do something slightly unusual in that I'm going to recommend people *not* do most of the things I have done
RT @IgualdadLGBT: ¡Última Hora! Angola despenaliza la homosexualidad 🇦🇴🏳️🌈 https://t.co/17NbqAWR3y
Things I would recommend that I did: (a) Try really hard to work for decent people and avoid terrible ones (b) Follow what you find interesting/exciting
(c) Try to be a decent person yourself. Be the person who people in your circles know they can come to if they have a problem
Things I recommend that I am terrible at: (a) Invest *heavily* in time management skills. Make the best use you can of your work hours, be as productive as possible (b) Have long term plans. Have a feel for what you want your future to look like and plan for it
(c) Prioritize academic output. Don't put your name on terrible papers, but if you do anything actually interesting, get it published (d) Be tactical. Chase collaborations, chase speaking engagements, make sure important people know who you are
Also, be realistic about job prospects. Academic science in the 2020s is not a viable career path for the majority of the people who are skilled enough and motivated enough to do the work
...So keep an eye out on all of the possible career paths that exist outside of academia. And recognise that you aren't planning this because you are incapable of doing the work, but because you may not get a chance regardless
@YuriEliasR No worries! glad it was useful
@abha_val Thank you. I'm glad you have enjoyed it!
RT @BhavikAnilPatel: I’ve been working to support #AcademicMentalHealth training for those who have experienced #Racism. This great resourc…
RT @HenriquesLab: A considerable portion of lab pictures get classified by Google as "nightclub" https://t.co/abh7ELekG1
I was asked if I have any extra advice that especially counts if you are part of an underrepresented group. I'd say everything I said before applies, but even more so because the odds are worse....
Also, finding a support structure for yourself becomes incredibly vital, and especially one that understands the ways in which your experiences will not be like those of most of your colleagues
RT @theosanderson: Do you weigh out compounds to make buffers/media? 🧑🔬 I made a tool to help you, and me. Mixology interconverts all so…
@alicepyne Very pretty scenery
@jesswade I haven't done any Raman spectroscopy since my PhD. I remember the data analysis being a bit of a pain. Has it gotten any easier?
RT @i_jayas: I get asked about this often - about what marginalized people could do to overcome the systemic barriers in advancing their ca…
Bonus points: Pick up soft skills. Learn to write well, to make pretty figures, to give good speeches, to teach properly, to manage other people, to manage projects. Never a waste of time
RT @BlkInEngineerng: Are you the first in your family to get a PhD? first Black person at your university to get a PhD in your field? 1st p…
RT @DSP_SPE: 📢🚨Join @DSP_SPE in our upcoming expert panel 'Bursting the academic bubble / Au-delà des Murs de l’Université' We'll discuss t…
@ThenSheAppears It is next up, but kinda wondering if I have the capacity for it right now. I listened to an interview Russel Davies did about that time and I imagine it is as bad as the stuff I've read about that era in the states
SO what are people getting up to with their Sunday nights? I am being incredibly thrilling and ironing clothes in front of the TV
@alicepyne definitely!
@JoFeanelwa What do you think about the Instant Pot? l keep thinking about getting one
RT @ThePlanetaryGuy: This is an image of the surface of Mars, taken from orbit. Look closely. See the faint pair of parallel lines that z…
RT @airdlab: So important and skills we regularly work on in my lab because they will be useful no matter your career path. https://t.co/Qe…
RT @quantumcascade: Enjoy this free access state-of-the art overview of exciting and impactful developments in our field by many of its lea…
Ok people, I think I'm done for the night, and that was my last day running this account. Sorry for the gaps in communication, but I hope I kept it interesting for you anyway my tweets, but a lot less thought out, can be found at @Olu_GH
Thanks for your attention, and thanks to to @MySci_PK for being interested in what I might have to say. I hope you all have a great week!
RT @hamlinr1: Hey faculty! As someone who just read 500 letters of rec (as grad admissions chair), I’m here to tell you that no one EVER us…
@BGFCentral @hamlinr1 I really should be surprised but.....
[admin] Huge thank you to Kwasi for an amazing week of science, full of microscopes and much much more. Do give @Olu_GH a follow! Podcasts ft. Kwasi - Short - https://t.co/RRqgR18a6D Long - https://t.co/ayOe95Wc32 https://t.co/fYODffktsR
Otto Mustonen
[admin] "Strange World of Quantum Materials" Please welcome @OHJMustonen for a week of materials/nano science and listen to the podcast 👇 to know what is coming your way! https://t.co/jv8f4IBWkS
Hi everyone! My name is Otto Mustonen and it's my pleasure to curate Real Scientists Nano this week. I'm going to tweet about quantum materials and doing experiments at neutron and muon facilities. @OHJMustonen @isisneutronmuon @ILLGrenoble @msesheffield
Quantum materials is a research area in the intersection of physics, chemistry and materials science. The peculiarities of quantum mechanics give rise to exotic properties and states in these materials. This often involves the collective behavior of electrons. It's like magic. https://t.co/wBtMiAA4XN
Quantum materials include superconductors, multiferroics, quantum magnetism, topological insulators and Weyl semimetals etc. The unusual properties can be the total loss of electrical resistivity, massive quantum entangled states and even magnetic monopoles.
The applications of quantum materials are often related to quantum technologies in general such as quantum computing, but we all use these materials when we get an MRI or when we read data off a HDD.
The 2021 quantum materials roadmap gives an excellent overview of the different types of quantum materials and the main challenges in the field. It is also open access! https://t.co/y2TrhTnULn @IOPscience @IOPmaterials #quantummaterials #openaccess
@JoFeanelwa Hi Jo! I'll talk about superconductors tomorrow. Thanks again for recommending me for this!
RT @ILLGrenoble: With record-breaking high-pressure measurements @ILLGrenoble : direct tracking for the 1st time of the evolution of #magne…
In 1911, Heike Kamerlingh Onnes was investigating the properties of metals at very low temperatures. When he cooled mercury to below 4.2 K, its resistivity suddenly dropped to zero. He had discovered superconductivity. #superconductors #NobelPrize https://t.co/TFiPsYXo4P
This experiment was possible due to Kamerlingh Onnes' other great gift to science: liquid helium. Helium has the lowest boiling point of any gas at 4.2 K. It is used for cooling in almost all low-temperature physics. A good helium cryostat will get you down to 1.5 K. @OxInst https://t.co/V2mexWscGS
The superconducting state has two important properties: the absence of any resistivity and the expulsion of magnetic fields. The latter is called the Meissner effect (perfect diamagnetism), and is the reason why a magnet will levitate on top of a superconductor. #levitation https://t.co/qF5DKDGuR8
Coincidentally this is my absolutely favorite demo to show to students. I wish I had taken video to show you, it's awesome! And freaky! Safety note: liquid nitrogen is still very cold and bad for you, and make sure you're in a well-ventilated space.
RT @ZJAyres: Honestly, one of the best bits of advice for navigating academia (and life) is to find genuine joy in other peoples' success.…
Bardeen, Cooper and Schrieffer developed a microscopic theory of superconductivity. An electron moving in a crystal will feel resistance, but two electrons can pair up to move without resistance. At low temperatures these Cooper pairs condensate to form the superconducting state.
The pairs are bound by a weak interaction with the lattice, and can be easily broken up as temperature increases. Here's the weird part: the electrons in the Cooper pair are hundreds of nanometers apart and moving in opposite directions! https://t.co/ul2jqMKGGX
John Bardeen won the Nobel Prize in physics for both the BCS theory of superconductivity and for inventing the transistor. That is quite the legacy!
@JoFeanelwa Hi Jo! New Cooper pairs are formed spontaneously, because they have a lower energy than individual free electrons in a superconductor. The interaction between the pair is something that is just not strong. In the BCS theory it occurs via a lattice vibration (phonon).
@JoFeanelwa A negatively charged electron moving in the lattice of positively charged ions causes a small movement of the ions toward the electron. This displacement of the ions then attracts an electron moving in the opposite direction. This interaction binds the electrons into a pair. https://t.co/LmvuR1meh6
@JoFeanelwa The interaction via this displacement is surprisingly long range, so the electrons can get pretty far away form each other before separating (>100 nm). But yes!
@JoFeanelwa To be honest I don't know, but I don't think it can be done on the level of measuring the individual displacements of ions. The lattice vibrations (phonons) can be measured with techniques such as inelastic neutron scattering and it is possible to measure electron-phonon coupling
Conventional superconductors are metals or intermetallic compounds. In 1986, Bednorz and Müller discovered superconductivity in a ceramic copper oxide at 30 K, a temperature on the edge of what was thought possible by BCS theory. https://t.co/UkIFbU8SLn
The next year Chu and coworkers discovered YBCO (YBa2Cu3O7-d), a superconductor with a previously unthinkable critical temperature of over 90 K. This allowed the use of liquid nitrogen (77 K) instead of liquid helium (4.2 K) for cooling the material to the superconducting state. https://t.co/BFqKTSbdkq
Anderson proposed this high-Tc superconductivity might be related to a novel quantum state known as the resonating valence bond state (a type of quantum spin liquid). I'll talk more about this in relation to my own research later.
The high-Tc superconductors are very different from the materials before. They are ceramic instead of metallic, their parent phases are magnetic whereas magnetism usually destroys superconductivity, and they have layered structures with a superconducting CuO2 layer.
The high-Tc cuprate superconductors are part of quantum materials known as strongly correlated electron systems. These materials cannot be described using conventional band theory, which assumes individual electrons do not interact with each other.
This often involves materials with partially filled d or f shells, which are more localized on the ion compared to s and p orbitals and therefore interact more strongly. In the cuprates, the superconductivity arises from the interactions of the strongly correlated Cu2+ 3d9 states
RT @APSphysics: Don't miss the virtual First Day of Issue Ceremony for the Chien-Shiung Wu Commemorative Forever® Stamp with @USPS on Thurs…
Reading the news on @arxiv. Strongly correlated electrons is my category of choice. I'm really glad chemistry finally embraced preprints too now that @ChemRxiv is a thing. #preprints https://t.co/rTtUAqDZGA
Of course I am a postdoc on a precarious contract about to end, so here's the other news I try to keep an eye on daily. I hope I'm still hireable! @jobsacuk #postdocs #AcademicChatter https://t.co/oNs3hxlmfo
RT @PhysicsNews: Tomorrow is International Day of Women & Girls in Science, and to celebrate, we will be retweeting your #IAmAPhysicist sel…
Magnetism in solids is a bit tricky to explain. We all learn in school that an electric current going round and round in a loop will induce a magnetic moment. This is how electromagnets work. We can use this analogy for electrons and cations in solids. #magnetism #miracles https://t.co/ZioUxIEFPM
Electrons have a negative charge, and so they also have a magnetic moment when they go round and round. Electrons have an inherent magnetic moment called spin, which is due them spinning around their axis (kind of). They also have a moment related to their orbital in an ion. https://t.co/sDjTq19gES
Magnetism of filled orbitals and electron shells cancels out. Magnetism in solids requires unpaired electrons! These are found in transition metals such as iron and lanthanides such as neodymium. Magnetic moment of a cation is related to the number of unpaired electrons it has.
We can treat magnetic cations as tiny magnets inside a solid. Magnetic properties of a material are defined by what the cation is, how they are arranged and how they interact with each other. The interactions cannot be described without quantum mechanics, but that's ok.
Quantum magnetism occurs, when this "oh they're just tiny magnets" analogy breaks down. This occurs when the cation only has one unpaired electron, which can then start to misbehave due to quantum mechanics and do all sorts of weird things. https://t.co/bB9tk7YPrY
@goldclusters Excellent question! The idea here is that if you have a localized electron on a d orbital and you put another electron on the same orbital, the presence of the first electron will strongly affect the second one and you have to take this electron correlation into account.
@goldclusters This correlation is a really complex many-body problem. When the electrons are delocalized, they are far away from each other and can be modeled like a non-interacting free electron gas. The electrons don't spend much time close to each other, and this approximation is alright.
Magnetic interactions try to align spins (moments) in a material either parallel (ferro-) or antiparallel (antiferromagnetic) to each other. When all the interactions between spins cannot be satisfied at the same time, the material is frustrated. https://t.co/MHhVoNJemz
Frustration occurs when the spins are arranged in certain shapes such as triangles, tetrahedrons or squares. It can stop materials from magnetically ordering (all spins have a fixed direction). Instead, the spins can form collective quantum entangled states with weird properties.
Anderson proposed a quantum spin liquid state on a triangular lattice of spins (moments). In this state, the spins do not freeze even at absolute zero. Instead, they pair up to form valence bonds. The QSL is a superposition of all the different ways to cover the lattice in bonds. https://t.co/d0psDda6UU
QSLs are quantum states with a massive number of entangled spins. They're very weird. If given some energy, the QSL state can have excitations that carry only spin instead of both spin and charge like electrons. QSLs could have applications in a new type of quantum computer.
A number of excellent QSL candidate materials are known. Herbertsmithite ZnCu3(OH)6Cl2 is a QSL candidate with a Kagome lattice of Cu2+ spins (see the Kagome basket below). There is no single "smoking gun" experiment for identifying a QSL, which makes it all quite difficult. https://t.co/k1UvR8BUbS
This review by Leon Balents is an excellent introduction to the field of quantum spin liquids. https://t.co/6Mq3rVEQtf
[admin] "Strange World of Quantum Materials" Extended podcast conversation with the amazing @OHJMustonen is out now! https://t.co/RKBdCQCqLR
Anderson proposed a quantum spin liquid state also on the square lattice, which is found in high-Tc superconductors. For over 30 years there were no QSL candidates on the square, until me and coworkers discovered one. https://t.co/dDA1GMCrmu
This was a collaboration between my PhD supervisor Maarit Karppinen's group at @AaltoUniversity, physicists in Brazil, Germany and Japan and muon and neutron scientists at @psich_en and @isisneutronmuon. Thank you so much everyone!
Two different antiferromagnetic arrangements of spins are possible on the square. The one observed depends on the interactions in a material. However, if the interactions are just right between these states, a QSL might be found. https://t.co/zWLltQG1ex
We found that two almost identical copper compounds have these different magnetic states, with the only difference being a Te6+ (d10) instead of a W6+ (d0) cation. I had the simple idea of let's just mix the two and see what happens. And it worked!
This mixed compound Sr2CuTe0.5W0.5O6 has many of the properties expected of a QSL. Most importantly it does not magnetically order down to 19 mK despite antiferromagnetic interactions. This material could be a QSL or a QSL-like random singlet state.
Measuring this compound at @psich_en was probably the coolest moment in my (brief) scientific career. We had no idea what would happen going in, and I was just so excited to find out it might be a QSL. And then we walked to a nearby village for a lovely dinner. https://t.co/T3vhEvlZes
RT @ProfRachelGaN: Oh my goodness! I'm on the front page of the @Cambridge_Uni webpages today for @WomenScienceDay! If you'd like to read…
RT @CaboAntonija: It's #WomenInScience day! #iamaphysicist using synchrotrons and lasers to study electronic structure of 2D and topologica…
RT @surface_matters: It's that time of the year: #WomenScienceDay! #IAmAPhysicist and I study atomically thin films of materials & their pr…
RT @girl_in_physics: I’m a Plasma Physics PhD student from @imperialcollege but based @SLAClab looking at what the inner workings of planet…
RT @HIgalaxies: On @WomenScienceDay I am analysing ASKAP radio data of galaxies, supernovae, ORCs, and cluster relics to study the many phy…
RT @Kathryn_Coldham: As a @Bruneluni PhD student, I analyse data recorded by the @CMSExperiment at @CERN to find out if one of the ways pre…
RT @Amie_Science: I'm no longer using my physics as much as these awesome ladies, but #IAmAPhysicist and use my physics background to help…
RT @ejwsolutions: I loved my medical physics research but now I support researchers (including physicists!). Pic is me in action #IAmAPhysi…
RT @YvonneBecherini: . #IAmAPhysicist Teaching Astrophysics, Cosmic-Ray Physics & Experimental Cosmology, constructing and operating partic…
RT @cayfor: #IAmAPhysicist I make sure x-ray equipment gives you optimal image quality using minimal radiation dose #WomenInScience #csowis…
RT @freyablekman: Today is #WomenInScienceDay and this woman in science will be teaching first-year bachelor physics (as is usual on Thursd…
RT @DouganGroup: Today is International Day of Women & Girls in Science. #IAmAPhysicist exploring hierarchical biomechanics, single molecu…
RT @helen_hm11: #IAmAPhysicist I am a solar scientist. I work with colleagues to show girls that science IS for them too. Photo taken last…
RT @JGaladePablo: Today is International Day of Women & Girls in Science! I am a research fellow at the University of Tokyo and I use femp…
RT @HyperboIeva: I didn’t even know about this but what a brilliant way to find inspiring people! It’s #WomenScienceDay and #IAmAPhysicist…
RT @aineclareob: #IAmAPhysicist doing my PhD at @UofGGES I crush, dissolve, and zap rocks from Mars to search for complex organic molecule…
RT @anulikesstars: #IAmAPhysicist using my knowledge and skills to help ensure that people use science for good, to make space safer, and t…
RT @sadafakbarsadaf: #IAmAPhysicist I work with semiconductor for spintronics applications:Thin films and nanoparticles #WomenInScience htt…
RT @DrNicSwann: Now the UK contact for @pascoscientific, I work @SciChemEdu helping educators source reliable lab kit and help them get con…
RT @CeriBrenner: Good morning 🇬🇧 good evening 🇦🇺 Happy #WomenInScience day! Here's a special throwback. I first visited the @ANSTO Centre f…
RT @slyardley: #IAmAPhysicist who is trying to predict the arrival of energetic particles and eruptions from the Sun by studying their sour…
RT @nicoladkelly: #IAmAPhysicist studying magnetism in lanthanide compounds using SQUIDs and neutrons. And yes, those are goats in trees on…
RT @catherineregan0: It is International Day of Women and Girls in Science! I'm proud to say #IAmAPhysicist studying the plasma environment…
RT @RESC_TU_Dublin: #IAmAPhysicist working on new methods for #cancer detection and cancer treatment using #optical #spectroscopy. Happy #W…
RT @Emmanigma: I’m an astrophysicist and science communicator working to make physics accessible to everyone #IAmAPhysicist #WomenInScience…
RT @oliviakeenan1: #IAmAPhysicist working in Outreach and Public Engagement to remove barriers to physics for those for underrepresented gr…
RT @astrogreek: I’m Zoe! I’m a 1st year PhD in astrophysics researching supernovae cosmology & a lifelong aspiring astronaut! It’s the priv…
RT @JoFeanelwa: #IAmAMaterialsScientist and on #InternationalDayOfWomenInScience I have just eliminated another possibility for what the my…
RT @i_jayas: PSA on Intl Day of Women & Girls in Science: Women in Science include Black women, women with disabilities, trans women, quee…
RT @DrRachelEyre: I’m not sure how I feel about #internationaldayofwomenansgirlsinscience this year. The fact that you can go from prize wi…
RT @JanSkakle: #IAmAPhysicist at the University of Aberdeen for lots of years, now a Professor, work in Solid State (especially perovskite…
RT @newscientist: It's International Day of Women and Girls in Science - so let's celebrate some of our scientific heroes. #womeninscience…
RT @MahaJabir2: Happy #WomenInScienceDay Ladies 😌💅 #AcademicChatter https://t.co/0DhlLrmDYG
Neutrons are subatomic particles that help keep the cores of atoms together. But they are also waves! This means we can do science with neutron beams like we would with beams of light. Neutron scattering is a powerful technique for investigating materials. #waveparticleduality https://t.co/utFxkYWgdg
Neutrons can be used to measure the structure of solids at the atomic level and dynamics like lattice vibrations. Neutrons penetrate deep into materials. This means we can use neutrons to study the strains and stresses in large objects like turbine blades.
Most importantly for me: neutrons have a magnetic moment. This makes them very useful for studying magnetic materials, since they are scattered by the spins (magnetic moments) in materials unlike X-rays. #magnetism #neutrons
There are two ways to make neutrons. In nuclear fission, the nucleus of a heavy element splits into lighter ones while releasing energy and neutrons. The other is spallation: a proton travelling almost at the speed of light hits a nucleus shooting neutrons all over. #neutrons https://t.co/NfaO2GH7t8
The need for a nuclear reactor or a particle accelerator means neutron science can only be done at large central facilities. Reactor sources include @ILLGrenoble and @ANSTO while spallation sources include @isisneutronmuon, @ORNLNeutrons, @psich_en and @essneutron. #neutrons
I went on a trip to a nuclear power plant when I was a kid. I was so disappointed we only got to see the visitor center! I finally got to go inside the actual reactor building at @ILLGrenoble , which was really cool. #neutrons https://t.co/rEcZseQVNo
Understanding how the atomic level structure of materials affects their properties is one of the cornerstones of materials science. Neutron diffraction is an excellent method to determine that atomic and crystal structure. #neutrons #diffraction https://t.co/4d1grBNqdo
Most solids are made of tiny crystals with all the atoms arranged in a repeating pattern. Neutrons (or X-rays, or electrons) only scatter from crystals at certain allowed angles depending on their crystal structure. This is called diffraction. #braggslaw https://t.co/FzFpYkX9Hh
Neutron diffraction makes it possible to accurately determine the positions of light atoms like lithium and oxygen, which is difficult with X-rays. Hydrogen is still problematic as it increases the background, and it is often replaced with deuterium for neutron experiments.
In magnetic materials, the directions of the spins (magnetic moments) of all the magnetic ions can be determined with neutrons. This is possible, because neutrons have their own spin and are scattered by the magnetic ions. #neutrons #magnetism https://t.co/gGNmpNl42z
Inelastic neutron scattering is a technique, where the neutrons lose energy as they scatter from the material. This makes it possible to study excitations such as lattice vibrations (phonons) and spin waves, which are tiny distortions of the ordered magnetic structure. #neutrons https://t.co/vCC3Re5rfD
Lattice vibrations play an important role in heat conduction, electric transport and superconductivity. Investigating the spin waves of a magnetic material make it possible to determine its magnetic interactions.
Our recent paper on magnetic double perovskites highlights some neutron scattering techniques. We used neutron diffraction to solve the magnetic structure and inelastic neutron scattering to investigate magnetic interactions. @isisneutronmuon @msesheffield https://t.co/SteTJ0TcCJ
Inelastic neutron scattering data just looks cool. Each yellow or light blue point corresponds to a neutron exciting a spin wave. Measured data on the left, simulation on the right. https://t.co/NUZedpcrUS
These experiments allowed us to formulate simple rules for magnetism in double perovskites that have a nonmagnetic d10 or d0 cation on one of the B-sites. d10 cations will lead to Type 1 magnetic order and d0 cations will lead to Type 2 order. #perovskites https://t.co/mBtGqmcVoF
This week I'm running an experiment at the D7 polarized neutron diffractometer at @ILLGrenoble . Polarization analysis allows the separation of the structural and magnetic scattering from each other. This can be used to study dynamic magnetic states like spin liquids. #neutrons https://t.co/eBtUxS1fRT
I'm very sad this is a remote experiment as I love Grenoble. Beamtime is my favorite part of the job, and it's just not the same when you're sitting at home. That said, many thanks to all the dedicated instrument scientists who make these experiments possible at all! #beamtime
The real cost of beamtime at a neutron facility is of the order of £20 000 a day. This means we always need to apply for beamtime even though we don't directly pay for it. The proposals are ranked by a scientific panel, and the best ones get beamtime. #neutrons #beamtime https://t.co/Bh6zKw5EXp
A beamtime proposal will include the scientific background including what you already know about your sample, an overview of the proposed experiment and what it will tell you, and the reason why neutrons are the only/best way to find out.
If you're interested in doing an experiment at a neutron facility, instrument scientists are the best people to contact. They will be able to tell you if your proposed experiment is sensible and the best instrument for it. Instrument scientists are awesome! https://t.co/OYytsnMfes
RT @jesswade: okay, this is really happening! i wrote a children’s book about materials and nanoscience. the illustrations are by the wonde…
What's the best way to learn to do neutron scattering? I would highly recommend neutron training schools run by neutron facilities and universities. They're a great opportunity to learn the fundamentals, meet instrument scientists and sometimes you even get to do experiments! https://t.co/ic5JF1whX6
RT @jkj_2309: @RealSci_Nano Also talk to us #neutron scatterers 😉 we are super excited about what we do and love talking about it and expla…
RT @AnnaParadowska1: @RealSci_Nano If it is possible to enhance your research with neutrons we will help you make it happen! Contact exper…
RT @i_jayas: I am a PI and I HAVE zero tolerance for toxic behaviors in my team. Highly recommend setting up a code of conduct for the grou…
Muons are short-lived elementary particles that are a bit like heavy electrons. They are produced when cosmic rays hit the atmosphere and in particle accelerators. Muons are a highly sensitive local probe of magnetism. Muon sources: @isisneutronmuon @psich_en @TRIUMFLab @J_PARC https://t.co/78OF7dY6Ia
Muons have a fun property: their magnetic moment points in the opposite direction of where they're going. We can use this spin polarization in muon spectroscopy to study magnetic materials, superconductors and ionic conductivity in batteries. #muons #musr https://t.co/dRsu5VkW2j
In muon spectroscopy, positive muons are implanted in the sample. The muon spin will start to rotate in the internal magnetic field. The muon quickly decays into a positron, which flys mainly in the direction of the muon spin at time of decay. The positrons then are measured. https://t.co/IXIGOGsBDQ
Where the positrons are going tells us what the muon spin is doing as function of time, which in turn gives us information on the properties of the material. Muon spectroscopy is related to NMR, but it works even in zero magnetic field.
Muon spectroscopy can be used to study both both static and dynamic magnetism. It's great for quantum spin liquids, which have no "smoking gun" experimental signature. But muons allow us to rule out more common states such as magnetic order or a spin! #muons #spinliquids https://t.co/dQFKIZ6Qx8
Oops, rule out a spin glass state I mean.
RT @isisneutronmuon: Roses are red, Violets are blue, You may know about us, But, what do we do? We produce neutrons, In target station 2,…
RT @isisneutronmuon: ... Even before you arrive, Our staff play a part, Keeping everything running, So you’re ready to start. Then you b…
RT @JannaGoebel: Roses are red Violets are blue I have more of a comment than a question for you #AcademicValentines
RT @AcademicsSay: Track changes are red I am so blue Why am I not enough For Reviewer 2 #AcademicValentine
RT @AcademicChatter: Roses are red Violets are blue [Purchase full-text access for $59.00] #AcademicValentines
Happy Valentine's day everyone and thank you for this opportunity! It's been a fun week! You can follow me at @OHJMustonen. If you would like to take over this account for a week, please fill in the Google form below. https://t.co/OzcpXsyuHF
[admin] Thank you @OHJMustonen for a wonderful week of science and taking us around the strange world of quantum materials. Do give Otto a follow! Podcasts where Otto speaks about his science and more - Short - https://t.co/jv8f4IBWkS Long - https://t.co/RKBdCQCqLR https://t.co/tO34aOYctK
Anna Piras
[admin] "Puppeteer Playing with 2D Materials" Please welcome @AnnaPiras19 for a week of ubercool science and listen to the podcast to know what is coming your way 👇 https://t.co/C3PdaUEMOu
Hi everyone! My name is Anna Piras (@AnnaPiras19) and until the 28th of Febraury I will take over this account to talk about myself, computational chemistry and other cool nanoscience things.
Program of the take-over: - Sat (20/02): introduction on myself and my research - Sun (21/02): my scientific career - Mon (22/02): outside science and research - Tue (23/02): what is computational chemistry? - Wed (24/02): the magical world of graphene 1/2 https://t.co/pJBd4SYkbT
- Thu (25/02): rational design of materials - Fri (26/02): applications of 2D materials - Sat (27/02): various, Q&A - Sun (28/02): future perspectives for myself and my field 2/2
About myself: I am a 2nd year PhD student in Computational Chemistry, studying in Heidelberg, Germany. I work in the amazing @HITStudies in the Computational Carbon Chemistry group (@grynova_CCC). https://t.co/YRtx0vpMhw
About my PhD: I use computer simulations to understand the role that weak interactions play in material science, molecular electronics and chemistry. 1/3 https://t.co/QIGiE8gAFT
It is a quite large field, so I am able to explore a lot of different phenomena and systems. But my main interests are graphene and other 2D-materials. 2/3
Simulating how molecules interact with these materials we hope to find interesting trends and behaviours, that allow us to understand how to exploit 2D-materials in new and more efficient ways. 3/3
On Sunday no work or science, so I enjoyed the amazing weather in Heidelberg with a nice hike. https://t.co/qULhIF4swT
Even during the week I try to go for a walk (or run) in the nature at least once a day, to rest my mind and find new energy. https://t.co/ujrKSFp0In
My scientific career pt I: How did I decide to become a scientist? Until I was 19 I lived near Oristano, a small city in Sardinia (Italy). 1/5 https://t.co/Q7kHLVG2C2
During my first years of elementary and middle school I wanted to become an archeologist and I did not care a lot about science, but I enjoyed math. 2/5
When I was 12 years old we started talking about chemistry at school and I really didn't like it. I struggled a lot to understand the beauty and utility of it. 3/5
At that point my mother, librarian, decided that a book could be a good solution for my chemical problems and she got me "Uncle Tungsten - Memories of a chemical boyhood" by Oliver Sacks. That book helped me see chemistry as the beautiful and amazing science it is. 4/5 https://t.co/pyRwBgQfS1
After that it become quite clear that I would have been a chemist and I continued reading about it during all my high school years. I had a periodic table all the time with me. The future was decided! 5/5
@JoFeanelwa I envied the protagonist so much! He was free of making experiments, visit all London's museums..
My scientific career pt II: I obtained my bachelor degree in Chemistry and Materials Chemistry at @UniboMagazine. My bachelor thesis was a spectroscopic + computational study of the structure of an amino-alcohol (https://t.co/uWwHyQkL3A). 1/3
I stayed in Bologna for my master. For my thesis I started working on computational graphene chemistry, studying the carbo-catalytic reduction of a sugar. 2/3
I enjoyed that project so much that I decided to do a PhD in that field and I was very happy when I found my current position, as a PhD in Computational Carbon Chemistry. 3/3
What is computational chemistry? We can say that is the use of computer simulations (in silico experiments) to solve chemical problems. But this actually covers a lot of different fields and applications, from drug design to astrochemistry. 1/5 https://t.co/LsGEIijr6N
Nowadays it is mainly used to give guidelines to scientists performing experiments, speeding up the research process. And, with the development of software and hardware, computational sciences are becoming more important. 2/5
The efficiency and low cost of computer simulations makes them the perfect tool to predict properties and behaviour of different substances and then proceed to test non-virtually just the ones with a specific profile. 3/5
I apply these concepts to understand how different 2D-materials can be exploited for analysis, electronics or catalysis. I still rely on good experimental data to check the accuracy of my simulations and to reproduce, as much as possible, the real-world conditions. 4/5
Of course still a lot of progress is needed in computational chemistry. We work with approximations and it is impossible to reproduce everything that happens. We can just try to find better models and methods, and improve the efficiency of the algorithms used. 5/5
[admin] "Puppeteer Playing with 2D Materials" Extended conversation with the amazing @AnnaPiras19 is out now 👇🎙️ https://t.co/TrSW07VXSG
Graphene: what is it and how was it discovered? #graphene is a 2D material composed only by carbon atoms. These atoms are disposed in a hexagonal lattice, like a honeycomb. It is an extremely robust, conductive material, with a lot of possible applications (see next tweets). 1/3 https://t.co/76yyHICc4J
Graphene is obtained by graphite (the main ingredient of pencils leads). Graphite is composed by a lot of super-thin (one atom thin) layers of carbon sheets. Each one of these is a graphene sheet. 2/3 https://t.co/kXmJLRDu9m
The first report of graphene was just in 2004, by professors Geim and Novoselov. They discovered the secret amazing material hidden in the underestimated graphite. If you want to know more about the discovery and the discoverers: https://t.co/ohhr06nsZS 3/3
Pristine graphene, as the perfect infinite hexagonal lattice we are used to see, is an ideal material. What it is obtained in a reality is a material containing defect, holes and impurities. The ideal graphene does not exist but there are bright sides. 1/4 https://t.co/GhxYv0ZbA0
The possibility of changing the structure and the composition of graphene during the synthesis allows us to obtain a whole family of compounds: graphene-based materials (GBMs). 2/4
We have then a big pool of 2D materials to exploit and study! While some defects or functionalities are randomly introduced during the production of graphene, some of them can be introduced voluntarily, using different synthetic conditions. 3/4
Some of these "defects" are quite useful. For example, it was discovered that, while pristine graphene is almost useless in catalysis (not very reactive), a simple oxidation of it allows to unlock good catalytic performances. 4/4
@goldclusters Partially yes but also the ways to obtain graphene are responsible for it. The conditions used introduce new defects.. like if you form it on a metal surface some metal atoms "enter" in the lattice or if you exfoliate graphite holes or deformations can be produced
Using computational chemistry is it possible to study the properties of molecules, understanding the mechanism of reactions and design drugs or catalysts. But it also possible to design a material. How can we do it? 1/5
1)think about which kind of material we want, both composition (graphene derivative? inorganic material?..) and function (adsorbant? sensor? ..). At that point it is necessary to check the literature to see how different material perform for the desired task. 2/5
At that point it starts the difficult part: we need to find some property we can calculate or simulate and try to see if there is a relationship between the performance shown by the material and the computed property. 3/5
If you find that the relationship exist then we can "design" a material, compute the property and from that predict how well it will perform. If we don't find a relationship probably the chosen property has no effect on the performance and we should try others. 4/5
There are some challenges: use accurate methods to simulate the material and compute the property, the need to consider the different experimental conditions in which our data were measured, the performance probably depends on more than a single property.. 5/5
Graphene and its derivatives are the most famous between 2D materials. These materials are very interesting because: - high surface/volume ratio - usually high mechanical robustness - particular optical and electrical properties - tunability of structure and properties.
2D materials can be used, exploiting their particular properties for a lot of different applications, from nanoelectronics to water depuration. 1/4 https://t.co/aBCLEK6ydu
My interest in mainly in environmental applications. As I said 2D materials have an high surface/volume ratio, so if they interact with contaminants they can be used as filters for water or air. 2/4
Many 2D materials (like graphene derivatives) are semiconductors and they can be used as sensors, to determine the quantity of contaminants in a sample. The molecules will get adsorbed and this will cause a measurable change in the properties of the sensing material. 3/4
There are a lot of other amazing applications for 2D materials. They have been used to obtain highly efficient solar cells, they have been used in photothermal therapy and to enhance the mechanical properties of hydrogels. 4/4
Today is my last day of take-over and I want to talk about the future of my field. The future for computational chemistry looks exciting and full of challenges and possibilities. New developments in computer science are giving scientists amazing tools! 1/4 #compchem https://t.co/ocsepZS0sz
Machine learning is one of the most hyped and promising tools. The possibility for a machine to find trend and properties in large datasets of molecules, with the aim to predict and design new systems is incredible and almost scary. (https://t.co/P2NWFom1Ix) 2/4 #machinelearning
The development of super efficient computational algorithms has also offered the possibility of analysis large numbers of systems, causing the building of large databases, so the choice of the studied set is becoming less difficult, because it is possible to not be selective. 3/4
The role of the computational chemist is clearly changing and developing. It is still important for chemist to invest time and research into developing computational methods, to couple the performance of machines with the experience and instinct of chemists. 4/4
This is the end of my take-over. I'm really glad for this opportunity to share my research and my ideas! If you are interested in computational chemistry and 2D materials follow me at @AnnaPiras19
[admin] Thank you Anna for a wonderful week of nanoscience! Do give @AnnaPiras19 a follow. Listen to the podcasts to know more about Anna's research Short - https://t.co/C3PdaUEMOu Long - https://t.co/TrSW07VXSG https://t.co/aSaAocUU5G
Laia Delgado Callico
[admin "The Curious Case of Melting at the Nanoscale" Please welcome @LaiaDelCa for a week of uber cool science and listen to the podcast 👇 to know what is coming your way this week! https://t.co/VpJCydBKVX
RT @realscientists: [admin] "The Curious Case of Melting at the Nanoscale" Please welcome @LaiaDelCa for a week of uber cool science on @…
Hello! I am Laia Delgado Callico, @LaiaDelCa here. I am very happy to be taking over the @RealSci_Nano account this week https://t.co/YByOpqiJB1
I am a PhD student at King’s College London @KingsCollegeLon, in the Physics department @KCL_Physics. The title I chose for my podcast “The Curious Case of Melting at the Nanoscale” would be a great title for my thesis too https://t.co/7USVnVmCqo
I was born in Barcelona, surrounded by the sea and the sun, with delicious food and breath-taking architecture. https://t.co/KkpKBi9BvQ
Mentioning you are from Barcelona is always a great icebreaker, people usually comment ‘It’s my favourite city’, ‘It's so beautiful’, ‘I'd like to visit it’. Which is an honour for me😊
As a child I loved reading, I'd read a book a day. The public library was one of my favourite places https://t.co/auYskDelSC
RT @LondonNanotech: Laia a PhD student is a member of the #LCN from @KCL_Physics she is taking over the @RealSci_Nano account this week. ht…
In high school, thanks to my amazing teacher, I felt in love with Chemistry. She was a Chemist and she was super passionate about it.
When I had to choose what to study at university, I was not sure about what degree I wanted to pick. I liked (too) many things. I was not the kind of person who knew what they wanted to be since childhood. https://t.co/beAQLi7S2J
Maybe it's because no one else in my family is a scientist. If you are a scientist, is anyone in your family a scientist too?
But yes, I did end up choosing Chemistry as a degree, I really enjoyed chemistry in high school, and I enjoyed it at university. I studied at the University of Barcelona @UniBarcelona
So, I started my Chemistry degree. Four years learning things like how to draw hexagons and that if you stain your skin with nitric acid it will become yellow, what we called Simpsonitis https://t.co/upwiBc0rnV
During the last year I did a research stay at Imperial College London @impchemistry thanks to an Erasmus grant @EUErasmusPlus. I was lucky this happened 5 years ago, before Brexit, now this is no longer possible.
@impchemistry @EUErasmusPlus I stayed in London for my Master, where I moved to King's College London to study Molecular Biophysics. From there, I moved to the Physics department for my PhD https://t.co/vPEPV6c9gf
@impchemistry @EUErasmusPlus Here I am now, in the last year of my PhD. My research is computational, I use methods like Molecular Dynamics and Density Functional Theory to model clusters and nanoparticles.
During this week I will talk more about my research and the cool properties of matter at the nanoscale https://t.co/GuTdJeWU06
My research is computational. Does computational research imply coding? Not necessarily. https://t.co/j9BxftYa3d
I think this is a misconception in the field. Could I have done the same research in my PhD without writing a single line of code? Yes Have I written any line of code? Yes, many. https://t.co/pNBMjtkwqJ
The codes I use are already written, so I just have to ‘run’ them. On the other hand, I have had the chance to contribute to our group code, written by current and past members of the group.
I use daily scripts for inputs and postprocessing, which make my life easier, but I’m a rebel and I don’t use Python, R or Matlab for figures, I use gnuplot. Any other gnuplot user here?
Today is the #RSCPoster day, I am looking forward to having my timeline filled with great posters. I am also participating with my own #RSCNano poster, check out these hashtags during the next 24h 👀
RT @RealSci_Nano: I use daily scripts for inputs and postprocessing, which make my life easier, but I’m a rebel and I don’t use Python, R o…
@gnuplot5 https://t.co/qFAD7ZzNiM
It is great to see so much creativity. An online conference and on twitter is the best place to break the rules to create an engaging poster
RT @LaiaDelCa: "A universal signature in the melting of metallic nanoparticles" A Twitter themed Poster for a Twitter Poster Conference…
This is the first time I participate in the #RSCPoster, because I just joined Twitter three months ago. These kind of events are definitely the reason why I decided to open my academic twitter account
[admin] "The Curious Case of Melting at the Nanoscale" Extended conversation with the amazing @LaiaDelCa is out now! 👇 https://t.co/5zIO8xebRb
RT @RealSci_Nano: [admin] "The Curious Case of Melting at the Nanoscale" Extended conversation with the amazing @LaiaDelCa is out now! 👇…
RT @realscientists: [admin] "The Curious Case of Melting at the Nanoscale" Extended conversation with the amazing @RealSci_Nano curator @…
For my research I use high performance computers (HPCs), I don’t run my calculations locally in my laptop (I’m sure my laptop is very happy about this) https://t.co/joV2F8NliU
HPCs are ranked in Tiers according to how powerful they are and their span (international, national, regional, or institutional). https://t.co/FBpJYem4l7
I use the HPCs at King’s College London, one is called Gravity (the one for the physics department) and the other one is called Rosalind, after our very own Rosalind Franklin. https://t.co/1mXNZUPU60
Shout out from here to the IT service @KingsITsystems. They have always been super helpful and efficient. I once had a Windows blue screen error on a Saturday night at 23:52 and it was solved by 00:06 https://t.co/NWbIl95BL0
I also use the UK national HPC, Archer @ARCHER2_HPC which is brand new #HelloARCHER2
and the London HPC: Young, named after Thomas Young @tyc_london https://t.co/0a8tXsFydr
High Performance Computers seem safe and robust, but last year, there was a week filled with panic for computational researchers 🧵 1/8 https://t.co/2xLBzvleNb
Last May, several supercomputers across Europe were hacked. The systems had to be shut down to prevent further attacks. For several days we couldn’t access our data. 2/8
We didn’t know what was going on. All the information we had was: we are investigating an attack and precautionarily preventing access. 3/8 https://t.co/we4xTVNacw
This impacted the research on the COVID-19 vaccine, since researchers were using these computers for their simulations. 4/8
At the beginning, we didn’t know what the damages of this attack would be. Would research data get lost? How long would the system be down for? 5/8
We didn’t know who attacked the HPCs or what were their motivations. Was it people trying to steal data from the vaccine research? There were all kind of rumours among scientists. 6/8
Turns out, the reason behind the attack was for cryptocurrency mining. 7/8 https://t.co/LzAc8TxR32
Fortunately, no data was lost and to prevent this from happening again, all passwords were reset and now, after increasing their security level, we require both a password and a passphrase to access the computers. 8/8 https://t.co/85Lt0vUKpz
RT @MySci_PK: The team behind the amazing @RealSci_Nano account is *always* looking for reasons to celebrate. 🎉 You can help reach the 2k…
#FollowFriday 1. Introduce yourself 2. Describe your research with three emojis 3. Guess other people's #AcademicChatter #PhDLife
I start: https://t.co/4481wasvOr
@carlosromvil @LaiaDelCa https://t.co/TBiGqXIrNj
@carlosromvil You are either trying to find a way to break the space-time continuum and get rich with your idea, or you study fluidic properties of noble metal materials. I'm pretty sure it's the first one 🤔
@carlosromvil I like cool metal stuff https://t.co/dakb54PV3v
RT @LaiaDelCa: Do you ever feel that every paper about nanoparticles mentions the same clichés over and over again Now have fun while read…
@HosseinMovla Computational study of solar cell batteries?
Computational research goes better with experimental results. As a purely computational group, we rely on experimentalists to provide their data for comparison. https://t.co/hj8QzsC6Bm
A common way is comparing vibrational spectra. But my clusters are metallic and the metal-metal interaction falls in the Far infrared spectrum, which is not easy to observe experimentally.
You need a laser that has: ✅tunable wavelength ✅wavelenght at the Far IR ✅powerful enough A Free-electron laser ticks all the boxes
Like the one in Nijmegen (The Netherlands) at Radboud University. Its name is FELIX. https://t.co/8um9uXg5qO
Obtaining the IR spectrum computationally is relatively easy, all you need is a Frequency calculation. https://t.co/5VSNxlAkLS
Another way to compare experimental data with theoretical results is using mass spectrometry.
After photofragmentation experiments, we can obtain a mass spectrum informing us about the relative stability of our clusters. A high intensity in the spectra indicates a high relative stability of these clusters.
Then we calculate dissociation energies using Density Functional Theory. A higher dissociation energy will indicate that the cluster is more stable.
This way we can find which clusters are more stable, what we call: magic numbers and magic clusters. https://t.co/DyV6AWdZ6H
I did this for this paper, in collaboration with @KU_Leuven https://t.co/b870H0WY1t
and I discussed the paper in this thread https://t.co/BtDnwWSBUF
RT @LaiaDelCa: Research group members as The Office characters, a thread: Michael Scott - the PI, pretends to work but doesn't get anythin…
Today is my last day on this account, follow me on @LaiaDelCa for more nano science and (bad) scientific jokes https://t.co/I1jsTwrPAc
We also published this paper based only on computational results. https://t.co/lZm2dGrVDZ
We developed a new method to identify melting temperatures based on the nanoparticles structures, we hope this can be proved experimentally using X-ray diffraction spectra. Any experimentalist is welcomed to try it 😊 https://t.co/Qu9ZYEiTk2
I discussed this paper in this thread: https://t.co/Mj0U3IPTs8
[admin] Thank you Laia for a wonderful week of science. Do give @LaiaDelCa a follow. Listen to the podcasts to know more about Laia and her science. Short - https://t.co/VpJCydBKVX Long - https://t.co/5zIO8xebRb https://t.co/kMq4nbE2ks
[admin] "Phase-change materials – From DVDs to Tunable Photonics" Please welcome this week's curator - @nanouschi and listen to the podcast to know what is coming your way this week! 👇🎙️ https://t.co/1vI0nH9TR1
Thanks to @LaiaDelCa for her great insights during the last week. Today, I'll start to curate this account. I'm @nanouschi, a materials scientist currently working @ETH_en & transferring to @TUeindhoven in a few weeks. I'm excited to read your comments & Qs throughout the week.
Ann-Katrin Michel
[admin] "Phase-change materials – From DVDs to Tunable Photonics" Please welcome this week's curator - @nanouschi and listen to the podcast to know what is coming your way this week! 👇🎙️ https://t.co/1vI0nH9TR1
Thanks to @LaiaDelCa for her great insights during the last week. Today, I'll start to curate this account. I'm @nanouschi, a materials scientist currently working @ETH_en & transferring to @TUeindhoven in a few weeks. I'm excited to read your comments & Qs throughout the week.
Since it's #IWD2021 I dedicate this 1st day to some outstanding female scientists. I've been supervised by some, collaborated w/ others, or sought out for their mentoring deliberately. I also worked w/ many other great scientists who I value & respect but today should be about ♀️
The first female PI I worked w/ was @DeliaMilliron. She gave me the amazing opportunity to join her group @molecularfndry for my MSc thesis. An unforgettable time - I learned a lot (scientific/personally), met great people, & worked for the 1st time w/ many female scientists. https://t.co/PqqHDx9CUz
During my PhD I met @EPFL_altug_lab & was blown away by her amazing science & her wonderful talks. Since then I'm following her work & am happy about every new achievement of hers (which are many). She's a true role model to me & I'm glad young students can be inspired by her. https://t.co/P3dLU1aWk2
As a postdoc @ETH_en I sometimes felt stuck & missed orientation. I'm thankful that I had the opportunity to meet @UlrikeLohmann3 as a part of a mentoring program. She helped me tremendously to navigate my postdoc, apply for TT positions, & maintain my #mentalhealth. https://t.co/EAKmDuQQi8
During my postdoc @NorrisOMEL I had the pleasure to collaborate with @VanessaWood_ETH & her group. I'm beyond excited for her being now Vice President @ETH_en. Seeing such extremely gifted & driven female scientists succeed like that is truly inspiring. https://t.co/vDhhdCes0D
During the pandemic, I've been lucky to start a collaboration w/ @rachel_grange & her group. I met her as a part of @PhotonicsMeetup & don't know any1 who seems to be so full of energy & ideas. Rachel has been supporting me since we met & I cannot say how much that means to me.🙏🏻 https://t.co/3H8jOtN9Q6
@ProfArmani is another extremely inspiring #WomenInSTEM who I met @PhotonicsMeetup. I admire her for all her outreach & support for #ECRs. I rarely feel as seen & understood as in conversations w/ her. Thank you! https://t.co/1TheZbiKwj
Finally, I would like to thank @UrsiKeller While every1 knows her for her outstanding contributions to sci, I also met her as a wonderful #mentor. The exchange w/ her made me decide to accept my new pos, despite the anxiety that comes w/ moving countries & being apart from my hb. https://t.co/BRHMtsm26P
Thanks to all the other female scientists, teachers, coworkers, authors, artists, athletes, ... mums, sisters, & friends who inspire us. We need you as much as we need our male allies. Thanks to all dads, bosses, teammates, friends, ... who are there to support us. #IWD2021
Today I would like to share a bit more about my bkgd. To avoid just writing a boring resume I would like to focus on #finances as a (grad) #student 🇩🇪, #postdoc 🇨🇭, & assist. professor 🇳🇱. I hope some of you find it helpful for your decision-making process. #AcademicChatter 1/n https://t.co/8X1e8JKhxP
I was born in East 🇩🇪. My mum has a diploma in thermal managem. & my dad had a MBA from a technical college. After the fall of the Berlin Wall, my parents opened a small sales business (furniture for schools/offices). Since they hadn't much income, I qualified for BAföG. 2/n https://t.co/rklMqMOkZe
To me, this is 1 of the most amazing 🇩🇪 acts since it allows ppl from low-income fams to receive federal financial support. BAföG is a combination: 50% grant, 50% interest-free loan. When I started my BSc in Mater Sci @RWTH I received ∼ 500€/mth covering rent & groceries. 3/n https://t.co/tbGnrVBCyj
To be able to pay back the loan later on, I started in my 2nd yr to work as #teaching & #research assistant. I highly recommend working as a #TA! While it leads to a nice income (∼ 10€/hr back then), it's also a great insight into the subject & a research group. 4/n https://t.co/5LlXTI97wu
Throughout my BSc & MSc, I worked for 4 research groups. I am grateful for the opportunity to have met all these ppl, seen diff. labs, & finance my living (got paid ∼ 350-700€/mth for working 8-19 hrs/wk) with a cool job. Ask around & see if groups would need TAs! 5/n
During my MSc, I also had the luck to receive a national #scholarship (Deutschlandstipendium, 300€/mth). I was the spokesperson for a group of scholars & thus, got to meet the rector of @RWTH, Prof. Schmachtenberg (on the right). I never imagined to have such a chance. 6/n https://t.co/1B6rHnE7ZU
Being extremely lucky, I received a scholarship from @RWTH for going abroad for my MSc #thesis @molecularfndry 🇺🇸. W/o this support I would have not had the opportunity to go abroad. Reach out & check if your institution offers any financial support. It's worth it. ;) 7/n https://t.co/lHjBbWyM0f
Overall, I had an ok income as a student w/ BAföG, TA/lab jobs, & scholarships. I could focus on studying & not worry a lot about money. My dad died when I was 19 & my mum couldn't support me financially. W/o the support I mentioned, I would neither have a PhD nor be a prof. 8/n
Being a #PhD student in 🇩🇪 means you're paid by the research group - income depending on your field of studies. For us @RWTH it was like this: BIO/CHEM 50-75% contracts PHYS 66-75% ENG 100% 9/n https://t.co/wAMKll31U9
In my case, physics, 30 hrs/wk were paid work, thus I had ∼ 1.500€/mth (net). A subset of the paid hours was devoted to teaching (∼ 2ds/wk). My hb, Mech Eng PhD, got paid 100% but they all had to succeed in big research grants (xxx k€) to keep their positions. 10/n https://t.co/v3xowNhusU
I also had a side job as Academic Advisor for the MSc program in Materials Science. In this job, I worked 10 hrs/wk (all paid). Thus, I had a full income (75% PhD pos + 25% program advisor) & could pay back the remaining loan from BAföG while doing my PhD. 11/n https://t.co/Iu7rOgUvBW
Being a #postdoc @ETH_en in 🇨🇭 is financially very comfortable. It was the 1st time I really could start saving money. In the beginning, I had a 2yr #fellowship (ETH & EU) which covered a full position. For the remaining 2 yrs, I had the luck to be covered by @NorrisOMEL 12/n https://t.co/rFETL7BVLs
In May, I will transition to @TUeindhoven I still have to get used to the fact that as a #professor I'll make < 50% of what I earned as a #postdoc 🇨🇭& ≈ the same as my hb made during his PhD 🇩🇪. Since taxes & level of income are different in these countries it'll be fine. 13/n
Overall, I hope I could give you a somewhat useful overview of the financial situation for researchers in a few countries. I'm sure that it's very diff from the situation in 🇺🇸& u might consider studying in #Europe. Even internat students have to pay a bit, it's affordable. 14/n https://t.co/29sOHqoGom
Finally, I would like to thank everyone who made it possible that I could study & do research. I know I'm just one example of many academics from low-income families who were able to succeed due to the federal support @BMBF_Bund & the generosity of others. Thank you! 🙏🏻 15/15
@MolecularXtal The pictures were taken in July 2010. ;) I received the scholarship from 2009 to 2011.
@mickeykats @TUeindhoven Unfortunately not. I definitely have to adjust my lifestyle & barely put money aside.ore expensive than the shared 1. ETH also just pays extremely well. As a postdoc, I make 80% of my hb's consultant income. I def have to adjust my lifestyle & won't be able to safe as much.
@mickeykats @TUeindhoven Let's say it like that: What I can put aside every month as a postdoc at ETH right now is equal to what my net salary as an assistant professor in the Netherlands will be. So financially, the move doesn't "pay off" & that's the main reason why my hb doesn't want to join. 🤣
@mickeykats @TUeindhoven Excatly. If the salary is enough for an okay apartment & organic food, I'm mostly fine. ;) Someone told me once that a job is a lifestyle choice & we should be more aware of it. So I'm happily taking a cool job & give up some cash if needed as long as the salary is "fair". https://t.co/XCMhm2Y61m
[admin] "Phase-change materials – From DVDs to Tunable Photonics" Extended conversation with the amazing Ann Katrin Michel @nanouschi is out now! 🎙️👇 https://t.co/ogQoiUZeah
Today, I'll use this platform to share some #science w/ u. Maybe it inspires some of u 2 come up w/ new ideas or 2 collaborate. Since I heard a lecture by Prof. Wuttig @RWTH, I've been fascinated by phase-change materials & studying them for ∼10 yrs now. #AcademicTwitter 1/n https://t.co/vUVPG04gVZ
Phase-change materials exist in at least 2 structural states - 1 amorphous & 1 or more crystalline. The reversible transition can be triggered by heat, e.g., by an optical or electrical pulse. After, the material will remain in its state w/o any heat supply needed. 2/n https://t.co/eNmLGDMWWc
The structural transition is accompanied by a significant property contrast. The electrical resistivity can change by up to 5 orders of magn & the refractive index contrast can be up to 3.6 (huge!). Additionally, the density can change up to 10%. 3/n
This property contrast has been used for different applications, ranging from optical data #storage (DVD RW, Blu-Ray discs), to #memristive elements, & active #photonics. For the most part of my research, I've been focussing on the latter. 4/n
For my first #PhD project I worked on #antenna resonance tuning by using phase-change material thin films (x0 nm). Therefore, I fabricated aluminum (evap.) nanorods via e-beam #lithography & covered them with a sputtered phase-change material (e.g., Ge3Sb2Te6). 5/n https://t.co/HnifvOnboG
Changing the structural state of the phase-change material allowed for a resonance shift of the nanorod arrays. Due to the large optical contrast, the shift is quite large. However, increasing absorption in the cryst state leads to resonance damping. 6/n https://t.co/LYLRevKPk4
The aforementioned resonance tuning principle is not restricted to nanorods but can be extended to #plasmonic #absorbers, #chiral structures, etc.. 7/n https://t.co/DeBz1NHPaV
During my PhD, I also worked on the reversible switching of nanorod #metasurfaces. By collaborating with a group @Stanford, we could show that #femtosecond laser pulses allow for switching of the nanoantenna arrays shown above. 8/n https://t.co/Hx27aQ96S7
By comparing different phase-change materials, we could show that thorough knowledge of the material properties is crucial for successful sample design. Unfortunately, in many studies, prominent compounds instead of "the best 1s" are still favored. 9/n https://t.co/5d4NPVu7sG
A tricky part of revers. (optical) switching of phase-change materials is the volume extent of the structural transition. A detailed 3D analysis of our #metasurfaces showed the extent of the switched spots & the max resolution possible. 10/n https://t.co/bS5UtjFAdj
To overcome the #diffraction-limited patterning of tunable metasurfaces, we are exploring tip-induced switching. Due to Covid, we only published a theory study so far but the experiments look good & the manuscript will soon be ready for submission. 11/n https://t.co/fllNsOnYjM
Another challenge of phase-change material-based active #photonics is #bandgap absorption. Since the bandgap of the most prominent phase-change materials (GeSbTe or "GST" compounds) is 0.5-0.8 eV, photonic applications have been situated in the mid-infrared. 12/n
With phase-change material #nanoparticles, we see indications for a pronounced bandgap shift, thus allowing for tunable #photonics in the near-IR or Vis even. 13/n https://t.co/FAVZf8AnaJ
Currently, we're working on several manuscripts & I hope we'll be able to share our most recent insights regarding phase-change material nanoparticles & #nanocrystal-based #metasurfaces soon. #StayTuned 14/n https://t.co/JRen8zGa5p
I had the luck to work w/ more knowledgeable physicists, better chemists, & more creative engineers than me. And I am grateful I had #supervisors & #PIs who trusted me, let me follow my own ideas, challenged them, & encouraged me to continue. 15/n
I would like to thank everyone w/ who I've been collaborating & hope we'll have more projects together. @XinghuiYin @AndreasTittl @AndrewBPun @art_karvounis @rachel_grange @VanessaWood_ETH @abuseb @dnchigrin @AlexCHernandezO Thomas Taubner, Peter Zalden & many more 🙏🏻 16/16
After putting my 2 cents in regarding #mentors & rolemodels on Monday, #finances in #academia on Tuesday, & some #science yesterday, I would like to shine some light on #health & #selfcare today. 1/n https://t.co/wJaSPxJag3
I met many extremely driven people in academia who were often so immersed in their work or so stressed by deadlines that they forgot about any vacation, time to relax, or neglected their hobbies & friendships. Me included. 2/n
While it can seem like it works well & one can get so many things done, for many, it leads to mental or physical exhaustion later on. My personal experience was really bad & I hope by sharing it, I can help others. #mentalhealth 3/n https://t.co/YAUj1cZsR2
For the most part, I tried to "solve" the issue by trying to be "tough". I tried to pass the 11 scheduled exams in my 2nd term by studying harder & taking caffeine pills. I tried to run faster & more by ignoring pain, being tired, & taking ibuprofen after workouts. 4/n
During my undergrad, I spent a week in the hospital due to really bad gastritis. For the following yrs, I often had to stay in bed for a few days since the pain came back. So I studied in bed. #stupidity 5/n https://t.co/6iVklCmiJ2
As a PhD, I had a side job & the goal to run a #marathon. I trained a lot, cut back on sleep, won the race, & qualified for the Boston marathon in the next race. I followed this idiotic claim: No pain, no gain. Shortly after, I started to get really sick. 6/n
I had one infection after another, had to take antibiotics for mths, was sent to specialists to figure out what's wrong, & in the end got also pneumonia. I had to leave work for 3 mths & couldn't walk w/o gasping for breath, I felt like the biggest failure. 7/n
5 yrs after, I'm still not back running but I'm off inhalers since > 1yr now. And I realized some really important things for myself: First, I learned that sleep is key for me. I need 9 hrs. Maybe I won't be able to submit as many proposals as others but I won't be tired. 8/n https://t.co/0ntSwVAVXs
Second, I've been experiencing that a few smart #workouts are more impactful than many but less focussed workouts. My weightlifting PRs are from the last yr when I worked out 3x/wk instead of 5x like yrs before. And for the 1st time, I just focus on having fun working out. 9/n https://t.co/UQ9XlbGeRK
Third, I feel the benefit of making time for "just for fun" things. A nice walk or yoga outside doesn't directly lead to a new pace record, a publication, etc. but it gives the restless mind a break, relaxes my body, & brings literally some fresh air. And it's offline. ;) 10/n
I felt (& tbh still feel) guilty when reading a novel or newspaper instead of "sth scientific" #FOMO & I admire people who can get absolutely lost in their science all day. But it's me & I can't. For my sanity, I need some easy2read books, random articles, even stupid tv. 11/n
For our long-term productivity, creativity, happiness, & health, we all need to find out what we're capable of or comfortable with. We all have different starting conditions & limits. It can be a life safer to be aware of & respect them. 12/n
To my undergrad or PhD self, I would recommend not being so hard on myself. It's good to get started w/ 34 but it would have been healthier to start earlier. I would have had a happier PhD & some people around me would likely have had a better time w/ me. 13/n
So be ambitious, work hard for your goals, challenge yourself - but also realize that taking time off is a crucial part of success. Nothing will be studied or submitted if you're sick, depressed, or just extremely unhappy. @AcademicChatter n/n
Thanks to everyone who listened to the podcast or followed this account. Before I'll leave @RealSci_Nano, I would like to highlight @PhotonicsMeetup - a free virtual conference for the #photonics community, surprisingly timely irt Covid even it was planned far in advance. 1/n https://t.co/1U9iPS9d4c
I was incredibly lucky by attending the 1st edition, #POM20ja, & helping with the organization for the 2nd & 3rd round, #POM20ju & #POM21ja. I've only met a few of the organizers in person but during the last year, it felt like I became colleagues & friends w/ many. 2/n
Working from home wasn't always easy, especially with finishing projects & applying for #faculty #jobs which itself can be stressful & cause some anxiety (What's next if I cannot stay in #academia?). Thus, I'm incredibly thankful for the @PhotonicsMeetup community. 3/n
At times, it became a support network & I met great mentors. It can be a wonderful surprise to find support from people who don't "have to" offer support & seem to not gain anything themselves from it but are there & gracious w/ their time & advice. 4/n
I hope @PhotonicsMeetup will stay post-lockdown & remain an inclusive & scientifically excellent event. But it needs a lot of time & commitment - everyone is working for free. So I hope that many of you will join, be vocal about your needs & interests, & share your work. 5/n
Thanks to the @PhotonicsMeetup OGs: @ProfArmani @mickeykats @r1cc4rd0 @Orad @rachel_grange @igordownunder @sylvaingigan & the lockdown crew @JacquesCarolan @MarinaRadulaski @optrickster @sejeong85 @MImranCheema @Dana_Cialla I cannot wait for a f2f POM drink! 🍻🥂🍹 6/6 https://t.co/dP3H6oiR2w
@Ikhlasmohamed90 @BMBF_Bund I moved a bit: 🇩🇪🇺🇸🇩🇪🇨🇭🇳🇱 I think moving is crucial for academics to experience diff groups, academic systems, & research environments (incl. funding, etc.). I tried to not move too far so my partner & I could see each other every other month. Much success on your journey! :)
@sylvaingigan @PhotonicsMeetup @ProfArmani @mickeykats @r1cc4rd0 @Orad @rachel_grange @igordownunder @JacquesCarolan @MarinaRadulaski @optrickster @sejeong85 @MImranCheema @Dana_Cialla Thank you, Sylvain. So kind of you! I'll try my best... #nopressure ;)
[admin] Thank you very much Ann Katrin for a wonderful week of science. 🥳 Do give @nanouschi a follow! Podcasts featuring Ann Katrin are here - Short - https://t.co/1vI0nH9TR1 Long - https://t.co/ogQoiUZeah https://t.co/HN3lFCtROM
Robert Karsthof
[admin] "Defects Make Better Devices" Please welcome this week's curator - @RKarsthof 🥳 Listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/kEcoWsUUky
Hi everyone! I'm Robert, and I'll be tweeting from this account this week. The upcoming days will be about crystal defects in semiconductors—what they are, why they're so important and how we can make use of them to make exciting devices!
First of all, I'm curious about the follower base of this account! What's your background? This will make it easier for me to decide how much I can do into detail 😬
Also, if you clicked "other", I'd love to hear more about it in the replies :)
@chaoaretasty I'll try my best, promise!
Here is a short schedule of what I plan to tweet about this week: Monday: short intro, then I'll talk a bit about semiconductors and defects in general to clarify the most important terms.
Tuesday: There are so many ways of studying defects, both theoretically and experimentally. I'll be talking about these methods (with a focus more on the experimental side), and I'll do a lab tour to show you the most important tools we use for that!
Wednesday: I have a live experiment planned for that day. We'll be making devices that we then (hopefully) can use to detect defects in one of the materials I research, nickel oxide (NiO)!
(unfortunately, the experiment I had planned originally had to be postponed because the instrument, our ion implanter, is down at the moment. But this one will be just as exciting!)
Thursday: while defects are usually detrimental to device performance, there are also cases where they can be used to make new exciting applications and devices ("functionalization of defects"), e.g. in quantum technologies or neuromorphic computing, which I'll talk about.
Friday: a little throwback to my Ph.D. times, where I made transparent electronic devices, mostly solar cells! Defects also play a central role here. Also, there will be a Q&A session on Friday!
The weekend: non-research topics. I plan to tweet about what it is like to live and work in Norway, from an expat's perspective :)
If there is anything you'd like to ask, or have included in the schedule, just let me know :) Looking forward to the next few days!
@itsretzev Cool! Good to hear that those classes could not kill your curiosity :) Subpar (in terms of pedagogical quality) science classes, in particular physics, is really common which unfortunately drives so many people away from this exciting field.
I was born in Bremen, a town in Northern Germany, famous for their beer (Beck's), the Town Musicians (not sure how famous those are actually), and the muddy weather. In 2007, I moved to Leipzig in Eastern Germany to study physics. Leipzig is a beautiful city with a vibrant....
student culture. It's full of young people shaping the cultural scene (art&galleries, music, theater, dance,...) -- definitely worth a visit under normal conditions! Semiconductor physics found me in 2010, when I was looking for a topic for my bachelor's thesis.
That was the first time I came into contact with defects, and I kind of stuck to it, in one way or another. The great thing about this field is that you can choose between so many different topics and applications and always do something new, while at the same time you're using..
your skillset you already have. I worked a bit with fundamental defect research, then went into pure application research for my master's, where I studied Cu(In,Ga)Se2 solar cells in a company that made&sold these devices. After that, I felt I wanted to come back to university.
Started a Ph.D. @UniLeipzig, where I worked on transparent electronics. Super fun topic, so many different aspects that needed to be looked into! I finished my degree in 2018. After that, I had a short phase in Leipzig to tie up some loose ends, but I felt I needed...
to find something new -- in the end, I had been there for almost 12 years! In 2019, I started my current position @UniOslo as a postdoctoral research fellow. The group I'm working with ("Light and Electricity from Novel Semiconductors", LENS) is one of five groups organized...
within the Centre for Materials Science and Nanotechnology (SMN), which next to physical sciences also includes groups from the chemistry department. LENS does "application-motivated basic research" of semiconductors. Solar cells play an important role here.
Working here is a ton of fun! The interdisciplinary character of our center makes it easy to talk to people outside of your field, find collaborators and learn about what others are doing. At the same time, our research infrastructure, mostly located in a huge cleanroom, ....
makes it possible to do most of the processing and characterization tasks here quite efficiently and conveniently.
@MySci_PK What is Materials Science if not "all of the above" :P
I will now give a colleague training on an instrument that I'm maintaining in our electrical characterization lab. I'll be back afterwards, and then we'll talk science :)
@nikkiflausch Really?? I've played this game a lot but can't remember that little easter egg! That's so cool! 😁
@nikkiflausch I remember that mission, yes! Now I want to play that game again :D
@nikkiflausch I played it on the 3DS, they have polished the graphics quite a bit compared to the N64!
@goldclusters 1/ Good question! Back then, when I did my master's in 2010, perovskites were not really a thing. The company I did my research with was located in Leipzig, so my opting for it was mainly a question of convenience.
@goldclusters 2/ I'm not really up to date with regard to the literature, but both these technologies have their own issues. With perovskites there is the stability problem and the fact that lead-based systems work best (toxicity). For CIGSe, there is the Cd issue, and the use of rare indium.
@goldclusters 3/ Looking at the efficiency table Green et al. regularly publish, you can see how perovskites made about the same progress in less than a decade as CIGSe did, where it took more than 20yrs to go above 20% efficiency. This tells something about the potential of perovskite PV.
@goldclusters 4/ It may actually be easier to find solutions for the stability problem in perovskites, than find well-performing Cd-free buffer layers for CIGSe (but again, not really up to date on the literature here).
@goldclusters Sure thing :)
1/ So what IS a semiconductor? There exists a loose definition saying that semiconductors are materials with an electrical conductivity somewhere between that of metals (very conductive) and insulators (not conductive at all). Of course that is very difficult to quantify.
2/ What threshold value of the conductivity does the material have to exceed to qualify? This is not a good definition. We'll come back to one later. In terms of conductivity, solid state physics only knows two types of solids: conductors (metals) and non-conductors (insulators)
3/ The distinction is made by looking at where electrons in the solid "live". More specifically, which energies can electrons in the solid have? Atoms have fixed energies for each electron orbital. In solid matter, which is built up from atoms, this scheme is partially preserved. https://t.co/LKB9W6teJc
4/ Singe-energy levels from atoms will combine to broad regions with "allowed energies", called bands. Sometimes, these bands are being pushed into each other, and they merge into one broader band. In other cases, there will be a gap between some states -- the so called band gap.
5/ When we now "fill" these states (figuratively) with electrons, they will occupy the available states. When all electrons a material ahs have been "poured" into the solid, we get to an energy that separates occupied from unoccupied states. https://t.co/YTdMip8iOu
6/ In the example above, one band has been completely filled, and one is completely empty. There is no possibility for carrier movement in any of the two bands -- one has no room to move, the other one has no electrons. This material is an insulator.
7/ Let's assume our original simplified atom has one electron more. Building up a solid with it, this situation will result. Now we have free electrons in the band. This is probably a good conductor, i.e. a metal. https://t.co/2CbfzQhPO4
8/ This picture has no room for something "in-between". A material is either a metal or an insulator, and that seems to be the end of it. We will have to find a better definition. I can at this point already tell you that a semiconductor can only be obtained in cases with a gap.
1/ To approach a better definition of a semiconductor, we'll have to look at defects. What are they? Most solids form crystals. Crystals are pieces of matter in which atoms are arranged in a fixed pattern, the so-called lattice. Each kind of atom (or rather: ion) has its place.
2/ (I'll not talk about amorphous substances here; in these, "defects" are much more difficult to define.) If something in the crystal is not where it should be, this is called a defect. Atoms can be missing, replaced by another atom, or sit on sites not part of the lattice. https://t.co/xvJk47BFdc
3/ The first one is called a vacancy, the second an impurity, and the third an interstitial. These three are the simplest 0-dimensional (or point) defects there are, and probably also the most important ones.
4/ Because a defect disturbs the perfect lattice, it will introduce new electron energies into the energy scheme we have drawn that weren't there before. In some cases, these energies will end up in the band gap. Those are the most interesting ones! https://t.co/8lbEyhGuHc
5/ The one to the left there is really close to the lowest empty band (also called "conduction band"). If it comes with an additional electron, for example because the defect is an impurity atom with 1 electron more than the host material, this electron can easily leave...
6/ the defect and freely move in the conduction band -- we have made the material slightly more conductive. Adding impurities in a controlled way to manipulate the electrical conductivity is called doping.
7/ By choosing the amount of dopants, the conductivity can be changed by orders of magnitude, which translates into the property of semiconductors to have such a variable conductivity. This principle only works when there is a band gap.
8/ It also only works when defects with small energy separation from a nearby band (so-called "shallow defects") exist or can be found. This can be tricky, which I'll come back to later. So, how about this definition: semiconductors are insulators that can be doped.
1/ This definition is still "fuzzy", because it depends on the knowledge of appropriate dopants, which may change as science progresses. For example, until a while ago, a material like gallium oxide was considered an insulator. Today, we know.... https://t.co/PU5JeydTdH
2/ that by adding silicon to it, we can obtain semiconducting gallium oxide. Silicon was long considered to be a metal because the samples people studied contained so much "dirt" that they always were conductive. Today we know silicon as THE prototypical semiconductor, because
3/ we have figured out how to make clean samples. This brings me to the next point: abundance of defects. Theoretically, we can prepare any sample in such a way that it doesn't contain any impurities. Defects like vacancies or interstitials, on the other hand, also occur...
4/ in the clean lattice. In fact, the laws of thermodynamics demand that any sample HAS TO contain a certain concentration of these so called intrinsic defects (= defects that come from only displacing atoms of the host crystal).
5/ This means that we have to live with them being there! And that can make our lives as researchers quite difficult. The energy levels of intrinsic defects are often buried deep inside the semiconductor's band gap. For example, a free electron can get caught in it. That means...
6/ that it cannot contribute to conductivity anymore. For many devices, such as solar cells or LEDs, "deep" defects like that are detrimental to the performance. Control and engineering of defect formation is key!
We will see in the further course of this week that defects are not always unwanted. Gemstones actually get their beautiful color because of impurities! This picture contains a large variety of sapphire crystals. Adding small traces of titanium, chromium, or iron to... https://t.co/fKQsYawTUc
clean aluminum oxide Al2O3 (or corundum) produces electronic states in the band gap. Electrons in these states absorb and emit light of a particular wavelength. (image source: https://t.co/2zlRfrFSVa, author Wisebwoy, license CC BY-SA 4.0, https://t.co/JzqGWpdz3Q)
I think that is enough facts for today! If you have any questions, shoot :) I'll now have a cup of coffee, and then prepare a presentation I'll be giving on Friday.
@Mick__geek One of the best cities in Germany to live and study in, I think!
Time to call it a day! Tomorrow will be all about methods for detecting and studying defects, and I'll show you the instruments we use for that. I hope you had a good start into the new week!
1/ Good morning! Before we dive into how we can detect defects, I want to say a bit more about the importance of defect research -- not sure if that came across enough yesterday! More or less all of our modern-day electronics needs semiconductors to function.
2/ Microprocessors consist of incredibly large numbers of nano-sized electrical switches called transistors. The same type of devices is behind the electronics controlling the screens on our mobile devices. Solar cells are nothing else but a "block" of semiconductor absorbing...
3/ light and converting its energy to usable electrical power. LEDs are in a way a "reversed solar cell", converting charge carriers into photons. High-power electronics are part of our power grid systems, converting the electricity coming from power plants to "usable" values.
4/ For all these devices, it is extremely important that charge carriers can move as freely as possible. Defects can mess with that by capturing charge carriers. In some cases, already one defect per 10 billion atoms (!) can make the difference between a good and a bad device.
5/ This means that we need VERY sensitive equipment to find out if defects are present in this concentration range, and to study how they interact with charge carriers.
1/ There are many ways to detect defects in semiconductors. One of the "simplest" ones is related to the picture of the colorful crystals I showed yesterday. Electrons caught in defects can absorb and emit light. If we use a laser... https://t.co/DfJSSb8NQY
2/ to illuminate a sample, the electrons go into a short period of being "excited" (i.e. having a bit larger energy than in their ground state) and then fall back to where they were before, re-emitting light of a specific wavelength that we can detect.
3/ Each defect has characteristic emission lines, similar to what atoms do when you "excite" them. By identifying these lines, we can learn which defects are present in the sample. This method is called photoluminescence (PL for short).
4/ This is what a PL spectrum looks like. The material we are looking at here is silicon carbide (SiC), an important material for high-power electronics and quantum technologies. Here, we are only seeing a narrow wavelength window where the lines of the silicon vacancy "live". https://t.co/kH7B3aDX4x
5/ You can see two datasets here: one from a sample with only a few vacancies, and one with a lot. The signal intensity is related to the concentration of the defect -- more signal = higher concentrations. PL is not a quantitative method, it only gives relative information.
6/ Here are some impressions from our PL lab! The grey box with the yellow stickers is one of the lasers we use. The light is sent through a sometimes really complicated arrangement of optical components to the sample, which sits in a cryostat -- the blue cylinder to the left. https://t.co/JgTfL7foed
7/ Cryostats are chambers that keep the sample at very low temperatures (down to 4K). That can be important because thermal energy also interacts with the charge carriers inside the defects uncontrollably, which worsens signal quality.
8/ The silicon vacancy in SiC (more specifically the modification 4H-SiC) has become interesting defect for quantum technologies! The light that it emits is different from what we know from everyday light sources -- it only comes in packages of exactly 1 photon per defect...
9/ making the defect a so-called "single-photon source". Really valuable for secure quantum communication. Also, electrons captured in the defect show very long spin coherence times (I'll talk about that on Thursday!), so it can serve as a qubit in quantum computers.
@BarnabyWalters It's a class 3B He-Cd laser, so powerful enough to damage eyes if you look directly into the beam. We wear laser goggles when operating it, and of course the alignment is done very carefully to avoid light bouncing around. The optical table is also waist-high to reduce risk.
@BarnabyWalters Beefiness does also not necessarily translate to higher power. He-Cd lasers are more voluminous than diode lasers, but do not necessarily have higher optical power (but not a laser expert here tbh!)
We don't have to use laser light to excite the defects. The same can also be done using high-energy electrons. Electrons are charged particles, so they can be accelerated to high speeds with electrical fields & then shaped into a beam with magnetic fields https://t.co/nIkvyIe8B5
The electron beam is directed at the sample, where they excite all sorts of things, one of them being other electrons trapped at defects. This technique is called cathodoluminescence (CL) and can be done using a scanning electron microscope. This is our microscope. https://t.co/lZMdDGkGJI
The advantage of CL over PL is that the excited region is much smaller (PL: ~10 micrometers, CL ~100nanometers), giving it much better spatial resolution, while the spectral resolution is typically not as good. Upside is that you get some really nice micrographs of your sample!
1/ PL and CL are powerful methods, and we use them a lot, but the methods I specialize in use the ELECTRICAL response of defects instead of the optical one. For that, the sample structure becomes a little more complicated, which can be quite challenging. https://t.co/dLRFBs49qA
2/ The property used in these methods is the charge state of defects. Defects with electrons in them are more negatively charged than ones without electrons, and the process by which defects change their charge state (capture or emission of charge carriers) gives away details...
3/ of the defect, like where their energy levels are in the band gap of the semiconductor. Knowing that value is a central part of learning the identity of a defect. The problem is that normally all defects of a certain type have the same charge state in the entire sample.
4/ To make them change charge states, we have to apply a trick. We have to remove a part of the free charge carriers (those that move in a band). This new charge balance forces some of the defects to change their state. This carrier removal is done by bringing our sample...
5/ into contact with another material that has less or more electrons than the sample itself. Imagine you connect two glasses filled with water to different heights by a tube. Water will flow from one glass to the other, until the water level is the same in both glasses.
6/ This is the same principle: find a material with a different "sea level" of electrons than you sample, and bring them in contact. That creates a region close to the interface with almost no free charge carriers where the defects become "visible".
7/ This region is called space charge region, and the methods that make use of it are called space charge spectroscopies. These are what I mainly use in my research!
Our lab for these electrical measurements does not look fancy, but it is! It has five of these high-sensitivity setups, with cooling and heating capabilities and hardware that makes it possible to find tiny defect concentrations down to 1 in 1 trillion! https://t.co/0z0riuQSUY https://t.co/kJLegRaPqT
You see the small circles on the sample? Those are the contacts I talked about. Below them, inside the actual sample (the square), is now a thin layer without free electrons. That makes the defects in it detectable.
1/ Finding a suitable material for space charge spectroscopy on a new material can be super challenging. There are a few rules of thumb that one can use to at least identify candidates, but sometimes life is more complicated. Searching for contact materials is a science in itself
2/ This brings me to the material I'm mostly studying: nickel oxide. Super versatile stuff, has applications in all sorts of devices: solar cells, LEDs, smart windows, batteries, and detectors for UV light. As I explained yesterday, doping of a semiconductor is key to making...
3/ full use of its potential. People realized quite early on that nickel oxide (NiO) can either be doped by putting some lithium in, or by making samples that have more oxygen than nickel. In the latter case, nickel vacancies will be quite abundant, and they are a decent dopant.
4/ Although it has been very clear that these two methods work, people so far had no idea where the energy levels of these defects actually were in the band gap. That can be very important information when designing and making devices. This is where our most recent work comes in
5/ More or less by coincidence, we found a material -- fluorine-doped tin dioxide, FTO -- that does the trick. That allowed us to detect the two most important energy levels belonging to the two dopants in NiO, and closed, as they say, a "knowledge gap"! https://t.co/tA9NwciEEF
6/ This will also be the topic of tomorrow's live experiment. We'll be making NiO devices for defect detection, see if they work, and try to find new levels! It's a bit different from what I've done so far, so it might not work. But that's science 🙃
1/ Let's continue the tour through our labs a little bit! Most of our equipment for sample preparation is inside a 400m² cleanroom. You have to get into these fashionable bunny suits before you go in, to make sure everything inside the room stays as clean as possible. https://t.co/jDZhtVir4S
2/ A few impressions from the inside. We have wet benches for cleaning & etching, tools for metal deposition, furnaces for thermal processing and much more. https://t.co/Y7joE1KXCD
3/ The most important (and high-tech) tool for many of us is the ion implanter. It can take any elemental substance you want to shoot at your sample, ionizes it, and accelerates it to bombard you sample with it. Depending on the energy of the ions, they either end up... https://t.co/19WjJiDxPg
4/ inside the sample ("ion implantation") or simply fly through it while making a bunch of damage ("ion irradiation"). You can imagine that this is very useful for studying defects, because that is what it basically does -- creating a defined amount of defects. https://t.co/uA8UdACebI
5/ Now the coolest thing about this implanter is that it has a setup, very much like the ones I showed earlier, for electrical characterization hooked up to one of the beamlines. With this, we can irradiate or implant a sample and do defect studies without having to take... https://t.co/0JsbUBOo7I
6/ the sample out! This is really useful for implantation series, or when you want to do everything at low temperatures to "freeze in" what is happening in the sample after the damage has been done. As far as we know, this kind of setup is the only one in the world!
7/ It also has the added bonus of having this optical setup attached to it. With it, we can use light from a broadband light source to change the charge state of defects. That makes the entire band gap of the studied material accessible. https://t.co/va8jz0S1vs
8/ The online setup and the implanter were part of my original plan for tomorrow's experiment. It had to be postponed because the implanter is not operative at the moment. If you still want to see it, give my account (@rkarsthof) a follow! I'll post it there when it's possible!
OK folks, I'll be off for a moment, having the first meeting for a project I'm about to start working on. Really exciting! If there is anything in today's tweets that you'd like to hear about more, just let me know :)
@Dan_the_Manimal 1/ The optical experiments are usually done afterwards because they take a long time (~16hrs). But there are some things that we can in principle do in situ! I only really started using this setup a few months ago, and so far haven't done any measurements with it that...
@Dan_the_Manimal 2/ it was designed for. So this will be a first!
@MySci_PK You miss them? 😅 I always feel like I'm wrapped in plastic
Worked late today. Sometimes I really enjoy the solitude of empty labs and offices late in the evenings—at the moment it feels different, not quite right. Normally, I would probably rather have gone to the climbing gym on such an evening. Bouldering takes my mind off things.
This was November 3rd, just a few days before Oslo shut down. More than five months now! 😭 Of course, I know I'm also lucky that some things, like coming to the lab, are still possible. But I still really miss this. https://t.co/ugNQUrkL0H
@Learn_Electron @RKarsthof Not due to the pandemic, no! Luckily it's not to do with the UHV, just the electronics. A replacement part had to be ordered. Will only be a couple of days :)
1/ Today is experiment day! I told you yesterday that doing the electrical characterization of defects we would like to do requires a device that removes a part of the free carriers in the semiconductor. We will make such devices today. Our studied semiconductor is nickel oxide.
2/ We will make thin (~200nm) NiO layers on top of materials that induce this depletion of free carriers. I have already told you that we have identified FTO (fluorine-doped tin dioxide) as appropriate for that, but in theory, aluminium should also do the trick.
3/ Now, when I tried to make Al contacts on NiO before, it never worked. I don't really know why, but one big difference to the FTO samples was that in these, the NiO layer is deposited on top of the contacting material. Sometimes, the order of making layers makes a difference.
4/ So for today's experiments, we'll be depositing NiO ON TOP of aluminium, to see if that's true here too. For comparison, I will also make devices on FTO like before. To have even more to compare, I'll be using two methods for NiO deposition: evaporation and sputtering.
5/ In the first case, we heat up a bit of Ni metal in a vacuum chamber, using an electron beam until it starts boiling. We will also fill the chamber with a little bit of oxygen, which will give the evaporating metal a chance to oxidize, i.e. form NiO. This will then condense...
6/ on our substrates which are placed in the chamber. Sputtering is also a vacuum technique. A piece of the material we want to deposit (called target, see picture) is exposed to ionized gas that slowly ablates material from the target's surface. These parties then end up on... https://t.co/nOvEPgHnvq
7/ our substrates. This is what the sputtering system looks like in operation. The purple color comes from the gas we use (pure argon here). Sputtering is a bit more flexible than evaporation. We can also add oxygen to the gas, which makes the film more oxygen-rich. For NiO... https://t.co/OTRxrYfT3i
8/ that means we have control over the amount of nickel vacancies (remember, a really important defect in NiO!). This is not the case for evaporation, here we just have to live with the stoichiometry we get.
1/ The fabrication of these samples takes a lot of steps and can't be done in just one day, so I had to prepare a little. First of all, I cut the substrates (2 FTO ones, and 2 glass pieces that I coated with aluminium) into pieces. The picture shows the 2 Al ones (the foil is.. https://t.co/RKNZij0mam
2/ just for wrapping them). Unfortunately I forgot to take a photo of the FTO-coated pieces. They are completely transparent (as glass and FTO is), and are roughly the same size (some mm x some mm).
3/ The easiest step to proceed is now simply to deposit the NiO layer on top of these, such that it covers the entire area of the sample. That is, however, usually a bad idea. These heterostructures are sensitive to small non-idealities, and only one "bad spot" (that can be a...
4/ piece of conductive "dirt", like a larger metal particle for example) then ruins the entire sample. So what we want is to pattern the NiO layer into smaller structures, which then decouples them from one another. That increases the chance of finding a device that works.
5/ In side view, this is what we want. The thickness of the layers is not to scale here, the layers will be much thinner (few 100nm) compared to their diameter (few 100µm). The easiest way to achieve this is to put a "shadow mask" (=sheet of metal with holes in it) on top... https://t.co/VXbBtfpDRX
6/ of the sample while we deposit the NiO. The shaded regions then don't get any NiO deposited on them. There are several problems with this, one of them being that shadow masks can get really dirty over time, and it's near to impossible to align them when you want to make...
7/ more than one layer in different machines (which we will be needing). So no shadow masks! The alternative is something called photolithography, a technique that is also widely used for nano-fabrication in industrial processes. It uses a material called photoresist...
8/ a polymer that changes it's properties when exposed to UV light. You coat your sample with it, and then illuminate the regions that you want to be exposed. Then we put that into a chemical called developer which dissolves the illuminated parts again. This was, you get...
9/ something similar to a shadow mask, but it's fixed on your sample so you can move it around. Now you deposit your material on top of this structure, and afterwards remove the remaining photoresist again (this is called lift-off). Here is the work flow. https://t.co/Mf53antg6t
10/ This way, we get our NiO only in defined areas, while others remain uncoated. We're almost there, there is just one tiny problem: photoresists typically don't withstand temperatures higher than 150°C. I want to deposit the NiO at 300°C, so that won't work. We have to...
11/ make use of a trick: We'll replace the PR by a more resilient material that can also be easily dissolved later. We will call this a "sacrificial layer". It works this way: instead of depositing NiO directly, we first deposit zinc oxide (ZnO), a thermally stable but...
12/ chemically unstable material. It can be dissolved in very weak acids (here: phosphoric acid) which, at the same time, won't hurt the rest of our sample. We will need to use the negative of the original illumination pattern for the photoresist, but that is not a problem. https://t.co/XssaGlW4pk
13/ Now we have the recipe for making patterned NiO on our substrates! In the end, we will also make another thin layer of metal on top of the NiO -- this will serve as front electrode since NiO is not really conductive.
Here you see one of the Al samples after making small structures of photoresist (the brown stuff)—circular cross sections, a few hundred micrometer in diameter, 5-8 per sample. https://t.co/ajmXrapeMd
After ZnO deposition, I threw these in acetone, which removes the photoresist under the ZnO. You see how it crumples inside the circles if you zoom in a little. https://t.co/E0UeG2TE1I
This is what the sample looks like afterwards under the microscope. It's not perfect, there seem to be residuals of ZnO sticking over the edges a little. Photolithography always takes some optimization steps of your recipe before you get good results, but for the first attempt... https://t.co/k4dfBSZOqV
its not bad! I will now use these to deposit NiO through this sacrificial mask of ZnO, then the top metal contact. And then well throw them in acid to chase the ZnO away!!
[admin] "Defects Make Better Devices" Extended conversation with the amazing @RKarsthof is out now 👇🎙️ https://t.co/V6eqqYXbO7
One thing I really like about our photolithography is that it has a so-called maskless aligner. In many systems, you need a version of the mask you want to pattern into your sample. There are suppliers that make them for you, you only have to design them and send them the layout.
The downside is that this is not very flexible. If you want to make small changes to the layout, you have to order a new mask, which can take a few weeks to get delivered. Maskless aligners use a write head with an LED in it to directly write your pattern into the photoresist.
You design you layout on the computer, upload it to the aligner, load your sample and then it writes the pattern like in the video. The whole process takes only 20mins! The resolution is very good, you can get features down to a few micrometer in size with this. https://t.co/7f4ms5mLIU
@inaquantumdot The one that we use here is simply called LayoutEditor. There is a free version that comes with some limits on how complex your designs can be, but it's enough for most things we do here!
The two depositions – evaporation and sputtering – are running now. I'm expecting that to finish in two hours, and then we still need to make the front contacts. Looks like I will do the characterization tomorrow! The evaporation is difficult to take photographs of. The bright.. https://t.co/IxxfYFYbBJ
spot is the glowing nickel metal being heated by the electron beam. The sputtering always looks pretty though 😊
The samples from sputtering—if they work— will be interesting because of an issue that we found a few weeks back. The NiO layers our system makes are contaminated with quite a bit of iron, which comes from (unwanted) ablation of components holding the... https://t.co/U5rnDHeScC
target in place. Here you see a comparison between a clean sample from evaporation (right) and an Fe-contaminated one from sputtering (left). The color is a hint that the iron produces a deep-level defect that absorbs visible light. https://t.co/egRmmQC2UD
It would be really cool to find that level by space charge spectroscopy measurements, which is why this sample set is exciting!
Both the sputtered (1st) and the evaporated (2nd) films are now done, and ready for the next step: the top contact. I'll use nickel for that, also by electron beam evaporation in the same machine we used for the NiO. https://t.co/8OchP4PKvV
Unfortunately, the sputtered sample on Al back contact broke into 3 pieces when I tried to get it off the double sided tape that held it in place 😭 that cost us a few devices, but there is still 4 complete circles on there in total, so I just mounted them all (this time no tape) https://t.co/sed0TdU66d
I'll do the deposition, and then leave for today! Samples breaking = usually a sign to call it a day. Also, the next step involves handling acid, and it's better NOT to do that after 6p.m. when no one is here! 😅
Good morning! Our four samples (one of them in 3 pieces) are now covered with 50nm of nickel, serving as a front electrode. Now, to obtain patterned NiO/Ni structures on the back contacts, I will dissolve the ZnO sacrificial layer in dilute phosphoric acid! Fun! https://t.co/I43K5YBTbm
Look at that acid, eating the ZnO! 😍 The back contacts are now almost completely exposed again.... https://t.co/gWyQu8ZR3M
Aaaaaand it worked! This is how our four samples look after the completed fabrication process. With all steps included, the whole thing took me ~1week from cutting the substrates to complete devices. https://t.co/5ibc8qZvyR
https://t.co/7LLjdnko66
There are still a few things that can be improved. The contacts are quite large, so there are not that many of them, which makes for bad statistics. Also, their edges aren't very smooth, but that can be sorted out by tweaking the lithography step some more.
To test if these devices work, I'll do a pre-characterization called current-voltage measurements. If the thin region without any free charge carriers exists, as intended, it will give away its presence because it has a very low electric conductivity. https://t.co/JM7LSFFNLI
Currents can only flow when there are charges to carry them, and a space charge layer has practically no charge carriers. Applying a voltage of one polarity will only remove more carriers, and the conductivity should go down even further, while applying a voltage of opposite...
polarity will fill the semiconductor with free carriers. For that polarity, the device becomes conductive, and there should be quite a large current flowing. A device with such an asymmetric current flow is called a diode, and observing it on the sample is a prerequisite for...
doing the defect measurements I want to do.
I have now tested both samples on aluminium back contacts. Unfortunately, the current flow is completely symmetrical, and also quite large. So these can't be used. :(
For the evaporated NiO on FTO, things are also not ideal. There is definitely some asymmetry, but the currents are still much too large (I'm hoping for something like 1microamp for negative voltages). But this is not unexpected, because the evaporated NiO does not have any doping https://t.co/lXP7ECKx42
So, bad news. The last sample, the sputtered one on FTO, was the one I originally had my biggest hopes in. Turns out it also does not show diode behavior. So none of these can be used for defect studies :( That is science, folks! As I said a couple of days back, making these...
devices can be a real struggle. Sometimes what you've successfully done before doesn't work the n-th time, and you have to figure out what went wrong. Still a bit disheartening!
So that was quite a bummer! I'll have to go all the way back and identify what the reasons might be, then repeat the fabrication. Usually, when that happens, I don't really feel up to doing it right away. Those of you who do research: how do you deal with failed experiments? https://t.co/8id8TMUNKq
Today I had planned to talk about a little about the things defects can actually be good for. So far, I only mentioned the downsides of having them in semiconductors, but there is actually many ways of turning their presence into something useful: the functionalization of defects
The live experiment took longer than I had expected, so I'll make a shorter thread now about one of the ideas people have for defect functionalization, and maybe another one tomorrow, if you're interested!
1/ How defects can be useful for neuromorphic computing: a 🧵! A defect of any species is tied to a certain site in the crystal lattice. For example, a Ni vacancy in nickel oxide can, by definition, only "live" where Ni atoms belong. But this doesn't mean defects don't move!
2/ Quite the contrary. High temperatures, electric fields or other driving forces can lead to atoms redistributing in the lattice. By moving a Ni atom into the Ni vacancy, the defect and the atom "swap sites", which can happen again with the next Ni neighbor and so on.
3/ This diffusive movement of Ni vacancies at higher temperatures is something we have directly observed recently, by doing electrical measurements with an extremely high-precision method, called broadband dielectric spectroscopy (BDS). Here's the paper: https://t.co/sAiP9jQq9H
4/ Because the Ni vacancy is also responsible for the electrical conductivity in these samples, that means that by targetedly moving Ni atoms (or vacancies) around, we can in principle create and destroy conductive paths through a NiO layer.
5/ This is related to a phenomenon that occurs in a lot of metal oxides: resistive switching. Simply by applying a voltage across a piece of them, they change between a conductive and a resistive state. The transition between these can be incredibly fast -- below 1 nanosecond!
6/ There are two general mechanisms that cause this switching: the filament and the interface mechanism. Here is a schematics of what happens in these two. In the filament process, defects migrate to form a conductive chain that connects the two electrodes. In the interface... https://t.co/VmWtOsdqWJ
7/ process, the cell's resistance is increased because defects accumulate below one of the electrodes. Both of these processes are reversible, i.e. they can be repeated many times. This is similar to what conventional transistors in modern microelectronics do, just A LOT faster
8/ They are also much simpler from a device design perspective: they only have two electrodes. Transistors typically have three, separating current conduction and control over conductivity. The simpler principle of resistive switching cells and their high speed makes them...
9/ good candidates for artificial neurons! Here is a relatively recent paper with a tutorial on how one could use resistive switching cells to emulate biological brains: https://t.co/BSTP6gvNre
10/ So far, nothing of that magnitude has been achieved yet. There are many problems around these resistive switching cells, many of which relate to the fact that we don't really understand the physics behind the switching. Since it is ultimately because of defect movement...
11/ this means we need to understand better how (and which!) defects move in these materials, how they form larger structures in electric fields and temperature gradients, how they break down again, and what can be done to make the process more robust and predictable.
12/ I think I'll leave it at that for now! Let me know if you have questions :) By the way, this topic is also the focus of a grant proposal I recently submitted. Finger-crossing is highly appreciated!!
@goldclusters 1/ That is a difficult question! If the defects you have in your quantum dots are shallow (=dopant), i.e. they produce free carriers, that can mean the particles form diodes with other materials. If they are deep levels, less so! Doping beyond a certain levels can also kill...
@goldclusters 2/ the diode behavior, because the space charge layer becomes super thin, so the electrons can tunnel through.
Hey everyone! I'm a bit swamped, but I intend to make another thread today. It would either be about quantum technologies and the role of defects in them, or about transparent solar cells, my PhD topic from back in the days! I'll let you pick :)
Also I promised to do a Q&A session for today. So if you have questions, post them in the replies👇👇👇, and I'll do my best to answer them! ☺️
I think for talking about quantum tech I'll have to prepare a little more than I currently have time for, so I'll just start with transparent photovoltaics, and see what I can do for the other one on the weekend! Hope that's ok
1/ What is transparent photovoltaics? The sunlight that reaches Earth's surface contains up to ~1 kilowatts per square meter of optical power. That's quite a lot: every m² receives enough power to supply a vacuum cleaner! This immense potential is the reason why photovoltaics...
2/ have become so important in the past two decades. To harvest all that energy, we use solar cells that we put up in areas that we don't use otherwise, like on our roofs or as huge solar power plants in the uninhabited countryside. But there are many surfaces around us that..
3/ are also illuminated by the sun, but that cannot actually be equipped with conventional solar cells. Large glazed facades of buildings, or their roofs. Or cars, or even the displays of our mobile devices. You don't want to have normal cells on them, because they change...
4/ the way these surfaces look, or even function (a window would become completely opaque). And here is where transparent photovoltaics comes in! Half of the power contained in the sunlight is in wavelength regions we cannot see. Most of that (93%) is in the infrared (IR)...
5/ and about 7% in the ultraviolet (UV) spectral ranges. Solar cells that use this light, but let the visible parts pass through, would be almost invisible to the human eye, while providing us with electrical energy. And because they're invisible, we could put them wherever!
6/ There is an incredibly large amount of research around this. See this review: https://t.co/6U8u1m4a2Y
7/ The tricky part is to get the visible light (medium photon energy) through while at the same time absorbing the lower-energy photons from the IR. From the perspective of a semiconductor physicist, making a UV solar cell, however, is the obvious first step. All we need is...
8/ a semiconductor that starts absorbing light in the UV. It is then naturally transparent for all the lower-energy light. It won't convert IR light though, so it is going to be less efficient. But this may be compensated by the simplicity of the device, of its fabrication, and..
9/ the low cost of the materials we use. In my PhD thesis, I studied (among other devices) transparent solar cells made from the inexpensive and easy-to-process materials zinc oxide and nickel oxide.
1/ The transparent solar cell project became quite a success very soon after we started. We found that a simple device, that basically only consisted of a layer of ZnO in contact with a layer of NiO, plus a front and back electrode, did the trick. The cells we made immediately...
2/ beat the previous world record of the conversion efficiency for UV solar cells by a factor of 20! It was still quite low though: only 3.1% of the power in the UV spectral range were converted into electricity. Here is the publication we wrote: https://t.co/Y5NGp3daK5
2*/ The paper was also selected for the journal cover that month! I learned a lot of things about graphics design (mostly how not to do it...), and in the end, this came out: https://t.co/yK7t7UpkHv
3/ After that, I started looking more into what still went wrong. And it turned out defects were behind most of it! If you put two crystalline materials together, the interface between them is, in principle, nothing but one extended defect. And this defect can do all...
4/ the things 0-dimensional defects also do. In particular, they also capture electrons if they have the chance. The ironic thing was that some parts of the sunlight messed with the way the interface defects interact with the charge carriers in the two semiconductors...
5/ mainly in the ZnO, because that is the component that does the light absorption and provides charge carriers loaded with the energy of the sunlight. The NiO is "only" responsible for making them move in a particular direction, so we get a current.
6/ When the light was on, the defects at the interface suddenly started eating away much more charge carriers from both sides of the contact. So illumination made the cell perform much worse than one could expect from how it behaved in dark. https://t.co/NdhZrh1H2l
7/ Interfaces between two different materials are often a problem in photovoltaics. It takes some challenging engineering of the interface to make the cell perform well, and in the end, this often has to do with controlling where defects live.
8/ To make things more ironic, I then found a second loss mechanism that further decreased our efficiencies that ALSO had to do with light! Ni atoms from the NiO diffuse into the topmost regions of the ZnO where they replace some of the Zn atoms, producing...
9/ the nickel-on-zinc substitutional defect! That's a bad one because it sits deep inside the ZnO band gap, so that it can kill charge carriers coming by and trying to cross the interface to the NiO. Here's the paper: https://t.co/B9aLpL5zW6
10/ In spite of our defect-related troubles, the device was still at 3.1% efficiency. With the two above loss mechanisms suppressed, that could be 15%! And even with 3.1%, you can do a few things. Some applications don't really need a lot of currents -- they mostly want...
12/ voltages. And our cells were quite good at providing that! We developed this mini-module (1x1cm) with 49 cells connected in parallel and in series, that gave an output voltage of 3.5V, and maximum power of 12µW. Low-power electronics could live off of that! https://t.co/RyjjKtruKZ
13/ Overall, it was a really fun project. It had a somewhat crazy initial idea, fundamental science (-> defects), but also device development! Some tech companies came to us with ideas for collaborations, and it attracted a lot of students who wrote their theses about it.
14/ That's it for today, folks! Time for the weekend. Hope you found this interesting!
@takttiger Thank you! That's great to hear 😊
@takttiger It's true, defects are often treated as a "side problem" in typical semiconductor textbooks. Orton&Blood do it quite thoroughly though, if you're looking for general background and characterization techniques.
@takttiger If you're more interested in material-specific knowledge, there are entire books or at least book chapters dedicated to defects in particular semiconductors, but that's typically more on the experimental side.
@Learn_Electron I'm not quite sure what you mean by the first part? Yes, defects kill light emission, but that refers to a specific type of light emission. Excited electrons in the conduction band that recombine directly with free states (holes) in the valence band. Trap states can be a more...
@Learn_Electron Efficient (fast) way for the electron to do that. If that happens, the recombination type changes from radiative (with light) to non-radiative (no light). Light emission FROM defects is another thing. Here we use the electron permanently captured in the defect itself to excite..
@Learn_Electron and return to ground state, where it then can emit a photon. Direct and indirect transitions are terms only defined in band structures, i.e. a non-local picture. Defects are localized states, therefore do not have direct or indirect transitions (my view).
@Learn_Electron That does sound quite frustrating! I don't know your growth systems, but that can be a lot of "hidden factors" that you don't control (yet). But for that to work out, you really need to be an expert on what you're doing, and how.
@Learn_Electron I assume that by defect stoichiometry you mean defects that come from impurities? That's a question I cannot fully answer, because strain-induced trap states are something I've never really looked at. These would texhnicl fall under the "extended defects" category, and I mostly
@Learn_Electron Study point defects. But I would say that it probably depends. On a lot of things! Which semiconductor? What type of impurity? Indirect or direct band gap? Contribution to what, which property are you interested in? That can be a whole book chapter 😉
@Learn_Electron That would be cool, but I've used our schematics software 4 times now, and only for very easy things (max. 2 layers). Don't think I can fill an entire thread with my mistakes 😅
Good morning! This weekend's tweets will mostly be about Norway and Oslo! I'll start with a few impressions of Oslo, Norway's capital. It is not a huge city, close to 700k people live here. Pictures show the main station, Stortinget (the parliament) and the Tjuvholmen area. https://t.co/HJDBVnrJpG
Oslo is situated right by the sea, at the Oslofjord. Sometimes it's difficult thinking about it as sea though, the fjord is quite narrow and looks more like a river, and if you're far up the city, it's almost invisible! Also there are a lot of small islands in the fjord. https://t.co/UWfZsZiXBK
For someone coming from a big city, Oslo can seem a bit "sleepy" regarding options for going out. But the true beauties of Oslo lie outside the city borders! Woods and mountains for hiking and running, biking, skiing and all that are literally just a metro ride away! https://t.co/hast1YHUUV
These woods are also a rock climber's/ boulderer's paradise, as they are full of boulders with high-friction surfaces, protected from wind and weather by the trees. ❤️ Really looking forward to outdoor climbing season!
That proximity to nature sometimes also makes for an interesting work culture: often people show up to work in their running gear, or with their skis or a hiking backpack because they've got a trip planned for after work!
The stunning nature is mostly what makes Norway incredibly beautiful country to travel. Most of Norway is uninhabited and untouched nature is extremely valued here. At the same time, there exists a concept named "allemannsrett" which guarantees that everyone has the right to... https://t.co/p6uhdt7vEI
not only walk on every piece of land, owned or unowned, but also make use of it, like eat the fruit that grow there or even make camp, given that you stick to certain rules, such as not doing any damage to the nature, and keeping distance to buildings. https://t.co/mw1FNZaf1T
This system works incredibly well here. People make sure they leave the paths they have walked on or sites they have made camp at in the same state as it was in before. Something that I'm quite sure would not work so well on Germany, for example.
Here are some more impressions, from Hardangervidda national park. Some of these parks are so large that you can walk for days and never see more signs of civilization as single wooden cabins for shelter! https://t.co/c5oeJop1uw
I have been quiet today—the week was quite exhausting and stressful, I'm really looking forward to and in need of Easter holidays. So it was a bit hard for me to find the energy for tweeting today.
I think this is something many of us need regular reminders of: just because you really enjoy doing something doesn't mean you don't need breaks! Probably the opposite.
I still want to say I really had fun this week! Hope I could show you the fascination of defects a little bit :)
[admin] Thank you to @RKarsthof for a wonderful week of science about defects and showing us around your experiments and Oslo. ☺️ Listen to the podcasts 👇 to know more about Robert Short https://t.co/kEcoWsUUky Long https://t.co/V6eqqYXbO7
El-abed Haidar
[admin] "2D Materials - to Twist or Not to Twist" Please welcome @ElAbdleb and listen to the podcast ton know what is coming your way this week 🥳 https://t.co/vRXLZGg5xG
Hi everyone, my name is El-Abed Haidar from the school of physics from the faculty of science and I will be taking over the account with exciting density functional theory work. The energy will be a bit different! @sydney_physics @Sydney_Science @Sydney_Uni I have one question: https://t.co/X2I9pF958v
Here we go about my PhD motivation: Intense research is carried out by nano-electronic researchers around the world seeking promising alternatives to the current silicon based-nano technology. One way, is potentially replacing such electronic device with carbon nanostructures https://t.co/gWm5IGUprh
For example, graphene promises to achieve smaller and faster transistors due to the exceptionally high electron mobility, however, the lack of a band-gap is a severe problem. Recent research indicates, however, that through various approaches, a band-gap can be made...
Carbon-based nanomaterials(Fig.2) are interesting since their discoveries, and plays an increasingly significant role in nanoscience and nanotechnology with new discoveries aiming to enhance their fabrication and properties.(Alexander L Ivanovskii 2012 Russ. Chem. Rev. 81 571) https://t.co/y6nrvmRwjI
With that being said, my PhD objective is to theoretically investigate, through accurate quantum mechanical first-principles calculations, new promising carbon-based structures for applications in the nano-technology industry such as sensors, semiconductors and superconductors. https://t.co/4YRaZBvNat
The investigation requires a detailed understanding of the properties of matter at the nano and atomic done via Density Functional Theory (DFT). My co-supervisor @Sherif_A_Tawfik has given a great talk about the basics of DFT check it out! https://t.co/xBv5CvXbPH via @YouTube
DFT can be used in interdisciplinary purposes from physical, to chemical, to biological and materials science and engineering. Also helps with the prediction and identification of new promising device materials and structures. I know right! https://t.co/3dECQMy5F7
Unfortunately its becoming too late here in Sydney (almost 2 am), but I will do my best to tweet more on a daily basis as I snapped my ankle ligaments (lets leave it here). But on the plus side, i can write up my paper and tweet you guys about DFT #phdlife #phdforum #phdvoice https://t.co/NQgaL0WWUG
I told you I will be tweeting a bit different from the rest. So, for now (as I am a football and wrestling fan) coming from one of the best wrestlers today: https://t.co/dlzmBvh1zE
@FabMess1978 I know right. Love it when scientists come together https://t.co/fKmedbAgz5
Today's thread on one of the DFT studies i had so much fun working on: MOLETRONICS: The study of molecular devices by using a molecule to potentially build an electronic device usually done by connecting the molecule to gold due its high conductance and compatibility1/n https://t.co/liXuGF8gIH
My love for moletronics was inspired by @ACSChemRev paper back in 2016 DOI: 10.1021/acs.chemrev.5b00680 Chem. Rev. 2016, 116, 4318−4440
So why the big fuss? The story is about how electronic devices were the size of a room and ever year or so the device would get smaller and smaller and smaller to the point that we are capable of making a device using a DNA type of molecule and stick to gold, silver or such...
With silicon-based technology almost reaching the limit and us living in the Internet era which has almost infinite amount of information and data to be processed, we need alternatives not only cheaper but also capable of handling such larger amount of data..
But to make even smaller devices or what is known as miniaturization of electronic devices is always very challenging, which can be explained from either the issues with such technique or even simply not understanding enough how the electrons moving around such devices works...
So for example to be able to use almost 1nm molecules, within a device to perform like a switch or increasing the flow of current or as a memory allows us to say that molecular devices have the potential to maybe replace traditional solid-state device in the near future.
The picture below shows how a molecule is sandwiched using gold. As for now I will have to sleep as i have a couple of tutoring hrs to work on in the morning. Hope tomorrow i can continue the story further. AS always GOOD BYE AND GOOD NIGHT BANGGG!!!!!! https://t.co/8Q7NMtSbl3
[admin] "2D Materials - to Twist or Not to Twist" Extended conversation with the amazing @ElAbdleb is out now. In this podcast Al Abed speaks about his science career and his favourite research project. 😉 https://t.co/RqX0oHZ8F4
Today, I continue talking about moletronics but more close to my heart where @Sherif_A_Tawfik and I started worked on my first paper. The story is about a molecule called azulene quinone. Azulene is the molecule below made of 10 carbon and 8 hydrogen atoms which i will show next
Below is azulene where the IUPAC rules only allows us to show the carbon bonds. I said azulene quinone so where is the quinone or hydroquinone? Quinone (Hydroquinone) simply oxygen (hydroxide) bond on any of the carbon atoms below. Next question: Why did we choose such molecules? https://t.co/beOgkluwmM
Azulene (Az) are non-Alternant hydrocarbons (has odd hydrocarbon ring) and have shown enhancement of molecular electronic devices performance compared to Alternant ones with superior electronic properties based on experimentalists and theorists. Next more about AZ & their quinone
Azulene quinone used in electronic devices was reported first from 1,3-Az connection with conductance at least one order of magnitude lower than that of 2,6-Az and 4,7-Az. In other words, connecting Oxygen onto 1 and 3 had less change of passing current that the pair 2,6 and 4,7 https://t.co/vQa2XzDCfV
Many combinations can be done and was shown experimentally and theoretically (or even both) resulting in showing that maybe can be the next big thing. Problem is there are still a lot of cool combinations which have not be tried yet and that is what we want to try and do here.
This work studies switching behaviour of azulenequinones and their hydroquinones:1,5-azulenequinone-2,6-dithiolate(a), 1,7-azulenequinone-2,6-dithiolate(b) and their respective hydroquinones:1,5-azulenehydroquinone-2,6-dithiolate(c) and 1,7-azulenehydroquinone-2,6-dithiolate(d). https://t.co/TEH4bJEZas
Now the names are very long and reciting each and everyone of them in the paper would have been very painful. https://t.co/ndkFkNvX0K
So we need acronyms to make everyone's lives much easier: So for simplicity we use the following respective abbreviations (15Q and 17Q) and (15OH and 17OH) for azulenequinones and hydroquinones 2,6-dithiolates. ‘‘2,6’’ dithiolate indicates the positions of the sulfur atoms https://t.co/MAvIkv8m1N
There is one other new word i used switching which means yes a switch in a device as in ON and OFF where ON (OFF) means a lot (very small) of electrons ( leading to the concept of current) that goes through the device as shown below. https://t.co/wPuMoQ3z9l
I will try to continue the story but what we will study using DFT and DFT+NEGF is how does each molecule act when connected to gold is under a battery? I will explain what is DFT+ NEGF more next time and then from there we can explain the results. But for now https://t.co/p4Kij0GB9q
Sorry for being late as I was trying to finish up my work. So today I continue my last work on azulene quinone and how we found out it can act as a switch. Mainly we will be studying the 4 molecules I mentioned last time by sandwiching them into gold electrodes and apply voltage https://t.co/oA31IVmtTl
#PhD #Physics #phdchat #SIESTA So this is my first PhD paper where the molecules involved are wired between two gold electrodes. We then calculate the electronic transport properties using the DFT+NEGF formalism as implemented in TRANSIESTA using the SIESTA @SiestaDFT software.
Before we talk about the results in SIESTA and TranSIESTA, we need to give some insight on what is DFT AND DFT+NEGF respectively. Otherwise, going through the results without explaining a bit of physics behind of it makes you guys wonder what is going on? https://t.co/PD1D1uJEdY
Density functional theory (DFT) became the method of choice for the calculation of the electronic structure of atoms and molecules in both the teaching and the research environments. But it still retains several limitations due to the fact that it relies on approximations. https://t.co/YCSsQFGbc7
The main goal is to solve the time independent, non-relativistic Schrödinger equation for molecular systems. Part of it is well-known but there is also an unknown part where all the approximations take place. The more accurate it is, the more computational time it takes.... #DFT https://t.co/9Z8Ts9A2AH
We are studying a molecule connected to a battery, we have to be careful that the system is no longer in equilibrium because charges are going to move around. Thus, a theory to deal with non-equilibrium along side solving the Hamiltonian is needed. That's where DFT+NEGF jumps in
Inspired by Quantum Transport Modelling From First Principles invited paper @IEEEorg Proceedings of the IEEE | Vol. 101, No. 2, February 2013 DOI:10.1109/JPROC.2012.2197810, i will try my best to give a bit of math and physics behind DFT + Non-equilibrium Green Function (NEGF)
Below shows the transport model made of a scattering region+left/right leads extended to electron reservoirs at infinity where bias voltages are applied and electric current is collected. The scattering region includes layers of the leads’ atoms as indicated by the buffer regions https://t.co/M18u6ViEJ2
At equilibrium, the electrochemical potential of the two leads are equal. When a bias voltage V is applied between the leads differ by eV where e is the electron charge. NEGF technique is needed to find the density matrix of the system. This is where TranSIESTA does its magic https://t.co/kRjOBXjX05
The DFFT+NEGF theory will allow us to find the current is calculated from the transmission probability (T (E, V)) based on the Landauer-Buttiker formula shown below where the Green Functions are found in both equations. That gives a very briefly idea on DFT+NEGF https://t.co/4xNUQMoA8e
tomorrow I promise i will go through the results and try in a nice format ( better than today) to tell you the entire story #Physics #sciencetwitter #phdlife. Hope you guys are enjoying the tweets and I will do my best tomorrow. But for now as usual https://t.co/9YkaPTDTxK
Today i will continue my @PCCP journal paper results which includes DFT, DFT+NEGF transport calculations and graph theory (more on that later on). Hope to read your questions if you have any or just here to enjoy the ride. Without any further delays: https://t.co/3O4bjP97Om
We will show next the current–voltage (I–V) plots for the pairs of molecules (15Q, 15OH) and (17Q, 17OH). The current (I) is calculated as a function of voltage (V) from -1.2 to +1.2 V. As a reminder 15Q means oxygen is found on 1 and 5 of azulene below and 15OH means OH instead. https://t.co/9s5tQE8Hf2
For 15OH, a rapid increase in current when increasing bias, while 15Q has a notably lower current throughout the bias window like a switch. The (17Q, 17OH) results show a similar trend, but with a reduced current. Will show you the switching ratios to try and make things clearer. https://t.co/qYcPwBFZy9
The switching ratio (SR) defined as the higher current (ON) over the lower current(OFF). The figures below show for the (15Q, 15OH) and (17Q, 17OH) systems. The SR value for 15 reaches ~35, whereas 17~5. This indicates that molecular switching takes place at low bias voltage in https://t.co/uya6r4S6SG
both cases, but with different switching magnitudes,& for the reverse redox mechanism. Redox means replacing two oxygen atoms by OH bonds for 15Q and 17Q leads to inversion of switching: in the former it switches the junction ON, while in the latter it switches the junction OFF https://t.co/P8kFOBawqE
As a reminder also, current is described by the integration of the transmission probability (T(E)), which is a result of the detailed electronic properties of the transport system. Therefore, to further investigate the current and switching behavior, we calculate T(E)
T(E) is plotted as a function of both energy (with respect to the Fermi energy and bias voltage. The ‘‘X’’-shaped white lines indicate the linear relationship between bias voltage and energy (V=+or - 2(E-Ef)). For any voltage, it's the energies in the upper (or lower) triangles https://t.co/eX4SMAh29R
Not the left and right triangles which are outside the accessible region. Within the bias regions, T(E) in the two OFF states is negligible (dark blue), while in the ON states, it is modest (light blue), leading to the absence (or very low) and presence of current, respectively. https://t.co/Ogh64mYOPU
Tomorrow I aim to continue the story by aiming to give everyone who is following this thread an understanding of the physical reason for the features of the transmission function, by considering the electronic structure of the free molecular systems. Its 3am here so until then https://t.co/Cbi1p0EkxL
@BiffoAbdulkadir I assume WE is T(E). So, in that case, we are plotting the transmission probability vs voltage vs energy shifted with respect to the fermi energy. Does that make sense @BiffoAbdulkadir ?
@BiffoAbdulkadir Thank you very much! The fermi energy is usually for both electrode and scattering region found after a DFT run. Will continue the thread tomorrow as its 3 am. I would love to but no more energy :( https://t.co/WMzdjHPtfZ
Quick recap: The electronic transport properties of molecules when subtended between gold electrodes showed the reduction(oxidation) of 15Q(17HQ) led to a significant current enhancement compared to the respective oxidation(reduction)of 15HQ(17Q). Thus, ‘‘switching on’’. SO: https://t.co/1yexewjutP
To explore the underlying reason for conductivity change, we first plot the transmission function on a logarithmic scale versus electron energy (given with respect to the Fermi energy) for the four systems at zero bias voltage. Something only shown in zero transmission can do so:
That reason is destructive quantum interference (DQI). Quantum interference is a purely quantum mechanical concept explored in different transport device studies. Exploring it at molecular level provides new insights towards manipulating electronic transport at the wavefunction https://t.co/VkC4FZajlH
level through chemical design and electrical control. The DQI mechanism in molecular transport disrupts the conduction of electrons through the molecule resulting in current suppression. DQI prediction in molecular electronic structures has been suggested through several models. https://t.co/w5B1XoqoJk
However, although there are some contradicting conclusions, in particular, for the case of azulene, there is controversy as to whether DQI exists in certain azulene derivatives. To find DQI, look at T(E) at 0 V and find an anti-resonance dip around the Fermi level. Lets see! https://t.co/Nf0mX8r2OJ
Figure below shows T(E) plotted on a logarithmic scale at zero bias for the 4 molecules. We use logarithmic scale to highlight possible anti-resonance. We see no such dips in the region of the Fermi level. Thus DFT + NEGF does not identify the presence of DQI in these systems. https://t.co/ZEBKInZmB7
We were stuck and we needed something to at least give more insight to our story. That's when I read this beautiful review paper called Quantum Interference, Graphs, Walks, and Polynomials By Y. Tsuji, E. Estrada, R. Movassagh and R. Hoffmann, Chem. Rev., 2018, 118, 4887–4911. https://t.co/G0l5kNV5HP
Graph theory gave more insight: the ‘‘graph’’ characterizes the molecule as being made of vertices and edges which signify the atoms and their bonds respectively. This is much more straightforward than utilizing purely mathematical Green functions needed in DFT+NEGF. So: https://t.co/yY4d9dA2gg
This molecular graph is represented by the vertex adjacency matrix, A, which is an N by N matrix, with N being the number of atoms and holds the information on how the vertices inside the molecule are connected. The inverse of A as shown below will allow us to search for DQI. https://t.co/XcRFD53if7
That is, 0 in the elements of the Green’s function matrix, will signal the presence of DQI. To get A we consider all bonds like: between atom 1 and 2, so element in A is 1. If we look at 1 and 3, that element is 0. If we consider 5 and 13, different atoms would mean not 1 https://t.co/kNAweO0E0n
From A, we determine the inverse and consequently the Green Function. We are mostly interested in the path from atom 14 to atom12 (A14,12 or A12,14) (from one sulfur atom to other sulfur atom).The value of the matrix element for 15Q is not zero https://t.co/VbB6TINens
Hence predicting no DQI, in disagreement with the DQI graphical scheme14,15 but in agreement with the DFT–NEGF result. Therefore, the present results highlight, in particular, that there are still questions concerning the DQI graphical scheme agreement in an azulene derivative https://t.co/Izp7ZpHQpu
That is about it. I tweeted too much but hopefully the story made some sense! https://t.co/MN4GG6aZ7W
For the next episode i will move to 2D materials and twistronics. Hopefully I can give more explanation on what I am writing up as we speak! https://t.co/l1SkgIMx6v
Until then https://t.co/e2W1XvBlAl
Marjorie Ladd Parada
[admin] "Melting Ice with Very Expensive Lasers" Please welcome @M_LaddParada for a week of amazing science and listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/YcN1L2HXQJ
Good morning everyone! (at least in Sweden). I'm a postdoc working @Fysikum AT Stockholms University, working on amorphous ices and supercooled water. I'm super happy to curate this account for a week!
Later today, I'll be introducing myself a bit more, how I came to work in this area. But please bear with me today a bit as I'm writing a grant proposal!
For those of you who don't know, we scientist keep having to ask for money to do our researcher. So in a way we're like entrepreneurs always needing investors ;).
So today, I ended up taking a morning walk instead of my usual lunch or evening walk. My motivator: need to take the rubbish out #healthywalk
I have to say, it was definitely better than my early morning walk I take twice a week (avoiding public transport because of a certain pandemic) and even better than my lunch walk because there were so few people around! So nice and calm.
Admittedly, it's a blessing to live in Stockholm. I live in one of the islands, so after a few minutes I am next to the water! And yes, this is how Stockholm looks in spring. #spring #water #lovestockholm https://t.co/AdRiEHIJgf
I cannot stress enough how important has been the access to nature during this troubling times. Walking in the woods, a park, next to the water has been essential for my mental health. #mentalhealth #naturelover
And for those of you who think that it does not look very Spring like, it also looks like this! And no, the pink tree is not a cherry blossom. I've no clue what it is, so if anyone had a clue, please let me know! #Stockholm #Flowers https://t.co/1mf1l6roZu
Now, I need to get back to proposal writing, but I'll be back for a while around lunchtime! Stay safe everyone :)
@gudrun_lotze Haha no, there are multiple bridges, already two connect to the city centre. :) I don't need to cross a big stretch of water, thankfully ;)
@gudrun_lotze This is taken from one of the bridges I can use :) https://t.co/OPrvw1FiEW
@gudrun_lotze Yes indeed! And not all of them big enough for houses or at least something beyond the size of a summer cottage.
Hej hej! I am back for a while :) As I mentioned earlier, I am writing a grant proposal which basically needs to say that I've a great and novel project, that I'm the best for it and that's why they should give me financial support.
I've seen that some people think that academics have a very secure job. But whilst this might be the case for a few (not all) tenured positions, the rest of us are in the constant look for available positions, and even when you get one, we need to find a way to finance our work.
How much you depend on these grants, and how long your contracts are depend a lot on the institution, department, and country where you reside. #ecrchat #postdoclife
Therefore, something that becomes more and more evident that one of, if not the key, skill one needs as a scientist is that of writing. #academicwriting
Even when considering writing, a lot of focus (at least in my experience) is given to paper writing. Which, don't get me wrong, is indispensable, as this is how we are often evaluated. But if one wants to keep writing papers, then you need, blu tly put: money!
However, I was never offered a workshop on grant proposal writing. I have now managed to write one by looking at other people's proposals, and by getting feedback from. But I was lucky, many people do not have good mentors, for example.
Also, grant proposal writing is very different from paper writing. Yes, the science must be there, but it is more of a sales pitch, think of a Dragon's den or a Shark's tank. You need to sell your idea, that you're the right person, and have a coherent plan for the research.
This is just my first grant proposal, so I am sure it has many 'areas of opportunity', but it has deeply made me ponder on why I do what I do, which path I might want to take, and how being a researcher is never what you though it would be.
Which is why, I think that people coming from certain areas of industry or working at the interface might have a better chance at getting grants. As they have had to hone their communication skills. But this is just a thought.
What becomes to me ever more clear is that scientists, at their core, are communicators. We pass our lives writing about what we have done, presenting our work to our peers, or if one is into #scicomm to non-academics, or to scientists outside our area. #communication
We need to be versatile as we need to communicate these ideas to a variety of audiences, with different purposes, we need to be able to find the thread connecting it all to bring a coherent story.
I was once said that the science should speak by itself, in the context of getting prestige perhaps or grants. But I think it is up to us which voice we want to give to it. If it is secretive, mysterious, or if it is open. #scicomm #academicWriting
Yay! I have now submitted the proposal, will still need to proofread before the deadline, but for now it's good, and now I can attend my Swedish class! Busy day today!
@RKarsthof I am so glad this thread resonated with you! I think that the 'grant jargon' does not come naturally to many people, plus, it is very different from paper writing, and have to highlight your strengths, which doesn't come easy, especially during the early stages of a researcher.
@RKarsthof I'm hoping to reach that stage! But I also have the feeling that even later in your career it can be stressful. Perhaps you have developed better skills, but the stakes are still pretty high... Not to mention you need to keep coming up with ideas!
@gns6w3 To be fair, my brain is fried. It usually already is after 3h of Swedish class, but today I'm just spent!
Swedish class done!!! I am totally exhausted now, the emotional and work load of the day and past few weeks has been quite a lot. But tomorrow, after 2 PM, I can chill, my part is done (in terms of the grant proposal) and the wait begins.
Since I've just finish my Swedish class for today, I have been wondering how many languages do you all speak? Myself, 4. Not all of them fluidly, especially Swedish where I have very basic abilities.
Here is the poll!
In Science, we usually communicate in English, but more often than not, this is not our first language, sometimes not even our second! So whilst I think writing in proper English is important, I'm not particularly stressed about the use of correct but unusual words.
Also, some people, because of where their from, and/or family, are already multilingual from the beginning (if only I had had the chance!), and so, they have not necessarily experienced the learning of another language at a different stage in life.
My native language is Spanish, but I started learning English since I was 2 yo. Then, I started French at school when I was 15,and then restarted it during my 20s, but it was still easier as the I had learned the basics at school. But now, Swedish has proven harder.
@RKarsthof At least with paper writing, you might be able to get first hand experience during your PhD. Although I know this is not always the case.
@RKarsthof Actually, I brought this up because it came up in conversation with a friend who's by now applied to several grants. And he mentioned it got harder to think of new projects, also, as different grants or for different time spans.
@RKarsthof However, once you can afford the head space for it, or if you're already brilliant enough. I think that the key is having a long term vision and then viewing these projects as steps towards achieving this vision.
Have any of you had to learn a different language as an adult? What have your experiences been?
@RKarsthof I completely agree. I guess we start with smaller projects, and once at least a couple of them take root, we can start thinking of 'the bigger picture'. #ecrchat #postdoc
@RKarsthof And by the way, good luck with your proposal. I hope it's successful!!!
I myself have found it hard, partly because now I'm not as young, but also because the teaching and learning is in a completely different setting and environment.
Part of the difficulties of learning Swedish, even if I am living in Sweden, is that I have had to adapt to a new country and city, but most importantly, for my work I've needed to learn new concepts and develop new skills, and I admit that that has taken priority.
Not to mention that I find it really hard to pronounce! Nevertheless, I hope to keep improving, not only because of the advantages it poses, but because I really do love its musicality, and I find languages fascinating. They're always entwined with a country's history & culture.
@RKarsthof Thanks!
@FSchaufelberger Thanks a lot! :)
@craywand Well this is cool, seeing another liquid-liquid transition! :)
Cool! So most people speak at least 2 languages, which I find amazing! Especially if you're doing science in a different language than your own, and even more if that language has a different writing system than yours.
I'll take a look again tomorrow if anything has changed in the poll. But that's a wrap for me for today. Need to wind down with a good Terry Pratchett book, before visiting the land of The Sandman. Thanks for reading today!
Good morning sunshine! And indeed there's sunshine today, blue sky and all! Hope you've weather wherever you are :).
This morning, as one can resubmit as many times as needed before the deadline, I'm proofreading my proposal one last time to ensure that it is as typo free as possible. And in the afternoon, I will have my second meeting from my mentee from the Supernova Foundation @SF_mentoring
@ElAbdleb @SF_mentoring Thanks!
Actually, this mentoring foundation is really cool, it is meant to support women in Physics :). I was not sure that I would be able to be a mentor, but then, after some more reading. I realised that I could! After all, I've already done my PhD, outside of my own country!
The reason why I was unsure about whether I'd be able to be a mentor, besides a 'standard' imposter syndrome, was that I do not hold a Physics degree. So I guess it's time for me to tell you a bit more about myself.
And I've just realised that for some reason I said a meeting from, instead a meeting with! Epic fail! Sorry for this! I'm sure once I get a good night's rest my writing will improve!
So hi! I am a postdoc working at a Physics department, in the Chemical Physics division. Most of my collegues are pure Chemists or Physicists, and I, well I am a Food Technologist... Yes, you read that right!
I did my undergrad back in Mexico and afterwards I immediately started working in industry in a food additives company, in the applications lab. I worked mostly with thickeners, gelling agents, and sweeteners. It was fun as I worked with different products!
Whilst thoroughly enjoyable (I baked muffins, made yogurt, ice cream...) at some point I could not grow any more, and I did not fully like the types of positions I could get somewhere else. Plus I wanted to learn more, so I went to @UniversityLeeds for my MSc in Food Science.
@willrbrant1 I do think that it is a great thing! I think part of the bad rap it gets is because most of us, especially at the beginning, have no idea how to get started, and so, it's a hard process. But I can honestly say that even if I don't get the grant, I'm very happy to have done it!
So I moved to the UK, met wonderful people, and my curiosity got the best of me so I applied for PhDs. I got accepted to the @SOFI_CDT but also I got an offer for a PhD on the crystallisation of cocoa butter, also at @FoodSciLeeds with @megan_j_povey.
Due to a variety of reasons, visas, timing, funding, interests, I decided to go for the Leeds PhD, which also happened to be in collaboration with @NestleUKI #nestleyork. I mean, chocolate is always alluring right? (cocoa butter is the fat in chocolate)
And this is how my journey into X-rays began, as X-ray diffraction is the best way to identify cocoa butter crystals. More to come after my walk :)
If you've some questions about my road so far, post them here in the comments!
So back from my walk. The sun was shining, but my was it windy! https://t.co/MhPUwRqgL9
But before leaving, I was telling you about my road. I left of saying that I started my PhD on cocoa butter using X-ray diffraction, of which I didn't know anything about, except for the famous Photo 51 of DNA.
Soon I would learn the basics on small and wide angle X-ray scattering, along with the important role of @UniversityLeeds in the development of the technique!
Leeds, was one of the places where modern molecular biology was born as X-rays were used under Astbury to study natural fibres, like wool. As a side study, they started looking into DNA, and the first DNA image was taken by Florence Bell! But this line of work was set aside :(.
And it's in the honour of Astbury, that @UniversityLeeds has the @AstburyCentre for structural molecular biology.
But Astbury's work is not the only important thing in the history of X-rays and Leeds. Those of you who work in crystallography, or some X-ray diffraction scattering are acquainted with the Bragg equation, the Bragg peaks, etc.
And it is actually in Leeds where William Henry Bragg and his son performed their pioneering with that would lead to them earning the Nobel prize! And nowadays there is a new centre for materials research @BraggRoyceLeeds #xrays #crystallography.
*pioneering work that would lead..
If you want to learn more about this story, visit: https://t.co/MRG61h3XyZ and https://t.co/G2KnWlGuCU
@BraggRoyceLeeds I was so excited when I saw the plaques in the Chemistry Building!
@BraggRoyceLeeds That's amazing! At the end of my PhD I was a bit sad that I wouldn't get to see it finished. Once traveling is easier, I'll definitely need to go back and visit!
One ramen later, I'm back in front of the screen, but I'll soon have my meeting, so I'll be posting after that! Because of Covid safety, I sat outside, was I awfully cold? Yes! But that was not going to stop me XP https://t.co/eYx7WegYsf
@JoFeanelwa @BraggRoyceLeeds It is indeed quite amazing! But I think one of them was the experimentalist, and the other the theoretician, so maybe that's why it worked?
@JohannesBaller Hej! Not random at all, cycling is more than viable, an in fact very common here in Stockholm. I am sure you will enjoy your time here if you do come for your semester abroad :)
@xray_matt @BraggRoyceLeeds I think that it is not the original they used, but they do have at least an X-ray tube like the one the would have used. https://t.co/WAePga2xfI
@SF_mentoring Thanks a mill!
Back from my meeting, which was really good. So far I have found that these mentor meetings always leave me feeling happier, as they make me focus on the good things of life as a researcher :)
@SF_mentoring Thanks a lot!
So yes, after a brief detour towards the history of x-rays and Leeds, I can continue describing my road to my current position (I promise I will get there in the end!)
I said I did my Phd on cocoa butter, I was introduced to the world of X-rays, which is basically the world of invert space, under the great supervision of Michael Rappolt from @FoodSciLeeds. But there was another BIG suprise for me still.
I had now learned about lab-based X-rays, the kinds you can fit indoors (think of when you get an X-ray of your teeth, or a broken bone). But there are also these considerably larger X-ray facilities called synchrotrons! I knew about the linear accelerator in Mexico, and CERN...
But these were more to understand particle physics, little did I know that synchrotrons are large facilities where electrons are accelerated close to the speed of light, and then their path is bent by very powerful magnets. The electron loses energy and emits light.
So yes, we basically make the electrons work hard to get our lovely X-rays. #synchrotron #xrays
@JohannesBaller Thanks a lot!
I had no idea these things existed (Food Technologist remember?), but now, I was not only made aware of them, but because of the type of experiments I wanted to make, a lab-based source was not adecquate, so I had to apply for what we call "beamtime".
These facilities have the electrons running 24 h a day, and there are many researchers wanting to use these X-rays, so we need to make a case, write a proposal, asking for time to use the X-rays, the beam. If successfull, you get allocated a specific number of hours.
The first time applying @DiamondLightSou I was not successful, as I said, many people want the time. But the second time around we got the beamtime! Hurray! Although, mind you, we got 3 days full 72h non-stop. I think I only slept 3 h in total. Not ideal, but I was so excited!
I think I was running on pure adrenaline. But come on! I had never even imagined these things existed, and now I got to "play" with one. And so, I fired X-rays to cocoa butter.
Here is a magnet I believe. https://t.co/mlzPOMmVIH
https://t.co/ILjPLUKcXh
After this, I fell in love with X-ray science and new that I definitely wanted to continue working with them, though I knew it was definitely not guaranteed, especially as I had not worked with them for long, and because I only had one beamtime in my pocket...
So when time came around to look for postdocs, it was, as per usual, stressful. I applied to many, got no as an answer for some, got no answer from others, I even got replies of "the position will not be filled in for now" after a year of my applicaition!
But then, this beautiful, amazing advert came around. I literally found it by typing the keywords: postdoc, pressure, x-rays. Which was essentially what I was looking for.
It sounded magical, X-rays, water, synchrotrons, XFELs (wait what?). But the desired profile did not match mine, it sounded pretty much like they wanted a Physicist. I consulted with so many people. And I was told time and time again, they want a Physicist.
Eventually someone told me, apply for it, you've got nothing to lose (except my and their time I thought), but then, Arwen Tyler @NotAnElf gave me the best advice: if you really want this thing but you are so worried, write to the PI, say who you are and why you're interested.
Then you can ask if you should apply, or better save their time... I thought this sounded very reasonable. And this is exactly what I did. I was petrified, but it was worth a shot. I really wanted the position!
To my surprise I got an immediate reply: Absolutely, fill in the application online and give us your references! I was extatic, and immediately filled it in and submitted it. On the day of the application deadline, I got an email inviting me for an interview.
@grumpymaterial Do not panic! Define bien tus objetivos, y estáte preparado para que estos cambien o se refinen con el tiempo. Conforme escribas, todo se irá aclarando. Ah! Y lee tu proposal en voz alta. Encuentras mil errores de esa forma.
@Maryam_Eslami If you have not met them before, yes. Introduce your lovely amazing self, and go for it. I have not done it myself, at least not for a fellowship, but I have made connections this way.
The interview would have to wait for another month, as I did not have my passport with me due to visa processing, but when I finally came to Stockholm, I was received by Katrin Amann-Winkel, who immediately made me feel at ease. I also met the rest of the experimental team.
After lunch, they had a meeting, so I had to wait for a while, and talk to one of the theoreticians. And when I went back to the office of the PI (Anders Nilsson), he bluntly told me: "We want to hire you" I was overwhelmed. First time in my life I was rendered speecheless.
Eventually I recovered, things were discussed, arrangements were made. And amazingly enough, I was invited to fly with them the following week to South Korea to the XFEL @PohangLights. Trial by fire, spending over 12 h a day with people I didn't quite know.
But it worked beautifully, they were incredibly welcoming and supporting, and I was able to get involved with the experiment. Not to mention, I got to taste Korean food, which I have to admit was to spicy for me!
Here are a few pictures! https://t.co/5ZQf0J0PES
@Maryam_Eslami Just remember that you literally have nothing to lose, but everything to gain ;)
I have now mentioned that they invited me to join them to an XFEL, but what is this? Is this just some other version of a synchrotron?
So the first thing that is different between the XFEL and a synchrotron is their shape. In a synchtrotron, you first accelerate electrons (in a linear accelerator) and then you put them in the storange ring. Ring being the key thing. Whilst an XFEL is "just" a linear accelerator.
The XFELs can be from a bit more one km one, like the one in Korea, or over 3 km long, like that in Germany (@EuropeanXFEL ) or the one in Standford (@SLAClab).
In XFELs you accelerate the electrons to high energies, then they go and wiggle around through magnets (called undulators), where they emit X-ray radiation. Importantly, the radiation keeps getting amplified here, and the electrons organise themselves into thin disks, leading to
X-ray flashes!
So here you do not really get a continuous stream of radiation, but rather pulses. These pulses are then controlled in spacing and duration, allowing us to access molecular processes and structures never seen before. I will actually tell you later how we have used them.
@realscientists @chabis_ch I've had to learn Python on the go, and know very little of Matlab.
I'm signing off for today, but let me know what you would like to hear about first (you'll hear about both so don't worry), cocoa butter or ice and water?
Cocoa buter is the winner then! Expect then to hear a bit more on what I learned about it during my PhD :) I will not be tweeting as much as yesterday, because, you know, work. But I hope you won't be disappointed and enjoy the science :).
@chembiogeochem I think I didn't say what XFEL stands for: X-ray fee electron laser! Here's a nice video from @SLAClab https://t.co/8cDO6GQoc9 if you want to know a bit more! #XFEL #XRays
First golden nugget, or chocolate nugget? Did you know that cocoa butter is the one responsible of that beautiful gloss, the crack when you bite a bar, and the amazing smooth velvety sensation that fills your mouth when you eat chocolate? https://t.co/pB55etgMTK
However, you might also have encountered a chocolate that has an off-white colour on the top, chocolate that has lost its luster, especially if you've been carrying it around and it has been melting and cooling down again.
So this means that just having cocoa butter is not the only thing we need.
[admin] "Melting Ice with Very Expensive Lasers" Extended conversation with @M_LaddParada is out now. Chekkit 🥳👇🎙️ https://t.co/uEoHw5JaFF
And mind you, cocoa butter is the fat naturally found in the cacao beans, from which chocolate is made. Now, whether you think that white chocolate is chocolate or not, that is a different story. But for sure, to call it chocolate, it needs that amazing cocoa butter.
@realscientists This links with what I was talking about yesterday ! :D
Thing is, cocoa butter, fats, when solid, they form crystals! Yes, crystals are not only minerals, like the ones you see for healing, meditating and stuff...
And since it is not straightforward for molecules to arrange themselves into a nice periodic structure that has local and long-range order, we have different types of crystalline forms of cocoa butter. We call this property "polymorphism" so multiple forms.
Some people call them with roman numerals from I up to VI, and then, we have the greek letters sub-alpha or gamma, alpha, beta prime (III and IV) and beta (V and VI) in order of increasing stability (melting temperature!).
So yeah, even scientists can't agree on how to name things...
But anyways, of all of these crystals we want, not crystal VI, but crystal V! Why? Crystal VI is too hard, has a higher melting point, but Crystal V is the best for a good sensory experience, it is the one that melts at body temperature.
So how do we get the right crystal? By using a process called tempering, which people in metallurgy might be familiar with! Although also, foodies, chocolate aficionados and the like.
I will come back later with more chocolatey goodness, okay more cocoa butter goodnes, but it sounds so much better to say chocolate...
And before you ask, no I was not tempted to eat it! I have never been inclined in eating pure fat on its own.
[admin] You can now listen to Marjorie's full length interview on the podcast #UnderTheMicroscope on YouTube https://t.co/Jt855aokiI https://t.co/C7ItZusZNx
@gns6w3 LOL, when thinking of the crystal form, I would not look at SAXS, but at the WAXS, that's where you find the gold! But, if you are interested in SAXS, I recommend you check out our two papers! https://t.co/9x9nNDKXoX and https://t.co/jkRhJwwYbW
@gns6w3 That sounds trying... I would say that a 'pure' white chocolate would be vegan, as it would only contain cocoa butter. If it is vegan, they might have added other vegetable fats, which never give the same profile as cocoa butter, or as cocoa butter with milk. And then low sugar.
@gns6w3 Low sugar can be that they really added very little sugar and that's all, or that they used other sweeteners and bulk agents, which again, will give you a different sensory profile.
@gns6w3 For bulking agents, they often use polyols like erythritol (also found in sugar free gum). And they can give a cooling sensation, though chocolate already gives you that simply because the moment it gets into your mouth, it takes up heat to melt.
@gns6w3 Also, since you are into neutrons (I have always wanted to do neutrons! But due to life have never managed...) there is this very nice paper from @Helen_E_MC et al. https://t.co/ohqyXxLS6M
@gns6w3 @Helen_E_MC Actually, if you do neutron scattering of fats, I want in! (sorry for shamelessly putting myself forward, but I am really interested in learning!)
@gns6w3 Aha! Just like the Anton Paar we had (or rather they have) at Leeds! :)
@gns6w3 Yeah... Just having those darn sugar crystals bring so much noise in! Unless you want to look at the sugar of course!
@gns6w3 Haha, rather I think this is where Physicists and Food Scientists should work together ;) the knowledge is complementary.
@gns6w3 @ILLGrenoble Cool!
@gns6w3 @Helen_E_MC They are pretty cool! The fact that you can measure things in femto and in some cases even attoseconds is impressive...
@gns6w3 @Helen_E_MC Yeah, I mean especially the attosecond science is still under development, but here's a 'spooktroscopy' example. https://t.co/QoMzeb96Kx
I left off saying that to get the right crystal we need to temper the chocolate. But how does this process look? Well basically it is a temperature game.
You first melt your chocolate (depending on the type, the temperature, being the highest for dark and the lowest for white), and you keep it there for enough time that all, or most of the crystals disappear and become liquid.
Then, you cool it down carefully to roughly 27 °C (again, lower for milk and white), so that the beta prime and beta crystals form. If you go lower, lots of alpha, unstable crystals will form.
And finally, you want to get rid of the beta prime crystals, and only leave the beautiful beta V. For this, you can take advantage of their different thermal stability. So you heat your chocolate to 30/32 °C, thus melting the beta prime, and leaving only the beta V.
You can then pour your chocolate into moulds and let it set! If it has been well tempered, the chocolate will contract, making extraction of the moulds very simple. Otherwise, you will have a hard time taking out, unless you heat your mold and melt it all again. #chocolate https://t.co/wzfcgYV3AN
Now, if you have done tempering at home or in a cooking class, this might not be the method you have followed, but rather, you might have added some shavings of chocolate, to your molten mass. This method is called seeding.
Basically those chocolate shavings serve as "seeds" from which beta V crystals can grow. https://t.co/ejP7VJHCnf
It is really convenient for very small batches, but not so much in industry because cocoa butter really likes being in the most stable forms (The betas! For once beta means better than the alpha...), so crystallisation tends to happen so fast, and grows like a monster...
You can imagine it gets then really hard to pump the chocolate into the moulds for bon bons and bars...
@gcouprie Exactly! It is essentially the same :) Each type of crystal has a different melting point starting from the sub-alpha to the beta VI (16 to a bit over 36). So you first melt to a high enough temperature than even the most stubborn beta VI will melt. Like a clean slate.
@gcouprie The first cooling will lead to the crystallisation of cocoa butter, but you cool it to a temperature above the melting point of the sub-alpha and alpha. And you heat again to melt any beta prime, but keep the beta.
@gcouprie Do you mean in chocolate? Or elsewhere?
@gcouprie Usually you are always looking for the beta five. So this is the one temperature treatment you use. You really do not want any other form as they melt too fast, or feel waxy in the mouth.
@gcouprie I believe tempering is not so important when you are doing chocolate sculptures. Then you are not looking for a glossy fragile structure, but rather something that you can shape.
So one of the things that I was interested in was if the most frequently used temperature (60 °C) was ideal or if you need to heat it more (above 80 °C). Note, that a higher temperature in chocolate itself is not advisable due to the interactions with other ingredients.
What I observed and reported in my thesis was that the temperature at which you melted cocoa butter, before you cooled it down, did affect the order in which the different crystal forms would appear. So by heating it to a higher temperature, it would take longer to crystallise...
But the transformations were not affected, actually there was a hint that transformation to the beta-V might be accelerated. But this was pure cocoa butter. And you always have something else in chocolate...
Here is an image from @compoundchem on the different crystal forms of cocoa butter. https://t.co/26Q6kEs3iY
As to why it would crystallise faster if I first melted at 60 rather than 100 °C? It is hard to tell, I did check for oxidation, but my cocoa butter was stable for a few solid hours before degrading...
The trouble with working with natural fats is that they are not only made of one component, but rather by a multitude of them!
Cocoa butter, as well as most other fasts and oils, is composed by molecules called triglycerides, which are three (hence the tri) fatty acids (heard of omega 3, or palmitic acid?) that are joined together by a molecule called glycerol (you guessed it, glyceride comes from it)
Now these triglycerides, or more correctly triacylglycerols can have different fatty acids, attached in different order. And these fatty acids can be all straight, or have kinks because of two atoms sharing a double bond.
Cocoa butter has many different triglycerides (let's call them TAGs). OK, not as many as milk fat... but amongst these, it's main ones are the ones I, and others, like calling SOS, POP, and POS. So easy to remember...
The S (Stearic) and the P (palmitic) fatty acids are the straight chains, and the only difference between them is that one is shorter than the other, so they get along together pretty well when they are closely packed in the crystals.
Whereas, the O (oleic acid) has an insaturation, a kink. So that kink, unless it is next to another kink that gives it space (kinda like two spoons), it is unhappy, because then it is sitting too close to another atom...
@mkolsek Perhaps you are tempted now to have some chocolate? Would be a nice pick-me-up for a Wednesday...
So yeah, those oleic acids like spooning. https://t.co/NtHix5YnuU
This is what drives the different stabilities in the different crystal forms. In the less stable phases, they arrange in what we call a 2 L phase, so the length of the layer of the crystal is that of two fatty acid chains. This means that some kinks will be unhappy.
You could in very broad terms say this is because they are in a hurry to get into a packed solid structure, so they do not get into the most perfect packing.
After some time though, or if you crystallise at a higher temperature and have the patience to wait a bit more, like in tempering, the packing changes into a 3L structure. And yes, this means that the length of the crystal layer is of 3 fatty acid chains.
To achieve this, all, or most, of the oleic acid chains get on a single line, separating themselves from the rest.
Tomorrow I'll most likely be talking about ice so stay tuned if you need a fresh drink! I will now leave for today, but first, another poll, or rather two! First : Did you learn something new today?
The second one is, what did you enjoy the most?
Yay! Super happy to see that most of you learned something new yesterday, and if you didn't, I hope you still enjoyed it :). Also, for the few who voted, you preferred cocoa butter, which I I guess is no surprise, I mean, most people loves chocolate!
A sneak peak to today's topic. #ice #popcorn #amorphous #phase transition #polyamorphism https://t.co/3KWmcCMpnb
You might have guessed from my tweets yesterday, and from the hashtags I used that the thing you are seeing is ice, as it transform in yet another type of ice!
Even though you might thing ice very well, especially since freezers came into existence it became more common place even in warmer countries, ice is not as simple as the ice cubes that you put in your preferred summer beverage. https://t.co/YYoVmgSUy4
There are may different types of ice! In fact, in terms of "crystalline ice" so yes, the one with short and long-distance structure and order, there were 18 forms known, and recently the structure of ice XIX was elucidated! https://t.co/U4kmC2tQws
For those of you wanting to read the paper: https://t.co/xsc4haRwvb
So for those of you who had heard about ice-nine from "Cat's cradle" let me tell you that it actually exists! It just does not turn all liquid water into ice, it is actually only stable at 140 K and at higher pressures... So don't panic! https://t.co/WTTDmr2IbX
What you see in the GIF above is not the terrrible ice-nine, but your usual ice (ice I) coming into contact with supercooled water. Supercooled means that it has been chilled to a temperature below it's melting point (0 °C), this is achieved by having ultrapure water.
But, even if you manage to cool it down so much, it does prefer to be in the most stable phase under those conditions: ice, which is why the moment it gets into contact with the ice cube, it crystallises. It's as if it had just been waiting for the instructions to arrange itself.
More to come after lunch! And given how sunny it is, perhaps I can treat myself to some icecream... https://t.co/q4dM1oiTQL
But why should we care about supercooled water? Besides the obvious (supercool remember? * sorry not sorry *).
It turns out that water is a pretty unusual liquid, yes, it is ubiquitous on our planet, but it does not behave as normal liquids should! #strangewater #water #anomalous. For example, your usual water cubes float in liquid water, whereas a normal liquid sinks, such as methanol! https://t.co/MCOUJ2WQFI
If one fits a power law to the thermodynamic properties (density, compressibility, heat capacity...) of water, they all seem to diverge at a temperature of 228 K. (https://t.co/ZwdvFhCWVI)
But what is happening here? There has been several hypothesis, supported by theory and molecular simulations, but one of these is that water is in fact two liquids, a high-density one, and a low-density one. At very low temperatures you would be able to see the transition.
*hypotheses
Not only this but as one approaches the temperature mentioned before, at positive pressures, one reaches a critical point (LLCP) where the two liquids coexist but are fluctuating constantly. These density fluctuations are thought to then be the origin of the anomalous properties.
So far, it had not been possible to study this region experimentally, as crystallisation (ice formation) happens incredibly fast, which is why this region has been called "no man's land", it has been unchartered territory for a long time.
But I have been lucky enough to have been part of the team that has managed to go past the icy wall, to tread where no one had (am I being too proud of the achievement of the team?). And all thanks to the amazing XFELs!
We managed to observe how the high-density liquid transformed into the low density one BEFORE ice formation started! And this is indeed very cool! https://t.co/hcloL1WFZc
Here is the link to the paper: https://t.co/3NiyPMwWpB
@CandiSpillard LOL, there is an ice IX! But it was not discovered after Cat's Cradle ;)
@CandiSpillard Unless you literally meant time-wise, in which case, I think the novel came out in 1963 and the ice was discovered in 1968, but I cannot swear by it.
Now I have talked about supercooled water, next stop: the popcorn ice! https://t.co/bGxAT41non
@CandiSpillard All they say, I am afraid is: "...the designation "ice IX" is proposed. This designation has already been used by Vonnegut for a phase of ice, but since it was a fictional phase, the name is not pre-empted." https://t.co/L9R01lniln
@yolicomoelrio Awww gracias! https://t.co/UoSxDpwvtk
Sorry I went very quiet, but my meeting became longer than anticipated! I hope you still want to know a tid-bit about amorphous ices! https://t.co/Zr0e1TLfOD
In the cropped image you can see above, you will see that it says "amorphous ices" and you might wonder why, as I have been talking about supercooled water so far.
To get to the supercooled regime, you can come from the top (higher temp) or the bottom (lower temp). If you come from the top, at least in our group, we tend to use droplets under vacuum, which will then cool down by evaporative cooling, kinda like how sweat cools you down.
But we have "only" managed to go down to 227 K... https://t.co/ZuWmENK3sO
That is relatively straightforward to understand, you come from liquid water and you cool it, but what lurks in the depths of the phase diagram of water, at really low temperatures and higher pressures? Yup, amorphous ices.
They were first discovered in the 80s by Mishima, and they can be formed in the lab by crushing crystalline ice, and then by annealing (like maturing) at specific temperatures and pressure you can get different types.
We primarily have two: low-density amorphous ice (LDA) and high-density amorphous ice (HDA), I know, not super original, but very descriptive, which is what we need.
It is easy then to suspect that they might relate to the high- and low-density liquids (HDL and LDL). This is indeed then how we approach things from the bottom up, and is what we did in the Science paper.
We basically had our grid with HDA and then fired a lase to increase its temperature really fast, and then we shot the ice with X-rays to probe it and take a "picture" of it. We took X-rays at different times after we "pumped" the ice with the laser. This is known as "pump-probe"
Between our previous knowledge (both from within the group and literature), and through simulations, we could ascertain that the HDA had transformed into HDL, and then to LDL, and finally crystalline ice.
Now you might wonder why all this is ultrafast! As I said before, crystallisation happens crazy fast, with this experiment we saw it begins at around 1 to 3 microseconds at 205 K, so we if take our sweet time to heat and measure, we miss this transition.
You might think that this is really nice and pretty, but it is all "in the lab" and that you might only care about "real" ice (so ice I). The thing is, the most common ice in our Universe is not ice I, but it seems that it would be something more like our LDA.
You heard that right, amorphous ice is prevalent in our Universe, it is present in interstellar dust. If you want to get closer to our planet, it seems that before ice I forms in clouds, we first have amorphous ice.
That is all from me for today, but I will leave you once more with a poll. Now that you learned about amorphous ices: HDA and LDA, what do you think you are seeing in the small video I posted this morning?
@realscientists @jguokelly This is how it should always be explained! Cats make everything better...😅
@ElliotMiles8 Simply put, I'd do it all over again!
Good day everyone! (In case you are in a different time zone). The video shows the HDA turning into LDA, it pops like popcorn as the density decreases, so the molecules stop being so packed together. Eventually, it does transform into crystalline ice, but we don't see it...
...because the densities of LDA and ice I are quite similar.
For those of you who are more interested in amorphous ices, I recommend you watching Katrin Amann-Winkel's public lecture! #ice #water #xrays I work with her here at @Fysikum at @Stockholm_Uni https://t.co/YHXji2xirK
For a bit more water-focused talk, you can take a look at this somewhat old lecture from Anders Nilsson: https://t.co/CIV4eGof5Y
Och om du pratar Svenska, du kan titta på Anders Nilssons öppen föreläsning! Också från @Stockholms_univ https://t.co/ftIYUStPXH
Hey everyone! This morning has been dedicated to literature search, and starting to sort my references. I do use a reference manager, but somehow some stuff has not been added properly, or I have added it more than once... I will have to finish doing that some other time.
I thought I would talk to you a little bit about how COVID 19 has affected my research. At least in terms of the practicalities of it. I do not want to focus on the "doom and gloom", not take seriousness out of it, but because there is a lot of bad stuff to read in the news.
Of course, it has affected me mentally, yes even if I have been in "lockdown-free" Sweden. I am not one to be able to carry on when the whole planet is in pain, and especially when far away from my family and friends.
But focusing only on this, only makes things harder, plus, I am sure that lots of you know how hard it has been, and still is.
The main way in which COVID 19 has affected my research are beamtimes! Yes, they have been limited now because of the type of work I do. I know people have not been able to access their labs in many places, but here, sometimes I wish I would do more lab-based stuff...
Some of the X-ray facilities have closed for different periods of time. And when reopening, they have several restrictions, on top of the traveling restrictions from that country. This makes it hard for us....
There are some groups and teams that have been able to pursue their experiments, sometimes because they are within the same country so things like quarantine are not needed, or their experiments can and have been adapted for "online" or "distance" beamtimes.
Some experiments might be more routine-like and are already customarily done remotely, by sending the samples in, but others have required a vast effort from both the facilities and the user's to perform the experiment!
But some of us have setups and samples that cannot be adapted to this kind of beamtimes. Our setups are custom-made, our samples need to be AT ALL TIMES under liquid nitrogen, and are awfully fragile! So, unfortunately, we are only able to have beamtimes if travelling is possible
Of course, flying to Germany is indeed feasible, but how affordable is it to stay in isolation for two full weeks, plus the week of the experiment? Not that much, especially if we are talking of a team of at least 4 people.
We still managed to have a beamtime last year @desynews !!! :D This was end of August, when cases had dropped across Europe. Part of the team drove up there, and we were limited to four people total, max two at a time, and mask-wearing was, of course, a must.
All of these facilities, just like everything else, has had to adapt. First delaying beamtimes, in the hopes of a soon resolution, but now a complete rescheduling of beamtimes as we do not know for how long COVID-19 is here to stay.
I must say, that the light sources-as we call them-have done a fantastic effort, not only to adapt to the ever-changing circumstances but also, they have been incredibly important for research about COVID19: https://t.co/3SbjU2lSTT #COVID19 @lightsources So a big shoutout to them
Here's Aigerim (PhD student) and yours truly :) https://t.co/ujxRzQPbe8
And in case you are wondering how PETRA III @desynews looks like a bit, plus a nice picture of work under liquid nitrogen. #cryowork #xrayscience https://t.co/HIOqM692xO
[admin] Our newest video looks back and celebrates our curators from the first quarter of 2021 - thanks again to @AnnaPloszajski, @Olu_GH, @OHJMustonen, @AnnaPiras19, @LaiaDelCa, @nanouschi, @rkarsthof & @ElAbdleb! All interviews are still on YouTube. https://t.co/ipAv5Pc9zp
@gns6w3 I currently use Mendeley because it is free, and had an add-on for different browsers, but during my PhD I used endnote as the uni paid for the license.
@gns6w3 @desynews I know, I did participate in a partly remote beamtime at the XFEL, but even if we used slack, we were having meetings, and even remote access to the screens, it was not the same. But good enough.
@gns6w3 @desynews About the DESY beamtime, yeah, it was hard work, but we got so much data that now I am 'dreading' the data analysis. From the preliminary stuff we did on-site, it also looks like it's not only a lot but also quite good!
@gns6w3 I actually wanted to give LaTeX a go for my thesis, but neither of my supervisors were comfortable with it, so it was easier using Word. And even now, in my group, I think the experimentalists mostly use Word. But any tips on how to get started are welcome!
@gns6w3 @overleaf Cool beans! Thank you :)
Quick tweet, I have just been made aware of "danceroom spectroscopy" Check it out! https://t.co/CC3d3XBI2H @danceSpec An amazing example of interactive Sci-Art #scicomm #sciart
I did post a video on XFELs, but here is one on synchrotrons, particularly, Diamond in the UK :) https://t.co/5BPffbDZpb
@lightsources We're all in this together! 😊
@gns6w3 @danceSpec @BristolChem @BristolUni Totally! A colleague of mine showed it to us at our online afternoon coffee.
@FSchaufelberger Congrats! Be prepared for lots of sunshine hehe. Stockholm is beautiful in the summer!
Morning everyone!!! This weekend I wanted to take you with me on a walk around Stockholm, but unfortunately I have been in contact with someone who tested positive for covid (they're OK) , so staying at home for now (I'm OK)
I will then post stuff from pictures I have taken before, but also, if you want to ask me any questions please do!
First off we have pictures of the lake at Haga Parken! This is to the north of the city centre, you can walk there, or for a faster way, you can bike :) This was a great place last spring to see baby swans, ducklings and other baby birds :). #loveStockholm #water #lake https://t.co/RQQPlknkBe
NOT a picture of Stockholm, but as to how I'm entertaining myself today. Sorry for the change of content! I will definitely come back later with more Stockholm pictures, but what you can gather from this is that I also love baking! :) https://t.co/NuLJ8IQlIk
Other hobbies I have or had before COVID? Lindy hop and yoga! Lindy hop always gives me such an energy boost! https://t.co/HB9NcJLLgJ
Here is the result :) #saturdaybaking #baking https://t.co/ZxqXxowx15
For those of you who admire sculpture, Stockholm is definitely not lacking :) #sculpture #Stockholm https://t.co/niW8iFrfXR
Not only can you find your usual 'city sculptures' but annually in Djurgården there's an outdoor exhibit, and there's even a sculpture park: Millesgården #djurgarden #millesgarden https://t.co/6mDx2uf0sc
Millesgården is indeed a bit far from the city centre (in one of the islands), but you can get there very easily by public transport, or if you want, biking is an option. Djurgården, however, is a stone throw away from the station, which I find amazing. This island also hosts...
Skånsen, an outdoor museum, the Vasa museum (amazingly preserved boat), the ABBA Museum, etc and to be fair, the museums are a very very tiny part of the island... I'm so glad how easy it is to reach a green area in Stockholm!
And in case you're wondering how the place I work in looks like... Here are a few picture of AlbaNova University Centrum, which hosts @fysikum, as well as other departments from Stockholm uni and KTH. https://t.co/Za7cYMBiFZ
One of the cool things of working here is that it's so close to the lake I showed you earlier! So great for summer days late evening walks!
I know this is a bad, but intriguing picture, and I do not know what the person is moving. But it's the only picture I could find of what I like to call "the Department of Mysteries" (yes #Harrypotterfan). Basically, our lab is in the basement, has no windows, & one can get lost. https://t.co/QC4LDpq9T8
And you even get to see really cool stuff like this, although this is not in the basement... https://t.co/7kvOXEzdXy
@tiantian_s I don't think anyone calls it like that except myself XP
I hope you enjoy the rest of your Saturday! I shall leave you with some flower pictures now that Spring is finally (properly) here in Stockholm :) https://t.co/lYeJh3aUfX
Good morning sunshine! Since I cannot show you the actual sunshine today, I thought I'd share the one from last summer. This is in one of the nature reserves in Stockholm! #loveStockholm #naturreservat #naturelover https://t.co/BrHubrkfva
@DrStephMcCready @Helen_E_MC @DouganGroup maybe something to consider? :)
Between the long computer hours because of grant proposal writing, and this week's quarantine, I've developed a lovely back/sciatica pain. I'm no stranger to back pain, as I've had lower back problems since I was 15... #backpain
And this pain makes sense, bad posture, non-ergonomic chairs, at my place I've no desk, and then there's the lack of movement. Of course having made a short exercise program would've made sense, but my mind was elsewhere engaged. Which means that better planning is due next time!
This (and ofc the covid scare) has actually made me reflect on, of course, health, how precious it is... Last year, as COVID started, COVID was not my only health concern, the previous November I had tripped on the stairs and hit my knee. Not broken, just damaged the nerves.
I was given anti-inflammatories, asked to not walk (yay for a month in bed...) things got better, but then I flew from Mexico to Sweden and all my efforts went down the drain... In the end, after some physiotherapy, I can walk more than 10 min now without pain or my knee swelling
But it's still incredibly weak. I'm trying to strengthen it, but it's not easy. Also, there's stuff that still isn't right, if I sit or stand for long periods of time, it still gets funny. So yeah, seems the damage is here to stay. #kneeproblems
But as aware as I was always tried to be for other people's predicaments, it's never the same as actually living through them. The fact that I could not dance, run, or even walk for long periods of time as I used, to took a big tall on my mental health. I lost motivation.
Then, why not, came COVID and everything it has brought to us. I can honestly say I was struggling a lot, I was especially worried about my family. Also, after only a year in Stockholm, I didn't quite have a strong support network, my close friends are scattered across the globe.
But somehow, I ploughed through it, and it's brought me closer to the few friends that I had managed to make in that year. Also, one eventually learns how to live in this madness, although it's not smooth sailing all the time ofc.
I must say there was one cool thing amongst all the bad stuff with my knee! For the airport, as I had a very short connection in Amsterdam, I requested help. This was seriously awesome....
To get me off the plane, they have this amazing lift-cars, so basically it looks like a regular van but it has this supports to lift it up to the airplane door. So they basically put me on the wheelchair, pushed me inside the van thing, and down we went. It was great fun!
Once at the airport, I also met a lovely man who pushed me in my chair around the airport. He told me he used to have a shop, but he felt he was fooling people by selling for a higher price than to what he bought the goods for.
So he closed it down and got the job he now had @Schiphol Airport. And he said he loved it, because he was helping others, and he also got to meet people from around the world. And that for him was more important. Sadly, I did not get his name. But he was inspiring.
I guess what I learned from him, from what we've all been through is that there's no time like the present. Make a priority of that or who is most important to you, and if you're sacrificing something to achieve a goal, make sure that it's worth it.
But most importantly, be kind to others. We're all going through hard times, and there's no need to make it harder. #kindness
I'm super happy that today "The great moose hike" starts streaming! This is slow TV at its best. https://t.co/qSX40N0oGX #denstoraälgvandringen so if you're missing nature and would like to have as a background Swedish forests, be sure to follow it every day: :)
I had no idea this existed until last year, and I very much enjoyed it. All day I could surround myself with nature sounds, and it was all made more joyous with the occasional sighting of a moose or some other cute animal! If it's not possible to travel in body, at least in mind!
It is time for me to sign off. Thank you everyone for this week, especially to the team behind the account. I've had a great time and I hope that you enjoyed it as much as I did. You're more than welcome to follow me @M_LaddParada though I don't tweet half as much. 🙈
Remember to be kind, that cocoa butter is tempered like metals, that ice ix exists, and whatever else you thought was cool or resonated with you this week :). Thanks again! Hope you enjoy your Sunday! https://t.co/B56dJwgRO9
[admin] Huge thank you to @M_LaddParada for an amazing week of science and showing us around Stockholm. 🥳 Do give her a follow! Podcasts ft. Marjorie 👇 Short - https://t.co/YcN1L2qms9 Long - https://t.co/uEoHw5rzh5 https://t.co/diQNdbquNZ
Andrew Pun
[admin] "The Magic of Nanocrystals" Please welcome @AndrewBPun for a wonderful week of science and listen to the podcast to know what is coming your way this week 🎙️👇 https://t.co/37JRhyz28G
Hi everyone! My name is Andrew, I'm a postdoc working @ETH_en for @NorrisOMEL I'm looking forward to curating this account for a week! Today I'll be sharing my career path so far, and how I ended up working and living in Zürich
@ETH_en @NorrisOMEL Both of my parents are from Peru 🇵🇪 but I was born in a town called Folsom. It's a small town in Northern California. And just about the only thing we're known for is a prison that Johnny Cash made famous. https://t.co/kJU9p5OiMu
I attended @UCB_Chemistry for my undergraduate. During my second year I started working at the @molecularfndry for Dr. Yi Liu, and this is how I first got interested in nanoscience
The molecular foundry is a nanoscience center located in the Berkeley hills in this cool cantilever shaped building. Come for the science but stay for the incredible view of the bay area https://t.co/xZNX0NPaAb
After 22 years in California, I figured it was time for a change, and I headed across the country for grad school at @ChemColumbia where I worked with @SomosCampos @SoyLuisCampos
I was lucky to work with many great scientists while I was there, including (but not limited) to @CongreveLab @RovisGroup @XYZ_Columbia And just like my undergrad, there was a great view from the office https://t.co/SlXftz3TWR
During my time in grad school, I was even able to spend some time in the Netherlands, working at @_amolf for @brunoehrler for one summer
After finishing my PhD at Columbia, I started a postdoc with @NorrisOMEL where I currently am. Thankfully, with another great office view. Picture stolen from my officemate @nanouschi https://t.co/nAodcyW14n
Working in science has let me live all over the world, and experience all sorts of places and things I never would've been able to without it. For example, today is actually a holiday in Zürich. Happy Sechseläuten everyone! https://t.co/5aXBYKvFWI
@MilonHo13427034 @ETH_en @NorrisOMEL Thanks for the question Milon! It's definitely different. Some things are much better here, like public transit and health insurance. But I do miss things from home, mostly food/family/friends. Still, Zürich is an amazing place to live and I'm happy I moved here
Today I thought I'd take some time to talk about the research group I work in @NorrisOMEL. Even though we're in the mechanical engineering department @eth_dmavt we do a wide scope of science covering the fields of chemistry, physics, and engineering
Our labs are located at ETH Zentrum, in the heart of Zürich. Here we have two main labs, a wet lab upstairs (the one with a big hole in the middle of it) and a laser lab downstairs https://t.co/Uuu572j7YN
Being a chemist, I spend most of my time upstairs, where I work with students and other postdocs on nanocrystal synthesis. But we're equipped to do all sorts of work in the wet lab, like in this picture where I convinced @AlexCHernandezO to try some organic chemistry https://t.co/YupwH3PDpQ
Being a very multidisciplinary group, we work on many varied topics. I've learned a lot of new things being in this group, although I'll admit I still sometimes get lost in group meetings when someone talks about optics experiments that are far from chemistry
Just looking at OMELs recent publications you can see the breadth of work we do under the umbrella of nanoscience, ranging from phase change materials (https://t.co/tb0lpDsSsj) to optical Fourier surfaces (https://t.co/D1SMzpIQuT)
Tomorrow I'll talk about my research in the lab, focusing on the synthesis of semiconductor nanocrystals. In the meantime I'll leave you all with everyone's favorite part about nanocrystal research: Pictures of glowy stuff (plenty more to come this #fluorescencefriday) https://t.co/b0iT8ZA3i9
[admin] "The Magic of Nanocrystals" Extended conversation with the amazing @AndrewBPun is out now - https://t.co/4UXDp2XSVk
Here in Zurich with @NorrisOMEL I work on semiconductor nanocrystals. Because they're so small, these nanometer-sized crystals have properties that are dependent on their size and shape.
The most well known manifestation of this is that larger particles absorb/emit longer wavelength light. In this picture by Stefan Meyer, all these vials are filled with the same material, CdSe nanocrystals, but with different shapes sizes giving them different colors. https://t.co/qljtx7HNx5
Working with my PI David is a great because he's knows so much about nanocrystals. In fact, he's literally been studying them since before I was born! For example this project he worked on in the 90s really made controlled nanocrystal synthesis possible: https://t.co/V2ghUTIHgc
Specifically I work on magic-sized nanocrystals. These grow via discrete jumps in size, rather than the continuous growth seen in conventional nanocrystals https://t.co/juKKrqqDZn
I actually first heard about these magic-sized nanocrystals when I was a grad student in Columbia. @brandicossairt and @theowenlab did a lot of great work in this field some years back. https://t.co/DZSoP3R74m
One of the big issues with nanocrystal synthesis is a distribution of particle sizes. The stepwise growth of magic-sized nanocrystals could help us get around this, giving us batches of nanocrystals with more uniform sizes and properties
Sergio and @AniketMule93 recently showed that magic-sized nanocrystals are tetrahedra that grow layer-by-layer. Only perfect tetrahedra exist since they're local energy minima. And this is the reason for the stepwise growth we see. https://t.co/PhXuUl3ehL
Even though they have all these potential benefits over traditional nanocrystals, magic-sized nanocrystals have a lot of drawbacks. For example they're usually not very ambiently stable, and they're fluorescence isn't as controlled as we'd hope
And this is what I work on, trying to figure out how we can make these magic-sized nanocrystals compete with other state of the art semiconductor nanocrystals
@inaquantumdot @NorrisOMEL Yes, that's something Sergio from our group studies. His work on magic-sized cluster growth can be seen here: https://t.co/q1frRa0c3K You can see some of his other work on nanoplatelets here: https://t.co/3FdTXnIh85 In collaboration with @argwood @GalliGroup @UChiChemistry
Along with all the research, I think the teaching and mentoring aspect of my job is the most rewarding. As a postdoc at ETH, I've been able to serve as a lecturer, teaching a portion of the class "experimental methods for engineers" covering solar cells https://t.co/wfoOUoctcs
Teaching a lab course during the pandemic was difficult, and I couldn't have done it without my TA Julia @juja60 We had to video tape ourselves making the solar cells, and test them over zoom with the students https://t.co/orpHhM1twS
Something I didn't know before coming to ETH is that every bachelors and masters student has to write a thesis on a research project. This semester I'm supervising a bachelors student, and it's been a lot of fun working with her. Here are some nanocrystals she made today. https://t.co/PEEWUlIxMZ
I've also really enjoyed engaging with our local communities to expand access to science. During my time in @ChemColumbia, @MTekleSmith and I were really involved in these efforts
These events were always a lot of fun. Here we can see @KaiaParenti showing students a fun demo with an incandescent lightbulb. https://t.co/ee7dOq5XjG
Outside of the experiments, just getting to talk to these kids was always really interesting https://t.co/9XWBXf2UQQ
Being in a country where I don't speak the language, in the middle of a pandemic, community outreach opportunities have been a lot harder to come by
However there are still are sorts of programs that we can get involved with. In particular, last year I served as a mentor for @cientificolatin and their graduate school mentorship initiative
This is a great program that pairs students applying to grad school with mentors who are or have been in grad school. Their goal is to help underrepresented grad school applicants. I'd really encourage everyone to check it out: https://t.co/niWusV6hv9
I hope you've all enjoyed hearing a little bit about my scientific journey. For today I'll share some nice pictures of glowy stuff (credit to @NienhausFSU for the name) for #FluorescenceFriday Here are a couple of magic-sized clusters I made earlier this week https://t.co/cUAFjMv6Pu
[admin] Thank you Andrew for a wonderful week of science! 🥳 Do give @AndrewBPun a follow! Podcasts where Andrew takes a deeper dive into his research are - short - https://t.co/37JRhyhrh8 long - https://t.co/4UXDp2XSVk
Johanna Jochum
[admin] "Magnetism through the Eyes of Racing Neutrons" Please welcome @jkj_2309 for a week of awesome science and listen to the podcast to know what is coming your way - https://t.co/DIjHtPdsYW
Just a quick "Hello" 👋 and a short intro before I need to get some work done 😅 I am an instrument scientist @RESEDA_MLZ (I will tell you what exactly that means 😉) and my tweets this week will be about #neutron scattering, @RESEDA_MLZ , #magnetism, #superconductivity ...
and whatever else pops through my head. I might also post a bunch of pictures of mountains, because I come from the Austrian mountains and since we can't actually travel at the moment, I hope you will enjoy a virtual mountain short trip 😉 Have a good day, and see you at lunch 🙂
Hello again :) I am gonna start now with what I currently do ;) As I said I am an instrument scientist @RESEDA_MLZ, but what does that actually mean? @RESEDA_MLZ is one of many neutron scattering instruments at the @mlz_garching near Munich in Germany. https://t.co/qGAoY0gGeW
We are all getting our #neutrons from the FRM2, a research reactor that produces more than 1E14 neutrons per cm² per second through the nuclear fission of uranium. Here’s a picture of the FRM2 next to its predecessor the “Atom Egg”, now a landmark (Foto: W. Schürmann) https://t.co/UFZSx21LC2
These #neutrons are used by around 30 different instruments doing groundbreaking research in many, MANY different fields of science. This week I will focus on magnetic phenomena, but if you are interested in what else neutrons can be used for you should follow @mlz_garching...
...and check out our webpage. From battery research to biological systems, neutrons are a unique tool to explore different materials! (Three Instruments even have their own twitter account: @RESEDA_MLZ, @PandaMlz, @ErwiN_at_MLZ)
As an instrument scientist, I am responsible for one of the instruments @mlz_garching. In my case @RESEDA_MLZ. Firstly this means I need to make sure everything works ;) and since we are a user facility (scientists can write proposals and apply for beam time ...
... at any of our instruments) I am also responsible to help the visiting scientists with their experiments. And of course I get to do my own experiments as well (as you can see in this picture) https://t.co/RHfcbl3JDt
So, I hope you all had a good day, and are still up for some tweet sized bits of information about #neutron scattering and why neutrons are such a unique probe: https://t.co/zjRJYT7G6L
Neutrons are NOT charged, but they possess a magnetic spin. This allows them to penetrate deep into matter, and they are sensitive to magnetic phenomena within a sample. https://t.co/qzG4QoMnsN
On the downside the lack of electric charge makes them very hard to transport, since they can’t be accelerated with an electric field like charged particles...
For a long time neutrons were just flying through the air to pass from the source to instrument. Many neutrons were lost this way. Since the 70ies neutron guides have been in use...
They consist of nanostructured multilayers and transport neutrons of a certain wavelength range. Mostly they are made of Fe/Si or Ni/Ti. And this is what it looks like if you look through one: (Foto: @MCQST_cluster, Jan Greune) https://t.co/f7rMNgtrPX
One big advantage of neutrons is that in contrast to X-rays, the scattering cross-section of neutrons with the different elements does NOT scale with atomic number: https://t.co/c8NTN3iKam
Therefore, neutrons are much better at distinguishing elements that are next to each other in the periodic table. It is even possible to distinguish different isotopes (Image: https://t.co/8nOAqdyTMq)
@gns6w3 Indeed! It is crazy how well you can distinguish those with #neutrons and what possibilities this offers for soft matter research. Although for me personally as a hard condensed matter gal (and having had a pretty bad experience with a wrongly labelled target box)....
@gns6w3 ... the most amazing part is that you can distinguish Fe and Co so well :D
@Learn_Electron Thanks a lot for the compliment 🙂 Starting to make these sketches actually came out of necessity. I did a talk for the @DeutschesMuseum on #Superconductivity for which I needed to have the rights to all the images I was using, so I drew them myself 😄
@Learn_Electron @DeutschesMuseum A great inspiration for this was @Rob_Dimeo who does absolutely amazing sketches (also on neutron scattering🥰). Plus, I learned a lot from @rohdesign 's book "the Sketchnote Handbook"
Before starting with more #neutron scattering today, I wanna promote this nice Heraeus Seminar my colleagues are organizing! You will learn all there is to know about #magnetic SANS, plus there will be a lecture on MIEZE-SANS by yours truly @jkj_2309. Application is still open! https://t.co/HRzhnN5Tv4
Let’s dive a bit further into #neutron scattering. First a disclaimer: I am by far not an expert in all neutron scattering techniques, but I for sure can point you towards at least one for each of them if you want more information 😉
So, I will give you a brief overview of the different techniques, before diving into my field of expertise, the MIEZE technique, pretty fascinating a #neutron spin-echo technique (fun fact: MIEZE is basically German for kitty, which is why I got these nice ears in our hutch) https://t.co/jU4th4KahE
Let’s start with #neutron diffraction: Many of the (#nano) scientists here will be familiar with X-ray diffraction. Neutron diffraction is based on the same principles. A particle hits our sample, and we can observe a diffraction pattern. https://t.co/6d39vQ9MgA
For this we need to remember that the neutron can not just be described as a particle, but also as a wave. https://t.co/WhFLGWOWEr
From the diffraction pattern we can discern the crystal structure of our sample. #neutron vs. #Xray scattering? Due to their magnetic spin, neutrons can see underlying magnetic structures, so the diffraction pattern shows structural AND magnetic peaks. HOWEVER…
(since my background is nano science I am always a bit sad about the fact that the possibilities for #neutron scattering on nano structures is limited. There are of course neutron techniques for thin films, but we will get to that later)
I went to the FRM2 today, because a colleague told me he could show me a very special view of the triple axes spectrometer @PandaMlz. I am gonna share this with you: You can see here one of the monochromators of PANDA where #neutrons of a very specific energy are selected. https://t.co/DrmCUh8cO6
From this point, the neutrons fly towards the sample, which is where I am looking from. The 3 axes spectrometer gets its name from its 3 axes that can be moved completely independent from each other.
(In comparison, a #neutron diffraction instrument could also be called a 2 axes instrument). With a 3 axes spectrometer it is possible to measure excitations in a material with extreme accuracy .For example the energy dispersion of phonons, spin waves or any other excitation
The order in which I wanted to go through the different #neutron scattering instruments got a bit jumbled up yesterday when I got to see all the way inside @PandaMlz. But, I still think that was pretty cool, and I had to share it :)
And I just remembered that I did a crazy detailed sketch of @PandaMlz for the colleague who showed me this awesomeness, so, I am gonna share that now: https://t.co/0x3y0jtkf2
Next up is a spectroscopic method that is nicely complementary to 3 axis spectroscopy, #neutron Time-of-Flight (mostly referred to as ToF) spectroscopy. While for 3 axis spectroscopy the incoming neutron energy gets selected and scanned carefully to map out an excitation…
in ToF #neutrons of many different energies hit the sample. To gain information about the energy of the incoming and detected #neutron, their flight times are measured. ToF instruments usually have HUGE detector tanks to catch #neutrons in as large a solid angle as possible.
So, simplifying a lot, one could say that with a ToF instrument, you can cover excitations in a very large range of phase space, so it is amazing to get an overview of what is happening in your material…
With a 3 axes instrument on the other hand you can map out specific excitations in amazing detail. (Yes this is simplifying it a lot, but to really do these techniques justice would require a lecture of several hours for each of them, as you might guess from the sketch 😉)
[admin] "Magnetism through the Eyes of Racing Neutrons" Extended conversation with the amazing Johanna (@jkj_2309 ) is out now 🎙️👇🥳 https://t.co/oOkjAdRUVh
I have been working with a colleague on some old @RESEDA_MLZ data today. And I am gonna share a random thing with you now that I learned 😄 A #quantum critical point is a 2nd order #quantum phase transition.
Before diving into detail about @RESEDA_MLZ, which uses another #neutron spectroscopic method, I want to still mention some other cool #neutron scattering techniques. Going back to #neutron diffraction…
There is a #neutron diffraction setup specialized for structures that are between a few and a few thousand Angstroms “large” → the Small Angle Neutron Scattering Setup or SANS for short. SANS instruments are great at measuring the long range order of magnetic phenomena…
… as well as biological systems, polymers etc. Fun Fact: SANS machines are really long, and look a bit like Submarines, like for example the one @BNCHungary, which is even called “Yellow Submarine” (Image: https://t.co/cWDYzNAiM8) https://t.co/2JSb6FDvpD
Next up: #neutrons for #nanostructures ;) (Polarized) #neutron reflectometry, is the technique to study your thin film/superlattice/multilayer system. It provides information on structure and magnetism as a function of depth.
We actually measured a Co/CoO layer that was merely 3.5nm thick, as you can see in the sketch and beautiful #AFM image ;) (https://t.co/SSnnydH5Pm) https://t.co/nG4Nr4jdCg
I am gonna finish the round of #neutron scattering techniques with neutron imaging, which is a great way to look inside a thing, without destroying it. I attached a tweet with a super cool image comparing neutron and x-ray imaging on a camera...
and how awesomely they complement each other: https://t.co/2kMGCLEq4n And for my fellow nerds out there a special neutron imaging treat from @Phoenix_Nuclear https://t.co/HqWEzkzUGh
So, are you ready to learn more about spin-echo (SE) techniques and eventually @RESEDA_MLZ? Firstly, SE techniques use the fact that a spin in a magnetic field starts to precess like a spinning top… https://t.co/iyl3768J62
Now, if we have a very well defined magnetic field region (we know the length and field strength very well), and we know the speed/wavelength of our neutron (which we can ;) ) we can calculate how often the spin precesses. https://t.co/5hS18YtqNh
In a magnetic field that has the same length, and field strength but opposite sign, the spin would precess all the way back, like winding and then unwinding a watch.
So if we take two such magnetic fields, put a sample in between and a detector at the end, we can actually measure the dynamic properties of materials (yes I am simplifying here a bit as well 😉) https://t.co/TAq6DsZuGc
This technique is excellent to measure the dynamics of soft matter samples. However, it gets tricky if you want to measure anything magnetic. Because a magnetic field at the sample position would depolarize our neutron beam (mess with the “precession pattern”)
There is a SE technique that is optimized for anything magnetic, which is called MIEZE, and is the technique we used the most @RESEDA_MLZ. As you can see in the figure, RESEDA has two “arms”, so we can do spin-echo AND MIEZE. (Foto: Jan Greune @MCQST_cluster) https://t.co/NgosbiBCDw
More about MIEZE and RESEDA after lunch 😉 Stay tuned!
@gns6w3 Thank you! 🙂 For me the trickiest thing is always to know which explanation to go with, since there are so many ways of explaining SE... Classical, Semi-classical, Quantum Mechanical... Their suitability completely depends on the audience 😅
@gns6w3 Unfortunately, for MIEZE the classical explanation doesn't quite work anymore, and I am still trying to find the most intuitive way to explain it... I guess my audience here will serve as somewhat of a test audience 😅
@RESEDA_MLZ isn’t a classical SE setup. It is actually a #neutron RESONANT SEsetup. But what’s the difference? SE measures the (normalized intermediate) Scattering Function as a function of TIME rather than energy, which is what most other spectroscopic neutron instruments do…
The maximum time that can be reached depends on the length and strength of the magnetic field in the main coils. The larger they are the larger the time. Achieving a homogeneous magnetic field with larger and larger coils becomes exceedingly difficult...
So, Golub and Gähler came up with the idea to replace the big coils with resonant spin flippers, which are placed at the position where the edges of the big coil would be, the neutron resonant spin echo (NRSE) And you know what? The neutron doesn’t really notice the difference… https://t.co/jvf66aGhwD
The downside of this approach is, that the beam size usually has to be a bit smaller and some intensity is lost, which is why there are still more classical #neutron SE instruments, some of which are now using #superconducting coils! (e.g.: J-NSE @mlz_garching, Foto: O. Holderer) https://t.co/QWTmMykXOp
Let’s go to another advantage of NRSE: Imagine the neutron precessing in the magnetic field. To actually have it precess nicely (so the beam doesn’t depolarize) you need a minimum field, otherwise all sorts of magnetic field, even the earth magnetic field will disturb the neutron
NRSE offers a solution for this: Since there is now more space, since spin flippers are more compact than big solenoids, you can add another coil in between the flippers which can help you access shorter spin-echo times.
Now, it will become a bit tricky, since to explain MIEZE I will need a dash of quantum mechanics, but I hope you will bear with me… Let’s quickly remember, that while we can describe a neutron as a particle, we can also describe it as a wave! https://t.co/FztpdxUK0z
So instead of imagining a beam of neutrons flying through @RESEDA_MLZ, we can imagine neutron wave packets (yes we are going a bit #quantum here now). Much like #Schrödinger’s cat can quantum mechanically alive and dead… https://t.co/uFv0L6VmZH
(I know simplifying and trying to make quantum mechanics more intuitive is dangerous I hope all hard core quantum physicists forgive me for this)
The neutron wave packet we are looking at now has up and down spin. The spin flipper however treats up and down differently. The up-spin “part” gets faster while the down-spin “part” gets slower with respect to each other.
This is compensated at the second spin flipper. The trick is now however, to OVERCOMPENSATE. So the two parts of the wave package still need some time to catch up to each other, and at the point in space where they do, we put our detector.
Between the 2nd flipper and the detector we have an analyzer and our sample. The 2 wave packet parts will not arrive at the sample at the same time. So if in the time between their arrival something changes in the sample, we will notice this by a loss of contrast at the detector.
Since this is all a bit difficult to understand (believe me it took me months and many, MANY discussions with my colleagues before I finally understood this), I tried to nicely sum this all up in a #sketchnote https://t.co/cMOX93dudw
Since this was a bit intense, I will stop for now 😉 But later (or tomorrow, let’s see 😄) I will show you what cool science we can do using the MIEZE technique @RESEDA_MLZ
Here some typical @RESEDA_MLZ data 🤣 https://t.co/hUMpUchKhi
We can actually measure some pretty cool things! There have been a bunch of measurements on magnetic skyrmions! They are a pretty crazy (topologically non-trivial) magnetic structure! That’s what they look like: (Image: https://t.co/IFIxn9Fxsq) https://t.co/e0Ye8nSlsd
A colleague always compares them to what a hedgehog would look like if you would comb it! Anyways, together with our neighbours @mlz_garching, SANS-1 we provided #neutron data on the phase transition from the paramagnetic to skyrmion phase in MnSi.
The data recorded @RESEDA_MLZ showed that the transition state between the phases is not static but fluctuates! If you are curious, read more here: https://t.co/M2oAg2fbvp
I am visiting my family this weekend, and I was planning to share some niche mountain pics from home. but the weather isn't great 😅 We still went for a nice walk 🙂 https://t.co/oaYeriIpi4
After having had the privilege (because yes, nowadays it’s a privilege) of having eaten out at a restaurant (yes, we had a reservation at 5 because there is an 8 o’clock curfew) I am gonna share some more cool @RESEDA_MLZ data (oh and here the amazing desert): https://t.co/5TkKYvTYIW
I guess you have all heard about iron, and that it is a ferromagnet. But have you ever wonder what actually happens at the ferromagnetic - to paramagnetic phase transition? We studied the transition in detail @RESEDA_MLZ and here’s what we found:
Above the phase transition we found spin fluctuations that are slowing down as the phase transition is approached. The signal @RESEDA_MLZ looks like that: (btw this is from https://t.co/7fJGJauxd8) https://t.co/b8JijeH0K3
Below the phase transition we can see spin waves/magnons,which give those cool wiggles you can see here (which personally I find pretty cool :D) (from https://t.co/7fJGJauxd8) https://t.co/KyoCcIk0oF
And another cool thing: looking above the transition, we found that behaviour of the linewidth of the fluctuations as a function of q isn’t strictly quadratic! Which means that we can see some dipolar interactions!! (btw all of this was part of the PhD thesis of @stfnSaeubert)
Another grey day, however that didn't stop us from going for a short walk. We went to this nice small chapel, which was built in 1613, after Anna Planggin promised to build it, if the plague would not cross the village river… I guess it didn’t. https://t.co/YcMv1k7W4p
And since I couldn’t share nice sunny mountain pics from this weekend, here some I have taken over the last year. I know I enjoy them even more now that it isn’t really possible to travel. https://t.co/rCybpmwEd6
Since this is my last day curating I thought I’d still tell you a bit more about myself :D I studied physics @ETH. Yes, just physics, no specialty 😅 I actually took classes from quantum optics over superconductivity to astrophysics. And here’s a picture from my graduation: https://t.co/gEzBrTSFbz
After graduation I started a PhD in the material science department, which I quit after a year 😅 I learned that there is quite a big difference in how material scientists and physicists work, and I was too much of a physicist 😅 I still learned a lot during that year,
and I never regretted starting over. I eventually did my PhD @KU_Leuven. I studied magnetism, superconductivity and multiferroicity in nanostructures. It wasn’t always easy, but I met amazing people during my PhD and if you have those in your life, you can manage anything 🙂 https://t.co/s8nepviL8m
While I was finishing up my PhD I started working @RESEDA_MLZ. I actually started 3 years ago today :D In addition to everything I learned about neutron scattering and bulk materials (can you imagine that bulk people actually keep their samples for decades?)...
I also go the possibility to practice my #scicomm, Most recently, during my talk @DeutschesMuseum, where I talked about superconductivity 🙂 Here’s the link, for anyone who understands a bit of German 😉 https://t.co/yNJc8QgDJ1
So, I guess that was it, if you have any questions, as away! You can of course also always find me @jkj_2309 Take care everyone!
[admin] Huge thank you to Johanna for a wonderful week of science! Do give @jkj_2309 a follow! 🥳 Podcasts where Johanna speaks candidly about her science are here - Short - https://t.co/DIjHtPdsYW Long - https://t.co/oOkjAdRUVh https://t.co/z2AbztbLWa
Andrew Care
[admin] "A Secret Key to Unlock the Protein Nanocages" Please welcome @Dr_Andrew_care and listen to the podcast 👇🎙️ to know what is coming your way https://t.co/qKMOfdIrMi
G’day from downunder! I'm @Dr_Andrew_Care from the University of Technology Sydney (@UTSEngage) in Australia 🇦🇺 I'm excited to takeover @RealSci_Nano's twitter account! This week, I'll show you the crazy miniaturized world of protein nanocages! ...& maybe pics of my dog Molly 🐶
But to start, here's me arriving at @UTSEngage It's a classic autumn morning in Sydney today, with lots of sun and a fresh chill in the air ☀️🍂 https://t.co/kYu4Q8aNBZ
Let’s get to know each other! My research combines synthetic biology (or #SynBio) & #nanoscience. This includes taking natural proteins that self-assemble into nanoparticle-like structures and bioengineering them for use in biomed & biotech. We'll go deeper into this tomorrow... https://t.co/ZoeceC4DaV
I’m originally from New Zealand (NZ), making me a ‘Kiwi’ 🇳🇿🥝 NZ is known for its All Blacks rugby team & “The Lord of the Rings” films. But NZ was also the first country to let women vote; & it was kiwis who first climbed Mt Everest (Hillary) and split the atom (Rutherford)!! https://t.co/NC11etdH2B
In NZ, I got BSc in Biological Sciences from the University of Waikato (@waikato). This University is located in the farming city of Hamilton, giving it has a strong agricultural & horticultural research sector. https://t.co/ulWf35P9oy
In keeping with the ‘sheep’ theme…🐑 After my BSc, I took an industry job in NZ’s capital city of Wellington. There, I manufactured animal vaccines for @Merck. At the time, this was the largest single site for the production of veterinary vaccines in the world! https://t.co/cCxTvjJjeh
@johnazariah Kia Ora John. Kia kaha (keep strong)!
After my industry stint, I was ready to learn again, returning to the University of Waikato for my Masters degree. Here I used molecular biology techniques to profile bacterial populations in the GI tracts of obese people (i.e. the human gut #microbiome ) https://t.co/v7gPcMybaa
Time to earn some $$$ again. After my MSc, I relocated to the University of Auckland (@AucklandUni) where I worked on an industry project with NZ's largest milk producer @Fonterra. We were looking at the effect different probiotics had on different GI tract conditions. https://t.co/2R7lA0UIuv
'Crossing the ditch' In 2011, it was time for a new challenge... a PhD😬 So, after spending my entire career in NZ, I left Auckland and flew over the Tasman Sea to pursue a PhD in "Chemistry & Biomolecular Sciences" @Macquarie_Uni in Sydney, Australia! 🇳🇿✈️🇦🇺 https://t.co/cxzLKr3myR
My PhD investigated the utility of solid-binding peptides (SBPs), which strongly bind to different solid materials. SBPs can direct the assembly/functionalisation of materials, and can even mediate material synthesis/construction - kewl! Our SBP review 👉https://t.co/08NNVbrp6B
Following my PhD, I was lucky enough to score a post-doctoral position in the ARC Centre of Excellence in Nanoscale BioPhotonics (@CNBPscience). During this time, we engineered SBPs to functionalize #nanoparticles and mediate targeted drug delivery 👇 https://t.co/JOXdDOp9z6
In 2018, I was awarded a Cancer Institute New South Wales (@cancerNSW) ECR Fellowship. This amazing opportunity started my independent research career and allowed me to begin exploring the use of protein nanocages in #cancer #nanomedicine 🙌 https://t.co/36POR6ILey
And finally, in 2021, I received a Chancellor's Research Fellowship, giving our research team a new and exciting home @UTSengage. We think UTS is cutting-edge! After all, Wolverine is UTS alumni ... right @RealHughJackman ??? https://t.co/aUtkMdy4FJ
Alright, I'll see y'all tomorrow, where I promise it will be less me, and more protein cages https://t.co/hRqAzS5oul
PROTEIN CAGES! Nature is a professional LEGO master and it has chosen #proteins as its building blocks🧱 Example of nature’s #LEGO skills? PROTEIN CAGES: highly-ordered 3D structures that self-assemble from simple protein building blocks (subunits) @LEGO_Group @LEGOMastersAU https://t.co/j1yPN2aLkn
PROTEIN CAGES are everywhere and have important jobs to do! This is because PROTEIN CAGES have hollow internal cavities that serve as: reaction chambers for enzymes; storage containers for inorganic materials; and protective carriers for genetic material.... and more
There's sooooooo many PROTEIN CAGES!🤩 Protein cages can be categorized into: (1) Non-viral cages e.g., ferritins, vaults, lumazine synthase & encapsulins (2) Empty viral capsids (or virus-like particles) e.g., cowpea chlorotic mottle virus (CCMV), & Bacteriophages MS2 & P22. 👇 https://t.co/rCyocAMY2U
Great! Nature has provided us with a diverse toolbox of Protein Cages. Excitingly, Protein Cages can be modified by both genetic & chemical strategies. Also, they have 3 key engineerable components: (1) internal cavity; (2) external surface; (3) interfaces between the subunits. https://t.co/J0LQTCeENj
So what exactly are people re-engineering protein cages to do, you ask? https://t.co/YmERQlLWtI
The answer is, lot's ! Here's some random examples... VACCINES: The @HowarthSci lab established a protein nanocage platform to display both trimeric and tetrameric influenza antigens, enabling induction of potent neutralizing antibody responses. https://t.co/BWjtQ8Keyx
SYNTHETIC ORGANELLES: In this cool report, large protein cages were re-engineered to package #hydrogen-producing enzymes and integrated into a microbe. Following this action, the microbes displayed boosted #renewable hydrogen-production. https://t.co/ZMk0eJCQoI
TARGETED DRUG DELIVERY: Here, ferritin protein nanocages were loaded with therapeutic drugs and modified to enhance their targeted delivery to hypoxic tumor tissues. https://t.co/GhUAXQhCdC
You can read more about PROTEIN CAGES, including how they're engineered, and their widespread application in our review article👇 https://t.co/kNs4uDirld
Specifically interested in how PROTEIN CAGES can be developed into #therapeutic tools for #Cancer #nanomedicine? Maybe check out another one of our review articles 👇 https://t.co/QQ1N908AdN
Yay! Now that you have a sense of all the amazing and wonderful opportunities PROTEIN CAGES offer, I'll soon talk about some of our latest #research... https://t.co/IDVEhDd5Pf
@inaquantumdot @LEGO_Group @LEGOMastersAU Hi Ananya! Many protein cages have open pores that allow molecules to move in and/or out of their inner cavities. These pores can be 'static' with fixed diameters (usually under 1nm), or 'active/gated' with diameters that enlarge/shrink (open/close) in response to stimuli e.g. pH https://t.co/kIVdX8X6a9
[admin] "A Secret Key to Unlock the Protein Nanocages" Long conversation with @Dr_Andrew_Care it out now 👇🥳🎙️ https://t.co/MOThPfvieP
Hi everyone, here's some of our PROTEIN CAGE research. Here, we show how to re-program #encapsulin protein nanocages into photosensitizing nanoreactors for photodynamic therapy! I'll share the highlights below... https://t.co/se1aoDwyC6
Encapsulins are unique protein cages that self-assemble around #proteins tagged with an encapsulation signal peptide (ESig). We adapted this system to load the photosensitizing protein mini-SOG into the nanocages. Mini-SOG produces reactive oxygen species (ROS) under a blue-light
Excitingly, we found that these mini-SOG loaded encapsulins were capable of generating significant amounts of ROS when we fired a blue laser beam at them. ...We had made a light-activatable encapsulin nanoreactor that generates ROS "on-demand" https://t.co/XTI5nPAoH5
As a proof-of-concept, we explored the application of this nanoreactor in photodynamic therapy (PDT). In PDT, photosensitizing agents are activated by light to convert the oxygen inside tumor cells into lethal ROS, killing the cell.
We visualised the delivery of the encapsulin nanoreactor into tumour cells. Once inside, the nanoreactor was excited by blue-light and generated ROS, which induced intracellular oxidative stress and lowered tumor cell viability! This suggests our nanoreactor has potential in PDT! https://t.co/JdwXpjhr9X
Overall, our study showed that encapsulin protein cages can be readily bioengineered and are heaps of fun to play around with! We hope our work will encourage everyone to exploit the unique properties of these protein nanocages to create cool innovative #nanotechnologies https://t.co/P5sJuofJFf
Besides playing around with PROTEIN CAGES in the #research #laboratory, another part of my job @UTSEngage is #teaching. There's so many talented students at our #University and they make teaching alot of fun! #AcademicTwitter https://t.co/PaUt2NFKJE
I run the #innovation #entrepreneurship & #commercialization class @UTS_Science #Students use design-thinking to create products that solve big problems, then #pitch it to investors - like #SharkTank or #dragonsden!🦈🐲 Here's the "AsbestoMask" which detects asbestos levels😷 https://t.co/LzwWy9M7Dm
I also lead this year's @SynBioChallenge Team @UTSEngage. This is an awesome #Australia-wide #Syntheticbiology competition that gets #highereducation students to design and conduct a #SynBio project. Here's our team pitching their project! (hint: there's some Protein Cages 🤣) https://t.co/syOGxVRoiu
Before I say farewell, I thought I'd share what a weekend looks like here in #Sydney, #NSW, #Australia. It's beautiful spot, with a modern skyline, great sport stadiums, a picturesque harbor, white sand beaches, plenty of parks & #hiking trails. #WorkLifeBalance https://t.co/yyMED2LMYJ
Also, as promised, here's my dog Molly! She's not that great with a pipette in the #Laboratory, but is a real pro with a ball in the park! #dogsoftwitter https://t.co/KD2zxqke8r
Please feel free to reach out to me @utsengage if you're interested in talking or playing around with #synbio, #nanomedicine, or protein cages. Always happy to chat & collaborate! Follow: @Dr_Andrew_Care
[admin] Thank you @Dr_Andrew_Care for a wonderful week of nanoscience. Do give him a follow. To know more about Andrew's science, give podcasts a listen 👇🎙️ Short - https://t.co/qKMOfdIrMi Long - https://t.co/MOThPfvieP https://t.co/7VaAsuaqcV
Loreta Muscarella
[admin] "Who Performs Better Under High Pressure-Humans or Perovskites?" Please welcome Loreta (@la_muscarella) for a week of wonderful science and listen to the podcast to know what is coming your way this week 🎙️👇🥳 https://t.co/GARHUizCvR
Hi everybody! My name is Loreta Muscarella, I am a PhD student at @_amolf in the beautiful #Amsterdam and I'll curate this account for a week! Today I will talk a bit about my experience as expat and as international student! Looking forward to interacting with you all! 😎
Before talking about the present (and the future), I want to take you a little bit into my past and show you where I come from (get ready, a long compilation of pictures of sun and beaches are about to arrive!) ☀️
I was born in #Palermo, Sicily, the largest southernmost island in Italy. This city has a long story and still the capital of the island. Palermo overlooks the sea, in the picture is the Gulf of Mondello, the most popular beach (it is only 10 minutes from the city center!) https://t.co/BciBClVLRl
After so many years I still find this amazing... and I want to share with you! Every year in #Palermo, during the period preceding the beginning of summer, the sun rises at Porta Felice (one of the ancient entrances to the city) creating this wonderful effect ☀️ https://t.co/IBiwxgJ57D
During its long history, Sicily has been conquered by Arabs and Normans and we still retain much of their architecture and customs. #Markets are another important feature of Palermo, as in many Arab cities. And #streetfood is definitely worth trying, you won't regret it! https://t.co/h0vG88RTsO
@Dhiman_Roy_ Yes, indeed! They built the surrounding to witness this effect! Fantastic also at Kerala, it is truly majestic and enchanting 😍
@ElAbdleb Indeed, the Palermo vs. Catania is a very hot topic for football lovers! :D I am glad to share my enthusiasm for my city to you, you will definitely enjoy the city! And soon... perovskite stories!
Palermo represents my childhood and my period as teenager, but then at 18 I moved to #Rome to start studying at @SapienzaRoma where I did my Bachelor and MSc in Chemistry and Physical Chemistry. I guess no need to introduce Rome but I owe you a picture (or two!) https://t.co/AT6Z8iiWuM
Curious fact about @SapienzaRoma students: #Minerva is the symbol of my university and we have a beautiful sculpture in the center of the campus. But careful, if you want to graduate you should not look her in the eyes! And after graduation... ritual photo with Minerva! https://t.co/oW5tiTurA2
It's during my MSc at @SapienzaRoma that I started to have my first contacts with The Netherlands (where I live today) thanks to the @EUErasmusPlus project which I will tell you about in the next few days! ✈️
I spent 6 months in #Amsterdam for my thesis. This was my first time in Amsterdam, nice memories but also very tough time (I will tell you why very soon!). After this experience, I came back to Rome and after the defense I moved to The Netherlands to start my #PhD at @_amolf https://t.co/T1y7mP5NJ1
It's Jan. 2018 when I started my PhD @_amolf in the group of @brunoehrler - if you do the math this is my last year as PhD, and the defense somewhere in the beginning of next year. #pressure is ON! And speaking of pressure... this is also what my perovskites feel almost everyday!
This is @_amolf, I will tell you more about the research, people and opportunity in the next few days. In addition, some beautiful pictures of #Amsterdam during sunny days (I will keep the cloudy and rainy days for another occasion!) https://t.co/v4wV5s2ei8
Btw, today is holiday here! It's #WhitMonday. I'll leave you for today with this last pic of me and the #HybridSolarCells group (Dec. 2019) led by @brunoehrler. Tomorrow: what we do in the group and at @_amolf. Thanks for all your kind messages, feel free to write me anytime! https://t.co/j5sW2V4LiO
@jose__op @_amolf Thanks Jose! 🤗
Good morning everybody from a sunny Amsterdam! ☀️
As promised, today I am going to talk about @_amolf and in particular the #hybridsolarcells group where I am currently working. But before to start, I am curious to know what is your field of research, let's know each other a bit more! 👩🔬
What is @_amolf ? It's a research institute for Atomic and Molecular Physics based in Amsterdam, The Netherlads. We have 4 main branches: #DesignedMatter, #Nanophotovoltaics, #Nanophotonics and #LivingMatter. Each of these big departments is divided in smaller research groups
Examples of #designermatter are metamaterials that have mechanical or optical properties that do not occur in nature, self organized materials and active bio-inspired materials, which can mimic and outperform the functions of biological systems (source: https://t.co/lyDzXdexJN)
The researchers in the #Nanophotonics department use nanostractures to control the flow and confinement of light and investigate the material excitations that light interacts with: phonons, electrons, spins and excitons. (https://t.co/shHaVS9I4g)s
Researchers in the #livingmatter department focus on active cytoskeletal materials and biochemical regulation networks and the interplay between them combining experiments and modelling. (https://t.co/4dK0Bu67kA)
Researcher in the #nanophotovoltaics department focus on novel nano-structuring strategies to enhance light-matter interaction using photovoltaic semiconductor materials and hybrid bio-molecular structures for light collection and charge separation (https://t.co/WoaGhesqXE)
The #nanophotovoltaics department is divided in turn into: #3dphotovoltaics, #hybridsolarcells, #nanoscalesolarcells, #photonicsmaterials forming together the LMPV (Light Management in New Photovoltaic Materials). You should really have a look here: https://t.co/nVU5mggvR2
The #3Dphotovoltaics group (@3dPV_group) is led by dr. Esther Alarcón Lladó. Among the fantastic things they do (visit their Twitter page or AMOLF website to know more), they work on the growth of high-quality III-V semiconductor nanostructures using nanoelectrochemistry
The #photonicmaterials group (@PolmanGroup) led by Prof. Albert Polman focus on cathodoluminescence, optical metasurface performing mathematical operations, resonant metagratings for broad-angle colored photovoltaics and much more to discover in their Twitter or AMOLF page!
The #nanoscalesolarcells group led by Prof. Erik Garnett focuses, among many things, on broadband highly directive 3D nanophotonic, hot-electron photophysics and photochemistry with plasmonic nanostructures, understanding losses in solar cells. Have a look at their AMOLF page!
Last but not least, the group where I am doing the PhD, the #hybridsolarcells group led by @brunoehrler (visit his twitter account or the AMOLF page to know more!). We work on many topics (I will go in more detail in the next tweets): perovskites, singlet fission, quantum dots
[admin] ✨We take nominations now ✨ Know a materials/nano scientist who you want to see on this account? Tell us here - https://t.co/cOLqsDsENm https://t.co/8Eh3bGw6o5
That's all for today! Tomorrow I am going to talk a bit more in details ab about what I am doing at @_amolf. Be prepared for some stories of perovskites under pressure 🤯 Do they perform better than humans under pressure? Bets are open!
And if you would like to stay in contact, follow me at my personal Twitter account @la_muscarella 🐣
Good morning everybody! ☀️ Today it's time to discuss a bit about perovskites and how they behave under pressure 🗜️🤯
What is #perovskite? It's a class of compounds which have the same type of crystal structure as CaTiO3, known as the perovskite structure. Although the mineral was discovered in the Ural Mountains in 1839, its use in the field of PV, LEDs, scintillators (...) is quite recent
In particular, the type of perovskite used in these fields is the metal-halide perovskite with formula ABX3 where B is a divalent cation (mainly Pb2+ or Sn2+), X is the halide (I-, Br- or Cl-), and A+ is a monovalent cation that can be either organic or inorganic https://t.co/g69taq5ZHy
The structure I showed before is related to the 3D perovskite but there are also 2D ones used for the same applications. This class is even younger! In simple words, the idea here is that an A+ cation with a long chain (or an aromatic ring) is used as spacer inducing confinement https://t.co/RWqIAcVcs4
Now perovskites are very popular and you can also find lead-free perovskite and double perovskites where the Pb2+ is replaced by two cations of different oxidation state (a B+ and a B3+ for example) https://t.co/xBJFJ9oUz6
@ElAbdleb https://t.co/BP5GiqbeLb
As this material is so popular, it is easy to get confused about what is a perovskite from a crystallographic point of view. We tend to call everything derived from the ABX3 structure "perovskite" but it is not always correct: https://t.co/9ZWwJXAzZg
But why are these #perovskites so popular? Their easy fabrication in solution is one of the reason. You just need to mix the precursors in the solvents with no special expensive treatment to obtain your precursor solution. The most common solvents are DMF, DMSO, NMP
What is really amazing of this fabrication is that by changing the ratio of the precursor materials you can also tune the bandgap of your perovskite! For example, if you start to replace part of iodide with a bromide precursors you will obtain higher energy bandgap! https://t.co/pCOUMvzGKa
For the people not in the field, you should know that we like to use A LOT abbreviations. MA is the methylammonium cation and MAPI stands for MAPbI3, the most common perovskite we use
Speaking of the easy fabrication and easy bandgap tunability, these are very interesting for application where you want to be able to tune the bandgap of the material for example LEDs or tandem solar cells. But not all that glitters is gold...
If you have a mixed-halide perovskite in thin films and you apply an external bias or you illuminate the material, you loose the bandgap due to a process called "phase segregation". Ions in the perovskite are very mobile, and when illuminated they form I- and Br-rich domains https://t.co/hhRq0Qyfci
This is the paper: Hoke et al., Chem. Sci., 2015, 6, 613-617
Two questions raise now (or maybe more, so please ask in the comments!) : how do we investigate this process? What is the origin of this process? https://t.co/Ovus5x1WQG
[admin] "Who Performs Better Under High Pressure - Humans or Perovskites?" Extended conversation with @la_muscarella is out now, give it a listen 👇🎙️🎧 https://t.co/c865Wr6g6f
One technique for probing the phase segregation could be a photoluminescence-based technique, very common in many labs but... all the charges funnel into the low-energy iodide-rich domain so we cannot really probe the PL of all the domains https://t.co/h01tA9HwN0
We decided to use a pump-probe technique based on absorption, transient absorption spectroscopy setup. Clearly you can probe the mixed-phase but also the bromide and iodide-rich phase if you repeat the experiment after illuminating the film. https://t.co/zKE0Vwpny5 https://t.co/Xxtv9RkcRz
Now that we know what technique to use, let's do a step back to understand what possibly is the origin and how we can validate some theory...
One hypothesis for explaining why after illumination the series of mixed-halide shows a PL at 1.7 eV (= composition of 20% Br- incorporation) was a phase transition from tetragonal to cubic when the %Br is > than 20%. #Inotherwords the cubic structure is unstable...
I worked together with @emhutter1 on this project, it was a great time and fun together! There were also some very frustrating days but we know... it is how science works! We combined a transient absorption setup with a pressure cell to induce external compression in our films https://t.co/hg7hKJnAF1
Challenging? We had to perfectly align 3 beams inside this pressure cell. It looks big but the windows are very small... 3 beams for excitation, probing and inducing the phase segregation via light-soaking. It took a while but I am proud to share the results of all these efforts! https://t.co/GPxPxqxkGT
But okay, you might wonder, why pressure? In the range of pressure we use (0 to 0.3 GPa) there is no phase transition from cubic to tetragonal. So, if phase segregation stops cannot be due to the phase transition to the tetragonal phase
In addition, bromide and iodide-based perovskites have different compressibility (different bulk modulus) and the Gibbs free energy contains a PDV term we could use to see if pressure has a significant impact on the thermodynamic stability of our material...
This is what you get with a 50%Br sample when you illuminate at 0 and 0.3 GPa. At 0 GPa, immediately there is the formation of iodide- and bromide-rich phase (high and low energy), but very different behavior under pressure! More here: https://t.co/uv06kTk44i https://t.co/RmjxOXZxBj
This is true also when 70% of bromide is incorporated in the composition. Seems to be a very general effect. Btw, this is what each datapoint in the 2D plot I showed look like. These are the ground state bleach of the mixed, iodide- and bromide-rich domain https://t.co/dyHxPvooIG
If we fit all these peaks, this is what we get: the peak energy as a function of real time and pressure. https://t.co/QXereFEVcp https://t.co/HTyLR9db9S
First result: the final composition after light-soaking is different as a function of pressure (unit cell volume). The higher the pressure, the closer to the original mixed composition. Terminal x-value determined by volume instead of phase transition! https://t.co/0hmoG2tJpd https://t.co/V253au4irA
Under pressure, phase segregation becomes slower. If we derive the relation between the migration rate and the activation energy for the halides using the diffusion coefficient formula, we see that pressure seems to increase the activation energy for these halides to migrate https://t.co/PzBHUzktmf
Before to leave you for today, I have to tell you what we think is going on with pressure and these mixed-halide perovskites 🤔
When we compress the mixed-halide perovskite we are changing the PDV term in the Gibbs free energy of mixing. This term is usually overlooked for other semiconductors as much more stiff than perovskites. We also change the enthalpic term (due to strain in the material)
The enthalpic term is positive at ambient pressure and quite high because there is a lattice mismatch between the iodide- and the bromide- lattice. Under P, the iodide lattice compresses more (smaller bulk moduli than the bromide one) and the lattice mismatch reduces
#inotherwords: enthalpy dominates at ambient pressure, entropy dominates at high pressure where the enthalpic term reduces. Read more here: https://t.co/uv06kTk44i https://t.co/ICE2hvLWNb
You might say "Yeah, nice but we cannot put solar cells/LEDs under pressure". True, but we can induce strain to simulate the effect of the external pressure! We reduced the unit cell volume by using Cs+ instead of MA+. Similar results! https://t.co/QXereFEVcp https://t.co/VhVlZAwOIo
These works are just two examples on how fundamental studies can be useful for further optimization of devices. If you are doing fundamental science, it doesn't mean that is not important for applications! Actually, I think the opposite 🔥
Perovskite solar cells or LEDs cannot be put under pressure in real life, but they behave extremely good when a stress is applied. Next step? Let's transform this external pressure into internal pressure to obtain the same result 🧐
It's time to sleep here, but tomorrow I will talk a bit about another interesting effect of pressure on perovskites and my experience during the #ErasmusPlus project. Good night 🌙
Goodmorning world! ☀️ Yesterday I promised a bit more of perovskites under pressure and here it is..
Another interesting property of these halide perovskites is the extremely slow hot-carrier cooling in comparison with other semiconductors
When you excite a semiconductor with energy higher than the bandgap of the material you have excess of energy. When carriers move to the band edge to be collected (e.g. in solar cells), this excess of energy is lost... and also almost 35% of the efficiency...
This schematic from T. Gong et al., J. of Photonics for Energy, 6(4), 042510 (2016) can be very useful to visualize the process https://t.co/jzncewbj98
The timescale of this hot-carrier cooling (HCC) is still quite fast: picoseconds. Carriers cool down through scattering and being able to manipulate the scattering of electrons with phonons can have an impact on the HCC especially for polar semiconductors as perovskites
We need a technique fast enough to capture the evolution of these hot-carriers. It is high-speed photography. We need to make a ton of picture of our electrons/holes to look at this fast process in detail https://t.co/txirZYR3xC
And once again, I combined this with hydrostatic pressure. Why? Perovskites are polar semiconductors and electronic properties are expected to be strongly coupled with the lattice vibrations. Pressure can have an effect on phonons and therefore on the cooling https://t.co/acO9fd2LeG
The perovskite I studied here is the MAPI - the simplest perovskite with the A+ cation organic
We follow the tail of the ground state bleach as a function of time and pressure. The broad tail represents the presence of hot-electrons (with high energy). As a function of pressure the decay of the tail becomes faster and so the cooling. More here: https://t.co/He6X1kj1kx https://t.co/IDtvfz75bj
You see here that this effect is present only at a certain excitation density. We chose these two because these represent excitation density below and above the Mott transition (where polarons overlap). Below this threshold, pressure has no effect
Our collaborator @JarvistFrost calculated the electron-phonon coupling for each phonon mode as a function of pressure. The mode mostly affected by pressure is the one around 1 Thz, the octahedral twist. https://t.co/si1DyjbNhm
We think that when above the Mott transition, polarons overlap and form hotspot where heat is difficult to dissipate. Pressure increases the electron-phonon coupling and therefore offers new pathways to dissipate the excess of energy https://t.co/k5yOtEYHIQ
This is a fundamental study, how can this be used in real life? HCC is important for many applications. For example, thermoelectric devices require slow HCC, lasers and single-photon sources a fast one. Tuning the HCC allows to optimize the material depending on the application!
At @_amolf we also have a very special system for Electron Backscatter Diffraction (#EBSD). Maybe some of you working in material science know already this technique. It is combined with the SEM and we can construct spatially-resolved maps with structural data. Credits: Ivar Pel https://t.co/g6WCihg5Dl
Why is this special? It is a direct-electron detector meaning that there is no phosphor screen to enhance the signal. By using this, we can work with very low current and exposure time. Perovskites are also very sensitive (really to everything!)
This is my first work as PhD. I looked at MAPI perovskite and EBSD maps show that "grains" we see in the SEM most of the time are not a real grain but made of many crystallographic grains. Watch out for misleading SEM! More here: https://t.co/6gq2FDDgCn https://t.co/jDv0wR2nhb
I promised to talk about my experience as student in the context of the #Erasmus project. I definitely recommend all the students to apply for this opportunity. It’s not all rainbows and unicorns but it's a great experience everyone should do once in a lifetime
I found out about this Erasmus opportunity thanks to my Bachelor's thesis advisor (Prof. Ilaria Fratoddi, La Sapienza). She was coordinator of the Erasmus office. Every year she was trying to convince students to apply to do an experience abroad, either for exams or thesis
I was skeptical, i didn't want to do exams abroad (the ones at my uni were quite tough but the level was very high) but i wanted to see how people were working in Europe. On the other hand, i was just a student and my finances were not that great to live abroad for too long
My parents were ready to help me (as they were already doing since I decided to live in Rome for my studies) but let's be honest... Some countries in Europe are definitely much more expensive than living in Italy
Positive sides of the Erasmus scholarship is 1) you have a lot of choices. That depends a bit on your university but usually you have quite a lot of options. There are two version of this scholarship, in Europe or in the World
2) Part of your expenses are covered by the scholarship. Usually, depending on how "rich" is the destination country, you will receive more or less money. For example, Amsterdam is quite expensive and therefore I received more money than who went for example in Spain
3) you have to prove that you are actually doing what you were supposed to do. #inotherwords you cannot be paid by Erasmus to watch Netflix all day long but you have to show you attended classes, did exams or the internship
4) you meet a lot of people from different countries, with a different language, cousine culture and so on. You have no idea how much will enrich your soul! Diversity is what makes us better!
5) You go out from your "comfort zone". We are all good in doing what we always do, but there is no better way of learning new things by travelling, meeting people and experiencing a new environment
6) Professionally, you create a NETWORK. As scientists, we cannot work alone. We need collaboration to develop new concepts. Interdisciplinarity is the key of the future. Having a network of different scientists will bring a great benefit to your science and career!
@yanzhou918 Heeeello! It is when you illuminate the sample for a long period of time. In other words is just the exposure to light (can be sunlight or laser light)
Amsterdam is very cool if you come here with the Erasmus scholarship but it also has one major drawback to be aware of... housing! 🏠 Here, it is quite challenging to find an accomodation as there are many students and prices are not low. I had to change 2 times house in 6 months
This made my experience as international student quite tough and in some cases uncomfortable. So, be aware of looking for housing well in advance if you are planning to come to The Netherlands and don't feel alone... every other international student is probably having the same
I still remember when I said "The Netherlands? Never again"... and after 6 months I started my PhD again in Amsterdam 🤪
And this is my last group picture before to come back to Rome after the end of my Master's internship at @UvA_Amsterdam under the supervision of @WilliamsUvA. It was there that I started working with perovskites 💡 https://t.co/c4tBcR7MCU
@M__Soltani Thanks! Indeed, it is super interesting! Are you also working on a similar topic?
@moudouchem Thank you for sharing!
Good morning! ☀️Any plan for this friday? Lab work or work from home?
Today I want to talk with you about something that has dramatically changed in the last year and half. Something that is a very important part of our job as scientist: conferences. Did you have the chance to attend online conferences? What is your opinion?
@svenja_lohmann Oh, interesting! So there were not many online conferences in your field. May I ask what is your field of research?
@CedricPardanaud Was the conference on Zoom or on other platform? Recently I have seen https://t.co/q2iFnBiwOb used a lot for creating saloon to discuss and where to have poster session
In the PV/Perovskite field, we had the opportunity to attend many conference online. Most of them were organised by @nanoGe_Conf (thanks for the organization!) since the very beginning of the lockdown last March. I think the first one was in April. It looks like ages ago but...
I am going to share my experience with online conferences. Of course it cannot be a general truth because it depends a lot on how conferences are organised but this is my experience 🙃
I like a lot the fact that more people can attend. Not all the institutes and universities have enough money to send around their students and it is great to see that with lower prices more people can participate to online conferences. From all over the world!
Also, people that might not be able to travel for any kind of reason can still attend from their living room :)
I enjoyed most of the conferences although I really miss travelling. This was my last trip (February 2020) for a conference in #Sevilla. What a wonderful city! 😍 https://t.co/yrKJjZ1cVr
Conferences are a great opportunity to visit new places, know the culture of the country you visit, meet new people. I am extremely passionate of cousine and the food tour is a must every time I go for a conference. Yeah, I am also a kind of food blogger 🤣 https://t.co/Vt7V2DS0lS
A down side of online conferences is the short time for presentations. But on the other hand, it would be impossible to stay focused for 1 hour watching the screen of the PC. There's not really a solution for this 🤷 Sometimes is even difficult for 15 minutes!
To make a conference working, websites should function properly and being able to handle hundreds of participants! Once I was attending an online conference and it was crashing every 5 minutes. Not amazing 😐
Overall, my experience with online conference is positive! Some stuff are just not for me but i am glad that i could share my works with other people in a period where travelling was not possible.
What do you think of an hybrid format for the future when it will be possible to travel again? Do you think it can work? It would be great to travel again but also give the opportunity to attend conferences from home. What is your opinion?
Good morning people ☀️ I am shocked by the good weather and warm temperature in the following days! Maybe spring/summer is coming also here 😂 https://t.co/9vAcgawsVI
I want to know more about you all, what is your job? Do you work in academia or in a company? Doing a PhD/postdoc or are you a technician?
@RKarsthof Interesting! What kind of semiconductors?
@CalvaryCroll Oh nice! I studied these technique during my chemistry studies! What is your dream job?
@thiebes Fantastic! We should promote more this! Oftentimes people think that PhD is not compatible with having kids and being married. But it's fantastic when you have achievements in the private and scientific life ☺️ are you planning to stay in academia after your PhD?
@KaMeLPullin @MySci_PK Cool! I am always intrigued by electron microscopy. What kind of materials you work with?
@SaeedMAhsan1 Good luck with your PhD! What is the topic? What kind of materials do you study?
@RKarsthof Seems very cool! Do you also make these materials yourself? Is that challenging?
@ElAbdleb I am curious of many words of your reply! What is twistronics and moletronics?
@NithinGoona Interesting and i guess also quite challenging! What is the ultimate goal of this? Do you have an application in mind as well?
@ElAbdleb Very interesting! Do the 2D materials twist spontaneously by a twist angle or is it something doable only fabricating this on purpose?
Goodmorning everyone! I will stay with you this week as well! 😄
Thanks for all the replies to my tweets so far! It was great to know you better and know what you are doing in science. 😍
Following the topic of expat and international students. How many of you are doing a PhD/Postdoc/Other job abroad? How many in your home country?
@M_LaddParada Any plan to go back home?
@Felgraf_Physics Any plan to go back home?
@Felgraf_Physics I am curious, is there a big difference in terms of environment with your country? Something that you definitely prefer in comparison
@carlosromvil Are you continuing in academia?
@amy_mlinar Interesting? Do you like more the environment as compared to America?
@ElAbdleb Then I have a lot of questions for you :P I am curious on how you twist the layer? Is it something post fabrication or do you fabricate it already twisted?
@carlosromvil Fantastic! Good luck with your new job! What is your research field?
@HosseinMovla Cool! I wish you the best of luck!
Goodmorning everybody ☀️ Here is nice and warm, it reminds me my time in Sicily (difference is that usually in Sicily it lasts 4 months in a row instead of a couple of days but let's not complain!)
Something that I discussed in my podcast is the pressure (pressure is everywhere) of publishing. Do you also have the same in your field? How do you deal with it? I know some people who left academia due to this environment, but I would like to hear your thoughts and experience!
Changing the system is something not really possible from one day to another, but how we can change to deal with this type of environment? Tips and Tricks? @AcademicChatter
@srk_rodriguez But what if you work hard but it is still not possible to publish? Not always research gives us the expected result (my question goes a bit beyond PhD, but also for postdoc & tenure), should we blame ourselves for this? 1/2
@srk_rodriguez Many times I heard stories of people that could not have a job because judged on the numbers of publications. Does this number really define us? I agree with you about the healthy pressure, but how we can protect ourselves against the harmful pressure?
@evhauff @FraunhoferFEP @tudresden_de @VUamsterdam @VU_Science Congratulations Elizabeth! Have a good start in Dresden! :)
Pablo Ares
[admin] "Nano Fun with AFM (Atomic Force Microscopy)" Please welcome @pablerasares 🥳 Listen to the podcast to know what is coming your way in the next days 🎙️👇 https://t.co/9tm3rtpC9j
RT @realscientists: [Admin] A big science-y welcome to this week's curator, mathematician and @RealSci_Nano pro, Dr Lucia Rotheray (@LRothe…
RT @pablerasares: Next week I'll be curating the @RealSci_Nano twitter. I'll be talking about using atomic force microscopy to have fun wit…
Hi everyone! This week I'll be tweeting about my experience as a scientist. But since my trajectory is not the standard, I'll start by talking about how I got to where I am today. https://t.co/fUdrfSqM1Z
In the spring of 2003 I was about to graduate in Condensed Matter Physics at the Complutense University of Madrid @Fisicas_UCM. https://t.co/JWn6KE8Pvb
I was not sure what I wanted to do in the future. I saw then an advert of Nanotec Electronica (#Nanotec), looking for a recent graduate to join its staff. I applied and after a couple of interviews I got the position 🥳🥳
#Nanotec was a company devoted to the design, development and commercialization of scanning probe microscopes #SPM, mainly atomic force microscopes #AFM, so working for #Nanotec as an application scientist allowed me to have direct interaction with both industry and research https://t.co/r8A2krIggP
#Nanotec was a small company, spin off from the Autonomous University of Madrid @UAM_Madrid. It combined very talented people with different backgrounds (physicists, software and electronic engineers, chemists, technicians...) https://t.co/aVAqcfrcGG
At this time, I learnt a lot about #AFM, developing the technique and collaborating with researchers worldwide on different projects, which was great as it allowed me to see many of the things that can be done with an #AFM. https://t.co/yggsJa3Kz2
Basically, an #AFM uses a very tiny tip to "see" surfaces with nanometric resolution (later this week I'll talk more about how an #AFM works). For example, it can be used to study 0D materials such as nanoparticles or viruses https://t.co/wtAUsIu21O
And one of the best things is that the tip can be used also to modify and manipulate the samples, as for example indenting a virus to study its mechanical properties https://t.co/pF5JjvC9DM
We can also study 1D materials, such as carbon nanotubes, DNA or viral fibers, to name a few https://t.co/drTWuH75H5
2D materials, like the nowadays ubiquitous wonder material #graphene https://t.co/u59zDasi1d
Or 3D nanostructures such as cells, lithography features or different patterns on thin films https://t.co/M9A3D64Jvd
But as I told you, one of the best (and funniest) things of an #AFM is its ability to modify/manipulate things. Here is another example, making nanometric drawings, in this case by local oxidation of a silicon substrate https://t.co/d1TGPbcSIS
As #Nanotec was a small company, I had to do many different things, such as designing new parts for the microscopes, testing new developments, writing manuals, technical support, trainings and installations, attending conferences, demos for potential customers... https://t.co/7hSqPOjiCB
One of the things we did was to check that all our microscopes were able to "see" atoms, making sure the stability and noise levels were optimum https://t.co/24ZHsTBbpF
I had the opportunity to travel to different contries and meet many people. When going to a conference, we always carried an #AFM to show live all its capabilities https://t.co/O5wmSCK9Ru
Sometimes even in outdoor conditions!! But it behaved very well! (so well that data taken in this conference were used in a publication 😅) https://t.co/7rrnP0Xzri
At another conference, a meeting of GEFES, the Condensed Matter Physics Division of the Spanish Royal Physical Society @GEFES_RSEF, @epcienfuegos and I drew in situ the word GEFES using local oxidation, which became GEFES unofficial logo for several years 😄 https://t.co/JEhAVkYmO9
@epcienfuegos @GEFES_RSEF Me too!
#Nanotec had systems all over the world, which also allowed me to visit different places, including some exotic countries such as Ethiopia https://t.co/5OcB78pyQY
Normally, on my business trips I hardly had time for sightseeing, but going to Ethiopia I was warned that I could not leave without visiting Lalibela, where there were several medieval churches carved out of rock. Really impressive!! https://t.co/OPqChF0bx8
#Nanotec was somehow known in the community thanks to its software WSxM @WSXM_official. It was free and allowed many different options, but more importantly, it allowed opening files almost from any #AFM manufacturer and using all its image processing capabilities https://t.co/rVBqMcT2jp
I worked hand in hand with the software department to develop and test new options. For example, we developed a smart Flatten filter (very common in #AFM image processing) to reduce the low-frequency noise in a semi-automated way https://t.co/7sjFxmxhWC https://t.co/VdeXw9Hp1h
@WSXM_official is still being updated and adding new options, although at a slower pace than when there was #Nanotec. It's a really awesome software for #SPM, you can download it here 👉🏽 https://t.co/cv4gfyKM48
Sadly, in 2014 #Nanotec closed due to the global crisis, which in particular in Spain, where it had its main market, hit research hard, with significant cuts in its budgets. https://t.co/AZ2P8odh2N
At that time I had been collaborating for some time with researchers at the Universidad Autónoma de Madrid @UAM_Madrid (UAM) and when #Nanotec closed down, it came naturally to devote myself full time to research.
So I joined the Department of Condensed Matter Physics @fmcatuam of the UAM to get my PhD. During this time I also taught physics undergraduate classes, for which my experience of trainings and demos at #Nanotec was very important. https://t.co/guWUa5aiyg
In 2017 I obtained my PhD in Condensed Matter Physics and Nanotechnology. It was relatively fast, thanks mainly to the experience I had accumulated in my years at #Nanotec. Later this week I will talk about some of the research during my PhD. https://t.co/ZmAcI3PMvL
After obtaining my PhD, the opportunity arose for me to do a postdoc in the Graphene group at the University of Manchester @UoMPhysics. There, Dr. Laura Fumagalli @lfumagalli28, with whom I had collaborated during my time at #Nanotec, worked hard to get me to go there 😃 https://t.co/HLVfYt9o4A
I joined @UoMPhysics as a Research Associate to work mainly with @lfumagalli28 and Prof. Kostya Novoselov. Once there I got a Marie Sklodowska Curie @MSCActions, so in total I spent about three years in Manchester. Later this week I'll also talk about my research there https://t.co/ZR5sYphyDn
This time in Manchester was very important, as it allowed me to work in state-of-the-art facilities with scientists of the highest level @UoMGraphene. Personally it was hard, as my wife @cristalnurse stayed in Madrid, so we got to know Manchester Airport Terminal 3 very well 😅 https://t.co/83Urjmf4oT
When the Covid-19 pandemic broke out in March 2020 and the hardest lockdowns occurred, I had just travelled to Spain, so I spent that time with my family. When the university reopened in July, I went back to finish as much work as possible and in September I returned to Spain.
At the end of 2020 I rejoined the Department of Condensed Matter Physics at the UAM @fmcatuam as Assistant Professor and Junior Group Leader of its Condensed Matter Physics Center, IFIMAC @ifimacuam, where I am currently working. https://t.co/n6tJJA1HqS
Today I will try to show some of the basics of Scanning Probe Microscopy #SPM, and in particular, Atomic Force Microscopy #AFM. An easy way to understand how it works is to think on how the blind use their canes to follow the height changes in the floor. https://t.co/mBV25M3HJ0
Scanning Probe Microscopy #SPM is the general name of the family of microscopes that use a very sharp tip to detect an interaction with the surface. If this interaction decays very fast with tip-sample distance, then it will allow very small height changes to be detected.
The first #SPM was the Scanning Tunneling Microscope #STM. It takes advantage of the quantum tunneling effect. If a metal tip is at atomic distances(!!) of a metallic or semiconducting surface, a tunneling current that depends exponentially with the tip-sample distance can appear https://t.co/lXv0bEQHoo
The first #STM out of the IBM labs in Zurich @IBM was brought to the Autonoums University of Madrid @UAM_Madrid, being the origin of the #SPM tradition at UAM in particular, and in Spain in general. https://t.co/xIZNW44jQg
After the #STM, the #AFM (or SFM, from Scanning Force Microscopy) was developed. In this case, forces between tip and sample are detected. This allows to study any kind of sample, not only conductors or semiconductors, giving it a lot of versatility. https://t.co/ngQWGOByny
There are other #SPMs that can also detect light, and thanks to having the tip so close to the sample, they can overcome the diffraction limit. https://t.co/yEWZpRQQVd
Some of main components of an #AFM are the tip, the scanner, the control unit and the software. https://t.co/FL9ZrEya0R
Most of the #AFM tips come at the end of a cantilever beam integrated into a carrier chip. They are consumables and depending of the shape, size and material of the cantilever, we will have access to different ranges of forces and properties. https://t.co/Lp69dfpPD6
To detect the force between tip and sample, the deflection of the cantilever is detected. The most usual method for this is known as beam deflection: a laser is focused at the end of the cantilever and its reflection is monitored in a photodiode (gif from the University of Basel) https://t.co/P49VKl0WJR
Using a 4-cuadrant photodiode allows obtaining both the vertical deflection: Normal force, and the torsion of the cantilever: Lateral force, which is related to the friction. https://t.co/bv3uqXZEx3
Typical scanners in #AFMs are made of piezoelectric materials. These expand/contract when a voltage is applied to them, allowing atomic displacements in a very controlled way. They are used to scan the tip or sample and to move it up/down following the surface topography. https://t.co/HTiiDbKcYK
The control unit and the software drive the signals from/to the #AFM head, allowing the implementation of different measuring modes and custom experiments.
#AFMs spatial range typically is 0.1 nm-100 microns, and can detect forces between 10 pN and 10 microN, making #AFMs ideal tools for the nanoscale. https://t.co/0tyKe7vLFp
In #AFM, there are different interactions between the tip and the sample. This allows getting a lot of extra information apart from just topography. https://t.co/dI8upDS67J
This also enables multiple #AFM modes depending on the information you get. Sometimes the nomenclature can be overwhelming 🥴, but in the end all are #AFM 😅. But almost all of them are based on 3 basic modes: Contact, Dynamic (sometimes known as Tapping) and Force-distance based https://t.co/aKBoypTlOZ
In Contact mode the tip is touching the surface. This allows for example to obtain friction information. https://t.co/eEM7Z2TxuS
In Dynamic modes, the cantilever oscillates at or near its resonant frequency, either without touching the sample (non-contact) or with intermittent contact (depending on the oscillation settings). The Phase shift of the oscillation can map variations in surface properties. https://t.co/myviZ2jP2p
In Force-distance based modes, at each pixel of the image the tip is approaching/withdrawing from the surface (literally "jumping" from one point to another). This allows very precise control of the applied load and allows for adhesion and stiffness mapping. https://t.co/isNy1uHhye
#AFM also allows spectroscopic modes. The most basic spectroscopy is Force vs. distance plots, recording the force change with the tip-sample distance. From these plots a lot of information of the tip-sample interaction and properties of the surface can be gained. https://t.co/a6iy18VH2j
A clear utility of these curves is, for example, the study of protein folding, by pulling the bound proteins between an #AFM tip and a surface to understand their mechanical properties and interactions. https://t.co/07g8mRkVv5
Other #AFM modes allow for different characterization of samples. For example, in Conductive AFM #CAFM a conductive tip is used as a second mobile electrode to study transport properties on the nanoscale. https://t.co/eMgIOCuZWl
Or in Magnetic Force Microscopy #MFM, where a magnetic tip is used to probe nanoscale magnetic domains. As the magnetic interaction has a relative long range, by lifting the tip a few nm over the surface it can detect the magnetic interactions. https://t.co/R5AuyTAC6a
As I told you, there are plenty of different modes, so I will not go through all of them. Then, we also have the lithographic modes, where the tip is used to draw/modifiy/manipulate the samples. There are plenty of modes as well, I will mention now some of the most popular:
Among the most widespread we can find local oxidation, where the tip is used to carry out a local chemical reaction on the surface. https://t.co/jGcTh3wHMQ
Dip-pen nanolithography, where the tip is used as a "pen" to draw with a controlled release of molecules as "ink". https://t.co/6JPE6aATVR
Thermal scanning probe lithography t-SPL, where a special tip that can be heated is used for nano-patterning. https://t.co/Rgkvn0Ev6p
Nanomanipulation, to move nanoparticles, nanotubes, nanowires... In this case we can see the tip as a "finger" that can manipulate nano-objects at will. https://t.co/tOePviIuHq
@carlosromvil In principle yes. You can find more details on Phase imaging if you are interested here 👉🏽 https://t.co/XM6JylvEFP
@carlosromvil Here is an own example. This is a few-layer graphene flake on a diamond substrate. The phase contrast between both of them is clear, but for instance the triangular terrace in the diamond substrate presents no phase contrast. https://t.co/IWPAix9us5
All the capablities already mentioned together with the possibility of working under different environments make #AFM an extremely versatile tool. https://t.co/2cGMxwBVtw
Being able to work in liquids, its application for biological research is gaining more and more importance. Even more so with the latest generation of AFMs, which can work at high speed, allowing the visualisation of biological processes. See for example https://t.co/QvP0bF8XiK
It can also operate in ultra-high vacuum #UHV conditions at cryogenic temperatures. Under these conditions, a CO molecule can be attached to the tip end, allowing experiments with unprecedented resolution. https://t.co/FMACqYnA0S
Despite celebrating its 35th anniversary this year, #AFM is still an evolving technique in which a new breakthrough is made every few years. What will be the next...? https://t.co/kaonLH6fnK
@M__Soltani Most of the images and diagrams I have tweeted are my own, some may be adapted from my doctoral thesis or from some of my publications. In the few cases which are not mine, I have tried to put the reference in the image itself or in the tweet.
Today I will continue to talk about some of my work, focusing on 0D and 1D materials studied with #AFM. https://t.co/qEj9bq3R7M
I'll start with the development of Magnetic Force Microscopy #MFM in liquids, together with @JrcMiriam and @aasenjobar, allowing #MFM to study nano-bio-magnetic samples in their natural environment, hampered by how an #AFM works in liquid. Details here 👉🏼 https://t.co/giUz3oPlW1
First of all, just an idea on how the magnetic contrast appears in #MFM images. Depending on the orientation of the magnetic domains (out of plane, in plane or combinations), we will detect bright and dark contrast regions, as depicted here 👇🏼 https://t.co/k2NEu3FYsJ
The #MFM contrast is typically obtained in a Dynamic mode, in the Phase shift (or the Frequency shift) signal at a given lift distance. But a cantilever oscillating in liquid is subjected to much more drag than in air (or vacuum), worsening the signal. https://t.co/4FvVhM8fBX
We optimized the measuring mode and acquisition conditions to be able to detect similar #MFM constrasts in air and in liquid. We first used a calibration sample, such as a piece of a hard disk drive, visualizing its magnetic bits. https://t.co/dieffYyVlg
We observed that in liquids we could get the #MFM contrast oscillating the tip closer to the sample, allowing similar contrasts but noisier data, due to intrinsic limitations on the characteristics of the commercial #MFM probes, which are designed for measurements in air. https://t.co/Qqhj8HFDIz
Then we studied the magnetic contrast of 0D magnetic nanoparticles, such as those studied for hyperthermia cancer treatments, in buffer conditions somehow similar as to when injected into a human body. https://t.co/Y7M7eYJnNn
With such a demanding sample we were able to again obtain similar #MFM contrasts as in air, although not so good due to these intrinsic limitations on the probes. https://t.co/QODVuHY867
That is why, in collaboration with @deteresa5 group, we developed a method to fabricate magnetic tips on cantilevers designed for liquid measurements. Here all the details 👉🏼 https://t.co/pKYyrhU93i https://t.co/aagUUFbQ4m
We again tested these tips with a calibration hard disk drive, obtaining now results in liquid as good as in air. And moreover these tips are less invasive for the samples. In conclusion, the #MFM in liquids is now ready for the most demanding samples. https://t.co/UIGDJx00LV
[admin] "Nano Fun with AFM (Atomic Force Microscopy)" Extended conversation with the amazing @pablerasares ir out now 🎙️✨🎧 https://t.co/SygDKyF1z3
I will go on with another development, a setup for simultaneous high resolution #AFM and Total Internal Reflection Fluorescence #TIRF microscopy, really useful for studies at the single molecule level of viruses. This work was carried out in collaboration with Dr. P.J. de Pablo. https://t.co/tkkszncGiJ
In a #TIRF microscope the light is driven at the total internal reflection angle, and therefore only an evanescent wave reaches the sample, observing fluorescence mostly just from the nano-objects attached to the coverslip. https://t.co/8bRe1Sq0TU
The development of a simultaneous #AFM - #TIRF suitable for high resolution studies presents some challenges. Luckily, @alvrooe, who got his PhD with P.J. de Pablo and also worked with Dr. I. Schaap, had experience on it. https://t.co/93IQrIarp6
We designed a setup minimizing the mechanical loop of the system to reduce as much as possible instabilities, and used @WSXM_official to control our microscope, taking advantage of all its capabilities. We first tested it in ambient conditions, ensuring its high stability. https://t.co/RoJ9g7V2sx
We then tested it in buffer conditions, studying P22 viral particles, being able to visualize them and resolve different adsorption geometries and the capsomers forming the capsid. https://t.co/uXZvwfp8ZO
To test the combination of #AFM and #TIRF, we used commercial fluorescent polymer beads. We first simultaneously visualized them both with #AFM and #TIRF https://t.co/jVdvRVJpFW
And then we carried out a nanomanipulation experiment, removing on of the beads with the #AFM tip while we monitored it with the #TIRF https://t.co/ePeeehnDsA
This system is now operative at the @fmcatuam and @ifimacuam for a hot topic such as the study of viruses. A setup based on this one is also under construction at @UoMPhysics, as a multiplatform for simultaneous #AFM and optical studies.
@M__Soltani Thanks!
@ScienceByDRE @fmcatuam @ifimacuam @UoMPhysics @ourANU Sure, nice! We also had some experience with a MFP3D coupled to a TIRF, but we were not able to resolve viral capsids as well as with our system. But I'm sure this has improved as well now.
I'll move forward now to some examples of 1D nanostructures studied with #AFM. The first case is the high resolution visualization of double standed RNA #dsRNA in buffer conditions using different #AFM acquisition modes. Work in collaboration with @FMorenoHerrero. https://t.co/agtZdm7FHy
The details can be found in these two publications: https://t.co/lvZKIf4LfY https://t.co/8wO6vKx5Vf
#dsRNA plays an increasing list of roles: genetic material of a number of viruses, a key activator of the immune response against viral infections, and mediates the suppression of specific gene expression. All this raised interest to study its mechanical properties and structure.
#dsDNA had been extensively observed at high resolution with #AFM, but similar studies were lacking in #dsRNA. This was very likely because of the higher complexity of imaging the #dsRNA structure. https://t.co/D8CD2ew1RE
We first used #dsDNA as a molecular standard to adjust the conditions for high resolution imaging of nucleic acids in liquid. Then we imaged for the first time #dsRNA with a lateral resolution sufficient to resolve its helical periodicity with different #AFM acquisition modes. https://t.co/bbHf8aGZ8e
Finally, we simulated how the molecules would look like from their crystal structures with different tip radii R, finding that R<~2.5 nm allowed for both major and minor grooves visualization, while ~2.5 nm<R<~5.5 nm led to images where only a single periodicity was detected. https://t.co/LKeJF0oFeG
This work pointed out two critical aspects for high resolution of nucleic acids in liquid: 1- The interacting force, minimized fine-tuning each imaging mode parameter. 2- The sharpness of the tip, likely arising from a protrusion or a small feature at the apex of the tip.
I will now leave liquids aside and move on to another 1D system. In this case I will show you our results on the conductive properties of metal-organic fibres at the single-molecule level. This was the first of multiple fruitful collaborations with @fzamora0 https://t.co/cKWEoCcdl7
The details of the work can be found here 👉🏼 https://t.co/5PFvaksVpa
MMX metal-organic polymers are quasi-1D sequences of single halide atoms X bridging subunits with two metal ions MM connected by organic ligands. They are excellent conductors in bulk and as nanoribbons, but theoretical calculations predict even higher conductances than reported. https://t.co/CMtITMUoZ5
In this work we were able to produce individual chains of the above MMX polymer by a simple drop-casting procedure. By optical inspection we located the thicker fibres, and then with #AFM we could locate chains down to 1-2 nm height, compatible with just 1-2 MMX molecules. https://t.co/wBcioqwrzW
Next, we evaporated a sharp-edged electrode and observed it for molecules protruding. On these, with a metal-coated tip, we performed conductive #AFM, with the tip as a second mobile electrode. We were able to obtain resistance vs. lentgh plots down to the single-molecule level. https://t.co/DS8cs9bBV5
We found significative currents for a single-molecule experiment, even at distances beyond 250 nm, surpassing that of all other molecular wires reported so far!
However, the resistance was still much higher than predicted by calculations. Its exponential dependence with the distance pointed to Anderson localization caused by the interaction of electrons with structural defects.
To verify this, we did theoretical simulations at different levels, mimicking possible defects. We observed that iodine vacancies are the ones that reduce electron transmission the most, and that only 6-8% of vacancies would be responsible for the observed exponential behaviour. https://t.co/R9aEZog7Ht
This work puts into perspective the role of defects in electrical transport at the single-molecule level. And that, despite the influence of defects on electrical conductance, coordination polymers are one of the best choices for long-distance molecular wires.
@inaquantumdot These were done by our colleagues J.J Palacios and J. Soler. They basically first simulate the defects with Density Functional Theory (DFT), obtaining the electron transmission for each type.
@inaquantumdot Then, for the vacancy, they carried out quantum transport calculations using a single-orbital tight-binding model, with parameters fitted to reproduce the single-defect transmission.
To finish with 1D systems, I will show our work on the fabrication of nanoelectrodes by #AFM nanomanipulation and cold welding of gold nanowires, one of the funniest works I have done, also in collaboration with @fzamora. You can find the details here 👉🏼 https://t.co/bKv7XzNOXu
In our experiments studying electrical transport on the nanoscale, we found that conventional micro- and nanoelectrode fabrication presents some limitations: high temperatures while metal depositions, use of resins, chemical agents or static electrodes (non-reconfigurable)
We needed to overcome those limitations. We got to know about the work by Lu et al., Nat. Nanotechnol. 5, 218-224, 2010, where they used Transmission Electron Microscopy (TEM) to visualize the cold welding of gold nanowires #AuNWs, just by mechanical contact! https://t.co/89ol8m4Mtm
This is due to their high surface-to-volume ratio, similar to two water droplets merging into one when they touch. https://t.co/IWUNTowdPA
So we deposited #AuNWs on a substrate and using an #AFM tip successfully manipulated and cold welded them. https://t.co/weUuxG2PrG
We then fabricated devices following this procedure 👇🏼 https://t.co/oLD5s0dSlG
This way we obtained clean and reconfigurable nanoelectrodes, without the need of high temperatures, resins or chemical agents, that we could assembly into different configurations. https://t.co/fWbBlr0wP6
We first tested few-layer graphene, as it is a very well-studied material, with a single #AuNWs electrode + a metal #AFM tip as a second mobile electrode. We found electrical characteristics similar as using standard fabrication, but overcoming their abovementioned limitations. https://t.co/2VslGRGoqt
We wanted to check the quality of our #AuNWs electrodes, so we fabricated one close to 150 microns long, with almost 100 NWs. We found that its conductivity was almost that of bulk gold, with just a single grain boundary in each NW junction (BTW we contacted several 2D flakes 😅) https://t.co/hsxURwlDri
To test our nanoelectrodes we carried out multiple experiments in different configurations. Here my colleague M. Moreno-Moreno did an awesome job. For example, we fabricated another device on a few-laer graphene flake, but in this case in a more standard 4-terminal configuration. https://t.co/2DvJFjRuzO
We also wanted to push the limits of the technique, so we proceeded to make a device connecting a ~10 nm gold nanoparticle, something quite difficult without very expensive dedicated nanofabrication setups. https://t.co/tQ2mxyMLn8
Finally, we also explored its potential for molecular electronics. To this end, we approached two #AuNWs avoiding contact, and then coated them with 1,4-benzenedithiol molecules, measuring stable currents through the molecules for hours at room temperature, with great stability. https://t.co/7yfpWGrkHY
I think this is only the tip of the iceberg. #AFM is a very common tool, present in many labs and easily available, so this technique has the potential to provide a new and accessible platform for nanocircuitry fabrication, opening the door to a plethora of new experiments. https://t.co/800X3on7LZ
@muellerwHH Indeed!! The TEM movies from Lu et al. are totally amazing! They were really inspiring to develop our nanoelectrode fabrication technique.
Really impressive! Congrats! https://t.co/jfbRXRj4jQ
Today and tomorrow I will continue to tweet about some of my work, focusing now on AFM studies of 2D materials. https://t.co/xVM8ZujUez
I will start with a work on #graphene, where we tune its properties by applying ultrahigh pressures with a diamond 💎 #AFM tip. Details on this work can be found here 👉🏼 https://t.co/LXizWFTdBg https://t.co/UGZH2Wpdx6
An #AFM with a diamond tip can be seen as a nanotechnology version of a diamond anvil cell, the standard instrument for ultrahigh pressure experiments. https://t.co/ncDlIRMWcy
Since the Pressure is Force/Area, and the #AFM tips have nm-sized radii, with moderate forces we can apply ultrahigh pressures in a simple way. https://t.co/5mQSa6fB3K
When we were thinking about which material to try to squeeze hard with the tip of the #AFM, immediatly #graphene came to our minds. https://t.co/SO0SOYPppC
We used mechanically exfoliated high quality monolayer #graphene crystals. https://t.co/hECHKnv75w
We first imaged the flake in a Dynamic mode. Then we brought the tip into contact with a Pressure setpoint value and scanned under these conditions in a given area. After this, we brought the tip back to Dyanmic mode to visualize the modifications. https://t.co/M07dFyIRrJ
By controlling the Pressure setpoint we observed that we could control #graphene coupling with the underlying SiO2 substrate. https://t.co/UPO0uQcRXA
As the doping level is known to depend on this degree of coupling, we were expecting to control the doping level locally on these areas, which we confirmed by Raman spectrosocopy https://t.co/G9l9Hnzigm
And also by Kelvin Probe Force Microscopy, #KPFM, an advanced electrical #AFM mode that allows to measure surface potential differences. https://t.co/iqlIeusEPu
Therefore, with this ultrahigh pressure modifications, we were able to tune locally the electronic properties of #graphene. https://t.co/MHsAQJODQw
To understand the origin of this doping, we carried out some theoretical simulations, that pointed out that some of the carbon atoms of #graphene could be bonding to the substrate, even if very few, being responsible for the observed charge transfer. https://t.co/hl0Tp88LEV
We took some samples to the Elettra Synchrotron in Trieste, to a beamline allowing imaging spectromicroscopy and microspot spectroscopic modes. The spectra showed an extra component in the carbon peak, compatible with some carbon atoms of #graphene bonding to the substrate. https://t.co/UQrZxJMJL8
We studied the electrical resistance of ultrahigh pressure modifed areas using conductive #AFM. These doped areas presented lower resistance, therefore this appraoch could be used to improve metal contacts in #graphene devices, leading for example to less power comsuption. https://t.co/sgxbONUbfX
I will continue with ultrahigh pressure experiments on #graphene. Since we could improve the coupling to the substrate, we decided to apply it to better seal blisters consisting on #graphene over microcavities, a standard setup for nanomechanical devices and membrane applications https://t.co/mIl5kjRUGm
Some of the people involved in this work include @yolicomoelrio, @JrcMiriam, and the details are here: https://t.co/kxLwg6IBoN
In the group there was a lot of experience studying #graphene mechanical properties upon #AFM nanoindentations with these blisters, also at different pressures, having an #AFM in a variable pressure chamber from high vacuum to several bar. So we could inflate/deflate the blisters https://t.co/M94LhXk2Sm
Studying the height evolution with time, we saw the gas inside our blisters typically leaked in a few hours. https://t.co/400J9yshfZ
The leakage was faster in a given flake for blisters closer to the flake's edge. With a simple toy model (tha gas leaking through a cilindrical pipe), we could estimate an effective leakage radius, and this was independent of the distance to the edge for a given flake. https://t.co/RAT3iB5XcL
Since the leaks of the blisters can be a drawback for technological applications, we tried to improve them by sealing the blisters applying ultrahigh pressures with the shape of a nanometric wide square rim. https://t.co/kzoTJychqj
In this way, we effectively sealed the blisters, significantly increasing leakage times. Importantly, this demonstrated that most of the gas leakage takes place at the interface between #graphene and the substrate and not by diffusion through the microcavity walls. https://t.co/rOTWhdxn5u
We observed an improvement of the leakage times and a reduction of the effective leakage radius in all the cases, proving this methodology as a simple way for easy improvement of devices and membrane applications based on #graphene on SiO2 substrates. https://t.co/LuZEpcXFLw
Next I will tweet about a novel 2D material isolated for the first time in my PhD, #antimonene, a single layer of antimony atoms. We published several works that have attracted the interest of the scientific community, opening the path for the experimental research on this field. https://t.co/q13V0zegTS
Many people involved, including @Fernandastico, @alonsoxK93, @SDiazTendero, @fzamora0, @carlosgp92, @__mariavarela, @Gonzalo_Abellan, together with other #notinTweeter authors. Here the links for the two main publications: https://t.co/aU53SRdBGy https://t.co/h3r1tR4SmE
Back in 2015, there was a great interest (and there is still) in finding 2D materials with electronic gaps between 0.5 and 1.5 eV, suitable for some optoelectronic applications. Thin layers of Black Phosphorus (BP) were isolated, presenting gaps on this range. https://t.co/4CuanfW1c9
But BP is highly hygroscopic, this is, it absorbs water from ambient humidity, degrading and changing completely its properties, needing to work under control environments or to encapsulate it to take advantage of all its potential. https://t.co/ZPGKOt8grD
In the same column of the periodic table as phosphorus is antimony, which is also a layered material, although with stronger interactions between the layers. https://t.co/6G25p38Wcj
At that time, there were a lot of theoretical papers predicting very interesting properties for #antimonene and few-layer antimonene, but nobody had isolated it yet. https://t.co/AHVyfZBscg
We were able to isolate it, first using a micromechanical exfoliation approach and later using a liquid phase exfoliation procedure. https://t.co/nWIt6vHlzi
After exfoliation and deposition on a substrate, we inspect it with optical microscopy, finding large thick flakes. But when scanning with the #AFM around these flakes, we usually found smaller thinner ones, with terraces down to ~2 nm, compatible with 2-3 layers. https://t.co/YaYP9FRvjy
We used a battery of techniques to confirm the antimony nature of these flakes, including high resolution #AFM visualizing their atomic lattice. https://t.co/KyEfSn1ZET
We sometimes found terraces below 1 nm, compatible with single layers (the presence of trapped molecules between flakes and the substrate can induce to observe these heights when scanning single layers of 2D materials). How to check if these terraces where indeed single layers?
We used again #AFM, in this case to manipulate a terrace, folding it over the rest of the flake. By measuring the height of a sinlge fold we found ~0.4 nm, in good agreement with a single layer of #antimonene. https://t.co/bixEblMl2U
Finally, we tested their stability, imaging some flakes with #AFM. After 2 months in a box at ambient conditions, we imaged them again and they looked exactly the same. We immersed them in water, and they still looked the same (even seeing the atomic lattice in these conditions) https://t.co/7PwQe316jP
These experiments demonstrated the possibility of isolating #antimonene and proved its stability, opening the door to its use for different purposes. https://t.co/VK0oNXTpba
I'll finish today by delving a little deeper into #antimonene. We also did some studies on its optical properties and noncovalent functionalization. The details for these two works in these links: https://t.co/zlmhMS8j7T https://t.co/N9DsT8a7Br
We combined optical microscopy characterization at different wavelengths with #AFM heights to obtain few-layer #antimonene refraction index, following a similar prodecure used with #graphene and other 2D materials, based on a Fresnel law model. https://t.co/xIEAkqporY
In this way, we were able to obtain the refraction index in the visible region and also to study the optical contrast as a function of the thickness of the SiO2 substrate, finding the optimal ones to work with #antimonene. https://t.co/2GvlzZcDzK
We also explored chemical properties of #antimonene, carrying out the noncovalent functionalization of few-layer flakes. We functionalized the flakes by drop-casting a THF solution of a tailormade EDTA-PDI (EDTA=ethylenediaminetetraacetic acid) derivative on the flakes.
We characterized them using different techniques, including #AFM, which for example allowed us to quantify the increment in thickness from the molecules attached to the flakes. https://t.co/ZhiNpy7JCl
We carried out synchrotron measurements, showing that the functionalizing molecule acts as an electron acceptor, in good agreement with our theoterical calculations. https://t.co/uBRwYbCYwf
These experiments indicate that the noncovalent functionalization of #antimonene gives rise to a charge-transfer band gap of ~ 1 eV, being a promising route for tailoring its electronic properties.
Today I will continue to tweet about some of my AFM studies on 2D materials. Let's try to debunk the myth that sequels are never any good! 😅 https://t.co/XxbH3QV0Y0
I will start with our work using 2D materials to fabricate nanochannels to confine water with atomic-thickness precision and then study its dielectric properties once confined. https://t.co/RjxjYhQ7aP
Here I want to shout-out to @lfumagalli28: she led the project and is one of the world's experts in scanning dielectric microscopy. The details of the work here 👉🏼 https://t.co/1bCrAqrj0F
Taking advantage of the experience and facilities at @UoMPhysics @UoMGraphene, we fabricated nanochannel devices where the height of the channels is given by the thickness of layers of 2D materials, enabling to control it at the atomic level. https://t.co/zkbY6E2ve0
Here are some optical images from our devices, where the thicker channels are clearly visible, and even where we could see when water filled them. https://t.co/pw9AkzYrIm
But for the thinner channels it was not possible to detect optically if the water was in. To this end, we used #AFM to image the devices before and after water filling. https://t.co/N76hc3UGeD
When the channels are empty, the top cover sags into them, but when water is present, the water pushes it upwards and the sagging disappears. https://t.co/cbwR4dE2HC
Then, by using scanning dielectric microscopy, we were able to probe the out-of-plane dielectric properties of the water confined in the nanochannels. https://t.co/xUfS3lMLJZ
We found a strong contrast that reversed with decreasing thickness, indicating that the polarizability of confined water strongly depended on its thickness and reaches values less than that of hBN, with an already low dielectric constant of ~3.5 https://t.co/6YxqF83emV
By carefully determining the tip geometry and its radius, using finite-element analysis we could quantify the value of the out-of-plane dielectric constant of water for the different thicknesses. Recognition here to @reneif07 as well. https://t.co/KFJxaRhmFv
By doing so, we could plot the out-of-plane dielectric constant of water as a function of thickness down to less than 1 nm, finding an anomalously low value of ~2 when extremely confined!! https://t.co/KC7WiBcu8l
Our results revealed the presence of an interfacial "dead" layer two to three molecules thick, and are important for better understanding interactions in biological systems, in areas such as electrochemistry and energy storage, or to fine-tune future simulations of confined water
The gif above was incomplete 😅, here is the right one https://t.co/qrLA31g9KI
I will go on with our work on studying the piezoelectric properties of single layer #hBN using #AFM electrostatic measurements #EFM. People in this work also include @lfumagalli28, and the details can be found here: https://t.co/TPaPrA5z2J https://t.co/iFdqyH5zXs
The piezoelectric effect is an important property consisting in the internal generation of electrical charge resulting from an applied mechanical force. https://t.co/t4FcLhFNcH
For piezoelectricity to appear, it is needed a broken symmetry in the material structure. Centrosymetric crystals, such as graphene for instance, where all are carbon atoms, are not piezoelectric. https://t.co/0ro2lBXspi
When symmetry is broken, as in non-centrosymmetric crystals, piezoelectricity arises. This is the case of single layers of 2D materials such as #MoS2 or #hBN, for example. But when symmetry is recovered, as in bilayers (in general, even number of layers), piezoelectricity is lost https://t.co/XNS6ubYoNK
We used a variant of electrostatic force microscopy #EFM in such a way that we got an electric image, coming from the electric fields from the sample, and a simultaneous dielectric map, that we used as a control image to rule out artefacts and crosstalks. https://t.co/MZcvK5FNEa
We deposited single layers of #hBN on other 2D (starting with bottom #hBN), favouring bubbles and creases. We then obtained #EFM images of these areas, as bubbles and creases are features inducing high strain, observing high contrast within and especially around the bubbles. https://t.co/SPL0KDKo2C
The contrast inside the bubbles was also visible in the dielectric maps, and could also come from the substances trapped inside or be a topographical crosstalk. But around the bubbles the areas are perfectly clean and flat, so the contrast could be due to piezoelectricity.
We took images of bubbles with well-defined shapes and made theoretical simulations mimicking those shapes, finding a fairly good agreement, confirming the piezoelectric origin of the observed contrast. https://t.co/ikdwh6u96q
In the case of depositing single layer #hBN on bottom #graphene, we also observed contrast around bubbles. https://t.co/j8PTxIUdU1
A closer look at this areas indicated the presence of ultrathin creases, which we also mimicked theoretically, showing a good agreeement with the measurements. https://t.co/kM4tT998uR
We confirmed the piezoelectric origin carrying out a battery of control experiments where no piezoelectricity was expected, such as areas without strain, bilayer #hBN or graphene bubbles and ultrathin creases. None of them showed the contrast observed in single layer #hBN. https://t.co/ftGQ2VrTvN
Our work gave evidence of the generation of piezoelectric fields in highly strained single layer #hBN, important if monolayer #hBN is used to encapsulate other 2Ds, and we also showed how electrostatic #AFM (#EFM, #KPFM) can be used to detect piezoelectricity on the nanoscale.
I will continue with more experiments related to bubbles in 2D materials. In particular, the effects of van der Waals (vdW) interactions in the formation of wrinkles around bubbles. Again with @lfumagalli28 among other #notinTwitter authors. Details here 👉🏼https://t.co/z2Cb0WK5G8 https://t.co/eakCj6LjnQ
While studying the piezoelectricity in single layer #hBN, we noticed the occasional appearance of wrinkles around bubbles. For example, their formation was favoured by exposure of the samples to high humidity. https://t.co/pMTCXNRiqL
We prepared high-quality vdW heterostructures with atomically flat monocrystals of #hBN and #MoS2 presenting different thicknesses, promoting the formation of wrinkles around bubbles. We imaged them using #AFM and measured the wavelentgh of the undulations. https://t.co/IdjRmgNFmI
We started with incommensurate samples (atomic lattices between the botom and the top 2D materials were not aligned) and we observed radial wrinkles whose wavelength ℓ depended on the thickness of the membranes. https://t.co/akrq5d6Qfl
We developed a theoretical framework based on the "local wavelength law". The bending rigidity favors undulations with large ℓ, and the restoring forces small ℓ. At long ℓ, the mutual slippage between the layers is suppressed while at short ℓ, intralayer slippage is prominent https://t.co/qzJjMPitEB
We also produced commensurate samples (atomic lattices aligned between bottom and top 2Ds) of monolayer #hBN. A moiré pattern appeared and the behavior was different: the wrinkles exhibited a substantial deviation from radial orientation and became constrained to the moiré. https://t.co/eDqCch4kNB
Our #AFM measurements of the various features of the deformed membranes can be harnessed to provide a very convenient, indirect metrological probe for the dependence of the bending rigidity on the number of atomic layers and for the magnitude and steepness of the vdW potential. https://t.co/RXB5ZyFrsl
The last work I'll tweet about is our study of #hBN crystals stacked at small twist angle. We used #AFM to see ferroelectric-like domains arranged in triangular superlattices. People in this work include again @lfumagalli28 and @reneif07, details here 👉🏼 https://t.co/bWqnKv7nRF
One of the most promising avenues for controlling the properties of vdW heterostructures is to adjust the angle between the stacked 2D crystals. https://t.co/pMj44bO8bP
In this work, we produced #hBN crystals placed at an intentionally small twist angle, so they create a superlattice of charge-polarized macroscopic domains confined to the interface. https://t.co/UqXnKUVuEa
The #hBN unit cell has two non-identical sublattices, resulting in two cases of perfect alignment, parallel and antiparallel, giving rise to six highly symmetric stacking configurations for an hBN-hBN interface that differ in the position of the interfacial N and B atoms. https://t.co/EWJbPVX9YI
We used #AFM electrostatic modes #EFM and #KPFM to visualize the ferroelectric-like electrostatic supperlattices caused by the different stacking domains in vdW structures of several thicknesses. https://t.co/4xAtF4L6do
We detected no superlattice patterns in the topography images, but we detected clear triangular domains periodically arranged in many regions in the electrostatic images. https://t.co/V2noDOnqqG
Twisted heterostructures with monolayer steps on the surface of the bottom #hBN crystal showed clear triangular pattern only on one side of the terrace, suggesting that periodic domains are possible only for one orientation type, either parallel or antiparallel. https://t.co/eticI4TIZc
We calculated superlattice reconstructions at the twisted hBN interface, that when compared with the #EFM and #KPFM results strongly suggest that the observed superlattices represent the parallel alignment with alternating AB and BA domains. https://t.co/QSc6mgdgzd
This worked showed a simple and non-destructive #AFM technique able to visualize moiré-superlattice electrostatic potentials. The demonstrated charge-polarized superlattices provide a fascinating platform to study superlattice phenomena and engineer vdW heterostructures.
This weekend I am in my hometown visiting my parents, so I will not be tweeting new content.
This week at @RealSci_Nano has been a pleasure. I hope you enjoyed my tweets and, if you didn't know about atomic force microscopy #AFM, I hope I showed you the many possibilities it offers.
Finally, I'd like to use this platform to make an announcement: my colleague and friend Guillermo López-Polín and I are co-editing a special issue in «Materials» entitled "Use and Development of Scanning Probe Microscopy in Low-Dimensional Systems" https://t.co/pJprrrzJfi
The special issue has just been opened for submissions, so you are welcome to submit your manuscripts on the use and development of #SPM (#AFM, #STM...), both from experimental and theoretical points of view, for the study of low-dimensional systems. https://t.co/oNtqFgr5Kc
[admin] Big thank you to @pablerasares for a week full of atomic force microscopy. Do give him a follow! Podcasts featuring Pablo are 👇 Short - https://t.co/9tm3rt81hL Long - https://t.co/SygDKyF1z3 https://t.co/S9JeTlHSH5
William Brant
[admin] "Embracing Change - Materials for Greener Tomorrow" Please welcome @willrbrant1 🥳 Listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/iHSjfZlxzL
Good morning everyone, great to be here this week! My name is Dr William Brant and I am an Assisstant Professor in the @StructuralChem1 group which is part of the @chem_angstrom department at @UU_University. See below for a preview of what I will talk about this week. https://t.co/x6zP4G8iTv
I will kick this week off by talking about how I got to where I am today almost 16 000 km away from home. What really attracted me to the science that made me relocate this far and naturally some details about the science.
Of course, science is a big part of my life but it is not all there is to it. So later today I will give a sneak peek into a very nerdy hobby that I have :).
For now, it is Monday morning and that means group meetings! It is good to start the week with a refresher on what is to come when you have a fresh head. I will return in 2 hours! https://t.co/RnLuEyT3Es
Ok morning meetings done! I will kick off today by talking a little bit about how I ended up all the way in Sweden. I originally did my undergraduate studies within at @Sydney_Uni. I was actually originally studying a combined science, commerce degree at the time!
However, in my third year I rediscovered my love for crystals and discovered the joys of #crystallography in the solid state chemistry course. This led to a research project in @SydneyChemistry in 2009 on lithium conduction in defect perovskites that grew into my PhD project. https://t.co/kvxdQYj7hG
I will talk more on the science of my project later. For now how did I find my way to Sweden? Well, I was fortunate enough in my PhD to have to opportunity to travel abroad to conferences. Such as AsCA in Busan Korea (where I looked very different compared to today...) https://t.co/0dU1K9q8QD
Attending conferences is a great way to meet and network with others in the field. It was one conference in particular that really taught me that its not what you know but who you know. This was the International Meeting of Lithium-Ion Batteries on Jeju Island, Korea in 2012.
There I met a researcher from the @angstromABC who was working on building devices for studying battery materials using #neutrons. As I was working on this too I started a dialogue with him which turned into discussions of a collaboration.
Next thing you know, a year later I found myself in Sweden and then the @isisneutronmuon source to perform experiments connected to this collaboration. It was also my first experience of building batteries in a glovebox...it isn't easy. https://t.co/uLu5RTfzQG
However, the week I was in Sweden preparing I had the great fortune to meet @KristinaEdstrm2 and Dr Torbjörn Gustafsson, both of whom had a long history of studying battery materials with diffraction. Including the first in situ neutron experiment on a custom built battery.
While brief, this meeting led to Prof. Edström offering me a postdoc position in 2015 working in the @StructuralChem1 group and continuing my work on methods of studying batteries during operation using diffraction. I have been here ever since :).
So, what have I learned from this journey? - You never know where or when you might run into that career changing collaboration - Networking is key for finding opportunities in the first place - Sometimes relocating to a new country is needed to utilise these opportunities
I think one final thing I need to add is that, looking back I never would have predicted this path. Or that I would end up potentially permantly in Sweden. So keep an open mind about career paths and opportunities :) https://t.co/8QRD7iK8Uc
@M_LaddParada I wanted to mention also all the friends I have made on the way :)
So I talked about the how...but why did I choose to go into science in the first place? Relocating to a new country isn't a small decision and not an easy one.
Since I was a kid, I was always captivated by crystals. Their shape, the colour and multiple varieties. I had a small collection going at one period of time. But it was only a passing fancy, one that I didn't think about again until the final year of university. https://t.co/VEiXECsu0t
As I mentioned, I took a solid state chemistry course which introduced me not just the beautiful macroscopic properties of crystals, but the hidden atomic patterns which lay within and how #structure determines materials #properties.
I began studying a class of materials known as A-site deficient perovskites and used X-ray and neutron #diffraction to understand how the structure impacted the #lithium storage ability. Materials which can reversibly store lithium could be used in rechargeable Li-ion batteries!
A real highlight from these early days was seeing that yes, lithium does rapidly insert into this material creating a dramatic colour change. A simple thing but it really blew me away back then. I then had to understand how ions are transported through solid materials. https://t.co/V7whjPnm0l
I began to construct "batteries" (they were a bit...rough 😅) which enabled simultaneous diffraction experiments to study how the material changed during lithium insertion. (I am happy to say I am much better at designing these batteries now 😁) https://t.co/FcQyK1qcz3
The ability to watch how the atomic structure changed during the electrochemical process was fascinating to me. It was a kind of X-ray vision🙃. This was what set the stage for my persistent research theme of studying crystalline materials under change.
The deeper I went into studying how structure influences properties the more fascinating it became. It became clearer how one could modify and engineer new materials for actual applications. https://t.co/7S6hEWvVEQ
Finally, the raw problem solving that one encounters in research is addictive. I lived for working through a challenging problem, deconstructing the components and putting everything back together again into a coherent story.
After four years of independent research and personally experiencing the joy of discovery, I couldn't just leave it behind. So I took the dive to come to Sweden to continue in research and actually learn a thing or two about batteries.
Ok so I have now talked about the how and why of my research path, but now I think it is time to introduce the "what". What exactly am I doing?? This will be a brief overview as I will dig into the details during the week. https://t.co/pDjVdXieXT
As mentioned, I like to study crystalline materials as they are changing. This change could be during synthesis, when the materials are being utilised in a battery or when the materials have been accidentally left out on a bench and slowly degrading
To study these changes I use diffraction. In this experiment, X-rays (or neutrons) are directed at a crystalline sample. The X-rays scatter from the array of atoms in the sample forming an interference pattern. From the pattern we can determine atom identities and their locations
For example, below I have a series of diffraction patterns collected during lithium insertion and extraction from a material. You can see the peak shift corresponding to a volume expansion and contraction. Copper is present as an inert current collector so it doesn't change https://t.co/7onRjawAOV
That is my main methodology, the materials which I investigate are known as rock-salt derived oxides and Prussian blue analogues. Rock-salt derived oxides are a class of structure that most commercialised cathode materials for Li-ion batteries adopt. https://t.co/k4hIlGo6yG
Finally, Prussian blue analogues are a class of porous framework materials based around transition metals bridged by cyanide ligands. They have an open structure making them ideal for the larger cations utilised in sodium and potassium ion batteries https://t.co/J9YYmOzj6B
Over the next few days I will describe how we study the material changes during synthesis, storage and battery operation using advanced in-situ and operando diffraction techniques. The end goal being to design greener materials which lead to better performing batteries!
Last post for today, what I do occasionally in my free time, when I have free time. Is play table top role playing games like Dungeons and Dragons! https://t.co/ATETutZtlg
To get into character I have a hat that I wear during the sessions😋. It is "role play lite", but its a good excuse to wear my Akubra and put on a ridiculous Australian accent. https://t.co/212ePIqckd
@jkj_2309 No points spent on strength. As a halfling I am all but useless for any kind of physical activity :p
@jkj_2309 Ah, the old glass cannon
Good morning everyone! Today is fairly quiet in the morning so I will take the time to introduce you to the lab and to some of the work that @ashok_menon12 has done. Then I will have a 5 hour workshop for @Altris_ab so will need to drop out early for today
But first, I think it is good to generally introduce what a Li or Na-ion #battery is built up from. While I am not an electrochemist by any stretch, I do work a lot with batteries and will mention them often.
A battery is comprised of four key components. Two electrodes connected to an external circuit: a positive (high potential) and a negative (lower potential) electrode. These are electrically isolated from each other by a separator soaked in electrolyte allowing ions to pass. https://t.co/suyzENp5Mq
The electrons pass via an external circuit where they perform work during battery use. Both the positive and negative electrode materials need to accept both electrons and ions (such as Li+) reversibly. Designing materials which can do this is quite challenging.
In modern lithium-ion batteries the negative electrode (often called the anode) is graphite and the positive electrode (cathode) is either a metal oxide with a rock salt type structure or a polyanionic structure, namely LiFePO4 (LFP)
It is interesting to reflect on the fact that the first commercially successful positive electrode material was developed in 1980 (LiCoO2), and most commercial materials today are based on this same structure. https://t.co/eLJuN4hWFY
Aside from LiFePO4 which is quite different, are there no other viable positive electrode material classes for lithium-ion batteries? There are many being investigated but not so many that make the cut for commercialisation.
This seems like a good segue into giving a tour around the laboratories for the @angstromABC. Where there are now roughly 90 people working on improving batteries from fine tuning the components in Li-ion batteries to developing beyond Li-ion technologies (like sodium batteries!)
Ok lets take a look through the @StructuralChem1 lab! Development of new technologies begins with synthesis of new materials. This synthesis is carried out in many of the fumehoods that we have available https://t.co/PWXXdU5rTq
For synthesis of many ceramic materials we share a number of high temperature furnaces with other groups. Including tube furnaces for synthesis under various inert or reactive gases. https://t.co/89Tn20Qv3l
Additionally, a lot of synthetic work takes place inside our gloveboxes which are filled with Argon. Many chemicals we use for battery research (like Li metal) are air or moisture sensitive and so well maintained gloveboxes are a must! https://t.co/Yzlz33Uvyu
Another two Ar boxes, one for sodium work and the PUB box (aka, Polymers Used in Batteries). These are also the boxes where we build our batteries before we test them. Speaking of testing batteries.. https://t.co/o39f4HHylC
We have 100's of channels for connecting batteries. Most commonly we cycle pouch cells (shown in my schematic earlier and in the photo) but also coin (or button) cells and swagelok cells. https://t.co/cR671Mq1Wb
We also have high precision battery cycling equipment as well as ovens for testing batteries at elevated temperatures. https://t.co/ZoQE81Cb4H
You may have noticed the radioactive box in the previous image :). This is where Fe-57 sources are kept after use in our Mössbauer spectrometer. This one was constructed in house many years ago. It could almost go into a museum if it wasn't so useful for us to this day. https://t.co/xTanPtb8Ff
Speaking of instruments, we have access to multiple characterisation methods for understanding the materials we make. Here we have our (old) XPS instrument, used for characterising surfaces and a TGA-MS for studying thermal behaviour. https://t.co/b8mzFMuzRJ
Last but not least we have our diffractometers, including my personal favourite the Stoe diffractometer (shown with the green light) where I do all my diffraction experiments on batteries. https://t.co/IDVOlGbRUH
One thing that I always enjoy about visiting other labs are the personal touches that PhD students or postdocs add to the lab. Especially when they are in charge of running the gloveboxes :) https://t.co/sbkcQ17YyD
And finally, the most important piece of equipment of all. The coffee machine. Here we modified this one to show short clips from Futurama while your coffee is being made 🙃 https://t.co/DyxDq9253Z
So thats a brief run down of the main lab facilities! There is much more equipment that we have access to which is not directly a part of the Structural Chemistry group but we have access to (SEM, TEM etc)
We just got back from a group lunch/farewell to @ashok_menon12. I will use this opportunity to talk a little bit about what Ashok has done during his PhD. Ashok has worked with what is known as Li and Mn-rich layered oxides.
The Li and Mn rich oxide materials are interesting as they have the potential to store a lot more energy compared to regular battery cathodes. https://t.co/QlHZIRrgz5
The reason is due to the excess lithium which sits in the transition metal layer. The presence of Li in this layer creates local Li-O-Li bonding environments allowing of anionic redox due to unhybridised O orbitals. Below I show the regular LiCoO2 (yellow) and Li2MnO3 (purple). https://t.co/BsbGu4Fh6U
However, this excess lithium has other structural consequences. Namely, the formation of a hexagonal arrangement of cations in the transition metal layer. https://t.co/kD8tTwxknR
However, how these layers in the structure arrange can shift. Leading to a kind of disorder known as stacking faults. In the clip I represent Li and Mn environments as hexagons. The shifts show how two adjacent layers can be placed relative to each other. https://t.co/zcNvFrysnf
The question that Ashok aimed to answer was how the synthesis route impacted the degree of faulting and properties in the relatively simple compound Li2MnO3. https://t.co/wNeSyuxIa6
It turns out that the synthesis route did have a significant impact with a solid state "shake and bake" route producing a mix of faulted and unfaulted structures and the solgel route forming a more homogeneous structure.
We didn't know it at the time...but this would be significant foreshadowing for what would become the theme of his whole PhD thesis. More on that soon https://t.co/h88y0BNDoe
Also! Big announcement, I just got officially promoted to Associate Professor today! What does this mean? Finally it means I have a permanent position 🥳. https://t.co/u6k2ZqHNA6
Now, I need to transport myself to the @Altris_ab offices for a workshop on our market strategy. This will be a long one so I will sign off for today and return tomorrow with more on the Li and Mn-rich oxides and then the core concept at Altris: Prussian blue analogues
Good morning all! Slower start today since I was working late yesterday. That means homemade granola with yoghurt and coffee to get me going https://t.co/GAHakpPm3X
Today I will wrap up the story so far about the Li and Mn rich positive electrode materials before moving onto talking about Prussian blue analogues! Their history and a bit about how @Altris_ab came to be. Stay tuned!
[admin] "Embracing Change - Materials for Greener Tomorrow" Extended conversation with the amazing @willrbrant1 is out now. 🥳🎙️👇 https://t.co/oY7fa0pkdq
After our initial work on Li2MnO3, we discovered that there was a debate in the literature for a related compound. The more promising Li1.2Mn0.54Ni0.13Co0.13O2. It is the Li and Mn rich analogue to the Li[NiMnCo]O2 oxides used in commercial batteries.
What was this debate? It was whether the material existed as a solid solution or if it was an intergrowth or mix of Li2MnO3 and Li[NiMnCo]O2. Ie, if the composition crystallised as one or two phases. Here is an excerpt highlighting the debate https://t.co/rNJ2ihG8uY https://t.co/aTr4I7Sr8J
And here is what the two proposed models are. In the multi-phase model the hexagonal ordering occurs exclusively for Li and Mn whereas in the single phase Li in the transition metal layer can also have Ni and Co as nearest neighbours. https://t.co/X1ch7X4gcN
Why does this matter? It has been argued that the additional capacity, specifically the anionic redox capacity, originated from the Li2MnO3 phase. Thus, its presence is necessary for that additional capacity.
So why is this so difficult? Surely a diffraction experiment can tell you whether multiple phases are present. Lets play a game of spot the difference🙂. Below are diffraction patterns (X-rays and neutrons) from a confirmed "single" and "multi" phase samples https://t.co/wDCj3VYNSu
Aside from intensity differences in the neutron diffraction pattern, they look pretty similar. Figuring out this puzzle is further complicated since the compound has disorder over several length scales. Short to long: Atomic site mixing, stacking faults and phase segregation https://t.co/3mKL1M8idR
Disorder over multiple length scales means to answer this question multiple characterisation tools are needed. This is what we did, looking at both local and long range information. The methods were diffraction, raman spectroscopy, magnetic susceptibility, and STEM measurements https://t.co/Ly1atHr4tA
What did we learn? Is the material one or two phases?? The answer is: both and it depends on how you synthesise the material. Similar to the first paper, solid state gives an inhomogeneous distribution of elements whereas the sol gel method is more homogeneous https://t.co/tSuRtdUUEI
It is not too surprising that this has led to conflicting results over the years. It does raise some interesting ideas about tailoring phase intergrowth via different synthetic pathways however.
The full story can be found here: https://t.co/GSJts7b2AJ
@realscientists This is actually a great idea, I might have to borrow that one🙂
Now to talk about Prussian blue analogues! To begin I have to tell the story behind them because it is one of my favourite pieces of chemical history. It is a tale of alchemists, theologians, famous paintings and about 200 years of wondering what Prussian blue was. https://t.co/rbeaQIJeEd
It all began in Berlin in 1704 with an enterprising dye maker by the name of Heinrich Diesbach. He was most interested in producing a red dye by the name of Cochineal red lake. The ingredients were iron sulphate, potash and crushed up beetles #alchemy https://t.co/0GxjR9T9AY
But Diesbach was running low on potash. Enter the scene one Johann Conrad Dippel. Master theologian, physician, alchemist. Dippel was captured by the allure of alchemy and like any good alchemist began his attempts at transmuting gold. https://t.co/flKvNWZRGk
This failed, but it did not deter him from making a miraculous "animal oil" and releasing it upon an unsuspecting public. The concoction, distilled from the ground up remains of animals, was so foul it was believed it must be good for you (like any good medicine right?)
What does this have to do with a dye maker? Diesbach is said to have been preparing his dyes in Dippels laboratories. His potash shortage was solved by buying from Dippel. Now, Dippel was not a great alchemist and a terrible chemist so of course the potash was contaminated
And so, unsuspectingly using the potash contaminated with animal remains Diesbach tried to produce his red dye. He did not get a red dye. He produced a very blue powder instead. https://t.co/4Tva0GXC1k
Keep in mind that obtaining vibrant blue colours for paint or clothing in these times was not easy, and not cheap. Diesbach knew this and quickly attempted to recreate the recipe and sell his new blue pigment to the world leading to several famous paintings. https://t.co/Iads1W6V3i
The original recipe called for dried ox blood as a key ingredient. Of course, they can't have known what was really going on at the time because the discovery of several key elements had not yet happened (like nitrogen in 1772). So what did they really make?
The key ingredients are iron and cyanide. The cyanide, which originated from various alkyl cyanides in the animal remains, dramatically changed the reaction leading to what is now known as Prussian blue. But it took a few hundred years to figure this out https://t.co/5zkyzWKRSY https://t.co/rOnZ9EqqKJ
Finally, using X-ray diffraction, it was determined that Prussian blue was a coordination framework compound consisting of iron centers bridged together by cyanide ligands. Each iron can be coordinated by six cyanides giving the porous cubic structure. https://t.co/kL6P23luoa
This was just the beginning. Prussian blue is one member of a family of compounds known as Prussian blue analogues. They share the same coordination environment of CN bridges, but the transition metal can change and the pores in the structure can host many different species.
Many different compositions leads to a variety of properties and applications. Prussian blue analogues are more than just pretty colours. They can be used for treating Cesium and thallium poisoning, CO2 capture, in electrochromic windows and of course, in batteries! (and more) https://t.co/AtYlncEnq8
For more detail on the history of Prussian blue, I recommend the work by Alexander Kraft, who has written a few times on the history of the pigment (https://t.co/is3OMqFpuQ) and also a nice perspective by Andreas Ludi: https://t.co/ogjXNcAWFp
So how about Prussian blue analogues (PBAs) in batteries? In addition to @Altris_ab there are a number of other companies developing this class of compounds for energy storage applications. What makes them so attractive?
PBAs are commonly used as the positive electrode in beyond Li-ion batteries (sodium, potassium). They have an open structure leading to fast cation insertion. Additionally, due to the strong bonding of the cyanide ligand transition metals like iron have a decent voltage output. https://t.co/vjzNrlIjVD
Indeed, the performance metrics of PBAs, in particular the iron-based Na2Fe[Fe(CN)6], are quite similar to those of LiFePO4 (LFP). However, PBAs have the additional advantage of a simple and low cost synthesis making them very interesting to develop cheap sustainable batteries https://t.co/4KDjKd01L3
Also the electrodes cast using PBAs look really nice :) https://t.co/kbwR71naE7
It was the simplicity of synthesis and performance reliability which first attracted @RezaYounesi and his PhD student Ronnie Mogensen to Prussian blue analogues. The full story on this is coming up next🙂
The story of how @Altris_ab came to be and my involvement in PBA research is also a nice one. It was really a combination of the right people meeting at the right time and at the right place.
It began with Ronnie Mogensen, who was working on polymer electrolytes at the time and just needed a reliable positive electrode that was easy to make. He tried NaFePO4 which didn't always function. Then he turned to NaxFe[Fe(CN)6]. This always worked to a reasonable degree
He then stumbled upon a paper where the group of John Goodenough (Nobel laureate in chemistry for Li-ion #batteries) made rhombohedral Prussian white. https://t.co/xdiIwbj6Mj
What is Prussian white? Specifically, when the sodium content in NaxFe[Fe(CN)6] reaches a maximum with few structural defects, the material adopts a white colour rather than its famous blue. https://t.co/n5S7Xv9P02
It also has very impressive electrochemical performance with a capacity around 160 mAhg-1 and an average voltage of 3.4 V. Needless to say, @RezaYounesi was intrigued and wanted to produce the material for his #sodium #battery research.
The problem was the synthesis, which required the use of a hydrothermal reactor with a built in stirrer. We did not have such an autoclave available so he needed an alternative approach.
It should be mentioned that until this stage, most synthesis routes to prepare PBAs for electrodes resulted in low capacities and low reversibility due to the presence of [Fe(CN)6]3- vacancies and water in the structure. So this needed to be addressed
This was around the time that I got involved in the project, purely because I happened to be in the department and eager to collaborate. However, I had some light experience working with PBAs and methods of chemically intercalating materials. So together we devised a new approach
The original idea of the synthesis was to optimise for low vacancies, high sodium content and low water in separate steps with sodium and water contents reliant on a low vacancy content. We split up the process and recreated the result from Goodenough but with simple equipment. https://t.co/Y1jB41yZR5
And here is a picture of the compound before (right) and after (left) the sodium enrichment step. https://t.co/TqIhOWUmn2
Given our success Reza suggested we should patent this, why not? Afterall, in Sweden the researchers own the idea, not the university. Of course we needed to pay for this ourselves but thanks to the generousity of @KristinaEdstrm2 we had available funding to do just that.
So we were pretty happy with managing to patent our idea. However, it was not the end as another chance encounter with Adam Dahlquist from @InnoEnergyEU pushed us in a new direction: Creating @Altris_ab
Adam introduced us to Paul Larsson to take care of the business side of things and we set to work on first creating the company and then taking on the hard work to get into the EIT InnoEnergy Highway® program, which in 2017 we succeeded in doing
This was quite unusual because when we started the application, Altris didn't even exist. But the four of us really believed in the idea. Plus, the willingness to bring in Paul and share the company was positively recieved. Afterall 1% of 1 million is better than 100% of nothing https://t.co/qrPy2cHnkU
Now the real work began. Scaling up production. Here we hired Dr Tim Nordh as our first ever employee and began to scale up the synthesis within the @StructuralChem1 labs. https://t.co/KLGd9tcVV3
We also started collaborating with a local company LiFeSiZE to produce prototype #batteries. https://t.co/WlnLghzmcn
These were extremely challenging years as we were finding our feet as a company, looking for financing, trying to get things right with scaling up the synthesis AND building prototype cells for the first time. Many road blocks were encountered. https://t.co/c7zTutF68i
But we persevered! And very soon out grew the university as we were ready for the next step. Adam Dahlquist joined the company in 2019 and began pushing expansion. We obtained a site for a small pilot factory and then built the place ourselves (or Tim and Ronnie did).
Here is a photo of the team as it was at this stage. It is one of my favourites :) https://t.co/lRomVqPHVC
We had a new challenge to achieve now. Cell producer partners wanted our Prussian white (which we trademarked as "Fennac" and they wanted a lot (or a lot by our standards). 50 kg by 2020 which was 50 times more than we had ever produced before. https://t.co/WRa5ZJzZXj
Of course, then Corona hit. But this didn't slow us down. Altris had won funding from @vinnovase and @Energi_mynd and came out over subscribed in the seed round of investments.
Since then, things have been ever accelerating and now @Altris_ab is working with cell producers in China, India and Europe to bring Fennac based batteries to market.
Phew, so the story of Altris is quite a long one. Looking back its always amazing how far we have come despite the challenges. But we just never gave up. Now that big cell producers are looking to #sodiumion #batteries Altris will be entering a new chapter in its story.
On a totally different note, a silver lining of the pandemic has been that I started to cook a lot more #ChemistsWhoCook. It has become a great way to relax and disconnect after work. https://t.co/Ym3iVFihaY
And done! Just a simple stir fry today but you just can't go wrong with hoisin sauce 😁 https://t.co/NT33HjReAW
Good morning! Today will be a busy day. In addition to wrapping up teaching preparation for the summer, I will be buying ingredients for #Midsummer celebrations tomorrow and getting #vaccinated! In between all this I will talk a little on the PBA activities I have been up to
For now I am heading into a meeting with a summer worker who will be spending the next few weeks building 100s of #batteries https://t.co/QbKCYUrGjH
Back onto the science before I head out for vaccination. How have I contributed to the PBA work? One of the earliest questions we were asked by funding agencies was about the thermal stability of Prussian white. So we dug into this question: https://t.co/7iLq5UUBFU
One of the main concerns was that Prussian white would exhibit thermal stability similar to that other PBAs which have been shown to release CN compounds at around 200C https://t.co/KlwAMyxqVH
What we determined was that if you already have a low vacancy structure like Prussian white, the thermal stability is determined by the sodium content. The more sodium the more thermally stable it is. A bonus result was that the water uptake is also increased for increased sodium https://t.co/MBPRf02PCF
The latter result is important to consider since Prussian white should be used in non aqueous batteries. So removing all the water prior to implementation in a battery is essential. Understanding the material drying parameters has improved our sample processing @Altris_ab
Of course, the thermal stability is highly dependent on the environment and the conditions tested here aren't the same as in a battery. Regardless, relative to other PBAs it seems that Prussian white is more thermally stable under the same conditions. https://t.co/tSDYLlLKB5
Here I made a nice table of contents figure summarising the key take home messages. https://t.co/CoQYz7MS70
Lunch time question to you all! How important do you think understanding visual #design is for scientists? I spend a lot of time making TOC images but am not the best designer :p. Feel free to write your opinion too!
@ChirpDontTweet Yeah, I would tend to agree. You don't have to do much for good data visualisation to raise the quality over what is generally out there. Less is more as they say.
Nice to see that many think its important. Of course when I say visual design I mean data visualisation #dataviz. Presenting data in a way which is clear and conveys the correct message without ambiguity I think is really important
The other aspect related to PBAs in #batteries are their moisture sensitivity. PBAs, like many porous compounds, are hygroscopic and adsorb moisture from the air. For Prussian white this comes with a colour change. Left is sample exposed to oxygen, right is to air. https://t.co/5sYkcA4IQp
This is a little bit of a problem since you don't want water in a battery, this leads to all kinds of nasty side reactions. So how do we solve this? Well, my mantra is if you want to solve a problem you must first understand it. https://t.co/0gnG5FcTTx
The question I wanted to answer, jokingly, was what happens if I accidentally leave my Prussian white on the bench for a month? The actual question was, how does moisture exposure during storage impact capacity fade? https://t.co/m951WWdsIi
It is useful to point out at this stage that Prussian white exists in two forms. The hydrated, monoclinic phase with water inside the pores and a dehydrated rhombohedral phase, which is a slightly collapsed structure. What comes out of a reactor is the monoclinic phase. https://t.co/9XPyzfmqge
When you dry the material you transform to the rhombohedral phase. We exposed both forms of Prussian white to different humidity levels for 7 days. The monoclinic was unchanged up to 75% relative humidity. The rhombohedral degraded heavily. Left: pristine. Right: exposed https://t.co/ElJ5QPnuIv
Not only were the particles visibly damaged, when held at 55% relative humidity for up to 90 days the capacity was found to rapidly decay before stabilising. It also seemed to occur from one plateau only. So we began to dig into the mechanism for this fade. https://t.co/9KazJwMLkj
To cut a long story and complex puzzle short. Using X-ray diffraction, XPS, mössbauer spectroscopy, IR and Raman we determined that the material degraded in two steps. First the reversible extraction of sodium to form NaOH, then the irreversible basic degradation of the framework https://t.co/4SYWRZM5jA
Such degradation is not unknown for PBAs, however, the impact on electrochemical performance had not been quantified before. Follow on studies from this have significantly impacted how we handle and treat PBA material at Altris.
In the kitchen once again! This time I made a vegetable stew with rice, cucumber pickled with chilli and lime zest and a coconut, mint and lime yoghurt 👨🍳 https://t.co/7QpOZTlu4q
@MySci_PK Not at that stage, but its changing quickly
Good morning everyone! Today is a public holiday in Sweden, specifically #midsummer! But I will still be here talking a bit about research but mostly about the activities today!
But before that I want to give a quick shout out to my research group: ie the ones who actually do all the work :). https://t.co/Nou84HaSgH
When I first came to Sweden and was introduced to #swedish #midsummer, I was made to watch this, which mostly explains things: https://t.co/bdSs0n6Un1
Like any good Swedish Midsummer, it is raining today 😅 (its a bit of a running joke that on the day which represents the longest day of the year, with presumably the most sunlight, it rains) https://t.co/Kt5G3Ey8KH
But still preparations are well on their way. This year we will be doing something a little different food-wise. Putting a bit of an asian-fusion spin on the Swedish midsummer classics🙂 https://t.co/6nnBexxFO5
So! Vietnamese style summer rolls but filled with roe, avocado, cucumber, glass noodles and with a light lime soy dipping sauce. Glad midsommar! https://t.co/d58OUPciVh
Good morning everyone and welcome to the #weekend! Typically I try not to work too much on weekends for that work-life balance, especially after a week with 14 hour days. What strategies do people have for trying to maintain the balance? #mentalhealth
For me its difficult because many aspects of my work are things I genuinely enjoy (ie, the science). Occasionally I look forward to the summer vacation period because I can freely work on the scientific aspects of my job without distraction.
But its good to properly rest occasionally, which takes some discipline. Hobbies which keep me physically active like #climbing are particularly good for this. https://t.co/Q58PFKWo4E
I also occasionally go running and listen to podcasts about design like @99piorg, which is a favourite. I love learning about the hidden details all around us and it is totally different to what I normally study.
And of course cooking at the end of the day as I mentioned, is a good way to slowly switch off. https://t.co/ybq4CQggkw
So it has been a while since I talked science. This week we started a synthesis of other PBA frameworks. A running theme for many PBAs is how easy they are to make...and how #colourful they are! https://t.co/XcYIk3fm1L
We also did some soy, mirin, sesame, brown sugar, chinese chive, chilli, garlic and ginger marinated tofu which was grilled. It was a very #vegetarian themed mid summer https://t.co/Zlt7wNNwtD
The other side of my research which I have not talked so much about is development of tools to study structure change in operando. This began in my PhD as I mentioned with cells for X-ray diffraction. I also made #neutron cells together with @NeerajChemUNSW and @Peterson_VK https://t.co/G3Cz5ESWOj
These cells are significantly more difficult to make but definitely worth it as neutrons allow you to track where lithium moves through a crystal structure. This is important for understanding diffusion pathways and sources of bulk resistance in #battery materials
A publication relating to the cell in the picture was published in the Journal of Visualized Experiments which came with spending 8 hours to record a 5 min video😅. It was fun though! Neutron cell designs have improved a lot since this time https://t.co/ZvTEmMBXUI
Since coming to Uppsala I have focused more on battery cells for X-ray #diffraction, and mostly using our in house diffractometer. This has been work I have done for others in the group. Its amazing how much you can achieve without going to a #synchrotron (though I do miss going)
We have studied materials like LiFeSO4F in pouch cells. This was a particularly good success as it is an Fe containing material on a Cu source diffractomerer. This typically means there will be a lot of fluorescence, but the mythen detector can be tuned with an energy cut-off https://t.co/egyuyGrogo
Subsequently, we were able to monitor different phase distributions during fast and slow charge/discharge cycles with a data collection time down to 4 min. Not bad for an old lab diffractomerer! https://t.co/xoN1LnHj8B https://t.co/LfsuAgZoAL
We also managed to run modified coin cells on the in house diffractometer to study Li-S #batteries. Here the stack pressure issue often present in modified coin cells was overcome by utilising Be plates inside the coin cell. Since the potential was low side reactions were avoided https://t.co/WfpaIIVdLE
This was one of my favourites as the #diffraction data was combined with a new method known as the Intermittant Current Interruption technique. Combining multiple data streams allowed unique insight to the mechanisms of resistance increase in Li-S cells https://t.co/U086HrIMgZ
Combining several measurements in one experiment is how I want to continue to develop cells such as these (in house and at synchrotrons). I have a few projects in this area so keep an eye on @willrbrant1 for updates!
@LunchBobs @AcadeNik The Mythen detector is great. We upgraded to a 3K system recently, speeding up data collection times even more. Next major upgrade will be to a dual source with Mo on one side.
Today in #ChemistsWhoCook, I have made a Lebanese salad with baked tortilla bread, chickpeas and harrisa, mixed with orange, tomato, carrot, olives and red onion with some baba ganoush on the side. https://t.co/CDTbUkNrbN
I used to eat out a lot, its really thanks to the lock downs that I started cooking much more. Does anyone else have some good habits they have picked up as a direct result of the pandemic?
@AcadeNik @LunchBobs This is pretty much what we are aiming for too, its a great idea :D. But yes...funding
@LunchBobs @AcadeNik Combined Cu and Mo in one is where its at. https://t.co/s9Bl3AuJoI
So lets talk about getting science funding. I have the maybe #unpopularopinion of kind of enjoying writing grant applications, if I have the time to do it properly. However, a few years of writing and co-writing them soon made me realise it was a little bit like: https://t.co/sj1VOFGUNy
For those of you out there finding yourself needing to apply for funding constantly, whats your opinion of the process.
On the topic of grant writing, a interesting fact about Sweden is that despite being the equivalent of "tenure", I am still largely responsible for funding my own salary. There are work arounds depending on how the larger research group is structured, but it is how it is.
On a positive note though, I did recently recieve some funding from @Energi_mynd through a collaboration with @MPetranikova for a #battery #recycling project. I will be looking for postdoc who is skilled with inorganic synthesis in August. So keep an eye out on my main page!
Almost an even distribution, interesting! I swing a little bit between enjoying and hating it. Having a good idea, doing the background reading and coming up with a solid plan is nice, but too much of anything can become exhausting
It is time to pack away my PC and switch off for the remainder of the day. It has been a lot of fun over here @RealSci_Nano and encouraging for me to increase my Twitter presence again. Come and follow me @willrbrant1 for more on #diffraction and #batteries. Catch you around!
[admin] Huge thank you to William for telling us about the materials for the greener tomorrow. 🥳 Do give @willrbrant1 a follow! Podcasts featuring William are 👇🎧🎙️ Short - https://t.co/iHSjfZlxzL Long - https://t.co/oY7fa0pkdq https://t.co/yTizRYgM0n
Sebastian Maehrlein
[admin] "Shaking Atomic Lattices with Strong Laser Pulses" Please welcome @sfmaehrlein 🥳 Listen to the podcast to know what is coming your way this week 👇🎙️🎧 https://t.co/hurP57P4gg
Good morning/afternoon, folks! I'm Sebastian from the THz Structural Dynamics group at FHI of the MPG in Berlin, Germany. This week, I'll be tweeting about our advantures in the world of #ultrafast phenomena. Thus no n̶a̶n̶o̶ scale, but #pico- and #femto-seconds this time! ⏱️ https://t.co/8jKRyJcCxx
Before we start diving into science, allow me to introduce the team first: I started my research group 1 year ago with this amazing bunch of talented students (Marie, Leona, Max). Since then we are working towards #THz & #MIR control of structural dynamics. Why that? Stay tuned! https://t.co/28Ka3nfFNt
So why *structural dynamics*? Material properties are fundamentally determined by the spatial arrangement of atoms, ions or molecules. If we can modulate this spatial structure on ultrafast time scales, we might control properties on demand or even discover new material features. https://t.co/5jIruHWDsv
@_AFox_ Thanks, very solid question: In the field of laser spectroscopy people loosely refer every faster than a couple of hundred picoseconds (ps) as "ultrafast". What is important here are the natural oscillation periods of elementary vibrations, usually a couple of ps.
And why *THz* or *MIR*? Intense and phase stable laser pulses in the THz to MIR spectral range enable us to directly drive specific resonances on their fundamental time and energy scales. With these, we can control IR-active modes resonantly and Raman-active ones nonlinearly. https://t.co/HaaYTptiQ6
Where to get these high-field THz / MIR pulses from? Unfortunately there's no out-of-the-box laser pointer for that. So one of the main tasks in our group is to keep our big baby happy and running. #Laserlife More lab impressions to come on #LaserLabThursday. @sfmaehrlein Labs https://t.co/QVEPNTm8jl
Day 2⃣ = Bio day 🗓️ In case you are interested in my #AcademicJourney so far and how/where I got excited about the scientific puzzle pieces that lead to the research topics of my group: Follow the stepping stones and mentors of my academic bio in the thread below. 🧵
(I will feed this thread step by step during the course of the day. So feel free to come back for another glimpse from time to time.)
For my first academic steps I moved to @UniKonstanz, where I studied physics at the beautiful lake and close to the Swiss alps. Best choice ever. While enjoying the lake, parties and playing #UltimateFrisbee, I made many close friends. 🌊🥏 https://t.co/kJ3AEEO4eZ
Besides this, I got interested in semiconductor physics and ultrashort lasers thanks to great lectures by T. Dekorsy and A. Leitenstorfer. Moreover, I realized the importance of a good peer group in academia (📢shout-out to my PhiBoyz). https://t.co/saN2BKBFd8
After an internship at @IMRAsales in the #BayArea, I got infected by the #THz virus: For my “Diplom” thesis, I implemented 2D-THz-Spectroscopy to investigate the narrow-gap #semiconductor InSb and the high-Tc #superconductor BSCCO in the @Huber_Group at https://t.co/HtZIeP0NwT
@IMRAsales @Huber_Group 🏞️Scenic loop: Afterwards, I went to @HPI_DSchool for interdisciplinary innovation studies called #designthinking and founded the creative network @wwHarryDo with amazing people. Since then I am passionate about coaching teams and problem solving. Details in the podcast on Wed.🔉 https://t.co/WwMUsyEIVy
Diving deeper into science, I started a PhD with Tobias Kampfrath at @fhi_mpg_de. We had an earlier fruitful collaboration, which turned out as one of the seminal papers of #THz spin control: https://t.co/jG60Pq0Fu6 He was an amazing supervisor and is still a great mentor!
🎓During my PhD, I built a high-field MIR source using dual-OPA-based DFG. Becoming interested in phonons, I focused on lattice-driven spin dynamics and novel light-matter interaction mechanisms to drive previously inaccessible phonon modes. (more scientific details tomorrow) https://t.co/77YBNMdnBH
For my PostDoc, I joined @XYZ_Columbia at @Columbia in NYC. Not because of the most beautiful office view🏙️,but for diving deeper into #MaterialScience and #EnergyMaterials to investigate hybrid organic-inorganic lead halide #perovskites and other emerging #semiconductors. https://t.co/RrL9L0Kg6r
Thanks to my inspiring host X.-Y. Zhu, previous work by @KiyoshiMIYATA_J and financial support by a #FeodorLynenFellowship by the @AvHStiftung, I had the opportunity to hunt for the fundamental mechanism behind the surprising #optoelectronic properties of lead halide #perovskites
After the exciting PostDoc times living in NYC, I got the unique offer to return to Berlin to start my own research group at @fhi_mpg_de in the Department of Physical Chemistry embedded in a collaborative environment of outstanding colleagues. https://t.co/Ca1U5Eiof6
Stay tuned: With this we reached the destination of the rapid bio journey and I'll provide more scientific details about my fields of research and previous works tomorrow. ✍️@sfmaehrlein https://t.co/7pAEioYfDM
[admin] "Shaking Atomic Lattices with Strong Laser Pulses" Extended conversation with the amazing @sfmaehrlein is out now! 👇🎙️🥳🎧 https://t.co/SBWd2157Uc
Can we access novel spin states via specific lattice vibrations? Yes! In the ferrimagnetic insulator Yttrium Iron Garnet, we showed that resonant lattice excitation leads to a transient spin-state of elevated temperature, but yet unchanged magnetization https://t.co/iz61Z7SNmd
Let's kick off day 3⃣ digit three with a few fundamental scientific questions.
How fast is the angular momentum transfer between spins and the lattice? In magnetic insulators, when angular momentum transfer has to rely on spin-orbit coupling, it is slow ~ns compared to the lattice excitation. Thus the intermediate state is determined by constraint heating. https://t.co/CLJTWPm4hg
Thermodynamic picture: A) Lattice heating under the constraint of conserved total spin angular momentum (pot+lid) ➡️built up of "spin pressure" ➡️ B) new state: internal spin redistribution ➡️C) demagnetization via angular momentum release to lattice 🧲 https://t.co/YJjB91BgYb
Okay, #phonon #control seems useful, but what if there's a desired target mode without electric dipole moment for coupling to the #THz field? We found the sum-frequency counterpart of stimulated #RamanScattering to access these previously IR-silent modes. https://t.co/0x6FrEWAIB
The same sum-frequency excitation can be driven by phoNons instead of phoTons via #NonlinearPhonincs: Anharmonic coupling can lead to sum-frequency ionic Raman scattering. Great theory collaboration with D.M. Jurascheck (@NarangLab, prev. @NicolaSpaldin) https://t.co/dk5fqx6JYq https://t.co/OJrsLfzFRS
For more inspiring #NonlinearPhononics see the works by the Cavalleri groups @MPSDHamburg, especially the seminal work by @michael_foerst : https://t.co/P7gJBqiyWm
Day 4⃣: Today we'll start with the exciting und surprising world of ultrafast phenomena in lead halide #perovskites (LHPs). Then we'll transition to a few impressions of our high-field #THz / MIR laser lab. Would love to see your favourite #LaserLabThursday pics from your lab. 📸
The anharmonic, dynamically disordered and highly polar lattice of #LHPs gave rise to #DynamicScreening models to explain their #DefectTolerance and #optoelectronic properties. Thus, their transient polarization response to light and excited charges needs to be understood!💡 https://t.co/ThU6QM50cM
@geuchies Awesome!! I'll continue with Marie and Max operating the high-power kHz system of our THz Structural Dynamics group (@sfmaehrlein ) at @fhi_mpg_de Anybody else in for #LaserLabThursday ⚡️ ?? https://t.co/bmyS42Oprd
@CaboAntonija @geuchies @sfmaehrlein @fhi_mpg_de Amazing! Love that high energy blue.💙⚡️ From Stockholm to NYC: @XYZ_Columbia friends how are your laser colors today? Any other #lasers around the world? #LaserLabThursday
To decode the ultrafast polarization response of #LHPs during my PostDoc @XYZ_Columbia, I developed #2D-OKE spectroscopy: With this, we finally found a unified origin, which explains the variety of complex nonl. polarization signals in LHP single crystals. https://t.co/EdJQCzTRYL https://t.co/Fpzm7o76pJ
🚨 This study should raise the #awareness for light propagation in all sorts of polarization sensitive pump-probe spectroscopies. Especially for anisotropic and dispersive media. Summarized by Lucas Huber's comprehensive #FWM model. 📈 https://t.co/SH4NGWQXcd
Let's finish today's #perovskite section with two of our recent works. Check these papers by F. Wang et al. if you wanna know 1) How to tune anisotropy in perovskites by alloying? https://t.co/wdC30WeidK 2) How a Belgian Waffle made it on a JACS cover? https://t.co/i2OtLObiu3 https://t.co/wOYtzzRShh
@CaboAntonija @geuchies @sfmaehrlein @fhi_mpg_de @XYZ_Columbia okay #LaserLabThursday, here's one of my all time favorites from our lab. 💥Good old plasma generation never get's boring... 📸by @FrauGruetze / https://t.co/L5sdz1JC5b https://t.co/FJJnd0lFSb
It's #LaserLabThursday. Now the fun part begins. Here are a few random impression of our @sfmaehrlein labs @fhi_mpg_de. How's your laser doing today? 📸 #Laser #Physics #Spectroscopy #ScienceTwitter #thzdoesitbetter https://t.co/lQP1HFJB5y
☁️☁️And with a little help of Marie, #SHG in a BBO and liquid Nitrogen we can even see the near-infrared beam path. ☁️☁️⚡️ #Laser #optics #Science #Physics https://t.co/uLhMGikO23
Day 5⃣: For the weekend, let's turn towards work culture in science. What are the most important pain points and challenges that we must improve? Any further suggestions or solutions in the replies? #NewWork #NewAcademia #IchBinHanna
Wow, what a turnout!! Thanks for all the votes. 🙏 Seems the employment situation is a major pain point. As a scientist, I wonder if the replies are a bit biased from the current German academic perspective. I personally will also fight for more diversity and minority support.
Day 6⃣-7⃣: Sorry for being mostly silent over the weekend. At least this weekend, I tried to stick to my own ambitions for a better work-life balance: I spend my time with a bit of urgent work, friends and family; and enjoyed Berlin's culture and summer. #WorkLifeBalance https://t.co/5KohfdT0Q5
Good bye and thanks for joining this takeover. 🙏 Overall, it was exciting, but I'm grateful being a scientist and not a social media influencer. Nevertheless, I feel #ScienceCommunication not only as our duty but also as a passion. Keep following our adventures: @sfmaehrlein ✊ https://t.co/JN80EKC0WJ
RT @RealSci_Nano: Good bye and thanks for joining this takeover. 🙏 Overall, it was exciting, but I'm grateful being a scientist and not a s…
[admin] Huge thank you to @sfmaehrlein for a wonderful week of science, do give him a follow! 🥳 Podcasts featuring Sebastian where he candidly speaks about his science are 👇 Short - https://t.co/lDnJZRCBSo Long - https://t.co/SBWd2157Uc https://t.co/h0oIp56s8Q
Sofia Masi
[admin] "Poker Phases of Pervoskites" Please welcome @sofy_masi 🥳 Listen to the podcast to know what is coming your way this week 🎧🎙️👇 https://t.co/WiJatBe97s
Good morning #ScienceTwitter! I am Sofia, a researcher in the photovoltaic sector, with a good amount of #nanomaterial knowledge. This week I will be the admin of the @RealSci_Nano account! 😎but if you’d like to see more, the rest is up at @sofy_masi https://t.co/VW2AfyiQ2u
“I know not fear, I have my will, Whate'er my whim or fancy be; For me there's no impossible, I order, bind, forbid, set free.” By Miguel de Cervantes - Don Quixote de la Mancha
I am a researcher at @inam. This postdoc choice was a great compromise between what I wanted to do, 🧪 and where I wanted to go. 🇪🇸 https://t.co/CoeIE2rpfk @inam_uji you learn from the wide array of backgrounds that my colleagues have; everyone is happy to share their expertise! https://t.co/CEbewNwyyZ
Usually, for whatever field I’ve #targeted, I would always go where the #action is - but there are often sound reasons (e.g. #personal/#family) why that may be unappealing #geographically, so I adjust accordingly...not bad 😉 🌍🌏🌎Where your best place to work? #worklifebalance https://t.co/ypr8vgklqU
RT @inam_uji: We're hiring! Have a look at #PreDoc position @INAM project title: “Stable hybrid perovskites by control of dimensionality an…
@MPilarLopezVaro @sofy_masi totally agree! if we divide the researchers into Don Quixote and Sancho Panza I would go to the first group 😄
Do you know that I have always lived in places very close to the sea without wanting to? Now I couldn't do without it anymore. 🌊☀️⚓️
👩🏻🔬🧪The five main branches are considered to be #organicchemistry, #inorganicchemistry, #analyticalchemistry, #physicalchemistry, and #biochemistry, but chemistry is everything in between. 🌱☀️🎨💎🥗🧊🧬🦠 #reallab #synthesis #reaction #organicchemistrycaneverything @sofy_masi https://t.co/s5HZtzToyA
📖 👉Something interesting developing in chemistry is the machine learning: https://t.co/4gm3SCcWKz @lonepair And the biomaterials: https://t.co/haXqDhZjai @sofy_masi #readingforpleasure #studytweet #Chemistry #materialsscience #AcademicChatter #postdoc #phdchat #ScienceTwitter
I opted to study #chemistry at University of Pisa @Unipisa 🇮🇹 the city of #Galileo Galilei 🤩, but not only: 💡⬇️ https://t.co/asRcgk9418 #chemistryiseverywhere @sofy_masi https://t.co/UodMegmlNA
History: one of the #scientific #laboratory of #Galileo Galilei? Piazza dei miracoli! 😏🔝 Galileo sensed the #law of #isochronism of the #oscillations of the #pendulum right inside the Duomo: ⤵️ https://t.co/9DJE4ZkGBJ @sofy_masi https://t.co/MIphsRQTTF
History: From the #Leaning #Tower, #Galileo conducted the #experiments on the fall of #gravities. Could you imagine the amazement of teachers and #students of the @Unipisa? #AcademicChatter #Piazzadeimiracoli #Pisa @sofy_masi https://t.co/2UJ9T9yJqg
#Nanotechnology is an interesting and multi-disciplinary area to study, where you work with #physics, #mathematics, #chemistry, #engineering... My research is currently focus on the #perovskite #material for #optoelectronic applications!💡No two days are the same with perovskite! https://t.co/u9SDzFgKnn
RT @KamatlabND: For additional details of Efficiency charts see Photovoltaics Reaching for the Shockley–Queisser Limit @ACSEnergyLett ht…
[admin] "Poker Phases of Pervoskites" Extended conversation with the amazing @sofy_masi is out now. Chekkit 👇🎙️🎧 https://t.co/68LxJ0nvhf
⚛️Pervskite is one of the most sustainable materials for new-generation solar cells and LEDs! #RealTimeChem: perovskites films (brown-black) prepared from salt solutions (formamidinium iodide + PbI2, yellow solution) at low temperatures ( <150 °C) @sofy_masi @MuhammedSalimK7 https://t.co/OwecPGDXaP
@SaeedMAhsan1 @sofy_masi @MuhammedSalimK7 Indeed! 😉discussion about stability will come soon 🔜
Interesting #luminescent #perovskite QDs #3D #printing for Ultrahigh-Resolution Color Displays:⤵️ #nanothechnology #love https://t.co/T1ZRsYZaBo @sofy_masi
...and here #perovskite #nanocrystals synthetizes by my colleague Andrés! #RealLab #RealChemistry #RealScience https://t.co/FDMeIOfV88
@Pucheault_Lab @sofy_masi @MuhammedSalimK7 Perovskite is a versatile material, and Pb can be replaced by other metals, such as Sn. However Sn has the tendency to oxidise from 2+ to 4+ and its development needs more efforts. By the way, the last results are really encouraging! https://t.co/fsr4h7xN0r
@Pucheault_Lab @sofy_masi @MuhammedSalimK7 I believe that apart from the material, it is important also to consider the easy manufacturing process and the scalability.
@Pucheault_Lab @sofy_masi @MuhammedSalimK7 Interesting reading about that: https://t.co/T6U8NeKnnq
@Pucheault_Lab @sofy_masi @MuhammedSalimK7 Thank you for the constructive discussion!
⚛️The #perovskite precursors self-assembly is spontaneous, but this method is far for perfect. There are often #defects which limit the final efficiency. 💡Here the researchers intervened with methodologies to control defects density. #RealtimeLab #perovskite efficiency 20%! 🔝 https://t.co/YgFY3YZy75
☀️In this work we control the SnO2 (electron transporting material)/perovskite (absorbing material) interface to reduce defects and hysteresis of the final solar cell☀️: https://t.co/CC9CQw6YV7 @perla_mendezh @sofy_masi
🔸🔶🔸Structural #defects (halide vacancies, loss of protective capping ligands...) acting as #trap states, limit both #perovskite #nanocrystals #photoluminescence and #stability. 📚In this review, we present the prgress in this line: https://t.co/CqPHCkD1TV @sofy_masi
RT @the_ScienceTalk: Celebration time 🥳 Today we take a moment to all the guests of #UndertheMicroscope podcast in the 2nd quarter of the…
[admin] We are scheduling for August/September ✨ Sign up here 👇 if you want to take over this account for a week and feature on our #UndertheMicroscope podcast series https://t.co/l13z2FGy7Y
[admin] Want to see your favourite materials/nano scientists tweeting from this account? Nominate here 👇 https://t.co/tt1G5OSPNn
⬛️🟨formamidinium #perovskite is stable and #black (a-phase) at high temperature, but at low temperature turns back to #yellow (d-phase), not ideal to absorb light. Reduction of the dimensionality (3D -> 0D) and chemi-structural strategies: ⤵️ https://t.co/ukqnEc6Lkw @sofy_masi
#Additive addition in solution is a fascinated strategy exploited to improve the #stability of the #perovskite film. #Organic molecules passivate #defects by #ions immobilisation and reorientation, by #coordinating Pb or by #hydrogen bonds. @sofy_masi https://t.co/dZPgA8z9LE
⬛️▪️What happen if we blend #perovskite with rock-salt #PbS QDs? 1)The formation #temperature decreases to 85 °C 2)Theoretical analysis demonstrates that induced strain but mostly #surface energy and #chemical bonds stabilise the #black phase🎯 @sofy_masi https://t.co/WUgYfoqyEu
Being present at #events and #conferences is one of the common platforms to #disseminate our #activity and to reach a large public within the #scientific community or #civil society with a lot of fun! #memories from #Europeanresearchersnight2018 😄 🇮🇹 🇪🇸 🇧🇷 🇲🇽 🇰🇷 @sofy_masi https://t.co/hf9fvO0chf
✏️Which is more difficult to consider in your dissemination plan❓ @sofy_masi
RT @MoritzFutscher: Join us at the #PerEmer21 symposium at the @nanoGe_Conf Fall Meeting. The deadline for abstract submission is Septembe…
RT @NienhausFSU: Come and us at the Fall nanoGe Meeting!! #PerNC21 👩🔬🧑🔬👨🔬 Looking forward to some great talks! https://t.co/YUQn0xqU5G
RT @jonathan_deroo: Join @brandicossairt and me at the NanoGe fall meeting in the NCfun symposium. The abstract submission deadline for ora…
💭Before #COVID19 and #online meeting💭 #Conference wasn’t just about joying engaging talks by expert people. This could be combined with a visit to a new city, a trip with colleagues. So many #memories easier to enclose in a #video👇 ✨Hope get back to normal 🔜✨ @sofy_masi https://t.co/Qf8buNuNf2
📚📖📚 “That’s the thing about books. They let you travel without moving your feet.” - Jhumpa Lahiri 🏖for me summer is the best time to #read about #science and not, but I prefer topics other than those I deal with on a daily basis! @sofy_masi https://t.co/bdCruKJdaQ
📚📚📚For teachers who prepare lessons for September about the #physics of #solarcells or for students I would recommend at least these! #whatelse? @sofy_masi https://t.co/DFgXEEkEJE
Thank you very much Pepe!
@knltwr @sofy_masi @juanbisquert @physolcell Great! Thank you so much!
RT @sofy_masi: 🤱👨🍼👨🔬👩🔬 This is the best #synthesis!!! High #yield, total #selectivity and a lot of #joy!!! 💫 #proudmum #proudfather…
Goodbye everybody! It was fun to be here with you in the shoes of a #real #scientist, made not only of publications but of #RealLife! See you soon wherever it is! [as italian at heart...#ForzaAzzuri 🤞🇮🇹⚽️ #EURO2020 ]
[admin] Big thank you to Sofia for a wonderful week of science! 🥳 Do give @sofy_masi a follow! Listen to the podcasts to know more about her research 👇 Short - https://t.co/WiJatBe97s Long - https://t.co/68LxJ0nvhf
Ferry Prins
[admin] "Nanoscale Energy Transport: The Motion Picture" Please welcome @FerryPrins ✨ Listen to the podcast to know what is coming your way this week 🎙️🎧👇 https://t.co/w4YzXGPXbQ
Hi everyone! I´m Ferry Prins (@FerryPrins), group leader at the Condensed Matter Physics Center (@ifimacuam) in Madrid. My group focusses on visualizing the interaction of #light with #nanomaterials. This week I´ll give a behind-the-scenes of the lab! https://t.co/fMdLSk8u5h
so what´s in store? Day1⃣- As tradition @RealSci_Nano, today I´ll give a brief story of how I got to my current position🧑🔬🔬 Day2⃣- Lab tour! and all the ins and outs of how we make little energy transport movies 🎬 Day3⃣- Nanofabrication with nanomaterials...
Day4⃣- Starting your own lab (my mistakes so you can avoid them 😉) Day5⃣- An older topic for me: the fun 🥳 and frustrations 🤯 of single-molecule electronics! Looking forward to sharing some of these things with you and I hope you will enjoy it!
Before starting, I want to already thank my wonderful team @PhoND_UAM cause most of the content will be theirs of course!! 👏 https://t.co/PynWbcBTUb
1/ My academic journey started at Leiden University, in the footsteps of Rembrandt, Huygens, Snellius, Lorentz, vd Waals, Zeeman, and Kamerlingh Onnes… I was just an undergrad in synthetic chemistry, and not a very talented one 😅… https://t.co/cgKNx2TLcL
2/ So, when looking for a PhD, I decided to gamble a bit and apply to physics programs. I got lucky at the group of Herre vd Zant at TUDelft, who was looking to diversify his physics team with more chemistry backgrounds.
3/ The change was tough at first, but you catch on quickly. Years later I told Herre that when he hired me he took quite a risk taking on a synthetic chemist… he just laughed and asked: and YOU didn’t? 😅
4/ My project was on single-molecule transistors stable enough to work at room temperature. So you take a single molecule, place it between a pair of electrodes that are separated by about a nanometer, and then you measure the current through it… at room temperature. https://t.co/GcxIWgOHqM
5/ turned out it was not impossible… just incredibly frustrating to get there. (I´ll tell you all about these adventures on Friday in an extended thread on single-molecule electronics!) https://t.co/ZB3y6X2n5p
6/ The PhD programme at Delft was great. I learned a ton of new skills in low-noise electronics, nano fabrication, programming. On top, different soft-skills courses were organised on presenting and project management. I even got to spend 2 months in Japan at NTT.
7/ I finished my thesis in 2011 and defended during one of those typical costume parties that Dutch universities organise for you. I decided that I wanted to continue in academia but I was also quite sure that I had had enough of single-molecule electronics. https://t.co/0yKiqsaxQg
8/ So, next challenge: finding the right postdoc position while switching fields! Stay tuned for a little thread on my postdoc search...
1/ As promised, thread on the postdoc search and how i ended up in an empty lab in Boston. 1st, the problem we all face: PIs never reply to our emails! Cant blame them, applications come by the dozens and there´s simply no time to reply to all, let alone interview. What to do? https://t.co/eJMMRXa3UC
2/ I´d say just insist, firmly but politely… Seriously, ask any PI and they will most likely tell you that they are always happy to receive reminders! It even shows that you are really interested and not just sending blanket applications.
3/ After a long search I got a job offer from @TisdaleWA, who was just starting his own group at MIT on nanomaterial spectroscopy… Now of course everyone told me, NEVER do a postdoc in a new lab!!! Cause you loose the first year building up… https://t.co/I6SE4hico1
4/ I admit it was a big gamble to join an empty lab, but it all worked out for me and the experience has really helped me later on when I had to build my own lab. (stay tuned for more on this on Thursday, when I´ll post on my experience starting a lab from scratch!)
5/ I had already decided I wanted to try more nanomaterials-related work toward the end of my PhD, with a side project on nanoscale photodetectors using colloidal quantum dots - my 1st project in which things were reproducible (not a single molecule that refuses to sit still)
6/ Colloidal quantum dots (semiconductor nanocrystals) were already the big promise for next-gen solar cells and LEDs at the time… the great benefit is that they change their bandgap with the size of the nanocrystal. (bonus: they look awesome!) https://t.co/2h9KCByQjd
7/ I got to work with a lot of talented people at the Tisdale lab, looking at spatial dynamics of carriers in semiconductors (lots of colorful quantum-dot thin films!). Together with the Bulovic lab we laid the foundation for what is now the field of #transientmicroscopy.
8/ Transient microscopy allows to visualize carrier transport. You create a tiny population of carriers with an excitation laser, and follow how this population broadens using time & spatially resolved detection. Tomorrow I´ll tell all about the early days and state-of-the-art! https://t.co/pUfwmUn83q
9/ after two really great years in Boston, I decided it was time to try and get my own lab started back in Europe. All about that in a next thread!
1/ now on the final hurdles before ending up with my own lab in Spain 🇪🇸… and how it needed a little bit of Swiss🇨🇭encouragement… https://t.co/RihwKrirvq
2/ To start, looking for faculty positions in Europe has its challenges. Unlike in the US, there is no application cycle… jobs can be advertised any time, and anywhere (and sometimes nowhere, you just have to know). That means it can take time… https://t.co/pDPrk3AFfB
3/ and even though I managed to get to some interviews, it just didn’t happen at the time. I almost dropped out of academia but decided to give myself one more chance and took on an offer from @NorrisOMEL at ETH Zurich for a 1 year postdoc.
4/ That 1 year got extended thanks to the @snsf_ch that awarded me an Ambizione grant – a 3 year fellowship for senior postdocs to work toward independence under the wing of a senior PI. (more on my time @NorrisOMEL on Wednesday!)
5/ while not originally in the planning, the intermediate step of an Ambizione suddenly bought me more time to look for that faculty position and gave me already quite some independence. (More countries need such bridging programs!) https://t.co/BjuFaOClfw
6/ picking up the faculty search again, I finally got a tenure-track offer from @ifimacuam - a chance to build up my own lab from scratch! I negotiated to start a year later to wrap things up in Zurich, making the move to Madrid in 2017. (more on that in the coming days!)
7/ I guess what I learned on the job search, is that the standard route of one successful postdoc and then landing your tenure track position is really not the only way to get there. So if you really want that faculty job: don´t get discouraged if things take time! https://t.co/O7IieeqSTV
@GraceCRoberts Thanks! Happy to hear you enjoyed it.
@inaquantumdot Thanks!
That´s it for me for today, logging off early to set up the #merienda for my son´s 5th bday with his friends from school 🥳 Tomorrow I´ll be back with the promised lab tour @PhoND_UAM! https://t.co/IAGApdFcVk
1/ as promised, today a lab tour @PhoND_UAM! In bits and pieces, I´ll give you the ins and outs of our work on visualising energy transport in nanomaterials... First a general tour of our laser lab! 🔬 https://t.co/kgPCNgANaC
2/ Our labs are located at the @UAM_Madrid Cantoblanco campus on the north side of Madrid. We are in the basement, which is really quite convenient when trying to keep sunlight out of the lab (cause sun we have in Madrid 😄🌞) https://t.co/AZH5wvdJqW
3/ The most important piece of optics we have is the 18 m2 L-shaped floating table. This is where we perform all our most sensitive microscopy and spectroscopy measurements. https://t.co/yE5f1LCZOd
4/ we love inverted optical microscopes, cause the exit ports at the bottom allow you to easily couple the light out of your microscope and send it free-space to your favourite detector. https://t.co/m47C25jdUU
5/ many of our ports are equipped with @Thorlabs adapters to directly mount cages, making for easy alignment in and out of the microscope. Here for example, you see the in-coupling of our single-mode excitation laser for diffraction limited illumination. https://t.co/9OIfuih0ZF
6/ we use diffraction limited excitation of our samples to generate the fluorescent signals that give us a ton of info about the material. we analyse these signals using different space, time, and energy resolved techniques. https://t.co/HpbmrKE8HJ
7/ our favorite layout uses relay lenses to project the image onto the slit of an imaging spectrograph. The slit is motorized such that we can either propagate the spectrum to the camera (slit closed, grating in place) or the full image (slit open, mirror instead of grating) https://t.co/KgmNYG12MS
8/ The best part of this layout is that you have plenty of space to introduce for example polarisers, additional filters, or a so-called Bertrand lens that allows you to do angle resolved spectroscopy(more about that tomorrow!)
9/ for spectroscopy, we really like our imaging spectrographs with double exit ports. The standard layout gives you the spectral dispersion directly on your camera (EMCCD in our case). But alternatively, you can send the light out to the side to an avalanche photodiode. https://t.co/NWSxJZVgeV
10/ this gives you the option to do spectrally resolved lifetime measurements... basically it´s very a simple streak camera with a timing of some 100 ps and spectral resolution depending on your grating.
11/ Finally, on the other side of the microscope, we have our scanning avalanche photodiode, which has a ridiculously simple layout, but is the key to all our energy transport measurements. I will tell you all about transient microscopy in a dedicated thread! https://t.co/VWi0CvFUwY
1/ A thread on transient microscopy techniques! This simple technique allows you to visualise carrier transport in a variety of materials, giving direct information about how fast and how far carriers move. (this is going to be a long thread, bear with me!) https://t.co/EZ8vIl8vFi
2/ Understanding carrier transport is crucial for optoelectronics. In a solar cell, for example, carriers need to travel as far as possible to reach charge collecting interfaces. https://t.co/3jnWU1z2Vp
3/ traditional techniques are time-averaged methods that only measure the average speed of the carriers during its lifetime. This works well for perfect lattices of a single crystalline semiconductor where speeds are constant... but not for more complex nanomaterials!
4/ we started working on this problem around 2013 at MIT, with a team of people from the Bulovic and Tisdale labs. The idea was to create exciations in one spot, and detect how long it would take for that excitation to reach a different position. https://t.co/BxShPvKr2s
5/ Gleb Akselrod, a senior grad student at the Bulovic lab, built the first version of the transient microscope, and it was remarkably simple: a fixed diffraction limited excitation, and a motorized APD in the image plane for raster scanning. https://t.co/BMOTPoTeUQ
6/ the excitation spot is kept tiny using a high NA objective (>250 nm), and by scanning the APD across the fixed exciation spot, you obtain a beautiful visualization of the broadening of the carrier population! https://t.co/vspwzIpb5q
7/ if your material is isotropic, a single line scan gives you all the info you need. But as Gleb showed beautifully in the first publication on transport in tetracene organic crystals, different axis can give anisotropic transport. https://t.co/O7liprXJl3
8/ In the tetracene paper, things were relatively easy cause carriers are triplet excitons that live very long and travel far (100s of nm)... but what about single excitons with short lifetimes?
9/ we tested this with thin films of colloidal quantum dots, where singlet excitons hop from one particle to the next through energy transfer. This process is slow, and excitons only live about 20 ns in these materials. The transport was therefore not expected to go very far.
10/ but transient microscopy can measure tiny displacements far below the diffraction limit! This is because you only need to determine the difference between the population width at different times and to determine the width, it´s all signal-to-noise! https://t.co/euf1S93g3q
11/ the precise determination of the width at different times is what allows us to determine the mean-square-displacement (MSD) of the population, and the slope of the MSD tells us how fast the carriers move.
12/ back to the QD thin films: because they are so bright, signal to noise is awesome! So we showed that even the tiniest displacements could be resolved using transient microscopy... travelling just 10s of nm during their lifetimes! https://t.co/paVtwvs0eh
13/ this is a bit short of course for a solar cell, but turns out well for an LED for example. More important was all the info we got from these measurements... cause it turned out the transport was really not your conventional random walk.
14/ As I mentioned, the slope of the MSD tells us how fast the carriers move. If the slope is constant, the speed is constant and we have a normal random walk. But for QDs the slope is never constant and transport is always slowing down (subdiffusion)! https://t.co/zSO0B95eii
15/ Carriers slowing down is a clear indication of a bumpy energy landscape. Carriers start at the top of the hills, move down relatively fast, but slow down as they reach the valleys.
16/ We could relate this directly back to the tiny variations in size of the different QDs, which give tiny variations in the optical bandgap of the particles.
17/ The study on QDs really showed the strength of transient microscopy, cause it turns out that in nanostructured semiconductors, transport almost never undergoes a standard random walk. This technique is what allows you to visualize that.
18/ okay, going to try to wrap up this thread by showing some of the newer developments in transient microscopy. The early days used fluorescence as the probe of the carriers, but that only works for bright materials. What if your cariers dont like to emit light?
19/ the @HuangLabPurdue for example haev pioneered transient absorption microscopy. Rather than looking at emission as the probe, they look at the change in absorption when a carrier is present. An extremely versatile technique! https://t.co/gGOrjJn4BK
20/ and more recently, an interferometric scattering based technique has been developed by the Ginsberg group at Berkeley - an extremely powerful demonstration that really boosts the signal from any carrier! https://t.co/RPVNSfDA7n
21/ sorry for rambling on 😉... I´ll try to find some time later to tell you about more recent work from my own lab, where we use transient microscopy to visualize transport in perovskite materials! https://t.co/CY3RvrAirM
ps: really nice review on the topic is this one by Ginsberg and Tisdale: https://t.co/EiXmyFf1Ll
1/ ok, final thread of the day... let´s see if I can keep it shorter than the previous one 😉... we continue with transient microscopy, but now on the family of 2D perovskites! Specifically, how tiny changes in the perovskite composition have a huge impact on energy transport! https://t.co/v43h5DyQoN
2/ so perovskites are all the hype right now of course, showing really promising efficiencies for solar cells. Main issues that remain are related to the stability and this is where lower dimensional perovskites (such as 2Ds) can help.
3/ using long organic cations, you can cut up the conventional 3D perovskite lattice into layers, forming the 2D perovskite lattice. The long cations protect the soft inorganic lattice from exposure to air and humidity, improving the stability of the material. https://t.co/nTTocmLGGq
4/ but, cutting up your lattice changes everything in terms of carrier transport! Not only do you place these organic barriers there, the confinement of the carriers to a thin plane changes their interaction: free charges become bound electron-hole pairs (or excitons). https://t.co/oydM2yTzfI
5/ so how do excitons move through these layers? Can they move between layers? And how do changes in the composition change the transport characteristics? Due to their tunability, layered perovskites are a perfect platform to study structure-property relations 👌
6/ so first, if we want to study structure-property relations... we need to make different perovskite variations. Luckily, 2D perovskites are extremely forgiving and crystallise very easily from concentrated solutions... you literally see them grow! https://t.co/HDZnyhYvf3
7/ we grow the crystals on glass slides and use good old scotch tape exfoliation to isolate single crystalline flakes large enough for transient microscopy measurements. https://t.co/SrYjJKrNXo
8/ then we run our favorite experiment again, first on one of the typical 2D perovskites, with a phenethylammonium (PEA) organic spacer between the layers. The population of excitons broadens fast, so transport in the 2D plane is efficient! https://t.co/AevUVWdd0G
9/ but what if we change the spacer to another commonly used example: butylammonium (BA)... to our surprise it behaved completely different! https://t.co/MLcgNj8vGl
10/ if we translate it to a diffusion length L_D, it´s a massive difference! Why? Especially considering that the carrier live in the inorganic lattice, and the spacers should have little influence on the electronic properties. https://t.co/KNUK5mvYmu
11/ by exploring more spacer cations, we found that exciton transport scales beautifully with the stiffness of the lattice, showing that exciton-phonon interactions are the dominant parameter determining transport. https://t.co/YYwAT2vwmw
12/ knowing this relation between transport and lattice stiffness, we can now start thinking of designing even better 2D perovskites for energy transport. These results were summarized in the first big publication coming out of our madrid lab. https://t.co/k1laNQIDWs
13/ beyond the clear differences, transient microscopy can also give very subtle info on the details of transport, for example about the types of traps you have in your material. https://t.co/rvscrtX7fm
14/ and how about interlayer transport? Turns out it is really quite efficient in 2D perovskites! https://t.co/FIumX55Jkn
15/ more stories are coming up soon, as we are still exploring the large parameter space of these materials... and other systems are lying on the shelve... measurements take time though, and careful data analysis is crucial in this field!
16/ last week we celebrated the PhD defence of @M1chaelSeitz, who has been the driving force of setting up this work. While it is sad to see talented people go, we can be very proud of the result! Luckily we have a very talented @Alvaro_Mgd who has taken over 🙂 https://t.co/bbGSndN3Et
17/ with that I close for the day! tomorrow I´ll be back her @RealSci_Nano with some nanofabrication of nanomaterials!
[admin] "Nanoscale Energy Transport: The Motion Picture" Longer conversation with @FerryPrins is out now 👇🎧 https://t.co/EseHse1jwg
1/ Today I want to talk a bit about nanofabrication with nanomaterials! We are used to do nanofabrication on metals and crystalline semiconductors, but how to create structures out of softer nanostructured materials? for example, a pyramid from (roughly) 250.000 nanoparticles? https://t.co/JZkHMbsn4D
2/ during my time @NorrisOMEL, we were always looking for new tricks to structure optical materials and improve their photonic properties. The specialty of the group was (and still is) a technique called template-stripping, but till then was mostly used on plasmonic metal films.
3/ template-stripping of metallic films was developed by David Norris together with Sang-Hyun Oh (@OhLabUMN) during their time together at Minnesota. It´s an amazingly powerful and simple technique to create extremely high quality structures! https://t.co/b39WZLdmkL https://t.co/pFt5S6CPij
4/ You start with a simple Si wafer, and do your favorite patterning (litho&etch) to create what we call the template. You then evaporate your material onto the template and glue a glass slide (UV epoxy). Final step: you separate the glass slide with the metal from the template. https://t.co/e0ZL9NfrSc
5/ the beauty is that now you have exposed an ultrasmooth, patterned surface! While the evaporated metal film has nm-scale roughness, your stripped surface is as smooth as your silicon template. For plasmonics this is essential: any roughness can scatter your propagating plasmon.
6/ ok, back to the patterning of nanoparticle films... can we use template stripping to structure thin films of colloidal quantum dots for example? The problem is that when your materials sticks too much to the silicon, the stripping gets ugly.
7/ then we remembered this really nice paper by Lee et al., in which they make a silicon wafer super non-sticky (extremely hydrophobic) to QDs using a dense self assembled monolayer (SAM). https://t.co/Bif2XsbOXC
8/ so, template stripping of QD thin films using a template with a SAM? Works beautifully! drop cast your solution onto the template and just clip it of... https://t.co/ABkhznOg5k
9/ here are thin films of different colors of QDs, stripped from their templates shown on the left. https://t.co/ofnZxwJzlN
10/ First structures we tried were simple gratings out of QDs, which would allow you to couple light out of the film more easily. This SEM image shows nicely the arrangement of particles for a 400 nm periodicity of a grating. https://t.co/3DURqt4tql
11/ so why the grating? Cause it can help the outcoupling of emission from the film. For a flat film of QDs, a lot of light get´s trapped into waveguide modes due to total internal reflection (a problem of momentum mismatch). This can be as much as 80% loss! https://t.co/Nzu3aQzw3C
12/ the grating creates Bragg scattering at the interface, giving the waveguided light a bit of extra momentum that helps it to couple to free space. by changing the periodicity of the grating, we can control which wavelength couples out under which angle. https://t.co/qDI5CLi1gR
13/ here you can see circular gratings of different periodicities (pitches), where the red emission couples out under a straight 90 degrees angle for a periodicity of 400 nm. So, patterning is a great way of improving the brightness of your QD film! https://t.co/gt1VQeALm3
14/ we did a bunch of other demonstrations, mixing different colors, and making the patterned films on flexible substrates. https://t.co/BhDkolaDqf https://t.co/KSrIgN06LD
15/ beyond gratings, you can also make waveguides out of QDs, and this turns out to be a great way to make a ring laser! here you can see the transition from just waveguiding to the lasing action at higher pump fluence. https://t.co/F4z24qtBaF https://t.co/WGmY627O1L
16/ the nice thing is that the template stripping can also be applied to other solution processable materials. Here an example of patterning of a perovskite thin film with feature sizes below a micron! 👇 https://t.co/060vf8pLEd https://t.co/8QqQPioxHq
1/ so as I mentioned earlier, when we pattern the surface of a thin film of quantum dots with a periodic grating, we can control the angle of outcoupling of the emission. So how do we measure angles? A small thread on angle-resolved microscopy! https://t.co/HhXVfPgkz9
2/ let´s think for a second about how an objective works: it collimates a cone of angles. This means that the so-called back-focal-plane (BFP) of the objective is a map of all the angles of the light! This is the basis for BFP imaging (aka fourier or k-space imaging) https://t.co/JXsz6n33IB
3/ the size of the BFP is given by the NA of the objective, and translates directly to the k-vectors (or angles) of the collected light. The larger the NA, the wider your angular map you can obtain.
4/ but how do you get this map? For this you need to introduce a Bertrand lens into your optical path. This sounds like a magical piece, but is just an ordinary lens placed at the focal length from the fourier plane of your collimating lens. https://t.co/FXikaEBJrf
5/ flipping the Bertrand lens in and out in this configuration allows you to switch immediately from a real-space image to the fourier image. there are many guides online, particularly good is this one by the group of Rashid Zia: https://t.co/EoR8DhoLhT
6/ you get beautiful images of the angular emission patterns of your samples. In our case with the patterned circular gratings of quantum dot thin films, the right pitch gives a beam of light at perpendicular angle, while other pitches couple at higher angles giving donuts. https://t.co/no84Y0dHDl
7/ it gets even better if you project your fourier image on the entrance slit of your imaging spectrograph... by dispersing the angular pattern you get direct access to the photonic band diagram of your structure! (shown here for a linear grating) https://t.co/hIHpWqPeUF https://t.co/k5Nip6beFT
8/ so check it out, cause angle-resolved microscopy and spectroscopy are really not as difficult as it sometimes sounds (I was surprised how easy it was when I first set it up). You can get a ton of extra info about your samples!
9/ further reading: another really nice reference on this is from the group of Femius Koenderink @_amolf, where they set up angle-resolved microscopy with polarimetry. This paper contains a ton of nice technical details to help you. https://t.co/uqXFtBEIkp
10/ another favorite of mine is this paper by Schuller et al on the measurement of the dipole orientations in 2D materials using angle-resolved microscopy: https://t.co/PoAXH25Gae
Tomorrow @RealSci_Nano: Things I learned starting a new lab! (or basically, the stuff you wished they told you before accepting that faculty job 😱😄) https://t.co/rAVAAZZwpJ
1/ Today: things I learned building up a new lab! Things I was told by helpful seniors beforehand 🙏 and things I wish I´d known 😬 parts of a long thread along the day: 1⃣-before getting started (negotiate!) 🤝 2⃣-all things purchasing 💸 3⃣-staying sane ❤️ Part1⃣coming up! https://t.co/v9yrelQGMa
2/ Part1⃣-before getting started (negotiate!) 🤝 When you finally get that precious offer the temptation is high to just accept and jump right in... but no need to rush🙂 In many cases there is a ton of things to negotiate. Some examples of things I´ve come across👇
3/ Part1⃣-before getting started (negotiate!) 🤝 👉 Most importantly, you can often negotiate your starting date. If you still have a year left on your PD, just wait! It´s precious time to wrap up things and start preparing construction of your lab and team. https://t.co/gPTjhi0qr3
4/ Part1⃣-before getting started (negotiate!) 🤝 👉 now, salaries and startup packages can often not be negotiated, but some places do give a relocation package if you (and your family) are coming in from abroad. Worth checking.
5/ Part1⃣-before getting started (negotiate!) 🤝 👉 absolutely critical is to get as much lab space as you can at the beginning. It´s the only time you can get space without going having to fight a massive department battle! Be generous on your estimates!
6/ Part1⃣-before getting started (negotiate!) 🤝 👉 if they are constructing a new lab for you, dont rush it! Of course you want the key as soon as possible, but an incomplete lab costs you time later on. Ask for all the connections and gas lines you may need!
7/ Part1⃣-before getting started (negotiate!) 🤝 👉 similarly, check what can be included in the construction budget. Getting fumehoods, exhausts, safety measures included saves money on your startup package (I´ve heard some people getting even laser tables included 😉)
8/ Part1⃣-before getting started (negotiate!) 🤝 👉 important: if you already owned some equipment at your old institution, negotiate that your new employer pays for the shipping and possible amortised cost.
9/ Part1⃣-before getting started (negotiate!) 🤝 👉 If you are planning to use a specific facility at your new institution a lot, you can sometimes negotiate a discount or even waiver of the user costs for your group. This can save you a lot of money in the long run!
9/ Part1⃣-before getting started (negotiate!) 🤝 👉 Negotiate your teaching load! Especially in the first year. You´re going to be overwhelmed just with building up everything and getting settles. Less teaching hours or even a complete exempt year can help a lot. https://t.co/19VsjIYc7k
10/ Part1⃣-before getting started (negotiate!) 🤝 👉 If you are on a tenure track, get as clear as possible what are the conditions for your tenure evaluation! It may seem far away, but surprises halfway can cause huge amounts of stress toward the end.
11/ Part1⃣-before getting started (negotiate!) 🤝 👉 Finally, if you are moving to a new location with a family, try to get support for the job/school search through your new employer. In some cases, the university can even find direct employment for your spouse!
12/ Part1⃣-before getting started (negotiate!) 🤝 OK, these where the things I could think of. if anyone has more tips (or questions), please share them in the comments! I´ll be back later with the next thread... navigating the madness of purchasing an entire lab from scratch!
13/ Part2⃣-all things purchasing💸 This 2nd part is all on purchasing, which can be one of the most overwhelming things in the beginning. So now you have this start-up package - how to spend it without going crazy (and how to save some money along the way) https://t.co/R8rrsimO7q
14/ Part2⃣-all things purchasing💸 👉 vendors are your friends! Explain them your plans and let them think along. They can come up with surprising or innovative solutions! A state-of-the-art solution can give you advantage over the competition.
15/ Part2⃣-all things purchasing💸 👉 Vendors are your friends, but please negotiate prices for everything, big or small! You´d be surprised how much margin there is... I´ve seen discounts up to 50% on big items. Play hard-to-get! https://t.co/ImkxjAFm9P
16/ Part2⃣-all things purchasing💸 👉 know what equipment more of less should cost before negotiating. Prices are never listed, so talk to colleagues to get ballpark figures. "What´s your budget?" is the first thing a vendor will ask, and you better give a smallish number😉 https://t.co/uK4go6JpAx
17/ Part2⃣-all things purchasing💸 👉 as with all bargaining, discounts get bigger when you buy in big quantities, so if you can combine different pieces of equipment into one big order from the same vendor, you may save money.
18/ Part2⃣-all things purchasing💸 👉 I personally dont like to micromanage, but for big purchases it´s critical! I´ve lost months on some purchases because the paperwork of the public tender got messed up. Admin can be complicated, ask for help to seniors with experience! https://t.co/ar1ERnAxnK
19/ Part2⃣-all things purchasing💸 👉 for capital equipment, local service beats the lowest price. For example, dont buy a glove-box if the vendor cannot guarantee a local service engineer. Flying in the engineer for repairs can cost a lot in the long run!
19/ Part2⃣-all things purchasing💸 👉 same thing with the delivery... ask for details before buying! You´ll regret the moment they drop a massive crate on your doorstep and run off... (though it gives you awesome stories to tell when you´re older 😉) https://t.co/oUkQQS8ViW
20/ Part2⃣-all things purchasing💸 👉 same thing with the installation... I had one vendor deliver me complex optical equipment and tell me I probably knew better than him how to align it... he was not my friend anymore after that 🤨. Make sure things are clear before buying.
20/ Part2⃣-all things purchasing💸 👉 new lab discounts!!! yes, this is a thing. If you´re planning to spend a lot of small items with one vendor, they sometimes offer a new lab discount (usually 5-10% for a year). This is awesome!
21/ Part2⃣-all things purchasing💸 👉 academic discounts!!! yes, this is also a thing. Some places offer you academic discounts, cause compared to industry, we are relatively poor. Just ask!
22/ Part2⃣-all things purchasing💸 👉 check out the local workshop and make friends there! here @UAM_Madrid we have a great glass blower that only charges the raw materials... your Schlenck line is suddenly a 10th of the cost! Same for electronics and vacuum pieces. https://t.co/kuv8ou0lR2
22/ Part2⃣-all things purchasing💸 👉 finally, talk to your admins to set up a good work flow of invoices and payments... it´s the only way to stay sane through the purchasing storm at the beginning... more on staying sane in the 3rd and final part of this loooong thread 🙂
this story comes with more ancient pictures that I´m sure @TisdaleWA can also appreciate 😂 👇🧵 https://t.co/DPDqKbIqzK
so we had a massive four-glove glovebox, dropped on the other end of the infinite corridor @MIT... and while we managed to drive it on its casters all the way to building 66 (2 hour scenic tour)... https://t.co/i6mlG7mrtC
it didnt make the final turn because the cooling unit stuck out too far... lessons learned: clarify the delivery conditions 🪚😌 https://t.co/IUOf1DqQaz
23/ Part3⃣- staying sane ❤️ Perhaps the most important part of this thread: how to manage stress and not underestimate the risk of a burn-out when starting your faculty job... https://t.co/8xKoMHnhxp
24/ Part3⃣- staying sane ❤️ 👉put priorities, perhaps first get settled yourself. Many of us move to a new place/country for the faculty job... first arrange your housing, school, immigration, make sure you and your family are comfortable... juggling all at once can be too much.
25/ Part3⃣- staying sane ❤️ 👉think on how fast you want to grow your team... getting many people started right away costs a ton of time. It may be good to start small in the first year.
26/ Part3⃣- staying sane ❤️ 👉once you start having a team, dont be afraid to delegate some of the tasks. Dont overwhelm your students of course, but establishing group responsibilities is a great way to involve everyone in the lab.
27/ Part3⃣- staying sane ❤️ 👉a very pratical tool to protect your time a bit: Slack workspaces. You can automatically turn off notifications out of office hours and it clearly separates work messaging from your personal life. https://t.co/qA2ew1xnCD
28/ Part3⃣- staying sane ❤️ 👉similarly, dont be afraid to put out-of-office replies when you take some days off. You´d be surprised how many things already got resolved while you were away 😉 https://t.co/nepJHO86p1
29/ Part3⃣- staying sane ❤️ 👉think of the projects you want to tackle... maybe mix big ambitious ones with some lower hanging fruit. Biggest stress comes often from a lack of output in the beginning. A small methods paper after two years can help a lot 🙂
30/ Part3⃣- staying sane ❤️ 👉finally, and most importantly, surround yourself with people that can support you... faculty colleagues that can mentor you and people outside of academia that you can blow off some steam with. Dont try to do it all by yourself!
31/ Part3⃣- staying sane ❤️ ok, so much for all the unsolicited advice from my side. Starting your own group is a lot of fun, but there can be a lot of stress coming along with the new responsibilities. tldr: Pace yourself 🙂
@AaronSlepkov Thanks! appreciate it and fully agreed. Depending on the country/institution, different rules will apply. It´s worth asking around to see what is common.
@DrEllenLeMosy ouch, that´s an awful way to start... sorry to hear that. Fully agree... dont be afraid to ask for the specifics in writing!
@JoFeanelwa haha... pretty much! (in our defense, purchase was in parallel to lab construction and on the drawings it looked great 😉)
@tracyhle Thanks Tracy! yes, great point... low-maintenance-everything!
@JoFeanelwa yep... it was between the hacksaw or the sledgehammer... as far as I know, 10 years later the box is still going strong! 😉
1/ a change of scenery today, with a thread on single-molecule electronics! My favorite topic during my younger years as a grad student... 👉 take an individual molecule and hook it up to an electronic circuit using two electrodes with about a nm separation👌 https://t.co/LXRiXO7pLy
2/ it´s kind of your ultimate pleny-of-room-at-the-bottom experiment... it´s also pretty much a nightmare of failed device after failed device... 😉 https://t.co/Ex2A3gH840
3/ now, of course you could just use an STM to measure the current through a molecule on a substrate, but for some people that´s not complicated enough: what if you want to make a transistor out of it? - meaning you need a gate electrode as well...
4/ in 2000, in a paper that is one of the true classics of nanoscience, this impressive list of nanoscience pioneers reported on a the measurement of a single C60 molecule in a three-terminal device. https://t.co/gcscd39hGB
5/ the key in this paper was the use of so-called electromigration to break a gold wire into nm-separated electrodes. Like this, you have a planar device that can be gated using a back electrode.
6/ electromigration can be a pretty dramatic though: at very high current density in a metallic wire, the electrons start hitting the atoms so hard that atoms get displaced. It´s well known in integrated circuits as a source of breakdown.
7/ to make nm-separated electrodes more reproducible, feedback control of electromigration was introduced by Strachan et al. This gave gaps that were way cleaner. https://t.co/f5XK0XsDvB a number of such advances allowed us to do the final breaking way more gradual. https://t.co/0T0fHMY4F1
8/ biggest issue was though that gold is not very stable at room temperature - it behaves almost like a liquid at the nanoscale! So unless you did all your measurements at cryogenic measurements, your gap would continue to grow and your molecule would not be able to bridge!
9/ in comes my PhD project @tudelft: can we make a single molecule transistor that is stable a room temperature? So this meant stepping away from Au electrodes... it was not until my final year in 2011 that a completely failed experiment brought the solution.
10/ I was helping a colleague cleaning graphene transistors using the feedback control I mentioned earlier. The surface of graphene can be cleaned at high current densities due to Joule heating. The feedback was to prevent it from blowing up, but this failed at some point.
11/ Just for fun we checked the result under the AFM and to our surprise we saw that a beautiful nanogap had formed, exactly like an electromigrated gold nanogap! But of course, the covalent bond structure of graphene is fully stable at room temperature. https://t.co/QdNIWDGkge
12/ we optimized the feedback, and realized that this was more like "electroburning", making graphene react with oxygen at high temperatures. Still at the height of the graphene hype, the joke quickly became that even burned graphene serves a purpose.
13/ so, long story short, we placed some molecules on our graphene nanogaps and managed to measure some gate modulation at room temperature! All well that ends well, but the four years of blowing up devices that led up to this were not easy 🙂 https://t.co/8bm6Vmp3uj https://t.co/NgCF3lilPH
weekend! so no more science threads... just pretty images this morning! (and dont let work chase you into the playground 😉🌈) https://t.co/SfKd51WDt5
Thanks everyone for a great week @RealSci_Nano! Like a proper Madrileño, I´ll start loading up the car to drive to the coast and avoid the hottest weeks of the year 😅 I hope everyone will have a great, relaxing summer in good health. Dont forget the out-of-office-reply! 1/2 https://t.co/lop1izyTnZ
Anyway, if you want to stay updated on the work of my group, you can fellow me on @FerryPrins, or even better, follow my students on @PhoND_UAM! 2/2
[admin] HUGE thank you to Ferry for a wonderful week of science. Do give @FerryPrins a follow! 🥳 Listen to the podcasts to know more about Ferry's science 👇🎧🎙️ Short - https://t.co/w4YzXGPXbQ Long - https://t.co/EseHse1jwg https://t.co/mlTR3208w3
Yu Kyoung Ryu
[admin] "If you Want to Write a Nanonovel : Scanning Probe Lithography" Please welcome @YuKyoungRyu1 and listen to the podcast to know what is coming your way this week 👇🎙️🎧 https://t.co/Y6Cn3t8otO
This week, I will share with you my academic life @RealSci_Nano 1-PhD at ICMM (CSIC): oxidation SPL 2-Postdoc at IBM Zurich: thermal SPL 3-Postdocs at ICMM (CSIC): oxidation SPL and straintronics 4-Postdoc at ISOM (UPM): graphene for energy #Stay_tuned https://t.co/Y6Cn3t8otO
Remark on the title: "If you Want to Write a Nanonovel: Scanning Probe Lithography" Are you skeptic? FOLLOW the thread 🤭 https://t.co/Y6Cn3t8otO
In 2005, from the group of my PhD supervisor, Ricardo García, the first paragraph of 'Don Quijote de la Mancha', by Cervantes, was written by oxidation Scanning Probe Lithography (SPL) on a 2x4 microns^2 silicon chip!!!!!😮 Image source: https://t.co/Pw0uNmFw9w https://t.co/G4pU3GTnGL
In 2014, the research group that developed thermal SPL at IBM Zurich, earned a Guinness record for achieving the smallest magazine cover!!!! Watch the video!!!! https://t.co/ZCAhARUuX3 https://t.co/Xj2BPwTBGm
Scanning Probe Lithography (SPL) is a family of lithographic techniques, where the chemical or/and physical interactions between an atomic force microscope tip and a sample in intimate contact are exploited to create the nanostructures https://t.co/tMXRtUvxH0
Like Electron Beam Lithography and Focused Ion Beam, SPL is a maskless, direct lithography technique with high resolution capability (sub-10 nm), which can be used in a wide range of applications...Some examples if you follow the thread! https://t.co/vX8xJBrCDC
Metal contacts definition to transition metal dichalcogenide monolayers to fabricate field-effect transistors with superior performances by #thermal_SPL Source: https://t.co/YEPYCOwwag https://t.co/xNXpdzBS3T
High-aspect-ratio metallic nanostructures for optoelectronic applications by #mechanical_SPL Source: https://t.co/gxUznrCxUq https://t.co/kgBnS0gclV
Controlled layer-by-layer thinning of Black Phosphorus flakes by #biased_SPL Source: https://t.co/ZPbMaUxXmp https://t.co/Evb5TEYH9L
Definition of biofunctional arrays of nanodots on a substrate by #Dip_Pen_Nanolithography Source: https://t.co/5jjfXU8Kvi https://t.co/Tx37VN8MK1
@JTrevinoNano Thank you 😆
In the story of my academic life, today: "CHAPTER I. PhD AND OXIDATION SCANNING PROBE LITHOGRAPHY (o-SPL)" If you want to read the chapter, follow the #thread! https://t.co/ROnilpJ4qB
Once upon a time, a Spanish Korean-born Physics student at Universidad Complutense de Madrid earned a FPI fellowship in 2010 to do a PhD under the supervision of Prof. Ricardo Garcia at Instituto de Ciencia de Materiales de Madrid (CSIC) https://t.co/wdchPacmkg
For her was a huge surprise to discover that an atomic force microscope not only could be used to make images and characterize properties of a material, but also as a lithographic tool Image: slide of PhD defense presentation in 2015 (the surprise lasted until then, still lasts) https://t.co/ADEISOQ3W6
During my PhD, I developed my work using the oxidation SPL modality to fabricate nanostructures and electronic devices. In oxidation SPL, the AFM tip approaches to the surface. A voltage is applied between them, within a water meniscus.
The water meniscus acts like an electrochemical cell at the nanoscale. The high electric field formed inside the cell induces the hydrolysis of water. The oxygen species are directed to the sample oxidizing it.
The main parameters to control the width and height of the oxides are the relative humidity, the oxidation voltage and the oxidation time. Source: https://t.co/97MqafyfNp https://t.co/6OV0onUN1A
2013. "Single Nanometer Manufacturing for beyond CMOS devices" European project started. I worked in this project and I could learn a lot of lithographic techniques and be in contact with state-of-the art centres such as IMEC, IBM Zurich and beyond https://t.co/RvfvEEB0mF https://t.co/uNmMcAEwXw
I used o-SPL to fabricate silicon oxide masks on an ultrathin silicon on insulator substrates to achieve silicon nanowires by dry etching transfer (Reactive Ion Etching).
The control of the mask size by o-SPL parameters and the control of the RIE conditions were key to achieve the SiNWs with the highest resolution possible and fully transferred onto the 12 nm thick silicon top layer Source: https://t.co/6OaDR4agsp https://t.co/Ko7wO1VXV2
Different lithographic techniques: photolithography, electron beam lithography, focused ion beam, SPL...can be used to fabricate the same nanostructures o devices. Therefore, they must be compared and position each other in terms of resolution, cost-effectiveness and throughput
I fabricated SiNW-based field-effect transistors by SPL and EBL using the same starting substrate (silicon on insulator) and the most similar geometry possible in order to check if the performance of the SiNW FETs fabricated by o-SPL were comparable to the ones fabricated by EBL
And indeed! After rapid thermal annealing to improve the metal/SiNW contact, the devices fabricated by the two methods behave similarly! Source: https://t.co/Fg6w7bSomx https://t.co/9x5Jj7rTKY
I started to discover also the 2D materials! We performed o-SPL on WSe2 thin layers. We controlled the size of the structures by controlling the relative humidity, the oxidation voltage and the oxidation time https://t.co/07g5WAmXlt
We also discovered that the oxides generated by o-SPL were soluble in water, so after wet etching in deionized H2O the oxides left a groove, since the oxides by o-SPL grow above and below the surface.
We could controlled the thickness of the oxides below the substrate surface as a function of the thikness of the oxides grown above the surface. We exploited this to define isolated high-resolution constrictions in WSe2 thin layers Source: https://t.co/37sdZeoeCe https://t.co/TIISgugyc8
[admin] "If you Want to Write a Nanonovel : Scanning Probe Lithography" Extended conversation with @YuKyoungRyu1 is out now! 👇🎧🎙️ https://t.co/mq39KEPLIo
In the story of my academic life, today: "CHAPTER II. POSTDOC AT IBM ZURICH AND THERMAL SCANNING PROBE LITHOGRAPHY (t-SPL)" If you want to read the chapter, follow the #thread! https://t.co/N6AxqN1cRh
After I finished my PhD, I wanted to continue learning and working on SPL. I had the opportunity to do a postdoctoral stay in the group of Dr. Armin Knoll, the group where the thermal SPL was developed, at IBM Zurich where...
...the Scanning Tunneling Microscope (Nobel Prize in Physics 1986) and the Atomic Force Microscope (Kavli Prize in Nanoscience 2016) were invented!!! https://t.co/Fra3K8Q6Fq
In thermal SPL, a devoted cantilever with three silicon legs that have different doping levels to heat the tip was developed. The technique has a close-loop system that allows the in-situ inspection of the written line and
the correction of the writing parameters for the next line. By this way, the user can monitor the writing process while happening and interrupt it if the patterning will not be successful. Sources: https://t.co/3KjQdkcwd4 https://t.co/D8icGlgb5s https://t.co/cyhB6NGGVA
t-SPL can be performed at ambient conditions, no cleanroom requirements are needed. The main parameters that control the size of the nanostructures are the tip temperature and the tip-sample contact force. Also, t-SPL can be used to do 3D lithography with nanometric precision.
The hot tip can be used to indent resist layers or modify a material directly with the contact. The tip, when is "cold" can be used to image the topography of the written patterns like an AFM. If you want to read more: https://t.co/v0rz7MOfMO
Moreover, in t-SPL there is no need to fabricate localization markers because the topography of the buried nanostructures can be taken with the tool and then, design the patterns on the topo image and then, write the patterns: Source: https://t.co/D3lQCePYWE https://t.co/fVOrT5l8CC
During my stay at IBM Zurich, I studied the writing conditions, the thickness of the imaging resist layer (PPA) and the RIE conditions, achieving the record of resolution in t-SPL up to now: 7 nm wide SiNWs array at 14 nm half-pitch!!! Source: https://t.co/NKifC0TwvY https://t.co/fBqULYZay2
I also participated in the fabrication of the first devices using a mix-and-match or hybrid lithography prototype that the lab at IBM Zurich had developed. Sequential lithographic techniques such as Electron Beam Lithography or Scanning Probe Lithography have a main drawback:
a low-throughput. One of the strategies to overcome this issue is called: mix-and-match lithography. It consists in the combination of two or more lithographies in a cost-effective way, where the smallest nanostructures are defined by the high-resolution lithography and
the microstructures in large areas are defined by the high-throughput lithography.
In my group, a laser writing setup had been developed coupling it with the t-SPL writing setup. By this way, the high-resolution parts were fabricated by t-SPL and the large areas by optical lithography, within a single step, using a single tool. https://t.co/3oapg6sRUn
We demonstrated the fabrication of a set of two silicon single electron transistors in an area of 30x30 microns square in less than 5 minutes. Source: https://t.co/u92t1c4cjA https://t.co/Afmy9or9ZG
Finally, I participated in a nice collaboration with the group of Prof. @MuranoPerez (@imb_cnm). We applied t-SPL in order to create guiding patterns to order blockcopolymer(BCP) domains at high-resolution. Sources: https://t.co/CLAD5FgNvj https://t.co/LfAbmwBAA5 https://t.co/ZX7GohBpaw
Finally...You must know! t-SPL has reached a high technological maturity (it keeps under continuous development), so much that the awesome tool is at the commercial level by @HeidelbergInstr @SwissLitho https://t.co/SyElLYuPSl https://t.co/MdK6TXPQdO
In the story of my academic life, today: "CHAPTER III. POSTDOCs AT ICMM (CSIC): OXIDATION SCANNING PROBE LITHOGRAPHY AND STRAINTRONICS If you want to read the chapter, follow the #thread! https://t.co/37eaiSz70o
After IBM Zurich I came back to Spain and I did first a postdoc stay in the group of my PhD supervisor, Ricardo Garcia, at ICMM (CSIC), to continue working in the systematization of o-SPL on 2D materials, concretely transition metal dichalcogenides (TMDs)
We discovered that o-SPL on pristine MoS2, MoSe2 and WSe2 thin layers did not produce nanopatterns with controllable sizes and geometry (height, depth, width, array of periodic nanowires...) because of the influence of the 2D materials crystal lattice symmetry...
Therefore, we had to grow a thin oxide layer on top of the MoS2, MoSe2 and WSe2 surface by a short oxygen plasma. This thin, uniform oxide layer screens the crystal lattice and allows to control the size of the structures by the oxidation parameters, as expected. https://t.co/7j3VG8Ybex
Since we could now control the patterning of these 2D materials by o-SPL, for example, in the case of MoS2 thin layers, we were able to achieve a sub-10 nm constriction and we developed a process to fabricate nanoribbons based FETs (applicable for all the studied materials). https://t.co/8fiGz796aB
Sources: https://t.co/6RKLYhnw1U https://t.co/ncn98fiWkM
Then, I had the opportunity to do a postdoc in the group of Dr. Andres Castellanos-Gomez, also in the same institute (ICMM, CSIC)
I participated in a review with @Andres_2DMat and @RiccardoFrisen2 about how to fabricate van der Waals superlattices using 2D materials. There are so many ways to modulate the properties of 2D materials😮 Look at this table! Source: https://t.co/7d39tBi9kF https://t.co/69XMvUuI6t
The review also earned a front cover, made by the fantastic scientist-artist @Scixel https://t.co/AH66ki0QC3
I also participated in a work inside the field of straintronics. We modulated the bandgap of MoS2 few layers by biaxial strain. This biaxial strain was induced transferring the MoS2 flakes by dry deterministic transfer (https://t.co/jhvHJT5fqN)
into the middle of a metallic microheater fabricated by photolithography on polypropylene, a polymeric substrate. Under different applied voltages, the current through the microheaters heated the polymer causing the biaxial strain on the 2D material.
The different applicable temperatures induced different levels of strain, which were monitorized as shifts of the excitonic peaks by differential reflectance spectroscopy (https://t.co/4mOLVO6ank). Source: https://t.co/j7J8jYcJm8 https://t.co/lN2KaobxVd
Finally today I am going to explain the current chapter in my academic life. https://t.co/b6oWqen4Y0
I work as a postdoc at Instituto de Sistemas Optoelectrónicos y Microtecnología (Universidad Politécnica de Madrid) @IsomUpm, in the group of ISOM Graphene. The institute is a member of the cleanroom network #Micronanofabs, together with @imb_cnm and @upvntc https://t.co/iqRVhz1iu5
@IsomUpm has a lot of cool instruments to perform photolithography, electron beam lithography, to grow thin magnetic and semiconductor films, to do dry etching, to characterize the materials and devices electrically and structurally... (Just to name a few from the list!!!)
For a person who loves lithography and optoelectronic devices...It is like working in Disneyland!😆
In our group, ISOM Graphene, we work with graphene fabricated by different methods for three main applications: health, ICT and energy. https://t.co/gjx1GSYm2q
I am inside the research line of the group corresponding to graphene in energy applications. (a) We are exploring graphene monolayers as transparent electrodes and active components in solar cells. (b) porous graphene foams/networks for supercapacitors.
We love graphene for energy applications because we believe that this exceptional material can contribute to reach some of the Sustainable Development Goals defined by UN https://t.co/MsIV1W7Yv8 https://t.co/dBPbnpKBJe
I started to work in the group in 2020 just before the pandemic scenario and the lockdown!!
But during this time, I had the chance to read a lot of bibliography about graphene based solar cells and supercapacitors and our group published a cool review on graphene-based supercapacitors. https://t.co/tdHWg1OYCp
It earned a cover, which Andrés Velasco @And95es designed gorgeously! It represents a graphene-foam nanocity 🤣 https://t.co/ylD9HMWRpT
And now, during 2021, we could come back to the labs and do a lot of cool experiments again😎...So stay tuned to see our future works!
With this, I have finished to tell you the story of my academic life. It seems that started with scanning probe lithography to lately, more directed to 2D materials...However, don't think I have forgotten SPL at all! When the love is real...😉
The week has already passed so quickly...Full of stories about scanning probe lithography and 2D materials! I hope you've enjoyed...Stay tuned with new updates! @YuKyoungRyu1 @IsomUpm https://t.co/eremmqqVqG
[admin] Huge thank you to @YuKyoungRyu1 for a wonderful week of science, do give her a follow! 🥳 Listen to the podcasts where Ryu candidly speaks about her research Short - https://t.co/Y6Cn3t8otO Long - https://t.co/mq39KEPLIo https://t.co/2UTuqDUclX
Servet Ozdemir
[admin] "Electron Dances in Atomically Thin Crystals" Please welcome @ServetOzdemiro and listen to the podcast to know what is coming your way this week 🎧🎙️👇 https://t.co/SV2M08Mprj
Hello everybody! My name is Servet Ozdemir (@ServetOzdemiro) and I will be in charge of the @RealSci_Nano Twitter account this week. I hope to keep you stimulated with interesting tweets. Today I will let you know about who I am, what I do and how I got here.
Due to my passion for #physics back in school days, as an undergraduate I have enrolled to a BSci + MPhys degree at University of Warwick (@warwickuni). Here, as I progressed through my degree, I fell in love with solid state physics which has huge overlaps with #nanoscience
During my Master's year at Warwick I was working on fascinating two dimensional electron transport properties of traditionally grown #Germanium #Quantumwells and it was during this project I came across #graphene and the wonderful physics displayed by it.
Following my deep interest in #graphene and #2Dmaterials I have enrolled at Univerisity of Manchester(@OfficialUoM) Graphene NOWNANO Centre of Doctoral Training(@NOWNANO_CDT) where after receiving an initial 6months training in graphene and nanomaterials I started my #PhD project
For my #PhD project I was fortunate enough to work as a student of Sir Kostya Novoselov, the co-discoverer of #graphene. Following on from my masters project, my PhD topic became electron transport properties of van der Waals heterostructures of graphene and #2Dcrystals.
During my PhD I was fortunate enough to be part of the team that carried out first ever systematic investigation of electron transport properties of nanostructures of #rhombohedral #graphite crystals encapsulated by #hBN substrates which made it to @Nature https://t.co/8KSlI4GTLt
Aside from that, I was also involved in demonstration of a novel, CVD grown, hBN embedded graphene quantum dots as vertical tunnelling #single #electron #transistors. https://t.co/QLAgkZ58NK
Another work I carried out during my PhD was demonstration of hBN encapsulated Graphene as a #hot electron #lightbulb in #air. You can check this work out open access using the link below https://t.co/cElxBzhDDg
As well as rhombohedral structural phase of graphite, I also had a chance to be involved in experiments demonstrating a dimensional reduction accompanied #quantum #hall #effect and layer parity in over a 100nm's of hexagonal graphite. This work was on the cover of @NaturePhysics https://t.co/MlfNyA1HqX
You can check this paper out using this link https://t.co/BHqbVWR4YB
Having finished and submitted my PhD thesis, titled 'Electronic Properties of Rhombohedral Graphite' in September 2020, I am currently working as a research associate at the Quantum Photonics Laboratory of Prof. Brian Gerardot @HeriotWattUni
Hi again, its my Day 2 on the @RealSci_Nano account today as @ServetOzdemiro. Today I will give a brief history of the field of 2D materials from a physicists perspective, how it all began in 2004 and where it is now! 🙂
The story begins with the paper 'Electric field effect in atomically thin carbon films' published in the journal @ScienceMagazine. The incredible Sir Kostya Novoselov was able to find extremely thin pieces of graphite crystals down to 1 atom thickness. https://t.co/F7CrZla1Hr
Remarkably, the 1 atom thick graphite pieces, which was dubbed as graphene long before 2004 was isolated using a very simplistic method namely by using the adhesive properties of a scotch tape to detach graphene layers attached to each other by van der Waals forces. https://t.co/TFZzxppuzT
Only a year after the publication of the first paper in 2004, two papers have appeared back to back in @Nature in 2005. The papers reported relativistic nature of the electrons in graphene, with Berry phase manifesting itself in the observed quantum Hall effect.
Here are the links to two papers, first one by Novoselov and Geim from Manchester group: https://t.co/810B1INxjX And the second one by the group of Philip Kim which was at the time at Columbia https://t.co/FQsMfRym27
Geim and Novoselov also in 2005 showed that scotch tape method was applicable to other crystals, reporting isolation of atomically thin layers of Boron Nitride, and Transition Metal Dichalcogenides in a paper titled 'Two dimensional atomic crystals' https://t.co/xX3TRCzkTh
In the coming years, en explosion of research occurred in the field of nanoscience on graphene, which is touched upon on this early review article https://t.co/5KDVS1BpCL
In 2010, just as some were believing that things were saturing in the field, Hone and Dean et al. from Columbia have shown superior electronic properties of graphene when it is on top of an atomically smooth hBN substrate. https://t.co/LFZbPeY8hR
At this point, the field has moved from studying isolated 2D crystals to studies of van der Waals heterostructures of them, showing that by combining crystals with different properties in a specific way, unique physics can be unleashed. https://t.co/yadvmzTajl
In 2013, three groups have demonstrated a fractal phenomenon in the altered electronic structure of graphene (when it's aligned with hBN substrate crystal) known as Hofstadher Butterfly, for which the observation previously required gigantic magnetic fields which wasn't possible. https://t.co/xbMXclr33G
Links to the 3 papers are: https://t.co/X7gtjfKSy4 https://t.co/h7wLFAzl1y https://t.co/71jahZYQiL
Things have also become very stimulating in the field from an #optical perspective when 4 groups in 2015 have demonstrated single photon emission from localized sites in 2D semiconductor WSe2 flakes.
Below are the links to 4 papers: https://t.co/JMyEY4jeHY https://t.co/eEid0miRfb https://t.co/ANAGmay62Z https://t.co/Jc2rzkbA4Q
Despite the observation of many exotic phenomena including Ising superconductivity in MoS2 and NbSe2, no intrinsic magnetism was observed in any 2D crystal ubtil 2017, when a layer dependent ferromagnetism was shown on air sensitive CrI3 crystals. https://t.co/pPeRDiAOGM
The moire superlattice work initially kickstarted on hBN/graphene heterostructures took a completely different spin in 2018 when Herero group from MIT showed superconductivity on the predicted moire flat bands of two 1.1° aligned graphene crystals. https://t.co/r60vhOfFiF
Twistronics, 2D Magnetism and Excitonics remain to be current hottest topics in the field of 2D Materials 🙂.
@igordownunder My apologies 🙏
@igordownunder Below is the link to 5th paper 🙂 https://t.co/kNd9yUJbAJ
[admin] "Electron Dances in Atomically Thin Crystals" Extended conversation with @ServetOzdemiro it out now 👇🎧🎙️ https://t.co/cFGKUcbjzg
Hello, today my Day 3 as the @RealSci_Nano content curator as @ServetOzdemiro. Today I will talk about the fascinating physics I discovered during my PhD on rhombohedral graphite crystals 🙂
Natural #graphite occurs in two forms, which are namely, the Bernal hexagonal stacking and the #rhombohedral stacking which are both illustrated on the picture below. https://t.co/VqlssA2LH2
Due to the Bernal graphite being more energetically abundant, experimental investigations into Rhombohedral graphite were limited to a few layers, until Henni et al. showed rhombohedral stacking on exfoliated graphite crystals up to 16 layers in 2016 https://t.co/942Xz4Dqpt
This was very exciting from an electronics point of view, as rhombohedral graphite thin films are a 3D generalisation of simplest 1D topological insulator system Su-Schrieffer-Heeger chain https://t.co/rkyvC2UHH9
Therefore, being a nodal line semimetal in bulk limit, rhombohedral graphite in thin film limit had flat bands with simplest tight binding calculations suggesting a p^N dispersion, where N is the number of layers, being susceptible to magnetic and superconducting interactions.
https://t.co/ZmcA7f3he8 https://t.co/ArszJbLGT1 https://t.co/jTV7lZSV5r
Plenty of electronic interactions being predicted at the low energy limit, the challenge was to study scotch tape exfoliated rhombohedral domains in high quality electronic devices after encapsulating them with hBN crystals https://t.co/Pv1WB67ZtS
Following finding of rhombohedral domains in hBN encapsulated graphite flakes, electronic devices in form of Hall bars were formed, enabling Landau level spectroscopy in presence of magnetic fields https://t.co/RchEwwaB7C
Following magnetic field characterisation of the samples, aftwr reaching to temperatures down to 10mK, we have found that the electronic structure of rhombohedral graphite films is an N-layer generilisation of graphene, with flat bands being quadratically dispersing https://t.co/9ZOG8FaZPo
Being accompanied by a Berry phase of NPi, the flat bands display a spontenous metal-insulator transition for the case of 9-12 layers of graphene thick samples with magnetic field characterisation suggesting a magnetic nature of the gap responsible for the transition https://t.co/eFlUYV2jX0
Being an alternative to twisted graphene systems, the predicted superconductivity in rhombohedral graphite is yet to be seen. For more details on rhombohedral graphite please look at our paper published last year @Nature https://t.co/8KSlI4GTLt
Hello everyone, for a 4th day content on the @RealSci_Nano account, today I will be tweeting about the work of my current research group, Quantum Photonics Laboratory of the Heriot Watt University, on 2D materials and van der Waals heterostructures.
One of the early works of the group on 2D crystals was demonstration of strain induced single photon emission sites, on mono- and bi-layer WSe2 flakes, on nano-pillars fabricated by e-beam lithography. Here is the link for the paper https://t.co/syOdsQvxQ3 https://t.co/J7Zu9WiT7P
Another work of the group was demonstration of out-of plane luminescent excitons in air sensitive monolayer InSe crystals in contrast to in-plane ones in WSe2 and MoSe2 https://t.co/cnUl4yHK6Z
Utilizing a monolayer hBN tunnel barrier to separate a quantum dot in monolayer WSe2 from a Fermi reservoir in few layer graphene in 2019 the group reported Columb blockade accompanied by spin conserving tunnelling of charges through the hBN https://t.co/uW1mjXhTaJ
In 2020, spin-layer locking on interlayer excitons trapped in moire potentials formed in a heterostructure of bilayer 2H-MoSe2 and a monolayer WSe2 was reported. This lead to two types of excitons with distinct spin-layer-valley configurations. https://t.co/Y9vDDbbnnD
There are currently two preprint on Arxiv about moire trapped interlayer trions in WSe2/MoSe2 heterobilayer and Coulomb staircases in moire superlattice https://t.co/YkqunkQlzz https://t.co/oexCBBiY9T
[admin] Huge thank you to Servet for a wonderful week of science. Do give @ServetOzdemiro a follow! Podcasts where Servet candidly speaks about his science are here 👇🎙️🎧 Short - https://t.co/bKjjJ485JJ Long - https://t.co/cFGKUcbjzg
Said Rahimzadeh-Kalaleh Rodriguez
[admin] "Benefits of Noise" Please welcome @srk_rodriguez for more than a week of science 🥳 Listen to the podcast to know what is coming your way this week 👇🎙️🎧 https://t.co/AkPOXeT8Xf
Heeeeellooooo Friends! Good morning in Europe! Thank you Pranoti and the RealScientists team for having me here. I'm very much looking forward to interact with many of you during the rest of this week and the next week too! https://t.co/ZLFuLOMuTc
ups! I missed the Nano ☺️ dont worry! There'll be plenty of Nano for the Nano aficionados too 😁
Here's my plan for this week. 1⃣ Wed: How did I get here? My personal and professional struggles, and also achievements from PhD and postdoc time. 2⃣ Thu: Impressions from my group, Interacting Photons @amolf 3⃣ Friday: The benefits of noise! 4⃣ Wknd: Amsterdam! https://t.co/JPtduUngkn
Buckle up ! I'll try to take you for a fun ride (of the mind) 😀 https://t.co/yAmvjZe8zY
In this first 🧵 I'' share personal aspects of my life/career, like: - Where I'm from? - What motitvated me to become a scientist? - Struggles with mental and physical health. - Summary of the wonderful places I've lived/studied in while pursuing a career in science https://t.co/MOPj52UJRb
I was born & raised in Monterrey, Mexico. This is a big (~5M people) city in the north of Mexico. It's quite lively and industrial, famous for meat and cabrito (which I dont eat since 17+ years since I became ~vegetarian). https://t.co/hcrrZeZObe
As a child, I endured/survived MASSIVE amounts of bullying. I was very lonely, and I blamed the world for it. I just didnt know any better. After growing up, I realized that I earned a lot of that (without justifying the abuse) via my poor social skills, selfishness, etc. https://t.co/vfTo4wgGa1
All the abuse (emotional and physical) I lived through as a child threw me into depression as a teenager. I literally wanted to die -- every day. But I did not have the courage to kill myself. My parents were very loving & caring. They wanted to help me, but it was beyond them. https://t.co/RudfT91TKd
I went through VERY tough high-school years. I practically rebelled against everything. So I dropped out of University in my first year, and I soon hit rock bottom. After, I dedicated the next 2 years, FULL TIME, to work on my mental/emotional/spiritual health. Lots of therapy!
Those years of therapy were the best time investment in my life. They completely re-oriented me. They transformed me in so many different ways. Eventually it is out of there that my passion for science emerged. I'll continue later as I go for lunch with my group now ; ) https://t.co/srg2WM41UV
After a huge existential crisis, in which I nearly died (literally), I did a lot of soul searching. I devoured texts in the "New age" section. Some of my favorite authors: Eckhart Tolle (The Power of Now), Don Miguel Ruiz (The 4 Agreements), Neal D. Walsch, Carlos Castaneda.
After my soul-searching gave some fruits, I went back to study. Since I ruined my grades during my rebellion, no university accepted me. So I went to a community college. I met a lot of intersting people there, with real struggles. I learned to not take things for granted. https://t.co/SAQ23SVTgZ
I was fortunate to have an AMAZING math and physics teachers. Physics struck a BIG chord in me. Understanding that there are simple principles ("laws") that govern the Universe amazed & inspired me. So, after exploring the inner world, it was my time to explore the outer world. https://t.co/aDRlB61KaZ
I did good at community college. Got top marks, and won the annual award for the best physics student. My father came to that ceremony. He was very proud -- for the first time in many years. So my inspiration for physics +making my father proud, put me on a physics track https://t.co/yNiNanGx0O
Around that time, full of inspiration and thinking that everything is possible for the one that works hard, I decided to work towards my childhood dream: become an astronaut. So I transferred to Embry-Riddle Aeronautical University (close to where NASA launched rockets), in FL. https://t.co/sBnSWY27IL
At ERAU I started as a major in Aerospace Engineering. But I quickly transferred to Engineering Physics a nice mix of basic physics & space systems engineering. https://t.co/QJZ4ccZ8N1
As Undergrad, I did 2 internships that defined my path. First, since I am not a US citizen, I could do nothing space related. Space in US is controlled by government & military. So I went for a 6 months Internship on Avionics Engineering at Continental airlines. https://t.co/2DKTfY9kXm
Being around airplanes, understanding their inner parts and such, was nice and interesting. But it didnt really inspired me in the long run. After a few months of looking at wire drawings all the time, I got bored. So I lined up a second internship. https://t.co/AjrYljgvSs
So I went for a ~3 month summer internship to Fermilab! https://t.co/QXO7MaQlyc 😁 At Fermilab, I worked in the Technical Division, in the Magnet Systems Department. I saw lots of BIG & nice magnets, and learned about flux jumps & quenches in superconducting magnets. https://t.co/22vvNf2Vd4
Fermilab was a beautiful and inspiring place to work at. Such a wonderful community! I met many amazing scientists, including 2 Nobel prize winners (in pics below): Leon Lederman (left) and George Smoot (black suit, right) https://t.co/N2rLndpoPI
The great experience at Fermilab, the closedness (and militarily-oriented) nature of the space industry, plus the fact that the courses I liked most were optics and quantum mechanics (thanks to a GREAT professor, Bereket Berhane at ERAU), oriented me towards physics.
I didnt want to do particle physics, mainly because all experiments were runned by big committees. I wanted to do table-top physics, and control my own experiment. And I was fascinated by LIGHT. So I started to look for nano & optics stuff. https://t.co/WWQOKhHD4l
While searching what to do next, I started a club with friends at university. We built antennas, customized tracking systems for airplanes, and even a cube satellite! I also joined the robotics team, where we built an autonomous airplane. More on antennas later😉 https://t.co/Dr6Z15vP04
Around that time, the US revoked visa of BOTH my parents. And threaten to revoke mine (bc of Iranian links). My mother had cancer, and I had a difficult choice: Visit her & risk not returnung (finish studies), or not? I didnt want to live like that. So I searched outside US.
So I searched for a Masters program in Europe. I wanted to travel, explore new cultures (ones not discriminating against Mexicans & Iranians, both running in my blood), and LEARN everything I could learn about the physics of LIGHT. So I went to Europe. END OF 🧵 https://t.co/64z2GsIBl7
In this 2nd 🧵, I'll share my experience as Masters student in Europe. In 2008, I was lucky to receive a full scholarship for the Erasmus Mundus Masters in Photonics (EMMP); see image below. A BIG THANK YOU to Prof. Roel Baets @RoelBaets -- the driving force behind the EMMP, https://t.co/Z8CHRqleZG
The EMMP attracted students from all over the world, and exposed them to 5 Great European Universities: U Ghent, VU Brussels, KTH, Heriot-Watt, and St. Andrews. I did my first year at KTH, Kista (Sweden). Weather was cold, but people were warm. Many Asian friends! 😁 https://t.co/pKUMErNvae
After a nice year at KTH, I went to a wonderful & educational Summer school at Ghent. GREAT organization by @PhotonicsUGent EMMP finished, but U Ghent and VUB still organize a fantastic Photonic Masters. Check it out if you're looking for a Photonics Masters in EU 😉 https://t.co/7lxo1m0D3r
For my 2nd Masters year, I did 6 months of courses in the beautiful city of Ghent, Belgium. BTW: Stockholm, where I did my 1st year, is also Amazingly Beautiful : ) https://t.co/KZ7RweDViH
In that Masters, I learned a LOT about photonics. They had/have really fantastic professors. Very knowledgeable, approachable, nice to talk with, and with a lot of entusiasm to empower students to learn everything about photonics.
Mid-way in my masters, I needed to do an industrial internship. So I googled "Photonics Internship Europe". The first hit I got was to the website of Prof. Jaime Gomez Rivas, @jaimegomezrivas who would become my most important mentor. He was doing nanophotoncis at Philips!
So in the 2009 summer, I joined the AMOLF-Philips group led by @jaimegomezrivas as an intern, to work on nanoantennas for light! Back then,nanoantennas was a hot topic. We were exploring how we could use them to improve LEDs, in collaboration with Philips 😉 https://t.co/9T02vqBfCY
@RoelBaets @VUBrussel @PhotonicsUGent You are absolutely right. I was too short on the complement list. Prof. Irina Veretennicoff was an amazing & inspriring teacher. I loved quantum & nonlinear optics with her. Also Prof. Min Qiu, Thomas Krauss, Geert Morthier, and many others. A BIG thank you to the entire team.
My summer internship evolved into a MSc thesis. The results led to a patent (owned by Philips) and a publication in APL, ~1 year later, when the patent was filed. I completed the MSc with Greatest Distinction, and co-won the prize for the Best Masters thesis. @RoelBaets 👇 https://t.co/gxOFKUuWOR
The Photonics Masters inspired me. And I loved the research I was doing at the AMOLF group based at Philips. Nano-antenna physics aimed at improving performance of LEDs.👇 So when my advisor @jaimegomezrivas offered me a PhD position, I took it! End of 🧵 about Masters. https://t.co/j155qEmpWh
This 🧵is about my PhD. I worked in the context of an industrial partnernship between AMOLF and Philips, supervised by Prof. Jaime Gomez Rivas @jaimegomezrivas We were based at Philips, but doing nanophotonics and going to AMOLF ~1/week. Those were the 'golden years' 😁 https://t.co/F5fXEfIoNM
Broadly, the goal of my PhD was to find new ways in which nanophotonics could improve the performance of solid-state light-emitting devices. We focused on arrays of resonant metallic nanostructures (nano-antennas), which enhance the light emission from a top layer👇 https://t.co/fUfDiJHF8H
I'll highlight some results, but first an overview of PhD papers: I published 20 articles, including 4 PRLs, 1 PRX, 2 LS&A, 1 Nano Lett, 1 ACS Nano / Phot. etc. In 14 papers, I am 1st or co-1st author. I worked hard, but most important I had an AMAZING team and tech support. https://t.co/vYnJBIdEUa
My first PhD paper was in PRX 👇 We studied metallic nanoparticle arrays supporting collective optical resonances. These emerge from coupling localized surface plasmons to diffraction. We coined the term SURFACE LATTICE RESONANCE, now used by many https://t.co/uUgsDQX4gm
These resonances were actually first studied inthe 80s, by KT Carron et al: https://t.co/gu2SR9F73f ~20 years later, GC Schatz et al. revived interest in them when they found extremely sharp (for plasmonic standards), <1 meV, resonances. J. Chem. Phys. 121, 12606 (2004); https://t.co/7vj4nyCVKi
Few years later came this 👇 important/beautiful paper from the group of Prof. Bill Barnes at Exeter. They reported collective resonances in Au (no data supporting collectiveness) BTW: I highly admire Bill Barnes: Brilliant, playful, & humble scientist https://t.co/BEs6bJ7JnX
So we followed up on that, and published another nice result in my PhD. 👇 We showed (exp+theory) that surface lattice resonances are indeed collective, i.e. their quality factor depends on the number of particles (see legend below) in the array. https://t.co/DAUrQELJHT https://t.co/GWK0ACIkBZ
You may now wonder: Who cares about these collective resonances in metallic nanoparticle arrays? Why was it so important that these resonances )in contrast to localized surface plasmon resonances) are sharp? What are the implications? https://t.co/kgIklvHuAj
Around that time we put a thin luminescent layer on top of metallic nanoparticle arrays supporting SURFACE LATTICE RESONANCES. Lo and behold, the light emission from the layer got A LOT brigher! White spot below is blue laser + yellow luminescence. Diffraction -> small spots. https://t.co/aY0CfsjJo2
When I showed the above effect to my advisor, he got extremely excited. He called the BIG BOSS at Philips, so he could, with the naked eye, see the light emission enhancement from metallic nano-antennas. When the big boss saw this, a LOT (!) of money came in from our research https://t.co/EKKZh9QLAB
With that money, the group massively expanded and deepened on "Plasmonics for Solid State Lighting". The idea was simple: Replace lossy and bulky secondary optics in modern LEDS (see 👇) with metallic nanoatennas! The antennas enhance & redirect light emitted from the layer. https://t.co/6TTLKEGBvj
We published LOTs of nice papers on how metallic nanoatennas can enhance light emission from thin layers. We probed configurations similar to those in modern white LEDs, where a blue LED pumps a yellow phosphor to create white light (blue+ yellow=white). Brief highlights below.
Here we showed how to get direction emission from surface lattice resonances (SLRs) in nanoatenna arrays: https://t.co/7vU1bftP66
Then we published this nice paper (my most cited one) where we showed, in greater detail, the various ways in which metallic nano-antennas could revolutionize solid-state lighting. https://t.co/b4t5skAimn
We also used plasmon resonances to couple into guided modes in luminescent layers. We found👇 how nanoantennas can enhance the light emission (local field at emitter position) despite being nearly transparent in the far field! https://t.co/KzvJXKPU81
Another nice paper is this one 👇 We showed that by breaking the symmetry of the metallic nano-antennas out of the periodicity plane, we could fulfill a long-standing goal in solid-state lighting: Emit light in one direction only! https://t.co/UwwNEINmX8
The above article was published after a LONG fight in PRL, which led to an appeal, which we won. Ironically, after the paper had been rejected 3 times by the Editor, once he accepted it, it was even highlighted in PHYSICS! 😁 https://t.co/6tJO4b3Bad
Shortly after finishing my PhD, our team (Gabriel Lozano first author) reviewed many of the nice ways in which metallic nanostructures can be used for efficient LED lighting. You can check out our article here👇 https://t.co/2ktsOjiSzJ
During my PhD, my interests in fundamental physics grew. One idea that fascinated me if SLRs could condense, like a Bose condensate. Imagine: A BEC lighting up your living room! We didnt realize it, but we first proposed condensation in plasmonics👇 https://t.co/ZOH6l2Mn5f
A few years later, our work led to the observation (led by Mohammmad Ramezani, at group of Gomez Rivas) of plasmon-exciton-polariton lasing!👇 We basically realized a novel laser (with plasmonic lattice feedback) with unusual & interesting properties! https://t.co/QgP4G3ir64
Besides research, I enjoyed doing outreach. My advisor valued that a lot, so I learned. I prepared & presented many demos at conferences, open days, public events, etc. Here I demoed nanoantennas for LEDs at the largest Physics Conference in Netherlands -2014 with @albert_polman https://t.co/0eOUgH4b7P
After 4 years, I defended my PhD at TU Eindhoven. I got 'Cum Laude' (top ~3-5% of PhDs in NL). For the defense, I was fortunate to have amazing paranymphs (like 'guardians' in this ceremony), including Martijn Shaafsma and @sander_mann https://t.co/7RJJ5QxkeA
Shortly after, I was deeply honored to received the FOM Thesis prize - best Physics thesis of the year in the Netherlands. Here I am with the former Dutch Minister of Education, Science, & Culture, Jet Busemaker, handing in the 10k EURO cheque : ) https://t.co/DecqUSQ3dE
The accolades continued. About a year later, I got an honorable mention (like 2nd place) for the Christiaan Huygens prize. This was given to the best physics thesis in the past ~6 years. Here again with the minister, other honorees, and someone from Shell financing the prize ;) https://t.co/YiTvgW6J2l
But all the success in the world means nothing if we dont have who to share it with. This is my loving companion, who supported me in my pains and celebrated my joys. I married her in the 1st year of my PhD. Her name is Marina : ) https://t.co/UyHIjhPVKF
And the ones on the right are my wonderful parents who believed in me when nobody else did (details in my first 🧵) I owe everything to them! https://t.co/pdb1seesjC
I would like to end this 🧵 with a pic from the group where I did my PhD. I am so grateful to my advisor, Jaime Gomez Rivas, @jaimegomezrivas, who taught me a LOT about being a scientist. The most influential person in my academic life for sure! https://t.co/HVLpEhOASL
In this 4th and final 🧵 for today, I will share with you my postdoc experience. During the PhD, I became very interested in polaritons: hybrid light-matter quasi-particles formed by strong exciton-photon coupling in a cavity. I copied the animation below from @lagoudakis_p https://t.co/RCYa2Zk7Y6
So I went to one of the best experimental groups in the world of polariton physics: The group led by Jacqueline Bloch and Alberto Amo, at the Center for Nanoscience and Nanotechnologies @C2N_com (back then called LPN) in France. 👇with Jacqueline & Alberto @ Snowbird, USA https://t.co/2dzxMc2wR7
Jacqueline & Alberto were amazing mentors: Brilliant & inspiring scientists, rigorous, creative, and always making nice connections to theorists. They are both SUPER accomplished. Here we are at the ceremony where Jacqueline received the medal of the French legion of honor! https://t.co/e5PEIwsqlX
Shortly after I arrived, I received the news that I was granted a Marie Curie individual fellowship. My proposal received a grade of 97% (!) thereby ranking among the highest of all physics in Europe. The proposal was about taking polaritons a step closer to the quantum regime. https://t.co/ZebNCe5o38
We didnt quite get as quantum as we would have liked😳 Nevertheless, we got several nice results which I will share with you next. I think that' s general in science. "Shoot for the moon, land among the stars". https://t.co/I7uAQmZaX8
First paper from my postdoc: We showed how to control the phase that photons pick, when hopping from one cavity to another, via the incident optical power (effective photon-photon interactions). Check out the phase measurements in there 😉 https://t.co/IqSdXN1LrN
Then came the most extensive & important work from my postdoc: We probed a Dissipative Phase Transition (DPT) of light by measuring the dynamic optical hysteresis of a micro cavity. 👇 https://t.co/AvBuWovAvB https://t.co/70BhmxmONL
A DPT is to dissipative systems what a 'normal' phase transition is to Hamiltonian systems. Instead of the Hamiltonian gap closing at the transition, the Liouvillian gap closes. Its really fascinating physics! A new way to understand phase transitions of open quantum systems.
The physics of DPT and dynamic optical hysteresis has strong connections to the beautiful & universal physics of the famous Kibble-Zurek Mechanism, relevant to many areas of condensed matter physics 👇 Check out our PRL mentioned above for details. https://t.co/IduGaUhkeX
In the experiments mentioned above, noise (fluctuations in light) played a prominent role. This made me want to learn more about noise. Then, I realized that many biological systems USE NOISE TO THEIR ADVANTAGE! 🤯 That powerful realization would re-orient my career, again. https://t.co/MsXoLUTNMo
So I applied for a Veni (a prestigious 'postdoc' grant in Netherlands) on the topic of noise-assisted transport of light, with @AllardMosk and @sanli at Utrecht University. Pic at UU 👇 And I got the Veni! But I didnt stay at UU long. I was offered to start a group at AMOLF😀 https://t.co/XNhtNlAxcn
Before ending this 🧵, I want to express my gratitute to @AllardMosk who was EXTREMELY supportive. I can imagine it was not nice that I partitioned Allard's budget enough so he couldnt hire someone else, yet I didnt produce much. Still, Allard was very helpful and gracious.
So after ~3 years of postdoc total, I got an offer to start my group at AMOLF. I will be telling all about my group @amolf tomorrow Thursday. For today, that's all from me folks! If you have any questions or thoughts about what I shared, I'll be happy to respond to them 😀 https://t.co/l4JAyoJNyp
Hello friends! Today I share about my group at @_amolf 😀 I hope many of you remember AMOLF. Some weeks ago, the fantastic @la_muscarella (who sits down the hall) shared a lot about AMOLF. Next week I'll share some too.😉 Lets start this 🧵with a pic from my group pre-covid! https://t.co/BzIgMXqMQ4
The name of my group is 'Interacting Photons'. Hopefully that tickles some of you. It's "common wisdom" that photons do NOT interact. IF free-space photons would interact, we would see them scatter off each other, like 👇 But we dont see that! Image: Christine Daniloff/MIT https://t.co/2175qOciKn
The trick is that IN NONLINEAR MATERIALS photons effectively interact. To make interactions stronger, we confine the photons to a small volume where the nonlinear material is. We achieve that with a pair of mirrors facing each other, which make a cavity. Our typical system 👇 https://t.co/WTh02CueYT
Yoy may now wonder: Why go through all that trouble *just* to make photons interact? https://t.co/fIwoF2ZEq0
Well, there's really a LOT you can do IFF photons interact. To give you a flavor: Some of the things we look at are novel optical sensors, computing systems, signal transmission schemes , funky nonlinear dynamics, memories, energy harvesters, and more. Ill share that later 😉
But if the above doesnt resonate with you, then this is the killer argument to make photons interact: You can make lightsabers, a la Star Wars! Two of my group members (Falco & Giel) showed how to control one light beam with another in the @amolf open day 2 of years ago 👇 https://t.co/wACM4bjX8k
There are several nonlinear optical materials where photons can effective interact. In my group we use two materials. 1. A drop of oil (like olive, castor, or macadamia oil) 2. Semiconductors (like perovskite, the beloved one of our solar cells friends) Pros & cons below figs👇 https://t.co/Zi1jwJsQMg
I still recall the first time I told my colleagues (and student): Let's put olive oil in the cavity! Everyone laughed 👇 Honestly, I felt uncofortable.🙄 But then it worked !!!!! https://t.co/sd3GGY9Nms
Our first paper with an oil-filled cavity: "Universal Scaling in the Dynamic Hysteresis, and Non-Markovian Dynamics, of a Tunable Optical Cavity". Experiments by Zhou Geng and Calculations by Kevin Peters @KJH_Peters Check it out in PRL: https://t.co/yZVmw2TTCs https://t.co/E0Cvm5zhXC
We made a press release, and the paper received a lot of attention from the Media. We even made it to the BBC 😮 I think a lot of people were fascinated by the fact that something so common --- olive oil --- could shed light on so much interesting new physics. https://t.co/l45N2BW3Xo
Here is a slide I recently made, showing the main topics my group currently works on. Please let me know if you would like to know more about a particular topic, or any questions you may have of what I showed above. Tomorrow Friday I will go in depth into the benefits of noise! https://t.co/wLmFk6EL5F
A pic of a PhD student in the group, Zhou Geng, working in our tunable cavity inside a closed-cycle cryostat 😉 Remember the seminconductor (and the polaritons) I mentioned before? Well, we cool them. To make ithem nonlinear and (hopefully!) quantum. Photo: Ivar Pel https://t.co/FKZkQxNTRX
Here's another pic of one of our cavity setups 👇 This one was mainly built by Masters students from the University of Amsterdam. In the coming year, we hope to use it to measure IF & HOW a cavity can modifty the electrical conductivity of materials 😉 https://t.co/61CFhF3a6B
I'll leave it at that for now, unless anyone wants to know more about my group. Then, I would be happy to tell more.😁 Next week I'll also talk about the "Magic of AMOLF". It's really in the people. You can see it here 👇 btw: someone told me the Sinterklas is a Mexican 😉 https://t.co/rtuCSkUxr1
Hello friends! This tweet 👇, which may resonate with many of us, made me think: What do you think we could do differently in academia to improve this? Clearly, just telling each other to "be nice" wont cut it. Structural changes? Incentives? What do U think? https://t.co/XF4fJxcCLy
@M_LaddParada There are collaborative grants, but usually only for PIs (as far as I know). Its a tricky issue. As PhD/PD, even if your TEAM succeeds, Universities/Inst. hire Individuals. I think the PD pressure (that can lead to egoism) mainly comes from limited academic jobs. Agree?
Hello Friends! In this 🧵I will tell you about my favorite topic: NOISE 😁 Richard Feyman once said: "There's plenty of room at the bottom". So here we are, nano-enthusiasts 😀 Now that the room is shrinking, I hope to convince you that "There's plenty of Energy in Noise" 😉 https://t.co/dxJLEM2npu
Remember: We have an energy crisis, not a size crisis. So KUDOS to all those who make increasingly smaller technologies. We love them! But the REAL challenge is to make all those nano-technologies ENERGY efficient. And for that, we need to take into account NOISE! https://t.co/fCeFw8Q5FE
Let me first tell you how I got into this topic. As a postdoc, I was studying a new type of dissipative phase transition of open quantum systems. 👇 Noise played a prominent role in those experiments, so I started to dig more into 'stochastic systems' https://t.co/AvBuWovAvB
During my literature search, and also hearing 1 colleague (who is now retired) in the field of polaritons, I came across the term "STOCHASTIC RESONANCE". This is a phenomenon wherein a certain amount of noise (in a nonlinear system) AMPLIFIES a periodic signal. I was 👇 https://t.co/06dVOdt5Qu
STOCHASTIC RESONANCE was introduced as a plausible explanation for the recurrence of ice ages in our planet. https://t.co/45H3RADhEm Did you know our planet goes into an ice age every 10^5 years or so? It was really difficult to explain this time scale. But SR *could* do it. https://t.co/KfSKFYXAgQ
There are actually much 'faster' variations in our planet's temperature too. See e.g. the figure👇, taken from https://t.co/u1TZToDCYX Every time I see this plot, I realize: a)We're so lucky to live in a warm (unstable) RARE EVENT b)Our planet's T is so fragile to perturbations! https://t.co/hzsjMQ8EDE
We literally owe life in this planet, as we know it, to noise. So how does that work? I'll try to explain the mechanism of Stochastic Resonance in the next few tweets👇 https://t.co/08daYYuSCv
First: Huge Thanks to @KJH_Peters for the GIFs! Imagine you have a Brownian particle in a double well potential (DWP), like this 👇 The particle's position fluctuates, due to (thermal) noise. Meanwhile, the DWP is modulated at period T. For weak noise, the part stays in 1 well. https://t.co/xJWV1eIqQl
If the noise strength increases a little, the particle can now make *random* jumps between the potential wells, like this👇 https://t.co/SkRW0ZSjEl
If the noise is VERY strong, the particle now makes LOTS of random jumps between the potential wells. Notice there are many (>>2) jumps per modulation period. https://t.co/rlXN8u58C9
But if the noise strength is right --- not too weak, not too strong ---, the random jumps of the Brownian particle can synchronize with the modulation. 👇 This occurs when the mod. period T is ~twice the avg escape time of the particle from a well. THIS IS STOCHASTIC RESONANCE. https://t.co/AgFvJCapNN
This simple model - Brownian particle in a double well potential - allows us to understand SO much. You'd be surprise to discover how many different systems, dead & alive, can be understood in this way. And so many display STOCHASTIC RESONANCE! Some examples below👇
Stochastic Resonance, i.e. noise-assisted amplification of a periodic signal in a nonlinear system, has been observed in: electronics: https://t.co/Dvs1qWvNR7 lasers: https://t.co/PnAjDUhZ3j superconductors: https://t.co/iZ9C5K3y7w Carbon nanotubes: https://t.co/bOq77HmtNH
Stochastic resonance has also been observed in a: polariton gas: https://t.co/kRVDwKr0WM cantilever: https://t.co/x8rb0oL0tt optomechans: https://t.co/QiIWv9mSVI levitated nanoparticle: https://t.co/VymsMxs0CO
Further, Stochastic Resonance has been observed in a: nano electromechanical membrane: https://t.co/V8d7VK1PQU in #quantum systems: https://t.co/OiewwH8Rrq and in chemical reactions: https://t.co/tAiLnkTYZr
But all those systems are 'constructed' by people. To me, the most amazing examples of Stochastic Resonance are found in living organisms. There are really MANY noise-loving organisms (like me 😊). I'll share a few examples 👇
This guy👇 uses noise to enhance information transfer to his mechanireceptors 😮 https://t.co/fgnuKcz6Lr https://t.co/wgmFYKmUIH
This paddlefish👇 (fig from wikipedia) lives in muddy watters & eats plankton. He can't see very well (tiny eyes). He uses electrical detectors in his big 'nose' (paddle) to detect plankton, and that detection range is enhanced by noise !😮 https://t.co/PVATlIgbns https://t.co/IIfzCLCzT6
There's also been a lot of work on stochastic resonance in the human brain. See for example: https://t.co/DllfqbkUVd Apparently, noise enhances our brain/perception 😮 https://t.co/5acdynwNlG
Even your tactile perception can be enhanced by noise: https://t.co/JsXWd3Vhp7 https://t.co/3w3YmyfhlJ
Also your visual perception can be enhanced by some noise 🤯 https://t.co/tEhI6zccOK https://t.co/U55tYPnTBH
And if you want to get rich in the market (or try to avoid loosing your money when it crashes), maybe its good to read a bit about stochastic resonance? https://t.co/4vDsUz3xA2 https://t.co/kl8lxIht4i
There are also many applications of stochastic resonance, like this one to imaging https://t.co/lOekcOvsVq
Seeing all this made me curious. How can stochastic resonance manifest in so many systems, when the phenomenon itself is so fragile? Remember we have to match the escape time to the modulation period, and the escape time depends EXPONENTIALLY on barrier heigth / noise strength
So we took a step back, and went to the beginning. Really, the beginning👇 Remember Newton's laws? Well, fundamentally, they're wrong. He argued that there are instantaneous forces. But NOTHING responds instantaneously! https://t.co/8ABnuWIHrH
Examples: When you pull a rope, someone at the other side doesnt feel your force instantaneously. The 'pull' has to travel via rope, and that takes time. Or if you dial up the heating (or cooling), that also takes time. https://t.co/wbMocTSs03
So we took at look at what happens to stochastic resonance when you let the NONLINEAR part of the force be non-instantaneous. We start from a so-called overdamped Langevin equation (x=position, F=force, \Xi =noise), and then we introduce a memory kernel for the nonlinearity. https://t.co/dDDJwm9kQk
The oil-filled optical cavity I mentioned yesterday is nicely explained by such a model. However, instead of position, we describe the light field in the cavity. The non-instataneous nonlinearity arises because the oil takes some time to warm up after the laser hits it 😉 https://t.co/UfXJsB0NCB
We then imprint a signal on the incident (continuous wave) laser by modulating the cavity length. Further, we add noise to the laser's amplitude and phase using modulators. So our experiment looked liked this 👇 https://t.co/ZH2JnMoJdR
We then measured the transmitted signal to noise ratio (SNR) as a function of the *input* noise. And found the peak characteristic of stochastic resonance. So our optical signal is amplified by a finite amoutn of noise. https://t.co/hCswN47Zcn
The cool part of the experiment (details here: https://t.co/uzVKP3VQHJ ) is that the frequency range over which we could observe stochastic resonance is enhanced, BY ORDERS OF MAGNITUDE, thanks to the non-instantaneous nonlinear response 😁
In that paper we also consider, theoretically, applications to energy harvesting. We find that the non-instantaneous nonlinearity can enhance the efficiency of those devices by a factor of 10 or more! 😮
Based on the success of our press release for the cavity with olive oil, we didnt want to let macadamia oil stay behind. So we wrote another one. And it got a lot of coverage by the media. We were very happy 😁 Below I'll share a few links to those 'reader's digest' articles 😉
Check out this nice & easy article in Optics & Photonics about our work: https://t.co/L2tY5F0HjX
or this one in https://t.co/NEEPm2rgDy https://t.co/sA3DusGzvz
or this one in Science Magazine: https://t.co/vq2rbB6ve1
I'll leave it at that on the topic of Stochatic Resonance. Please feel free to ask any questions you may have. I'd love to hear from you. I may tell a bit more about the wider 'benefits noise' next week. I wish you all a nice Friday and Wknd! End of 🧵
Hello friends! Besides working hard at the lab (or massaging your equations😉) , it's important to have some physical activity. It keeps us healthy, and happy 😁 I like to play tennis with my wife. We do that quite regularly actually. What do you like? https://t.co/y6GSr2UBFr
@sanarribas Great! Thanks for your comment. In that case, I will talk about superfluidity next week. It's a super amazing effect. In a nutshell: it allows light flow against an obstacle without scattering. I'll show nice movies & pics next week😉
@CredentialedRSS There's actually be many nice works on noise-assisted transport. And many believe (including myself) it may be the key effect behind the extraordinarily high energy transport efficiency of excitations in photosynthethic organisms. See for example: https://t.co/0tORebDsqA
@geuchies Thank you! Wow! you got the full thing going. I also love to do bike trips with my partner. Specially here in NL, they can be quite beautiful : )
@la_muscarella Thank you😊 ... Absolutely! I know you have your other half too, making another beautiful couple!
@Usman92Ali Thank you. You too!
@SvenAskes its close to AMOLF, in the UvA courts. you play too?
Hello friends! This wknd I'll share with you a little bit about the Netherlands 🇳🇱 and Amsterdam --- a beautiful place to live in. One of the things I love most is that you can cycle everywhere. Here 👇 I am at Veluwe National park. Pic from my wife. 😉 https://t.co/oDPwOVMOnR
Something I love of Amsterdam is that there are so many beautiful beautiful parks! Here is my group at Flevopark (a 5 min walk from AMOLF) making a BBQ 😋 I also like going there for walks with my group members. Its so much better to talk science in the park than in the office
Sorry, i missed the pic https://t.co/JWOD3niuE9
And here we were, a few weeks ago, enjoying a delicious vegetarian 😋 English breakfast next to one of the many lovely canals in Amsterdam. https://t.co/jiKhkxWK00
@SvenAskes Great!!! Good luck tomorrow! I hope you win 🤞and enjoy! Maybe we play 1 day?
Its a beautiful day in Amsterdam today. There are lots of people and boats going around, many celebrating our LGBTQ+ friends. Congratulations 🏳️🌈 friends! https://t.co/T8SadwUL1V
Hello friends! Today I'll share a bit about @_amolf (the research institute I work at) and how my group fits there. At AMOLF, we perform research on the physics of functional complex matter. You can find more details here 👇 🧵1/n https://t.co/tOE0R1wML8 https://t.co/d6h3V6ROye
The first thing to know about AMOLF is that it's a VERY dynamic institute. It's regularly changing! Example: More than 1/2 of current PIs have been here for <8 years. Do any of you know another institute or University that renews itself so much?
That being said, AMOLF is currently organized in the following 4 themes: At AMOLF we have 4 'Themes'. These are called: - Designer Matter -Nanophotonics - Nanophotovoltaics -Living Matter.
The AMOLF themes are very connected. Like this👇 There are lots of collaborations, and a strong community spirit. I think those are key factors which make an academic institution great. https://t.co/uRQlQBt9uU
@la_muscarella already gave you a very nice overview of AMOLF some weeks ago, when she curated this account. She works in the group of @brunoehrler, part of the Nanophotovoltaics theme. Their theme conceives & implements new ideas for sustainable energy, focusing on PV 😉 https://t.co/FxQSxkpoYq
In the NanoPV theme there R 3 more groups: - Nanoscale solar cells (@AmolfNsc), led by Erik Garnett - 3D PV (@3dPV_group), led by Esther Alarcon - Photonic Materials (@PolmanGroup), led by Albert Polman *Actually, Photonic Materials group is also in the Nanophotonic theme😉
In Nanophotonics we are 4 groups: - Resonant Nanophotonics, led by Femius Koenderink - Photonic Forces, led by Ewold Verhagen - Photonic Materials, led by @albert_polman - Interacting Photons, led by yours truly😊 Together with NanoPV, we make the Center for Nanophotonics https://t.co/oAXy35RxZG
We do all kinds of fun (and technologically relevant!) things with light! 👇 We trap it in volumes ~a million times smaller than its wavelength, guide it one-way only and without scattering, use it for signal transmission & computation, to drive chemistry, to illuminate, & more https://t.co/k7bTWRoodJ
Later this week, I'll be talking in more detail about specific projects in my group. Did you know that light can become a SUPERfluid? I'll show you what that means later. Meanwhile, is there anything you would like to know about AMOLF? end of 🧵
I forgot to mention something important: There are several exciting job oppotunities @_amolf see here: https://t.co/JDQDcnHO5c My group currently has no PhD/PD vacancies. But we are happy to host MSc students (EU nationality or enrolled in Dutch Uni only, unfortunately). https://t.co/SbV7U0yYqF
Every time politicians argue that we need to extract & consume more fossil fuels because renewable energies are not yet economically viable, I want to say: What is the economy good for if our habitat and nat. resources are destroyed? The economy is NOT the most important thing! https://t.co/yM4yXObXjR
Fun fact about AMOLF: Before corona, we organized many events to celebrate science! Ex: ~2 years ago, @albert_polman , @brunoehrler , and I organized a Nanophotonics summer school. We had fantastic boating + BBQ with all, and invited the lecturers for dinner cruise in Amst. 😉 https://t.co/SbV7U0yYqF https://t.co/StBpy42FXW
Hello friends! Today I share about the fascinating physics of fluids of light! 🧵 Did you know that light in a cavity behaves like a fluid? Top image is a boat cruising through a lake. Bottom image is our laser cruising through the cavity mirrors and scattering off a defect.😮 https://t.co/1iuEmNmVEH
Normally, when light encounters an obstacle it scatters. Then, incident & scatttered light interfere, resulting in fringes. See image above 👆 However, in 1999 Chiao et al. predicted that light may transition to a SUPERFLUID and flow without scattering! https://t.co/IfCKUNY4V5
However, to realize superfluid light, photons need to interact. And they normally dont. So, Iacopo Carusotto & @CristianoCiuti proposed leveraging the strong interactions of polaritons (1/2 light, 1/2 exciton quasiparticles) to realize superfluidity! https://t.co/5dAswzs3Xd
This is a figure copied from their article, cited 👆 On the left you see a polariton fluid scattering off a defect in the center. On the right you see a polariton superfluid, which doesnt scatter. To get there, they increased the laser power (fluid density). Amazing effect!😉 https://t.co/2VMig92Si8
Then, in 2009 came these beautiful experiments by Alberto Amo (one of my postdoc advisors) et al verifying the predictions of Ciuti & Carusotto. https://t.co/wveXhNNlU8 Left: 'Normal' polariton fluid, scattering off a defect. Right: Polariton SUPERfluid, flowing past the defect https://t.co/YvT6Q6BGLa
The results above gave birth to a new research field called "Quantum fluids of light". Results up to 2013 were reviewed in this nice & didactic Review of Modern Physics by Carusotto & Ciuti. Check it out if you're curious about the physics 😉 https://t.co/ro1Fi8nWan
The experiments of Amo et al used a sample at ~5K. It needed to be so cold for polaritons to exist and strongly interact. So several researchers began working on new platforms where superfluids of light can exist at room temperature. Major result 👇 https://t.co/vtWuCbMFJU
The above result (group of Daniele Sanvitto) is VERY nice. They showed, for the first time, a polariton superfluid at room temperature. However, since interactions in organics are so weak, they pumped the sample with a powerful amplified laser. And the fluid died within 0.1 ps😖
Inspired by all results above (+others), my group started an experiment aimed at observing superfluidity of light (photons, not polaritons) at room temperature AND in steady state. Imagine: A photon superfluid that lives forever😮 Our sample👇: A cavity filled with olive oil 😋 https://t.co/2q0el5692c
Together with Giel Keijsers (formerly MSc, now PhD student ) we got some nice results: https://t.co/ppmnaWyVeB Check out our preprint if you're curious about how a drop of olive oil between 2 mirror can suppress scattering of a light 😉
Here an movie of our data. Left: Real space, laser flows left-to-right to defect. Right: Momentum space. As time progresses, the photon fluid velocity increases. We start in the superfluid state, which later breaks down at high velocities -- fringes & backscattering appear. https://t.co/V2qpRRRXC8
Our manuscript shows many nice measurements. But, I admit, results are not as strong & conclusive as we would like. The referees, while most supporting publication, picked on that. So we've been doing new experiments for past months. We have amazing result in store for them😁
Unfortunately I cannot share them yet --- I dont want to compromise a future publication. But, if you like to know more later, follow me on my account, @srk_rodriguez , and I'll post the new results and movies when they ready😉
To end this 🧵, some great groups working on quantum fluids of light which are active on twitter (the ones I know): Experiments: Pavlos Lagoudakis, @lagoudakis_p Hamid Ohadi @FluidsOfLight Christian Schneider @SchneiderQMat Theory: Cristiano Ciuti @CristianoCiuti
@dbirch214 thank you 😊
@dbirch214 hum, physics for charged particles is very different. Electrons can also condense and flow without friction. But they do so in (Cooper) pairs, aka superconductivity.
Hello friends! After a week of fun science waves, a cold shower of reality. This 👇is what the life of a REAL, accomplished, scientist can look like. My exp is similar. I've got 2/14 grants since 2018. 1 of them is xtremely small (thats what it's called). A test of resilience? https://t.co/LFQFhpdAkM
[admin] "Benefits of Noise" Extended conversation with the amazing Said (@srk_rodriguez ) is out now 👇🥳🎧 https://t.co/6yIjLF30vB
@MannaLiberato Agree. But what then should the funding system reward? Do you agree that there is a distribution of ingenuity/talent among scientists? Or you think everyone is effectively "the same"?
Friends: my "cold shower of reality" isn't meant to demotivate anyone to continue in science. It's just a 'heads up' that, if you make it to the other (PI) side', you may have to endure a lot of rejection. And it's painful. You may want to know it, and start growing a skin😉 https://t.co/5QGENNjMpZ
@MannaLiberato @RattoFulvio I think we all recognize what the problem is. And we agree. But we seem to be stuck because we cant agree on how to move beyond the vicious cycle. Many seem to forget the badness of the system as soon as they win a grant in it.
Hello friends! Today I share some things that have helped me in my scientific path. 1. Regardless of your specialization, you need to EXPLAIN things. But what IS a good the explanation? This 👇 is the best explanation of explanation I've heard 😉 https://t.co/P7Pc1014Ay
@RattoFulvio @MannaLiberato So please 🙏 voice your criticism and ideas for changing the system ESPECIALLY stronger when you succeed in getting a grant in the current system. That is a much more powerful statement. Otherwise, our statements are perceived as "sour grapes". I know some of mine are.
Ups. Seems something went wrong on the link. Here it is. https://t.co/RmIWhbVpRt
@V_Saggiomo @MannaLiberato @RattoFulvio THAT discussion is much broader. And we can get into it if you like. The statement of Fulvio is that giving 99% of the money to 1% of the labs is inefficient. Do you know anyone, even 1 person, that seriously thinks that's an efficient approach? I'd like to know who & why
@V_Saggiomo @MannaLiberato @RattoFulvio @deVSNU There R 2 things, related but not same. 1. Everyone agrees a *huge* inequality hurts science. 2. There R different views on HOW available funding is distributed. On 2, 1st question fueling debate: Is there some performance metric (which?) we should use, or just lottery?
@V_Saggiomo @MannaLiberato @RattoFulvio @deVSNU Its not that simple. Myself as example. I got FOM Theis prize, C Huygens hon mention, Marie Curie, Veni, KNAW EC award, ERC StG, (Mathew effect?), and then no Vidi bcs I "need to talk more with my peers". I gave tech answers to tech questions... And I want to change the system!
@V_Saggiomo @ChirpDontTweet @MannaLiberato @RattoFulvio @deVSNU A blunder
@RattoFulvio @MannaLiberato I think it needs to be a combined effort. We should fight so that the fate of science is not in the hands of people who have, most likely, never done science. Our part is to show them the benefits of a more inclusive & equitable science environment.
1 question friends: When, why, & how was it 'institutionalized' that the PI supervising the work is the *last* author? I hope the ones who did it werent misinterpreting Jesus: "The last shall be first and the first last". In science, 1st R 1st! And I hope the last R not last🤷🏽♂️
@MaterialsDan Interesting. I didnt see the 'disguise self references' coming. You really think thats a main thing behind it?
@MaterialsDan Sure, it's convention. Still, My question is: when, how, why, that convention started?
After reading about the fires that ravaged Greece, I saw this article 👇 Seems like politicians & policy makers still do NOT understand the urgency of the transition to renewable energy. Did the IPCC report landed nowhere? What will it take? 🙏 https://t.co/Hm77S3jnhp
PhD students showing their poster to a known member of the jury for the "best poster prize"? https://t.co/WVIypYtoIN
Hello friends! Before leaving this account, I'd like to share valuable insights & experiences I gained as PhD #student, #postdoc, and #newPI. These are on various aspects of science. My insights are obviously not universal. Please take them with a 'big grain of salt'. Open 🧵
#1. NEVER EVER write an email when overwhelmed by emotion. This is especially relevant when the emotion is anger, regardless of whether it is justified or not. When receiving bad / unpleasant news, it's best to let it rest AT LEAST 1-2 days before responding.
#2. In myself and in my scientific team members, I welcome every feeling/state (expressed with respect) EXCEPT BOREDOM. A person that is bored has lost curiousity, and awareness of how little she/he knows of this AMAZING universe. There is always something great to learn!
#3 A. When searching for PhD/PD position, many these days recommend setting "emotional support" as no. 1 in search criteria. I never did that. For em. supp. I have my wife, my parents, close friends, and coach. Of course, em. support from PI is very important, but not enough.
In a #PI, I searched for someone with: 1. Inspiration & Creativity 2. Scientific & Personal Qualities which I lack, and ability to teach them 3. Resources 4. Ability to guide with enthusiasm 5. Local environment where I can thrive 6. Strong Internatl Network 7 Easy to talk with
#4. You can learn what you need along the way. Ex: As young student, I thought I should the be able to solve all (or nearly all) problems in Jackson (hard book!) before doing any research in E&M / Optics. I was wrong. Solid foundation is good, but adaptability also. .
#5. A highly DANGEROUS time (physically) for an academic is during PhD thesis writing. I foolishly thought "I will not stand until I finish writing this section". So I spent too many hours sitting. I injured my back badly (sciattica) and suffered for years after. Health FIRST!
#6. Between my PhD and PD, I published my 1st single-author paper. I highly recommend that. It's a good way to demonstrate independence, as well as ability to conceive, implement, and finalize a scientific project. It can also prove good writing skills --- essential in academia.
#7. Every paper that I wrote eventually got published. Sometimes many things had to change, and once the revision process took 3 years. But eventually it was published. So I've learned not to sweat paper rejections. I know the outcome 😉 (Grants are different 😖).
#8. As #newPI in experimental group, I've learned to ask my students if they would like me to join them in their experiment. Some students feel pressured by my presence. Others feel supported. So I just ask , and I'm happy to join when my presence helps. And not sad otherwise.
#9. When responding to referees, remember: their (our) only reward is the satisfaction of helping a good paper become better (rejected papers appear elsewhere later). So I listen to referees & follow their advice as much as possible. It's better than to fight them all the time😉
#10. When a Referee is unreasonable/absurd (rare, but can happen), remember: we do NOT have to convince Referees. The Editor decides. That's why I rather publish in journals where Editorial decisions can be assessed by members of the science community via appeals, if necessary.
#11. Time is our most valuable resource. Many people ask: Is this an idea worth researching, or a paper worth writing? That's a bad question - can lead to time waste. I rather ask: Is this the *best* idea worth researching, or best paper worth writing, given our possibilities?
#12. More experiments/data alone rarely lead to deeper understanding. Actually, they often strengthen the confusion. Understanding emerges from our ability to reproduce and predict partial observations using a "simple" model/abstraction of reality.
#13. For me, the best experiments (worth doing) are those for which I don't know the result in advance, can surprise me, or are beyond theoretical reach. Otherwise, if the theory has been tested to death, and we know it faithfully models our system, why do the experiment?
#14. I've seen many students choose to work on a topic because of its *potential* relevance to an issue they care about, e.g. health, sustainability. But many soon realize that they do not enjoy their daily activities so much. Daily inspiration is AS IMPORTANT as purpose.
#15. A great challenge as a PI: When someone systematically doesn't honor IMPORTANT agreements (they may think it's not important), how to express that behavior is unacceptable WITHOUT diminishing their motivation? Nobody likes to be reminded of agreements they didnt fulfill.
#16. In personal relations with fellow scientists, I appreciate modesty and detest self-adulation (e.g. bombastic claims that their research will save the world). Unfortunately, that doesnt work well in proposals. Non-specialists easily fall for nicely-written bombastic claims.
@n_maccaferri Thank you Nicolo!
@nur_ayukaryana Important decision! Did you see my point #3 (2 tweets)? Other factors I considered: 1. Quality of life (for me: salary, living, transport, access to nature) 2. Before accepting PhD offer, I asked my adivsor for support to visit theory group for few months. 3. Technical support!
#17 In France, I learned that a scientific group's leader is called "animateur". Funny, I thought. But there is so much wisdom in that name. Truly, the greatest aspiration of a group leader is to amplify the motivation of her/his group members.
#18. The most important & difficult decision of a #newPI is in hiring. Unfortunately, this is likely also the decision we are least prepared to make. IMO, character is the most important quality to look for. Its easier to teach exp skills than to change character.
#19 As PhD & young PD, I thought that increasing my skill set was the best way to land in a tenure-track position. I was wrong. Hiring committees rarely look at skills. Most look for innovative ideas (of the type that can bring millions), ability to lead, & a friendly colleague.
#20. In my PD, when starting to search for tt position, I didnt have a research statement ready. I thought I would make one when I apply. Then, a senior colleague I admire said: "If you dont have your proposal always ready, you'll never get a position." He was right.
#21. As PhD student, I improved my presentation skills thanks to detailed (written) feedback I got right after each talk. This is standard practice at nanophotonics at AMOLF. For years, I've seen the big difference that giving this feedback makes in the quality of student talks.
#22. The classic mistake of an enthusiastic PhD student (I was one) is to start more research projects than s/he can finish, i.e. lead to publication. IMO, there's no point in starting projects one cant finish. In long run, only the projects one finishes (publishes) matter.
@nur_ayukaryana Sure. I like doing experiment & theory. My MSc supervisor (offered me PhD) was very strong experimentally, but not so much theoretically. So, when I expressed my concern (wanted to also do theory), he offered me a few-month paid visit to top theory group in Spain, which I did🙂
Hello friends! It's time for me to say good bye. It was a great experience for me to curate this account. Thank you for all our interactions! If you like to read more about light, oil, noise, and the perks of being an academic/ physicist, follow me at @srk_rodriguez . 🙂 https://t.co/3iLeIoA23S
[admin] Huge thank you to Said for very insightful, fun and amazing 1.5 week. Do give @srk_rodriguez a follow! Podcasts ft Said where he speaks about his science 👇🎙️🎧 Short - https://t.co/AkPOXeT8Xf Long - https://t.co/6yIjLF30vB https://t.co/LQDTPvErHx
Yolanda Manzanares
[admin] "Punching Materials Until They Get Angry" Please welcome @yolicomoelrio and listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/ZYsK7cs8Xv
Hello everyone! My name is Yolanda Manzanares (@yolicomoelrio ) and I'll be curating this account for the next week https://t.co/V272ZNUhKh
This week I'll talk about different things:
TODAY: brief presentation. Something about me and the lab I'm doing my PhD in.
TOMORROW: 2D materials. Exfoliation and transfer: painful or relaxing?
WEDNESDAY: SPM. Techniques I've learned to perform so far (mostly AFM)
THURSDAY: other uses of AFM. What do other groups do?
FRIDAY: the lab in summer. Wanna cry with me?
WEEKEND: curiosities from Madrid
I'm a PhD student at Universidad Autonoma de Madrid. I study 2D materials with an AFM, and today I'll try to do my best telling you how I got here and what people in the lab were doing before I arrived.
I finished my physics degree in 2016. My final project was , first of all, taking images from a graphite sample with atomic resolution. When I made it (💪💪💪) I started taking images of moires created by rotated samples. This year I fell in love with scanning probe microscopy! https://t.co/suqLAX42su
After that I enrolled in a condensed matter physics master, and met the group I'm working with right now (I guess I did a good job during the master...)
@ulrich_hofmann That's a moire. The superposition of two (or more) 2D lattices create a bigger lattice. This new lattice depends on the different rotation group of the two base lattices, the relative angle between them and the different periodicity. In this case the only change was the angle.
In this group, people not only uses the SPM systems to measure, but also build their own systems!! If you were following this account some weeks ago, you may have met @pablerasares , who told a bit about their history (he was there before me and explained it very good)
I've been here, focused on AFM, most of the time, but for the beginning of 2020. I went to Texas for a short stay with a group on optics, but we all remember what happened in March... so easy to guess how it finished 😌
After telling you my super short career in science and things I've learnt, I want to show you something I'm supposed to know but truly scares me... https://t.co/vbMYewyFVs
Is there anything you are supposed to do, but find scary?
@Alireza10779829 Hey! Yes, Pablo is great. When I arrived at the lab, he was finishing/just finished his PhD. My advisors here are Julio Gomez and Cristina Gomez-Navarro.
Todayyy a short thread about our favorite issue in the lab! Exfoliation!!! 😍
As you probably know, exfoliation is a technique to obtain very thin samples of layered materials. And it's very extended! So, if you are familiar with the technique, do not hesitate and tell us your experience :) (luckily I'll complete the thread with some pics tomorrow)
First of all, you need a small (but macroscopic) piece of the material that you want to use. And put some of it in a scotch tape. Then, you peel it with the tape, and if you are lucky, there will be some very thin and large layers of whatever you are exfoliating...
Directly pressing the substrate where you want to build the sample against the tape. Then, look in the optical microscope and search if there is any layer adhered to your substrate.
There may be many, but if you are interested in a specific thickness and area, finding a good one usually takes many tries and a lot of time...
I think that the second most common technique is, first, pressing a layer of a viscoelastic material (such as PDMS) and then transferring it to the exact place where you want your flake to be.
If you put everything in contact, and then tear the viscoelastic very slow and gently, the flake will remain where you put it in the substrate. Some groups use commercial PDMS, others make their own... what do you think is better?
Also this transferring technique allows making heterostructures of many layers, as you know exactly where the new flake will be in the substrate. You can even create rotated samples!!!
But I forgot to talk about the most important thing when preparing samples 😱 which material do you want? 😱
The only thing you need to know before starting to exfoliate, is if your material can be layered. The difficulty will vary depending on the interaction between the layers, so you need a lot of patience. Also optical contrast will change depending on the material and thickness.
This is something that a lot of people do, specially at the beginning of our journey in 2D materials, and can be a bit boring and/or stressful, so I'd recommend that you exercise your eyes and let them rest while listening some good song! Can you recommend any?
[admin] "Punching Materials Until They Get Angry" Extended conversation with the amazing Yolanda - @yolicomoelrio - is out now 👇🎙️🎧 https://t.co/J0l35HMPsw
Good morning! Today's and tomorrow's thead(s) will be about AFM and its possibilities. Today: I'll tell you the two basic modes to take topography images, and some other techniques I've used so far. Tomorrow: techniques I haven't used but are super interesting and useful.
In simple words, an AFM consists of a very thin tip at the end of a cantilever that you can move around a sample with very high precision. Depending on your system, is the tip or the sample what moves! You measure the deflection of the cantilever by reflecting a laser on it.
By doing this, you can measure the force between the sample and the tip, as the cantilever will bend depending on it. If you put the tip in contact with a surface and sweep it keeping the force constant, you can actually have an image of its shape!
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Something you can do when mapping the topography of the sample is applying a constant voltage. If the tip is conductive, it allows mapping electrical properties of your sample 😏 (current maps)
If the applied voltage oscillates, then you can even map the piezorresponse of the material 😱 (piezorresponse force microscopy)
It is also possible to follow the topography in dynamic mode. In this case, the tip is in constant oscillation, and what remains constant is the amplitude and phase of the oscillation when it interacts with the sample at short distances (5-20 nm)
This other method is less invasive as you are never applying force in the sample, so it is useful for soft materials, for example.
Going one step further, you can also apply an oscillating voltage to the tip 😱 two oscillations at the same time 😱 that's Kelvin Probe Microscopy (KPM). Following the phase of this second oscillation it is possible to map the electrostatic potential of metallic samples ❤
Other uses of AFM are possible when combining dynamic and contact modes 😀
Indentations: with the dynamic mode you can locate the tip in a specific point of the surface. Then, in this point, you can apply a force and/or a voltage leaving the rest of the sample untouched.
SPANC! Scanning probe assisted nano-circuitry. Several nanowires and particles on a surface can become a circuit with some help of an AFM tip. If they are not very attached to the surface, the tip can move them with a touch, and map the resulting circuit without touching :)
RT @realscientists: #AcademicTwitter - I’d love to hear your #ImAScientistAnd stories away from #PhDLife and #Science (3/3
Finally the weekend! What plans do you have? How was your week? Mine was very busy, and weather was so hot (and dry) here in Madrid. Do you have any tips for going to the lab in this weather?
My three little tips are... - wearing my hair super secured in braids or ponytail (that's good for safety even in winter) - comfy cotton clothes - espadrilles. In four dry summers in the lab, I never had a crump wearing them. https://t.co/MARBkifo3R
RT @realscientists: Good morning everyone! It's great to be running the account this week. Today I'll be tweeting from Manchester & Sheffi…
The week is ending so it's time to say goodbye! I wish you enjoyed reading about the basics of exfoliation and AFM ❤
[admin] Huge thank you to Yolanda for a wonderful week of science, do give @yolicomoelrio a follow. Podcasts where Yolanda speaks candidly speaks about her science are here 👇🎙️🎧 Short - https://t.co/ZYsK7cs8Xv Long - https://t.co/J0l35HMPsw https://t.co/Rx8rG6qMQQ
Karyn Jarvis
[admin] "Magic of Plasma & Thin Films" Please welcome @dr_karynJ on @RealSci_Nano 🥳 Listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/Bm9QigYwDX
Hi everyone! I'm Karyn Jarvis @dr_karynJ , tweeting this week from Melbourne, Australia! I'm a senior research engineer at @Swinburne, working in plasma polymerisation and surface characterisation! Keen to take you all for a fun ride!
Today, I'm going to be going to be detailing my scientific career and how I got to where I am today!
I was never one of those kids with a chemistry set, I wanted to do a whole lot of other jobs, like a hairdresser, physiotherapist or a teacher! When I was in high school, I got good grades in most in most subjects, so didn't really know what I wanted to do!
I like maths and geography. But couldn't really see how I'd turn them in a career. I like chemistry, so I thought, why not go to university to study chemistry? I found a chemistry degree at @UniversitySA and started in 2002 (I'm so old!)
Just a bit of background about me! I grew up on a sheep and wheat farm in an area of South Australia known as the mid-north, not far from the Barossa Valley (which I'm sure you've heard of!) https://t.co/6ZdRQGQ5yc
@sciencenotscary @UniversitySA There certainly doesn't seem to be as many of us chemists around!
So, I loved my chemistry degree at @UniversitySA, especially as in 2nd and 3rd years, I had 4 chemistry subjects each semester (Inorganic, organic, physical, industrial, analytical, environmental etc.), and I got to spend every afternoon in the lab!
Coming to the end of my 3 year degree, I didn't really know what I wanted to do (a reoccurring theme in my life!), so I decided to do a 1 year honours program and get my first real go at a research project!
That was 2005, and its when I started looking at surface modification. I investigated depositing inorganic coatings on carbon cloths for the degradation of chemical warfare simulants!
In my honours year, I saw an interesting talk from @ClivePrestidge, and chatted with him about a PhD project! I started my PhD in 2006, investigating the modification of porous silicon for drug delivery!
My #1 recommendation for young people in science: Summer projects! I spent between 2nd/3rd year working in a QC lab at a cement factory. Didn't love it, but I learnt that!
Between 3rd year and honours, I did a water quality research project. Taught me that I liked having my own research project, and that to work in research, I'd probably need a PhD. It was probably the biggest influence in me choosing to do a PhD!
So, I had a great time doing my PhD at @UniversitySA at the now unfortunately defunct Ian Wark Research Institute. I worked alongside a bunch of great scientists, such as @dabeattie99, @BillSkinnerAu, @marta_krasowska, @Engineeringkate!
I also learnt about a tonne of surface modification techniques, such as FTIR, AFM, XPS, ToF-SIMS and Zeta potential!
I also got to visit a lot of interesting places for experiments and conferences, like the Taiwan Synchrotron, Spain and the UK! https://t.co/W4pIqic19m
That should be characterization, not modification!
@Dogar000786 @dr_karynJ You can! Fire away!
One of my favourite parts about being a scientist is all the travel I've been able to do, pre-COVID of course! I've visited some great places before/after work trips! Can you pick the city/place? https://t.co/6ZxQ8zqzYB
@Dogar000786 @dr_karynJ That's an excellent question. Honestly, no idea! I can't imagine thought it's going to be until 2022 though. Vaccine rollout in Australia has been pretty slow, and I can't see it opening before a high percentage of Australians are vaccinated!
Also throughout my career as a scientist, I've made some amazing fellow scientist friends, who now live across the world! Hoping to get back and visit some of them soon! https://t.co/dZIx7UGWP9
Gosh....it's home time (Well, I'm already home since WFH, but still) here in Australia and I'm still in my PhD! Still plenty of tweets to come today!
As I said, had a great time during my PhD learning about surface modification and characterisation. I submitted my thesis id 2009 and graduated in 2010! https://t.co/SbgokLkdnJ
2010 wasn't the best time to be looking for a postdoc (GFC and all). I really wanted to do a postdoc overseas, but things didn't go as planned. I stayed on at UniSA for a 3 year postdoc, which introduced me to plasma polymerisation, which I still work it today!
My first postdoc looked at modifying the surface of sand particles with plasma polymers to extract different water contaminants! Here's a video that we did for the Australian science show SCOPE! https://t.co/MfaHV91vhU
After 11 years at UniSA (3 as an undergraduate, 1 for honours, 4 fro PhD and 3 as a postdoc) I left UniSA and South Australia for my second postdoc at @ANSTO!
Make sure you tune in tomorrow, as I'll be introducing plasma polymerisation! What it is and what we do with it!
@SvenAskes Totally agree! I only spent 6 weeks in the cement factory lab, they wanted me to stay on, but I wanted a bit of a holiday before going back to uni!
In 2013 I moved from Adelaide to Sydney to start a 2 year postdoc at @ANSTO, Australia's federal nuclear science and technology organisation, which has Australia's one and only nuclear reactor! https://t.co/8PARiIDOZf
The OPAL reactor at ANSTO is a research reactor, and doens't create any power. If you'd like to learn more about the neutron facility at ANSTO, visit https://t.co/nvvc2S0oF0
My postdoc was part of the CRC for Polymers, which meant I got to work with awesome scientist from across Australia on polymer science projects!
Working as part of the CRC for polymers was great fun! My project was deposited inorganic barrier films to retard moisture permeation into organic solar cells! https://t.co/6Sqbw3fcqe
During this project, I used another thin film deposition technique, atomic layer deposition (ALD), which I'll also be introducing tomorrow! https://t.co/PBjyqEbC4m
But after 2 awesome years in Sydney, my postdoc came to an end! My partner had just gotten a job in Melbourne (after spending 3 years at the Italian synchrotron), so I decided to start looking for a job in Melbourne! https://t.co/3HZzLWbWKm
I already knew the fabulous @mca178 from @Swinburne, so I asked if she had anything going! Luckily, she had someone who was leaving, and thought I'd be perfect! So I moved to Melbourne for a 5 month contract, and that was 6 years ago!
My job at Swinburne is looking after the @ANFFHQ Biointerface Engineering Hub, where I look after a bunch of plasma polymer reactors and surface characterisation tools, train users and do my own research! https://t.co/k4F2Icyn9h
Now we're in the current day! Hope you've enjoyed the journey through my career today. Signing off, but I'll be back tomorrow to introduce you to thin films and plasma polymerisation!
Ready for Day 2? Today I'm going to be introducing you all to thin films and plasma polymerisation! So, to start with, what is a thin film?
To explain thin films, we first need to define what a surface is. This might seem obvious to some, but when we talk about a surface in science, we mean the outside layer of an object, usually the 'top' as a lot of the objects we work with are 2D, like silicon wafers! https://t.co/rtcybo5j49
A 'thin film' is a coating that we typically deposit onto a surface, usually nanometers (0.000000001 m) to micrometers (0.000001 m) thick! Typically we refer to these materials that we coat as substrates. https://t.co/uVS37ioIVK
@ChrisMillsRD @realscientists I'm #FirsGen too. I don't know what it's like in other countries, but my lecturers regularly told us all about summer job/project opportunities. I got my cement QC job through my own initiative, but I'm pretty sure the research project would have been widely advertised.
Now that we know what a thin film is? What type of thin films are there out there? And how do we deposit them?
Thin films can be organic (only containing O, C, N, H, S, P) or inorganic (Like Al2O3, ZnO, SiO2 etc.) Whether you need an organic or inorganic film depends on what you want your film to do! And type of film you want dictates what deposition methods you need!
Thin film deposition can range from quite crude, such as using a doctors blade, where you're simply spreading a paste onto your surface that then dries and forms the thin film! https://t.co/kg6YOM11qc
Or you can have very precise deposition, like atomic layer deposition (ALD) where you're actually growing ultra thin layers atomically on a surface! https://t.co/Wrdlm5edI4
I'm going to be focus on the more precise lab scale thin film deposition technqiues, which we typically separate into physical vapour deposition (PVD) or chemical vapour deposition (CVD).
So what's the difference between PVD and CVD?
Physical vapour deposition (PVD) typically has the substrate mounted opposite the source material which then physically deposit the source material on the substrate by heating/ablating/sputter of the source material https://t.co/8cZuDfmQRB
Some example of PVD are sputter coating, thermal evaporation, electron beam evaporation etc. https://t.co/VEoxrnFVHS
Now that I've covered PVD, it's time for CVD! In Chemical vapour deposition (CVD) the wafer surface is exposed to one or more precursors, which react and/or decompose onto the substrate surface to produce the desired thin film https://t.co/S38RmxASrH
Examples of CVD techniques aerosol assisted CVD, plasma enhanced CVD, hot/cold wall CVD, metal organic CVD etc. Plasma polymerisation is a type of CVD, that I'll be discussing in more detail later today! https://t.co/0ACpFgdf7Y
Atomic layer deposition (ALD) is a special type of CVD, where the film grows atomically. By keeping the deposition in the ALD rather than CVD regime, specific film properties, such retarding moisture/oxygen permeation, can be produced! https://t.co/lxsRiJFDzb
So what's the advantages and disadvantages of PVD and CVD? PVD: Typically deposits single single/simple materials but harder coatings, wide variety of film types available across a variety of techniques, but also require 'line of sight', so difficult to coat complex geometries
CVD: Typically produces more uniform coatings and onto more complex geometires, can be used to deposit coatings that do not have suitable PVD sources but often requires higher temperatures for the reactions to occur
Here's some useful figures that compare PVD, CVD and ALD! https://t.co/dOcRD5hn5v
Now that we've covered PVD and CVD broadly, now its time to introduce my thin film deposition technique of choice.....PLASMA POLYMERISATION!
But before we explain plasma polymerisation, lets familiarize everyone with plasma itself! Plasma is the 4th state of matter, and results from the excitation of a gas, which fragments the vapour molecules. This fragmentation is what produces the characteristic plasma glow! https://t.co/wqE72FaGGi
99.9 % of the universe is plasma, because most of space is comprised of plasma! Some examples of plasma here on Earth you might have seen are neon signs, lightning or the Aurora Borealis/Australis! https://t.co/5vIz9MkWeZ
Now that we're familiar with plasma, how do we use it to deposit thin films? Plasma polymerisation is actually the same as plasma enhanced CVD (PE-CVD), but is typically used to refer to the deposition of specifically organic thin films.
Our plasma polymerisation takes place in a vacuum reactor, where we suck out the air to reduce the pressure. A medium vacuum (10-3 to 10-2 mbar) is required for plasma polymerisation. We won't be able to ignite the plasma if the pressure is too high or too low! https://t.co/MMUW1mNX9z
We place our sample onto the sample stage.... https://t.co/fgiwTDSAex
And once the pressure is suitable, we can introduce our liquid monomer. This monomer either has the chemistry we want to add to our surface, or makes a film that has the properties that we're after! Introducing the monomer to the vacuum evaporates it into a vapour. https://t.co/VnuTqEDRTi
Once we have our vacuum chamber filled with the vapour, we can ignite our plasma! The monomer is fragmented, and produces the plasma glow! These fragments deposits on everything inside our chamber, including our sample! https://t.co/97Y5M1nvMZ
We call the films we deposit 'plasma polymers', although that's not true in a traditional sense, as they don't have the repeating sub-units of conventional polymers such as PET or PVC! https://t.co/GVIrmzoqmd
@SvenAskes No, but typically unsaturated molecules fragment to form more stable films due to their double bonds. Saturated monomers tend to fragment too much and deposit deposit as stable films, especially if you want to put them in solution!
Last tweets for today.....so what type of films can we deposit with plasma polymerisation? The films that we most commonly do are: -Allylamine: forms +ve amine terminated films -Acrylic acid: forms -ve carboxyl terminated films -Octadiene: forms carbon rich hydrophobic films
But, there's a whole lot of other monomers out there -Cineole: deposits films with antibacterial properties -NIPAM: deposits temperature responsive films -Allyl alcohol: deposits hydroxyl terminated films -Glyme (glycol ethers): deposit low fouling/protein adsorbing films
Signing off here for today! If you're interested in what sort of applications we use plasma polymers for, come back on Friday when I'll be exploring how we encounter thin films in our everyday lives!
Good morning everyone! Today I'm going to be tweeting about the organisation that I work for (@ANFFHQ - The Australian National Fabrication Facility) and discuss the benefits of open access user facilities!
The Australian National Fabrication Facility (ANFF) provides open access to micro and nanofabrication facilites for Australian researchers. The ANFF network is made up of over 500 instruments spread across 20 sites.
ANFF also has over 100 staff that can train users to independently use the ANFF instruments after training or have their work performed by ANFF staff under a fee-for-service agreement.
Since forming in 2007, ANFF has grown from 360 users and 38,000 user hours to 3000 users and 245,000 user hours in 2019/2020.
The instruments at ANFF are separated into the broad categories below, with some examples: - Deposition (ALD, CVD) - Etching (RIE/DRIE) - Lithography (EBL) - Packaging (Bonding and wafer dicing) - Testing and validation (XPS, profilometry, ellipsometry)
The ANFF @ANFFHQ network is composed of eight nodes, with their locations and specialties below! If you're interested in learning more about ANFF, check out their website: https://t.co/RfhlrODshS https://t.co/hBOW6s6aFb
ANFF is funded by the Australian federal government's National Collaborative Research Infrastructure Strategy (NCRIS) and supported by both State Governments and member institutions.
NCRIS provides a national network of world class infrastructure that facilitates research excellence and collaboration between 35,000 users from academia, government, and industry to drive greater innovation in the Australian research sector.
Apart from ANFF, there are a number of awesome Australian NCRIS facilites, such as: -@AuScope (Earth and Geospatial Science) -@micro_au (Microscopy Australia) -@NIFAus (National Imaging Facility) -@ARDC_AU (Australian Research Data Commons)
-@NCInews (National Computational Infrastructure) -@TERN_Aus (Terrestrial Ecosystem Research Network) -@phenomics (Phenomics Australia) - National Deuteration Facility (NDF) To name but a few!
Now lets talk about open access user facilities in general. I've listed some of the ones available in Australia, what about in your country? Have you used any of them?
Open access user facilities, for research typically mean you can use the facilities of another institution, usually for a fee. You can either get them to 'do' the work for you, or they can train you to do the work using their equipment.
So what are the advantages? I'm going to focus on those relevant for physical sciences, but there will be some overlap with other areas of research!
1. Expertise - You can utilize the knowledge and skill of staff to help you with an idea/process that you don't possess and may not have the time (i.e. during a PhD or an industry project) to develop 2. Access - You can access a tool quickly without purchasing or setting it up
3. Cost- Being able to access multi-million dollar equipment and processes that your organisation can't afford 4. Maintenance - Someone else's job to pay for and maintain costly equipment
5. Niche - Being able to access equipment that you might only need short term access to, so isn't worthwhile your group/university buying. Also may only be required by a small user base, so no point multiple institutions having one if its only used occasionally.
6. Optimisation - Accessing equipment to see if it works for a particular process before purchasing. Especially useful for industry! So, can you think of any other advantages of open access user facilities for research?
Well, it's knock of time here in Australia! Hope you've enjoyed hearing about @ANFFHQ, NCRIS and open access user facilities! Tomorrow, I'm going to give you a virtual tour of our ANFF-Vic Biointerface Engineering hub, the instruments that we have an what we do with them!
[admin] "Invisible Forces - the Magic of Plasma & Thin Films" Extended conversation with the amazing @dr_karynJ is out now 👇🎙️🎧 https://t.co/GwAGJUXfrj
@LunchBobs @RoyceInstitute @RoyceSheffield Yes! I used ANFF facilities before I started working for them. Not sure it helped me get the job, but it was good to already know people!
Day 4 people! Today I'm going to be tweeting about our facilities at the ANFF-VIC Biointerface Engineering hub at @Swinburne! Unfortunately, Melbourne is in lockdown so I won't actually be in the lab, but luckily I've got a good set of photos filed away for things like this!
Our @ANFFHQ lab at @Swinburne is a pretty standard looking wet chemistry lab but it houses a number of our thin film deposition and surface characterisation tools! https://t.co/AE4x3HrJAT
Lets start off with my favourite instruments, our plasma polymer reactors. I explained all about plasma polymerisation on Tuesday, but for a recap....
Plasma polymerisation is a plasma enhanced CVD technique that is used to deposit organic thin films. We have 6 reactors. 1 each for air plasma treatment (makes polymer surfaces more hydrophilic), allylamine (+ve amine), acrylic acid (-ve carboxyl) and octadience (hydrophobic) https://t.co/oxyh6GELRx
We also have two specality reactors: 1 heated, for the deposition of low volitile monomers such as NIPAM or Glyme and 1 for in-situ film deposition measurements with ellipsometry and IR. https://t.co/ehaiKoC03g
We usually do our deposition onto pieces of silicon wafer, but if it fits in the reactor, we can coat it, like these carbon fibers below! https://t.co/Ht2RZ9UJsh
Our reactors look like pretty standard vacuum reactors https://t.co/476qqsgYFn
But we do get to do some cool things with them... https://t.co/xkg44m8Hwt
And take some cool pictures of plasma! https://t.co/cfhHLd9wX5
What else have we got in our lab? My next favourite.....it's full name is a variable angle spectroscopic ellipsometer (VASE), but we just call it an ellipsometer! I've recently written an online learning module about ellipsometry, so I'll be stealing some of that info!
Ellipsometry is a quick, highly sensitive and non-destructive technique that is used to determine the thickness and optical properties of thin films from a few microns down to sub-nanometre. Here's our ellipsometer! https://t.co/rMZiIEULV8
Ellipsometry theory is complex, but put simply, a light at variable wavelength (200 - 1600 nm typically) is shone our sample, some is absorbed, some is reflected. The changes in the light that are reflected back to the detector, can be used to determine properties of the film. https://t.co/LhdNBy6l3o
In ellipsometry, the thickness and other properties of the film aren't measured directly. You need to create a model that generates a data set, and that data set is compared to the experimental data and is then used to calculate the various film properties
Here's an example of the data collected during ellipsometry. The red and the green lines are the parameters collected by ellipsometery (Psi and Delta) at the different wavelengths. https://t.co/4yHTRFZ8I3
Here's the process you go through to measure and fit ellipsometry data! https://t.co/UqGrOHADmc
To start the ellipsometry fitting process, you'll have your data (red and green lines) and model (black dotted line), and you'll need to change the parameters of your model for it to fit the data! Compare these unfit and fit data sets! https://t.co/RcY2HBaI3q
We typically use ellipsometry to measure film thickness, but it can also be used to investigate film: ▪Thickness ▪Surface roughness ▪Interfacial mixing ▪Composition ▪Crystallinity ▪Anisotropy ▪Uniformity
Apart from taking simple measurements, we can do a whole lot of cool things with ellipsometry!
By compiling single measurements across a silicon wafer, we can building mapping scans to tell us how uniform our coating is https://t.co/muXm2pJceg
We also have a variety of accessories that go on our ellipsometer: 1. Liquid cell - Investigate how film change upon exposure to different liquids i.e. vary pH or salt concentration 2.Temperature stage - Investigate how films change at elevated temperatures https://t.co/jiTycsvZzG
3. QCM module - Ellipsometry can be performed on a QCM crystal to do simultaneous QCM and ellipsometry measurements 4. Focus probes - Reduces spot size to look at very small features or films that are non-uniform over large size scales. https://t.co/JJAvivuSMO
5. In-situ - Components of the ellipsometer can be detached from the arms and attached to an appropriately outfitted deposition chamber to collect ellipsometry data during film deposition https://t.co/zfD7O5yogE
@ServicesVacuum @ANFFHQ @Swinburne That tricks a lot of people! It's not a multi chamber line, it's just the way they're sitting with the pump for one chamber sitting behind the adjacent chamber. These are plasma polymer reactors, essentially PE-CVD. These are for our allylamine, acrylic acid and octadiene.
Gosh.... not enough hours in the day to talk about all the instruments I want and get the reviewers comments done for our latest plasma polymerization paper!
Alas, got a few more instruments to talk about! A quick one is our multivessel dip coater! A dip coater is basically a robotic arm that holds a sample, and can then be program to dip into various solutions to build up a coating! https://t.co/Pcq9zRZGWk
Here's a great diagram from one of our previous users Daniela, on how she used our dip coater to deposit graphene oxide-gold nanorods https://t.co/5QsG3dawGO
Dipcoaters are really useful for solution based coatings, like layer-by-layer deposition, where you alternate positivly and negatively charged layers to build up the film! https://t.co/gowrCR9Lw9
@profechem @jona_a_foster Hi! Ours is a J.A. Woollam 2000 XI VASE. Our lamp does down to 210 nm, so could do from 210 to 250 nm. I haven't looked at the data specifically at that wavelength, so not sure how 'well' it works at that range!
@ServicesVacuum @ANFFHQ @Swinburne Secondary effects? Not sure what you mean.
Okay, last instrument! Now we're up to our Quartz Crystal Microbalance with Dissipation (QCM-D). QCMs have been used for a long time in thin film deposition equipment.
In QCM-D, we start with a quartz crystal that vibrates at a particular frequency. If there's any addition or subtraction of mass, that changes the frequency, which the instrument can use to determine the change in mass.
The dissipation part comes in as if there are conformational changes in the mass adsorbed, then that alters how long the crystal vibration takes to stop. This can be summarised in the below diagram. https://t.co/YhsvZrAqts
This is our QCM-D instrument. Off to the left, we'll have the solution we're exposing our crystal to. This solution travels through the tubing, and into the four grey cells which contain the crystals, also shown. The pump to the right pulls the solution through. https://t.co/DvyYET2eTG
Here's an example of QCM data. The frequency of the crystal decreases as mass is adsorbed. This work shows how negatively charged lipids are attracted to our positively charged plasma polymerized allylamine surface! If you're interested, https://t.co/wlGyuSCy3k https://t.co/bIUPiajdED
@ServicesVacuum @ANFFHQ @Swinburne Yes, we have cold traps between our chambers and the pump to try and condense as much of the monomer as we can. But we do get oil contamination, and have to change the pump oil more frequently, depending on how much the instruments are used.
Last tweet for today! As I've been talking about the instruments at our @ANFFHQ facility, I should highlight some of the research it has facilitated! @moraes_saimon and his students are doing some awesome work with our QCM-D with lubricin! https://t.co/zhn0QWUBJl
Our @deakin users have investigated improving the adhesion of plasma polymerized acrylic acid coatings on carbon fibers https://t.co/QFqhB0xV8h
Several @Swinburne PhD students have demonstrated some really interesting applications for our plasma polymer films. Like creating antibacterial surfaces: https://t.co/Gmd44JDnor https://t.co/qg38Oleb79
Depositing nanopatterned plasma polymer films: https://t.co/hcCTGndctJ https://t.co/j2lSpFNgSn
Plasma treatment of carbon fibers: https://t.co/0DfWyXLiDq https://t.co/Q4OVhHfZI2
Plasma polymer coatings of electrospun fibers: https://t.co/V1cynZKgPW https://t.co/eammyGDQD2
@ServicesVacuum @ANFFHQ @Swinburne Thanks. Will do!
Okay, this today's last tweet! Stayed tuned for the last day of scientific tweets tomorrow. I'm going to be some tweeting over the weekend to show you that scientists have a life too! Tomorrow I'll be tweeting about some of the awesome applications of thin films! Sneak peak..... https://t.co/oFTZGAELDm
@BreakingTaps Excellent question! A competitive ablation and polymerization (CAP) process occurs during plasma polymerization. So if the power is too high, a film won't be deposited as ablation will be dominant. So we have to keep it in the polymerization regime to deposit a film!
It's Friday! I think I'm most excited about the content I have for you today, because you'll be able to see how the stuff I've talked about all week is actually all around us!
Today, I'm going to be tweet about what surface properties we can modify withthin film coatings and then what applications thin films are used for. I'm going to be talking in general about thin films, so hard/soft, organic/inorganic, so not all films will do all of these things!
What surface properties can we modify with thin films? This list is not exhaustive. I'll discuss each one in more detail later. -Charge -Wettability -Reflectivity -Biocompatibility/Cell growth -Conductivity -Bacterial growth -Biofouling -Hardness -Colour Any others?
Lets start with colour, because its a fun one. No real scientific use here, but there's a lot of thin films that are used just for decorative purposes. You may have seen these cool rainbow coloured objects! https://t.co/scLcsj8KCN
In the lab, these rainbow coatings mean we have a non-uniform film, because colour gives us information about film thickness. But what is the relationship between colour and film thickness? https://t.co/c9bvQ47eSU
To start with, we need to actually explain what 'colour' is. If you have a red shirt, it appears red because it's reflecting the 'red' wavelength, back to you. All light has a wavelength, which determines if we can see it or not and if we can, what colour is it? https://t.co/Hnah7GvUlA
So, the colour of a thin film is determined by what colour/wavelength light it is reflecting. This changes depending on how thick the film is, as shown in these images! https://t.co/I5XaYiAnEA
Next up is wettability. If a surface is hydrophilic (water loving) then a water droplet will spread. If a surface is hydrophobic (water hating) then a water droplet will bead! Below are some examples of how wettability influences surfaces! https://t.co/uBWvpW6lP7
Generally, you can make a surface more wettable by adding oxygen groups to the surface or make it less wettable by adding F or C groups. https://t.co/AwwTG9FUsG
Both hydrophilic and hydrophobic coatings are required for different applications! 'Self cleaning' windows can be made using a hydrophilic coating, where the water runs off the surface. Hydrophobic particles can be used to remove oil contaminants from water! https://t.co/dGeQ8jI0cY
Surfaces can also be made 'super hydrophobic' by making the surface rough, but this usually needs another technique to roughen up the surface in addition to just thin films! https://t.co/Uzf5sSkgL4
Next up is reflectivity. Anyone who's got glasses might have been sold 'anti-reflective coatings' when they bought their glasses. Often this appears as a green tinge on the surface. That's the thin film!
Anti-reflective coatings work by increasing the transmission of light and decreasing the reflection of light through the glass, so that they appear clearer! https://t.co/if6zPR7sYk
https://t.co/LMdVifu1ws
We might want a certain surface charge so we can build up a film, layer by layer! https://t.co/Gg3DPHLC4q
Or we might want to attract something out of solution, to remove it! In this photo below, I removed humic acid (-ve charged water contaminant) using a positively charge plasma polymer to produce clear water! https://t.co/YAHI6bCdmn
Making surface conductive is super important these days, given all the devices we have in our bags/pockets/houses! We also need conductive films for solar cells! There are a number of thin films that can be used to create conductive surfaces! https://t.co/nemKgJ1c2w
Creating hard surfaces is also really important, especially for a number of engineering applications. These are typically metal/metal oxide films. No body wants a drill bit that keeps breaking! https://t.co/5RNMOF0k5h
Now we've just got biological surfaces to talk about. When we're talking about surfaces for biofouling, biocompatiblity, cell or bacteria growth, it's really the sample principle. What is it that we want to attract and/or repel!
In marine biofouling, you want to put a thin film down that repels the ocean critter than gum up the bottom of a boat! https://t.co/3hp7JQvD8M
If we've got an implant we want to put in the body, like for a tooth or a hip, we want it integrate into the bone, so it doesn't become loose. In this case, we'd put a thin film on that promotes bone integration! https://t.co/ds9WpUsdNy
We might also want to put an implant into the body that repels bacteria growth, or something like a door handle that can also prevent bacterial growth! There's thin films that can do that too! https://t.co/vc3PiumdW8
So, that brings an end to my week of scientific tweeting. It's 5pm here in Australia, and it's time for a beer! I hope you've enjoyed my tweeting this week and you've learnt facts about me, plasma, surface characterization and deposition tools, thin films and how they're used! https://t.co/DCpzmYV1Qx
This won't be the last time you'll hear from me though! I'll be doing some tweeting over the weekend to show you how a scientist keeps themselves entertained over the weekend in locked down Melbourne (Don't expect anything too exciting!)
Plus I'l also be back late on Sunday to sign off with some words of wisdom! Have an awesome weekend people!
https://t.co/tTZYQq9unx
@ColinJamesHALL That's true! I'm being rather disparaging of colour. It does have some uses other than just pretty!
Happy weekend everyone! Nothing exciting going on for me in locked down Melbourne today, but I did make an awesome cheese, procuitto and onion relish toastie for lunch! https://t.co/zuM4QouTdO
But the weather is nice today, so going to read outside for a bit! https://t.co/lhRie8Vbmz
Am enjoying growing some herbs from seed, as it's nearly Spring! I've planted basil, mint, coriander, dill, chives, thyme and sage! https://t.co/eFZhftjTbC
Got outside in the sun for a walk. Basically wearing a disguise! Moved house earlier this year, so nice to have a new area to explore. I'm always spotting new things! https://t.co/lltnGG3qDk
Also managed to fit in a home workout today, since the gyms are closed in lock down! https://t.co/QzNLeaWEp5
Usually do some baking on the weekend. Trying cinammon buns for the first time. Goes in the fridge overnight, I'll let you know how they go tomorrow! https://t.co/HjBp19Pfbh
Pretty happy with how my cinammon buns turned out. Love me some weekend baking! https://t.co/Zj4DDJMF9T
So, it's Sunday afternoon of my last day of tweeting. I'm going to follow the lead from last week, and finish off with my words of wisdom!
#1 - I mentioned this during the week. Take advantage of summer projects, internships, work experience etc. Science is so broad, so you it's really important to find out where your interests lie!
#2 - Work life balance. It's really hard to maintain work life balance when you see those around you working really long hours in the lab and writing papers and grants. Especially when it looks like they're getting ahead. Find out what work life balance looks like for you!
#3 - Success. There are so many ways to be a 'successful scientist' and being an academic is only one tiny fragment of that. Those working in industry, government, comms, are all still 'scientists'. Just because you're not at the bench, doesn't mean you're not still a scientist!
#4 - Personality. This kind of links in with #1, but find what type of job suits your personality. If you want to work in a basement lab and not talk to anyone all day, that's cool! I like working with people, so I love that my job involves working with others!
Honestly....I can't think of any others! Hope you've enjoyed my content this week! I've really enjoyed tweeting my work out and wishing you all good luck and happiness if your scientific journeys!
[admin] Huge thank you to Karyn for telling us all about the cool instruments and plasma magic. Do give @dr_karynJ a follow and listen to the podcasts where Karyn speaks about her science. 👇🥳🎙️🎧 Short - https://t.co/Bm9QigYwDX Long - https://t.co/GwAGJUXfrj
Muhammad Nauman
[admin] "Think Magnetically - Materials Around You" Please welcome @NKakakhail and listen to the podcast to know what is coming your way this week 👇🎙️ https://t.co/PR9Pwz8KYP
Here is the link of my first ever PhD paper. https://t.co/iMUVCfLoop. The details are coming soon in a long Podcast on Wednesday.
We are working on micron-sized crystal (50-90 micrometers). You know how much is a micrometer? Take meter stick (1 meter long) and make it's 1000000 pieces, 1 piece will be 1 micron. Average diameter of a human hair is 50-75 micron.
We all know that a current carrying wire (or motion of charges) produce a magnetic field but a bar magnet 🧲 creates a magnetic field without any connection to a battery? Why? Post your answer in comments without googling it.😀
Here is the link of my second Ph.D. paper. The research was a continuation of first paper and it was a joint venture. https://t.co/qwgjNpzErQ
[admin] "Think Magnetically - Materials Around You" Extended conversation with Muhammad is out now 👇🎙️🎧 https://t.co/npGd9veSdb
My Journey started from a govt school in Pakistan from a village name Ziarat Kaka Sahib. The school didn’t have basic facilities and we used to sit on the floor. But curiosity was there. I always used to think why there are different color flowers from same Earth & green leaves.
Every electron make a tiny current loop around atom and act like a bar magnet. All tiny loops (bar magnets) talk to each (adds up) other and show bulk magnetization. That’s how all the bar magnets are magnetic without external current (I.e. battery)
We started from stone age, went through bronze and Iron age, presently in silicon age. It seems that we are entering into a “Quantum age”. Quantum materials & Devices, Quantum computers, Quantum communication & information.
Our tiny cute crystal land on this table and start it’s journey from “under the microscope”. The crystal size is almost equal to the dust particle that can be seen in a beam of light through a room window). Crystal photo is coming soon.😀 @atthemicroscale @NKakakhail https://t.co/L4euQsYp8A
Look through the microscope lens. A tiny crystal is sitting there on the tip of the cantilever. The cantilever is of the size of human hair in diameter. @atthemicroscale https://t.co/D7IYtKoYcA
I completed my Masters degree in 2015 and published my MS research in 2020. The work was published in RSC Advances. Link of the article is given below. https://t.co/iiXBRMHcEl
[admin] We moved house! 🎉🏡🍾 You can now go to https://t.co/wX1p3xOMMV to find out all about Real Scientists Nano, our amazing behind the scenes team and every single one of our wonderful curators! https://t.co/14bVmh0DCH
Our Boss Dr. Kimberly Modic introduced a new technique of studing quantum material named “Resonant Torsion Magnetometry” when she was working at the Max Planck Institute. The work was published in Nature Communications. Link is below: @atthemicroscale https://t.co/qqeenwYJHM
Ahmad Kirmani
[admin] "Discoveries at the Interfaces" Please welcome @AhmadRKirmani and listen to the podcast to know what is coming your way this week 👇🎧🎙️ https://t.co/AwK8J7w4z1
Excited to be taking over @RealSci_Nano Sept 21-26. Lots of cool stuff coming your way this week! I will chat about my adventures in the nano world and my recent thrust on getting perovskites - the next-gen solar tech - into space!! #nanoscience #renewables #perovskites
Do you know this week is the Postdoc Appreciation Week? This is also the Peer Review Week. We will have lots to chat about! #postdoclife #peerreview
Quick introduction - My name is Ahmad R. Kirmani and I am a postdoc @NREL. I did my undergrad in Physics from India and then joined @KAUST_News for my PhD in Materials Sci & Eng. Subsequently spent a couple years working @NIST before joining NREL.
I have experienced multiple academic/research cultures, and have frequently switched research focuses - which I have found to be very helpful in shaping me as a scientist. I can't overstate the importance of exploring multiple research fields during PhD/postdoc!
It is at the interface of subfields that discoveries await. Interface is the discovery!
In my research career, I have explored ink-based semiconductors for next-generation optoelectronics. I have studied collodal nanocrystals, metal-oxides, and perovskites. In general, I make thin-films from these inks and manipulate interfaces and structure to control properties.
Perovskite solar cells made by my research group @NREL and me were recently launched to the @Space_Station via @SpaceX! Please have a look at this video! I am off to catch some sleep. https://t.co/IJ7wtGvZks
RT @konstructivizm: The United Kingdom seen from the ISS, (Credit: NASA) https://t.co/Ol5tUhWQVA
RT @realscientists: Hey folks! We're @BlackInMH! We are #mentalhealth providers, clinicians, researchers, scholars, students, activists, he…
RT @jacasiegel: The day I started seeing careers outside of academia as legitimate and rewarding alternatives, rather than crummy backup op…
Postdoc opportunities @OxfordMaterials in batteries. https://t.co/txY6HnbSIB
Here are some tips that can be helpful to grads planning a transition to postdoc career: - define your niche - choose a slightly different field than PhD - collaborate extensively - be active on social media https://t.co/aP4iGlXCPJ https://t.co/O82JeRjQsy
Nice postdoc opportunities in a fantastic research lab! @NREL Colorado is beautiful! #postdoc #renewables #perovskites https://t.co/V3oJVQ8uo6
RT @NASAPersevere: Where a human geologist would use a rock hammer to crack a rock open and look inside, I’ve got my abrasion tool to make…
It was great to have President Biden @POTUS visit @NREL recently. He talked about climate change and the critical role clean energy will play going forward. #climatechange #renewables #cleanenergy https://t.co/5fUy1CezaV
RT @ACSEnergyLett: ACS EDITORS' CHOICE Energy Focus "Molecular Triplet Sensitization and Photon Upconversion Using Colloidal Semiconductor…
RT @ecorson: Apply before October 8th to the 2022 Electrochemistry Gordon Research Seminar - we will begin accepting applicants on a rollin…
Quantum Dots (QDs) are semiconductor nanoparticles (2- 10 nm size) with tunable properties. These colloidal inks can be assembled into electronic devices via printing/coating. Applications include flexible large-area displays, solar cells, lasers. (1/3)
We recently wrote a review on the market potential of QD solar cells. Here is the front cover depicting the coating process. (2/3) https://t.co/dRG1ALp7ea
And yes - these inks glow! Here is a photo of some of the quantum dots I synthesized. (3/3) https://t.co/3Lvbhqz98z
Quantum Dots are expected to soon revolutionize the display industry. QD-televisions based on QLEDs will be the next superstar. Better resolution and display quality and less power-hungry than OLED displays. https://t.co/mEPe8PU7M9
And this again brings us to the topic of INTERFACES - the theme of this week! Being so tiny, Quantum Dots have a huge surface area. The surface (interface) defines their proprties. This interface can be manipulated to tune the dot's properties. Discovery awaits at the interface! https://t.co/mEPe8PU7M9
To hear more on Quantum Dots and what scientists are doing with them, give @NiNC_Seminar a follow! A seminar a week on the latest in QD research. https://t.co/mEPe8PU7M9
[admin] "Discoveries at the Interfaces" Extended conversation about science and more with @AhmadRKirmani is out now. Give it a listen! 👇🎧🎙️ https://t.co/Jnnbp5A2FH
Let’s talk about SYNCHROTRONS! These are giant circular machines – sometimes a mile or more in circumference – with the purpose of accelerating charged particles using giant magnets. As the charged particles dash through, they emit a broad continuous radiation (X-rays!) (1/n)
These precious X-rays are used to study matter. The materials and nanoscience community owes a lot to these user-facilities. These studies reveal fundamental understanding of atoms in materials we see around us. (2/n)
Using this understanding, materials can be manipulated to tune their properties, bringing them closer to the industry. (3/n)
Synchrotrons have played a big role in my research career. I have used the ALS, BNL, CLS and CHESS facilities to explore semiconductor thin-films. Primarily, I have looked at the role of microstructure using a technique called ‘X-ray scattering’. (4/n)
When the X-rays strike atoms in the semiconductor films, they get reflected. Capturing these reflected rays and decoding them reveals insights about how films are formed. In particular, I have studied large-scale fabrication of semiconductor films. (5/n)
Here are front covers of a couple of my papers with an emphasis on synchrotron characterization. (6/n) https://t.co/OKZm26DOTm
@BrookhavenLab @advlightsource @CanLightSource
Do you know what is the most important aspect of thin-films that allows tuning the microstructure and its properties – INTERFACES!
This is the beamline endstation at @BrookhavenLab that I mostly used during my stint @NIST X-ray scattering on metal-inks inks. IPad Air 2 likely uses oxides as its backplane technology. But those are not ink-deposited! Inks allow larger scale fabrication and are way cheaper. https://t.co/JsD6grTKJD https://t.co/II17ouP1wN
X-ray scattering allowed us to control microstructure of our oxide films, and achieve electronic properties similar to what industry currently uses. Look at the cartoon below to have an idea of what is microstructure. Flat crystals (left) in the films improve devices. https://t.co/LQdXyzhT0m
Automation is making its entry into synchrotrons too! We are entering an era of rapid discovery where these user-facilities will be equipped with machine-learning tools & robots to perform our experiments. Then, we will be able to focus on…mmm…being more active on social media! https://t.co/JsD6grTKJD
Here is a video I took of a robotic arm doing my X-ray scattering experiments at BNL!! The nice robot allowed me to take a nap during the early hours of that lonely morning. #automation #robot https://t.co/OEfU33ocBd
@buerviper Flat crystals are aligned along the substrate plane. So, less disorder/more texture. Charge tranport (mobilities) is an indication of trap states, and we found the mobilities to be 2x compared to the 'random' crystal growth. Here's the link: https://t.co/ZoGMdC564C
This is a great thread. Online courses on #MachineLearning https://t.co/aHoHYAuGwB
RT @konstructivizm: The biggest volcano in our solar system, Olympus Mons on Mars (h27km, w648km) by Radicek https://t.co/7PsGZsAjhi
Fantastic thread on Quantum Field Theory. https://t.co/0SAO33fsN3
It's #PostdocAppreciationWeek!! A sneak peek into the research of @NREL's Chemistry & Nanoscience Center's postdocs. https://t.co/T0tzYk3V92
RT @pickover: Mathematics, physics, flying. Visualization of the air flow field around the nose landing gear of a Boeing 777. https://t.co…
Thread coming up on Perovskite Solar Cells in a few hours, with a special mention of how they can also power future Space missions. Watch this space! #perovskite #solarenergy #semiconductors
Perovskites form the bleeding edge of research on next-generation solar cells. These are low-cost semiconductor inks that can be converted into optoelectronic devices by simply casting them onto a surface using coating techniques. (1/n) https://t.co/FuoltrK8zi
Here is an observation that has really surprised the community: this low-cost/dirty way to making cells from perovskites yields properties that have been observed in highly pristine Silicon and III-V semiconductors! (2/n)
Any defects in the conventional semiconductors can ruin their properties – but perovskites don’t really seem to care! They are defect-tolerant. (3/n)
Power-conversion-efficiencies as high as 25% have been reported for perovskite solar cells, and several start-ups around the globe are trying to commercialize them for terrestrial applications. (4/n)
A low-hanging fruit is a tandem solar cell that can combine the benefits of the age-old Silicon cells with perovskites. The extra power tandems will deliver will drive the solar costs down, helping us combat climate change faster. (5/n)
And Perovskite solar cells are attractive for beyond-Earth applications too! To power future space missions. Space presents severe challenges to solar arrays that power missions. Radiation (protons, electrons, alpha) is one of them. (1/n) https://t.co/FuoltrK8zi
It’s being found that perovskites are several times radiation-tolerant than the conventional solar technologies (Si, III-V) that currently power satellites! We recently launched our perovskite cells @NREL to the @Space_Station with @NASA. Let’s see how they perform!
Here is the NREL team behind the @Space_Station launch of perovskite solar cells. Also, me making cells ;-) https://t.co/FuoltrK8zi https://t.co/62nZ258O8J
....And synchrotrons can detect earthquakes too!! @ANSTO https://t.co/1Bjy0Pkkiy
Antarctica from Space! https://t.co/CkurGcxPVd
INTERFACE will be the highlight of my tweet thread later today. The basic tool to explore interfaces & surfaces is: Photoelectron Spectroscopy (PES). This can be done in-house or at synchrotrons. Here is how an PES system looks like (my 2021 front cover). Stay tuned! #SciArt. https://t.co/OUrXMwHorb
Hope you all are having a great weekend! Here are some facts on Photoemission Spectroscopy (PES) - a great tool to have in the toolkit of a materials scientist. /1 https://t.co/WAeNKIofRC
PES is based on the photoelectron effect. The sample to be studied (film, powder, crystal) is excited with photons of a certain energy. The electrons emitted from the sample upon absorption of these incident photons are collected and parsed for crucial info about the sample. /2
There are 2 modes of PES. One uses high-energy X-ray photons (>1000 eV) and studies the chemical composition. Chemical environment, oxidation states, etc can be clearly explained. This is called XPS (X-ray photoelectron spectroscopy).
When low-energy photons (usually UV) with energies in the range of 10s-100s eV are used, electrons that form the valence band structure of the sample are detected. This is UPS (Ultraviolet photoelectron spectroscopy).
UPS reveals information about energy levels, work function and defect states. Great tool to study optoelectronic devices!
Great thing about PES is that it's highly surface sensitive, and a usual in-house system gives information about the top 1-5 nm of the sample surface! Thin crusts and interfaces can be studied in detail - Interfaces that define optoelectronic devices!
I have used PES extensively – both in-house and @CanLightSource – to characterize interfaces in solar cells. https://t.co/WAeNKI6Et2
These studies revealed a wealth of insights into nanocrystal and perovskite surfaces, specially on how the environment interacts with these materials, and what strategies need to be in place to make more stable optoelectronics.
The #COVID19 lockdown during the summer of 2020 allowed me to hone my #sciart skills. Cool science illustrations are a great way to get your point across and to publicize your work. Have a look at my recent Front Covers I rendered using @Blender. Follow @andrewpprice! https://t.co/44Aem0zrHG
It was a lot of fun curating this account over the last week!! Hope you enjoyed the discussion on INTERFACES! Give me a follow @AhmadRKirmani to know more about my research and fun things about nano. Here is a more detailed peek into my research: https://t.co/pmMKvr1tLe https://t.co/FUELsO6nxw
[admin] Thank you @AhmadRKirmani for a wonderful week for science. Do give him a follow! Podcasts featuring Ahmad are here - Short - https://t.co/AwK8J7w4z1 Long - https://t.co/Jnnbp5irO9 https://t.co/osODMWLVEk
Niklas Friedrich
[admin] "Getting in Shape: Spinning for Nanographene" Please welcome @cienciaparaelf2 from @nanoGUNE for a week of science and listen to the podcast to know what is coming your way this week 👇🎙️ #UnderTheMicroscope #podcast #sciencepodcast https://t.co/9QWfkw9Nhl
Good morning! I am Niklas Friedrich, a PhD-student working in the group of @NatxoPas in @nanogune! I’m looking forward to discussing #surfacescience, #magnetic #graphene and #work-life balance here in the coming week. Please ask lots of questions!
To start: This is “my” machine. A homebuild #ultrahighvacuum chamber, and a #cryostat and a look inside the chamber, where we prepare the samples (banana for scale) https://t.co/hyzMxIxtT3
The heart of it all: a #ScanningTunnelingMicroscope or #STM, what a beauty! Inside the chamber it is hidden by thermal shields, but outside it is showing its whole beauty. Fotos from before and after mounting lenses to collect light and a low temperature #AFM amplifier. https://t.co/IsMo8dkizu
@AndrewR_Physics The head is a commercial slider-head from createc. The chamber around it is designed by us
@ulrich_hofmann @NatxoPas @nanoGUNE There are a bunch of ways to get spin-polarization into graphene. Two examples are: #topological #bandengineering in #graphene #nano|ribbon. Or in small nanoflakes an imbalance between the two different sublattices. Check the publications of @Springfetopen for details and refs
What can we do with it? We can look at single #atoms or #molecules like these: Thanks to Stefano for the image of the atoms https://t.co/l2EXgvckii
How does it work? Imagine being an #electron in a metal, you are free to surf around your wavefunction anywhere in the metal, actually, even outside the metal! Physically speaking you can “penetrate into the energy barrier” #Donttrythisathome https://t.co/fgiKIcLqm1
If you find another piece of metal in that tiny distance you can jump there. This is called #tunneling. If there is a bias voltage applied between the first and the second metal piece, we can measure the current flowing, even if the two metal pieces don’t touch
In the experiment we move a sharp needle, the tip, very close to the surface that we want to look at. Changing the distance between tip and surface by about one atom changes the current by a factor of ten!
Ever used an electric lighter? You press it, this creates a bias voltage and a current flows. We use it the other way round. We apply a bias voltage and the piezocrystal squeezes together some fraction of a #nano|meter. That’s how we move the tip so precise.
Now we only need a tip that ends in one single #atom and we can get beautiful images… okay, and a sample to look at… https://t.co/kzswMURldU
Our project partners in @springfetopen at @IBMResearch in the group of Leo Gross are experts in #AtomicForceMicroscopy. It works almost the same as an STM, but with forces instead of current, that way they can work on insulating samples
Can we go smaller? Of course! Placing a single CO-molecule on the tip apex of your microscope will give you #atomicresolution inside a single #molecule (sadly though, it is hidden from the public by a big paywall since 12 years) doi:10.1126/science.1176210 https://t.co/liLb0g42YQ
During my master I worked on another exciting #research project: #ScanningQuantumDotMicroscopy or #SQDM in the group of Stefan Tautz at @fz_juelich This is a very underrated technique, a powerful tool to image #electronic #surface properties.
I worked with #PTCDA, but it works also with other #molecules. It is an incredible technique where you use a single #molecule hanging from the tip of an #AFM to measure electric #dipoles on the surface with atomic precision. https://t.co/85ETaNMAfF
You can even stand up PTCDA on the surface and it does not topple over. So far, it is not fully understood, how this is possible, but I assure you, it works. #discovery #science #howdoesitevenwork https://t.co/y9BrcP9IEr
Today, I will tell you what I do all day. #ADayInScience
Here is some actual footage of me, reading papers (I hope they are #openaccess) to get ideas or understand better, what could go on in my experiments #ADayInScience https://t.co/ynbYDGCSH8
@quantizedfella That is a tricky one. I never thought about it, as I started off in a UHV research group... There are some textbooks around on vacuum technique, but I don't know them enough to recomend any. Sorry
To prepare a tip, that ends in a single atom, I dip it few #nano|meters into the metal sample and pull it out again. Over and over, recording images in between until I am happy. A little bit like this #ADayInScience https://t.co/tXsrYBxKMG
After three hours of unsuccessful tip forming it will look more like this #ADayInScience https://t.co/uFjEoNKBxZ
The images are recorded pixel by pixel. So each #ScanningTunnelingMicroscope image you will see probably took something between 5 and 30 minutes to be recorded, not counting the time for tip preparation #ADayInScience https://t.co/4env7mgvlj
After gathering the exciting data, everything needs to be analyzed. My tools of choice are @WSXM_official for images, SpectraFox for a quick look, Phython for more detailed analysis and nice looking plots and @inkscape and @overleaf to put everything together. #ADayInScience
Something I need to learn is how to organize my evaluation routines better using #git. Being able to code and develop software is a big plus for #scientists. #ADayInScience
Talking about collaborations: Of course, I am not alone doing research, big part is done together with my colleagues in the lab from #nanoimaging in @nanogune like @MartinaCorso3 and @Frank96R #ADayInScience
With this results let’s go to our collaborators from theory and discuss! I am lucky to have a bunch of collaborators directly in Donostia at @CFMdonostia and @DIPCehu Check out their profiles as well: @sofia_sanzw @Aranko @thofrederiksen @DanielS96184926 #ADayInScience
Or in the context of @springfetopen with the chemists in the group of @depena33 and with other characterization labs around Europe from like the people at @QM_Oxford (ESR) @IBMResearch (AFM) and @tudelft (MBJ) #ADayInScience
I cannot stress how important it is, to talk with other #scientist. This is the most fundamental part of #research, continuous discussion, yes, also with coffee. Or in the evening over a beer 😊 #ADayInScience https://t.co/DvkqQtZqKy
The cryostat to #cool the sample to 4 Kelvin needs to be filled with #liquidnitrogen every two days and with #liquidhelium every five days. #ComingToWorkOnSundays #PlanAhead #ADayInScience
[admin] "Getting in Shape: Spinning for Nanographene" Extended conversation with Niklas (@cienciaparaelf2) from @nanoGUNE is out now!👇🎙️ https://t.co/wCdyWB7fXy #UnderTheMicroscope #podcast #sciencepodcast
Having heard about my day a lot yesterday, I will try to put a little bit together the #science of #nanographene|s that I am doing. Of course, this list cannot be complete, check the people I mention for much more exciting #organicmolecules #spin #physics
In the #podcast I tell you about our paper in @PhysRevLett together with @NatxoPas @DanielS96184926 and @depena33 groups. Here you can read it in full length, learning about #topology, #magnetism and #spin in #graphene #nanoribbon|s https://t.co/itFvxDcRc7 https://t.co/zSxEcLyrWQ
@gudrun_lotze You rise a very important point here! I think it is necessary to develope ways to have more inclusive models for "coffee-like" interaction. For example, local hubs for conferences, connecting different sites all over the world. Or things as simple as fast and stable internet.
@gudrun_lotze I think it has to do a lot with the low effort translating other aspects than scientific contributions. eg: -running into someone and ask a quick question (there are concepts around it, like a conference as a videogame, the chaos computer club did great effort there last year.
@gudrun_lotze - sitting together for lunch and discuss in more detail. Proper video-conferencing systems in institutes, at best with options to have food delivered, could be an option
@gudrun_lotze - during a conference where you travel to, you are not expected to do other stuff. When at the institute, there is still pressure to sit in the lab, listening to the talks. Having dedicated spaces for meetings could help.
@gudrun_lotze What else is missing? I am missing a bit of creativity to create something new. It feels like the scientific comunity is a bit too conservative about this. Although I understand where this mindset is coming from.
Using #graphene #nanoribbon|s in #tunneling contact as beam splitters for #electric current, a very nice theoretical paper by @sofia_sanzw and @thofrederiksen in @PhysRevB https://t.co/06TPcDijDA
Two papers appearing in @Nature b2b using #topological #spin states in #graphenenanoribbon|s to construct topological SSH-chains. What a marvelous meta-concept!👏👏👏 @FaselRoman @BerkeleyLab @Empa_CH https://t.co/4t34zkxfd0 pdf available here https://t.co/TU2mjTX7sn
If you got hooked on #graphenenanoribbon|s, here is a great #review from Meike Stöhr in @RoySocChem to start learning more about #spin in #graphene and find many great papers https://t.co/YrPpKrNNXQ
Exciting work combining #STM and #light to #STML by Shuiyan Cao, @ARoslawska and Guillaume Schull published in @NatureChemistry. Take a look here at the @Arxiv version of the paper: https://t.co/RZLHJJnOue
Did not pass #peer-review yet, but nevertheless it is exciting work published on @arxiv by groups of Jelinek and Ecija. You can see how much effort they put into it, look at that beautiful #AFM-images https://t.co/gvueII0JLW
Katharina Kaiser solving the open questions of #cyclocarbon #chemistry one by one at @IBMResearch with exciting #AFM results here in @ScienceMagazine https://t.co/4bljBQHXzP or maybe taking a look at @arxiv
I learned so much reading this #openaccess paper in @NatureComms! It is a great step forward understanding the unintuitive #manybody #physics of #quantum systems from the group of Andreas Heinrich @EwhaWomansUniv https://t.co/NeZ0SJDy3f
Fascinating #surface #chemistry and #lowdimensional #physics. 0D, 1D and 2D structures of a N-doped triangulene derivative by @SMaier_group published #openaccess in @NatureComms https://t.co/eYQG5qSBxX
Exciting work on #triangulene chains and circles and #manybody #physics from @mishshan in the group of @FaselRoman just out in @Nature, get access to the paper here https://t.co/FAJXXsxHPD
Just for that wonderful #STM images this @NanoLetters paper from @Lugroup_nus group is worth looking at. But the #spin #physics of #triangulene is also pretty cool! Good thing you can get passed the paywall here -> https://t.co/qzzsnTHfnK
Pushing the limits even further, #attosecond and #picometer resolution in #STM @mpifkf in @ScienceMagazine https://t.co/bZ4cFPwVvC
Multi-tip #STM #AFM, but coming from two sides to image a suspended #singleatom thick #graphene layer! Exciting, as in the experiment you never know how your tip looks like #spitzenforschung from Jannik C. Meyer group in @SciReports https://t.co/1x0YUOqrOl
Combining #microwaves and #superconductivity, getting amazing results and then presenting it in such a clear and didactic manner in @NaturePhysics. Great work from Katharina Franke’s group at @FU_Berlin https://t.co/VNBJE7stbD
So many exciting results here during the day. I hope you found an interesting read or two as well! I enjoyed a lot reading the mentioned papers. Have a good evening everyone! 👋
Today, I will reflect on the #working conditions in #resarch. Spoiler alert: They are not very good for most #scientists, and I think they are not even good for #science.
#WorkLifeBalance for #scientist... Wait, there is a life that is not related to work?! https://t.co/KTO42g1rEX
Reading my tweets about #science and #work|ing in science? Would you like to work in science or #academia? Tell me why!
You are essentially a #selfemployed #scientist, although you work for a university or institute. It will always be your name on the #publications that counts. If you want to keep doing what you do, better invest a 👉lot👈 of time
If you want to #stayinresearch, you are competing over #money (salary or to spend) against everyone in #science, many times even against people from very different fields. The metric you compete on: #paper|s and #citations
As #science is a #creative process it is difficult to judge what is good science and what isn’t. To come up with “objective” criteria, #scientists are judged mostly by their written, hopefully #peerreview|ed publications, mostly in expensive journals
You are forced to focus on publishing as many #paper|s as possible, because #citations, number of #publications and #hindex are very important factors when you apply for a scholarship, a grant or a position at an institute or university.
I guess you get an idea, why there are #scientists publishing #junkscience in #predatorjournals, a practice that is obviously bad and hurts #science. Still, I understand the structural dynamics leading to these decisions.
The #publishorperish mentality is clearly not in the interest of the individual, as it incentives to push yourself beyond the limit. #Depression and #Anxiety are very high under #PhDs. #mentalhealth is only slowly leaving the tabu-status @Nature https://t.co/C8YwAh9DFo
Bad for #scientists, good for #science? No. #Science is a creative process that connects ideas, you need time to play around, to try, most importantly to #fail! Focusing on publishing many #papers forces you to take tiny steps forward. #IncrementalScience
Me, taking over a twitter-account and telling you about my #science likely won’t be valued, neither organizing this a twitter account, which takes a lot of work from people like @MySci_PK, Sanket Dash and @svenja_lohmann. Work, that isn’t spend on writing the next paper.
RT @starstrickenSF: @ young people, especially young women interested in STEM! i’m giving a (free!) talk this evening on my journey in astr…
On @nanogune’s website you can see I am an FPI fellow. My #salary can be found publicly. After a minimum 5 years of studying (in my case 6 years) I get 16.422 Euro/year before taxes for 4 years.
In Germany the full-time #salary would have been higher, but many #PhD students are not employed #full-time. Of course, they are expected to work full-time. #Fair #IchbinHannah
If you plan to continue doing #research as a #PostDoc you will feel likely a lot of pressure to #work more hours because there is very little #money they you compete for with some of the smartest people on the planet.
Plan to have a family or stable relationship? Sure, just make sure they are comfortable moving every 1-3 years to another country for your next #PostDoc while you try to find a #tenure|track position. 🌟Extra points, if your partner is in #science, too🌟
The dropout rate of #WomenInScience after the #PhD is much higher than for men. A clear sign of #structuralsexim, of the (white) men club of #science. All male #Nobelprizes show that there is still a long way to go Look for initiatives like these: @nanoGUNE https://t.co/Vj81bxshlm
@nanoGUNE Here is a starting point from where you can learn more about the issue https://t.co/FwTGFMo52v
So, why do I want to stay in #science? Because I am #passion|ate about what I do. Very passionate. I find it incredible exciting to look inside single #molecule|s and move them one by one. To advance the collective human #knowledge.
#Science is #beautiful https://t.co/YKVAw1eiow
@ShadyNeutron The structural working conditions are not good. True. However I enjoy doing my PhD, both thanks to my colleagues, my passion for science and my curiosity! As I said in the podcast. Make sure you spend your time with people you enjoy being with, also at work.
@CaboAntonija I wonder about causalities here... 🙃
I have met many very bright people in my #research. Both in my workgroups, as well as the institute, going to #conferences, #workshops, #seminars, meeting people on #labvisit, #research exchanges, sabbaticals… There is so many opportunities, so much to discover!
I get the trust from society to spend a lot of money on my ideas and I am relatively free to decide on what I want to work on. https://t.co/cCdXGsOot0
Another thing: Most #scientist|s are aware of the terrible working conditions and will try to work ways around it. Organizing your work hours very flexible with your collaborators is normal. Still, you will have to work a lot.
Today is going to be a tricky one 🙃 Let’s see, if I make it past the trolls: Let’s discuss #sciencedenial and being politically active as a scientist today. relevant xkcd: https://t.co/psj4kThJ64
I think, as a #scientist you are morally obliged, to #speakup to people undermining actively a scientific world view. Hold up scientific standards, if it is not your field, you should try to represent the #scientificconsens as good as you can
Speaking up against #sciencedenial is tricky, first you need to notice it. There are very clear examples that are summed up extraordinary well here: https://t.co/tGfTcHFad4
There are great and fun resources to learn to quickly identify flawed arguments. #Fight #disinformation with a cranky uncle https://t.co/0GRzJJoHXx
Today, you should go out and protest against the #climatecrisis forming part of the #globalclimatestrike. Every politician not taking quick and focused action to reduce #greenhousegas emission now is to some degree in #sciencedenial #UprootTheSystem
Here is a great infographic about #sciencedenial. Noticed the “global warming hoax”? https://t.co/PbXQEaEZ9e That is where it starts to become uncomfortable. Especially on the day of #globalclimatestrike #UprootTheSystem
Here are some more #climatescientist: follow them! #UprootTheSystem https://t.co/HZnqqdAApA
From a scientific point of view initiatives like @AlleDoerfer and @ende_gelande are completely right in claiming we need to stop destroying villages and nature and need to #stopfossilfuels and #stopcoal #UprootTheSystem
The key finding of the 5th #IPCC report from 2014(!) is that there is essentially a linear relation between CO2 and temperature. More CO2 = hotter = severer #climatecrisis #UprootTheSystem https://t.co/zZSFEJxLuv https://t.co/blYVJbHXKg
I am aware, I am not the best expert on the #climatecrisis that one can find, but I can represent what is the #scientificconsensus says, thanks to @ScientistRebel1 leaking the next IPCC assessment report AR6. #UprootTheSystem https://t.co/HMtov4FNUv
There are many structural changes we need in #society. I tried to come up with a list of things that can change quickly in #science and #academia: Add your ideas on how to reach #sustainablescience #UprootTheSystem #ClimateAction
If your #research is somehow related to #sustainability, reach out to politicians to explain consequences of the #climatecrisis relevant for them and offer advice. This can be on a communal, local, regional, federal or even global level. Whatever suits you!
Research centres like @nanoGUNE have huge electricity consumption, make sure this comes from 100% #renewable energy sources #UprootTheSystem #ClimateCrisis #ClimateAction (feel free to tag your institute to make administration aware of the issue)
Go to work by #bike🚲#publictransport 🚌 or #walkingsbrilliant🦵🦿, no matter your position and salary Make sure your institute has showers or at least changing rooms with the option to wash oneself
#Dontfly to a conference on the same continent Offer options to participate remotely If you would have to fly, ask to contribute via livestream instead If you can’t avoid flying, make sure to stay long time, combining several conferences and lab visits
Over #sustainable menus at canteens and conferences
Use your #privilege|s to help the less privileged. There are many ways to support: from focusing research or media attention on aspects of the #climatecrisis over being present at protests or help washing the dishes at protestcamps to just donating money
Be creative, another world is possible! 👏👏👏🎉🎉🎉💚💜 😊 https://t.co/E4lDsQvEmJ #UprootTheSystem #ClimateCrisis #ClimateActionNow
Must read for #scientist: The #IPCC reports at https://t.co/4iWioAxOKl for their way to make information accessible. Clear language, clear structure and a fractal of information. You find the longer explanation on the next level, going from the summary, to chapters, to papers.
Another group providing valuable info are @S4F_INTL and the national and local groups of #Scientist4Future providing lots and lots of resources for example to #FridaysForFuture #UprootTheSystem
Do not forget who is fighting hardest to stop the #climatecrisis: #Indigenous peoples from all around the world are as good or better than natural reserves in protecting #biodiversity #UprootTheSystem https://t.co/L1uSz9eYGQ page 32 https://t.co/vTuv7bpg43
RT @PaulMougeolle: Today, researchers published an enlightening paper on Total's past climate knowledge, lobbying and greenwashing. Main ta…
Everyone denying that we need fast action #rightnow to avert the #climatecrisis is in #sciencedenial. The current #growth-based #capitalism is destroying our fundaments of survival and cannot go on #UprootTheSystem @fff_europe @S4F_INTL @ScientistRebel1 @Greenpeace @ende_gelande
It was a lot of fun taking over this twitter account the last week! Thanks to all of you who read my tweets, I hope you had a good time! I am typically less active on my personal twitter account @cienciaparaelf2, but if you feel like following me, I would be honored👋
[admin] Thank you Niklas for a wonderful week of science. Do give @cienciaparaelf2 of @nanoGUNE a follow! Podcasts ft. Niklas are here - Short - https://t.co/9QWfkvSbSL Long - https://t.co/wCdyWBoQP6 #UnderTheMicroscope #SciencePodcast https://t.co/8XHbzmEa7F
Giulia Pacchioni
[admin] "Materials Science - Hot from the Press" Please welcome @Giulia_Pacc and listen to the podcast to know what is coming your way this week 👇🎙️🎧 #UnderTheMicroscope #SciencePodcast https://t.co/CFO9A0IxuA
Hello! I’m Giulia Pacchioni, @Giulia_Pacc, tweeting for the week from London! I’m a Senior Editor at @NatRevMater, where I handle content on a broad range of topics in materials science. This week I'll share some tips on writing, publishing & on life as an editor. https://t.co/IcErSb0ryN
Today I will put the spotlight on editorial jobs, telling you about how my own path led me to this fun career and what an editor actually does.
I'm a physicist by training: I did my master and bachelor degrees at @LaStatale in Milan, then moved to @EPFL_en in Lausanne for my PhD. I worked with scanning tunnelling microscopy, something you have learned about last week from @cienciaparaelf2! Here's me with my STM in 2014 https://t.co/azlAnsfwGc
My PhD project, in Harald Brune's group, involved studying how (and why) small molecules self-organize on surfaces & how the patterns they form can be used to template the organization of atoms & clusters with cool catalytic/magnetic properties. STM pictures in silly colours ⬇️ https://t.co/xV7aewaV2D
As I was nearing the end of my PhD, a friend pointed out that an editorial job would bring together all the things I was passionate about: physics, writing, and science communication. He was right!
I started collaborating with blogs discussing science and co-organized a summer school to tailor my CV to this type of job, and landed a position on the launch team of @NatRevMater, which was, and still is, my dream journal 🙃 https://t.co/CYukVsMMM1
Over the years I have also worked with @NatRevPhys to prepare their launch in 2019, and for a few months with Nature Materials. I will tell you more about how to find editorial jobs and what an editor does in my next threads! https://t.co/lwd9Spi5yd
Let me tell you more about my job as an editor at @NatRevMater. We are a team of 3 (with @ChristineHorejs & @arianevartanian) and publish Reviews and Perspectives on all topics materials science, + Comments on topics such as mentoring & inclusivity in academia. Lots of variety! https://t.co/TmtcxQJev6
Editors also write content such as Research Highlights & Editorials -- the latter require a lot of reading and thinking and are a stimulating team effort, such as this recent one led by our brilliant team member Ariane: https://t.co/gUVSol0jcS https://t.co/taZin0y0zp
As editors we need to know what’s new in the fields we cover; we keep up to date reading the literature and going to conferences & talks (now virtually!) to identify both timely topics and interesting authors. We also encourage unsolicited submissions. https://t.co/LLvSEGGddW
We ask authors to prepare an outline of their Review planning how much content to cover, how to structure it, and ideas for figures & tables; we give feedback on the outline trying to ensure the angle of the article is clear and the amount of content appropriate https://t.co/JJfCGOksNm
We then keep in mind the submission timelines of each manuscript and check on authors regularly. We publish a fixed number of articles per month, so it’s important to ensure we have a steady number of submissions through the year, but we also need to plan for unexpected delays
Once submitted, if a manuscript is not in top shape we suggest ways to improve the structure, clarity & accessibility of the text and to make the figures easier to understand and more useful for readers. https://t.co/Cct4ieWNF1
As you have guessed, the next step is to find expert reviewers to comment on the manuscript and, when the reports are back, guide the authors through the revision process https://t.co/6WsKGtW7GS
The most involved step of the process is the in-depth editing of the text to ensure every paragraph is clear & precise and the writing concise. Our art editor applies our colour palette and fonts to all figures & redraws schematic so they are all consistent across the manuscript https://t.co/47Q3TSIDMk
The final step is checking the proof to ensure everything is in good order before publication, and enjoying the article in its final, highly polished form. Publication is always a proud moment, sometimes the culmination of a process of over 2 years since inviting the author! https://t.co/2rULyvZI1e
[admin] "Materials Science - Hot from the Press" Longer conversation with Giulia (@Giulia_Pacc ) is out now 👇🎙️🎧 https://t.co/Opn4iwod2W
Have you ever wondered what the Nature office in London looks like? It’s a cool mix of old and modern in a former warehouse on the Regent’s canal. It was very recently refurbished and sometimes I still get lost while looking for colleagues on other floors! https://t.co/QpE36ddrW8
The office is open space, but there are little nooks & quiet corners where to go for a chat or for some focused work. My favourite desk is near a big window overlooking the canal & a mooring with several houseboats. Lots of cats living around the boats to observe during breaks! https://t.co/xDRn8PvXDS
Editors own the weirdest things. The craziness is now down because we've just moved all desks around so lots of personal stuff was taken home, but last week I found the cutest fluffy antibody bound to its little antigen. Also lots of interesting books are scattered around. https://t.co/uxwbwkmtdL
The best feature of the office though is the Nature archive, where physical copies of every issue of Nature ever published are kept. Here are some pictures of random articles from 1874, 1989, 2000 & 2013. Fun to see how the look of articles has changed! https://t.co/cr6qiEY9YK
Finally, here is me enjoying the best window desk! https://t.co/YAvTC43CiX
Let’s now look at some simple writing tips. The main thing to keep in mind when writing scientific articles is that the point is not to write beautiful prose, but to be understood clearly. We are not Shakespeare! In our case, clarity is better than beauty. https://t.co/48FAZYsbtZ
You want your paper to tell a story. Start with your scientific question & how it fits in the context of previous results. Then state what you did & how (in logical, not chronological order) and what you found. Finish with *reasonable* implications and next steps. https://t.co/OQFhxDHma9
Use a clear structure to guide the reader. One paragraph, one idea. Use short sentences linked by appropriate connectors (therefore, however) Use simple but precise words, always using the same word to describe the same thing. Avoid empty words (very, quite) Define all acronyms!
Metaphors can be confusing, and we often don’t realize how strongly related to our own culture they are. We don’t all grow up with the same myths and stories, hence, if you don’t want your metaphors to become your Achilles’ heel, avoid them. https://t.co/DA9KnMRQMW
As a reviews editor I get often asked ⭐What makes a good Review?⭐ Here is a summary of my answer in 8 points: 1- Timely: cover an emerging topic or address a need for clarity in a specific area. Make sure you can answer the question ‘why now?’ before you start writing. https://t.co/2tc41jk3PP
2- Original: ensure you have a new angle/message such that the new review is a useful contribution to the literature. Writing a good review is a lot of work, so make sure the final product will be valuable for readers. Make it count! https://t.co/rxHxrztMXw
3- Insightful: you don’t want your review to be a laundry list of results in the field. Use your experience to select the most important results, assess them critically and show readers how they fit together in a bigger story https://t.co/qKe0kZnMQD
4- Balanced: cover fairly the contribution of the various groups active in the field. If there are different points of view, acknowledge them. It’s not always possible to be fully comprehensive, but make sure you clarify what is your focus and how you selected the works to cover https://t.co/ViDxGHqY8Y
5- Accessible: explain non-obvious concepts, use clear definitions and briefly introduce the important ideas in the field so newbies can delve into the topic. Reference tutorial reviews where the can learn the basics. https://t.co/qzeFnSrSLY
6- Well illustrated: mix published figures that exemplify important results in the field and new figures such as schematics of processes & graphs comparing results or showing trends to illustrate your main points clearly and effectively https://t.co/x8r4YOe0xS
7- Forward looking: think carefully about your conclusions and perspectives: What are the open problems in the field? What are the promising directions? Here is the place where you can be a bit more opinionated and discuss your own insights on the future of the field https://t.co/Q6HXTf3li0
8- Well-planned: once you choose a journal for your review, discuss with editors to see if they have suggestions on the focus or specific guidelines for length and format. Do this before writing the whole thing! This step can save you a lot of work revising.
The topics I want to cover today are ⚡️cover letters⚡️ & ✨appeals✨. What's the point of a COVER LETTER? It is your opportunity to briefly highlight the main point & significance of your work. Don’t copy and paste the abstract! Editors read both. Keep it brief & to the point. https://t.co/9Nkk3ziErY
A common question is how to address the letter. With ‘Dear Editor’ you never go wrong. Avoid ‘Dear Sir/Madam’: it’s outdated, and the editor is likely a Dr anyway! Check out this blog post by @stuartcantrill for detailed cover letter tips: https://t.co/mQnBLxAQyT
APPEALS: Not happy with the editor’s decision? You can always appeal. Make sure you clarify any misunderstandings & explain why you think your paper should be reconsidered. Don’t just ask the editor to rethink their decision: add new data/information to help change their minds.
Avoid just stating how much your previous articles are cited, or insulting the editor & reviewers. Be polite and use constructive arguments to make your point. Appeals take time, so avoid just ‘trying’. Read more in this @NaturePhysics editorial: https://t.co/pSIfABhAn6
I was forgetting to share a useful resource: a great @NatRevChem editorial discussing how to pitch review ideas to journals: https://t.co/QZYPZrjNe6 https://t.co/5uNXlquDYu
Let me tell you what I love about being an editor, and why it’s a great career option for those who don’t wish to go down the academic career path, but want to keep having fun with science
As an editor, you work on a variety of tasks, including reading, making decisions, editing & writing, and you're exposed to a broad variety of topics. You get to interact with a lot of passionate scientists at all career levels. It’s rarely boring!
Editors travel quite a lot: in non-pandemic times I used to attend a couple of big conferences a year (such as APS & MRS meetings), plus several more focused conferences. We also organize lab visits & give publishing talks. I have visited a lot of amazing places through my job!
A big advantage of editorial jobs is that they're secure and flexible. Meeting publication deadlines can be stressful, but generally the pressure is much lower than in academia. Note that things can be different at different journals, this thread just reflects my own experience🙂
So, how to find editorial jobs? A good place to start is the Nature Careers website, https://t.co/RT9n5PMbPO, where you can find listings for editorial jobs both at Springer Nature and other publishers. Don’t be shy to reach out to editors on Twitter if you have questions!
A good way to add to your CV something valuable when applying for editorial positions is to co-organize a conference: it showcases organizational skills, enthusiasm & the ability to select good topics. For example MRS Spring 2023 is looking for organizers: https://t.co/dtKaU467lN
[admin] Huge thank you to Giulia for taking us into the publishing world. Do give @Giulia_Pacc of @NatRevMater a follow! Podcasts ft. Giulia are here 👇🎧🎙️ Short - https://t.co/CFO9A0IxuA Long - https://t.co/Opn4iwFNUu #UnderTheMicroscope #sciencepodcast
Tiffany Harte
[admin] "Creating New Quantum Materials Atom by Atom" Please welcome @UltracoldTiff of @Cambridge_Uni and listen to the podcast to know what is coming your way this week 👇🎧🎙️ #UnderTheMicroscope #SciencePodcast https://t.co/WqpmdBz6Oe
Hello! I’m Dr Tiffany Harte (aka @UltracoldTiff), a postdoc in the many-body quantum dynamics group @CaMBQD in @DeptOfPhysics @Cambridge_Uni. Join me this week to read about Ultracold Atoms and their applications, and get a glimpse into my week as a scientist! #ColdAtoms
How cold is Ultracold? https://t.co/T3Q24FmTOI
Absolute zero is at 0 Kelvin, or -273°C - this is the lower limit on absolute temperature and it becomes increasingly difficult to reach the colder you get (negative absolute temperatures are an interesting but separate discussion!).
Water freezes at 273 K, and the Antarctic can get as low as 190 K. Cryogenic systems can use e.g. liquid nitrogen (77 K) or liquid helium (4 K), but are limited to a few mK. Even outer space is around 2.7 K from the cosmic microwave background. We need to go much colder!
A cloud of atoms can be cooled down to temperatures approaching absolute zero - commonly a few hundred nano Kelvin (nK - a billionth of a °C) but sometimes as low as tens of pico Kelvin (pK - a trillionth of a °C) - more on how to do this later!
I’m referring to a ‘cloud’ of atoms because we work with a dilute gas of atoms held inside a vacuum chamber. Each cold atom (or molecule) experiment will be carefully designed around a small number of atomic species depending on the application.
The temperature of the atom cloud is related to the velocity distribution of the atoms. To cool the cloud, we want to narrow this distribution and reduce the atom velocity. Tune in at lunchtime to find out how!
How do we cool atoms down? (Part 1 of 3) https://t.co/9mjaTNtioG
There are lots of ways to cool an atom cloud, and the methods used will vary between experiments and different atomic species - but there are a few methods that many experiments have in common.
Here’s a photo of a potassium source: we buy the source in a sealed ampoule and place it inside our vacuum. We break the ampoule and the source gradually vaporises (sometimes helped by heating). These ampoules should produce enough atoms for several years of operation! https://t.co/O8g4qspD2B
Once we have enough atomic vapour we use lasers to slow the atoms down and reduce their temperature - lasers don’t just heat things up!
If the laser beam is at a wavelength that matches an atomic transition, an atom can absorb photons, transferring the photon momentum to the atom. When the atom returns to its ground state and releases a photon, this gives another kick, but in a random direction.
So if we want to slow down an atom then we need to make sure that it can be cooled from all directions, but preferentially absorbs photons from a direction that opposes its motion. We use the Doppler shift to achieve this!
If we set the laser to a slightly longer wavelength than the transition, an atom moving towards that laser beam will see the light Doppler shifted to a shorter wavelength - back into resonance with the transition and more likely to be absorbed.
To make sure that we can slow an atom moving in any direction we overlap three orthogonal pairs of beams propagating in opposite directions. This is called optical molasses because it makes a ‘sticky’ region that slows down (but doesn’t trap) the atoms. https://t.co/GfVJQMrPJm
To turn this into a trap we add a weak magnetic field that creates a force imbalance and a restoring force to the centre of the beams - a ‘magneto-optical trap’.
Here’s a photo of some of the lasers we use to cool potassium and rubidium - the optics on the table are used to distribute the light, precisely shift the frequencies of different beams, and shutter the light at different times in the experiment sequence. https://t.co/Qv0v7zvoPD
How do we cool atoms down? (Part 2 of 3)
There are a few laser cooling temperature limits. The Doppler limit is proportional to the linewidth of the atomic transition, and is related to to the random direction of photon emission when the atom de-excites (after absorbing the initial photon from the laser beam).
Fluctuations cause a random walk in the atom velocity and so limit the temperature. This limit varies a lot with atomic species - e.g. 146 μK for rubidium, but just 180 nK for strontium which has a very narrow linewidth transition.
The Doppler limit is an exciting chapter in cold atom history! In 1988 experiments showed temperatures much lower than those predicted by theory: https://t.co/GagJyLyoyQ. This turned out to be due to a more complex atomic energy level structure than was originally accounted for.
Work on laser cooling won the 1997 Nobel Physics prize: https://t.co/qsgexg1TeL.
Another temperature limit is the recoil limit, from the energy associated with the momentum kick of a single photon. This is determined by the mass of the atom and wavelength of the transition - e.g. 360 nK for rubidium-87.
This still isn’t the final limit though - various sub-recoil methods have also been developed, for example by preventing atoms from absorbing photons if their velocity falls below the recoil velocity.
How far the atoms are cooled with laser cooling methods depends on the atomic species, the goals of an experiment, and the choices and interests of the research group. Generally speaking, these methods get harder to implement the colder you want to go!
How do we cool atoms down? (Part 3 of 3)
Laser cooling is often followed by evaporative cooling. Evaporative cooling is pretty much the same process as the evaporation of your afternoon coffee! The highest-energy atoms leave the trap, and the remaining atoms rethermalise at a lower temperature.
The atoms are trapped using laser beams or magnetic fields (sometimes both!), and the higher-energy atoms are pushed out of the trap by lowering the trap walls or applying a field that drives them into an untrapped state. A lot of atoms are lost during this stage of cooling!
There are of course a lot of other methods, tricks, and details I haven’t mentioned! But this outlines the basic atom-cooling toolkit. If this all seems like a lot of effort, join me this evening to find out why we care about making our atoms ultracold!
The next few hours will be quiet from me because I’m teaching tutorials this afternoon (called ‘supervisions’ in Cambridge). Today we’re looking at magnetostatics! After atomic physics, I think electromagnetism is my favourite part of an undergrad physics course - what’s yours?
A lot of interesting things happen when you cool atoms to ultracold temperatures https://t.co/BacR3fSqcJ
The Heisenberg uncertainty principle tells us the position of an atom is spread out in space - the position uncertainty increases as you decrease kinetic energy. This is described by the de Broglie wavelength, which is inversely proportional to the square root of temperature.
At room temperature, the de Broglie wavelength is much smaller than the spacing between atoms, but as you cool the cloud this approaches the atom spacing. Atoms might now try to occupy the same quantum states - this is where atoms will behave in a way that depends on their spin.
Bosons (particles with integer spin) are able to occupy the same state - at some phase-space density (the number density multiplied by de Broglie wavelength cubed) the particles will fall into the ground state, acting like a single wavefunction - a Bose-Einstein condensate (BEC).
The BEC transition can be seen by looking at the atom momentum. We release the cloud from the trap and allow atoms to move freely for several ms, which maps their initial momentum into position.
A thermal cloud has a Gaussian distribution, but a BEC looks like an inverted parabola - you can see the BEC peak emerge as you go further in the evaporation process! Here's a gif of the BEC signal appearing as we evaporate (decreasing the power of an optical trap). https://t.co/4dhDCBLJkm
In contrast, fermions (particles with half-integer spin) are forbidden from occupying the same state by the Pauli exclusion principle. The atoms will instead fill the available energy levels sequentially, and become a degenerate Fermi gas.
Starting tomorrow we’re going to look at some applications of cold atom systems, starting with the example of building experimental simulations of complex quantum materials!
Unfortunately the gif I pasted into my last thread didn't work - here it is in the original post! https://t.co/v2feEx98k4
Every Tuesday morning the @CaMBQD group gets together for #JournalClub where we read a paper in advance and then discuss it. This week we’re looking at a paper by our PI @UlrichCamPhy so we’ll have the expert on hand! Why not read along with us? https://t.co/C9z75kOf1D
We can use #ColdAtoms to create experimental simulations of complicated systems. Today I’ll show you the first experiment that I worked on in Cambridge, building a quantum simulator for the physics of flat energy bands and frustrated magnetism!
The first step in building a cold atom quantum simulator is encoding the problem so that the behaviour of the cold atoms captures all the important characteristics.
For example, a lot of interesting materials have a periodic structure with a lattice of positively charged ions surrounded by a sea of negatively charged electrons. These lattices and the associated electron behaviour can produce some incredibly complex material properties!
This complex quantum behaviour can be difficult to directly measure or numerically simulate, so we construct an experimental simulation on a larger scale, using patterns of laser light to represent the lattice of the real material and ultracold atoms to represent the electrons.
This creates a very clean system that has the same or similar geometry to the real material, so that it captures the same physics. We can tune details like how tightly the atoms are held to a lattice site, the interactions between atoms, and can introduce noise or other features.
Because the cold atom system is on a larger scale than the real material (atoms representing electrons, and lattice sites separated by hundreds of nm instead of hundreds of pm) we can measure dynamics of the system at a single-site level using atom fluorescence and a good camera.
These experimental models are therefore tuneable, easy* to measure, and capture the quantum properties of the real material. This means we can use them to get additional insight into the properties and behaviour of the systems we're modelling *relatively easy
Tune back in over lunchtime to see just how we use laser light to create the structure of the quantum simulator! https://t.co/W4gUqh2nB5
Yesterday we saw that laser light can be used to cool atoms. Because a light field affects the atom's energy levels, lasers can also be used to trap them!
If the wavelength of the light is longer than the atomic energy transition (“red detuned”) the atom is attracted to high intensities. If it is shorter (“blue detuned”) the atom is repelled.
So if we can make patterns of light with a geometry that captures the physics we’re interested in simulating, we can use this to trap the atoms and create our simulator!
A popular method of creating patterned light is to use the interference between overlapping waves. You’ve seen this effect before - think of the patterns that form when two ripples overlap on a lake or pond!
The same thing happens with light - when the waves overlap they add together, creating variations in intensity with a length scale smaller than the laser wavelength (hundreds of nm). By shining laser beams with a certain geometry we can create a huge range of patterns!
Here’s an illustration from my research group @CaMBQD - laser beams (blue) are reflected from mirrors (circles). Where each beam overlaps with its reflection, interference creates a pancake-like structure. Where beam pairs overlap we get a 3D cube of high/low intensity. https://t.co/alcGiNOJ66
Here’s another example from my research group (I don’t work on this experiment) - four laser beams (blue arrows) are reflected from mirrors (grey circles). This particular symmetry creates a quasicrystal instead of a periodic structure.  Image credit: Dr Ed Carter (PhD thesis) https://t.co/7ACSAAzeUI
Learn more about quasicrystals here: https://t.co/Nzet1hUCA1
We also have an experiment studying the kagome lattice (this is the experiment I started building when I first moved to Cambridge). The kagome lattice is the pattern of triangles pictured below. https://t.co/aeaU7YiQya
We need two laser wavelengths to create the kagome lattice! A blue detuned interference pattern (short wavelength, atoms repelled from high intensity) is overlapped with a red detuned pattern (long wavelength, atoms attracted to high intensity).
This is shown here - arrows represent the laser beams (no reflection this time!) and where these arrows overlap I’ve shown the spatial variation in atomic energy levels - atoms are trapped by purple and pushed away from yellow. Adding the lattices creates the kagome structure. https://t.co/AoglB1N4eP
More about the interesting physics of the kagome lattice later today!
One interesting property of the kagome lattice is geometric frustration where particles that want to align with their spins (arrows) opposite the spin of their neighbours find that they can’t - quantum simulation is one approach to working out how these systems behave. https://t.co/ARM3sB69zK
The (calculated) energy structure of the kagome lattice is pictured here (energy on the y axis) - one feature here is a flat energy band, where particles should behave as though strongly correlated and infinitely heavy. We want to study this flat band physics! https://t.co/F9EdT0bxI3
The kagome lattice exists in solid state systems too - see e.g. https://t.co/CtENOj8rqH and https://t.co/HbSewzXVRM
A quantum simulator can give tremendous insight into the physics of a complicated system - however I think it's important that we acknowledge both the power and limitations of the technique, and keep talking to scientists tackling similar problems using different methods!
Join me later for a virtual lab tour to see how these different ideas come together to create a real quantum simulator!
Time for a lab tour!
The kagome lab uses rubidium (bosons) and potassium (bosons and fermions). We prepare all the light for laser cooling, optical trapping and optical lattices on two big optical tables, and our vacuum system sits on a third. Here are our laser tables: https://t.co/OnolDfz0zX
This is a CAD model of our vacuum system - atoms are cooled from left to right in the system following the methods described yesterday (see posts below) https://t.co/7M0WSVPsMz
The ampoules of potassium and rubidium sit in the bellows labelled ’source’ and atoms diffuse into the rectangular chambers above. These are our 2D magneto-optical traps (MOTs) - the first stage of laser cooling.
A beam of laser cooled atoms is pushed into the 3D MOT, where we continue laser cooling. The atoms fluoresce - here’s a photograph of a brightly-glowing cloud of laser-cooled rubidium (a few tens of million atoms, at around 200 μK). In reality this is a beautiful red colour! https://t.co/nMQEaTICIV
We turn up a strong magnetic field and a laser beam (together making a ‘hybrid’ trap) to trap our atoms for evaporative cooling. We load atoms at a few μK into a focussed laser beam and use lenses with a tuneable focal length to transport the atoms 50 cm into our science chamber.
In the science chamber we can evaporate the atoms further, by lowering the depth of an optical trap made of crossed laser beams, and then load into our optical lattice. Our lattice lasers only arrived a few weeks ago so this is still a work in progress!
We also have the label for ‘DMD’ potential - this is a plan for the future, where we will project additional laser patterns onto the lattice using a programmable micromirror array.
The ‘quantum gas microscope’ is for single lattice site imaging. We will make the lattice very deep (to hold the atoms in place) and then simultaneously laser cool the atoms and gather their fluorescence using an objective lens inside the vacuum chamber.
Putting the objective in the vacuum system was daunting - the objective had to be perfectly aligned to the lower viewport. Fortunately we measured this carefully before pumping out our vacuum - the first time we put it in there was a slight tilt! Second time worked perfectly😅
Here’s a photo of PhD student Dan carefully placing the objective lens inside our vacuum system - and the same chamber once sealed and surrounded by coils and optics! https://t.co/T94E3mSxW4
We can get complementary information about the cold atom system by dropping the atoms as I described yesterday - releasing them from the trap and letting them fall freely will give us useful information about their momentum.
A cold atom quantum simulator takes a long time to build! Over the last four years we've turned an empty lab into a working cold atom apparatus and are currently making the last refinements to turn this into a fully operational quantum simulator.
We have plenty of experiments planned out, so the next few years will be filled with data analysis and exciting results!
One of my favourite things about being an experimentalist is that you get to think and learn about both the practical aspects of building an apparatus and the exciting physics that the experiment is used to study!
All experiments are a team effort! The current kagome team is PI Ulrich Schneider @UlrichCamPhy, postdocs Tiffany Harte (me!) and Mehedi Hasan @mhasan137, and students Dan Reed @danreedphysics, Max Melchner, Luca Donini @lucad_96, Sompob Shanokprasith and Dan Braun.
Today I've been getting things ready for us to start assembling the vacuum chambers for our new experiment where we'll use #ColdAtoms to detect #DarkMatter and #GravitationalWaves! More details about that coming tomorrow!
[admin] "Creating New Quantum Materials Atom by Atom" Extended conversation with the amazing @UltracoldTiff is out now 👇🎙️🎧 #UnderTheMicroscope #SciencePodcast https://t.co/xc14oBS5ma
Yesterday I talked about using #ColdAtoms trapped in laser light patterns to build experimental simulations of quantum materials. Today let’s look at a different application of similar techniques: atom interferometry to detect #DarkMatter and #GravitationalWaves.
Interferometry is commonly seen using light. Here is a sketch of a Mach-Zehnder interferometer, where a laser beam is split in two then recombined, and the signal detected by photodiodes (grey semicircles) reveals any difference in phase between the two branches. https://t.co/jUmPOpmsaO
Atom interferometry is exactly the same idea, but using clouds of cold atoms instead of light! Lasers (yes, lasers again!) can drive transitions between atomic states. This can either create a superposition of states (a ‘beamsplitter’) or completely switch states (a ‘mirror’).
Here’s a Mach-Zehnder interferometer for atoms (straight lines): blue is the ground state, and dashed purple the excited state. Grey wavy lines are the laser pulses that act as mirror and beamsplitters. https://t.co/Rss13zu89d
The ground and excited states have different momenta, so travel along different trajectories. Any difference in phase that these clouds accumulate can be inferred from the interference pattern obtained after the final ‘beamsplitter’ laser pulse recombines the clouds.
The atom interferometer is therefore sensitive to anything that might change the phase evolution between the two branches - tune back in at lunchtime to see how this relates to dark matter and gravitational waves!
I’m currently working in a new consortium called AION (Atom Interferometry Observatory and Network) which plans to build cold atom detectors to test ideas about fundamental physics and complement traditional technologies such as LIGO.
We will operate two interferometers in parallel, separated by a very long distance - 1 km separation is planned for the final terrestrial detector, and then we plan to put the interferometers into space! The detector will look like this: (Image https://t.co/KAFNOhmgzI ) https://t.co/lsLAWpRky3
Each 'atom source' is a cold atom cloud that we launch in an interferometry sequence. The red shading represents the laser beams used to create the beamsplitter and mirror interactions.
We will make a differential measurement between the two separate cold atom interferometers, and will be sensitive to any differences between them.
For example, a gravitational wave will stretch and compress space-time. This will change the amount of time that it takes laser light to travel between the two interferometers - we will detect this as a time-varying difference in the interferometer phase.
We will be sensitive to mid-frequency gravitational waves (tens of mHz to a few Hz) which will complement the sensitivity of LIGO (tens of Hz to kHz) and the planned LISA detector (below Hz) - this means we can get information about different stages in e.g. black hole mergers.
Dark matter is a very different detection problem because it’s still such a mystery! An atom interferometer will be sensitive to the predicted couplings of dark matter models to standard model fields, and so can be used to either detect or exclude certain interactions.
e.g. ultra-light scalar dark matter is predicted to be an oscillating field that will change the electron mass and fine structure constant. This will change the atomic transition frequency and so the phase evolution that we can detect in the differential measurement.
A longer separation between interferometers will give a greater sensitivity but will also have technical challenges - space missions and even a 1 km terrestrial detector are still decades in the future! This afternoon I’ll describe the work we’re doing now towards this goal.
I got caught up in work this afternoon so forgot to post! A very long thread is incoming…
Over the next 2-3 years, we'll develop technologies that will make the large-scale AION detectors possible. There are 5 cold atom research groups, each with our own apparatus so that we can research in parallel and then combine all the techniques in a single prototype.
This project is a new way of working for me! In cold atoms we typically work in small groups to build and operate an experiment. Here we’re working extremely closely with the other experimental teams - it’s more like being in one big research group spread across multiple sites!
This level of collaboration means a lot of meetings, and disagreements about the best way to build an experiment! But it’s also a great way to spread the workload and have access to expertise in different areas. It’s also a great chance to work with and learn from more people!
Right now we’re working on preparing a suitably cold cloud to use in the interferometer - our final target is less than 1 nK! There are also teams looking at improving sensitivity, such as by increasing the separation between the interferometer arms with repeated laser pulses.
The colder the cloud, the less it will spread out and so the longer the possible duration of the interferometry sequence - this increases the detector sensitivity.
A compact cloud also means the atoms should all see a more uniform laser intensity, improving the fidelity of the interactions between atoms and light.
We’re going to start assembling our vacuum system in the next few weeks, and this is what it will look like: (description below) https://t.co/3fdhCPbklI
Like the apparatus I showed you yesterday we start with laser cooling in a 2D magneto-optical trap (MOT) (see Monday’s thread on laser cooling) to create a pre-cooled beam for laser cooling in a 3D MOT.
We will then trap in a laser beam to evaporatively cool the atoms and transport them by moving the laser beam focus into a test chamber for interferometry.
This final chamber isn’t the long tower that we’ll be working with in future years! We’ll develop the technologies on an apparatus that fits nicely on an optical table, then transfer the upgraded cold atom source (everything up to and including transport) onto the final detector.
We’re using ultracold strontium atoms - I’ve previously only worked with rubidium and potassium (group 1) so it’s exciting to be working with a group 2 element!
Strontium has an energy transition with an extremely narrow linewidth (mHz) and a correspondingly long-lived state - this is called a clock transition because it's very useful for keeping time! https://t.co/oNJAyJfUoz
This narrow clock transition allows us to use a single-photon instead of two-photon process for our mirrors and beamsplitters, eliminating laser noise in the differential measurement and allowing us to use a large separation between the interferometers (increasing sensitivity).
The Cambridge team is working on the techniques to cool and transport the atom cloud, to provide the best possible starting point for interferometry. Our goal is to provide atom clouds with as many atoms as possible, as cold as possible, and produced as fast as possible!
This includes the methods I’ve discussed previously, as well as tricks like using carefully controlled laser pulses to act like lenses to collimate or focus the cloud as it travels (https://t.co/OGM3SZxfu0).
The project started in May, and we've spent the last few months designing the apparatus, working on calculations, and setting up the lab. We’ve also been testing some optical transport techniques so that we can transport the atoms with as little heating or atom loss as possible.
We’re at an exciting time for the experiment, getting the vacuum chambers assembled and filling our tables with laser cooling optics! We’ll be spending some time tomorrow tidying the lab and making space for deliveries - an experimentalist’s job isn’t always glamorous!
Once again this is of course a team effort! The current (Cambridge) AION team is PI Ulrich Schneider, postdocs Tiffany Harte (me!) and Kimberly Tkalčec, and students Xintong Su, Michael Hsu, Brian Bostwick and Zach Eyler. The full AION collaboration list is very long!
Tomorrow I’m going to change direction and talk more about myself, and how and why I became a physicist. Since we're approaching the end of my week here, let me know if there are any other aspects of my experiments you'd like to hear about!
I became interested in #Physics as a teenager because I loved reading fantasy books 📚 The one that influenced me the most was Philip Pullman's #HisDarkMaterials which has lots of science ideas woven through it, including atoms and dark matter, parallel universes and more!
I started reading about the science behind all this and knew I had to keep learning more! Chemistry was my favourite subject at school but I knew early on that I wanted to study physics at university, and that I wanted to be a scientist working on 'magic' in real life!
Are there any books or authors that changed the way you see the world, or that you think influenced your life choices?
@Felgraf_Physics Yes! His books are incredible, I wish I'd started reading them earlier. Although at least that means that there are still plenty that I can still enjoy for the first time now!
I studied undergraduate physics at the University of St Andrews in Scotland and loved the physics department @PhysAstroStAnd. The department clearly cared about teaching, and the academics were always so supportive and welcoming of questions.
Students were encouraged to do (paid!) research projects over the summer, and this was a fantastic way of integrating undergraduates with the research activities in the department. As a student it was great to get experience of research before committing to a PhD.
I had two amazing summer projects - one in cold atoms @UltracoldStAnd and one on scanning tunnelling microscopy in the predecessor of @Kinggroup_ARPES. The research groups were incredibly welcoming and supportive of students making mistakes and finding their feet in the lab!
It was then that I fell in love with cold atoms 😍 The experimental techniques are fun and varied, and the underlying physics and experiment goals seemed incredible. When I first stepped into the cold atom lab it felt like I'd finally found the magic I'd been looking for!
I was lucky enough to be working on a really fun project - designing holograms to use as traps for ultracold atoms, supervised by then-PhD student @grahamdbruce.
This used a spatial light modulator, a programmable liquid crystal array that imprints a phase pattern on a laser beam (by slowing down different parts of the beam). After some simple optics this phase pattern creates intensity variations, making an interesting optical trap!
I continued working on this for my MPhys research (the final year project for an integrated undergraduate masters), and developed a flexible approach to calculating the phase patterns based on cost function minimisation (https://t.co/aU5azvl1LJ)
The research (and team) was so much fun that I continued some work with them after I'd left - extending the holographic trapping work and applying the methods to a completely different (theory) problem with @PhysicsSteve (https://t.co/fnMqyPLstd, https://t.co/sgE9gfo4XY)
I feel so lucky to have had such an amazing undergraduate experience! I'm incredibly grateful to all my lecturers and tutors, especially those who patiently answered my long lists of questions - I now have a better appreciation for how busy they must have been!
During one of my summer projects I read a paper about creating vortices by rotating a cold atom cloud, a branch of quantum simulation that uses parallels between the forces on rotating neutral atoms and charged particles in a magnetic field. https://t.co/IHPYdYQIrF
I knew at that stage that I wanted to do a PhD, and was pretty certain I wanted to continue with cold atoms, so I applied to (and was accepted by) the cold atom group at the University of Oxford who had written that paper.
(This is a compressed version of that story! I applied to several research groups, who all do incredibly exciting work. I definitely recommend students explore their options and apply to (and visit) several groups to work out what research and group dynamic works for them.)
My PhD research was on radiofrequency-dressed magnetic traps for ultracold atoms. These are magnetic traps with a radiofrequency field applied to create a trapping surface where the atomic energy level splitting due to the magnetic field is resonant with this frequency.
For us this created tuneable ellipsoidal trapping surfaces, and my main PhD result was the first experimental demonstration of using several radiofrequency fields to create concentric trapping surfaces for quantum simulation or atom interferometry. https://t.co/Hmrz9fKemQ
I also continued working on shaped optical traps - this time using the deflection of a laser beam by acousto-optic devices (where an acoustic wave in a crystal creates a diffraction grating) to rapidly ‘paint’ and also create precisely-controllable arrays of individual beams.
I quickly felt overwhelmed when I started my PhD. I had expected a steep learning curve, but I wasn’t prepared for such a ‘sink or swim’ environment.
I’m sure this works well for some people, and there can be a lot of value in being given the independence to try things out for yourself and make mistakes - but I think this should be balanced with enough guidance and support for each student to thrive.
However, this PhD experience gave me the confidence of knowing that I could learn to understand, build and fix a complicated system. I also learnt a lot of interesting physics, and good science practice along the way!
I was also fortunate to share most of my PhD years with the best possible lab-mate, @drbentine, and other fantastic students. I learnt the value of teamwork in facing challenges that would be much more difficult alone!
I finished my PhD knowing that I wanted new challenges, but also that I wanted to continue working in cold atoms. That's why I was so excited to start a postdoc building a new experiment and working on optical lattices!
I started my postdoc at @Cambridge_Uni @DeptofPhysics four years ago, and have grown a lot as a researcher both inside and outside the lab. I’ve talked a lot about my research over the last couple of days, so this will be a short thread about some of the other things I do.
I’ve been lucky enough to belong to a college while here - first @JesusCollegeCam and now @Kings_College. College membership is a nice way to stay connected with the broader life of the university. There’s a great community and opportunities to learn about interesting research!
Through college I was able to start running some of my own public outreach and engagement events. I love running workshops for primary school children and seeing their enthusiasm for science! I’m also really excited about an upcoming game exploring quasicrystals and 4d space!
I’m co-chair (with the amazing @beth_tennyson) of the department Research Staff Committee, where we represent postdocs in the wider department, and build a community for research staff.
We’ve been organising discussions and social events exploring ethics in physics research. I think that researchers should be aware of the impact of their work, and some study of ethics could be a useful part of researcher training.
It’s very easy to become single-minded about your research but I think I’m a much better scientist (and a happier human) when I make time to pursue other projects and interests!
I’m not sure what my career holds next. I'm enjoying my current research and am trying to learn more about funding processes. I have a few applications currently in progress so hopefully the next few months will bring good news!
This will be my last day on this account - I’m following my own advice and taking the weekend off from anything remotely adjacent to work! Today I will talk about some of the practical side of working with cold atoms, and offer some advice for people interested in the field.
One of the things I love about our experiments is that we tend to work in small teams building our own apparatus, so you have to be familiar with every part of the experiment.
(This is less true of my new interferometry research, where a huge team will be involved in building the full-size detector. Being less directly involved in various aspects of the experiment and apparatus is something I’ll have to get used to!)
This means understanding an experiment timing system that will control laser powers and frequencies, shutter light, and control magnetic field sweeps - all at μs precision or better. This includes both hardware and the software that controls it.
You will spend a lot of your time working with optics and lasers - optics alignment can get competitive! You will work on ultra-high vacuum systems if you’re building or extending an apparatus. There are always small (or large) electronics tasks so you’ll be good at soldering!
You will also do a lot of computational simulation and modelling to explore ideas for new experiments and help inform design choices. Once an experiment is running you'll need to be able to analyse and understand the results.
Disclaimer - this is a list based on my own experiences! Different research groups operate differently, and there will be an emphasis on certain tasks more than others at various stages of an experiment’s lifetime.
This means there are always opportunities to develop new skills! Absolutely no-one enters the field with all those skills already, and joining a new research group is a learning curve even if you’ve already worked on similar experiments before.
You’re unlikely to enjoy every part of the work - e.g. I really don’t enjoy machining parts so am glad now that I can delegate those jobs! Everyone has natural strengths and interests that they will gravitate towards in finding their niche in the team.
And let’s not forget the other important research skills - teamwork, communication, problem-solving, planning, and time-management. As you progress in your career, leadership and management. These are so often overlooked but research would fall apart without them!
I think that the most important skills I’ve developed during my career have been general problem solving: being able to take a complicated problem or system and work out how to methodically break it down into solvable parts.
Thread on my advice if you’re a student interested in a cold atom PhD, or a PhD or postdoc looking for a change in direction - bear in mind that this is based just on my own experiences and opinions!
It’s worth thinking about what skills you want to develop and where your interests are. e.g. are you more interested in thinking about physics goals and analysing data from an experiment that’s already running, or would you like to be part of the design and engineering process?
Try to align this with your long-term goals (with the understanding that these might change!) - e.g. if you want to run your own group one day it’s a good idea to get some experience of building an experiment.
But also consider that this will affect your publications - unfortunately these matter! A brand new apparatus might take 3 or more years before you start seeing high-impact papers, so weigh this against the skills you’ll develop during the building stage.
That is something I should have considered more seriously! If you are at the start of the building process make sure that your funding covers long enough to have a reasonable chance of publications, and discuss the option of publishable side-projects with the PI.
Think about how your previous experience and existing skills fit in with the type of work you’d be doing. A lack of direct experience shouldn’t prevent you from joining an experiment (in my opinion) but think about how your existing skills and interests can be expanded.
Personally I’m always happy to be contacted by prospective students by email, but we can have a much more constructive conversation if you show that you’ve looked into our research and have a general idea about the kinds of work this would involve.
Try to visit a research group and speak with the current students and postdocs. Don’t be afraid to ask awkward questions to check it would be a good fit for your specific needs and goals. If you want to spend time on e.g. outreach or teaching, make sure the PI would be on board.
I mentioned this yesterday, but invest time in developing other skills and interests - this makes you a happier person, increases your skills, exposes you to different career options, and can end up increasing your motivation for your research!
Finally: the experiment will always be there. Don’t be afraid to go on holiday, spend time with friends or family, or take weekends off - sometimes an emergency or set of measurement will require long hours but this shouldn’t become your standard way of working!
That’s all from me - I hope you’ve enjoyed hearing about my work and the world of the ultracold this week. Thanks so much to the RealSci_Nano team for having me, and follow me @UltracoldTiff for more updates! https://t.co/54mKV3xNsA
[admin] Huge thank you to Tiffany (@UltracoldTiff ) for a wonderful week of science, do give her a follow! Podcasts ft. Tiffany are here - Short - https://t.co/WqpmdBz6Oe Long - https://t.co/xc14oBS5ma #UnderTheMicroscope #SciencePodcast https://t.co/TnpB32SN8B
Hortense Le Ferrand
[admin] "Nature Inspired Additive Manufacturing" Please welcome @HortenseLeFerra for a week full of amazing materials/nano science! ✨ Listen to the podcast to know what is coming your way this week 👇🎙️🎧 #UnderTheMicroscope #SciencePodcast https://t.co/HNwSESopWw
Good morning! My name is Hortense and I am delighted to spend the week twitting about bioinspiration, microstructured composites, and additive manufacturing. Picture of the day: what do you think these electron micrographs show? Tell me what you think! https://t.co/N1K7pRDMrR
So, I have 10 minutes gap before my next Zoom meeting... so here is a hint! https://t.co/UJvcBYWsVn
I was looking for other pretty pictures: check out this link on borepanda! So.... why on earth am I posting about snails 🤔😜? https://t.co/0XV5ha1WZB
Talking about snails, I just opened my Twitter and look what I find: a paper on soft grippers showing a hand grabbing a snail! That's proof how snails can be inspirating! https://t.co/6HjCo8bLk0 @SciRobotics https://t.co/4s9QwOPpni
So, time to get the answer.... the electron images shown earlier come from the shell of two snails species. Why are they interesting? because if you at it carefully, you can see some structure in it. This structure comes from microparticles oriented in specific directions...
Yes: the shells of snails are microstructured composites: particles in a matrix with a specific orientation. Now, why are they so? probably because this makes the shell strong, and protective, while remaining lightweight. Microstructured composites have unusual properties!
Also, these 2 shells comes from very funny snails, provided by my colleague Yuta Morii from Kyoto University https://t.co/UDrgjwDY1w. Yuta is a zoologist studying species. Those 2 snails come from Hokkaido, and have different defense mechanisms...
The first one retracts in its shell... while the other snail swings its shell like a club to scare predators!! Check out the paper and the supplemental material for the video: https://t.co/cxG7JDev3W https://t.co/VxwDYDqrLs
One striking particularity here, from a biologist point of view, is that both snails live at the same place and have almost the same genome, yet they have very different pheonotypes. So, looking closely at the microstructure-properties of the shells was interesting. ...
interesting to understand the constraints of the environment and how it leads to this 2 evolutionary paths. The conclusions are that there might be an evolution driven by predator-prey interactions... and that it can bring some bioinspired ideas.
Check out here if you are interested in some more reading: https://t.co/l0hn0KCpbr
Also, I grew up in Burgundy in France, where people eat snails :,( https://t.co/Kr9fNT4wTN but I feel close to the animal! I am very proud of this small study! https://t.co/5AXXEauh52 https://t.co/pmJh7KZBDH
snails are anyways fascinating: apparently, their patterns influence their personalities! https://t.co/fQCNsNQm0q Anyways, we made the connection between nature and microstructure, next I will introduce how microstructure and additive manufacturing come together!
To conclude today's thread on snails, I hope to see your pictures of snails here 📸⬇️. This is the last one I took here in Singapore, a couple of days ago. Indeed, I am now based Singapore at the Nanyang Technological University. Singapore has 32 land snails species. https://t.co/Sr8GRlgglA
Hi, today we'll be discussing another type of shell: that from seashells! Specifically, the colorful part of the shell that is made of nacre and that is inspiring many development in materials because it is ceramic that is very difficult to break! ( https://t.co/5LGBsJLFtE) https://t.co/JeFKd6A6Vs
see how it is difficult to drill into a seashell! https://t.co/ekMwK0jXKp
But, hey, can we make artificial nacre?
I know you have been anxious to hear the answer. Luckily it is break time and it is raining outside so it will be a break-twitter time... and the answer is yes! there are multiple ways to process and recreate nacre. Some use the same materials as the natural seashell...
And they also look the same! Look at these ones here, made of calicum carbone grown in a layer-by-layer fashion : https://t.co/NuDYgejyUV. The reason for the iridescence comes for the nanometric thickness of the layers. These are call structural colors. https://t.co/Za2jC4vUg0
There are many other ways to create colours simply by the microstructure. But this is another field of bioinspiration and we are slightly diverging from the initial tracks... (but it s cool so check out the picture below) https://t.co/kQIwHsyq85
So back to artificial nacre. Other methods use artificial materials to make artificial nacre, for example graphene, or aluminum oxide or boron nitride. This is interesting, because the properties are lot better than the natural material! https://t.co/SvJfrs9wTn
In my group, we use magnetic fields to process our nacre-like composites and turn them into porous ceramics.https://t.co/P15VueARBF But the truth is that we are developing 3D printing of such material (so make sure to ask me again in a couple of years!)
Some of the most recent development on nacre-like ceramics are, I believe, the impact tests!! check out this paper for impressive images of the resistance of the ceramic tiles: top are normal ones, bottom are the nacre like! https://t.co/VrcXTgMjmG https://t.co/r9GzN2JOtI
And I don't mention that the principle can also be applied to transparent ceramics and others! check out the video to see researchers trying to break those materials https://t.co/mx84yAvKbv
But personally, I am also excited at the idea of using nacre-like composites in biomedical applications. Did you know that nacre was used as tooth replacement by the Mayas? Probably not only because it is pretty... https://t.co/hKRCqQFFNk
So, now we have made the connection nature -> microstructured composites -> manufacturing -> applications. Still a lot of research questions to address yet!
Better than Netflix! To discover more about bioinspiration, how researchers end up there and what are some future challenges and directions -> I recommend the conversations from University of Melbourne at this link: https://t.co/blA9dIIMEd
Beware: nacre glass italia coffee table is not made of artificial strong and tough nacre :) https://t.co/hjr4rj0tqq
Hello! after snail shells and seashells to day we will talk about getting inspired from plant to create self-shaping materials. Plants, like other natural materials, also has a microstructure. In this case, it is cellulose fibers that create the microstructure. https://t.co/GaDfcMOr6Z
How do carnivorous plants close? Can we create artificial composites that can do the same? Why would we want to do that and what for? stay tuned... https://t.co/0DGN09nDdD
[admin] "Nature Inspired Additive Manufacturing" Extended conversation with the amazing @HortenseLeFerra is out now. ✨ Give it a listen! 👇🎙️🎧 #UnderTheMicroscope #SciencePodcast https://t.co/T7ZWikIRQV
Thank you for waiting! So, the morphing from carnivorous plants is complex, but can be simplified by the principle of bistability. Each leaf of the trap can be schematized as a bilayer composite with perpendicular fibers. https://t.co/aEoT0WaS7L
Due to the perpendicular orientation of the fibers, stresses are stored in the structure, leading to 2 stable states of the bilayers, and a fast snapping from one state to the other, exactly like snap bracelets. https://t.co/lVyIlntYdH https://t.co/J1Qv285JKh
With this principle, artificial flytraps have been made using carbon reinforced composites: https://t.co/NnUcR1wEC5 https://t.co/j0osnPRxfd
In the past, my colleagues and I also created some samples using small microparticles oriented with external fields. https://t.co/853ttIMAbO https://t.co/DD58uxmdX5
But there are many other super interesting sensors and robotic devices that are inspired from the Venus flytrap. Some can be light-actuated, temperature actuated, magnetically actuated, touch-actuated, etc. example of the light one here: https://t.co/dj3A1CMbCR https://t.co/v0miuTeIxU
What is really cool with these bioinspired materials, is that they open a lot of applications for autonomous, self-adapting structures. I believe one day we will make robots that sense and adapt to their environment thanks to these materials https://t.co/q0hYGvhXOi
But they also open a lot of applications for architectures and building. Imagine: closing and opening of windows, shades, roofs, ... without the need for electricity or other energy. This can be used for passive cooling, for example. https://t.co/TtuRaThzMf
Leading research in this area is lead by LiVmats in Freiburg, Germany. They use expertise from plant biologists, engineers, and architects to create, for real!, large scale autonomous structures. https://t.co/2Rf7vgLT8Y
What we are excited with in my group is the diversity in shapes we can get, while having the fast morphing, and how we can use 'smart' building blocks inside the material to embed intelligence. This is the field of robotic materials! https://t.co/OdvgJ3r0ZK
Bonus: grow your Venus plants! Distilled water diet to have it develop tricks to trap insects! https://t.co/jdnd7Sdzym
and a very cool example of electronics using Venus Flytrap! https://t.co/qKXoFV2TR6 https://t.co/uf3XBq9BOm
Good morning! today's thread will talk about big eyes, hammers and exoskeletons! https://t.co/FiLYmUlfG9
https://t.co/IGkFYbhoj3
With regards to yesterday's topic on self-shaping, smart intelligent materials, etc, I invite you to check out this webpage from a research group in CMU: they have very nice demonstrators! https://t.co/95UD9CuKqy
Yes, that is a Mantis Shrimp! Apparently, you can get it from the supermarket to have a closer look. At first, I was surprised by how big they are: around 15-20 cm long! there are different types of Mantis shrimps, but will not go into the details here. https://t.co/45lO3ue8IX
There are many parts interesting in the shrimp. Where to start? The dactyl pod, first, is like a ceramic hammer that is strong, tough, and impact resistant, and can even break seashells (including nacre, have a look at the thread 2 days ago) https://t.co/YjjLnNrraw
This performance is largely due to its special, helicoidal type of microstructure, called Bouligand from the French mathematician Yves Bouligand who described the structure. Bouligand structures remind the cholesteric arrangements of liquid crystals. https://t.co/jf0rnR3gbw
One other interesting part of the mantis shrimp is the saddle in the arm. Basically it stores energy before releasing it very quickly, like an arbalet: https://t.co/Kh675skKd8 https://t.co/qWEkYp6Unz
The telson, or 'tail' of the shrimp, has also a shape and microstructure design to help the Shrimp absorb energy. Check out this 1 min video that explains it: https://t.co/1KuK67jVdW
And can we talk about the Mantis shrimp without talking about its vision? Its eyes can rotate, and they can see polarized light. I'm not too too familiar with these optics, but you can check out this paper: https://t.co/l2gtnrk0Wm
Finally, what is also pretty cool for the Shrimp is that it is has a chitin, like beetles or cockroaches. Chitin is a hydrophobic, tightly crosslinked hydrogel that can be used for sustainable materials like packaging and many others applications! https://t.co/fKBzt4ZQGI
Recently, one of my colleague @NTUsg used derivatives of chitin for green hydrogen generation! Instead of chitin, the material used was chitosan, basically a hydrophobic version of chitin that is more easily processable. https://t.co/8OwEheQW6H
Mantis shrimp is a source of many bioinspired materials. Material researchers are exploiting similar helicoidal microstructure to increase the mechanical properties... using cellulose nanocrystals or even cement!
At NTU, the Mantis shrimp expert to talk to is : https://t.co/fy3FTkDtop There is even an aquarium in the lab, so that it is possible to study the evolution of the shrimp growth and molting. This led to understanding of the formation of the shrimp, which is like die casting.
Another Mantis expert is in California, looking at the natural material and its bioinspired counterparts: https://t.co/aezPwDsyaZ
Another one is the Patek lab at Duke. Check out this link for the sounds that make a variety of Shrimps! It is only a few sec:) https://t.co/gP2avYILTj
I apologize for not naming all the other groups working on the Mantis, but anyone working on it, closely or remotely, please post: looking forward to hear from you!
@DevilleSy and you have no idea how hungry they are in the morning! I use to shake a plastic piece in front of them in the aquarium of Prof Ali in the mornings, for fun. They were already striking into it!
Hi, today's microstructures.. that of bone! Here from the cuttlefish. You will note that B and E looks very similar to the Bouligand structure we talked about yesterday... from -> https://t.co/0liwEQvXZV https://t.co/btvdAXTVRa
Here microstructure of teeth, from -> https://t.co/elCGHgNqd2 https://t.co/d0wO1WdqFT
and from human porous bone: https://t.co/eLUbLJgWDG
As a comparison, artificial bone implants look slightly different, like this wood pile structures (3D printed) https://t.co/k4mTtoktI3
Or foam-like, such as this one: https://t.co/6KYyHEvO0V
@i2m_dumas Beautiful! If I am correct the 'chambers' give the cuttlebone strength and toughness despite being a foam, as well as some function for the buoyancy of the animal: a truly mutlifunctional material!
Bones are diverse and intriguing. They are also a living materials that constantly decays and grows, has nerves, blood supply, and is storing mineral on top of the mechanics. With @christos_edward we put some thoughts into it, from a materials perspective: https://t.co/KxliBaQP8H
There is a growing community that tries to reproduce the microstructure and composition of bone for biomedicine. Even in Tissue Engineering, bioinspiration helps in growing more 'natural' bones. Check out this lab, for bioinspired constructs: https://t.co/XGc5LWuVFa
To get an quick overview of a field, I like to use Google image. (That's a tip from @FlorianBouville :) ) I invite you to type in 'Bioinspired Bone' in google image to see the diversity -and large- research output in the field.
Even BBC is talking about bones -> what is the smallest bone in our body? Check out the video https://t.co/eJH4rkNPjz
I hope to share soon about nice work done in my group where we use 3d printing to try to emulate the microstructure of bones in ceramics... stay tuned! The Phd student working on this topic will present at this new, yet very select, conference! https://t.co/YfKRxy5ERY
Just as I am twitting I am wondering if anyone has done bioinspired cochlea implants... looks like it has a research potential. But the key for biomedical-oriented research is also to get input from the medical doctors and surgeons!
So it is Friday evening (at least for me) so I have been searching for a song by typing 'bone' in Youtube. The closest I got is one of my favorite dancing song from bone....y. Perfect to end the hectic working week! https://t.co/2b0Fo3xn5R 🤣
Dear all, this end of the week is the end of my role as curator for this channel. It was really fun and I am looking out for who's coming next week! To keep in touch, I am at @HortenseLeFerra. My lab website is at https://t.co/ygREmFDjZm
I also like to about what we do in the lab (Tales of the lab series) and other random stuff there: https://t.co/h9tHdzOMrx. Pretty pictures, dancing music, crazy ideas -> hope to see about these on twitter or other media! Cheers.
[admin] Thank you @HortenseLeFerra for a wonderful week of science!👏 Do give her a follow! ✨ Podcasts ft. Hortense are 👇 Short - https://t.co/HNwSESopWw Long - https://t.co/T7ZWikIRQV #UnderTheMicroscope #SciencePodcast https://t.co/c69xbektuy
Burak Guzelturk
[admin] "Dancing Atoms and the Stories they Tell" Please welcome @BGuzelturk for an amazing week of materials/nano science! ✨ Listen to the podcast to know what is coming your way this week 🎧🎙️👇 - https://t.co/SP5xq9sAYf #UnderTheMicroscope #SciencePodcast
Hello Materials/NanoScience Enthusiasts! My name is Burak Guzelturk. I’m excited to share my journey in science this week. Before kicking in with exciting ultrafast X-ray science - big applause to organizers of this account for bringing wider voice to scientists around the world!
A little intro about me: I am a beamline scientist at Advanced Photon Source, a synchrotron part of Argonne National Laboratory. In our beamline, we are doing time-resolved X-ray scattering and spectroscopy experiments on a wide range of material systems.
We are shooting lasers and X-rays onto the samples at the same time and watching how atoms jiggle and wiggle due to excitation, how they interact and relax over time. https://t.co/bQ6sw8po0W
You will hear some of the recent exciting stuff using such ultrafast structural measurement techniques throughout this week, how useful they are... Also tips and tricks on how to get beamtimes at large user facilities, prepare for beamtimes and hopefully get successful results! https://t.co/5t5p1TBoPi
Alright, let's get into business of ultrafast X-rays!
Synchrotrons (and XFELs) are basically giant machines acting as X-ray lasers! https://t.co/4TbCYgS5fg
These places provide pulsed X-rays with well defined repetition rate, which enables time-resolved X-ray experiments. APS has 24 bunch mode, giving 24 X-ray bunches separated by 153 ns within a period of the storage ring, so simply an X-ray laser with 6.5 MHz repetition rate.
We synchronize our ultrafast lasers that can produce visible/IR light with the repetition rate of the X-rays. Therefore, we can adjust the arrival time of a laser pulse with respect to that of the X-ray pulse quite precisely, the technique known as pump-probe in optical domain
This has similarities to a stop-motion photography or slow-mo which helps to to resolve fast motion happening Image ref:https://t.co/YVERqBkpso https://t.co/FLdx2VqIWj
But, different than macro-scale, we are interested in visualizing dynamics happening at the atomic scale following a laser excitation. Non-equilibrium induced by the excited state and its relaxation.
As compared to complimentary techniques such as optical transient absorption, time-resolved photoluminescence, TR-ARPES etc etc. probes like X-rays and electrons provide the point of view of the atomic structure different than electronic structure and provides new aspects https://t.co/oqxyKEqk1Z
Let’s talk about how optical pump / X-ray diffraction/absorption probe experiments. Why are they useful? And how? https://t.co/0EJpsGzpCP
Two directions: (1) Visualization of energy conversion processes in photoactive materials (Ex/ photocatalysts and photovoltaic materials) by probing how light energy and hot-carriers are turned into into lattice heating or carrier trapping causing local lattice deformations... https://t.co/ROEmte0K13
(2) Manipulating matter with laser pulses and creating dynamic new states. Optical pump/X-ray probe allows probing these states: Ex/ transient phase transformations, light-induced bond-breaking-forming etc.
Before we dive into some cool examples, let’s check out what are key observables in these experiments
In optical pump/X-ray diffraction probe, we basically do XRD transiently. Therefore, observables are Bragg peaks, their positions, intensities and widths.
Bragg peaks may shift to low Q for example. It means the material expands. It typically happens when hot-carrier relax via electron - phonon coupling. There could be other ways that cause shift of Bragg peaks due to induced and relaxed strain in the material. https://t.co/WpNGaES1tK
Specific phonon modes may be launched due to photoexcitation. This can lead to periodic modulation of the structure factor, hence up and down periodic changes of the Bragg peak intensities https://t.co/yx86vVRbZI
Or, some of the Bragg peaks may disappear while other may appear. The number of peaks may go down if the material converts from a lower symmetry structure to a higher symmetry structure. All these changes indicate the unit cell representing the material is now different. https://t.co/SciSMGRp82
Last example of observables in optical pump/XRD probe experiments is the changes in the Bragg peak intensity and width. Peak intensities can go down if the material is becoming more disoredered. This happens, for example, when you heat up a material https://t.co/3kOwe9t8cX
We can also talk about different set of observables associated with optical pump/X-ray absorption experiments. I am showing here a Co K-edge X-ray absorption spectrum. The spectral region around the absorption edge is called XANES - X-ray absorption near edge structure. https://t.co/xZHkz29VuS
XANES region is sensitive to electronic perturbations. Localization of an electron or hole around the element gives rise to shifts to either low or higher energy. As well as pre-edge structures can change due to this.
EXAFS is the absorption that extends many 100 eV away from the absorption edge itself which is mainly sensitive to the local structure, i.e., bonding, around the element withing the material. Changes in this region indicates changes in the bond lengths.
These regions are overall summarized here https://t.co/PlecozD8VY
These hopefully give more concerete sense on what these measurements show and why we do them... Next up: some of the literature examples! https://t.co/WiKbm2W4Uz
[admin] "Dancing Atoms and the Stories they Tell" Extended conversations with the amazing @BGuzelturk is out now. 🎙️👇 #UnderTheMicroscope #SciencePodcast https://t.co/jK6EXYbTu3
Let’s check out some classical work that utilized ultrafast structural measurements and also more recent ones. This is definitely not an exhaustive list of papers but some that I personally find useful (and also a little bit of shameless self-promotion of our work)! https://t.co/2wAbt7KHq6
Early work was focused on using optical pump / X-ray (or electron) diffraction probe experiments to investigate how fast bonds break and how fast materials transform. Questions like how fast can you melt a material or how fast can you break a bond? https://t.co/GmbVIVxrGq
Tribute to late Ahmed Zewail who pioneered a lot in ultrafast comunity. His group’s paper back in 1997 is one of the first to resolve chemical bond breaking in a molecule after photoexcitation. https://t.co/YVXipbSQkw
Another early paper is from Bradley Siwick and Dwayne Miller in 2003. They visualized transient melting of aluminum after laser excitation. Aluminum film can melt as fast as 3.5 ps after laser excitation. https://t.co/AUaZjjeCEl
More recent work attempted to use such measurements to characterize how atomic structure deforms due to an electronic excited state, the so-called polarons which play important roles in optoelectronic properties of materials using for photocatalysis and photovoltaics
An example is using transient X-ray absorption experiments resolving carrier localization and small polaron formation in iron oxide nanoparticles commonly used as catalysts in various applications. They utilized iron edge transient XANES measurements. https://t.co/6WSLRUqqob
More recent example is from our work, where we used transient diffuse X-ray scattering to visualize dynamic growth of point-defect like structural deformations after photoexcitation in lead halide perovskites indicating the presence of large polarons https://t.co/j3iCT4QnGF https://t.co/gVaMLaoXQ1
Also, it turns out ultrafast structural measurements are excellent ways to make transient thermometry of materials at picosecond timescales which is otherwise quite challenging task via optical methods. This allows one to characterize how fast hot carrier cool and lattice heat up https://t.co/zSZzAgEc1R
Therefore, one may call “hot carrier cooling” == “cold lattice heating” https://t.co/AwK5sK9Meo
An example of this is from our work where we looked into hot carrier cooling and electron phonon coupling in gold nanocrystals and showed strong size and surface chemistry dependence. Larger particles have weaker electron – phonon coupling, hence longer lived hot carriers.
However, ligands such as thiols that strongly bound to the gold surface can slow down hot-carrier cooling via transient surface energy transfer across metal – ligand interaface. https://t.co/e2IEpunPM5 https://t.co/uA1ZnkaBvM
Other recent work have attempted to resolving transient strain in materials and especially in nano-objects under non-equilibrium conditions
This paper by Ian Robinson has beautifully resolved transient strain evolution in large gold nanoparticles (>300 nm) by applying a coherent Bragg diffraction imaging technique combined with a pump/probe scheme. https://t.co/IyxohHCHZN
Another example is a recent work of ours where we looked at smaller CdSe/CdS nanocrystals that are used in QLED TVs. Under UV light, highly localized lattice deformations arise due to trapping of carriers on surfaces that dynamically distorts the surface https://t.co/KYzVVgCC9U
Other examples include novl ways to utilize lasers or external excitation means to create useful states of matter for potential applications such as computing, information storage etc...
One such example is electrical pump / X-ray diffraction probe experiment on ferroelectric samples. They looking into speed limits of ferroelectric polarization switching and showed sub-nanosecond regime is possible https://t.co/svChDHJroP
Another cool example using laser pulses to make a transient superconductor. https://t.co/DrgWV5zW9D
Creation of supercrytals upon photoexcitation is also another quite interesting finding in complex oxides. This state of matter could not be created by just heating up or cooling down the material but just through intense laser excitation. https://t.co/XHtqIm1ZNB
Final example is a switch, "crystal symmetry switch". Light excitation generates a shear mode in a two dimensional material and modulates the crystal structure from a high symmetry one to a non-centrosymmetric, a new way to store info with >500 GHz. https://t.co/dF2Sntkrj0
Huh, a long chain of tweets! If you reached this point, congrats!!! Tomorrow I will talk more on the fun aspects of being a beamline scientist and will start talking more on how to get beamtimes, how to prepare and tips!
Synchrotrons are very dynamic places to work at. At APS there are 60+ beamlines, meaning 60+ different experiments going on simultaneously on the experimental floor on a typical day.
There are always new experiments and new challenges. That I find quite exciting. Also, working with people from all around the world is quite fun and a continuous learning experience.
Technique development and improvements at the beamlines is significant part of the job of a beamline scientist in addition to supporting experiments and attracting researchers and forming flourishing user base at the beamline.
If you are new to synchrotron based experiments, but do not know where to start. Check out the technique you are interested in, locate the relevant beamtime and then email beamline scientists working.
Beamline staff will be happy to chat, provide information about the capabilities, if needed set up a meeting and discuss about needs of your potential experiments.
The next step is to get a beamtime is to submitting a proposal. The next step is to get a beamtime is to submitting a proposal which is generally 3-5 pages of document answering questions like scientific purpose, why need for synchrotron, what is the need for specific beamline...
Key aspect is to convince the external reviewers about the feasibility of the experiment in addition to the novelty/importance of the scientific question. Getting feedback from beamline scientists is quite useful before the submission and it definitely does not hurt!
Let’s say that you got a beamtime awarded. Now what? https://t.co/hlhkUXbCqD
Preparation is everything! All the way from sample preparation to logistics, team work and data analysis. Beamtimes are generally for few days to whole week that continue for 24 hr. Therefore, it is not a one person’s job but requires multiple people, an experiment team.
Sample prep and making contingency plans is needed as some samples can turn out to be low quality or degraded. Or, they might degrade under X-rays... Therefore, having a set of samples and various backups is critical.
Another important aspect is the on-line data analysis. Most beamlines have some sort of analysis environments for typical experiments. However, for specific experiments, new data analysis scripts may be needed and users should take initiative to prepare this before the beamtime.
Having data but not knowing what it tells you can be really bad especially when you need to make decisions during the beamtime like what parameters to choose next or scan. Asking beamline staff for exemplary data beforehand to familiarize your self ahead of time is a great idea.
The week is about to end and I have a a short story about a recent paper of mine before my curation ends here @RealSci_Nano
This week one of my paper got accepted in ACS Photonics that will be online soon. This paper has an interesting story with it that I thought I would share it with you all.
During my postdoc, I was studying terahertz emission spectroscopy on various solar energy materials. One of the samples that I studied was PbTe. THz emission showed quite interesting dynamics and spectral responses from PbTe.
We thought THz emission from PbTe may help to explain some of the mistery on optical phonon modes in this material. It has a simple cubic crystal structure but neutron measurements showed multiple transverse-like phonons at zone center that are not expected
Some of these paper reporting phonon anomalies in PbTe: https://t.co/uDKAqq5CbC and potential Pb off-centering https://t.co/nmJzFoi4yc
I did a time-frequency domain analysis (moving window FFT) analysis on my data, and we were seeing delayed responses associated with a transverse optical mode with respect to others and we thought we might be seeing the anharmonic phonon-phonon renormalization in real-time.
If this was true, then it would mean that we could solve some of the mistery in this material...
We got some theory support doing some MD simulations and overall things were looking consistent. I wrote the paper and got it polished it. We were about to submit it. All this was back in summer of 2018.
There was a little point about the moving window FFT analysis that was bugging me. I was worried whether the result can be uniquely explained by different onset times of two modes, so whether there was a real time delay between spectral features.
Before we submitted the paper, I decided to play around more and simulated some signals mimicking the experiment and THz emission. I realized that this type of analysis cannot differentiate phase difference or time (on-set) delay. Therefore, our results were not conclusive!
This was frustrating at first. I had spent many months on the data, experiments and paper... Anyway, I decided to hold off the manuscript.
After three years, last summer I decided to go back and look at the data now with a fresh eye. I realized there was already quite interesting response in the Thz emission that I did not pay attention much as got so focused on phonon anharmonicity aspect.
THz emission from PbTe could be significantly tuned spectrally under varying photoexcitation density. Tunability was quite significant from 3.2 to 2.4 THz and such large tunability was not observed in other THz emitter before. I thought this is something to tell to the community
Therefore, I decided to re-write the paper and still disseminate these results. The reviewers really appreciated the results and the paper got quickly accepted.
I think if we have kept forward back in 2018, that paper could got published... but potentially would create more conflict in the community than solution. I think one of the take-home message behind this story is that scientific rigor is essential no matter what!
Thank you all for interactions this week. For more future interactions, my twitter account is @BGuzelturk and my personal webpage is https://t.co/OCcjdhjkYj. Take care! https://t.co/rxMXcEFhCT
[admin] Huge thank you to Burak for a wonderful week of science! 👏 Do give @BGuzelturk a follow! ✨ Podcasts where Burak speaks about his science and being a scientist are here - https://t.co/ZM8XIcw4Yc #UnderTheMicroscope #SciencePodcast
Mei Hongyan
[admin] "Revolutionising Optics with New Materials" Please welcome @Hongyan_May for a wonderful week of science and listen to the podcast to know what is coming your way this week 👇🎙️🎧 #UnderTheMicroscope #SciencePodcast https://t.co/i0eXCJCGec
[admin] Want to take over this account and feature on our podcast series? 🎧🎙️ #UnderTheMicroscope #SciencePodcast Let us know here - https://t.co/tEAMjLhTnQ
[admin] Know a materials/nano scientist who will be ideal to take over this account? Nominate here 👇✨ https://t.co/7oUVPbyYb1
Howdy Everyone! A chilly greeting from the Midwest United States (🥶24°F today)! This is May (@Hongyan_May) from the University of Wisconsin-Madison🦡. I am a Ph.D. student from @KatsGroup working with new optical materials. Excited to share my journey in nano science this week.
Many thanks to the organizers for creating this great platform for bringing science to a broad public. 👏👏👏I am extremely happy and very honored to be part of the program.
A little more intro about me and my research: I am a 4th year Ph.D. student in @UWMadisonECE under the supervision of Prof. @mickeykats and my research is focusing on engineering and characterization of complex optical systems. There are two main parts here. [1/5]
First, characterization! A big part of my research is to develop advanced optical characterization methods to investigate complex optical materials. This yielded a discovery of a new material system with giant optical anisotropy. 👇our 2018 paper: https://t.co/TzzTYX3vZQ [2/5]
This is a collaborative work with @USCViterbi and recently our author correction was published. I will share the story about how we pinpointed the mistake and self-corrected it. I will also share our most recent discoveries of this material system [3/5] https://t.co/jCWg2WLV05
Another part of my work is engineering optical materials. We utilize a commercial focused ion beam (FIB) system to locally modulate the optical properties of metal-oxide thin films via ion doping or defect engineering. This is a collaborative work with @RonningGroup [4/5]
In simple words, my research goal is to better understand the properties of materials using optical characterization methods, and to further engineer and manipulate the materials. This fundamental science work benefits us to explore and create next-generation optics [5/5]
Wow, this is very helpful! https://t.co/CYUu5gWcNj
I know Thanksgiving is approaching (holiday is coming!) but this week I will still share a lot of research stuff and interesting stories behind. Read below and I'll list what to expect from this week👇 https://t.co/OzPepDqOZp
1. Introduce myself and my journey in the field of nanophotonics. 50% done today and will share more along the way 2. Introduce our group (@KatsGroup) and the facilities in our lab https://t.co/02gLn921E3
3. History and fun facts of anisotropic materials and what we discovered recently. Calcite picture from @Wikipedia https://t.co/5gje4Wh884
4. Introduction of Focused Ion Beam (FIB) technology and applications and what we did with a FIB https://t.co/C86tjaqPZP
5. Interesting science and research work in the field of nanophotonics 6. More than science: optics in daily life, science art, work-life balance of a PhD student, et al. Courtesy of @ErrantScience https://t.co/9b1pOnJRN8
Today I will start with how my journey began. I started my first optics course - Ray Optics during my sophomore year at @ZJU_China, which explains how lens bends the light. After a fascinating lab tour organized by the department https://t.co/QiYrKv1iSS I chose optics as my major
Among lots of fancy facilities and equipment, nanophotonic devices intrigued me the most. I was impressed by how this tiny chip can manipulate light. After learning wave optics and quantum optics, I realized there is cool physics when shrinking the size down into micro/nano scale
After that, I was very lucky to have the opportunity to join a nanophotonics group to do some research projects. https://t.co/0B4ASRmxiw Under the supervision of Prof. Lei Zhang and Prof. Limin Tong, I completed a nanofiber sensor project and published my first-ever journal paper
https://t.co/Ypkiwe1gDM @ACS_Sensors In this paper we designed and fabricated a coiled optical nanofiber structure for highly sensitive and robust optofluidic absorbance detection.Our nanofiber microfluidic chip opens up new ways for ultrasensitive chemical and biomedical sensing
This is a small step but really makes a big difference to me. I am truly grateful to have my undergraduate advisors. Their enthusiasm for science and research inspires me to learn more and deeper in this field. Now I am doing my PhD at UW-Madison. Next I will introduce @KatsGroup
RT @mickeykats: Happy to report that our work on ultrathin reflective optical limiters was included in the @OPNmagazine "Optics in 2021" fe…
RT @KatsGroup: The "hot topic" in our lab today is that Yuzhe's work is featured on the cover of "Laser & Photonics Reviews" 15(10)/2021. C…
I am very excited to introduce our @KatsGroup, led by Prof. Mikhail Kats in the Department of ECE at the UW-Madison @UWMadisonECE We engage in experimental and theoretical exploration of topics across the fields of optics and photonics, nanoscale science, and quantum technologies
Our primary goals are to investigate fundamental problems in optics and photonics and to create next-generation optical components to emit, modulate, and detect light across the visible and infrared spectral ranges. Check out our research highlights! https://t.co/bgzUfdlWYt
Our group has experience in thermal emission and radiative heat transfer, engineering optical properties of materials, device physics, imaging systems, and infrared optical technologies. Our lab has several facilities that enable us to conduct various optical characterizations.
The most important tool for optical characterization in our lab is @bruker Vertex 70 FTIR spectrometer (outfitted with a Hyperion microscope), which allows us to measure reflection/transmission/emission spectra of macro/micro samples across near-infrared and far-infrared ranges. https://t.co/e6tRho7zZa
In 2020, we published the guidelines and general procedures for accurate and precise measurements of thermal emission in a laboratory setting (such as FTIR), which can also accommodate temperature-dependent and nonequilibrium thermal emitters https://t.co/KPAaReuY2G
We also come up with calibration methods for correcting thermal-emission-induced detector saturation in infrared reflection/transmission spectroscopy. These precision measurements are the basics for revealing the optical properties of the sample/structures https://t.co/DlLepz2epW
Apart from FTIR, our lab has several different lasers, detectors, FLIR @flir thermal camera, Hyperspectral camera, and other relevant optical components. All of these types of equipment enable us to do a lot of interesting things for infrared optical science and technologies. https://t.co/KT1dxUpEeY
I guess most of you know "cleanroom", a specific space for nanofabrication. Here in UW Madison, we also have a "cleanroom" - Nanoscale Fabrication Center (NFC), including shared facilities for lithography, deposition, packaging, assembly, plasma etching, wet chemistry, etc. https://t.co/I1l4V21DPp
For fabricating nanophotonic structures and devices, NFC is a perfect place for a complete series of processes. You can imagine people are working in a super clean environment! https://t.co/TtHjc4fyYW
After nanofabrication, imaging and characterization would be the next step to evaluate the performance of your sample/device! Then, Nanoscale Imaging and Analysis Center (NIAC) and Soft Materials Characterization Laboratory (SMCL) would be the two perfect places to go.
https://t.co/3KENVx6I4n At NIAC, you can get access to various microscopic and spectroscopic facilities such as SEM, TEM, AFM, XRD, Raman, etc. These results will give you some ideas of your sample/devices.
https://t.co/x7oLaB2Ngi SMCL has more spectroscopic tools besides NIAC. I'd love to point out spectroscopic ellipsometry, an optical technique for investigating the dielectric properties of materials and structures, which is key to my projects. I'll give more introductions later.
🐶🐕I know dog has night vision but I cannot walk to the park without a torch at night. Also found a small piece of news talking about dog eyes, knowing it's from UW MADISON makes it more fun! https://t.co/Ro6P0dT51O https://t.co/gAGaTMs0Br
[admin] "Revolutionising Optics with New Materials" Extended conversation with the amazing @Hongyan_May is out now. Give it a listen! 👇🎙️🎧 #UnderTheMicroscope #SciencePodcast https://t.co/PcDvWPAQYS
Time for fun facts! Today's topic is anisotropy. Anisotropy is the property of a material showing the difference of the physical or mechanical properties when measured under different directions, as opposed to isotropy. This is a concept across many fields https://t.co/9Nz3S5O3K4
For example, wood is stronger along the grain than perpendicular to the grain. Strength is a property of the wood and this property depends on the direction, which is wood's anisotropy. For more details, check out the wiki page above☝️ Picture courtesy of AhsanAronno https://t.co/TwM6bVljHo
Here I want to focus on the optical anisotropy of crystals. The crystals are anisotropic to light. Many of you may hear of birefringence or double reflection, which is commonly seen in polarization optics. It is interesting to learn about how optical anisotropy develops.
The discovery of birefringence in a crystalline material can be traced back to 1669. Erasmus Bartholinus, a Danish physicist and mathematician, discovered the phenomenon of double refraction of calc-spar (a type of calcite). Pictures from Science Photo Library and Wikipedia https://t.co/C6fBS0O4Zm
In 1690, Christian Huygens, a Dutch physicist (yep who proposed Huygens principle), interpreted the double refraction by assuming that in the crystal there is a secondary ellipsoidal wave in addition to a primary spherical wave, which is the fundamental discovery of polarization.
Isaac Newton explained this phenomenon by assuming that light particles have "sides", and used it as an argument against Hooke's wave optics. At that time, only longitudinal (acoustic) waves were known, and they could not explain transverse polarization.
In 1808 Étienne Malus observed the reflection of direct sunlight from a window through calcite and found the two images obtained by double refraction varied in relative intensities as rotating the crystal.He formulated Malus law and applied first the term "polarization" to light
In 1809 Arago discovered the polarization of light from the clear blue sky. In 1811 Arago observed the optical activity of quartz, and Biot discovered the high polarization of the rainbow. In 1812 Arago constructed a filter from a pile of glass sheets.
In 1815 Biot established the optical activity of certain liquids and discovered the strong dichroism of tourmaline crystals. In the same year, Brewster discovered the law of Brewster's angle, also known as the polarization angle.
In 1828 Nicol invented a prism, which was the first easily usable polarizing filter. After that, the theory and experiment of optical anisotropy and polarization optics were being improved and developed. The story never ends. Next I will introduce what we discovered on this topic
Source and reference: 1. Historical notes on anisotropy https://t.co/Ed4xVmUzaw 2. Gabor Horvath’s thesis https://t.co/UdanJMIt2G 3. Conifold's answer from @StackExchange https://t.co/iUBV1VPcPx 4. https://t.co/WCZZnzJDBJ 5. https://t.co/jCqsslR4YF
Why do we care about optical anisotropy? In the sense of polarization optics, there are devices that we commonly use, such as wire grid polarizers, polarizing beam splitters, waveplates... All of them rely on some kind of optical anisotropy to manipulate the polarization of light https://t.co/qd4g1l52tB
For wire grid polarizers, structural anisotropy in terms of patterned wires can absorb/reflect light at a certain polarization. But for PBS and waveplates, the anisotropy comes from the crystal structure itself of the material. For these systems, large anisotropy is the key. https://t.co/VLGUJEjt6P
For uniaxial materials, birefringence is to quantify the anisotropy of a material, which is the difference between extraordinary (along the optical axis) and ordinary (perpendicular to the optical axis) refractive index (delta_n). https://t.co/fLLe7lskOx
The most commonly-used birefringent materials are calcite, rutile, and cadmium selenide. Calcite has a large birefringence span UV through near-infrared. And rutile extending more towards mid-infrared. Cadmium selenide is another birefringent material working in mid-infrared.
But you can see their delta_n are actually very small. So this leads to a question, can we find, or create a material that is highly birefringent across the infrared ranges? And this leads us to this concept of engineering the polarizability of a crystal structure.
Given the idea of polarizability engineering, we looked at a perovskite-type crystal structure. Its crystal structure is anisotropic and intrinsically has in-plane anisotropy. https://t.co/BGvvLLTIe3
Besides the fact that the crystal is anisotropic, we also need to think about what kind of chemicals can we use to maximize the polarizability difference between the planes. So we want to pick chemicals that give us lower polarizability in one direction versus the other. https://t.co/Zb6Iw9m8pM
In this case, barium, titanium, and sulfur provide good candidates. And this is our first attempt at engineering polarizability. In 2018, our group, together with Prof. Ravichandran's group and Prof. Han Wang's group from @USCViterbi reported giant birefringence of BaTiS3 (BTS)
https://t.co/TzzTYX3vZQ In this paper, we reported a difference between the ordinary and extraordinary refractive index up to 0.76 in a mid-infrared region of transparency, which is the largest of any bulk material with the in-plane optical axis that we know at that time. https://t.co/v02McOop6j
But after that, during an experiment we found that the refractive indices of extraordinary and ordinary of BTS were mixed up. Actually it has positive birefringence instead of negative in the infrared range, and its giant anisotropy still works. This mistake was surprising to us.
After that, we submitted the author correction and right now it's up online. https://t.co/jCWg2WLV05
So I'd love to walk you through how we characterize this anisotropic material and how these mistakes occurred. As a super early-stage researcher, it's worth learning and thinking about "science is always self-correcting"
For this work, we came up with a comprehensive optical characterization method by combining polarized infrared spectroscopy with generalized spectroscopic ellipsometry. This allows us to extract optical properties spanning UV to mid/far infrared range. https://t.co/8022uWr5G0
We used VASE from @JAWoollamCo to collect ellipsometry data across UV to near IR range. The idea of ellipsometry is to build up an optical model that can fit the values. here we created a generalized oscillator model that is a summation of Kramers-Kronig- consistent oscillators. https://t.co/wFUi1MdoXx
To further expand to mid/far infrared range, we can include the polarized reflection spectroscopy data in our fitting data set. By manipulating the oscillators, reflection data can also be fitted. https://t.co/5uzQGSriLz
From that, we're now able to extract the optical properties of BTS from UV to mid/far IR. As I mentioned above, we ended up mixing the ordinary and extraordinary refractive index. This is due to two mistakes we made during the fitting.
The first error, we found that wrong Euler angles were defined in the model. The ellipsometer we used defines the c-axis into the substrate (out-of-plane), but we set the c-axis along the substrate (in-plane), which rendered a 90° offset. https://t.co/5KLD6z0lkq
Second, the direction of our IR polarizer was mixed up. Wire grid polarizer is vertically polarized when the value is set to be 0° but we did it wrong previously. So the sets of the polarized reflection data are flipped for perpendicular and parallel directions during fitting. https://t.co/N1NstHXCNv
The lucky thing is they both got 90° offsets and the two errors actually cancelled out, so the fitting is still valid, but the definition of the axes was wrong. To make it more clear, I put the original figure in the paper and our corrected figure here. https://t.co/SeqLuVSl2e
By now, it seems we are done with BTS but this group of perovskite material really has a lot of interesting things to explore. So besides BaTiS3, we also looked at other combinations of elements to get a better understanding. Further interesting works are in progress.😉
@guangweihu Thanks for sharing Guangwei! Very nice work!
@nilaRdivaD @ACS_Sensors You are right the general geometry is quite similar. The coiled structure is to make the detection length longer, which is not new. The novelty here is the use of nanofiber (as the sensor) integrated with the microfluidic chip (as the specimen chamber).
@nilaRdivaD @ACS_Sensors As you can imagine, the two ends of the nanofiber can be directly connected to the light source and the spectrometer so that we can directly detect the specimens in the chamber by checking out the change of the spectrum.
This paper reports an unfamiliar polariton in anisotropic materials, which is ghost phonon polaritons. Very interesting work! https://t.co/73bAHRHlv4
@bray_mur @BMatB Thank you Brayan! Happy to discuss if you have any questions.
🦃Happy Thanksgiving to those who celebrate!!! May all of you enjoy the warmth of family this season and the harvest of the feast! Happy Turkey day!!! https://t.co/5ApIFuyBHx
RT @ProfFeynman: You are under no obligation to remain the same person you were a year ago, a month ago, or even a day ago. You are here to…
RT @NaturePhotonics: New content online: Efficient solid-state photon upconversion enabled by triplet formation at an organic semiconductor…
Yeah, tell me about it.🤦 https://t.co/KyflZ8iJGF
Happy weekend! Today I am gonna talk about FIB (focused ion beam) technology and what we did with a FIB!!! https://t.co/pCKPMUQUlQ https://t.co/Q0iKfcCacJ
Focused ion beam (FIB) is a technique frequently used in semiconductor industry, materials science, and biological field. A FIB instrument is almost identical to an SEM, but uses a beam of ions rather than electrons. Pictures from: https://t.co/l96Un7Vpyy https://t.co/X2dhK5Hp6v https://t.co/Axhr3xeBcL
FIB is a well-established technique for high-resolution area-selective milling and deposition. We can use a FIB to directly mill the specimen surface, which can be controlled with nanometer precision. FIB-assisted deposition has also been broadly used in micro-/nano-modification. https://t.co/DR6xbxeqOF
Our new effort is to use a FIB to realize direct writing, mask-free, any number of doping levels in a single step. We demonstrate the spatial modification of the optical properties of metal oxides (zinc oxide ZnO and vanadium dioxide VO2) using a commercial FIB system.
First, we demonstrate ion implantation using FIB, where we used zin oxide (ZnO) as a host material. Using a 30keV Ga+ FIB and thermal annealing, we demonstrated variable doping of ZnO, achieving plasma wavelengths from the mid-infrared to the near-infrared range. https://t.co/ABj1e4yTiQ
Then we demonstrate defect engineering of VO2 using FIB. FIB implantation (without annealing) can also be used to introduce structural defects into a material, and the induced defect density can be continuously controlled by varying the ion fluence. https://t.co/AXafqfGciO
Such defect-engineering techniques can be useful for locally modulating the insulator-to-metal transition (IMT) temperature of thin-film VO2. We achieved a reduction of the IMT temperature by ~15 °C in VO2. https://t.co/fSsJLd3RXe
The FIB process doesn't require lithography or masking process. Due to the versatility of commercial FIBs, this technique can be used to modify and engineer materials with high resolution even for irregularly shaped materials where conventional lithography is challenging.
I wouldn't mind giving it a try!🧑🔬 . . . . . . . . . . . . . . . . for a kitchen cleaning.🧽 https://t.co/iwW5Q6Ntqw
RT @realscientists: Welcome to the best week of your life 🙌🏾🌊🧜🏾♀️🧜🏿♂️💯 #BIMSWeek is a week dedicated to amplifying Black marine scientist…
@Felgraf_Physics That's a good idea!
RT @devbiodelfi: Dear fellow #scientists, Can you describe a time you lost your love of science? What triggered it? How did you re-discov…
I am right in the middle of this timeline from @PHDcomics and found the road towards a PhD is sometimes bumpy and winding, but we are definitely getting there! Hope every graduate student can embrace the challenges along the journey and live a happy life! 💪 https://t.co/I5KvoanPvR
Dear all, hard to say but it's time to say goodbye👋Today is the end of my role as a curator. I was having a great time sharing my research and journey and interacting with you all. It's a lot of fun! Saying Goodbye The Muppets Take Manhattan https://t.co/2ij2kVfzPz via @YouTube
For more questions and future interactions, feel free to DM or tag @Hongyan_May and follow the research of our group @KatsGroup https://t.co/02gLn921E3 Really looking forward to the next curator in the coming week! I will see you around on Twitter.🖖🫂
RT @RealSci_Nano: For more questions and future interactions, feel free to DM or tag @Hongyan_May and follow the research of our group @Kat…
[admin] Huge thank you to @Hongyan_May for a fantastic week of science about optics, FIB and much much more! 🥳 Do give her a follow! ✨ Podcasts where May speaks candidly about herself and her science are here - https://t.co/BzU6wNTb5S #UnderTheMicroscope #SciencePodcast https://t.co/6CHfEK1WnE
Andrea Armani
[admin] "A Nanomaterials Patchwork" Please welcome @ProfArmani of @ArmaniLab for a wonderful week of #materialsscience Listen to the #podcast to know what is coming you way this week 👇🎧 #sciencepodcast #nanoscience #UnderTheMicroscope https://t.co/RIiYpjb5BA
Really excited to get started! My plans: highlight some of my favorite #nano articles from the past century (not a typo) and pass on amazing career advice and websites that I think are helpful. But I'm hoping that all of #ScienceTwitter will join in - especially on the latter!
To get started, @WillisWellbeing shares some great advice (and resources) on tackling a huge problem in academia: #ImposterSyndrome. #phdforum #advice #academia https://t.co/undgRAvNqH
@KamatlabND @ProfArmani @ACSEnergyLett This is EXACTLY the type of work that new students and researchers should read! Thank you for the enormous effort that this article required! https://t.co/4p1gWkRa3z
We're beginning our nanomaterials history w/ one of the original materials: metal nanoparticles. This material is the foundation for plasmonics, which has its roots in Mie theory - original 1908 article: https://t.co/phErkjifwF (one hiccup: It is in German) 🪡 #chemtwitter 1/N
But, no fear, @SandiaLabs translated it to English! Link: https://t.co/qHIlJsaO9f Sandia Laboratories, Albuquerque, New Mexico, 1978, SAND78-6018. National Translation Center, Chicago, ILL, Translation 79-21946. @SandiaLabs 2/N
While Mie laid the foundation, Kreibig really began the exploration into “plasma” resonances in metal nanoparticle systems (also called nanoclusters) in a pair of papers in 1974 and 1975: https://t.co/LL1htqDHl9 @springerpub #AcademicTwitter 3/N
Paper two: https://t.co/Vqe22lID3H @IOPPublishing This pair of papers truly sets the stage for the field. #phdforum #phdchat 4/N
But, of course, no discussion of plasmonics would be complete without mentioning the Lycurgus Cup, which was a nanotechnology before the word was in the "dictionary"! 5/N @chemistryworld @RoySocChem https://t.co/2CVE7nSQJ9
[admin] For day 14 of our #MaterialScience #AdventCalendar we've been gifted #silver 🥈 Its antibacterial properties lead to its use all over, from cutlery 🍴to🤕to🏊🏽. But be careful, ingesting it can turn you blue 😲 ⬇️Where do you use Ag in your life or #science? https://t.co/PubpODn7bY
Quantum Dots are a perfect example of how a name change resulted in history being lost. Originally called quantum heterostructures, then quantum boxes, the name “dots” is a semi-recent term. Today, we're going to explore this evolution! #sciencetwitter #nanomaterials #phdchat 🪡 https://t.co/kT3bvuId0b
They began as a way to study quantum mechanics. First proposed in 1963, one of the first demonstrations was in 1974 by Dingle and Wiegmann from Bell Labs using a AlGaAs-GaAs-AlGaAs quantum well structure to study energy states of GaAs. https://t.co/c5O7qk1Zn8 @APSphysics
This work led to several landmark papers, including the first demonstration of a quantum well laser in 1978: https://t.co/2KMa29Ra7w @APSphysics But, both of these papers involved epitaxy-based growth methods.
To transition to largescale production (& enable apps like bio-imaging), it was neccesary to develop a wet-chemistry method. In comes the Chemists, & a pair of articles by L Brus from the 1980’s in J of Chemical Physics @AIP_Publishing https://t.co/EZn6JfhdbT (Pic is wrong)
Article 2: https://t.co/4qRESg9l18 To differentiate these from the planar "quantum well" system, they were called "dots". #chemtwitter (Note: the picture is wrong)
With both planar and liquid synthesis approaches in hand, researchers began exploring applications as well as new material systems to reach new wavelengths. And thus, the entire field of Quantum Dots/Wells was launched! #AcademicTwitter #technology https://t.co/w18fjJ9PM0
As one last comment, I hope everyone notices that none of these papers (or yesterdays either) are in CNS journals. Yet, these are the landmark papers that established entire fields. In other words, it is the work that matters. #AcademicTwitter #AcademicChatter
Timeless advice that is applicable to everything. https://t.co/KxqTGB7UHN
Today's career #advice: Don't give up on your dreams. Corollary: Make sure you are actually pursuing your dreams. As an example, I'm re-posting my PhD story. This is just the beginning, which wasn't exactly smooth after this either. #phdchat #phdlife @AcademicChatter https://t.co/9Dehxk9yqs
[admin] "A Nanomaterials Patchwork" Extended conversation with the amazing @ProfArmani of @ArmaniLab is out now. Give it a listen! 👇🎧✨ #sciencepodcast #nanoscience #UnderTheMicroscope https://t.co/NYSwpM0vbV
[admin] On day 15 of our #MaterialScience #AdventCalendar, let's chat about #Tungsten! It was used in 💡filaments because it stays strong and solid at high temperatures. Both hard & hypoallergenic, it's also good for scratch-proof jewelry💍 ⬇️Does W appear in your life or #STEM? https://t.co/GdFFb8JU0H
Today's topic is Carbon from "0D to 2D"!! (though the dimensionality is up to debate) Starting in 0D, we have the Buckminsterfullerene structure - also called the Buckyball! This was first shown in 1984 in J Chem Physics @AIP_Publishing . Link: https://t.co/s8yWVbuMVa
After improving the syn method, this work was REPEATED & published in @Nature w/ the recognition of the C60 structure: https://t.co/VQMUUySRPJ I'm emphasizing that this work was a repeat (essentially) b/c this so rarely happens now.
As an example of “always keep your eyes open” in research, Huffman & Kratschmer noticed that the carbon soot produced by arc-discharge between two graphite rods contained C60! & this soot contained something else… https://t.co/MqgeooUTQ3
If you guessed carbon nanotubes (CNTs), you’re right! In 1991 – just one year later – Iijima published the landmark, solo-author paper on the structure of CNTs: https://t.co/kTP8CHtuSl While this work definitely laid a foundation, in some ways, it asked more Q's than it answered.
For example, does chirality impact the properties of CNTs? (#spoileralert: yes!) This was demonstrated in a pair of PRL papers: 1)https://t.co/rfCHoN4j1A 2)https://t.co/heyfHs3V17 @APSphysics @PhysRevLett
Subsequent work has focused on developing ways to improve/control the synthetic yield and deposition, to better understand structure-property relationships, and to integrate with other materials systems. But also, “unrolling” the tube to obtain…
The carbon sheet – or Graphene! This 2D material was actually discovered twice. First in 1962: link: https://t.co/3o50JDP7DK (in german)
And then – again! – in 2004: link in @ScienceMagazine : https://t.co/aQ2TjAM79W And subsequent works used my favorite material fabrication method: micromechanical exfoliation AKA "the scotch tape" method. It shows how discoveries don't always need fancy/expensive equipment.
Both experiments relied on a pair of theoretical works that predicted the conductivity based on the lattice structure (1947) & then connected that to quantum field theory (1984). (This is a huge simplification.) https://t.co/pw2SsrmmPT https://t.co/sykK91esoT @APSphysics
So, what is 3D carbon? Graphite. If you're still with me, what is your favorite nanocarbon paper - from last century or this one? #sciencetwitter @AcademicChatter #AcademicTwitter #chemtwitter
[admin] For day 16 of our #Materials #AdventCalendar we've got #titanium! This metal is light, strong and compatible with human tissue, so it is used for dental and orthopedic implants 🦷🦴 ⬇️Quiz: Why don't our titanium implants set off metal detectors at the airport? 🚨✈️ https://t.co/NNSEwUOcFt
As we're heading (have headed) into the holidays, this @PHDcomics seemed particularly relevant. I am a big fan of OOO emails, as they help manage expectations. Though, as I don't have an assistant, I guess people who email me are just stuck in limbo? #PatienceisaVirtue #PhdLife https://t.co/5q936thBWh
Just a reminder to take care of yourself over the holiday break, because you matter. #Mentalhealth #AcademicTwitter @PhDForum https://t.co/XWyZYA7a7z
[admin] For day 17 of the #MaterialScience #AdventCalendar we've been sent some #aluminium/#aluminum This might not seem like an exciting 🎁 but remember: Al 🥫was more expensive than gold 🪙 until the mid 1800s (thanks, #electrolysis!) ⬇️Let's talk about Al's many uses 🚀🪖👩🏽🔬🚗 https://t.co/g2XztrXkNF
As students shift from the "applying" to "deciding" mindset, this series of podcasts and videos from @darren_lipomi are a must-watch! And I'm sure the members of @PhDForum have more advice! #advice #lifehack #sciencetwitter https://t.co/JvXEWy7chz
[admin] On day 18 of our #MaterialScience #AdventCalendar we have #Nylon 🧦 Or nylonS? This family 👩👩👦👦of #polymers might be the most famous synthetic fabrics ever. Moldable, dyable and resilient, they have many everyday applications 👗🪥🪛🧴 ⬇️got some fun nylon #chemistry facts? https://t.co/ENGcKimVt8
[admin] For day 19 of the #MaterialScience #AdventCalendar let's talk #Nanocrystals! 🔮 Like all #Crystals, they're made of #atoms arranged in a nice, tidy, pattern 🎁 But small! ⬇️How incredibly small is your favourite nanocrystal? https://t.co/wJ738hTF1l
[admin] On day 20 of our #MaterialScience #AdventCalendar we have a classic group of #materials: #Ceramics! 🍯 We've been shaping and heating to make ceramics for over 25000 years 🧓🏾🪴 but it took until the 1980s to make them #nano ⬇️Who uses/studies ceramics in their #STEM? https://t.co/a29Xnd7c6s
Thanks for letting me host! I hope everyone has a wonderful, restful holiday season and happy new year!
[admin] For day 21 of #MaterialScience #AdventCalendar we have #Gold 🥇 We've been smelting it for ~6000years to make 🦷🥇🪙👑 because it's malleable and not very reactive. ⬇️Our scientist is holding some Au in her test-tube. But why does it look red and not...well, golden? https://t.co/Mz7f7rkEpr
[admin] Huge thanks to @ProfArmani for a wonderful week of science! Do give her a follow! ✨ Podcasts ft. Andrea are 👇, do check them out! #UnderTheMicroscope #materialsscience #nanoscience #sciencepodcast https://t.co/zgzTYJ2ZPh
2022
Chris Nicholson
[admin] "Filming Electronic Movies in Emergent Phases" Please welcome this week's curator @chrisw_nich for a wonderful week of science and listen to the podcast 👇 to know what is coming your way this week! 🥳🎙️ #UnderTheMicroscope #sciencetwitter https://t.co/wqdL8Iducd
Hello everyone! My name is Chris (@chrisw_nich) and I'll be your host this week, coming to you from the FHI @fhi_mpg_de in Berlin! https://t.co/upWMjCix7Z
@chrisw_nich @fhi_mpg_de Schrödinger's cat says hi too.
@chrisw_nich @fhi_mpg_de This week I'll be telling you about my work looking at electrons in solids, and how we can understand macroscopic behaviour based on the way electrons organise themselves.
@chrisw_nich @fhi_mpg_de Send me your thoughts, questions and whatever else you like! I'm looking forward to this 😀
So first a few words about me: I'm originally from Edinburgh, but it's already been 10 years now since I left Scotland 😱: how time flies! https://t.co/xv6AFbFEuA
And where have I been living since then, I hear you ask?
@XtalGrrl Yeh, love those clear blue days!
Since leaving Scotland I've lived in two locations: maybe you can guess them based on the photos? https://t.co/PY2YZHwocy
Well done if you got it! The answers are #Berlin (Germany) and #Fribourg (Switzerland). Both great places, although pretty different to each other!
So I've just recently moved back up to Berlin to start my own little group as part of the Max Planck Society @maxplanckpress at the Fritz Haber Institute @fhi_mpg_de. Here are some pics from close to my office: it's pretty chilly today but there is some blue in the sky! 🥶 https://t.co/WbpPWs2ADv
@maxplanckpress @fhi_mpg_de Check out the FHI website here: https://t.co/cffhkSpbff The institute has 5 departments, each with a different focus, relating to matter and energy at surfaces and interfaces.
I spent a few lovely years in the physics department at the university of Fribourg @UnifrPhysics.
Ok so what about the science? Today I'll keep it to a general introduction that should help with the rest of the week.
For that we'll go through three easy steps: 1) emergent phases and where to find them 2) electrons get organsied: electronic structure 3) making an electron movie: ultrafast dynamics Sounds like fun? I think so 😉 https://t.co/K8fUvzBqiJ
First off: "emergent phases and where to find them". https://t.co/XPjuADZEX1
Let's start with a question: have you already heard of "emergent" behaviour?
@LRotheray Especially relevant for a Monday! 😅
Great there are some experts in the audience: you can keep me right!
So we can find examples of emergence all around us, nature is full of it! The basic idea is how collections of objects behave differently from individual objects in isolation. https://t.co/ZtZoG92FhN
@sfmaehrlein Don't worry, there will be plenty of emerging buzz 😉 https://t.co/rNYfpV4jDG
So in the example pictured here, a large number of fish form into tightly formed shoal, as a way to deter predators. This collective response is an example of emergence.
Sand dunes formations are another example: one grain of sand is, well, just that. But many grains together form into beautiful and dynamic shapes. https://t.co/jPkbts2OAt
And one for the winter season: those gorgeous geometric patterns that appear from frozen water drops, each one subtely different to the last. Snow! https://t.co/GjALHPzHWJ
Not much snow in Berlin so far this winter, one thing I'm going to miss from Switzerland.
In my research I'm interested in the collective behaviour that appears in materials, specifically in solids.
Solids are made up of lots of atoms, and have a huge number of electrons jostling around inside them. With all those charges running around and interacting with each other, something interesting is bound to happen, right? https://t.co/RKNleojokv
One quite famous example of that is superconductivity: electrons passing through a material without any resistance at all! Maybe you've seen these "floating" crystals before? Those are superconductors! Wow! https://t.co/rG7rAjKggm
There are lots of amazing emergent behaviours that pop up in solids: feel free to share your favourite in the comments! https://t.co/oRPVR2dyJv
Personally I've been thinking a lot recently about materials that switch between a metal and an insulator because of the strong repulsive interactions between electrons: the "Mott transition".
RT @Prokaryota: Applying for a postdoc fellowship in the UK? Here's a list of 100 Q&A questions to help you prepare for the interview 🙌💬 St…
@DanGRMead Interesting question! I guess in the dune example the sand doen't exactly behave like a liquid (which should flow to have a flat surface) but it's certainly not a typical solid either... Scale is definitely key though. https://t.co/IVyy1imESV
@DanGRMead Right. Whether we're talking about nanometers or kilometers, femtoseconds or years, we'll find different behaviour appearing at each level.
So with all those many many electrons running around inside a material (roughly an Avogadro number!), how can we start to make sense of what's going on? Sounds like a lot for a Monday... https://t.co/5PXh8XzuHZ
Remember the Ever Given? That was less than a year ago😳.
That brings us to "electronic structure", or how electrons get organised. We'll take a closer look at that tomorrow, and we'll venture into the lab to see where the magic happens! https://t.co/hRHVNHMtpO
I'll still be around for a bit in case anyone has thoughts on today's material 😉
So we cover the spectrum pretty well! Hopefully after today there are a few more people with some idea of emergence 😄
Hi again everyone: today I'll talk a bit about how electrons are organised in materials, and venture into the lab! While I prepare some material, let's see how everyone's doing: How do you like Tuesdays?
So as we saw yesterday, there are LOADS of electrons in your average material. How can we organize them? We do this with the "band structure", for which a quick image search gives us lots of funky stuff! https://t.co/iS1vRZu7Tz
These busy figures are sometimes affectionately called "spaghetti" plots 😅. https://t.co/Jn70Ets4XJ
@bkpipr I'm not an expert on calculations myself, but there are lots of good online resources. I'll try to look something out.
So where do these "bands" come from?
Ok let's start from the top with a very simple "material": two hydrogen atoms "A" and "B". https://t.co/bFMRWCEI6U
Each atom has a single electron that is found somewhere near the nucleus. Exactly where, we don't know, but the possible locations are shown by the little peak above each atom, representing the wavefunction.
Both electrons will have the same energy level (shown on the right) when the atoms are far enough apart that they don't see each other.
And if we bring them close together so they can see each other? What happens then to the energies of the two electrons? https://t.co/kWZXncg9Hd
The region in red is key. That's where the atoms can interact: where their wavefunctions overlap.
Now instead of two separate atoms we have one combined system, and it's the combinations of the wavefunctions that give us our new energies.
Turns out we have two ways to combine these two electrons, as sketched here. Remember, it's that interaction region in red that's key! https://t.co/fnWKp1wArm
We can either have a combination that adds togther in the interaction region (which we call "bonding") or subtracts and gives a zero crossing ("anti-bonding").
These two possibilities have different energies, with the bonding state lower in energy than the anti-bonding one.
As we add more atoms to our little system, there are more and more ways to combine all the electrons, so there are more energy levels! Here's a nice way of seeing that that I've taken from Hoffmann's paper: https://t.co/Q8uwVfTZK5 https://t.co/Z9q1I5xXLJ
The dark and light balls represent the bonding and anti-bonding type pictures I drew before.
So now we have a whole lot of energy levels. But it would still be useful to organise them a bit better.
To do that we use not the real-space positions of the electrons but their MOMENTUM (k) in the crystal as an index along the x-axis. In this case we still have the bonding states at lowest energy, and the anti-bonding states at higher. Hoffmann: https://t.co/mhkoi8kpvd https://t.co/HcRVUhtBjQ
And that is our "band" in energy and momentum space. All the complex spaghetti from before comes from this, just with more and different atoms! https://t.co/1g84DhYDBN
Phew, we made it! And as a reward, this afternoon we can go and take a peak in the lab 😉. https://t.co/DYvnD0Zjjh
Tuesday does not seem to be popular 😅.
@LRotheray You have a good eye for detail! Certainly for the purposes of this discussion the size is unimportant. Whether the size meant something to the author of the figure is not explained explicitly in the paper.
RT @flagshipprein: What about physics as a career to you, girls? Join a webinar in zoom to listen inspirational women talking about fascina…
So there is a little effort required to get into the labs here. https://t.co/VkaoQrPxrw
As you can imagine, it can be annoying if you forgot anything outside... 😅
But we do this to keep the space as clean as we can, limiting the amount of dust in the air.
And that can make a big difference to the lifetime of our equipment! We use high-powered lasers for our experiments, and even small amounts of dust can burn and damage the mirrors and lenses we use. https://t.co/vKUSoTSTUU
Here are a few photos from around the lab. https://t.co/69h589IHie
We do a lot of our work in vacuum, meaning we can't just put our samples where we want them with our bare hands.
Remember that scene from Interstellar when they have to dock the space station? Sometimes that's what it feels like when we're moving our samples around: one mistake and it's all over 😳. https://t.co/qPw39y4cVz
And here's a little schematic of the vacuum chambers to put things in context. With this setup we can measure the band structure of materials that we discussed earlier, and even grow some of our own samples! https://t.co/tTF1yYZTD5
@svenja_lohmann A piece of ceramic used to electrically isolate different parts of our detector, which starts at the metallic cone you can see.
@svenja_lohmann https://t.co/2P8sRfIuhy
There are actually a couple different electron analysers attached; here's a sketch of how the "classic" version works. The big hemisphere is a charged capacitor, and the electrons are spatially separated inside it depending on their energy. https://t.co/6KO2I7ReWN
I should say that we use laser light to kick electrons out of our sample and into the detector. People also do this a lot at synchrotrons.
The electron analysers allow us to map out band structures, giving us both beautiful images and a way to better understand why materials behave the way they do! https://t.co/AzbQ8mA32B
Here are a couple of example from our own work: https://t.co/7luncCToZg https://t.co/zNcjFKXoxB
https://t.co/DTcUuB15eL https://t.co/KpiXi9eTll
@AndyWitney Sorry to have dredged up painful memories! Vacuum can be a real pain sometimes😅
Share your favourite band structure images with us! https://t.co/ds2LMCQVzb
RT @the_ScienceTalk: Hey look, it this week's Real Scientists Nano curator @chrisw_nich 👋 To find out more about his experiments (and sart…
@bkpipr In the lab here we're usually into the mid to low 1e-11 mbar range, which can be really useful for very sensitive samples!
[admin] "Filming Electronic Movies in Emergent Phases" Longer conversation with the amazing @chrisw_nich from @fhi_mpg_de is out now! 🥳🎙️ In this one Chris gets candid about his career journey, his fav experiment and a lot more! #UnderTheMicroscope https://t.co/yV1R49UBZJ
@YunfeiHuang7 The "new generation" of ARPES spectrometers are time of flight analysers. Instead of having the electrons disperse through a hemisphere, the energy is determined from how long it takes them to traverse a long tube.
@YunfeiHuang7 What's especially cool about that design is that you can measure energy and both momentum directions all at once, without needing to physically rotate your sample!
@YunfeiHuang7 Here's a nice example, where you can see the beautiful data sets (which are very large!) that can be obtained with this type of analyser. https://t.co/ZFlIeBUHWi
@YunfeiHuang7 I'll talk a bit more about them today, as we also use them for our femtosecond dynamics studies in the lab...
@YunfeiHuang7 To the second part of your question: apart from energy (and the corresponding momentum span) the main comparison points are probably pulse length and flux.
@YunfeiHuang7 Sychrotrons are pulsed sources, so there isn't a continuous beam on the sample at all times. They typically have a pulse width of the order picoseconds which allows for very high energy resolution.
@YunfeiHuang7 Laser sources can be pulsed (like the one we use in our lab) or continuous, although for some energies one is easier to do than the other. For example, we produce laser photons at 21 eV, which pretty much has to be done in a pulsed way.
@YunfeiHuang7 It can be challenging to get enough photons at those energies, but there are a few tricks to make it work. (In case you're interested: https://t.co/eSKKfXGE4t)
@jennifer_fowlie 😅
RT @chrisw_nich: Check out my chat with @MySci_PK where we talk a bit about my scientific journey from @PhysAstroStAnd through @UnifrPhysic…
Hello hello! I thought I'd talk a little about scientific writing this morning, and then this afternoon a bit about those ultrafast electron movies that you've all been promised!
So who actually enjoys scientific writing? Feel free to share why or why not as well!
@yolicomoelrio That's a great point: thanks for sharing! And don't worry, feeling unsatisfied with what we write ourselves is totally normal 😅. I often find it helpful to get specific feedback from a colleague, maybe you can try that?
So *spoiler alert*🚨 I quite enjoy scientific writing. The main stumbling block for me is getting into the right head space to focus on it properly.
For me that means setting aside a good chunk of time that will only be used for writing (an entire afternoon, say) and setting an environment where I'm relaxed and free from distractions. https://t.co/wAu0slkqQf
Actually finding that environment can be far from easy!
Personally I love to use ambient music to help me relax and to stop me thinking about the many other things I also have to do.
I started using this while writing my PhD thesis, and it took a while to work out what really worked for my brain. I tried cafe noises, white noise generators etc. But music (without lyrics) works best for me.
One of my favourites at the moment is a short piece of music looped. The point really isn't to actively listen to the music, it's just there stopping other distractions taking over. https://t.co/hZlA5HtggB
@Michael01806057 Very nice indeed!
What strategies do other people use?
@JoFeanelwa Nice!
@marjolaineminot Thanks for the suggestion! 😊
@chrisw_nich Once you have some ideas down it's much easier (I find) to go back and edit what you already have and then continue from there. Clearly for everyone there will be different ways of getting into the writing flow! https://t.co/QVcjQGilLG
RT @chrisw_nich: Once the environment is right, the next step is getting started! https://t.co/tnYwnuafHs
RT @chrisw_nich: Getting those first words on the page can be tough. Usuallly I jot down a sort of abstact for whatever I'm writing: a shor…
RT @chrisw_nich: Some people I know like to make a list of what they will include in rough order; that's also a good option.
RT @chrisw_nich: Generally it's a good idea to have a rough idea of where you're going before you really try to get into the details. So ma…
RT @RealSci_Nano: @chrisw_nich Once you have some ideas down it's much easier (I find) to go back and edit what you already have and then c…
So what about those movies? https://t.co/1KLygJvwBh
As I mentioned in the podcast chat, I'm interested in the DYNAMICS of electronic strucures (see also yesterday: spaghetti 😉)
What that means for me is looking at how electrons behave on really short timescales: 10^-15 s or "femtoseconds". https://t.co/4hDJH2s1Gm
We need to look at those very short times since that's where electrons do stuff like transfer energy. They are ultra fast! https://t.co/9KvGSbzkT9
So our experiments use pulsed lasers to measure at such short times. Basically it goes like this: Excitation pulse (red) Wait... Probing pulse (blue) Electrons are detected https://t.co/Le4M3ODlHn https://t.co/vYYuYvfiX5
So the excitation pulse gives energy to the system, and then the probe pulse takes a snapshot of what the electrons are doing depending on how long we wait between them.
If we change the delay we can see how the electrons behave at all time points after the excitation pulse, and putting all those snapshots together we get a moving view on the electrons!
It's kind of like making a slow motion movie: we take quick snapshots at lots of times and then put it all together. https://t.co/fT5PR39UYU
And just like the video of the bursting water balloon helps us see how that process occurs, our electronic movies help us see the details of what exactly is going on inside materials! https://t.co/WgjNXnv5os
Stay tuned for some real life examples!
Like I said before, in our lab we use pulsed lasers to follow electronic behaviour down at the femtosecond timescale. The kinds of materials we're interested in can often dramatically change their physical properties. https://t.co/kiwfhDaqnh
Here's one of our electronic structure movies. https://t.co/FftlR8qGhW You can see really clear differences before and after we excite the material (check out the timer on the right). https://t.co/BdEu5S3d2R
From this data we can extract a lot of information about about the way this material behaves, both from the electronic and crystal point of view. Pretty neat, huh?
Using different types of analysers gives us the opportunity to measure different aspects of the dynamics too, for example with a "momentum micrscope" we can look at scattering all throughout the Brillouin zone at once! https://t.co/I6wVbsWRyQ
And we can also freeze the movie and take a more detailed look at the full electronic distribution. So beautiful! https://t.co/4rEnOxftFi
@johannaphys Glad you enjoyed! 😊
@LRotheray Yes good question! It's very similar: the vertical axis is energy and the x,y directions are mometum along different crystal directions. So it's still an E vs k plot, like in the one above, but with much more all at once!
@LRotheray So the 2D plots are a slice through these sorts of higher dimensional data sets.
Remember that bonding and anti-bonding stuff from yesterday? We can extract from our data sets the electron populations in differnet energy levels, and from there we can get the bond strengths at different times! https://t.co/aeDdHFToD0 https://t.co/YKPqN5yD2t
In the example here we can see the orbital distributions changing spatially after excitation, and that their bond strengths change as well (blue = weak, red = strong).
Actuall here we see the electrons behaviour change from insulating to metallic as time goes by! #phaseTransition Remember: metallic electrons are delocalised in a crystal, whereas in an insulator the electrons are confined to small regions.
I hope from that you start to get an idea of how powerful these techniques are, and why I find them so amazing! https://t.co/mZGYJkCk5b
@MySci_PK Actually the "bonds" movie I showed yesterday is from that project! The movie follows the rearrangment of atoms and bon during a structural phase transition. You can read the full story here 😉 https://t.co/aeDdHFSQNs
@Swifthom It can be very satisfying for sure!
@MySci_PK Here they are again: you can see the atoms moving (balck is for indium atoms) around and the bonds getting stronger. https://t.co/zHAFSlqKqq
For @MySci_PK and anyone else who wanted to see more of the nanowire bond dynamics: here is a nice artistic "still" from the movie. Indium atoms are shown in red, top layer silicon in yellow. The bonds that we change have that cool lava colour. https://t.co/fTciYFH89l
Nice! Seems like for most people thre is at least something about writin that they enjoy! Sorry for those who can't stand it 😅
Well it's been a busy week of #science! We've covered #emergence, #electronic structure, #writing and #ultrafast movies! I hope you've enjoyed the mixture so far! Is there anything you want to see more of? Let me know! https://t.co/ylH3zP74oi
Today I thought we could talk about science related stuff, but not directly research. What keeps you most busy apart from reseach?
@huebner_ralph I'm sensing some frustration here 😅
So it seems like admin/paperwork is winning in the polls. That's definitely true for me too at the moment having just moved country to set up a group: lots of paperwork! https://t.co/RJ4SUS98et
Still, there are a lot of exciting things that come with that: as an example we just got the keys to our new flat today, which means we can move out of our temporary accomodation🤩
Having some space you can call your own is a big step to feeling at home anywhere, at least in my experience. https://t.co/NdpBLfzc0M
Something that has taken quite a bit of time recently but that has also been very interesting for me is organising a #conference with some colleagues! @selenemor8 We even have a website now! https://t.co/OCyaqqzseQ https://t.co/mz2EqfmJ2R
RT @chrisw_nich: Well it's official, the #NGSCES conference 2022 website is now online! Looking forward to exciting talks and discussions o…
@selenemor8 It has been quite the experience putting it all together so far: selecting a location, discussing with the venue, working out a scientific program, looking for sponsorship, putting together the website... Quite the adventure! https://t.co/NY5Ca8ZNM0
@selenemor8 And fingers crossed we can actually have it in person too! Everything is still tricky with covid, but we're hopefull that in September things will be ok 😅
@selenemor8 The theme of the conference is very much what I've been discussing this week: emergent electronic phases. https://t.co/RSqt2LZvD0
@selenemor8 So if you or anyone you know might be interested, take a look or pass it on! We'd love to have you there! https://t.co/aSjicPL8X7
What have people's experiences of conferences been over the past year or so? I assume lots still online. How do you like online mode? https://t.co/L4UV6lblWx
And maybe even more importantly, what positives can we take away from our online conference experiences?
Should we be trying to have more hybrid style meetings in future?
There's been quite a lot of chatter about this paper recently, maybe you've seen it already? https://t.co/CBy3tVjTEo
@jageho @MySci_PK Must depend on whether we look with ARPES or diffraction 😉
Hope you all enjoyed #InternationalDayofGirlsAndWomeninScience yesterday! 👩🔬👩🔬👩🔬
I was moving house yesterday, so I wasn't even checking my emails let alone Twitter 😅 https://t.co/qscir8SIwY
As you can imagine, there is now lots to do getting the house in order so we can get settled in to our new life in Berlin.
I hope you've all enjoyed the science from this week, it's been a lot of fun for me! https://t.co/MLtS8u5wWp
And if you found it interesting you can come and find me over at @chrisw_nich for more ultrafast electron #movies. Bye for now! https://t.co/HKZJS3WjvY
[admin] HUGE THANK YOU to our amazing curator @chrisw_nich for a AMAZING week of science! 🥳 Catch Chris talking to us on our podcast 🎙️👇 short - https://t.co/vhMxUp0ck5 long - https://t.co/TdKS5gZmqo #UnderTheMicroscope #SciencePodcast #MaterialsScience #nanoscience https://t.co/QXLkTpPdfM
Yonatan Calahorra
[admin] "Breaking Barriers using Smart Materials" Please welcome this week's curator - @YonCalahorra and 👇podcast will tell you what is coming your way this week 🎙️🥳 #UnderTheMicroscope #sciencetwitter #materialsscience #nanoscience https://t.co/evyWqbtaf8
I'm very happy to host the account this week. It's almost midnight in Israel so I'll leave you for now with a gif describing both my research (multifunctional materials) and life as a new PI 😀 Let better and more peaceful times come soon ☮️ https://t.co/SCP6REt9qp
Hello everyone! I'm Yonatan Calahorra (@YonCalahorra) based at the Technion. My plans for (later) today are to introduce myself and my path in science. However this will have to wait since today in our department we focus on the sometimes forgotten topic of #safety .
This includes first aid and practical fire training so I'll be doing this quite soon! We tend to be caught-up in the pressure of producing results and it is easy to forget our first priority and responsibility of keeping ourselves and our colleagues safe https://t.co/GRCXMl7bXy
@LRotheray That can be quite a surprise :)
Aya, an MSc student in my group, battling the flames this afternoon - she succeeded! https://t.co/ruCoPtbHnD
A bit about me and my research - this was quite a ride so far, between (only?) 2 countries and 2 institutions, however through several scientific disciplines. Modern day multidisciplinary science has pros and cons (please share some thoughts) and I feel it personally too. >>
I'll start with a current challenge, in the last field I entered: magnetic materials. Recent magnetic force microscopy (MFM) of sputtered Ni layer are slightly strange: it was magnetized in-plane, however still shows stirpes of out of plane magnetization!! https://t.co/Qnbe8Zg3BK
This is a signature of materials showing "transcritical" magnetization loops, and we are trying to see how this is related to the structure (mechanical stresses?) of the underlying substrate. However, apart from the science>>
A lesson I've learned, going into a new field, is how much good peer-review can contribute. Even in rejected work, good and thorough PR can go a long way. In this case, we really didn't know what to make of the "strange" loops we measured, until the right term came up. https://t.co/bSuc9Emdq7
1/ Onwards and upwards! Or perhaps backwards (in time). I'd like to share parts of my journey from an BSc in EE to multifunctional nanomaterials and to pin-point the moment I was hooked on doing science - I hope you'll share yours (Refs. welcomed)
2/ I joined a nanoelectronics lab for MSc (Yaish lab) when the nanoworld was gaining much attention. My project which was about single Si nanowire FETs. Naturally, it evolved to something completely different within a few months - mechanical properties of suspended SiNWs>> https://t.co/6nR3c4dCl6
3/ It was pretty cool: the bottom-up NWs on the growth substrate looked like a spaghetti bowl, but you could still disperse individual ones, make them out in an optical mic. (despite ~ 30-60 nm in diameter) and use e-beam lithography and make suspended devices (Fig from paper) https://t.co/fJcUj7ndMW
4/ at that time, using an AFM to bend/deform such NWs was quite common and the scientific community was in turmoil: what happens to the elastic properties of nanomaterials? Experimental reports were showing different trends...
5/ It's a good time to remember a fundamental truth about nanomaterials: surface is much more important in nanomaterials. Think about the ratio between the surface area and volume of a sphere, it follows ~ 1/r. https://t.co/iYqJ5eJElc
6/ So people said that the SiO2 surrounding the NW plays an important role in the mechanical properties as it is actually a core/shell composite. That's true - but not the whole story and does not account for the results
7/ There is another interesting property of nanomaterials: they are much more flexible. As you recall, the NWs look like spaghetti, although they're made of brittle Si. That's because of their aspect ratio, which is very different than that of the Si wafer you use in the lab https://t.co/XF6kzGJoAh
8/ So these tiny beams, although made of a relatively rigid material, exhibited quite the deformation under an AFM tip - in fact, the elastic regime went from bending to tension - as evident from the recorded force curves that displayed stiffening (Fig from paper) https://t.co/BHEDqs7CD3
9/ So now we had basic beam theory (Euler–Bernoulli) and the addition of tension (great paper by Heidelberg et al) however, fitting the tension model to our measurements did not yield reasonable results (huge Youngs modulus for Si). that's when I got hooked on science https://t.co/4tJ6ikTbq9
10/ We realized that people disregard the residual stress in the beams, and that it can be detrimental, especially if you use the linear model. So we added a residual stress term to the model, and kaboom - model yields very reasonable results
11/ we found our wires belonged to two populations of Young's moduli - which was in agreement with their known crystalline orientations. and I know I have to keep on doing this thing :) find this paper here (it came a few years after the work was done) https://t.co/jZUoyIysLO
12/ So that's how I started really loving science, which naturally led me to venture into a new topic epitaxial NW growth (tomorrow) and that's also how I got my name next to Euler's in review papers 😆 (Fig from doi:10.1039/C6NR00863A) https://t.co/sddFahb6cp
@nlidgi It's this elusive moment when you realize that there's something going on, but you don't really know why - and after some thought you develop a theory that seems to explain it - I just love that cycle
@why_optics Thanks! That's definitely a major motivation for me
@nlidgi Thanks! What about you?
So far today: 1-1 w/students, we had a stimulating journal club, celebrated with cake a group-member's wedding (for those who couldn't make it), met a clean-room engineer to discuss a project. I managed to get closer to a proposal deadline without finishing it😀 how is your day?
But nothing will keep me from describing some past work about NW growth and how that relates to more current work! https://t.co/3cemt8sJI3
Since coffee is the fuel of science - how many cups do you drink daily? and what do you do to prevent spilling as you walk back to your seat/office? check this out https://t.co/VN2oS65YRC
[admin] "Breaking Barriers using Smart Materials" Longer conversations with the amazing @YonCalahorra of @TechnionLive is out now! Do give it a listen 👇🎙️🥳 #UnderTheMicroscope #sciencetwitter #materialsscience #nanoscience https://t.co/Ffu8qCruI4
@nlidgi @SebSaugout Nice one!
@SebSaugout I was similar, but gave in pretty fast in my MSc years
After switching to cappuccino style with froth I actually don't have this problem - it's a very efficient damper When I first started thinking about this problem I came across a paper or work that suggested mugs w/elliptical cross-sections would do it, but I can't find it now
It was around end of 2010 when I started my PhD. Prof. Ritter (Technion, EE) had an MOMBE chamber and I naively suggested we use it grow NWs (III-V). He said that actually another PhD candidate is interested in the exact same thing so we started - from scratch...
getting into a new field is very challenging (love to hear some experiences), and it took us a few good months just to get some nice looking NWs, like these guys (InP, gold catalyst) The problem was that just growing NWs was not good enough at the time to get good publications. https://t.co/RUUNqmB6yT
We weren't sure which way to go: interesting devices meant mastering more growth (doping, core/shell) and process (contacts). It took me full 4 years to get LED action going - here a single NW winning over 1000s of others in the race to emit light (the bright dot) https://t.co/ntI87ERX4G
So we realized we had to look into the more strange (esoteric?) results we'd observed. and so we did - which turned out quite fun! For example, we noticed that when we try to grow core/shell structures we get bendy NW (since we don't rotate the stage) https://t.co/S27q7PO7CQ https://t.co/lGXzNOEOSh
We also managed to grow nanoflags!! (also while trying to master core/shell) Achieved by forcing the catalyst to migrate down the NW "poll" and stop when it finds a crystal defect https://t.co/flkuC3Q73V https://t.co/hjYkde8icI
we also managed to manipulate the catalyst to a non-circular shape, forcing an asymmetric NW cross-section. Sometimes this resulted in octagonal(!!) cross-sections - totally unexpected (top view, showing non-hemispherical catalyst and strange facets). https://t.co/ar0Gdd0T5J https://t.co/wINBxV6GUG
towards the end of my PhD I thought long & hard about the directions I want to take (more "down to earth" or maybe more popular - aka fundable) and about how hard it is to jump into a new topic Which is exactly what I did for my postdoc 😆 https://t.co/yzkNJdlMTO
@ulrich_hofmann life is one big trade-off
We also have that plan today! https://t.co/0HUaMFQwmD
The non-drinkers are definitely a minority. Wondering whether they're discriminated against? 🤔 I think I'm unconsciously biased towards heavy drinkers :)
@LRotheray @chrisw_nich While presenting my research seminar to my current department (so quite important), I took a cup of black tea with me - big mistake! 5 minutes in I felt my thought dry as Sahara 😆 I remember thinking - get a grip, keep going. Somehow it worked and they actually hired me :) https://t.co/RR52MJyMbf
Recap of previous events: I was an EE graduate, studying nanomechanical properties and nanocrystal growth, looking for a postdoc. I found a warm home @Kar_Narayan_Lab, studying something new to me (again) - ferroelectric polymers, but back on the AFM. https://t.co/Un7GqjNETT
These years were eye-opening in many ways and resulted in further expansion of my interests - leading to my current research topic of "Magneto-Electro-Mechanical Smart Materials" where study of macromolecular arrangement of cellulose fibers lives alongside strained GaN LEDs 😀
We encountered some interesting challenges - one of them was performing piezoresponse force microscopy (PFM) on nanomaterials: in PFM, the AFM is in contact mode - not suitable at all for dispersed or vertical NWs since they move/break 😑 https://t.co/m7ZdXO2Kw2
I developed a "hacked" mode on our AFM to prevent that from happening - and we used it quite successfully to measure many brittle/nanostructured materials - including ceramics, good old III-V NWs and piezobiomaterials (Fig from 10.1039/C7NR06714C which I'm happy to discuss!) https://t.co/rx8YlmHOYQ
As an Elec. Eng., the concept of piezobiomaterial was really mind-blowing for me, and I found it super exciting. At some point my daughter and I grow sugar crystals and home which were later measured at the energy harvesting setup in the lab https://t.co/ay67EWMGob
I also had good times in @ProfRachelGaN group, studying piezoelectricity in GaN. They have A LOT of porous GaN activity going on there - and we became interested in studying nanoporosity effects on GaN piezoelectricity It's actually quite interesting:
porosity makes mater compliant - so in a piezoelectric this means you get a stronger response. Porous ferroelectric materials suffer a penalty due to pores interfering with poling process, however GaN is not ferroelectric, so this can actually be useful https://t.co/C9j64H2Bp7
I always make things complicated for myself, so I became interested in magnetoelectric composites - where one part is piezoelectric and the other magnetostrictive. And what is more natural than to fill porous GaN with nickel?
This completes the cycle - bringing me back to the thread from a few days ago, which began with MFM measurements of nickel sputtered on GaN (I hope you like what I did there😀) https://t.co/GWCvkLOX5Z
This also completes a research cycle, as these days I try to combine previous experience and knowledge about semiconductors, electronic devices, biomaterials, mechanical properties, piezoelectricity and magnetism into coherent research https://t.co/c2zs8ki9y4
If you're interested in any of this, drop me a line in a few months we're gonna have a kick-a$$ AFM which would be able to do almost anything you can think of (but coffee) and I'm always happy to collaborate!
@chrisw_nich @LRotheray Definitely
Did/do you listen to music while working in the lab? Did you ever get the feeling, after a long while of doing something, that the song is actually about YOUR science and not the songwriter's life? It used to happen to me quite often - please share with us your Sounds of Science https://t.co/yQFk7qxb5m
e.g. while aiming at mechanical energy harvesting applications from bodily functions like breathing, walking or just moving, I realized Sting should have been part of our team (@Kar_Narayan_Lab ), harvesting energy from every move we make https://t.co/NLCznUnyi2
the meeting of two musical titans was also very much about mechanics of materials ("Under pressure we're breaking") https://t.co/5YLwkkQbWf
I thank again everyone involved in this lovely channel and for the invitation to curate and share my perspective. Keep on doing good science and enjoy it! May we see peaceful and safer times soon.
[admin] Huge thank you to @YonCalahorra for a wonderful week of science! 🥳 Podcasts featuring Yonatan where he speaks about his science are here 👇🎙️🎧 #sciencetwitter #UnderTheMicroscope #nanoscience #materialsscience https://t.co/4FQ26PX1qk
Rebecca Cummings
[admin] "Argon Through the Looking Glass" Please welcome @becky_rbc for a wonderful week of science!🥳 Listen to the podcast to know what is coming your way this week 👇🎙️🎧 #UnderTheMicroscope #ScienceTwitter #nanoscience #materialsscience https://t.co/9IqcKL0fv6
Hello everyone! My name is Rebecca and I'll be taking over RealSci Nano this week. I'm a PhD student at @UofG_MCMP in the University of Glasgow and I can't wait to tell you about my research this week!
I'm going to start off by introducing myself a bit more, and talk about how I ended up doing my PhD! I always loved physics, and knew from pretty young that I wanted to study it at uni and ended up doing an integrated masters in physics at the University of Kent
It was there that I got into materials physics... kind of by accident. I was doing study abroad and missed the deadline for picking my masters project! I got assigned a materials project and very luckily, I loved it!
My project was looking for a new phase in bismuth ferrite using x-ray absorption spectroscopy, specifically extended x-ray absorption fine structure, or EXAFS. As part of my project I got to go to Diamond Light Source, which felt like finally taking part in “proper” science!
After that I decided to apply for PhDs because I knew I wanted to carry on studying, and because I’d really enjoyed my masters I decided to apply for materials projects. I accepted an offer from Glasgow, and that’s how I ended up where I am now!
Finishing up the day by talking a little bit about my PhD! My project uses electron energy loss spectroscopy (or EELS - remember this term! We'll be coming back to it later in the week) to look at the mirror coatings of gravitational wave detectors
I'll be going more into the specifics of my PhD later in the week, but suffice to say, knowing the structure of the mirror coatings can be really important to gravitational wave detectors, even though they're such a small component!
So although I'm a materials scientist, my samples are used for gravitational wave astronomy. That's probably my favourite part of materials, and spectroscopy in particular; how cross discipline its applications are!
I'll be talking about my research in more depth tomorrow but that's it for today, I'll leave you with a picture of the sun catching the buildings opposite my newly-returned-to office: https://t.co/EHBKbJEb6L
Today I’m going to be talking about my PhD project (and definitely not procrastinating writing my thesis…). So like I said yesterday, my project uses electron energy loss spectroscopy to investigate the mirror coatings of gravitational wave detectors
Starting with some context: why are the mirror coatings of GW detectors important? GWD are huge interferometers and they have have a bunch of mirrors inside them, not just at the end of the arms. The mirrors are made of silica...
and it’s crucial they absorb as few of the laser photons as possible, as this would lead to heating of the mirrors, and cause warping, and affect the sensitivity of the detector.
One of the things done to mitigate this is to coat the mirrors in multi-layer coatings, of high-refractive index and low-refractive index layers, but the coatings also contribute to the noise in the detector, particularly through thermal noise.
Fully understanding the structure of the coatings is the first step in characterising that noise so it can be subtracted from the GW signal, or eliminating it entirely!
So that’s the background for why coatings characterisation is important, I’ll be back after lunch to talk about HOW we do it!
While coatings characterisation can take many forms, I use EELS. Very simple, for any unfamiliar with it, use an ARM, shoot electrons through sample, how much energy they’ve lost will tell you what elements are in your sample.
The intensity of edge at the characteristic energy-loss is proportional to the amount of the element in the sample. We can also use high-angle annular dark field imaging to spatially resolve microscope images the heavy atoms will deflect the electron beam more strongly...
providing images with Z-contrast. Combining these two (with some clever maths) gives you spatially resolved images with absolute quantification, i.e. you can count the number of atoms of a specific element in any given pixel.
Going back to the coatings, it was known that there was argon in the coatings that wasn’t supposed to be there, and that there were little holes in the coatings. Using our technique we found they weren’t holes at all, but rather bubbles of argon.
Because we could count the number of argon atoms in the pixels we could work out the pressures and densities of the argon bubbles! And this research has applications outside GW detectors -- bubbles of noble gas form in the cladding of nuclear reactors in a similar process!
Took an unexpected break yesterday because it ended up being busier than expected! Thought I'd talk a bit about what my days have looked like this week as a final year PhD student!
Monday morning was very typical, admin and planning out my week! In the afternoon I was marking second year literature reports and then had another look at some code that suddenly broke on Friday
Tuesday was similar, replied to some questions about the marks from the students and made a little progress on my thesis. My code was still being recalcitrant so I decided to go work at a coffee shop in the hope that a change of scenery might help
And it did! Except I just copied the code into a new notebook and it suddenly worked... I didn't change any of the actual text so I'm still completely baffled by that one but I'm not complaining!
Like I said, Wednesday was a little busier, lost my morning to an unexpected appointment and then had demonstrating in the afternoon. I spent some time investigating potential postdocs and got stressed out thinking about the future 🙈
Today I have demonstrating again in the afternoon! Apart from that I'm adjusting a figure for a paper I'm working on after feedback from my supervisor and then I'm planning to make some thesis figures as I'll be in the figure making zone!
Fridays are always my least PhD-productive day. Our group does cake on Friday mornings, with us all taking turns to bring it in and early afternoons I have Italian class, as I wanted to do something apart from my PhD
Pre-pandemic I was part of a wind band but that obviously fell by the wayside, and I haven't managed to go back yet. I'll do some Italian prep in the morning around cake and then after see what odds and ends need doing before wrapping up for the weekend!
Thought I'd round up the week by talking a bit about spectroscopy itself! While the GW part of my research is very cool, it's the spectroscopy that I really love, so lets do a quick rundown!
EELS, my speciality and therefore obviosuly the best kind, is done in a microscope. Advantages: if you have a microscope it can be done in house, high spatial resolution, other characterisation can be done with the microscope's other capabilities
But it also has disadvantages, most notably that microscope samples are easily damaged by the beam and signal to noise is often a problem
X-ray absorption spectroscopy is the other spectroscopy type that I have some hands-on experience with. Work very similarly to EELS, except you're using an x-ray beam at a synchtrotron.
Fourier transform infrared spectroscopy is a type I don't have any experience with but works by exposing a sample to light and seeing what characteristic frequencies are absorbed
X-ray fluorescence is the last type I'm going to talk about, and it works a little differently, rather than looking at what is absorbed, you expose your sample to X-rays and then see what is fluoresced by your sample
All these spectroscopy types rely on the fact that the energy levels of different elements are different and unique, so you can figure out what elements are in your sample by looking for information at characteristic energies (543eV is the oxygen k-edge for example)
If you have a spike at 543eV, there's oxygen in your sample!
But why did I pick those two types of spectroscopy, when there's dozens to go around? Quite simple really, they're used a lot for one of my favourite applications of spectroscopy: conservation
No, not the ecological kind but rather conservation of artworks and cultural artificacts! For these types of samples, understanding their structure and how they've changed since they were created can give important information on how to preserve them
For really old samples, they can even tell us what they used to look like! For example, we know that old frescoes and the like used to be painted in vibrant colours thanks to trace amounts of these elements left behind
This is part of why I really love spectroscopy; although there are lots of varieties the principles are the same throughout, and they can be used for such a variety of things from helping observe the universe to preserving our history!
[admin] Huge thank you @becky_rbc for a wonderful week of science! Podcasts featuring Rebecca are here 👇🎙️ #UnderTheMicroscope #Sciencetwitter #materialsscience #nanoscience #WomenInSTEM #sciencepodcast https://t.co/Nl4qCQlSuH
Brian R. Pauw
[admin] Huge thank you @becky_rbc for a wonderful week of science! Podcasts featuring Rebecca are here 👇🎙️ #UnderTheMicroscope #Sciencetwitter #materialsscience #nanoscience #WomenInSTEM #sciencepodcast https://t.co/Nl4qCQlSuH
Good morning! https://t.co/JAHcWLANXf
Step 1, put on my aggro glasses… https://t.co/yYQ2CyHdXa
Step 2: commute. Today was a good day, nobody threatened my life! https://t.co/H5rM6BstFh
Step 3, coffee and a COVID test… https://t.co/Vu2CeH2oew
P.s. for all the high-tech at @BAMResearch, we do seem to have an inordinate about of trouble with ye olde elevator 😉. I am, of course, on the highest floor of the tallest building of the lot. (Disclaimer: this was last week, one elevator has since been fixed 😁) https://t.co/l21VgRZTs0
Good morning everyone, I am happy to be curating the @realsci_nano account this week. I normally tweet from the @drheaddamage account about anything and everything, but for this, I will mostly (but not excusively) focus on the nano- and science aspects 1/6
@drheaddamage I will also link heavily to my weblog ( https://t.co/oFYRvNhKj4) and my YouTube channel (https://t.co/guaMFL22aK). Both of these are not as active as I’d like them to be, but they do contain troves of useful in-depth information 2/6
@drheaddamage I suspect my colleagues find me to be annoying (although I hope I have gotten less abrasive more recently), I’m super stubborn yet chaotic, want to do everything right, and am hardly ever completely satisfied. This has consequences for my work. 3/6
@drheaddamage For example, I build and rebuild equipment that is never finished, I help develop data corrections that are never complete, I keep changing data storage formats, and I incessantly drone on about “standard error on the mean” – now a drinking game at @i22_DLS 4/6
@drheaddamage @I22_DLS This week, I will regale you with these stories in relation to scattering, alongside all kinds of other rants about scientific and Berlin life. If you’re into that sort of thing, do follow my @drheaddamage account. 5/6
@drheaddamage @I22_DLS One more administrative thing: I can’t promise to reply to every question, but if so, I could reply to questions using quote tweets if the question is of general interest, so keep an eye out for that! Let’s get started with the topic at hand: X-ray scattering! 6/6
With X-ray scattering, we can measure (quantitatively!) the nanostructure in materials. It’s good for measuring nanocomposites, nanoparticles, porous structures, metal alloys, catalysts, proteins, suspensions, membranes, batteries, basically everything with nano! https://t.co/cD5MqD8Mu3
So the previous curator, @becky_rbc already introduced X-rays which makes my life a lot easier, only the scattering part left! Let’s take a quick look at the X-ray scattering machine in our lab, the MOUSE! … https://t.co/a7lUmJX3F1
@becky_rbc (Video is from last year, more things have since changed on the machine..)
Despite the utility, it is not so popular. How often do you hear of X-ray scattering in your lives? 🧐
Looking good so far, maybe not as unpopular as I presumed!
There are advantages in being on the 7th floor…. https://t.co/1y70AXVJtS
Our scattering machine is quite a monster, both in terms of design as well as the publication rate… https://t.co/hW2WWl3XzW
We’ve also added a lot of nonstandard components over the years… but the biggest changes are software.. https://t.co/cCsVtu8ddx
Everything about this machine is now automated, even source and configuration changes. https://t.co/b0mGS6gMEf
That means we can now measure racks and racks of samples. These are the 32 that were on for the last 10 days. They’re mounted in holders designed by @S9Glen, using acrylic and paper holders we laser cut ourselves. https://t.co/SY3c65RROo
We’re constantly experimenting with sample cells. Here’s a new experiment (I found some swagelok valves) for a flow-through cap. https://t.co/6K3vY2OcdI
This is, of course, only possible thanks to the excellent in-house workshops at @BAMResearch. That low threshold to just pop into the basement to have a chat with the experienced engineers is absolutely priceless. https://t.co/x0T6acGNUC
X-ray scattering is cool because it’s old and new at the same time. The first treatise of X-ray scattering I found was from 1915 ( https://t.co/dBj14v1wvD), although earlier mentions of scattering of X-rays do exist ( https://t.co/Au9LJXRutI) 1/10 https://t.co/ObemOiJP58
A lot has happened since then on X-ray scattering, some of which I discuss in detail in my presentation here ( https://t.co/dtSvgNlXEh). But the field remains small. At the triannual scattering conferences, there are maybe ~300 participants. 2/10 https://t.co/bHjE3eid8S
In theory, X-ray scattering’s simple. A narrow beam of X-rays goes through a sample, and we look at the “splash” (scattering pattern) that emerges. In practice, it’s easy to get such a pattern on your detector when you stick a sample in, but that’s where it stops being easy. 3/10
The first problem is isolating the real scattering effects from your sample, from all the other – for lack of a better word - “shit”, that you get on your detector from the imperfections imposed by practicalities of reality. Part of this is the data correction step. 4/10 https://t.co/P1Jg1DCCaD
Together with many colleagues, I’ve been working on perfecting this data correction problem for years, as summarized in this talk: https://t.co/0ricmoEmxc . We’re still working on fine-tuning the last few corrections, but most are available as part of @dawnscience 5/10
@DAWNScience The other part is to take practical steps to clean up your scattering pattern before you collect it. That’s what we did when we bought and adapted an already heavily customized @xenocs_news instrument four years ago. 6/10
@DAWNScience In trying to improve this already custom machine, we started changing hardware components and the control software. The data processing software that came with it was unused from day 1. More on our reasoning for that in a later thread. 7/10 https://t.co/9Xp9VZZGe1
@DAWNScience So now we can get a pretty clean signal to begin with, and then extract only the scattering from the sample using the extensive data corrections. Now comes the analysis, the most painful part of the whole process. This almost invariably needs to be customized to the sample. 8/10 https://t.co/9uMr4FgNGG
@DAWNScience I suspect X-ray scattering is not so popular because we’re not producing cool images such as false-colored electron microscopy images, or the sweet copper-toned scanning-probe microscopy images. Moreover, however, I the analysis process remains a bit.. “mystic”. 9/10
@DAWNScience That mysticism comes partially from experienced hands being able to “read” scattering patterns. I’ll show you what the analysis looks like after a brief intermezzo on authorships on our instrument’s papers. 10/10 https://t.co/RmvEBZrB7O
P.s. if you have any questions at any time, please don’t hesitate to ask!
To top off the day, after admin, meetings and some Python calculations, I have to rewire (mirror) a connector to ensure I have the correct assumed wiring for updated MOUSE 🐭 stepper motor controllers. All in a day’s work. https://t.co/dBZLC4doQH
Quick test, yep seems to home fine. https://t.co/GxMpB5KWSi
Woop. https://t.co/XMGtlshf9I
Meanwhile, my colleague has set up a nice calibrant in the MOUSE 🐭, this is X-ray scattering with the detector up close and all the way in the personal space of the sample (50mm distance) https://t.co/9ZdXvOhgN1
@ToolWfh Good question. We have an artificial digestion set in our laboratories so we can see what happens to nanoparticles when you ingest them. For injections, I guess it’s dependent on if you inject in blood or muscle, but I guess these environments could be simulated as well.
@ToolWfh That would be the domain of the BFR (risk assessment institute) though, they do extensive tests on toxicological effects of nanomaterials. Our group occasionally works with them for artificial digestion experiments.
@ToolWfh SAXS can measure proteins, but isolated and purified in solution, so you know what you are looking at. Even if we could stick a complete body in, you wouldn’t be able to separate the nanoparticle scattering from all the other scattering from there… So we have to simplify.
@ToolWfh You could measure nanoparticles (and possible size changes) when immersed in blood plasma, for example. For subcutaneous injections it’d be a bit harder to find a suitable simulated analog though.
Alright everyone, I’m clocking out and heading home. See you tomorrow!
@svenja_lohmann @becky_rbc Fortunately, our instrument works fine in high vacuum, not ultra-high vacuum. This makes many things easier: I can have plastic-coated cables and plastic holders in the MOUSE, and non-UHV variants of stages and plates, and mostly, no baking required! So no need for foil :) https://t.co/JLRWugs1SG
Good morning everyone. Today is home office day, I’m continuing work a custom analysis for a particularly challenging but beautiful measurement series we did on @laHannue’s composites. https://t.co/TAr75AwKIU
@laHannue .. and I just found out my analysis code didn’t apply one of my minimum uncertainty estimators in this case (I disabled the rebinning step that takes care of that here for some reason). It’s a problem that’s been bogging me down in this script for days!
Time for a mini 🧵: Helped by our instrument, the MOUSE, @s9glen and I are contributing X-ray scattering insights to a whole host of studies, the full list of which is on the MOUSE’s Google Scholar page: https://t.co/x6Fvp21sl0 1/5
@S9Glen You’ll notice my name doesn’t appear on many of these. We decided early on to follow @DFG principles as best we can; only awarding authorships to those who made a significant scientific contribution to the paper. 2/5
@S9Glen @Dfg While I’ve set up a lot of the methodology around the instrument itself, the majority of the activities involving collaborative projects are led by @s9glen, who spends an ungodly amount of time building and composing custom analyses for scattering patterns.
@S9Glen @Dfg I occasionally contribute a little insight to these, but not necessarily what I would consider a “significant” scientific input. Hence I’m not on many of the papers, but I still consider the MOUSE paper output part of our accomplishments. 4/5
@S9Glen @Dfg As will become clear later, I am not a fan of such nonsense as “researcher” metrics (h-index, citation scores, impact factors), and sheer number of papers doesn’t excite me. What does is exploration – finding out what’s possible, so let’s move on to a simple example! 5/5 https://t.co/ogSKV90h5p
@RKarsthof @svenja_lohmann @becky_rbc Good question. That much depends on the energy of the X-ray photons, but “X-ray” covers a whole range of energies. The ones we use have photons of 8 and 17 keV (emitted by copper and molybdenum targets, respectively). For copper, 1m of air would halve your flux. 1/n
@RKarsthof @svenja_lohmann @becky_rbc So by evacuating, we lose fewer photons through absorption by air. A second phenomenon is scattering by air, when a beam of X-rays passes through air, interaction with the suspended molecules scatters a fraction, which muddies our sample signal. 2/n
@RKarsthof @svenja_lohmann @becky_rbc We can subtract such parasitic background again from our measurement, but the counting noise (uncertainties) adds if you subtract the signal. So having any background decreases your signal-to-noise ratio rapidly. That means minimizing windows and air paths.. 3/n
@RKarsthof @svenja_lohmann @becky_rbc This is investigated in detail in appendix F of our last monster paper: https://t.co/QS7G2trUPj . You’ll still see many instruments with air paths or windows, but we chose to minimize our background for the sake of improved statistics with a continuous vacuum path. 4/4
@RKarsthof @svenja_lohmann @becky_rbc 5/4 Another option would be increasing the energy of our X-rays, higher energy interacts less with air (or any matter). There we have other problems: the efficiency of both monochromatic X-ray generation, focusing, collimation and detection all drop off. Additionally, to
@RKarsthof @svenja_lohmann @becky_rbc 6/4 measure the same size nanostructure in your samples, you need to measure to much smaller angles. That requires even better beam parameters and exponentially longer instruments (as both collimation and flight path need to extend greatly).
@RKarsthof @svenja_lohmann @becky_rbc 7/4 You then end up with high-energy X-ray scattering instruments of hundreds of meters long, exclusively found at synchrotrons (better beam parameters). These machines have a niche purpose, but given the difficulties, it’s easier to stay with lower-energy photons (fin].
@RKarsthof @svenja_lohmann @becky_rbc Thanks :). And diffraction is just X-ray scattering applied to regular structures. We see both. Check out this beauty measured with both sources in many instrument configurations. We see another energy-dependent effect here: we have an additional fluorescence bgnd with moly! https://t.co/HdUHxB18iF
@RKarsthof @svenja_lohmann @becky_rbc This also demonstrates that our extensive data corrections work well in the XRD region, and gives you diffraction data on absolute scale with uncertainty estimates and *no* background. Any remaining amorphous diffraction/scattering signal originates from your sample itself!
Trying to wrap my head around the effect of inter particle interactions to SAS patterns is doing my head in, so let me take a break by showing you how SAS analysis usually pans out (after many weeks of careful deliberation and trying (and failing) several approaches):
Let’s start with one of the easier examples that @s9glen and I contributed to: a study by researchers of the @v_saggiomo group of @WUR on special optical properties of gold- and silver nanoparticles in 3D-printable composites. https://t.co/htQL7fyrFs
@S9Glen @V_Saggiomo @WUR This was relatively easy from the X-ray scattering viewpoint, but still threw up a few interesting questions. So here, the researchers put gold and silver nanoparticles inside a polymer. Then, they would print that polymer in a filament-fed 3D printer into funny shapes. https://t.co/sTIAgrqfmj
@S9Glen @V_Saggiomo @WUR We measured the scattering patterns of the silver nanoparticles suspended in their initial liquid, the silver nanoparticles in the PVA polymer, and the silver nanoparticles in the PVA polymer after printing. After correction, we get nice wide-range X-ray scattering data. https://t.co/N1Avn3li9q
@S9Glen @V_Saggiomo @WUR So now we can get to the tea-leaf reading aspect of X-ray scattering: for those familiar with the method, we can already read off some information off of these scattering patterns: The shoulder at low Q tells us of one population of particles, https://t.co/Py2Cfa7qlJ
@S9Glen @V_Saggiomo @WUR the lack of oscillations tells us they are polydisperse in shape or size, and the absolute scattering level tells us it’s a realistic amount of scattering assuming silver in liquid (so we didn’t fuck up on the data correction step or the phase assumptions). https://t.co/QKDxl9AmOj
@S9Glen @V_Saggiomo @WUR So far so good, but wait! There’s a second hump in one of the samples, is that a second, independent population of smaller particles? It looks to be the case, so let’s dig deeper and actually analyze these patterns using my McSAS software (https://t.co/NTj6NMWEJ0). https://t.co/h5xP0QHFLj
@S9Glen @V_Saggiomo @WUR This software needs an overall shape assumption (here spheres), and then spits out the size distribution required under that shape assumption to get this scattering pattern. Here, there’s no need to assume a gaussian or lognormal, monomodal or multimodal distribution. https://t.co/NOPs4XxBuB
@S9Glen @V_Saggiomo @WUR So for these three measurements, we see: 1) a monomodal population of (silver) particles, 2) a bimodal population, silver particles and something else, and 3) a monomodal population of silver particles again. What’s going on here? https://t.co/HcyRJQv8nZ
@S9Glen @V_Saggiomo @WUR Well, we first double-checked to make sure we didn’t make a mistake in measuring or correcting our data. Then we thought and discussed with the other scientists, and after some time, found out there’s a stabilizer added to the particles… https://t.co/IoTYPRBlzS
@S9Glen @V_Saggiomo @WUR Stabilizers are typically organic molecules added to nanoparticle suspensions to make sure the particles don’t stick together immediately. In this case, the authors had added a large excess of PVP https://t.co/Nb7Sl3wTtb .
@S9Glen @V_Saggiomo @WUR In the liquid sample, this PVP is swimming freely around, and has a low contrast compared to the liquid. When mixed into the PVA polymer matrix, however, it looks like this PVP is phase separating out into small globules alongside the particles → there’s our small population. https://t.co/5i51YN2asr
@S9Glen @V_Saggiomo @WUR Then, when melting the entire composite at much higher temperatures during printing, these PVP particles dissociate and mix with the PVA polymer. At least that’s our working hypothesis, not contradicted by the data (best we can do without deeper study). https://t.co/tuLuTG9IKh
@S9Glen @V_Saggiomo @WUR (An alternative is that at higher temperature, the PVP globules meld together to form a few large globules, I did not test for this explicitly)
@S9Glen @V_Saggiomo @WUR During all this, the silver nanoparticles are mostly stable, although they do start clumping together a bit leading to an upward shift of our population. Apart from dimensions, we can also get volume(or mass) fractions out of this data, thanks to our absolute-scaled intensity.
@S9Glen @V_Saggiomo @WUR In this case, there were no surprises, the silver was in there at the expected concentration, and the fraction of PVP also did not contradict our assumptions. But abs-scaled data is essential for double-checking assumptions and interpretations! https://t.co/dftVgraFko
@S9Glen @V_Saggiomo @WUR So now you know what we can do with X-ray scattering data (for easy cases), but is it really true or did we just get lucky here? Why does it sometimes not work? Big questions worthy of upcoming threads… https://t.co/aK0gInqXAy
@psobolewskiPhD @S9Glen @V_Saggiomo @WUR Yes, sorry, I probably didn’t update the link. You’re right with the GH page for the original McSAS https://t.co/1krtjHkezG and the refactored one I’m working on these days (no GUI but yes awesomeness): https://t.co/dfmXE4Gczk
RT @_SuSiSe_: This pretty much sums up our life at the #SAXSWAXS beamline at @ausynchrotron @ANSTO too! Isn’t it wonderful what a broad ran…
Hey that’s not too bad, much better than my assumptions! Thanks for joining in in the poll, everyone! https://t.co/N4FzxXEKQi
sometimes, things aren't that easy. For example when systems get dense. Here's an example of my current problem: the blue curve is what we got for dilute systems, the red curve is what we have in denser samples. Interparticle interference starts mucking things up! https://t.co/U1kinHHClp
There are many analytical descriptions for this so-called "structure factor" (interparticle scattering), but they all invariably suck at describing the behaviour accurately. https://t.co/GgdAXgS5pQ
I've spent the morning isolated from my e-mail double-checking my structure factor equations with those from ancient literature. This is a relatively recent write-up from 1984, and yes, it's all those equations smooshed together: https://t.co/InXYJJCiKA
The resulting effect... is less than impressive and doesn't look at all like the actually measured red curve. So back to the drawing board for me, I'll have to come up with another solution to this particular story. https://t.co/1OS9P0TKl4
@V_Saggiomo @S9Glen @WUR We do! More specifically, my colleague @AnjaWaske has one 😁
RT @HamishY_Sci: Excited to be advertising a new PhD studentship! It will involve time with my wonderful group at @UoBChemistry, and time a…
Hey everyone, my brain is absolute mush after staring at equations for half a day. I’ll check out for today, tomorrow we’ll go back to the lab for some soldering and robotics, and hopefully I’ll be able to explain what we’ve done to organize our MOUSE 🐭 measurements as well!
From a trip last year. https://t.co/E5AgiJlq5X
And in case anyone is looking to have an uplifting background image on their iPhone… https://t.co/qBcEKsB271
Good morning everyone. Just getting ready to start the day, today will be some soldering work on the v.2 motor controllers, I’ll have to help a colleague troubleshoot their Arduino network connections, prepare a short NeXus presentation/demo for NFDI, and other random stuff.
It’s days like these that could make me feel wholly unproductive at the end of the day, because I’ll have worked on a lot but not finished anything in the end. Add to that the constant doom from the newsfeeds, and it’s easy to end up feeling powerless and deflated.
There’s also no way that I’ll be able to do any sort of “intelligent” work today, work that would require a few uninterrupted hours of deep focus. It’s been too long since I had time like that, interruptions include, e-mails, teams messages, meetings, mail deliveries, calls
Days like these I call “headless-chicken days” since I’m running around extinguishing small fires like a headless chicken. What these days are for are to make sure everyone else is free of blockers and can continue their tasks. Not my official job description, but still needed.
Check out this absolute beauty designed by a student assistant working with me, and made by our fabulous basement workshop! It’s for a belt drive for rails, with a helical 5:1 reduction on the stepper motor.. https://t.co/LkNehKv2q4
First headless chicken task today, measure these small ferrules accurately so we know which style graphite or graphite/vespel ferrules would fit for glass caps… https://t.co/1CvjrhDr2K
[admin] "Everything SAXS - Big Methods for Small Studies" Extended conversation with the amazing @drheaddamage is out now. Check it out! 👇🎧🎙️ #UnderTheMicroscope #sciencetwitter #materialsscience #nanoscience #sciencepodcast https://t.co/b6nOKvbqbo
Just in case one of you has a micrometer (more accurate than calipers), here’s how I was taught to hold them by the workshop staff at NIMS in Japan. https://t.co/pnic8awxxf
@Janwen17 This one is a bit chonky, and sometimes two hands are necessary. The one-handed trick frees up a hand though 😁
Calipers should be used like this, and both calipers as well as micrometers should be mechanical versions, the battery-powered ones are always out of battery at the worst moments! https://t.co/oFv1d7mPAp
So, for future reference, here’s the dimensions and angles of the ferrules. Now to find out what LC manufacturer’s they’re closest to or compatible with… https://t.co/NN4TRM6QaV
Because of course, GC (not LC, sorry) ferrules come in different shapes and sizes, separated by manufacturer. I know from long ago, that there are ferrules (HP/Agilent perhaps?) that also fit in Swagelok connections. But I need to check before ordering the wrong one.
Meanwhile, I walked past my v.2 motor controllers with a multimeter, and noticed the resistance is a bit high between the end of the casing and the earth conduit, so I’ll need to improve that with a central earth bus later as well. It’s earthed to the central plate only at the mo https://t.co/hkViXX4yFk
Meeting time…
Meeting over, back to business.
Solved the Arduino problem of my colleague, and now, after wiring the earths, I’m soldering the motor connections. I can only do a few of these per day, shaky hands… https://t.co/JvyuePVtfe
At the end, not a terrible job for these three. It’s a bit annoying to have mounted the connectors at an angle, and I shouldn’t have fixed them in place yet for better accessibility, but ah well, compromises. https://t.co/Qman8JwxWd
After checking for shorts, time for testing (again) https://t.co/HJjsgOtWgF
Now we’re always interested in automating sample prep and sample development, which is why we’re playing around with robotics too. Recently, one student finished his https://t.co/4ASfUWWicg. on our robot, making and quantifying drop series on slides! 1/2 https://t.co/TOa7PPEvbs
Learning these things will allow us to prepare more consistent sample series, and explore synthesis parameter spaces. This robot consists of normal lab components linked via EPICS, and controlled via a jupyter notebook.
Now that robot arm we have is a bit tiny with small reach, so our student assistant is building some rails for it, and it’s already looking awesome 😁. https://t.co/JfC7eq7SIj
It’s not finished yet and probably has issues needing to be resolved, but I think it’s going to work and worthy of the OverEngineered label 🏷. That’s the second reason I’m working on motor controllers. Primary reason is to replace our working horse v.1 I made earlier. https://t.co/lAfGb3xaxf
V1 had straight connections that work fine, but our vacuum feedthroughs mirror the connections so I need to mirror them back. Once that’s done, I can test our grazing incidence sample stage for GISAXS: https://t.co/sm5rpQ76z3
With this stage, we can measure layered surfaces in SAXS, which gives beautiful patterns but remains a very young field with its own challenges. The main problems with GISAXS are the largely unknown data correction steps, and the much more complicated analysis.
GISAXS now is where SAXS was 20-30 years ago. Still in need of thorough development but a lot of good work is already underway. Besides GISAXS, the new motor controllers will also make using my USAXS easier. https://t.co/9FnW22DO8i
USAXS stands for ultra-small-angle X-ray scattering; measuring smaller angles, we can measure larger structures. I’ve been building machines for this for a while, here’s one we tested at @i22_DLS: https://t.co/RG7J4ggz3J
@I22_DLS We also recently tested this in the MOUSE 🐭, and it seems to be working just fine! I’m not happy with the cable salad though, so that led to me starting on v.2 of the motor controller to help clean that up. The USAXS then allows us to measure structures up to 2-3 micrometer!
@I22_DLS With our normal SAXS/WAXS operation in the MOUSE, we quantify structures with dimensions from ~0.5 Å to 300 nm, so the USAXS adds a nice decade on top of that. It’s a much more tedious scan to measure these ultra-small angles, but it’s more information and that’s always good.
Was developing a headache, and then I realized that in my headless-chicken-run, I’ve not had a drop to drink nor lunch. So I’ll head home now and call it a day! Some tasks were achieved, but I haven’t had the chance to tell you about data management yet… Sorry!
3D-printer is printing, MOUSE 🐭 continues measuring, I can go home in peace 😁
Office in sunset 😅 https://t.co/5a3yEN93HK
For the ride home, I usually cycle another route, one that takes me over the Schlossstrasse in Berlin. Cycling in Berlin now is like cycling in the Netherlands in the 1980s. There’s a modicum of infrastructure, but it’s still shit, full of cars and dangerous situations. https://t.co/1PjVDSZrGS
@gudrun_lotze It’s woefully inadequate. It’s a wonder nothing much in terms of accidents has befallen me yet. (Knocks on wood) https://t.co/4j3OZWTmXZ
So I’ve two main hobbies, both to do with the sea: sailing and diving. I don’t have the funds nor the time to buy my own sailboat, you’d need a better paying job for that, but I do get out occasionally. Last year, I got my SSS, the German equivalent to an offshore license. https://t.co/acvJkCzPXu
The only higher license on the German scheme is the SHS, the ocean skipper license. That’s a purely theoretical addition, adding astronavigation into the examination. I’m working my way to that, but need a total of 2000 miles as skipper for that. So if anyone …
So if anyone has a sailing vessel they’d like me to skipper, please do get in touch! I can sail anything including Mediterranean and Baltic, English Channel, etc, I’m only not allowed to earn money for ocean crossings without the SHS. 😁
@Goerlitzer_etal That is also true, holidays will have to be long and dedicated to exploring a particular segment of coast. If remote working catches on a bit more, that would also make it possible to utilize those stormy days stuck in port on extended trips.
As for diving, I’m an AOWD with some specialties thrown in. I’ve recently assembled my own backplate and wing BCD, and a DIR regulator set. That takes me to amazing places on various holidays (can’t find my videos on that now, unfortunately).
Both these hobbies are filled with old white men, unfortunately, and could do with a lot more diversity. I hope I live that long to see change… https://t.co/hZLofTi6mm
RT @Sherif_A_Tawfik: @RealSci_Nano I also followed this paper with another, https://t.co/Hjfch9u5CR, which have further calculations on squ…
@ehmke_pohl @drheaddamage Hey congratulations! I’m sure you’ll be crossing oceans in no time, and every step towards that is worth celebrating 😁. The RYA licenses are said to be a lot more practical than the German ones, but anything that gets you out on the water is worth it.
@ehmke_pohl @drheaddamage Very German indeed, it’s very heavy on theory, whereas the practical exam was rather limited and didn’t take more than a few hours to examine four participants. Besides that, the examiners were also very restricted in their freedom to judge. It’s all very administrative…
@ehmke_pohl @drheaddamage Good thing that we had a teacher/school who made us learn a lot of extra practical skills, rather than only focusing on the exam requirements. Finding a good teacher made it all a lot more enjoyable. Also, he didn’t mind me messing with the electrical installation on board :).
https://t.co/P2DVTUS8m5 https://t.co/ZSrrEmfBin
Since the beginning of the technique, there has been a lot of skepticism, and rightfully so. I remember many papers stating that “SAXS dimensions are always bigger than TEM dimensions”, or papers explaining away differences with handwavy arguments. 1/7 https://t.co/EsdwqwfQAa
This could be part of what gives X-ray scattering an occasional bad rep: even when it ostensibly works, the results aren’t comparable to other techniques, in particular to TEM, so why bother? However, when tested against standards, it matches! What’s going on here? 2/7
Part of this was due to the (continuing!) poor data correction standards, more on this later. Another problem is the inherent complexities in accurate TEM size distribution determinations, which an electron microscopist can explain far better than I. 3/7 https://t.co/f6Hl0d1wBU
But a main problem is that X-ray scattering gives a signal that closely matches a volume-weighted representation of the size distribution. (typically monodisperse) standards don’t have this, and voila, the size match between TEM and X-ray scattering is near perfect. 4/7
But add a bit of polydispersity, and all intercomparisons must be corrected either one way or the other before comparing. One example of not enough effort in SAXS analysis, coupled with handwavy dismissals of discrepancies can be found in this paper ( https://t.co/V01owZTQIM) 5/8 https://t.co/RbXl7X4IoE
This work has 1) no indication of data correction being done 2) fits that don’t fit (lacks dispersity) 3) hand-wavy excuses about volume weighting skewing their results. This is unfortunate, because a little bit of effort would’ve brought these results in line. 6/8 https://t.co/6W4DAXQGqB
But as it is now, it looks like another piece of evidence that SAXS sucks. There are unfortunately many papers like this, I suspect the main issue is that not enough care is given to the experiment, probably due to juggling too many tasks and papers, or being overloaded. 7/9
With microscopic techniques, if you don’t put enough effort into them, you still have a reasonably correct resulting projection (image). With X-ray scattering experiments, however, if it’s not done with sufficient care, the answer is plain wrong in unpredictable ways. 8/9 https://t.co/uV8F1B4Rjb
And that segue’s nicely into my next topic: what has to go right for an X-ray scattering experiment to work?
P.S.: Want to be a co-author? if you’re interested in knowing how much the human factor affects data analysis of small-angle scattering, why not join in our data analysis round robin experiment? Check out the coolness here and tell your friends! https://t.co/XJbaiCmISV
@ehmke_pohl @drheaddamage Sounds amazing, what do you normally sail? Sailing the bigger boats certainly helps to refine those harbor techniques. With smaller boats it’s so tempting to just use hands and feet to fix imperfect maneuvers, with bigger boats there’s no chance that’ll lead to anything good 😅
If you come across me on the street, chances are I’m wearing headphones. Music has played a large part in my life, it helps me (re)focus some times when I’m getting stressed, and it entertains when cycling. I’ve got a pretty eclectic mix of styles, from classical to death metal
I usually get really carried away with well-recorded songs, for example check out this one: https://t.co/W3kDhHRGvO . Our library is great for finding new songs, I can borrow random CDs for free, as many as I can eat!
Also check out this raw beauty from Neil Young: https://t.co/tz3JnkfuKj , apparently the guitar player was so stoned he played the wrong chord, but it works out fantastically.
Roger Waters also holds a fascination, pretty much ever after the split from Pink Floyd after the amazing “the final cut” album. His songs contain nice political commentary in the songs: https://t.co/VeXwyIV98n
By the way, for anyone interested in the absolutely best data format ever (HDF5/NeXus), there's a conference starting on that later today. Registration and joining's still possible I think: https://t.co/mguQ0DRudf
RT @RealSci_Nano: By the way, for anyone interested in the absolutely best data format ever (HDF5/NeXus), there's a conference starting on…
🧵 How can you organize an X-ray experiment to avoid most of the mistakes? That’s something @s9glen and I recently wrote an absolute monster of a paper about (still a good read though!). That paper is here: https://t.co/hKYM8ordZg 1/
@S9Glen (apropos, that paper comes with a 20+ GB repository of data and jupyter notebooks used to calibrate, analyze and visualize: https://t.co/uZmFRAtWEI)
@S9Glen This paper takes an unconventional “holistic” approach: for an X-ray scattering experiment to go right, you must do good 1) sample prep, 2) data collection 3) data correction, 4) data analysis and 5) combining X-ray scattering results with those of other techniques 3/
@S9Glen Any imperfection in any of these, and your X-ray scattering experiment is unreliable. Do all these right though, and the results can be very gratifying. And that’s what we’re aiming for, absolute perfection.. (cc. @I22_DLS and @timmy864 for their help towards this) 4/ https://t.co/eZlTmPgV45
@S9Glen @I22_DLS @timmy864 Step one is the sample preparation. Frustratingly for our materials science colleagues, it’s not easy to say what samples will and won’t work. I made a video that discusses a few details of sample selection for scattering: https://t.co/wxHCvWexHv 5/
@S9Glen @I22_DLS @timmy864 Secondly, we have the data collection. We now collect an enormous amount of data in an automated way, measuring multiple repeats of 600s exposures of every sample in multiple instrument configurations. For a normal sample we typically do 600s * 33 repetitions per sample 6/ https://t.co/8M0PXLTb52
@S9Glen @I22_DLS @timmy864 … this can rapidly increase though if we do special measurements or use multiple X-ray sources. These 33 measurements come with 33 flux, beam and transmission measurements to monitor instrument and sample stability, which are stored as part of the measurement metadata. 7/
@S9Glen @I22_DLS @timmy864 And we do all this for up to 48 samples per two- to three-week “run”, so that’s easily 1000 measurements. We’ve adopted the NeXus format for storing all this data in an archival, easily understood and very comprehensive format in an HDF5 container. 8/ https://t.co/XUbpY1rzrq
@S9Glen @I22_DLS @timmy864 Note, by the way, that this is far from the “standard” in the field (if there is such a thing). Many instruments and places still use clicky interfaces to start single measurements, doing things right on those machines is a royal pain in the ass. 9/ https://t.co/mc7p3KkyIV
@S9Glen @I22_DLS @timmy864 In step 3, we take these NeXus files (containing the repeated datasets) and process them using the corrections implemented in the @dawnscience software by @jacobfilik together with @timmy864 over the course of several years. Here too, things are more extensive than normal. 10/
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik For example, nearly all the datacorrection steps are done on the 2D scattering images, before in the end they may be converted to a 1D scattering curve. We do this so that if there is alignment in the sample, we can get precisely corrected data for that in 2D. 11/
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik I am very proud of the data corrections, it has been a long journey, but now we have a universally applicable data correction sequence. Works for every sample we throw at it, both on the MOUSE, but also at the @i22_DLS beamline and lab instrument too! https://t.co/7Wa1HGdH2s
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik Given the success of that, I wish we could convince other X-ray scattering instruments to use these methods, but a combination of (perhaps) pragmatism and “not invented here”-syndrome seems to be blocking its adoption. Scientists can be surprisingly conservative! 13/
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik Also the “argumentam ad antiquitam” is one I hear often: “we’ve always done it like this…”, to which my response in most cases is “yes, and it’s always been shit”. But I digress.. This data correction is now automatic with us, no human input needed, no knobs to twiddle. https://t.co/8CVVGkkCel
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik So given our “as good as it could get”-data now, we move on to step 4: analysis. This is not automated by far, and it is our bread and butter. This is where we spend 80% of our time if not more, trying to find a model to fit the data with. That model needs to do two things: 15/
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik 1) the model needs to be able to describe the data precisely. That’s not always easy and sometimes requires quite a few components, and 2) the model needs to be physically realistic for that sample: the model components need to be justified with e.g. TEM images. https://t.co/UHRWSk2H6N
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik coming back to that last point, it’s no use having a fractal model to describe your data, if there are no fractals in your sample. Don’t use cylinders if there is no evidence for them, etc., etc. Your model must be in accordance with the physical structure of the sample. 17/ https://t.co/bhRliYE0Af
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik one problem with X-ray scattering analysis is that I can get many models to fit the same data. However, just because it fits your data doesn’t mean it’s the right model. X-ray scattering data doesn’t have a lot of information, so a lot hinges on using the correct model. 18/
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik And that trips people up. Here’s a paper that argues that since a disk model fits the data better than spheres or cylinders, it must be the right model: ( https://t.co/KjQsiiIevW ). McSAS tells me that the shape and size distribution are inherently linked. 19/ https://t.co/79vNsHJObz
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik That means that I can get a perfect fit with e.g. spheres, but also with cylinders (see images). The difference then lies in the size distributions. Both fits are equally valid, so you’ll need to supply extra evidence (for example TEM) to validate the shape assumption 20/ https://t.co/r5ui4ZgcBH
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik So in the end, for SAXS to be any good at all, all these aspects need to be flawless, from sample prep to interpretation of the analyses. And there’s no magic solution that fits them all.. That’s the challenge of the X-ray scattering field, and it’s what’s keeping us very busy! https://t.co/QZkS67peC0
@S9Glen @I22_DLS @timmy864 @DAWNScience @JacobFilik And with these ridiculous machine efficiencies we’re reaching now, we’re trying to solve many dozens of independent analytical challenges every year. It’s honestly exhausting, and we really need more people in the team to help analyze and interpret these masses of data. 22/EOF
@ehmke_pohl @drheaddamage Sounds like heaps of experience, and loads of fun 🤩. Feel free to contact me if you need some extra battle-hardened crew 😁.
Now in an online workshop on NeXus for a German NFDI (national research data infrastructure) group… Fortunately it seems like NeXus/HDF5 is gaining ground there, which makes sense as it’s a stupendously useful format.
Another day ending in brain-mush, the NFDI workshop was - for once - an interesting meeting! The problem with having to cover all aspects on our technique, is that I have to keep up to date with a wide variety of aspects, then picking which one is in most need of upgrades… https://t.co/whRUgqRI77
And finally, of course, doing much of the upgrading by hand myself. It’s a lonely life sometimes..
Good morning everyone! Today I’m in the office again, joining the NFDI workshop online (this time on https://t.co/E2vt8udVcE). I’ll be presenting briefly on our data storage and management system, to see if there’s anyone interested in what we’ve accomplished so far.
Like many of you, I’ve problems with overcommitting to too many projects, leaving me exhausted and unable to do many things as well as I’d like. The pressures to join projects is enormous, both from up high as well as from a FOMO perspective. 1/
Whether or not I have mild ADHD, I don’t know. But this video on learning to say “no” certainly resonated strongly with me https://t.co/hMhtrk7kmL 2/
Another very important tool is to realize that your research is a job, and as such should not demand more than normal working hours. There are many voices out there that push you towards spending a significant chunk of your own time on science in addition. 3/
Especially for those lucky enough to have landed one of the few remaining permanent positions, it’s important to change pace from a sprint to a marathon. That means that whatever does not fit into normal working hours has to be refused or dropped by the wayside. 4/
I start way more things than I finish; maybe 10% of every project I start eventually makes it to a paper stage. That’s not a good “efficiency”, but I consider it part of research. I learn from the dropped projects as much as from the published projects, no effort is wasted! 5/ https://t.co/w0EgNCjBbr
Another 20% of projects are finished (or contributed to) with minimal effort. There’s a nice story on how to decide what to spend a lot and what to spend a little effort on: not everything needs to be done to the same degree of perfection: https://t.co/337db3uXVZ
In addition, I’ve been trying to manage my workload by leveraging @Jira for my science projects and loosely-bound research groups, also for the master’s students that I’m guiding. This is a great help to reduce your workload into bite-size chunks. 7/ https://t.co/5GQcNpQwLR
@_SuSiSe_ The metrics are absolute rubbish as they miss most of what makes a good scientists. They do not quantify research quality, methodology, management, teaching and outreach, but solely look at output (money, publications) and popularity (citations, impact factors).
@_SuSiSe_ I have a “dark side of science”-presentation of about 1 hour that I regularly present on this topic. Unfortunately I don’t have a version yet that I’m happy to put on YouTube.
@_SuSiSe_ The last recording I was very happy with until I found out afterwards that my computer decided at the last minute to switch microphones to my crappy one. Crappy audio sucks.
@Jira All these are tools to try and handle a workload imposed by a broken system. I’ve been hired principally to do research, so why am I doing HR tasks, PR tasks, finance department tasks, funding searches, software tasks, engineering tasks, student support, administrative support?
@Jira Those are all tasks that my database-specialist partner mostly doesn’t have to bother with as they have functioning departments and teams. Here, they seem to have been administratively rendered so inefficient that it’s landed on our desks in addition to our normal work. 9/
Coupled with this is the #IchBinHanna problems of lack of prospects and growth opportunities for most postdocs. That leads to a brain drain in the field, and lack of permanence also means that we keep having to spend effort training people again and again. Very inefficient. 10/
I’m now (anecdotally) seeing a large number of people leaving science for industry, and while it is unfortunate, I think industry might offer a better alternative for many: 1) more pay, 2) better work-life balance, 3) better internal functioning, 4) a career plan
@jayveeMSE Oh I think there’s a lot of research that can happen in company labs. Gone are the days of large numbers of papers appearing from the large company’s physics laboratories, but I’ve worked with industrial partners who weren’t afraid to publish their findings! In the end, 1/2
Online workshop finished, lab work finished, and sprint meetings with the Master’s students finished, so time to go home and enjoy the weekend!
RT @RealSci_Nano: [admin] "Everything SAXS - Big Methods for Small Studies" Extended conversation with the amazing @drheaddamage is out n…
If you’re familiar with small-angle X-ray or Neutron scattering already, now’s the time to join our Data Analysis Round Robin! Deadline for submissions is end of March, and every submitter becomes a co-author. Plus you get to fit the cool datasets! https://t.co/XJbaiCmISV
Number 3 will surprise you! https://t.co/guaFBSarPU
Also give a follow to my amazing colleagues @ABuzanich who’s doing some X-ray spectroscopy on the @BAMResearch BAMLine, and @Helen_E_MC Who’s amazing with Neutrons in Australia
Also at the beginning of the pandemic, we had a good run hosting remote lectures with @drclairemurray @S9Glen, me and Jenni Haberland from @BAMResearch, under the name “The Light Stuff”. If you want to see more on scattering, there’s tons of videos: https://t.co/rxJxWLB06D
I’ll probably be posting a few more non-work-related things over the weekend, but for now, happy Friday afternoon! https://t.co/OH0TMeAu7U
Also if you want to contact us for collaborations on X-ray scattering, here’s the deal on that: https://t.co/RsW463HzcP
And lastly, if you want you can follow me on @drheaddamage, and feel free to ask me questions there too.
https://t.co/XvLAbptOFN
This acoustic levitation set-up seems to be cheap but reliable, and very compact. Wondering if it’s an option to replace the larger acoustic levitators sometimes used at beamlines with. cc. @evilokapi https://t.co/CNRlnIZNQT Would remove container walls -> lower background
@evilokapi @I22_DLS I’ve seen the complications from evaporation when using it for liquids. What about solids though, would this work for suspending powder samples?
@evilokapi @I22_DLS Was kind of hoping that loose powders might agglomerate into clumps in these fields..
Found a little gem on the street. https://t.co/8knfXTFgYG
Another wild wall.. https://t.co/ek4x0XMogw
I happen to reside in a pretty section of Berlin, and walking through it offers a nice glimpse into the older architecture styles of the early 1900s. What brings it down for me, though, is the eyesore created by the rows of parked cars. Seeing pictures of the same streets from 1/
… from the past, it is amazing what space there is available on these streets, plenty for trams (since demolished) to drive around and still offer oodles of space for pedestrians and cyclists. That space has all been taken now by private oversized cars. 2/
I understand the need for cars in areas with low population densities, and little in terms of public transport, but Berlin’s neither of those. Like Amsterdam in the 80s, this place needs a rethink of how people move around. This has become painfully obvious in the last two 3/
In the last two years with rapid acceleration of bike use, something that was already increasing steadily year over year. We’re getting to the point (that I call the carpocalypse), where something needs to give. Until then, neither side will be happy and stress levels rise.
It’s an interesting transition to experience, but also a very dangerous one. I see and experience aggression on the street on a weekly basis, I’ve been pushed off the road, shouted, honked and spat at, and overtaken with no space to spare more times than I can count.
There’s no doubt in my mind that an accident will happen sooner or later, which will result in scratches on someone’s car, and possibly hospitalization on my side, it’s a very uneven damage balance. Oh yes, I’ve also been deliberately run into, but at that point I was on skates.
I’ve received “lectures” from car drivers on that I need to show them “gegenseitige rücksichtname” when there was no space for them to overtake me. But I keep cycling, it’s free fitness for me, and a way to relax. In Japan, I did own a (nice RX-8) car which was fun…
But I also noticed there that if I would commute to work by car, I would get very unhappy and stressed. Once I discovered that, I could remedy it and go by bike which alleviated things dramatically. It’s not a solution for everyone, I know, but for me it works.
[admin] @Twitter @TwitterSupport can you help us with unsuspending this - @RealSci_Nano - account? https://t.co/YNmUPYaBxc
[admin] @svenja_lohmann do you see this tweet?
@MySci_PK @TwitterSupport I'm innocent! https://t.co/Ma2ArunCMh
@Swifthom Ah thanks, glad you liked it! And yes, you can always reach out to me. E-mails sometimes get "snowed under" in the constant barrage (or end up in spam), so do remind me if I haven't responded in a few days. Casual video chats are also possible to explore ideas.
Hey all, I've not been as active today as I had planned initially, turns out I'm a bit exhausted😅! I was planning a bike ride around Berlin to show some of the sights, but in the end I made a new household budget with my partner to figure out how to deal with the crazy inflation
There was a thing in the Netherlands salary scheme called "superannuation", which if I remember right, was a yearly salary increase to compensate for inflation. No such things seems to exist here. So every year we're a little worse off it seems (there's no career plan here)
We do have salary increases in the governmental "TVöD"-scheme, but the longer you stay in the scheme, the further apart they are - and the increases don't seem to cover the inflation we've had here for the last years. I often hear "but you like what you do, right?"
However, my partner also likes what they do, and they get regular salary increases. Those who earn enormous salaries also probably like their jobs, so the argument doesn't hold. (in fact, those with tiny salaries aren't necessarily ecstatic about theirs..).
Now I may just be another whiny millennial, but I suspect I'm not. I'm not an expert on wage disparity and inflation, though, so I'll leave this discussion there. However, if we want to encourage people to go into science, the least we can do is offer them a competitive salary.
I'd also like to say a few words about argumentation and argumentative fallacies, a topic I believe should be part of any decent high-school curriculum. This forms the basis of - and essential tools for - critical thought processes.
There are many ways in which we can be fooled - or how we can even fool ourselves. Some of these have been codified as argumentative fallacies. Learning about these has opened my eyes to them, I can recognize them in scientific papers too!
I learned about many of these by reading Madsen Pirie's "How to win every argument". I believe this is out of print, but if you search, you can find a PDF on google: https://t.co/T77DmaUOKe It's a seemingly bland book with alphabetical listing, but the examples are ace!
It inadvertently teaches you to recognize logical fallacies behind arguments, which you can then exploit to your advantage. But as mentioned, it also offers essential tools to recognize bullshit. Highly recommended! https://t.co/dTkDFDsHwO
@svenja_lohmann Age doesn’t matter, mine are about 15 years old and have had a fair few sets of new wheels over the years 😁. Now the kid is also regularly going out with their friends so I’ve successfully passed on the bug!
One last note about small angle scattering. I like building my own equipment but I’ve also seen many good X-ray scattering solutions offered by manufacturers. One thing bugs me though. The manufacturers are regularly doing the field a disservice… 1/2
1/2 they’re selling their equipment with the impression that any monkey could flip the switch and get good results. That gives the impression the technique is easy and doesn’t require a dedicated expert. However, like TEM, such equipment needs a specialist to 2/3
… to keep it up and running, and who can tell the users what they can (and moreover cannot) tell from the measurements. This misrepresentation has led to more than a few new instruments being left to collect dust not long after they were bought! 3/4
In the worst case, the instrument is used poorly or incompetently, leading researchers to get disillusioned by the technique itself. So please, manufacturers, give the technique the respect it deserves, admit it needs a specialist, and you might end up with happier customers!
RT @FDeGeuser: This thread reminds me of [insert any experimental technique here]!
Alright, that’s enough ranting from me! Hope you enjoyed my tweets, do give me a follow if you want to see more like this (@drheaddamage). Be well and stay safe out there! https://t.co/mt2RKNxgEK
RT @gudrun_lotze: Very wise words! Get an instrument scientist when investing in expensive equipment.
RT @svenja_lohmann: @RealSci_Nano I think the biggest problem here is that they successfully convinced lots of funders who now happily fund…
[admin] Thank you to @drheaddamage for a wonderful week of #science! 😊 You can find our #podcast episodes featuring Brian here ⬇️ https://t.co/OfbwLZdeU9 #MaterialsScience #SciencePodcast #ScienceTwitter #Nano #scicomm
Sakiru Abiodun
[admin] ✨"Surface Chemistry Reactions Make Nanomaterials Happy"✨ Please welcome @S_Abiodun01 for a wonderful week of science.🥳 Oh wait whats this 👇? Its a podcast ft. Sakiru. Listen in to know what is in store for this week!🎙️😉🎧 https://t.co/W4Kr0TYRjR
Hi everyone, I am Sakiru Abiodun. I am a 4th year Ph.D. Candidate @UofSC_Chem. I will be curating the Real Scientist Nano page this week. Today, I will be talking about myself and some of our work @GreytakChem lab. stay tuned🙂
Now, let's talk a little bit about myself...👇 I am a Nigerian, I had my bachelor's degree in Nigeria and started my Ph.D. in 2018. I enjoy talking about science and I am very passionate about promoting diversity. 1/n
I work on halide #perovskites quantum dots (QDs). My group: @greytak Lab work on the surface chemistry of colloidal semiconductor nanocrystals ( QDs). We also study charge and electron transport in the class of exciting materials. 2/n
During my free time, you can find me either listening to music, playing soccer, going on a long walk, or driving across the city/state, looking for African restaurants😀😀... I will be sharing some pictures from our lab soon, stay tuned🙂 3/n
One of the notable works we do in @GreytakChem lab is purifying QDs using the size exclusion based principle (GPC). Based on the diff in the size of impurities and that of the NCs, they can migrate through the column at different rates and we can achieve a highly purified QDs. https://t.co/bO3Qf04W2v
This is also some cool fluorescent QDs synthesis by our first-year student @moinulshdu https://t.co/rvOFC1HSUv
@jdhovland @GreytakChem LOL😃😃
This is our optical lab where we characterize electron/charge transport in QDs based devices. Yeah, we do play with lasers💪. https://t.co/Hb4NOppsLg
maybe a better picture? https://t.co/PVUB7LkWQE
This is our stage and the probe we use for our two-terminal device. https://t.co/YEqprobpF0
Now let’s play a game. If you were not in science or in academics, what other profession do you see yourself doing and why? Let’s see your answer in the comment section. I will go first... #AcademicTwitter #phdchat #PhD #phdvoice
I see myself being a journalist. This will still enable me to read, write and investigate things in my day-to-day activities.🙂
Taking about GPC purification, here is a paper from our lab where we showed that the properties of films made from QDs are sensitive to preparation conditions such as the purification method employed during the QD processing for optoelectronic app. https://t.co/AaXKfR1aCD
@Loberd3 wow, this is beautiful 🙂
Here is my paper that we pub. last year where we reported the use of gel permeation chromatography as a route for effective purification of CsPbBr3 perovskite quantum dots without being exposed to polar solvent https://t.co/BrTucPKFSv
Here is my other paper where we investigated the thermodynamics of quaternary ammonium ligand exchange (DDAB) on the surface of CsPbBr3 perovskite QDs using NMR and isothermal titration calorimetry. https://t.co/sqlRy5nWGw
RT @Loberd3: @RealSci_Nano Thanks. Few more of my favorites. All common animals where I live. https://t.co/6lJsWHJAW4
@Heidi_Colthup Lol😀😀 Maybe I need to re-think my choices
@NeuroEllen Yes, I think it’s a really cool profession 🙂
ACS San Diego was really awesome! https://t.co/FO8r6TqicO
Now, let’s do some recap on what we enjoyed most at the ACS San Diego meeting #ACSSpring2022. Feel free to add things you enjoyed about the ACS meeting and/or tag people you were glad you met at the comment section👇👇👇 #phdchat #AcademicTwitter
The first thing I enjoyed was the city view. Here is a picture of the city view from my hotel. It’s very beautiful 😊 https://t.co/TWp0EFL5fe
Here is another view during the day 🙂 https://t.co/hddjk7jmGB
Then the different water view that I love. 🙂🥰🥰 https://t.co/hlrDMEezdY
@ScienceByDRE This is good, we need more CEOs who can appreciate the fundamental science that are being done in the lab and in turn can transform/scale up the R&D into useable/commercial products.
One of the stand I visited at the #ACSSpring2022 was that of the @cenmag. It was amazing picking different newsletter for free 😁 https://t.co/hQtGomp8zE
Today I will be tweeting about different research papers in the field of nanoscience, particularly #halideperovskites nanocrystals. Tag the research group you enjoy reading their work as a PhD students! Let’s go 💪🏻🙂 #AcademicTwitter #PhDChat #PhDVoice
I love reading papers ranging from surface chemistry of NCs and ion migration in perovskites NCs from @mvkovalenko lab, @MannaLiberato @KamatlabND @BrutcheyGroup @brandicossairt and so many others…
RT @MySci_PK: Will our beloved @RealSci_Nano account reach 3000 followers by end of March? With the help of you all, I'm sure it can! Do s…
Help make the @RealSci_Nano reach 3000 followers. Just like Dr. Pranoti said, Do spread the word for good karma 😁 https://t.co/9yGuW7JHYV
Just published in @ChemMater 👇👇👇 Oxide Ion Conductivity, Proton Conductivity, and Phase Transitions in Perovskite-Derived Ba3–xSrxYGa2O7.5 0 ≤ x ≤ 3 Materials https://t.co/596HqMfux8
One of the cool studies of this paper is the nice STEM images. These were taken using Joel 2100f microscope @UofSC college of engineering &Computing. The microscope is also good for lattice-resolved imaging and sizing of small NCs https://t.co/PxwYg178Gr
This was a great talk last week given by Prof @jillianldempsey. If you are working on the surface chemistry of colloidal quantum dots, then you should watch the recording. Very detailed and comprehensive! https://t.co/nKmZAiCtEN
[admin] 🎧"Surface Chemistry Reactions Make Nanomaterials Happy"🎧 Extended conversation with the amazing Sakiru @S_Abiodun01 is out now.🥳 On spotify - Yes? YES!🤓 #UnderTheMicroscope #sciencetwitter #nanoscience #materialsscience #sciencepodcast https://t.co/c7ps0JxIIr
[admin] We are still on YouTube. If you like waveform while listening to the audio? Go ahead and click below👇 #UnderTheMicroscope #sciencetwitter #nanoscience #materialsscience #sciencepodcast #realscientists https://t.co/gMveJWRexQ
[admin] Oh we also have polls on Spotify and we are curious to hear your take! 😁 https://t.co/ZcZMgGNU8a https://t.co/nm28vLmTYU
Yo can now listen to my extended conversation with Dr. @MySci_PK on Spotify and YouTube where I talked about some of my research. https://t.co/lKLRVuqjES
One thing I mentioned during my interview is that the pandemic has changed my perspective on social media and has made me appreciate it more. Has the pandemic changed your views on social media? You can comment below 👇 and vote on Spotify. https://t.co/QLOaZs7yO6
A nice read for very PhD student working in the field of colloidal quantum dots (QDs)👇👇👇 Nanocrystal Quantum Dots: From Discovery to Modern Development https://t.co/ypuPACVKuP
“One beautiful aspect of colloidal QDs is the way their emission color changes with particle size making them perfect illustrations of the basics and wonders of nanoscience”- Andrey Rogach 👇👇👇 https://t.co/YdazAGvNSu
Quantum Dots and Their Applications: What Lies Ahead? https://t.co/KmJl3EQiWu
RT @MannaLiberato: Probably the best quantum chemistry book around, with its solutions manual. Very complete, clear in exposition, deep and…
RT @KamatlabND: From @ScienceMagazine "(If y0u) aren’t yet familiar with a standard rejection letter—or are just looking for some commisera…
RT @JamesMc51126628: Do any PhD students get days or weeks where they just can not face it? I love my PhD, the field and research is fascin…
RT @DeePraz10: Q: What is that one little change that you implemented in your daily life as a PhD, that changed or redirected your journey…
[admin] Thank you to @S_Abiodun01 for a wonderful week of #science! 😊 You can find our #podcast episodes featuring Sakiru here ⬇️ https://t.co/kiKElwkaGn #MaterialsScience #SciencePodcast #ScienceTwitter #Nano #scicomm
Jarrett Dillenburger
[admin] Tickling your tastebuds with "Lasagna á la Nano" Please welcome @jdillenburger for a wonderful week of science and listen to 👇🎧 podcast to know whats in store for this week! 🥳 https://t.co/8qSe9HTPTv
Happy Monday everyone! I'm Jarrett (@jdillenburger) and I will be this week's curator! I am an inorganic materials chemist working on my graduate studies @Penn @PennChemistry in the @MalloukLab
This week's podcast is titled "Lasagna á la Nano" I think Lasagna is a tasty way to highlight the unique structure of layered materials! Just like lasagna, layered materials are made up of stacks of repeating layers! https://t.co/366toz3Wwh
@SvenAskes Haha! It always makes me hungry when I'm working in the lab!
For a quick personal bio, I am currently a grad student in the @MalloukLab. I study layered materials --> transition metal dichalcogenides (TMD) and layered double hydroxides (LDH).
Before grad school, I attended @DenisonU in central Ohio where I received a B.S. in chemistry. Attending a PUI, I got great 1:1 mentorship from my professors who inspired me to go to grad school!
I started researching layered materials at @PSU with Tom Mallouk. I investigated layered sulfide perovskites with ferroelectric properties. We transitioned to @PennChemistry in 2019 and I started work on functionalizing TMD basal planes.
Recently I've been exploring layered double hydroxides to understand their water retention properties in bulk and as nanomaterials. I'm hoping to apply this work to making new types of alkaline fuel cells!
@goldclusters @MalloukLab I am so glad to hear that! What do you focus on?
@Andre_marinho91 Awesome! What kind of layered materials do you work with? TMDs?
I hope you’ve all decided to have lasagna tonight! 🍴 Inorganic layered materials encompass many different compositions and structural motifs Let me tell you about a few of the awesome variations out there: 💪 Threading🧵
Graphite and hexagonal boronitride (h-BN): These materials are made of one-atom-thick nanosheets. The individual 2D nanosheets are formed by covalent bonds forming repeating hexagonal structures. Meanwhile, the stack of sheets are held together only by weak Van der Waals forces https://t.co/jDiPFhwBNr
Transition Metal Dichalcogenides (TMDs): TMDs have nanosheets that are typically three atoms thick. The transition metal, (i.e.Molybdenum), is sandwiched between layers of dichalcogenides (i.e sulfur). Here again, only Van der Waals forces hold stacks of nanosheets together. https://t.co/2EJxhYk2ZG
Layered Double Hydroxides (LDH): 😍 LDHs are a class of anionic clays (i.e. hydrotalcite). The nanosheets have a positive charge and often anions like carbonate or chloride are found in between the layers along with water molecules. H-bonding makes them difficult to exfoliate. https://t.co/SLBF4zgTju
Intergrowth Structures: A broad class of materials that often includes layered metal oxides and perovskites structures. (also layered oxysulfides, sulfides, and oxyfluorides) Some of these materials can be exfoliated into nanosheets while others refuse to. https://t.co/BkGqNCz3Jc
Lasagna á la Nano: The most delicious type of layered material. Flexible sheets of pasta are separated by interlayer spaces filled with ricotta or béchamel, and bolognese sauces. Easy to mechanically exfoliate with a fork. 😂 https://t.co/j4aqf3u5aQ
Today I'm going to be talking about how I synthesize different inorganic layered materials. Not all methods need high temperatures, but this one does! #chemtwitter https://t.co/m0wXhJ3vND
When making bulk transition metal dichalcogenides (i.e. NbS2 or MoS2), I seal the elemental powders in an evacuated quartz ampule and heat them. It results in beautiful phase-pure crystals! https://t.co/0E5Vmi4K4O
I'm super curious about you all! Have you worked with layered materials? Chemically or otherwise? If you have, feel free to leave a comment about what you've worked on!
@CaboAntonija Awesome!
@Mchhattal That's fantastic! I'm certainly curious about MXenes tribology. I haven't heard much about it yet.
@johannaphys Fantastic heterostructures!
[admin] Extended conversation with the amazing @jdillenburger is out now, give it a listen on #spotify or wherever you get your podcasts! 🎧👇✨ #UnderTheMicroscope #sciencetwitter #materialsscience #nanoscience #nanotech https://t.co/w9SF66lN5Z
@drheaddamage Anionic or cationic?
@DTL So cool and so delicate!
I usually make nanosheets from bulk TMDs using liquid phase exfoliation. W/ the proper solvent, sonication can be used to shake apart the individual sheets. The results are lovely colored solutions of suspended sheets ^^ https://t.co/N2sfT1W3Uq
@drheaddamage Oh nice!
@Mchhattal Great question! I've explored methods for functionalizing the basal plane of these nanosheet materials. Basal planes are typically less reactive then the edges of the nanosheets due to the lack of dangling bonds. Basal planes have huge surface areas that are often underutilized.
@Mchhattal If we can functionalize the basal plane it opens the door to a whole host of potential applications in opto-electonics, catalysis, and sensing.
@Mchhattal I'd be happy to check them out! Feel free to link them here or DM :)
Here I restack an aqueous suspension of calcium niobate nanosheets using table salt! https://t.co/DmS2Tq0z7W
@LeNhanPham1 Ooo nice! I love seeing visuals like this! Good work!
Today in lab I am teaching an undergrad student how to prepare layered double hydroxides (LDH) using metal salts and urea. The urea hydrolyzes when heated, forming OH- which drives the formation of the LDH. https://t.co/ccRXBslXcB https://t.co/CbhcA7qSbb
RT @MicrotoPico: Really looking forward to next week: I will be curating the @RealSci_Nano account and tell you a bit more about my researc…
[admin] Huge thank you to the amazing @jdillenburger for a smashing week of science🥳 Listen to Jarrett speaking about his research and more on #UnderTheMicroscope podcast🎧 #materialsscience #sciencepodcast #nanoscience https://t.co/KibuJlTSEE
Kerstin Neuhaus
[admin] "Electrifying Science" Please welcome @MicrotoPico of @fzj_iek and @SchoolBaccara, @WWU_Muenster alumni for an electrifying week of science 😄 On #177 episode of #UnderTheMicroscope Kerstin tells us about what is in store for this week🎧 https://t.co/AueMQSdxxW
Good morning everybody. My name is Kerstin Neuhaus (@MicrotoPico) and I am super excited to curate the Twitter channel @RealSci_Nano this week. I'm looking forward to the interaction and many questions. Also, I am always open for collaborations – just get in contact.
I already have a lot planned for the next seven days. First of all, today I would like to introduce myself and tell you how I came to research with atomic force microscopy. https://t.co/N6R82HLd0L
I am already at the institute, but I will start with a little journey on how to become a #battery reseatcher, when you start out studying Earth Sciences...As a teenager, I participated in science competitions several times (@jugend_forscht) and couldn't decide
what excited me the most: chemistry or biology or geography? Therefore, I got the idea early on that geosciences could be the ideal study as it combines the complete field of STEM. I was particularly fascinated then, and still am, by space exploration and volcano research.
This is me on Tenerife in 2010, enjoying a hike at Teide volcano. https://t.co/rteSrCNvLS
If geology is something that excites you, too, please follow @Geology_History for a daily dose of Geology, and attend the annual Mineral Cup @MineralCup on Twitter for some fun information on various minerals.
So almost twenty years ago I enrolled in earth sciences at @WWU_Muenster and actually wrote my bachelor thesis in #planetology on the weathering of the meteorite El Hammami on different substrates (a chondrule of El Hammami still is my Twitter avatar). https://t.co/Lslj4ZLsE2
If you are interested in El Hammami, please also have a look at one of my old tweets. https://t.co/dRSFRcJdMO
In parallel, I worked in mineralogy and planetology as a student assistant and got a lot of experience working with SEM/EDX and preparing samples for TEM. I fell in love with microscopy ♥️🔬
While the work on #meteorites was incredibly exciting, I found it lacking in application. In addition, jobs in the field of #planetology are not that common. That's why, in addition to planetology, I focused on #mineralogy and #materialsscience in my master's degree and 1/8
also attended lectures on solid-state chemistry in the chemistry department. This turned out to be a great stroke of luck later on. But first of all, I wrote my master's thesis on microstructure development in piezoelectric PZT fibers 2/8
under different manufacturing conditions at @Fraunhofer_ISC in Würzburg/Germany for one year, which also included a lot of SEM research.3/8
I had been thinking for a long time that I wanted to continue working in research and applied to several PhD positions. In 2008 the master's degree was still relatively new in Germany; we previously had a 5-year diploma, which is a bit like integrated BS-MS. In addition, 4/8
many PIs apparently didn’t know anything about the subject of geosciences and were looking for a chemist for microscopy-based research, although analytics and, in particular, light microscopy and SEM are extremely important components of our studies. 5/8
After getting several rejections, I contacted the Prof. Wiemhöfer from the Chemistry Department of WWU with whom I had heard several lectures at the beginning of the master's and asked him 6/8
if he could maybe give me some advice on where I could possibly still apply for a PhD position.Only a short time later the answer came: "You don't need to apply elsewhere, I would like to have you as a PhD student" ...7/8
and thus my scientific career in the field of #AFM + #energy materials began. 8/8 https://t.co/xxnn3wHyG6
My dissertation topic was "Electrochemical Characterization of mixed ionic-electronic conductive ceramic membranes and the influence of carbon dioxide treatment" and revolved around oxygen permeation membranes, but I will go into more detail on this later. 1/7
So this is me right after getting my doctorate: we traditionally get a hat made by our colleagues and in addition, new doctors are pulled through the town on a decorated cart. 2/7 https://t.co/bt2ssIFdN5
During my PhD phase, in addition to my actual PhD topic, I was in charge of setting up a microscopy lab in our working group and assisting my colleagues with measurements on their materials (mainly ion-conducting polymers such as polysiloxanes and polyphosphazenes). 3/7
I ended up being scientifically responsible for three AFMs (two instruments from Keysight and a Cypher S from Asylum Research), a JEOL SEM, and a mineralogical light microscope, so I really had all the facilities to study my materials microscopically. 4/7
The good equipment is also the reason why I stayed in the same research group for seven more years after my PhD, first as a post-doc, then as an independent junior scientist with my own projects. Unlike many other colleagues, I only had very short research stays abroad. 5/7
A particular highlight was a trip to the Danish Technical University @DTUtweet, where I had the opportunity to work on the CAHT-SPM (Controlled Atmosphere High Temperature Scanning Probe Microscope, https://t.co/giN8ZSKJkE) at the research facility in #risø for some weeks. 6/7 https://t.co/O5Sljdzwwd
This instrument allows AFM-based measurements to be performed in various gas environments with variable pO2 and at temperatures up to 850 °C: Ideal conditions for the CeO2-based materials I was working on. 7/7 https://t.co/cLel0zrwZY
In April 2020, in the middle of the early days of the Corona pandemic, I moved from the university to the Helmholtz Institute Münster (HI MS) @fzj_iek, because I got the opportunity for a tenured position there,1/3
which on the one hand requires me to work in the administration of the institute, but on the other hand allows me to build up my own small research group. #NewPI 2/3
Since my husband is also a scientist and also holds a tenured position in the same city, we thus hit the academic couples jackpot. This also helps extremely with being parents in academia 3/3 https://t.co/D7uG3LKQeU
I've moved from the office to the home office and am currently rewarding myself with homemade rhubarb pie from yesterday and a big coffee. In a moment, I'll tell you a bit about #Münster as a Germany-wide hotspot for #battery research. https://t.co/ektexpsKdv
But before that, in preparation for my day tomorrow, I would like to know from you which microscopes you mainly work with.
In case you have nothing planned for this afternoon and would like to hear a talk on #batteries, the International School for Battery Chemistry @SchoolBaccara has a public lecture series, which takes place on Monday afternoons at 3:30 CEST. Please join at https://t.co/s1DcFnE24R https://t.co/qWdY3g2VfL
Now, I would like to say some words about the #Battery research in #Münster. Batteries are a very special topic here as Münster has rapidly become a hot spot for battery research in Germany in the last 15 years. In addition to the Department of Chemistry 1/3
and Pharmacy @WWU_Muenster and the #MEET Battery Research Center at the university, there are several scientific institutions and companies involved in research in this field. 2/3
This is the #MEET Battery Research Center in the background. In front is the site, where our new Helmholtz Institute will be. Hopefully, the institute building will be finalized 2023/2024, because currently we mainly share university premises and do not have our own labs. 3/3 https://t.co/sXcWlAjvf5
@svenja_lohmann Ok, that is special😃
In 2014, the Helmholtz Institute Münster (Institute for Energy and Climate Research 12 or HI MS) @fzj_iek (https://t.co/y4Y70jwHJS) where I have been working since 2020 was founded here as a branch of the Forschungszentrum Jülich @fz_juelich.
The institute is a collaboration of FZ Jülich, RWTH Aachen and WWU Münster. We deal with Ionics in Energy Storage, i.e. #electrolytes of all kinds. Research here ranges from solid electrolytes to polymer electrolytes, liquid electrolytes, and hybrid electrolytes.
This includes #material #synthesis as well as development or adaption of #measurement methods. All this is done in very close cooperation with the #MEET Battery Research Center (https://t.co/30RkkSMaRi), but of course we also have project partners from all over the world.
In addition to the university and the HI MS, the @Fraunhofer Research Institution for Battery Cell Production (https://t.co/sioyGyls6v) as part of the project FoFeBat (“Forschungsfertigung Batteriezelle”) was launched in Münster in 2019 as a cooperation of
14 Fraunhofer Institutes, RWTH Aachen University, WWU Münster with the MEET Battery Research Center, HI MS and the Center for Solar Energy and Hydrogen Research (Baden-Württemberg) as well as TU Braunschweig. The project is funded by the federal government and the state
of North Rhine-Westphalia with a total of about 680 million euros. The factory, which will be built at the outskirts of #Münster, will provide the infrastructure with which companies and research institutions can optimize the near-series production of new #batteries.
In addition, a facility for research on #battery #recycling will be founded in Ibbenbüren, which is a small town not far away from Münster.
Ok,now I am off to listen to the talk of Prof. Andreas Heuer at the public lecture series. See you later 😃
So, listened to another very nice talk 😃If you are generally interested in battery research, there are also several other great projects on this topic. For Germany/EU you can follow @2030Battery, @ClusterPolis, and @BIGMAP_EU and among others.
For battery research in general, there are e.g. accounts like @BatterySolid and @IntercalationSt who post news from this rapidly developing field. Also, if you speak German, I can really recommend the podcast of the research Cluster PoLis https://t.co/BxEazfM7ux.
Tomorrow I will be focusing a little bit more on lab work and have a look at different AFM-based measurement techniques.
Hey #AFM community. This could be something for you: next round of the @SchoolBaccara and @ECS_Muenster public lecture series will be by Prof. Florian Hausen on in-situ AFM measurements ⬇️⬇️ https://t.co/KQMs0n2aye
Good morning to all. Today I am staying in home office to finish analysis on some recent measurements on electrode materials we performed for a colleague from #MEET. So, from the poll yesterday (https://t.co/I893pyYwdq),
there are a lot of people reading this texts who are quite familiar with #AFM. Nevertheless, we will start with some basics 😃First, I'll take you on a tour through our lab. https://t.co/TOd4eTpewl
Admittedly, I'm very bad at filming, but you get an overview of our lab we are using at the Department of Inorganic and Analytical Chemistry. There are 3 AFMs (the big black box on the left also is an AFM), an SEM and a light microscope. We mainly work with the two AFMs I opened.
So, today is dedicated to writing a bit about atomic force microscopy (#AFM) and related techniques for electrochemical analysis and the possibilities in our lab. We were finally able to get our own AFM last October, and I am super happy that we now have all possibilities
to perform measurements at different temperatures between 0-120 °C and also in different gas environments and also in liquids. This is me in front of the new instrument, looking very relieved that the installation (finished on the previous day) went so well. https://t.co/4Qf5xVAamq
@Loberd3 I was really lucky to acquire so much money over the years to get my hands on 3 of them. The Keysights (black big box -> 5600 LS, small grey box -> 5500) were purchased during my doctoral studies at the Chemistry department and the Cypher ES is for my new group at @fzj_iek
@Loberd3 @fzj_iek But you are right: AFM experiments are extremely time consuming...
Most of you will already have an idea how an atomic force microscope works. Basically, a very small tip with a reflective backside is dragged along a sample surface. An AFM tip is really small. In the image, what you can see is the chip, on which the cantilever https://t.co/EqLtvsryEq
(the small antenna protruding from the pointy part of the chip) is mounted. At the end of the cantilever, pointing in the direction of the viewer, sits the AFM tip. It is only visible under the microscope.
This is how it look when we fix the cantilever into the tip holder of our Cypher ES. If you are tired, drank too much coffee, are excited, are clumsy, drank too few coffee… there are 1000 reasons, why mounting the #AFM tip can go wrong. https://t.co/yYgN25P18V
As they cost between 15-200 € depending on which tip you have, this is sometimes really annoying. After some years, however, you are properly trained to loose only a few tips per year… still makes me angry every time it happens. though. https://t.co/nJqkPRCl9h
The position of the tip on the sample can be determined with very high accuracy by pointing a laser on the reflective backside and measuring the reflection with a four-field detector. This can either be performed in constant contact with the surface https://t.co/YwyYK6J94x 1/3
or the tip can be oscillated at its resonance frequency (normally in the kHz range) if the surface is sensitive. This is called tapping mode, as the surface is only touched very gently. The resulting image gives information about the topography of a sample. 2/3
Here for example, is a Li4Ti5O12 (LTO) thin layer on silicon substrate: each pyramid is a spinel single crystal. Is a typical lithium ion conductive material used in the electrode of lithium ion #batteries. 3/3 https://t.co/9La3TIqBfx
We usually stick the samples onto simple metal plates with conductive C-tabs. They are then fixed in the specimen holder with a magnet. For electrochemical measurements we have sample holders with a cable attached to them 1/3 https://t.co/qzWO2HcyCR
or we contact the sample directly with Ag paste and a small Pt wire. The special thing about our approach is that we mostly do not work with samples specially made for the AFM, but get e.g. electrodes from post-mortem analysis directly from a normal cell. 2/3 https://t.co/7hFwcxyDym
These samples are often very rough and an analysis away from the topography is therefore often very difficult. 3/3
Apart from getting very nice topography images, we can AFM-based measurements to get information about physical characteristics of a sample. As the institute I am working at is dedicated to Ionics in Energy Storage, obviously we are very interested in 1/8
ion and electron conductivity of materials. Electron conductivity of materials can be measured very easily with the so called conductive AFM (CAFM) or current sensing AFM (CS-AFM) which both means the same: we take an AFM tip with conductive coating 2/8
(Au or Pt are common) and apply a voltage between the tip and a back contact which is attached to the sample (I mainly use conductive Ag paste to paint a contact). 3/8 https://t.co/wvOjbLMOz3
We can then measure exactly the current at each position where the AFM tip is and get corresponding information on topography and current flow. 4/8 https://t.co/hLDxnqMxF3
Here is an example: the topography and corresponding CS-AFM image of a cathode material with consists of a polymer binder and large graphite flakes. The applied tip bias was +2.5 V. 5/8 https://t.co/aTUueErYBg
As you can see, the flat areas on top of the flakes are not that conductive but the rims (very dark red, nearly looks black) have a high conductivity. This is to be expected as graphite is only conductive along the basal plains. 6/8
What you also can see: AFM images do not necessarily have to be in old-school brown images but can actually be in every color you like, which brings me to my next poll: 7/8 https://t.co/pYwiYTvoAC
What is your preferred color code for #AFM images? 8/8
So for me, I normally use brown or black and white for topography images and thermal for KPFM/CS-AFM images, so that the attention of the viewer is directly drawn to the colorful image.
Now we come to my method of choice: Kelvin Probe Force Microscopy or KPFM (sometimes also SKPM). With this method, we can use the AFM to measure the contact potential difference between a metal-coated AFM tip (I mainly use tips with Pt/Ir coating as some of our samples 1/5
have issues with Au) and the sample with high lateral resolution. In theory, as can be seen on the image, we can precisely measure the Fermi level of a given semiconductor. In a single phase material, this gives us direct information about variations of local defect 2/5
concentrations (e.g. variations of dopant cation concentrations, vacancies in the lattice or contaminants). There is a very nice, easily understandable paper by Zhang and Yates (https://t.co/Tljab3u7DN) about the situation at interfaces, if you would like to get more details. 3/
Also, there is another paper by Örnek et al. (https://t.co/MfBJUQRwbu) which explains very well the confusion between electrochemists and physicists, because in electrochemistry the KPFM signal is called surface potential while it is technically the Volta potential. 4/5
I’ll stick with surface potential though, because my colleagues are mainly electrochemists and speaking about Volta potential tends to confuse them even more than my explanations about AFM-based measurements already do. 5/5
But of course, measuring absolute value for the Femi energy level (or work function) of a sample with KPFM is not as easy as it sounds: for one, we cannot “see” the local chemical composition, so we have to use methods like XRD, XPS, EDX or EELS to get further information 1/5 https://t.co/ynSJAUw1Sa
about inhomogeneities. With polymers it becomes even more complicated as compared to semiconductors. Second, even small amounts of adsorbed species on the sample surface (like water from air moisture) can have a small effect on the signal. 2/5
Absolutely accurate measurements yielding absolute numbers can only be performed with super-clean samples in vacuum. 3/5 https://t.co/UXV84aVFVn
We cannot measure in vacuum, but as we are often working with Li metal samples from our colleagues, we have the possibility to either assemble the measurement cell in a glovebox (see image) or we even have one AFM which is attached to a mini-glovebox. 4/5 https://t.co/J4SHTFTnqE
The AFM cell can be completely closed and is then sealed, so we can keep the sample under Ar or we can also switch between different gas environments if necessary. 5/5 https://t.co/YYdIiOfPHs
@DrClaireDancer Thank you. I also started working on ceramic/polymer composites but I would choose pure ceramics for KPFM anytime 🥰
RT @DrClaireDancer: I'm really enjoying reading about Kerstin's work in her tweets on @realsci_nano this week - KPFM is such an interesting…
Sorry, forgot to attach the image... here you are. https://t.co/yVDdevorJD
@philjemmett @DrClaireDancer The pointy stick is even not changed that much (just sputtered with metal), there is "just" an additional feedback loop added in the instruments to nullify the contact potential between tip and sample. Tech is amazing 🥰.
@ZapotocznyBart @AFMCommunity @TrafficJournal Wow, very cool 👌
Finally, when we have performed all the measurements, we need to do the image analysis. This consumes normally even more time than the measurements, and you can make a lot of errors if you use all possibilities of making your image “look nice”. 1/5 https://t.co/SIH35s1ECT
For presentations, this can be done to some degree, but for evaluation of data, I generally look at the raw images and only make a minimum of changes (e.g. eliminating obviously faulty lines or adjusting the color scale). I am mainly using Gwyddion (free) or 2/5
MountainsSPIP (relatively expensive). I became used to working with Mountains because it was in a package with our Keysight AFMs. So I started using it in 2010 and now I do not want to miss it, because most of the possibilities getting information 3/5
out of the image data are really straight forward. But I am sure that there are more (perhaps also really good and/or free?) options, so here comes my second poll for today: 4/5
What software do you use for image analysis? If choosing option 2, please also leave a comment, which software from your manufacturer you are using and whether you are happy with it or not. 5/5
@johannaphys I am not really sure, but there is not such a big difference 😃But sure "orange" sounds a lot better than "mud brown", even if the difference in the images is small.
@apcarpenter1 I heard of it but so far never tried it myself. Do you know if there is a good tutorial?
Just to give you an impression, how rough many of the samples are, which we frequently get from colleagues in order to perform AFM: this is a specially conditioned anode material I am currently looking at. The surface is extremely inhomogeneous and rough. https://t.co/ZyWPsQvsZs
(Form was substracted, but no further image processing.)
This is a light microscopy image of the same sample surface. The small probe coming from the left side, which is slightly out of focus, is the cantilever. The tip is pointing towards the sample surface. https://t.co/95KLozKg0u
Before we start looking into the #materials side tomorrow: do you have any questions regarding #AFM-based measurements in our group? I am also always happy for good ideas and feedback…
@neutronic_nomad @ulrich_hofmann Correct, I thought the same. When you zoom in, you can also observe the tell-tale double features (this is really low resolution). Unfortunately, we have this problem very often because the samples are so rough.
@MohammedFaraj5 Yes, when there is an edge where the substrate is "visible" you can measure the height difference between the film and the substrate.
@MohammedFaraj5 Normally, if you measure directly at the edge you can measure the step height between the substrate and your film. I am not really sure what you mean with leveling?
@Mchhattal Well, I normally work with pretty rough samples which are not specially designed to measure AFM. If you want to achieve atomic resolution, that can really make a difference, but if you just aim for a broader view in the range of 1-2 µm more layers should not make to much dif.
Good morning. Today we will take a closer look at the materials I work with. In addition, today is also an exciting day for me because I will have a call with a colleague from Aachen and a colleague from Israel about a project we ware writing. But first coffee and e-mails☕️
BTW: Did you see that news yesterday? https://t.co/5oEsXK7D0X Space and AFM 🥰
Today I would like to talk a bit about #electrolytes and MIEC materials. So let’s directly dive into definitions. An electrolyte is a material that can transport charge not by using electrons but by transporting anions or cations. Typically, if you built a Daniell element 1/6
during school time or during a practical course at the uni, you probably have used aqueous solutions of some salts to receive a voltage from your system. https://t.co/jgn2sjaqit 2/6
The interesting point is, that charge transport by ions is not only possible in liquids. There is a plethora of solid electrolyte materials available, ranging from polymers with dissolved salts in them (e.g. PEO with LiTFSI as a typical Li+ conductor) or Nafion 3/6
(a proton conductive polymer) to Y-doped ZrO2 (high oxygen ion conductivity around 1000 °C, can be found as sensor material in the lambda probe in your car https://t.co/Ow4qpZGtEW). 4/6
You cannot build energy storage devices without cheap, mechanically and chemically stable and easy to fabricate electrolytes! They are absolutely necessary for getting away from #fossilfuels, 5/6
so recent events underline the importance of ongoing research in this field to improve #batteries etc. 6/6 https://t.co/uc1RvytP5x
BTW: There are also some fun possibilities to use "aqueous" #electrolytes... have a look at this video of the Royal Society of Chemistry @RoySocChem where they used 2,923 lemons to generate a voltage. https://t.co/Sf4Xw1EpVj So, if life gives you lemons, make a #battery 🍋🔋.
Apart from these pure ion conductors, we also find mixed conductors, which exhibit ion conductivity on the one hand, but also a non-negligible electron or hole conductivity on the other hand. These materials are MIECs or Mixed Ion-Electron Conductors. 1/
MIECs are extremely useful for energy storage applications. Of course, they cannot be used as a standard electrolyte material in batteries or fuel cells, as they would generate a short circuit between the anode and the cathode. But they can be used at the electrodes 2/
to include and exclude e.g. lithium ions during charging and discharging of the cell (e.g. Li4Ti5O12 or lithium titanate, which is a common material used at the anode of lithium ion batteries) or they can be used for proton or oxygen ion permeation in fuel cells 3/
(most prominent example would be the oxygen ion conductor Ba0.5Sr0.5Fe0.8Co0.2O3 or BSCF). In the image, you can see BSCF samples glued to the metallic #AFM sample holders with a dip of conductive paste at the edges. https://t.co/rb87y0xLdf
[admin] "Electrifying Science" Longer conversation with the wonderful Kerstin (@MicrotoPico ) of @fzj_iek is out now!🎧🥳 #materialsscience #nanoscience #AFM #WomenInSTEM #UnderTheMicroscope #sciencetwitter #sciencepodcast https://t.co/3UYR6DOgUY
For my dissertation and until today, I have mainly been dealing with oxygen ion conductors – a bit with BSCF, but most importantly (for me) with doped cerium dioxide. CeO2 is a very versatile material. It has cubic fluorite structure and can accommodate a lot of different 1/5
elements in comparably high concentrations as partial substitute for the Ce. Depending on the valency of these dopants, we can distinguish acceptor dopants (valency < 4), which increase oxygen ion and hole conductivity in the material, 2/5 https://t.co/53TpgTeQIa
and donor dopants (valency > 4) which promote electron conductivity. Acceptor doped ceria is cream-colored to brownish, while donor doped ceria is black and has a metallic shine. 3/5
In the image, you can see a set of ceria-ZnO mixtures from my Ph.D. Zinc serves as slight acceptor dopant, but has a relatively low solubility in the ceria matrix. 4/5 https://t.co/pn7rRj7qbs
BTW: have you ever seen the gorgeous colors the natural mineral fluorite (CaF2) has? And that it glows when illuminated with UV-light? Also, team #fluorite was in the semi-finals of last-years @MineralCup and you can find a lot of nice Scicomm and images of fluorites there ♥️ 5/5 https://t.co/HdT8P5szFX
So out of curiosity and as many researchers do not work with rare earth materials on a daily basis, I made a little quiz. Without looking it up, which of these elements is no rare earth element (REE)? Praseodymium, Dysprosium, Thulium.
BTW: this photo is already quite old. The respective publication on the influence of ZnO addition conductivity of CeO2 can be found here: https://t.co/cnUhGfDSjz https://t.co/Me0d0u68ZK
RT @MySci_PK: I love my @RealSci_Nano admin team for their quikryness 😂😂 https://t.co/RhQzKZ9lGI
Back to our MIEC CeO2… Our main goal was to tailor the electron and ion conductivity of CeO2 by using combinations of different dopants in order to maximize the oxygen permeation under certain conditions. For oxygen permeation, you need a gradient of the 1/4 https://t.co/LR4CGVKRII
oxygen partial pressure between both sides of a membrane made of acceptor doped CeO2, e.g. by having air on one side and Ar as sweep gas on the other side. Oxygen ions will then move through the material to equilibrate the conditions. 2/4
As the charge balance has to be kept, electrons have to move in the opposite direction. So, for really high permeation rates you need both good electron and good oxygen ion conductivity. This has already been achieved with BSCF, but his material is not chemically stable 3/4
against CO2, as the Ba and Sr on the A sites tend to form carbonates. Ceria, in contrast, is chemically really stable and uses much less transition metals (Co is the main issue here as it is toxic, often mined under dubious conditions and also is really expensive). 4/4
Typical applications for oxygen permeation membranes could be O2 generation for medical or scientific purposes where O2 has to be very clean or for the so-called oxyfuel process (that was the objective of my dissertation). Here, fuels are burned with pure oxygen to achieve 1/3
maximal heat output. Excess heat from the process could heat a membrane O2 generation plant, as typical solid oxygen permeation membranes need optimal temperatures between 700-1000 °C to work properly. By adjusting the burning process, gas burned with pure O2 would lead to 2/3
very pure CO2 exhaust, which could then be subjected to sequestration (carbon capture and storage, CCS). Apart from this, ceria can also be used as electrode material in solid oxide fuel cells. https://t.co/AUrFrFSHtw 3/3
With my change to the Helmholtz Institute Münster @fzj_iek, I also slightly broadened by focus: apart from oxygen ion conductors I now also deal with lithium ion and proton conductors. Most of my colleagues work with #electrolytes (mainly for lithium ion #batteries) and my group https://t.co/KfvC9eJyGX
is performing a lot of service measurements because it takes too much time to train a person in using the AFM and analyzing the images when they have something like four samples to investigate. This leads to a lot of different tasks, because measurement procedures have to be 2/4
adapted to materials with very different characteristics: solid ceramics behave differently compared to thin films which behave differently compared polymers or polymer-particle composites. 3/4
This is actually what I like most: every series of experiments has a different question and different challenges. I‘ll never get bored! 🥳4/4
Tomorrow, I will talk about what you can do with AFM and electrochemistry and I will go a bit into detail about a project on hybrid electrolytes for lithium batteries made from a polymer phase with lithium salt (to achieve ion conductivity) and additional ceramic particles. https://t.co/tHtTe1NH3f
Good morning. Today is "Girl’s Day" in Germany, which is a day of action held once a year to motivate girls and women to become #WomeninSTEM. There will be multiple activities at the university, e.g. the #MEET Battery Research Center has an online #battery event for girls. https://t.co/N8LweAWQm1
I will go a bit more into detail with some experiments we have been doing on different materials. https://t.co/B1Uduc6qGu
Hey, it's three hours left from yesterday's quiz... Even thought there was an error from me - the second button should of course say Dysprosium. Please vote. https://t.co/jphqRLVgbd
Today, I would first like to talk a bit about #AFM-based #electrochemistry. Electrochemistry deals with the connection between electrical and chemical processes in a material. For example, when we apply a voltage on an ion conductive material, we apply a force, which moves 1/6
the ions, which in this example are the charge carriers, in one direction. This can lead to local depletion or enrichment phenomena or it can trigger chemical reactions. This is the point, where AFM-based measurements come into play: “conventional” electrochemical 2/6 https://t.co/PgRpe5eo3r
experiments like impedance spectroscopy or cyclovoltammetry normally work with macroscopic electrodes. This means that the results you get when you gather information about processes in your sample generally represent 3/6 https://t.co/6QwdVhYB15
an average over the whole chunk of the sample which is covered by the electrodes. This is nice, if you would like to get information about your sample as a whole, but if you are after microscopic information e.g. about inhomogeneities or to inform some theoretical models, 4/6
this can be a problem. #AFM can help here: we have a very small measurement tip which can also be used as an electrode if it is e.g. coated with metal (standard AFMs come with an internal potentiostate). So, we can easily access tiny areas of the sample and 5/6
have a look on electrochemical characteristics without polarizing the whole sample. Using the AFM, we can for example apply voltages between tip and sample and measure the current flow (local cyclovoltammetry). 6/6 https://t.co/VbzSsLUVOW
@ulrich_hofmann Actually, I also just heard that there are possibilities for boys to look into jobs which are typically associated with females like working in kindergarden today. I think it's great both ways 😃
RT @SchoolBaccara: On occassion of #GirlsDay2022 in Germany we asked three of our PIs for useful tips and their inspiration to become #Wome…
As the AFM tip is so small, the majority of the voltage drop is directly near the tip (if we use a large back contact) and the majority of the sample are unaffected, yielding information about very small areas. 1/5 https://t.co/o3yRzDBxmk
We even have an electrochemical measurement cell to perform in situ measurements with a sample that is covered with liquid electrolyte: the sample is put on a brass counter electrode and covered with liquid electrolyte, the copper working electrode and the silver 2/5
pseudo-reference electrode (inserted through the small hole in the visible in the plexiglass of the lid) dip into the liquid. The AFM tip in this case is current free and can monitor e.g. changes in the surface morphology during charging and discharging of an 3/5 https://t.co/xEhcOoN00K
electrode material sample. In theory, this sound very nice. In reality, this often means a lot smaller signal-to-noise ratio compared to “conventional” electrochemical methods and also a higher standard deviation, as the results of 4/5
AFM are only for the very small part of the sample, while the “conventional” methods already yield an average results and normally are fairly comparable. 5/5
So, a lot of AFM-based electrochemistry is about finding the right sample preparation procedure, and making many, many measurements to get good statistics. One major problem is the sample surface itself. For ceramic samples, this normally is not a big obstacle, but polymer 1/
samples can be really tricky as they sometimes tend to be sticky, depending on the material. In some cases, the whole cantilever is covered immediately, so there is no possibility to do any measurements at all. https://t.co/xn511bjzsW
To all #AFM enthusiasts out there: how do you deal with sticky surfaces, especially with glue- or honey-like polymer layers which you want to measure? Freezing? Functionalized cantilevers? I would be happy for helpful comments! @AFMCommunity https://t.co/FNJISACMOz
Another point is measuring samples with very low (ionic or electronic) conductivity by using KPFM: the samples tend to accumulate static charge and the signal can be completely changed by this. 1/5
To the #AFM and #KPFM community: What are your tricks to prevent static charging of the samples during KPFM measurements? Please comment😃! @AFMCommunity 2/5 https://t.co/cOVOD9g0PJ
In our lab, there are some measures we can take, if the sample shows electrostatic charging: First, it is always a good idea to ground the sample (e.g. by attaching a wire with a little dot of silver paste and attaching this to instrument ground). 3/5
Second, it sometimes helps (for hard samples) to gently brush them with some aluminum foil. There even is an ion brush available for such issues, but I have never used one so far. Do you have experience with this? 4/5
A third possibility, which is only the last resort when measuring KPFM, is to increase the humidity in the sample chamber. H2O can then build a monolayer on the sample surface which is quite effective to get rid of surface charge, BUT it also influences the KPFM signal… 5/5 https://t.co/CDi5DoWG3m
As you perhaps may have heard in the podcast, there is actually one set of studies I am especially proud of 🥰. Already during my Ph.D. I started to develop and further adapt a method, where the diffusion coefficient of my oxygen ion conductive samples can be measured using 1/7
KPFM measurements combined with a polarization experiment. First, the initial state of the sample’s surface potential is measured using KPFM, second, a certain point on the sample surface is chosen and we apply a defined voltage between the tip and the sample for a certain 2/7
amount of time. Afterwards, we switch back to KPFM and measure the decay of the introduced potential gradient over time. As the oxygen ion conductors are really bad conductors at room temperature, the surface potential gradient relaxes very slowly 3/7 https://t.co/csaDBOgyLU
(sometimes taking several hours) so it can be easily mapped. Recently, we were able to show, that it is even possible to address single ceria grains in a composite made of ceria as oxygen ion conductor and a Fe-Co-spinel as electron conductor https://t.co/XHURQu4Kqo 4/7 https://t.co/fMzIXST4Pc
In the image, the ceria grains have a distinctly higher surface potential than the spinel and can thus easily be contacted.5/7 https://t.co/0yw30KNxxk
Compared to conventional electrochemistry or permeation experiments, this is a huge advantage. Another way of getting more information about single constituent would be polarizing the whole sample – something we will try for comparison in the near future. 6/7
We were very happy, that our research to apply this technique to #battery materials was awarded with a 3rd place in the poster competition for my PhD student Christina at the #AdvancedBatteryPower Conference this year. 7/7
BTW: we also used the results from this article for some Scicomm at the last #RSCPoster: https://t.co/tKBB32Pr4R https://t.co/qOF4Ox7kZJ
After talking so much oxygen ion conductors, I would like to show you an example where we used KPFM on lithium electrolytes: together with colleagues from @WWU_Muenster, we showed that we can use #KPFM measurements 1/3
to visualize the boundary between ceramic particles and ion conducting polymers in a hybrid lithium battery electrolyte (https://t.co/NP11XEy0Ef). This was my first independent paper as #NewPI and my first all-female authors paper… perfect for #GirlsDay2022 3/3
So why are these boundaries so important? 3/3 https://t.co/Ky4qVXmHMZ
Hybrid electrolytes are currently in focus of some large investigations, but it is not really clear, which role the particles have and if they really take part in the charge transport themselves. In polyethylene oxide (PEO), which was one of the polymer hosts we 1/8 https://t.co/VwvdsPYko8
investigated, it is assumed that particles mainly surpress partial crystallization of the PEO which improves conductivity. So it does not really matter, if the particles are able to transport Li ions themselves as long as they interact favorably with the polymer. 2/8
The other polymer matrix we investigated was MEEP (poly[bis-2-(2-methoxyethoxy)-ethoxyphosphazene]), which does not show crystalline domains. Particle addition (image below) does not have a significant effect on the Li conductivity of this material, so possibly the particles 3/8 https://t.co/B0BRp3nfWD
just do not take part in the transport processes. A possible reason could be a high resistance for Li ions to transfer from polymer to particle and/or back. Normally, this should lead to very restricted differences of the surface potential directly at the boundary between 4/8
particles and polymer. We were able to show that both in PEO and in MEEP, there are some small-scale variations of the surface potential visible, which depend on the type of particle (pure electrolyte, typical anode or cathode material) and on the concentration of the 5/8
conductive salt in the polymer. Why these exists and what they tell us about conduction processes is a topic we are still investigating. 6/8
This is a surface potential measurement with two small lithium iron phosphate (LFP) particles (small red areas) in PEO with additional LiTFSI. The particles are surrounded by a small area with decreased surface potential (blue). We were able to clearly identify the 7/8 https://t.co/Fw7uEsazgw
particles by comparing the phase images: the LFP is much harder than the polymer matrix and can easily be distinguished. 8/8
@Annelise_Elsen It's a electrolyte made of two different phases - normally a polymer and additional ceramic particles mixed into it.
I'll call it a day: tomorrow we'll talk about a topic that is very close to my heart - grain boundaries. In addition, we will see what little ZnO stars ⭐️ have to do with bacteria and funghi and how they look under the #AFM.
Good morning: today, I will work at the lab again. There are several meetings on the schedule and this afternoon is the ceremony where a former colleague will get her doctorate. But you will also hear of ZnO and stars, as promised. But first, coffee and kids to kindergarden. https://t.co/S6dbcvn7a3
Good morning everyone. Today I would to zoom in a little bit more on materials we discussed previously and talk again about boundaires, in this case about grain boundaries. So, what is a grain boundary (GB) and why are they so important? 1/6 https://t.co/Ihb7Ou8hSZ
Crystallographically speaking, a grain boundary in a single phase material is a very small area (1-2 nm width) in a crystalline material, where two areas - the grains - with different crystallographic orientation touch each other. There is a certain amount of lattice 2/6
mismatch and overall confusion in this zone, so it’s the preferred place for single phase materials to dump all the ions which do not perfectly match the lattice. Also, point defects such as voids or “vacancies” in the lattice normally occur in a higher concentration at GB. 3/6 https://t.co/zNMcSXHLvU
This increased concentration of so-called defects (e.g. vacancies, dopant ions, contaminations) severely change the characteristics of the charge transport at grain boundaries compared to the bulk of the material. In acceptor doped ceria, GB are mainly slowing down the oxygen 4/6
ion transport in perpendicular direction, while the electron conductivity along the GB is often enhanced, especially when transition metal oxides are added e.g. as sintering aids. 5/6
This also leads to a difference of the surface potential of the GB compared to the bulk, which can be measured with KPFM and related techniques. 6/6
In the past, I have worked with other research groups to investigate grain boundaries in a very exciting and versatile material: ZnO. This material normally is not so well known for its ionic conductivity (although there is some proton conductivity possible) but for
electronic applications. Historically, it has been used as a pigment, but nowadays you can also meet it in sunscreen or ointments for baby butts because it has an anti-inflammatory effect. https://t.co/AvYpVyzjKs
Regarding the electrochemical aspects of the GB: it has been shown that negative charges represented by missing zinc cations agglomerate directly at the grain boundary, while a positively charged space charge layer (SCL) surrounds the grain boundary. This SCL is produced
mainly by increased concentrations of oxygen vacancies and zinc on interstitial lattice sites but also impurity donor cations (D) at the place of zinc. D can either be donor dopants (H+ can also be a donor dopant in ZnO) or impurities like Bi or Sb. https://t.co/FiBbazBfqJ
In a collaboration with @JGonzalez_83, we were able to show by #KPFM measurements, that the potential barrier height at the grain boundaries of ZnO is strongly depending on the synthesis process. https://t.co/4CFXVl1V3g The work was focused on a new sintering method (spark 1/4
plasma sintering with addition of a small amount of water) that achieved dense, nanocrystalline ZnO pellets at only 250 °C. The densification was even better, when small amounts of zinc acetate were added to the water to manipulate the pH, and the group was wondering how to 2/4 https://t.co/h88Nglxju3
show what was going on at the GB. By using #KPFM and supported by impedance spectroscopy measurements focusing on the bulk and grain boundary conductivity, we were able to show that the treatment led to very high potential differences between grains and grain boundaries, 3/4
which means that there are a lot of defects around. For sintering, this is beneficial, as a high concentration of defects lowers the activation energy of the atomic diffusion. This is of course a simplified version, so for more details, please have a look at the paper😃🔬📚4/4
So far, I have been talking about ZnO pellets, but now we are coming to the promised #AFM measurements of ZnO stars: The Ceramics for Smart Systems group from the Instituto de Cerámica y Vidrio, CSIC in Spain was performing research on ZnO for antimicrobial applications. 1/8 https://t.co/e3NtiwOWfg
For this purpose, they already had synthesized star-shaped ⭐️ ZnO particles, which were working pretty well against the common germs Escherichia coli and Staphylococcus aureus as well as against growth of the fungus Aspergillus niger 🦠🍄. 2/8
Cathodoluminescence imaging showed that the tips of the stars had a slightly increased defect concentration compared to the bulk of the stars, but CL cannot see, whether these defect lead to a more positive or more negative potential at the tips. 3/8
So they asked me to perform KPFM on the particles. In #AFM, the stars look more like little clouds, as you can see in the topography image. 4/8 https://t.co/WrHXANaYb8
To date that was one of the most annoying samples as the particles kept sliding away as soon as they were touched by the AFM tip, but I was finally able to get some decent images of some. Side effect: I have greatly expanded my repertoire of swear words during this time. 5/8 https://t.co/VNUkUtXTJE
Finally, by combining our data, we were able to show that the star-shape of the particles which consist of stacked ZnO micro-platelets led to negative charge accumulations at the tips of the stars with an extremely high potential difference of up to 3.5 V between 6/8
bulk and tips. Apparently, 🦠 and 🍄do not like that. As the antimicrobial effect is due to physical characteristics of the particles and not due to chemical interaction, the major advantage is, that it will not wear off, so these kind of particles could be 7/8
ideally suited for antimicrobial coatings. For a more detailed analysis, please have a look at the paper https://t.co/OMXpFmc4D6 8/8
For my dissertation and also afterwards, the main material I worked with are CeO2 (ceria) based materials. Ceria has a fluorite structure. By doping with cations with lower valency than 4+, the material becomes also oxygen deficient. The free oxygen vacancies in the 1/3
lattice allow for oxygen ions to move through the material by a hopping mechanism. At grain boundaries, this happy hopping is much more difficult. Previous investigations found a much higher surface potential compared to the grain interior, that inhibits the propagation of 2/3 https://t.co/Zb7BtlR7nw
the oxygen vacancies, which have a net positive charge compared to the rest of the lattice. 3/3
Last year, I was able to show that we can use #KPFM to not only measure the height of the grain boundary potential barrier in ceria in dependence on grain boundary composition, but we can also us this method to determine the width of the potential anomaly. I used a
standard material for oxygen permeation (Gd-doped ceria) and added Al2O3 to get a model system. Al2O3 is an insulator and it has already been shown that increased concentrations of Al2O3 in combination with ceria (which is used for catalysis reactions where ceria is
the catalyst and Al2O3 is the substrate) increase the potential barrier at GB ➡️limited oxygen transport. KPFM measurements showed that the potential barrier at the grain boundaries not only becomes higher but also broader. This was confirmed with EIS https://t.co/sLTDgDaCF8
The grain boundaries can be easily distinguished from the grain interiors, as you can see here in the graphical abstract of the paper. https://t.co/qXwbm1uBIl
This can obviously be adapted for a lot of other materials, e.g. #battery #electrolytes where severe band bending or material segregation occurs at grain boundaries, which means that we get a strongly differing surface potential at the GB compared to the grain interior.
Hence, we used these findings for some Scicomm at the #RSCBatteriesPoster Twitter Conference last December: https://t.co/JiQb6JYmmK It was a great event with lots of exchange with other scientists, and we were even awarded the @nanoscale_rsc Nanoscale Advances poster prize 🏆😀.
@LunchBobs Thank you 😀
@Mchhattal No, I just regularly have a look at the phase signal, but normally I am strictly into electrochemistry.
RT @svenja_lohmann: Kerstin’s gif game over @RealSci_Nano this week is just spectacular 🤩
Since it's the weekend starting tomorrow, we're taking some time away from the daily grind in the lab for my last two days at @realsci_nano. Tomorrow I will talk about some mixed things and the day after tomorrow it's all about establishing @SchoolBaccara. Have a nice evening 😀
Good morning. Normally I try to avoid my desk at the weekends except for very urgent e-mails, but today and tomorrow, it will be a pleasure 😀
Today, I will talk a bit about some topics which are also important for a scientific career, but do not necessarily have to do with research: networking, #scicomm and being an #academicmom. #academicparents
new perspective… All this is easy if you have a network of fellow scientists who are supportive and like to engage with you. But building such a network is not so easy. The easiest way pre-Corona was engaging with people on conferences and workshops. I really used to like 2/6 https://t.co/m8zph1OXA7
the poster sessions on conferences to this end: everybody relaxed, got something to drink and just chatted about their research. If the discussion was interesting and I felt some sort of connection, it was easy to ask for contact details and to stay in touch afterwards. 3/6
During my Ph.D. and early post-doc years, I used to travel to 5-6 conferences per year (thanks to excellent travel funding by my projects as well as funding from the Wilhelm Klemm-Foundation @WWU_Muenster and from @DAAD_Germany). I really recommend that to all #PhDstudents 4/6
out there: participate in a lot of conferences, have a look at external funding possibilities. Often, the big conferences also have travel funds available for students. Plus, you have the chance to travel 5/6
That’s me on the 2011 edition of Solid State Ionics in Warsaw and the 2015 edition of SSI in Keystone, Colorado, enjoying the only free afternoon. 6/6 https://t.co/DjbzpO9SNw
Ok, 1st part missing: 1 of the things I recognized throughout the years is that networking is key to many things: getting new research ideas, finding collaborators to write proposals, getting test measurements to see whether your materials could also be investigated with a https://t.co/TTJ58Solpf
One conference especially stuck to my mind: it was a very small conference in a hotel resort in Sicily 🌋🥰 (Nonstoichiometric Compounds 2012). There were only about 80 participants, most of them well-known professors in their field. I think there were only about 1/5 https://t.co/Y0wWBguxrA
15 PhD students. As there was nothing around the resort, we really were together for breakfast to dinner for 5 days. I had so many interesting conversations and I really learned a lot. Another of these opportunities was a workshop at Roggenburg abbey in Bavaria in 2015, 2/5
where only 20 invited persons shared their research and discussed their findings on solid state electrochemistry. So, big conferences are good to get an overview, but small, dedicated conferences to my mind are the places where the connections are made. 3/5 https://t.co/j48giZKbH9
Now, with two little kids and online conferences, networking has become much more complicated. I really appreciate though, that many conference now are either online or in a hybrid format, because I would not like to leave my kids too often. 4/5
Still, networking online is not the same as grabbing a coffee and sitting down for a good chat in person (works especially well for me with additional cake 😉🍰🥰) 5/5 https://t.co/6fhmnHiRyQ
For this reason, we have now also set up a regular coffee round for the women of HI MS at the Münster site, where we meet (outside) for a coffee and muffins and exchange ideas – the HI MS Women Networking Café. So far, we have been meeting on a regular basis since March https://t.co/Nib20ddnyC
and I hope we can keep it that way. With all this discussions about #WomeninSTEM I feel it is really important as a woman to know the other female researchers surrounding you. This way, you can start lifting others with you when you are rising in academia. https://t.co/ZgqX5poOCk
The second point is outreach and #Scicomm: Working at the International Graduate School of Battery Chemistry @SchoolBaccara (more about it tomorrow) has given me a much better sense of the importance of communicating scientific results. 1/5
I only started tweeting about science at the end of 2020, but I really enjoyed it from the beginning. Due to the pandemic, networking on Twitter has at least begun to replace conferences in some places. In addition, there are formats such as #RSCPoster where conferences now 2/5
take place entirely on Twitter. Getting in touch with people there and talking about research has been very beneficial for me. Even though it's not entirely clear at the moment how Twitter will be shaped in the future, I'm confident that incorporating social media into 3/5
science communication will lead to greater participation of non-scientists in scientific knowledge. Also, I for my part am thinking about going more into direction of #Scicomm in the future and perhaps offer small video clips or more photo-threads on research of my group.4/5
So, curating this account was a great test, whether this works for me. So if you have got any kind of feedback on this week, I would be grateful. 5/5 https://t.co/N1tWZYdN4L
I'm sure you've already read between the lines that I'm not only a researcher but also an #AcademicMom. In 2016 and 2019, I had a break from lab work as we got our little daughters and I was on maternity leave for 12 weeks each time. For Germany, that is a really short leave 1/10 https://t.co/EncUzxzPup
(we are eligible to 12 months maternity leave with 60% of the previous years’ salary and in the first 12 months up 45 minutes of nursing time can be counted as work time when you don’t stay at home completely – a comparably comfortable situation), 2/10
but I always was happy to get back to the lab. #AcademicMom #WomeninSTEM My boss and also the whole working group were incredibly helpful during pregnancy and nursing time. I was able to make the microscopy lab “chemical free” apart from the ceramic samples I am using, so 3/10
I was able to stay in the lab for the whole time during both pregnancies. My colleagues have been awesome in supporting me: they helped when I needed something done in the other labs and when I turned up at the institute after lunch-time (my husband was working 4/10
in the mornings – me in the afternoon), there was always a fresh cup of coffee waiting for me in the social room. Also, important group meetings were scheduled so I was able to attend. In addition, the physics building where my lab was located actually even had a nursing 5/10
room (shout out to @WWU_Muenster), so these were already nearly perfect conditions compared to others https://t.co/E2gqFvPYyn. But it would not have been possible without my spouse. My husband and me both reduced our job to 50% to share care time, so he went through the same 6/10
problems as me child-wise and job-wise. We still share childcare equally and have both reduced our jobs to 75% permanently. This really was a big relief during the last two years, when we had to WFO and entertain the kids in parallel. Still, in academia this is not a 7/10
really common concept, especially not for men, but I think it should be more widely accepted. #AcademicDad #AcademicParents #MentalHealth 8/10
On occasion of the Girls in Science Day on Feb. 11th, me and a colleague from MEET Battery Research Center were interviewed on the topic of #WomeninSTEM: https://t.co/84rliToBvE. 9/10
Also if you are interested in more stories about this, I recommend following @Momademia and all those other great mums and dads in science. 10/10
Today is already the last day of my time here on this account! In the past few days I have already talked a lot about my research and personal views on some parts of my scientific career. However, since I started my position at @fzj_iek two years ago, I haven't done that 1/3
much research at all. In fact, I have spent a large part of the time on a secondment to @WWU_Muenster to set up the Graduate School for Battery Chemistry, Characterization, Analysis, Recycling and Application (BACCARA for short) @SchoolBaccara. 2/3
I would like to spend the last day talking about this exciting and refreshingly different task. 3/3 https://t.co/aNAQBjYP0W
BTW: @SchoolBaccara is hiring: there are 9 open PhD positions in the field of #battery #chemistry - everything covered from #synthesis over #analysis to #theory. Deadline is May, 31st. Please have a look at the link for details.⬇️⬇️ https://t.co/mXhvuQ2Wqt
At relatively short notice, the Department of Chemistry and Pharmacy and the MEET Battery Research Center at the WWU Münster @WWU_Muenster received the funding decision in July 2020 for a graduate school funded by @MKW_NRW. The school was going to be established to support 1/5
and educate45 young international talents in the field of battery chemistry. So someone had to be found quickly who was well acquainted with the administration at the university and the many different research areas in the department and #MEET, and at the same time could 2/5
handle the organization of such an extensive project. Unusually for a researcher, I spent both my doctoral and post-doctoral periods entirely in Münster, with the exception of shorter research stays. During this time, however, I was largely responsible for the third-party 3/5
funding of all projects in our research group. In addition, after twelve years at the same location, you naturally know a lot of people. Therefore, I was asked to supervise the graduate school project at least for the first months 4/5
and to build up an administration that could later take over the ongoing operation. 5/5
If you are interested in the different research topics of #BACCARAGradSchool, some of our PIs are also here on Twitter: @GloriusGroup, @GroeschelLab, @echem_nella, @ZeierLab, among others, and of course we have our own Twitter channel @SchoolBaccara.
So many things had to be organized quickly and in parallel: a recruitment process for PhD students with transparent evaluation criteria, hiring office staff, building a faculty of interested PIs who wanted to supervise PhD students, developing a curriculum of different https://t.co/enHGZazUsD
workshops and courses, and of course public relations to get qualified applicants and communicate the research at the graduate school to the outside world. It was an extremely challenging but also very educational time.
I don't think a PhD in STEM prepares you for a lot of these demands, so here's a little survey: were you prepared for or had courses in the following during your Ph.D.?
The first doctoral students should start work as early as winter 2020. Therefore, the development of an evaluation scheme for the applications was at the top of the to-do list. The challenge was that a total of over 20 working groups with extremely different research fields
(synthesis, method development, catalysis, electrochemistry, toxicology, theoretical chemistry) are involved in BACCARA, but we at the Graduate School have to make the candidate selection.
What values stand out for you when looking for new working group members?
We actually managed to get the first #BACCARAfellows to start working at BACCARA as early as November and December 2020. These now also had to be provided with additional courses. For the international PhD students, we offer German courses at the university's language center.
In addition, we have developed a concept for an introductory lecture in which various working group leaders talk about the basics of #electrochemistry and #battery research.
I also have a small contribution: one lecture about “Microscopy in Battery Research”, which gives basic introduction to #SEM, #TEM and #AFM
@MicrotoPico But obviously, hat is quite difficult to decide when you are hiring people for different teams. In #BACCARAGradSchool, we currently have more than 15 different working groups involved, but the hiring process is centralized.
In the meantime, we have put together a really great team in administration: an all-female team consisting of our two secretaries Laura Torricelli and Britta Weiguny and the two current Managing Directors Dr. Alexandra Kohlhöfer and Dr. Julia Quante @JuliettaQuante. 1/3 https://t.co/6S8o30qvUS
Since Alexandra and Julia have a background in humanities, the work in the management area is truly interdisciplinary and I have noticed again and again how profitable it is to look at things from a completely different point of view. 2/3
My secondment to #BACCARAGradSchool ended two months ago, but I am still a member of the recruitment committee and the directorate, so I continue to be involved in this exceptional project. 3/3
If you are interested in #Battery #Research, we are soon hosting an in-person conference in Münster which is mainly made for #PhDstudents: the #BACCARAPowerDay will take place on May, 19th and registration is still possible until May, 5th. https://t.co/o77w7CwkeN
There will be talks by experts from the field and participants can contribute posters. If you want to attend, write an e-mail stating your name and affiliation to conference.baccara@wwu.de. #battchat #batteries
In addition, @SchoolBaccara has a regular and free public lecture on "#Electrochemistry and #Energystorage", taking place on Mondays, which you are also invited to join. On May 9th, there will be an #AFM related talk by Prof. Florian Hausen. https://t.co/fQJ6qHTdZo
Side project for today: helping my daughter to design flamingo invitations for her birthday party.🦩 Eyes and beak will be added later with black pencil🥳 #handicraft #Momademia https://t.co/xnsxQmddyk
I took away three things from this excursion out of the research world. First: sometimes it is extremely beneficial for the development of one's own research personality to leave the comfort zone. I think I can use a lot of the things I learned at #BACCARAGradSchool to run my own
small research group. Second, I really enjoy public relations and communication via social media. I now often use my Twitter account, which was set up as part of the development of BACCARA, to network with other researchers and will probably extend that in the future.
Third, in order to work effectively, I need to take regular breaks #WorkLifeBalance. Indeed, over the past two years, solutions to problems have usually come to me not at work, but while cooking, playing with my kids, or exercising. #MentalHealth #AcademicParents
On that note, I'd like to give a follow recommendation to the @ChemistsWhoCook channel and #ChemistsWhoCook.
Have a great evening and thanks to the @RealSci_Nano team for the great opportunity to be host for one week. I really enjoyed it. If you would like to hear more about #AFM research from me in the future, please join me at @MicrotoPico.
[admin] Huge thank you to Kerstin @MicrotoPico for a smashing week of science. Do give her a follow! 🥳 Podcasts ft. Kerstin are on our website. Listen to the #UnderTheMicroscope on #spotify #anchor #googlepodcasts https://t.co/P5Icvld3PT https://t.co/gF1gtV84aG
Reza Rouzegar
[admin] "Ultra Fast & Furious Spin Dynamics" Please welcome @reza_rouzegar to learn more about his amazing research 🥳 What is in store for this week? Listen to the podcast to know 🎧😄 https://t.co/dUKFLKxTA7
[admin] For keeping up with all of our previous curators there's now an easy way! Subscribe to the Real Sci Nano curators list and get your daily dose of materials and nano science: https://t.co/TGGctqGEc4 https://t.co/VIR5hldInO
Hello All, I am Reza and I am a PhD student in THz Physics group in Free University of Berlin. I am so excited to curate the Science Talk channel this week. First I’ll introduce myself and talk about my carrier path.
I studied my B. Sc. In electrical Engineering in Shiraz. Shiraz is located in the south of Iran and has a population of approx. 1.5 million people. Shiraz is a really beautiful city which has so many famous gardens. I’ll share below few photos which I took few months ago https://t.co/2LKCVFuW76
Shiraz is famous for few things in Iran: 1) Shiraz wine 2) Poetry 3) Relaxed and chilled people As you can see all three are highly related :)) Famous poets are Hafez and Saadi.
Shiraz University is one of the top 5 university in Iran. It has more than 20K students and so many campuses around the city. I studied Electrical Engineering from 2010 to 2014 there. The photo shown below is the main campus of Shiraz University. https://t.co/FnGN1iJEqT
After finishing my bachelor, I moved to Milano, Italy. I studied Telecommunication Engineering in Politecnico di Milano. You can see the main campus of Politecnico do Milano in picture below https://t.co/LWH9imQB20
After Milano, I moved to Berlin and started my PhD in Physics. It was a quite big change and it was challenging at the beginning. I am now living in Berlin for 5 years and I’m at the end of my PhD and Hopefully will finish this year. Below You can see a picture from FU Berlin. https://t.co/tcwthjaRzm
I am also a member of International Max-Planck Research School (IMPRS) in Berlin. I am doing my PhD in THz Physics group with supervision of Prof. Tobias Kampfrath. Our lab is located at Fritz-Haber-Institut (FHI) and Free university of Berlin. Below you can see a FHI picture https://t.co/m0iDuhiShg
Today I’ll talk about metasurfaces. Below you can see an example of a metasurface I designed few years ago. Metasurfaces are artificial surfaces which are designed to achieve functionalities beyond the natural surfaces. Let me explain simply what is the metasurface below (1/6) https://t.co/Tl9mdIxzJL
Metallic surfaces reflect the electromagnetic wave in GHz frequencies fully but they apply a 180 degree phase shift (the reflection coefficient is r=-1). We can design an artificial surface which reflects the EM wave with 0 degree phase shift ( r=+1). (2/6)
These surfaces are called artificial magnetic conductors (AMC). Why do we need a surface which has r=+1 ? There are so many applications for such a surfaces, but one important one is to design high gain and more compact antennas, for example in your mobile phones. (3/6)
The prototype shown above is an artificial magnetic conductor working on f=11 GHz with 21% bandwidth. I worked on this project during my bachelor and my master studies ( 4/6) https://t.co/hSARMjgpSQ
You can check the paper below which is published in IEEE R. Rouzegar, A. Alighanbari and O. M. Ramahi, "Wideband Uniplanar Artificial Magnetic Conductors Based on Curved Coupled Microstrip Line Resonators," in IEEE Microwave and Wireless Components Letters, vol. 27, no. 4, 2017.
If you have questions about metasurfaces I would be happy to answer. (6/6)
[admin] Enjoying the week while @reza_rouzegar takes us into his science world? Listen to the extended conversation to dive deeper with Reza🎧👇🎧 #UnderTheMicroscope #sciencepodcast #materialsscience #nanoscience #scientistsontwitter #sciencetwitter https://t.co/1ZU2F2lQSs
[admin] 🚨News Alert🚨 It's time for another Curator update: Wanna find out what @CaboAntonija has been up to since curating here in October 2020? Find out here: https://t.co/5ZivMHMqQb You wanna listen to the episode ft. Antonija again? Find it here: https://t.co/oESA4Xvz7N
[admin] And if you wanna keep with all of our wonderful past curators, follow the Real Sci Nano curators list 😃 https://t.co/ZHNIrRqZlr
Recently I made an animation about about my research on “ Molecular Communication” during my master thesis. The animation explains in simple words the principles of #molecular #communication. https://t.co/5r6CkBIFKG
RT @zeliecomics: #PintOfScience global science festival has started! 🍺🧠 That's an occasion to show you the greeting card I illustrated las…
[admin] Thank you @reza_rouzegar for telling us about spin dynamics🥳 Missed tweets from last week? Listen to the podcasts to learn about Reza and his research👇 #UnderTheMicroscope #MaterialsScience #ScienceTwitter #Nanoscience https://t.co/ptROpp9Xdt
Lea Nienhaus
[admin] "Glowy Things & Why They Glow" Please welcome Lea @NienhausFSU of @floridastate 🥳 #MaterialsScience #UnderTheMicroscope #ScienceTwitter #WomenInSTEM #Nanoscience #womeninscience https://t.co/xSduvXE9xo
Good afternoon everyone! I am Lea Nienhaus, an assistant professor @floridastate and I'm super excited to take over @RealSci_Nano this week!
We will be taking you through scanning tunneling microscopy, #glowythings, #upconversion, #kitchenspectroscopy and more this week!
Starting off with some introductions: My beginnings in science were early, playing with a chemistry kit when I was about 6 years old... and dry ice to play with at birthday parties (clearly, the daughter of scientists!)
I received by https://t.co/1h1cI4KKle. from @uni_ulm. Ulm is famous for having the highest church steeple in the world (for now...) and being the birth city of Albert Einstein. https://t.co/yDWan0W2fg
I then moved on to the cornfields of central Illinois and obtained by PhD in Physical Chemistry working on Optical Scanning Tunneling Microscopy @ChemistryUIUC
Following my PhD, I moved to @ChemistryMIT to learn all about #glowythings and #upconversion in the Bawendi lab
Then in 2018 - the Nienhaus lab at @floridastate was established. 🎉🎊
Hi there! My name is Rachel Weiss and I have been working in the Nienhaus lab at FSU for almost a year now. I study semiconductor nanocrystals (NCs) and my research focuses on optimizing them for use as triplet sensitizers (more on that later this week).
My incredible high school chem teacher, Ms. Massi, encouraged me to consider a career in chemistry, after previously never considered myself good at math or science. I later got my B.S. in chemistry @JacksonvilleU with a math minor (who would’ve guessed!?) https://t.co/1JkPmD72m0
During an REU @SUChemistry in Dr. Zheng’s lab, I discovered my love of glowy things and research. I studied ligand exchanges in perovskite NCs and I even got to present my research at the NCUR REU conference! https://t.co/OCqIOiHEg5
since then - we've been having fun with #glowythings in lab and at home! https://t.co/LCZRIBABV1
These days I am happily working in the Nienhaus lab, where I get to make glowy things all the time! You can see what I am up to @Rachel591 😋 https://t.co/szbTWlyC2F
Today we will be tweeting about scanning tunneling microscopy! An 'atomically' sharp tip raster scans the surface and can map electron density on a sub-nanoscale size, enabling the visualization of single atoms 🤯 https://t.co/joGCHEWOKV
For this technique to work, a bias is applied between the tip and the sample - enabling quantum tunneling of electrons between the tip and the sample!
STM is so sensitive that even music playing nearby is picked up in the tunneling current/topography, enjoy our "acoustic STM" rendition of Queen's "Another Perovskite Bites the Dust" https://t.co/mtwf6N2zTb
Did you know that you can combine STM and optical absorption spectroscopy? Single Molecule Absorption STM: SMA-STM Adding laser illumination changes the populated electron levels in the sample - resulting in a change in the tunneling current. https://t.co/270zrZGYUQ
Using this technique, I've looked at 'atomic orbitals of PbS quantum dots during my PhD, and more recently we've applied this technique to #perovskites, stay tuned for more updates soon at @NienhausFSU... https://t.co/ywWhNADj9k
So... as if adding optical spectroscopy to STM isn't hard enough, why don't we throw some X-rays in the mix? Using XTIP at the 4-ID-E beamline at @argonne National Lab, we do X-ray absorption spectroscopy on the nanoscale, using the STM tip as a local probe. https://t.co/sYcPUAdcVV
with this, we've been able to track the palladium M2,3 edges when doped into perovskites: https://t.co/J8hwFRXy6E
In a different study, we've investigated the effect of bias polarity on the local environment of iodide in perovskites: https://t.co/jDkkuu7tc5
Spoiler alert: More coming soon....
[admin] "Glowy Things & Why They Glow" Deeper dive into @NienhausFSU is out now! 🥳🎧👇 #MaterialsScience #UnderTheMicroscope #ScienceTwitter #WomenInSTEM #Nanoscience #womeninscience @academicvoices https://t.co/o0zNIEqJqI
Today - what you've all been waiting for! We will talk about #glowythings. Today's topic is nanocrystals!!! https://t.co/AP2hq7HMHS
Now that we've seen atoms, let's talk about "artificial atoms", also known as quantum dots! Quantum dots bridge the gap between atoms and bulk materials, they have unique properties due to so-called quantum confinement effects. https://t.co/QtNChyzfcJ
Quantum confinement occurs when you force an electron-hole pair to be in a box that is smaller in size than its natural size, much like this reddit cat squishing into a box that's too small for it. https://t.co/FrKuWPzBkz
Therefore, different sized nanocrystals (quantum dots) absorb and emit different colors, as shown here for CdSe https://t.co/7xoyOipapv
How are these magical #glowythings made? We use the hot injection method where quantum dots nucleate and grow at high temperatures. Injection of precursors looks something like this for CdSe... https://t.co/o4V666DtUs
Sometimes you can even track the nanocrystal growth directly during synthesis. This is a hot injection process under UV light to see the beautiful glow. https://t.co/3R2goRuWRM
Sometimes we even invite theorists into the lab for some hands-on experience with #glowythings. This is our "interdepartmental outreach program" 😆 https://t.co/dqbGdwLAiV
It made our resident theorist @DePrinceFSU so happy! https://t.co/4ClPS55OfF
Perovskite nanoplatelets can also be made through a ligand assisted reprecipitation method at room temperature, watch them glow! https://t.co/0QyUuw4F8M
What is a nanoplatelet, you may ask? A nanocrystal that is quantum confined in only one direction, and results in a rectangular shape when we look at them under a transmission electron microscope. Image from @ZacharyVanOrman paper https://t.co/YsrjZUl6P5 https://t.co/SoU87zHQc4
@sciencenotscary I think you might mean sulfur.... ??? that stinks. Never smelled anything bad using Se...
@ZacharyVanOrman We can also make nanorods, where the excitons are quantum confined in two directions - sort of like a cat stuck in a tube. Scanning transmission electron microscopy image from @ZacharyVanOrman paper on CdTe nanorods, which we like to call "nanobananas" 😁 https://t.co/e2cCqi3k87 https://t.co/sy2KyAVaG8
Today we will be talking about bulk perovskites!
“Perovskite” is a general term for a crystal with an ABX3 structure. A is a monovalent cation, B is a divalent cation, and X is a monovalent anion. The composition can be customized, and you can even make mixed compositions, like the mixed halides we make in our lab. https://t.co/dLwDe84ePj
We make bulk perovskite thin films by spin coating precursor solutions onto glass and drop casting an antisolvent. The perovskite crystal structure is formed upon annealing, leading to a visible color change as the perovskite forms. https://t.co/j2NvU2JAyB
This is a mixed halide perovskite thin film in 405nm light. Perovskites are great at absorbing light, which is why they are used in photovoltaics. The blue emission is from the epoxy used to encapsulate the film, since perovskites are sensitive to oxygen and water. https://t.co/UkYoZCfPuY
Perovskites can be investigated by many different methods...
For example, atomic force microscopy can be used to determine surface morphology, as shown in our recent collaboration with @toniobuonassisi, @SunShijing and @SarahWi8 https://t.co/DMK7yegngT https://t.co/BOIdmzUm0d
PL mapping can show heterogeneities in the emission intensity and lifetime across the surface. https://t.co/sELuBfipEp https://t.co/L7zIPetBGc
You can also make single crystal perovskites, like this MAPbBr3 made by our undergraduate student, @Gregers00. How beautiful! https://t.co/LzlXUYsM8x
XRF mapping can also be used to determine the location of dopants in the perovskite. https://t.co/sELuBf0OfP https://t.co/ImrqrTsXkm
Of course, we also investigate perovskites with our old friend STM. STM can give insight into e.g., the effect of an electric field on the soft perovskite lattice. https://t.co/DSciVpV0sQ https://t.co/ztg7k2qlrQ
Why do we care about perovskites? They're fascinating materials, they glow, they make great solar cells, and they sensitize upconversion - stay tuned!
Today we will be talking about photon upconversion @Rachel591 https://t.co/G7ygKWr1Cl
Why do glowy things glow? If a photon (AKA a shiny crumb) is absorbed, an electron is promoted from its ground state to a higher excited state. When this excited electron relaxes back to the ground state, the energy can be released as light. This is called photoluminescence.
The excited states of our molecules come in two different flavors: singlets and triplets. In a singlet state (vanilla), the electron spins are opposite, while in the triplet state (rocky road) the electron spins are the same. This causes problems when you want things to glow…. https://t.co/D3cAYDSPoi
“Fluorescence” is photoluminescence from an excited singlet state. “Phosphorescence” is photoluminescence from an excited triplet state. But the optical transition into a triplet state is forbidden by selection rules ☹️.
Why do we care? We study photon upconversion, a process where low energy light is absorbed and high energy light is emitted. Do you believe in magic??? https://t.co/beWLBVDahe
Photoluminescence in general involves a loss of energy – higher energy light is input, lower energy light is output. In upconversion, higher energy is output. How does this not violate the fundamental laws of thermodynamics? When two become one…
Triplet-triplet annihilation (TTA) is our favorite mechanism of upconversion. Basically, two triplet states are smushed together into one higher energy singlet state, just like Kelvin and Fred smooshed into this cuddle puddle. No spin flips are required... https://t.co/RFvLSM2DYx
Since TTA requires excited triplet states, and triplet states aren’t readily formed by optical absorption, we use triplet sensitizers. The molecules that undergo TTA are often called “annihilators” or “emitters”.
More info on TTA in a recent perspective with @schmidtim, @drjessalves and @JialeF https://t.co/2aAxRXBo29
We use bulk perovskites and semiconductor nanocrystals as triplet sensitizers. These materials have two different triplet sensitization mechanisms.
Nanocrystals generally populate the triplet state of the annihilator by exciton transfer, while perovskites inject free charges to the triplet state. https://t.co/BzK81ge2gv
In this photo by @ZacharyVanOrman, inputting green (lower energy) light onto the sample leads to blue (higher energy) emission, AKA, upconversion! #FluorescenceFriday https://t.co/ahoJBrx9tM https://t.co/7Gp76Ea8dz https://t.co/aSLC63Ouik
In these photos by @NienhausFSU, infrared light is upconverted to visible light. #FluorescenceFriday For more on bulk perovskite sensitized upconversion, see https://t.co/opNQes1Dl0 https://t.co/YPXl1O725m
In addition to looking cool 😎, upconversion has many applications and allows us to learn about energy transfer processes, charge transfer processes, energy levels, fluorescence, etc… https://t.co/GudgAHSiG9
After a long day of research, members of the Nienhaus lab go home to their pets. Today we will have a tribute to the furry friends of our lab, @NienhausFSU.
In addition to being great models of singlet and triplet states, Fred and Kelvin have been known to help @NienhausFSU write grant proposals. #Caturday https://t.co/i8CNheOH94
Occasionally, they’re joined by visiting scholar, Knödel, the beloved cat of @SarahWi8. https://t.co/NcHFwzsRdS
Junebug enjoys relaxing with @CleverChemPun after long days working in the lab. Junebug also loves to play, but she has been known to prefer trash instead of cat toys. https://t.co/Qds6H14RWy
Waiting back home for her is the cat of visiting student @ElenaCambiotti, who famously joined her in studying for an inorganic chemistry exam. https://t.co/LrrN48t9sO
Onto the dogs of the lab! Starting with Frankie, who serves as an audience member for @Rachel591 during presentation practice. In her free time, Frankie works as an “analytical chemist” - detecting molecular amounts of food particles on the ground. https://t.co/QQlcdoW3Ve
While his dogs live a few hours away, @AlexanderBiebe6 credits Akira and Koda with helping him stay sane throughout the ups and downs of graduate school. https://t.co/rtTVl93xGq
Here we have Cooper, whose pictures serve as interim figures when @ZacharyVanOrman writes papers. Cooper's favorite glowy things include tennis balls and a glow in the dark collar. https://t.co/4cnXbXk0sf
Last but certainly not least is Ava, who @colettems_5 says is so cute that she makes you forget about any difficulties of day-to-day research. That's all for today, folks! Happy #Caturday (and dog day!) https://t.co/AdAD3TAAgi
Today, we will wrap up the week with some #kitchenspectroscopy! When the pandemic first hit, we couldn’t play with #glowythings anymore… at least that’s what we first thought.
But then, with a simple blacklight, we managed to have a bunch of fun in the kitchen! https://t.co/VZWfRKhtXq
With the help of @ZacharyVanOrman, I wrote one of my favorite papers on #glowythings at home! https://t.co/hN7HKW8lvd
There are so many #glowythings you can find around the house, can you recognize them all? https://t.co/jif8qTdbEA
Even my cat toys are glowy 🤷♀️ https://t.co/jQtO2RbJ9q
Who knew olive oil and capers were so glowy??? https://t.co/6Zh37NI1rk
Cheers! https://t.co/NNLfWceTpx
I highly recommend this glowy gin kit for any G&T lovers out there! #kitchenspectroscopy https://t.co/LWXfYDSgBR
Staying with the gin theme…More #kitchenspectroscopy can be done with purple gin, which is an awesome pH indicator (and tastes better than cabbage juice 🤢) https://t.co/D228po9OOD
Here’s an overview of just a few of the #glowythings you can find in your own kitchen!! #kitchenspectroscopy https://t.co/qEwGHr51un
Finally, in honor of my last day of curating this page, I baked a glowy bread 😁😁 Cannot wait to eat it! https://t.co/bIEqad5nq1
[admin] Huge thank you to @NienhausFSU and team, specially Rachel Weiss, for a wonderful week of glowy science! Podcasts featuring Lena are accessible here - https://t.co/SvvJxiMx1k #WomeninSTEM #UnderTheMicroscope #nanoscience #materialsscience #sciencepodcast #sciencetwitter https://t.co/vGboG2KViZ
Steph Gallant
[admin] "Nanodetectives Revolutionising Next Level Sensors" Please welcome @ChemGallant & listen to the podcast to know what is coming your way this week #UnderTheMicroscope #sciencepodcast #sensors #sciencetwitter #nanoscience #materialsscience https://t.co/yLoN8axPN5
Hi all! I’m taking over @RealSci_Nano this week, so I'll quickly introduce myself before getting into the science talk! My name is Dr. Stephanie Gallant, and I am a materials chemist currently working as a postdoc with the Masson Group at the University of Montreal ⚜️ (1/3)
I'm originally from Newfoundland, Canada 🐟🍁 and recently finished my PhD at Memorial University. I defended my dissertation at the end of January, and moved to Montreal for my new role just two weeks later 🤯 (2/2)
My current and previous work has involved using plasmonic nanomaterials to develop new light-based sensors ⚡️🔎 I can’t wait to tell you all about my career path, the cool research I’ve gotten to work on, and my hopes for the future of nanomaterial sensors! Stay tuned! (3/3)
Today, I'll start things off by telling you a bit about my early days! As a kid, I always had a grand curiosity about everything. I gained a reputation for asking a truly unbelievable number of questions 😅🤷🏻♀️ I simply needed to know the how and why for... everything! (1/6)
I have always loved learning new things and finding out whatever I could. Nothing was too mundane to observe, as exhibited by this qualitative study of human versus rabbit hair, from my beloved first furry pet 🐇 (2/6) https://t.co/cQZLJxAIki
By jr. high school, I was involved in science fairs, competing both regionally and nationally over several years. These were a wonderful experience into performing “real” science in a methodical way, as well as great practice in public speaking! (3/6)
Here is me around 14, taken at the national competition for Sanofi-Aventis Biotech Challenge (now Biogenius Canada), before giving a nerve-wracking presentation at the NRC in Ottawa! This also unknowingly prepared me so well for many elements of grad school! (4/6) https://t.co/OeELB1bhpA
From here, I went on to study chemistry and physics in high school, and then went on to complete a BSc in chemistry. After that, a PhD... which I did -not- originally plan to do! I was lucky to have the supports and means to carry through with all of this. (5/6)
The need to investigate and understand the world around us has always burned in me. Though many steps along the way helped lead me to the next, the passion for this career was always there😊 (6/6) https://t.co/V9bCNiPjrV
Now that you know a bit more about me, @ChemGallant, let's talk some science! I've been active in research since 2014, mid-BSc at Memorial University 🇨🇦 When meeting w/ the prof for my inorganic course (@merschrod), she offered me a research position for the term! (1/10)
Her group works in materials and surface science, studying both biological materials and novel sensing methods/materials. I ended up on the sensing side of things! This work involved developing + testing new sensors for Raman spectroscopy. (2/10)
We were working on enviro. sensors for monitoring polyaromatic hydrocarbons (PAHs) in water - highly-stable major by-products of oil & gas processes. Since detection at low concs (≤ μg/L) was of interest, we worked w/ surface-enhanced Raman spectroscopy (SERS)! (3/10) https://t.co/WEHJvXL120
Raman scattering is an inherently weak effect — only 1 in 1,000,000 photons will be inelastically scattered! SERS uses materials which boost the local electromagnetic field via oscillating surface electron clouds, allowing more photons-of-interest to be collected 😎 (4/10) https://t.co/LqzcLPKTzJ
These signal-boosters are known as plasmonic materials, where those oscillating e- clouds are referred to as a "plasmon" (a quasiparticle, depending on who you ask 😉) The classic examples of plasmonic materials are roughened silver or gold! 🪙🥈 (5/10) https://t.co/vDC6Fx9Wup
Whether presented as roughened surfaces or as individual particles, these plasmonic materials all have something in common: nanoscale features! The unique physical and optical properties of nanomaterials in general make them fantastic tools for spectroscopy. (6/10) https://t.co/AkS4z7DbjM
A quick example fr. my own work of how small nanoscale changes lead to differing properties: The pale pink slides here have an uneven gold film roughly 5 nm in thickness, while the dark purple-pink slide is after annealing the same slide at 300°C for a few hours. (7/10) https://t.co/hq0cT3tR4p
This image shows height mapping via atomic force microscopy (AFM) of these two gold surfaces, where we can see that the annealed sample is much more consistent (in height variation and pattern across its surface) compared to the freshly sputtered one. Wow! (8/10) https://t.co/YJxOjS8OxV
Nanoscale and plasmonic materials are clearly fascinating subjects, having so much potential for use in many fields. Most people have observed the beauty of the nanoscale without realizing it — a great example is stained glass, often made with metal NP colloids 😍✨ (9/10) https://t.co/QZsrSXCshy
I hope you have all enjoyed this little theory lesson and some background of my field 😊 Tomorrow we will take a look at my PhD research which touches on many of these things (+ more)! (10/10)
[admin] "Nanodetectives Revolutionising Next Level Sensors" Long podcast with the amazing @ChemGallant is out now!🥳👇🎧 #UnderTheMicroscope #sciencepodcast #sensors #sciencetwitter #nanoscience #materialsscience https://t.co/dgR8yQJNP6
I began grad school in 2016, and was lucky to have the opportunity to design my own project from the ground-up. I chose to study use of nanoscale magnetic metal oxides as the main sensing component of a SERS sensor. Was this an out-there idea? Maybe! Probably! (1/?)
Plenty of research exists looking at properties and uses of magnetic NPs; some work is specific to SERS/plasmonics, though most of the studies at the time only used the magnetism for easy handling/movement of NPs. (2/?) https://t.co/XNXK0jMq00
Such “core-shell” NPs are used for SERS where the outer layer of the NPs = classic plasmonic metal (Au, Ag), while the interior NP is made of another material, often magnetic iron oxides for quick manipulation through fluid/tissues/etc. (DOI: 10.1016/j.jmmm.2015.06.012) (3/?) https://t.co/cHLFqOBHQs
I noted that many of these studies around the time tended to ignore any contributions of the iron oxide nanoparticle (IONP) cores to the SERS activity, despite them often being in local range of the sensing surface! The IONPs: (4/?) https://t.co/GheLOLWVbA
Many researchers were then beginning to, and still are, looking into new classes/combos of plasmonic materials beyond Au or Ag, studying various metal oxide NPs, semiconductors, graphene/GO, carbon nanotubes, and more! (img DOI: 10.1063/5.0020752) (5/?) https://t.co/XNB43Qaq5U
It was this exploration of new, "unconventional" materials done by others for SERS which gave me some confidence to explore use of magnetic NPs as a major contributor to the SERS enhancement, and create a new design. A scary but exciting scientific chance! (6/?) https://t.co/iuaL5ZLjVD
There was a lot of learning and troubleshooting in this new project — I had never even made nanoparticles before this, nor worked in an inert environment — though some of that could just be said about grad school in general 🤔😂 (7/?)
But eventually, I made reliable magnetic IONPs! Here are some scanning electron microscope images of them 💪🏼🧲 (left: plain as-made NPs; right: organosilane-capped w/ APTES) (8/?) https://t.co/A0kKeQMWgz
Then the task was to design a "deconstructed" version of the Fe3O4@Au core-shell sensors, using the gold layer in a more background role, and the IONPs at the surface of the design... (9/)
It turns out the usual film-formation methods are challenging when your particles are magnetic, and you haven't forced colloidal stability and/or discouraged aggregation. Films were too thin at best, uneven and not reproducible at worst! (10/?) https://t.co/2h1hs8Tj0U
We tried switching our capping silane to a thiol-terminal one for better Au adhesion, but this caused some strange activity of the surface upon irradiation at 830 nm. We’re talking… fully saturated detector @ only 1% laser power🥴 along with changing peaks over time! (11/?)
New bonds/complexes forming seemed likely; w/ some digging, it turns out research existed showing the catalytic activity of MPTMS, particularly on NP surfaces, including reducing capabilities. In any case, we had to scrap that mystery + head back to the drawing board. (12/?)
When drying IONP films onto our Au coated substrates, space was limited in the glovebox, so I ended up placing some atop the hot plate inside. When I took the dried samples out, they amazingly looked uniform, which I realized was fr. the magnet of the plate! (13/?)
Though these films were also too thin, as glass fluorescence still dominated the Raman spectrum (a constant issue!). But the idea was sparked: could I just... use external mag fields to direct the NPs into ordered layers...?! (14/?) https://t.co/sZeXkyHJQa
Running with this, I tried several iterations, and long story short — it worked! What we ended up designing was a patterned multilayer of IONPs, forming a wheel-and-spoke type shape across the 2D surface, following the radial mag. field lines (atop a cylindrical stack) (15/?) https://t.co/dBxmU5xIVH
The many layers result in a rippling texture, with “hills” + “valleys” of NPs, where the base Au film can show through. Here is a depth profile of a region on one of the sensors! The sensing spot size for SERS at 20x would take up about a 20 x 20 μm area in the centre. (16/?) https://t.co/VhViqpiDKu
Testing our new nano/micro-featured surface, we determined a few important things for optimal function of the sensor: 1. Both the Au thin film + mag NPs needed to be present 2. The NPs had to be patterned 3. The laser had to be focused -within- the NP multilayer (17/?)
Here is our report including all the details for the research I've laid out so far! This covers our inital sensor design, testing/optimising this version, and trials for sensing PAHs in complex real-world samples (validated by GC-MS). https://t.co/zQ8lnqGw20 (18/?)
I had been continually interested in analogous forms of these magnetic iron oxides (Fe3O4/γ-Fe2O3) where the Fe2+ is swapped out for another transition metal — commonly Co2+ or Ni2+ — and the inverse spinel crystal structure is maintained. (DOI: 10.1002/sia.6568) (19/?) https://t.co/Q7BLPQxVKb
The type of magnetism does come down to e- counts and geometry, so that is a consideration when planning for a particular product! "Magnetic" = ferro- or ferrimagnetic = must have a net moment across the material. All considered, I chose to explore CoFe2O4! (20/?) https://t.co/ivDikMHijA
Our big manuscript is still in-progress on a lot of this cobalt ferrite sensor work, but I can share a few snippets! Largely, the tl;dr of it all is that scaling of nanoparticle syntheses are RARELY straightforward, but "bad" products aren't necessarily useless 😉🤔 (21/?)
Following a very similar synthesis to that of our IONPs, the products were -supposed- to be spherical little darlings... spoiler alert: not at ALL! We got mixed geometries as we scaled the reaction volume, but I decided to try making sensors with these products anyhow. (22/?) https://t.co/kFyNMcWSXM
All of the CFNPs had fairly different magnetic parameters than the IONPs — significantly larger coercivity and remanance values! This means these behave as permenant mini-magnets themselves, and ALSO respond to an external field. This vid shows how strong they are! (23/?) https://t.co/kZsfyr9fGz
Excitingly, the sensors patterned with these various CFNPs performed better than the previous version, boasting things like more sensitive signal detection at low concs and better reproducibility across replicate sensors. (24/?)
These sensors being better in function largely comes down to two factors: (1) The varied geometries + size scales of NPs (2) The large magnetic remanance + coercivity. (25/?)
(1) Geometry is super important for plasmonics, as we want lots of so-called "hot-spots" where we find the greatest density of electron clouds! Angular shapes can be better (cubes, octahedra), and lots of NPs touching help in coupling their individual e- clouds together. (26/?) https://t.co/6EM61UZBw2
(1, con't) We have angular morphologies [big octahedra], along w/ round shapes [very small spheres, medium disks], all patterned together on the surface. Lots of opportunities for coupling, especially w/ varied scales — eg. many spheres touching one big Oh crystal (27/?) https://t.co/riFh6g3sTG
@Orad Fumbling upwards on my own basically -does- describe the trajectory, and I stand by that 😤
@lukeweston Yes! People are doing similar things currently re: theranostics, and this has been on my mind especially since switching over to biosensing in my postdoc. Lots of potential there!
On point (2), as their properties allow the NPs to work as mini magnets individually, this means a magnetic field is being exerted (at least) locally on the surface w/o any additional influence. This backs up our original hypothesis that magnetism is impactful for SERS! (28/)
Optimal analyte sensing happens within the NP layers, so our laser is interacting w/ the particles/their fields + vice versa. While there may be some directional element of the fields to further explore, we are dealing with scattering of light in many directions anyhow! (29/?)
To further probe the magnetic properties potentially being the most important factor, we did a series of tests applying an external magnetic field to the CFNP sensing surface during spectral acquisition. (30/?)
While this did boost the signal across all sensors made with various products, the only statistically significant data (between the magnet vs. no magnet tests) was for the sample with the largest permanenet magnetism and biggest octahedral shapes ✅ (31/?) https://t.co/hrgDIBZ9Jr
The CFNP sensor experiments went above and beyond what I could have expected! As I mentioned, we are still tidying-up the final manuscript contaning all of this data, and working on answering a few final Q's before it's sent out. Tough to do this remotely for sure! (32/?)
There are many hopes I have for continuation of this work, but as I've moved on to a new role, it's uncertain if or how things will continue. There is so much potential for new variations, futher fleshing out the surface and enhancement model, etc.! (33/?)
But, aside from papers, we also have a patent for our novel sensors! This process started way back in 2018 with the first publication to the USPTO, and it has reached the final stages before (hopefully) being granted 🤞🏼 https://t.co/YXXYRt2UNp (34/?)
In my current role, I've switched gears a bit, getting into biosensing! It's a massive field with lots of very interesting, high-impact work, and where much of the groundbreaking SERS/plasmonics are developing. Especially revelant in the times we have been living through! (35/?) https://t.co/jHVNI0xdb8
Though the physics and chemistry theory is the same, I've had to learn a lot of biochemistry and biology! It's been a huge learning curve for such a physical chemist like myself, just to get basic acronyms and terminology down. Assay, CRP, IgG, PBS, ???? (36/?)
But! Luckily familiarity is setting in, and I've enjoyed getting to work in tandem with this "new" by working on things I'm more familiar with: Raman sensing, NP synthesis, and other various bits of chemistry. (37/?)
We are working on continuations of LSPR and SERS nanoprobe work done previously in the group, looking at various biomarkers in tissues and blood. These methods are particularly useful for biosensing as they are quick, affordable, and label-free! https://t.co/ipOk2rTkfo (38/?)
With this, that about covers the scope of my work thus-far in my early career! Thank you all for reading along this week — I hope you have found it both entertaining and informative 😊 You can always find me at @ChemGallant ✨ Take care!
[admin] Huge thank you to @ChemGallant for a wonderful week of science. Do give her a follow! Missed the tweets? Listen to the podcasts to catchup👇🎧🥳 #womeninstem #UnderTheMicroscope #sciencepodcast #materialsscience #nanoscience https://t.co/uRQDGx4nJq https://t.co/r6TYDymfjB
Alexandra Rosen (Brumberg)
[admin] ✨Raising the stakes - #nanoparticle playing cards✨ Please welcome @nanobrumberg Listen to episode 185 of #UnderTheMicroscope 👇to know what is coming your way this week! #WomenInSTEM #WomenInScience #MaterialsScience #Nanoscience https://t.co/iHAqoT5uuH
Hi everyone! My name is Alexandra Brumberg (@nanobrumberg) and I will be tweeting this week! I'm just waking up over here on the west coast of the US, but stay tuned today for an overview of my career path so far! #chemtwitter #phdlife #phdvoice #AcademicChatter
Recently, I've started attending a writing club every Monday, so it'll be a few hours before my posts start up. But, writing is so important to success in academia! I'm one of those weird people who actually loves to write... https://t.co/xul98DFbOs
Asking for a friend: How long can my diversity statement for #faculty job applications be? I have a lot to say on the topic...
First off, I wanted to share how I got started in science, because that's really where my journey begins! I did my undergraduate degree at @TuftsUniversity, where I majored in chemistry and math and got involved in undergraduate research almost right away. 🐘👩🔬
My research in Prof. Mary Jane Shultz's lab looked at the surface structure of ice, trying to understand which crystal face dominates when you grow solid ice from liquid water. This is actually a really hard question to answer, because all of the different crystalline faces...
...are really similar in surface energy! This is why snowflakes are all so unique ❄️ In the lab, I would grow single-crystal ice samples and then etch their surfaces to reveal the crystal structure below. Here, you can see the interface between two crystalline domains! https://t.co/WxGrVcSUNH
Next up: graduate school! I chose @NUChemistry because I loved how interdisciplinary the department was. You can really tell an NU alum by their work-- it's like everyone is doing materials/nano work! 🤩 Lake Michigan also might have sweetened the deal... https://t.co/kWtnvCyO8T
At NU, I joined the group of Prof. Richard Schaller, who works jointly between @NUChemistry and the Center for Nanoscale Materials @argonne. I was SO lucky to be able to call these two places my home-- the user staff at the CNM was so kind and was always willing to help me out.
The focus of my graduate research was the photophysics of CdSe nanoplatelets, which are nanoparticles shaped like playing cards: they are really thin in one dimension, but their lateral dimensions are (relatively) quite large. My thesis aimed to understand... https://t.co/aX3YojsjWJ
...how this dimensionality mismatch affected the dynamics and optoelectronic properties of these colloidal 2D nanoparticles, which are even more promising than conventional quantum dots for applications like LEDs and lasing.
On my way to group meeting this morning! All our meetings are at 9am, which is not my cup of tea... https://t.co/RvQ74lSFXH
Today, I've been in the lab! For my postdoc, I made a pretty big switch from my PhD, moving from ultrafast spectroscopy of semiconductor nanoparticles to self-assembly of polymer nanocomposites 😅 Right now, I am trying to understand how we can use external fields...
...like magnetic fields to control the hierarchical structure of nanocomposites. For example, by drying iron oxide/supramolecular nanocomposites in a 0.1 T magnetic field, we can produce composites that have the same nanostructure (positioning of nanoparticles, polymers, etc) https://t.co/nqNr4wequ5
...but that have completely different microstructures (larger scale order when you zoom out). This raises the question, can you make a whole suite of structures where the nanostructure is the same but the microstructure is varied? https://t.co/KDUNdUdfbM
Making such a big switch for my postdoc has been a massive challenge. But it has also really helped me refine my ideas and expand my knowledge. I definitely wish the community were more tolerant of exploration this "late" in a career!
For the most part, postdocs are valued for their expertise. Yet the whole point of pursuing a postdoc (from my perspective) is to gain additional training. This dichotomy is something I have really struggled with. On top of that, add in the pressure to publish in a short time.
@buerviper You could isolate the effect of microstructure on material properties. In a hierarchical material, each layer contributes to the overall properties. To understand how the microstructure plays a role, we need to be able to change the microstructure without changing anything else.
Today after work, I am watching @BronxZoo The Zoo (S4E14). I love learning about animals, so I'm often reading books about them or watching nature documentaries. (I would have made such a bad biologist though-- I hate being outside!!) https://t.co/GOvOJajyEd
[admin] ✨Raising the stakes - #nanoparticle playing cards✨ Longer conversation with the amazing @nanobrumberg is out now! Grab your headphones and listen 👇🎧 #WomenInSTEM #WomenInScience #MaterialsScience #Nanoscience https://t.co/AyPEPS6Rjw
Today I wanted to share about some of the outreach work I do, since it's such a large part of what I do "outside" of work. One of the organizations I'm most involved with is @LettersPreSci, a non-profit that matches middle school students with STEM professionals. https://t.co/iWpinEmglt
Throughout the year, pen-pals exchange 4 sets of letters, talking about school, college, science, and really life in general. Since each student is matched with a STEM pen-pal tailored to their interests (both science and general), the letters are super unique and individualized. https://t.co/jrAzFHpyVw
This concluded my FIFTH year as a pen-pal!! But actually, the program has been around since 2011. Next year, we're going to expand to 60 classrooms across the US, which will be our biggest program yet. You'll be able to sign up to be a pen-pal soon! https://t.co/f4zWYJc2b5
To accomplish all of this, we rely on grants from organizations like @ScienceSandbox and @AmgenFoundation, corporate sponsorships, and equally importantly, donations from individuals. It takes only $60 (or $5/mo!) to support a pen-pal's participation in the program for a year.
To donate: https://t.co/IqrQ2dIFnn ANYTHING HELPS!! Most of our donors support us at $5/mo!! To volunteer as a STEM pen-pal: https://t.co/PAHXi0MrGv To host @LettersPreSci in your classroom: https://t.co/cNbn6sErMb
Today is actually a very special day, because it marks 8 years that @Andrew_S_Rosen and I have been together! Here's a picture from shortly after we started dating, when he came to visit me in France (where I was studying abroad that semester) 😍🇫🇷 https://t.co/73hxRquSAH
What I'm reading this morning: https://t.co/Tb03WsgCpt "The desire to have children did not appear among... the most important factors in predicting whether [women] were interested in a faculty career." 🤯 Imagine that! /s
"Instead, faculty career interest was related to themes of overwork, high expectations from departments, and expected department emphasis on research despite an individual’s interest in teaching and mentoring."
"Furthermore, women expressed interest in maintaining work–life balance [and] a desire to work for a department that values mental health and diversity and supports its community members [but] low expectations for their ability to find a department that shares these values."
It may be hotter than I'd like today, but the view isn't so bad... @BerkeleyLab https://t.co/g04iDbtQif
@phyaaron Yes, I thought they did a really great job! There was definitely a recurring theme about how it's not what women want that's the issue, but rather that women feel their departments won't support them in what they need.
@Matter_CP Am I reading the job listing correctly that the job would be based either in Cambridge, MA or London (UK)?
I hope you're pumped for part two of this #TwitterTakeover, because I'm flying to Chicago today for my PhD hooding this weekend! It's time to *officially* become Dr. Brumberg! https://t.co/eftoVucOnz
Time for hooding! #TGSatNU #NU2021 https://t.co/jnrNaaGOk0
Ready for day 2! This time it's @Andrew_S_Rosen's turn to get hooded! https://t.co/jRd5JEvRQw
[admin] Thank you @@nanobrumberg for a wonderful week of science! Do give her a follow! ✨ Podcasts featuring Alexandra are available on our website👇🎧 #UnderTheMicroscope #WomenInSTEM #MaterialsScience #Nanoscience https://t.co/1agBM3oyKc
Susi Seibt
[admin] ✨Scaling Down a Chemistry Lab at the Aussie Science Donut✨ Please welcome the amazing @_SuSiSe_ 🥳 #UnderTheMicroscope #Nanoscience #MaterialsScience https://t.co/QvOki7cQld
*tap tap* Is this on? 🎤 Hello everyone 👋🙂 I’m Susi - a beamline scientist at the @ausynchrotron @ANSTO and I’ll be taking over this account for the week 🙃 We’ll cover a whole lot of cool stuff - hopefully some interesting bits for you all! 😉
But first things first, let’s start with a poll 🙋♀️🙋♂️ Does anyone know the Aussie Tron aka Science Donut?
@goldclusters Awesome! Sounds like you already got to work with some excellent colleagues of mine 😉
While the votes for the last tweet poll come in, I‘ll sense some interest in the ins and outs of our Melbourne Science Donut. 🍩 What do you say? Shall we have a look around? Follow me… https://t.co/qI1ns0NJH3
What is @ANSTO’s @ausynchrotron? It is a light source facility - in comparison to colliders (like CERN). We produce electrons with an electron gun and accelerate them to almost the speed of light (99.999987%) before forcing them with magnets on a circular motion. https://t.co/vXfNa6Pvzd
Those fast electrons don’t really like being forced on a ring by magnets🧲, so every time they are bent, they give of synchrotron light of all wavelength. 💫🌈 This light is extremely bright😎 and can be used by different instrument endstations, so called beamlines for research. https://t.co/ONCp7hBiCS
We currently have 10 operational beamlines - with another 8 being currently built as part of the BRIGHT program. 👩🔧👨🔧 But the synchrotron is more than just the science 🧬🦠🔬🩻 We celebrate the connection to Aboriginal knowledge and diversity of international staff and users. https://t.co/JhNoE214f7
The latest addition, thanks to the endless efforts of our Diversity and Inclusion committee, are rainbow steps. 🌈 Just in time for #PrideMonth, we got them installed in both the NCSS and main Synchrotron building 🤩 I love them and point them out to everyone I meet! #pride https://t.co/JSsqm8UkNP
Some random facts: - the storage ring (the outer ring where the electrons fly around in circles) has a circumference of 216m. - because we send electrons round and round in circles (it takes them 720 nanoseconds to go around the ring once) we call it the Science Donut 🍩 https://t.co/36K9fiWTLr
- we recently won the #SynchrotronMugMadness cup competition - proofing that we had the mug with the best pun (unfortunately the design is discontinued) ☕️ - we have free coffee around the place! ☕️ Secretly we say that this is actually the thing that keeps the place running 😉 https://t.co/evsLkmwuAu
- you can sometimes spot celebrities around the place 😉 when you come to visit - keep an eye out 🧐😁 https://t.co/i6LGqh2mSz
RT @_SuSiSe_: And while I’m busy showing all of @RealSci_Nano followers the shiny beamlines around the @ausynchrotron, my colleagues at MEX…
[admin] And if you prefer just to listen to what @_SuSiSe_ is planning for this week, here’s the podcast on @Spotify #Science #podcast #UnderTheMicroscope 🔬 https://t.co/8B3rYfIqvN
@EuropeanXFEL @ANSTO @ausynchrotron I know right? They look great!!!
Good morning everyone 🥱 In case anyone wondered why it was quite quiet after all on here yesterday (nobody wondered 🙄😅) - we had a public holiday. 🙂 But today, I have a full on program for you, introducing our shiny toys in a bit more detail. 🤩 But first ☝️ COFFEE ☕️☕️☕️ https://t.co/SJkXFGJGl9
Freshly fuelled with Melbourne’s finest coffee ☕️, let’s start our walk around our ring 💫/ donut 🍩 and look at the operational beamlines in a bit more detail - shall we? I’ll try and spread them out over the morning - each one as a separate thread 🧵, so you can keep up 😜 https://t.co/6Ncsqx7v1V
1️⃣ First up: Imaging and Medical Beamline Abbreviation: IMBL Fun fact: size matters - these guys have the world’s widest Xray beam 😉 Coolest gimmick: a monitor showing some examples of their 3D scans 🤩 1/5 🧵 https://t.co/S65005CuWt
This beamline is one of only a few of its type in the world! 🌏 Researchers use it for dynamic, high resolution, phase contrast 3D Xray imaging for tissues and bones for biomedical investigations 🤓 That’s quite a mouth full. But what does that mean? 2/5 https://t.co/37Zh4NHovo
The images you get from this beamline are similar to a medical Xray 🩻 BUT IMBL does that much faster and with higher precision. They can also scan in layers through an object and therefore create these lovely 3D images. And all of that in a non-destructive manner 👍🏼 3/5 https://t.co/HmKlwuc9o5
The team looks at all sorts of samples: shark heads 🦈, rhino skulls 🦏, full grown trees 🌳 and even living animals 🐑🐁. We have a vet and animal pen on site for that, to keep everyone safe and happy! The next step is to treat cancer in humans! 🤯 4/5 https://t.co/9b0itP1eiM
To get the world’s widest beam, they have a huge distance from the Xray source (🍩) to the detector - measuring in a satellite building 135m away, connected through a tunnel. The result is a beam width of about 45cm! This is also the reason we can’t run laps around the ring!🏃 https://t.co/tlF5550Ur9
2️⃣ next up: Xray Fluorescence Microscopy Abbreviation: XFM Fun fact: discovering hidden paintings is their speciality 🎨 Coolest gimmick: the most beautiful, coloured images of worms and plants 🌱 1/4 https://t.co/qR96XcCiqa
This beamline can map a range of elements at low concentrations but with very high resolution in a range of samples. Researchers use it for biological 🪴🪱, geological 🪨, cultural heritage ⛰ and industrial 🏭 samples. 2/4 https://t.co/NJyulW79Fq
They use the Xray beam from the source (🍩) to raster over a sample - which can be quite large - in micrometer precision to get quantitative elemental concentration maps. 🗺 This leads to these lovely colour 🎨 overlayed images showing where certain elements can be found. 3/4 https://t.co/qxL1DCO6rp
XFM can therefore reveal features from more than just the surface, demonstrated brilliantly in their collaborative project with the @NGVMelbourne where they revealed a hidden painting under Edgar Degas’ “Portrait of a Woman”. This made the news 🗞 📰 https://t.co/wJBla6UXny
3️⃣&4️⃣ Macromolecular & Micro-Crystallography Beamline(s) Abbreviation: MX1 & MX2 Fun fact: these are 2 different beamlines but I shall present them as a double up here. Coolest gimmick: @Elamanor’s artwork on their user cabin windows 🎨😍 1/5 https://t.co/maiFw1EIDC
Both these beamlines use Xray diffraction to determine the atomic structure of crystalline samples. 💎 The difference is that on one of them, samples are usually protein crystals, while on the other researchers are looking at chemical crystals. 🧬🧪 2/5 https://t.co/Bx08ks9Nqo
These beamlines are the workhorses 🐎 of the @ausynchrotron! Their super-fast and high throughput data collection means they can measure many 100s of samples per day - collecting a full data set of a crystal in as little as 18s!!! 3/5 https://t.co/aDuzfdRQUE
On top of that they have a sample mounting robot 🤖 for remote access, so researchers from all over Australia 🇦🇺 and the world 🌍 can send samples and run the beamlines from the comfort of their home. 🏡 4/5 https://t.co/lGdw2RguSJ
During the past pandemic years, MX was essential for a lot of COVID research 🦠, looking into the structure of nanobodies. One of the studies that made it into the news involved Alpacas 🦙 you can read it here: https://t.co/70kENXkmL6
RT @Elamanor: Susi is doing a beamline-by-beamline tour of the Science Donut! Follow to learn about the cool stuff we do here <3
RT @DrEmilyFinch: Follow along for a virtual tour of the scientific equipment @ausynchrotron!
RT @Elamanor: What can I say? You give me chalk markers, I'm gonna chalk-mark...
5️⃣ Infrared Microscopy Abbreviation: IRM Fun fact: they can run even without the source (🍩) with a separate light source Coolest gimmick: they don’t need lead shielding so they don’t need to search hutches to operate 🙌🏼 1/4 https://t.co/kfdQZOlSlf
This beamline combines the brilliance of the source (🍩) with a FTIR spectrometer and a microscope 🔬. This way researchers can analyse microscopic samples, like particles, thin layers or coatings. It accesses a wider range than lab IRs in combination with a microscope. 2/4 https://t.co/ttvsauDu5G
The molecular vibrations detectable with IRM are like signatures or fingerprints of molecules. 👍 Through a spatial mapping feature of the microscope, chemical maps of biological🕷, biomedical🦴 or food science🧀 as well as materials and forensics samples can be analysed. 3/4 https://t.co/iDC9taJmT8
The team works with researchers to look into the secrets of Australian basket-web spider’s silk 🕷🕸 to develop new biomimetic fibres for textiles, tissue engineering and medical applications. Spiders are definitely friends around here 😉 https://t.co/pRN8UzkUtc
Btw their neighbour beamline is our number 6️⃣ Terahertz / Far-Infrared Beamline Abbreviation: THz/Far-IR Due to a range of components and accessories available, researchers can do a variety of gas and condensed phase experiments here. https://t.co/oc2epTsRr9
7️⃣ inching closer to my workplace: Soft Xray Spectroscopy Abbreviation: SXR Fun fact: I call it the “airship” - like spaceship but reverse Coolest gimmick: their Toroidal Analyser on wheels that are controlled by a console controller 🎮 1/5 https://t.co/eS5RmsXEpQ
The SXR beamline is set up for Xray absorption spectroscopy of surfaces with low atomic number elements. 🆒 And with surface, they mean it as their Xrays only penetrate 10nm to a few Angstrom of the sample surface. 🤩 2/5 https://t.co/dXarUK0ruI
The wavelength of Xrays SXR uses is so high, that we call them “soft” and they are get completely absorbed by the first ~200nm of material. That’s why their endstation doesn’t need any shielding (no hutch). 3/5 https://t.co/vCiVGNttY5
That’s also why their endstations need to be under Ultra High Vacuum to be able to measure anything. The vacuum conditions are similar to that in outer space! 🚀 it’s basically an airship - an inverted spaceship 🛸 4/5 https://t.co/qkg3S0Wpqr
Their Toroidal Analyser for Angle Resolved Photoelectron Spectroscopy (ARPES) is the only instrument of its kind, as it was designed and built in Australia in collaboration with @latrobe. This enables excellent research into 2D materials like Graphene etc. 5/5 https://t.co/MWwEdDf7HA
8️⃣ welcome home: Small and Wide Angle Xray Scattering Abbreviation: SAXS / WAXS Fun fact: I work here 😂 - no “seriously”: we are known to constantly upgrade our beamline. When you come back, something has changed. Coolest gimmick: our wall of post-it thank you notes 🥰 1/6 https://t.co/d7tjsTVYF6
This beamline is probably one of the most versatile beamlines at the @ausynchrotron. 🙏 Due to our open sample mounting table, we can accomodate for all types of sample environments and experiments. 🧪🔬💉 And we can look at objects between 0.5 and 500nm. 2/6 https://t.co/M9OOanCf6i
The motto “everything goes” is sometimes taken quite literally: we can measure basically everything you can get Xrays through. Samples can be solids, liquids, powders, fibres, films, biological or synthetic, wet or dry, stationary or moving, hot or cold etc. 3/6 https://t.co/h03YrrHS2B
SAXS generally measures elastic scattering from Xrays, similar to diffraction. We talk in scattering angle, which follows a reciprocal rule to the dimension of the sample feature. Small or Wide Angle refers to the angular region of scattered beam to primary beam. 📐 4/6 https://t.co/AlK7PBLJMb
You might already know quite a bit about #SAXSland if you followed @drheaddamage in his week here. I do want to talk about some things specific to our beamline a little bit later 😉 5/6 https://t.co/e1aMnhJZ6t
One of the prime examples from our beamline in recent years is the “Malaria Milkshake” 🥛🦠 project we’re working on together with @group_boyd at @MonashUni. They / we recently won a @eurekaprizes for this research. You can read all about it here: https://t.co/qCFmenWFgi 6/6
RT @_SuSiSe_: Everything you always wanted to know about SAXS in one 🧵… or is it everything? 🤔😉
9️⃣ onto the finish line: Xray Absorption Spectroscopy Abbreviation: XAS Fun fact: XAS is a synchrotron-only technique! Can’t do that in the lab 🥼 Coolest gimmick: they currently have a High Energy Resolution Fluorescence Detection setup in one of the hutches 1/4 https://t.co/DpnzGgcK2e
XAS uses hard Xrays (so the opposite of SXR) to look at different oxidation states and chemical environments of specific elements in samples. They can also get information about the distance to and identify the neighbouring atoms of that element. 💁 2/4 https://t.co/KgJacmQdin
Samples can be liquid, solid or gas, but most often researchers opt for powders! Our XAS beamline can look at all elements between Titanium (Ti) and Plutonium (Pu), and at very low concentrations of them (100 ppm) 👌 3/4 https://t.co/2vLg1USxO9
During the pandemic, they worked with researchers from @excitonscience @UniMelb to analyse different batches of magnetic nanoparticles 🧲 for COVID test kits. 🦠 You can read about it here: https://t.co/NFHJULGs5b
🔟 last but not least: Powder Diffraction Abbreviation: PD Fun fact: they have one of the smallest datasets per measurement- only ~400KB Coolest gimmick: they can heat up and measure samples up to 1600 degrees 🔥 and cool them down to 10K 🥶 1/4 https://t.co/s3x6XSkzVm
This beamline can be used to look at crystal atomic structure both qualitatively (as a fingerprint) to see what phases are present and quantitatively, to see how much of each phase is present. 👍 2/4 https://t.co/GTaODjfqi5
PD is invaluable as a vast extension to lab XRD, as it can use different sample environments and has a large angle high resolution Mythen II detector, collecting data simultaneously over 80 degree. 📐 3/4 https://t.co/ktH79pgjqR
One of the largest community of this beamline use PD to look at batteries and their crystal structure during charge and discharge cycles. 🔋🪫🔌 But that’s not all. They do some excellent space 🛰 rock 🪨 research and indigenous projects too! ✋ https://t.co/27m9sZJ973
I think my dog Loki 🐶🐕 is telling me it’s time to call it a day wrt work! (It’s almost 5pm here in Melbourne) The perks of working from home some days 😜 Works great as timeline cleanser too 😊 Puppy eyes for reals 🥺 https://t.co/Ns51cZdmux
@LunchBobs It’s pretty great 😊 ngl
@M_LaddParada I hear it’s pretty convenient 😅 but I agree it feels weird they shoot “out in the open” 😁
@M_LaddParada Oh thank you! 🙏🏼
It’s a cold wet and windy morning in Melbourne, so we start the day at the beamline with an extra caffeine shot ☕️ I hope you are excited as throughout today we will take a deep dive into all things happening at #SAXSland @ANSTO https://t.co/2GbnwBdIH3
Busy day at work at the beamline 🤗 But what does this SAXS beamline actually do 🤨 and how does it work? 🧐 A thread 🧵👇 https://t.co/FUFJMtZmyo
SAXS is another form of light scattering - similar to blue skies 🏞 or red sunsets 🌅. While they are visible light from the sun ☀️ scattered by gas molecules or dust in the air and atmosphere, SAXS is scattering of Xrays, with a wavelength 1000times smaller than visible light. https://t.co/uC4AiLOyo9
We use it to analyse the internal structure of solids, liquids or surfaces. 🧊 And with structure I mean how the matter inside a sample is arranged over a wide range of sizes 📏 https://t.co/vS4mbJKtdt
So what happens when we put a sample at the beamline? 🤷🏼♀️ The incoming Xrays are scattered off the electrons from atoms of the sample ⚛️ How they are scattered depends on how the electrons are arranged spatially. They can have different density variations, distances or direction. https://t.co/5LOUYWkuoP
All of this influences the scattering pattern that comes out the other end. 💠 We use a sensitive 2D detector to collect these patterns. From that we can calculate the internal structure. ✳️ Unlike other instruments, for us samples don’t need to be optically transparent! 🔍 https://t.co/TBXRPqvhZ9
Let’s talk samples! 🧬🧫🧪 What can we actually measure - and how - at #SAXSland ?! Here is the thread 🧵 for all of you who are thinking of measuring SAXS 🧵👇 https://t.co/NXWFKV7sPy
The most common experiments and also the majority (so far 😉) are TRANSMISSION measurements. The principle is pretty straight forward: we measure through the sample ➡️➡️➡️🧪➡️➡️➡️ https://t.co/iPHbz0DttB
A small, highly parallel Xray beam hits the sample, some Xrays get absorbed but most travel straight through. These will be absorbed by a beamstop to protect our detector from being damaged. https://t.co/JZoKJCxIpa
Some Xrays that hit the sample are scattered in different angles as they pass through, forming a 2D, angle-dependent scattering pattern. ↗️ ↗️ ➡️➡️➡️🧪 These hold all the info about the structure and orientation of the measured sample. https://t.co/dKuv5FJnvV
Which angles are captured depends on the position of the detector relative to the sample. We can go as close as 600mm and as far as 7m - and everything in between. https://t.co/LnE6Ea2M49
The other measurement style is called GRAZING INCIDENCE. Here, we look at the surface of a sample by detecting the refracted beam. This is typically used to look at crystalline structures dependent on the incident angle of the beam. 📐 https://t.co/eFBgd7vZDX
For this method, we usually use a 6-axis motorised hexapod. This piece of equipment enables us to not only move in x-, y-, and z-direction but also precisely control pitch, yaw and roll angle of the samples. https://t.co/1XZdH0OmnB
Both of these types of measurement can be performed either in AIR or in VACUUM, depending on your sample! We have a super versatile sample table, several standard setups and a vacuum sample vessel, minimising background scattering to basically not existing! https://t.co/fpS2XGroJy
Oh and before I log off for tonight, I can’t forget to mention that we also do super fancy equipments. As I said, we’re a super versatile beamline and we give almost everything a go… https://t.co/sz3fO7NcL6
The latest addition is our shiny new @AntonPaar Rheometer. We got it through a collaboration with @SoftMatterHackr and are finalising the installation at our beamline. Soon we can do rheology and SAXS simultaneously 😵💫 https://t.co/VkvSpOVZ2X
My favourite, however, are microfluidic setups. Pushing the boundaries of fluid dynamics. 😍 I have been part of some pretty funky experiments in this field. But I will tell you a bit more about that tomorrow. https://t.co/XhkRNs6yk4
[admin] ✨Scaling Down a Chemistry Lab at the Aussie Science Donut✨ Longer conversation with the wonderful @_SuSiSe_ is out now. Check it out!🎧✨👇 #UnderTheMicroscope #Nanoscience #MaterialsScience #WomenInSTEM https://t.co/zhjr7qrEr6
RT @_SuSiSe_: Take a close-up look at our super shiny endstation. We love big vacuum steel vessels, so we got several of those, hiding even…
Too busy running users at the beamline yesterday (because Science 🤩) So we’ll use today to talk about Microfluidics instead 😉 I hope you’re as excited as I am! https://t.co/fcA790piDm
It’s-a me 🙋🏼♀️😉 Let’s jump into the warp pipe of Microfluidics - the Mario Bros. of Science 🧪🔧 (Although I got told I have more of a Princess Peach resemblance 🤔🤷🏼♀️) Anyways… here we go… https://t.co/EVLTo2Tn8q
What has Microfluidics to do with Mario Bros? People working with microfludics are basically tiny plumbers. 🪠 Microfluidics is a multidisciplinary field dealing with the behaviour of liquids 💦 in dimensions below 1mm. 📏 https://t.co/rhyqdLrtAx
So why warp pipe? Microfluidic systems typically transport, mix, separate or otherwise process and control fluids in small channels on devices. These can also include micropumps or microvalves. https://t.co/xpPOnPKv0Z
And why do we need this? Microfluidics is an extremely powerful tool to perform quantitative and qualitative analysis of a small amount of sample with high sensitivity and resolution. 🧪 They are also usually quite low cost devices, making testing and adjusting very easy! 🤑 https://t.co/GeH5CeYtcG
What can they be used for? Applications range across various fields, like analytics 💻, biology 🧬, chemistry 🧪, medicine 🩺 and technology 📱. “Standard” designs are trying to scale down chemistry labs to so-called lab-on-a-chip devices https://t.co/7UHlkJUoyd
But there is also a lot of development happening to produce efficient microarrays - so-called DNA chips 🧬- and even reproduce complete organs in microfluidics, called “organ-on-a-chip”🫀🫁🧠, which is a significant step away from animal testing! 🐭🐰 https://t.co/9C7oxT1VtA
RT @_SuSiSe_: Today I take you on a deep dive down the Mario Bros warp pipe of microfluidics!! Head over to @RealSci_Nano and read the in…
Now what did I use microfluidics for? I user 3D hydrodynamic focussing devices to look at super fast reaction kinetics during continuous flow. https://t.co/L7vPWkmOKE
Transferring reactions from batch to microfluidics is particularly useful to transfer a time axis (= fast reaction occuring) onto a distance axis (= measure along the channel of the microfluidic device) https://t.co/ELQJDPdwGw
When combining this now with a powerful technique like SAXS, we can follow the reaction at very fast timescales, like milliseconds, a measurement at a time = a step along the device at a time. https://t.co/UjltZ5t2FH
I used this to follow the nucleation and growth of nanoparticles, the shape evolution of nanorods from seeded growth and the assembly of anisotropic, pH sensitive particles. You can also couple this with different optical methods like fluorescence or absorption measurements. https://t.co/BkHgqh7dF1
RT @MySci_PK: TWO followers away from hitting 3k on our beloved account @RealSci_Nano Follow along and spread the word to make our week…
[admin] On popular demand we asked Susi if she can stay on the account for another week and @_SuSiSe_ said YES! 👇this is what is in store for you this week, listen listen🎧 #UnderTheMicroscope #SciencePodcast #WomenInScience #WomenInSTEM #nanoscience https://t.co/TpirqjyD3Y
Twitter friends - I did a cool thing over the weekend! 😎🤙 (Hence the silence 😴) On Saturday I successfully completed the Surf Coast Trail (Half) Marathon 🏃🏼♀️. Not only was this my first HM but on top of that also a trail run - including beach sections 🥵 https://t.co/BhCCUGDJHg
This event was at one of Victoria’s most iconic spots - the Great Ocean Road. 🌊 My happy place. 🧘🏼♀️🏄🏼♀️🏊🏼♀️ This prompted me to think about my decision to live in this corner of the world and the amazing science going on here. So I though I share some thoughts on this. 😉😊 https://t.co/k6zV8Bqzae
For everyone asking why I moved from the science and engineering hub Germany to Melbourne, I need to remind you that it one the title “Most Liveable City” several times in a row! 🤩 … and for good reason! First and foremost: the coffee ☕️ Melbourne is a coffee central! https://t.co/SMuV25CEQE
But as the 2nd largest city in Australia, it definitely claims the place as its science hub! 🧬🧪🧫 It has 8 public universities operating and covering all sorts of scientific research. Both @UniMelb and @MonashUni being part of the prestigious @GroupOfEight https://t.co/o06i6aU3lZ
It was the birthplace of the Royal Australian Chemical Institute @RACInational and the Commonwealth Scientific and Industrial Research Organisation @CSIRO, the backbone of Australia’s national lab system. 🥼💊 https://t.co/76boKNnTxb
The Victorian State government invested in Melbourne’s reputation as biotech hub by building institutes like @ausynchrotron (now part of @ANSTO) - our beloved science donut 🍩 , @Nanomelb - next door neighbour and Victorias @ANFFHQ branch, @Bio21Institute and @PeterMacCC 🧬🦠🧫🔬 https://t.co/HXb2gcFEaI
For everyone who wants to read more about the science hub Melbourne, feel free to read this lovely article from my former PhD supervisor @PaulM_ACEx in ACS Nano: https://t.co/oO7NtrAt4s
RT @_SuSiSe_: While being busy running (trotting? 🤔🤷🏼♀️) a trail half marathon down at the surf coast 🏃🏼♀️, I had time to reminisce about…
To finish today (I do have the Monday feels after the events from this weekend 🏃🏼♀️), let me hear what you think about Melbourne / Australia. One question coming up is about deadly animals… so tell me: Which animal do you think is the most dangerous down here? 🐙
And which one do YOU think is the cutest? 😍🧸
@CaboAntonija Very good choices! I guess Wallaby could be kind of seen as represented through roos in the poll? 🤔🤷🏼♀️ Kookaburras are definitely iconic! Maybe I should add a “native bird” poll 🐦🐤 I know where Magpies would end up on that…
RT @MySci_PK: @_SuSiSe_ @RealSci_Nano Here is @_SuSiSe_ telling me all about her trail run during our podcast recording 😅😅😅 https://t.co/SE…
@DrEmilyFinch The suspense of this nearly killed me 😱 I WANT TO SEE GHOST CAT !! 👻🐱
Bit of a trick question for you guys 😜 The deadliest animal in Australia is: 🥁 *drumroll* 🥁 The box jellyfish However, a good quarter had the right idea - on the list of deadliest animals globally, snakes 🐍 rank 3rd, right after Mosquitoes 🦟 and Humans 🙅 https://t.co/DH0TWsUAaz
And I definitely agree with Wombat as a winner - as well as with the complaints about missing Quokkas! I hear you!!! Let’s just agree that these little cuddly friends are definitely worth saving the climate for!! 🦘🐨🐻❄️ https://t.co/zPnET5Puva https://t.co/j5LvzRNmPC
Last week Tuesday I took you on a virtual tour around my workplace - @ANSTO’s @ausynchrotron aka science donut 🍩. Now that you hopefully decided that we’re awesome and chosen your favourite beamline (or the next best fitting for your research 😉), let’s talk access 🙋
Generally, you have to write and submit a proposal to get access to a beamline of your choice. 📝 Sounds daunting, but don’t worry - it’s not even close as bad as grant applications! https://t.co/eL1IfuU3jj
We have 3 ways of accessing beamtime: 1️⃣ Merit time 2️⃣ Commercial time 3️⃣ Mail in Now mail in samples are only run by MX and PD on a standard basis and commercial means a industry client / collaborator is paying for a service. But how does merit work? https://t.co/QfEQeuDCMo
Merit time is free for researchers. All you need to do is write a proposal stating why your experiment is awesome and why it needs a synchrotron to do it! There is a review process and upon success, you will be able to come down to Melbourne and carry our your science here. https://t.co/T3ELaiGgzz
We have 3 rounds per year and are trying to give as many groups access as possible. This is why we are constantly improving things to run better and faster 🧪💨💨💨 If you come from interstate you even get free travel and accommodation in our guesthouse! 🏡😴 https://t.co/YYLs6rvttM
If you’re thinking about applying for beamtime for the first time, I would highly recommend contacting the beamline team! We are an awesome and friendly bunch trying to help you! We can scope out possible experiments, help writing bits of the proposal and give you useful tipps! https://t.co/ERPo2YMUoj
Luis R. De Jesús
[admin] ✨To Transition or to take a Break....That's the Question✨ Please welcome @ldjesus_ and listen to the latest episode of #UnderTheMicroscope to know what is coming your way this week!🎧👇 #sciencetwitter #materialsscience #nanoscience https://t.co/bYs2leWjMI
Hiii, helloo, bueennaaaas!! My name is Dr. Luis R. De Jesús Báez (@ldjesus_ ) and I will be your emcee for the week. Big shoutout to the admin for giving me the chance to talk to you all. 👏 This week I will be talking about growing up in Puerto Rico; the desire… 1/2 https://t.co/NCA6jWiGDy
To grow up to be a scientist and a professor; my research endeavors; and my aspirations for the future. I can’t wait to share all that. Before we start, quick question, what do you consider to be your first experiment? #underthemicroscope🔬#RealSciencebyRealScientists 2/2
@svenja_lohmann That sounds lit!!! ✨✨ https://t.co/Hi5cwHM1LZ
Yesterday we asked, what would you consider to be your first experiment🥼🧪!! Let me tell you mine: first, we start with a fundamental question, does the light of the refrigerator stay on when you close the door? The curious child in me needed answers!! https://t.co/0Dl7UDRGzl
I did my experiments, I closed the door slowly to see if there was any change, and lo and behold, the answer: it turns off. My mother use to share that story all the time growing up. Thanks to the efforts of teachers and family members, that curiosity was always present.
Growing up in the island of Puerto Rico had its challenges when it came to find resources, but that didn't stop the zeal generated in me by my mother and father to find what I loved and follow it. https://t.co/vNBs9fnwvo
I ask you, who was your support group to get where you are? When did you find out that you were doing what you truly loved?
[admin] ✨To Transition or to take a Break....That's the Question✨ Longer conversation with the amazing @ldjesus_ is out now, give it a listen!👇🥳🎧 #materialsscience #nanoscience #sciencetwitter #sciencepodcast #podcast #spotify #anchor https://t.co/uZlHUJxRqH
Throughout my undergraduate career in chemistry, I had interesting encounters with a couple of professors who made it difficult to love science and chemistry. Even trying my hardest and showing up in my exam results, they would question my ability to be successful 1/5 https://t.co/ZW97ghannP
This is why it is important to have a strong support group that can be comprised of friends, family, colleagues/cohort, and other professors who can give you a hand during your processes. 2/5
With that said, the hardest times during my development as a professional were unrelated to the school itself, but life. My mom was a patient of cancer when I started undergraduate, that eventually metastasized during my start as a graduate student. 3/5 https://t.co/ObQEzbFPAE
I did not seek the right support during these times, and I worked as an unstoppable train during many of my days, to ease the pain. I needed to take a break and it wasn't until the start of the pandemic that I realized how much I needed to just take a breath. 4/5
Tomorrow I will be talking about all my sciences, but I want to remind you, it is ok to take a break. It is ok to transition. It is ok for you to feel. Science needs more scientist that learn how to think logically and feel humanly. You are one after all 5/5 #Youcandoit https://t.co/8cNES2AzZ4
Today is my last day to share with you more of me and I appreciate all of the responses and interactions for the past couple of days. I have shared growing up experiences, experiences with professors as an undergrad, and ideas about what is to be a scientist (in my perspective)
Now, this is #UnderTheMicroscope🔬 and I need to share what is my passion in research. If you get a chance to listen to the short podcast, you will hear that I care about what happens to solids, better known as materials, locally when it goes through a phase transition
When we think of phase transitions we sometimes think of of the state of matter, and while this is true, what we are truly seeing is a change in entropy in relation to the enthalpy of the system. We are seeing a system going from ordered to disordered and vice versa. https://t.co/rZpX0IAAHV
This happens within solids. It can have one phase (ordered structure X) and go into another phase (ordered structure Y) depending on the stimuli. Imagine the gif to be a solid that undergoes a stimuli (pressure, temperature, electrical, etc.) and it will change to adapt to it. https://t.co/f5SPsVgcI6
As a grad student, I employed a super microscope that uses X-rays at the @CanLightSource to scan what happens locally to an electrode material when exposed to Li-ions, more specifically, how does concentration affect bond changes and its correlation to the phases that exist
This was published in @NatureComms (https://t.co/661CmQlUjX). One thing we learned is that the diffusion of Li-ions within an electrode is related to the formation of polarons (electron and crystal movement correlated). An electron "cheating" while playing musical chairs https://t.co/IyPc3P6XfB
This was also part of my postdoc work, where we were exploring environmentally friendly etching mechanisms for MXenes.
As an assistant professor, I know care about phase transitions in materials under strain/stress and on solids that are already highly entropic (high entropy alloys). Wish me luck. jajajajaja
[admin] Huge thank you to @ldjesus_ for a wonderful week of science, do give him a follow!🥳 Missed tweets from past week? We got you covered, watch this video ft. Luis talking about his research, science journey and more! https://t.co/rmZN0FlKSQ https://t.co/vF2Eej9N0U
Jessica Henty-Ridilla
[admin] "Everyday is a Bones Day" Please welcome @cytoskeletown (Jessica) for a wonderful week of science!🥳 Check out the latest episode of #UnderTheMicroscope to know what is coming your way this week and a super fun conversation with Jessica!🤗 https://t.co/r5806MVdOs
Hello and welcome! This week I will be taking over the @RealSci_Nano account and tweeting about the cellular "bones" that my lab studies in the context of ALS. "Everyday is a bones day" when you study the cytoskeleton!! Check out the podcast here: https://t.co/jRkxhmEQ51 https://t.co/pWattguIUg
In my laboratory @InnovateUpstate we study proteins and cells and how both can go wrong in neurodegenerative diseases like amyotrophic lateral sclerosis (ALS). https://t.co/ZV4thq341P
Our research on actin, microtubules, and ALS takes a whole team to get done... so before we get into the details of all that, here are the people that make the cool science happen! https://t.co/lq4OV7HTiO
I HOPE YOU ARE READY FOR MY FAVORITE PROTEINS TOMORROW!!!!!!!!!!!!!! https://t.co/538R6sOyrQ
My lab studies actin and microtubules. Today we are going to get to some open questions with regard to ALS. First I am going to tell you a little bit about these dynamic proteins, so that you can love them as much as I do. Welcome to "Cellular Legos 101" https://t.co/bjnEPe92MB
@MySci_PK we had a slow start this morning!! lol.
Mutations in over 50 genes are causative in ALS. 8 are direct regulators of the cytoskeleton including: Peripherin, Neurofilament, spastin, a tubulin isotype, dynactin subunit-1, kinesin5a, alsin, and profilin.
We are using biochemistry and cell biology to study mutations in profilin, which regulates both actin and microtubule assembly!
Surprisingly, we have have a bit of a handle on what happens to the microtubule cytosksleton in ALS. Long story short, if you mess up the tracks or detach the motors that shuttle protein cargos around the cell... its not so great for your neurons and they die.
some of the profilin mutations disrupt microtubule dynamics by no longer binding to the sides of MTs (M114T, E117G, and G118V). While almost all mutations (8 total) disrupt direct interactions between profilin and actin monomers https://t.co/WCSsKtWVX4
next we want to learn more about how ALS-profilin misregulation of actin and microtubules contributes to disease! how we will do that... comes tomorrow!
NO CELLS HERE! We also use microscopes to perform "classic" biochemistry on a coverslip! there are only purified proteins (actin is visible, profilins are not). But we learned that ALS profilins had different affinities for actin subunits than WT. movie credit: liu et al. 2022 https://t.co/EnG1Whxhfc
I am nearing the end... but what questions do we have now? what would be interesting to study "next"? its time for "intriguing open questions"
1) what is the role for the cytoskeleton in ALS? Mostly it seems to be about "tracks for transport" but could this go beyond track development, maintenance, or more specifically extend to disruptions in "dynamics"?
2) profilin interacts and regulates both actin and microtubules. what is going wrong in ALS? disruptions to individual cytoskeletons? both? with other regulators like formins?
For example, profilin also interacts with other ALS causative agents like TDP43, FUS, UBQLN2 and more! 3) is the disease state a combined effect of singular mutations? polygenic?
I am excited to see how these questions get answered in the future! Thanks @RealSci_Nano for this twitter take over! Feel free to follow me @cytoskeletown to see where this goes! fin
[admin] Huge thank you to Jessica (@cytoskeletown ) for a wonderful week of science! Do give her a follow🥳 Watch the conversation between Jessica and @MySci_PK on @the_sciencetalk youtube channel. #UnderTheMicroscope #WomenInSTEM https://t.co/WGClqfC82H https://t.co/baUkV0pL7a
Sara Hernandez Mejias
[admin] "Harnessing Light at the Nanoscale" Please welcome @sarahmejias3 of @IMDEA_Nano for a smashing week of #materialsscience and #nanoscience More details in the podcast👇🥳🎧 #UnderTheMicroscope #WomenInSTEM #WomeninScience #sciencetwitter https://t.co/bMn3LuNInr
RT @MySci_PK: Follow along as our amazing team mate Sara takes over the most popular materials science account @RealSci_Nano 🥳
[admin] If you prefer to see this week's #RealScientist @sarahmejias3 of @IMDEA_Nano then watch her interview with @MySci_PK on @the_ScienceTalk #UnderTheMicroscope #nanoscience #materialsscience #sciencecommunication #WomenInSTEM https://t.co/k3ToqWPE3M
The scientific journey is exciting. After years of postdoctoral training, our curator @sarahmejias3 has the tools to work on her passion: studying the light conversion principles on engineered bio-hybrids. Her advice: never stop learning! https://t.co/Y0PShpNEje
Our curator @sara develops her research at @IMDEA_Nano, an interdisciplinary research institute with a collaborative and international environment. As she said in the podcast, IMDEA is a good place to work on and to grow as a scientists and as a mentor! https://t.co/eRWUW8eD5D https://t.co/Mi6TYynO9w
@sarahmejias3 said in the podcast: "the best thing about being a scientist is to work in your passion with the team you build. Seeing students learning is probably, the thing that I like most about my job". Check the rest of the interview in the link!! https://t.co/eRWUW8eD5D
Julien Barrier
[admin] "Nanoscience from the Birthplace of Graphene" Please welcome @JulienBarrier 🥳 who is @EPSRC fellow at @UoMPhysics #graphene #UnderTheMicroscope #nanoscience #materialsscience @the_ScienceTalk https://t.co/jh9FwysRWO
Hi there! I’m @JulienBarrier, a researcher in condensed matter physics at @UoMPhysics. Sounds vague? Follow the threads and hopefully by the end of the week you will know everything about this field of research!
RT @JulienBarrier: This week, I'll be talking over the @RealSci_Nano account to talk, day-to-day about my research. Check it out!
I'm studying condensed matter physics (CMP), and within this field, I'm working on electron transport in graphene and graphene heterostructures. I'll talk a bit more about the science in the coming days
I'm currently in Manchester (UK), the birthplace of graphene, but I haven't been there my whole life
Before Manchester, I studied chemical physics at @ESPCI_Paris in France. This is a small institution, enrolling cohorts of 100, with a curriculum at the crossroads of physics and chemistry
The curriculum @ESPCI_Paris is simple: a) it teaches experimental science, 50% of the time spent on hands-on practice at the bench b) it gives a mixed culture: physicists able to carry out basic chemical synthesis, chemists who understand the physical properties of their material
At the end of my MSc degree, I flew to California to study the phase behaviour of halide perovskite alloys in the lab of @MMfToney at @SLAClab
Halide perovskites are exciting materials, showing promising photovoltaic performances but are prone to phase instabilities leading to degradation and thus performance loss
There, I used X-ray diffraction to understand the degradation and phase-separation mechanism. It resulted in 2 papers:
In the first, we characterise the light-induced demixing. Under illumination, the material segregates into two phases, altering the performance of solar devices. It was published in @Matter_CP, and I contributed to the X-ray analysis https://t.co/a69hN0lQSq
In the second, we used X-ray diffraction (XRD) to understand the heterogeneity better. Before that paper, it was very hard to monitor structural heterogeneity at length scales between 1nm and 100nm. Drawback overcome with XRD. Published in @EES_journal https://t.co/Y2scygKCWW
I'm talking about the papers, but they can be quite intimidating to read because it's how we - scientists - communicate our latest scientific advances to the rest of the scientific community. Don't hesitate to ask questions here!
After this experience in characterising the physical properties of nanomaterials with XRD, I started my PhD in Manchester @UoMPhysics
Despite the notorious English rain, Manchester is a cool city: small enough that it's easy to walk/cycle everywhere, but big enough so that there are lots to do on the weekend
In terms of Science, Manchester is the birthplace of graphene (@UoMGraphene), so we have nice facilities covering the full chain:
Here, the National Graphene Institute is dedicated to basic research and fabrication of devices. Note the physics formula on the facade. https://t.co/3HElxXU7ON
Here, the Physics building is where we perform most of our electronic measurements. It is one of the 3 places in the UK with helium regeneration facilities https://t.co/LwGNCyGT3F
Finally, the Graphene Engineering and Innovation Centre is dedicated to transferring technology and innovation to the industry through startup creation and incubation https://t.co/8CUwHddOsH
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.@JulienBarrier back here! Let's talk about some of the particularities of the British research system
So I said I am currently an @EPSRC Fellow. What does it mean?
In most academic systems, a typical career path would be PhD > postdocs > assistant prof. > associate prof. > full prof. with naming differences depending on the country.
In the UK, it is similar, the typical career path follows PhD > postdocs > lecturer > reader > professor. But there's another way: fellowships.
The idea is that a career move from the lecturer stage would be decided by how much grant money a researcher brings to their institution. Postdocs are not used to apply for grants, so hiring directly at the lecturer stage can be risky for an institution
Fellowships in the UK are a way for early career researchers (postdoc level) to prove that they can bring grant money and therefore are worth hiring on a permanent contract (tenure)
There are multiple fellowships awarded after a competitive application process by both public and private bodies: EPSRC, Leverhulme Trust, Wellcome Trust, Royal Academy of Engineering, Royal Society, etc.
Right after my PhD, I was awarded the EPSRC Doctoral Prize Fellowship. It is a relatively small one but gives me my own research budget (consumables + travel) to manage and pays my salary. I am currently hosted in an existing group, therefore can't get large equipment.
The next career move would be to apply to other fellowships (longer, more budget). In some of them, the researcher can apply for grants. If granted, this is a very strong case for a lectureship.
One issue: they are very competitive. Much more than a usual postdoc: a) one needs to find a group to host them b) institutions can usually present only a limited number of applicants: it's competitive at institution level c) there's limited funding: competitive at national level
The main advantage is that it shows independence. I wrote my own proposal, follow my own ideas, carry out my own independent research, and manage my own research budget
On the + side, I'm considered a postdoc, therefore don't have teaching or administrative duties, and can focus on my research 100% (and writing proposals for the next step 😰)
What do you think about such a system? Would you like to have such opportunities? Or would you find it overwhelming?
Heya! @JulienBarrier here. Today, I want to tell you about the transition from chemical physics in my Master's project to condensed matter physics in my PhD
As I said yesterday, I worked on X-ray characterisation of halide perovskites at the end of my master's degree
It would have been a natural way to transition to a PhD in that field. And originally, that was what I did
In fact, I submitted a research proposal to my PhD supervisor at the interface between his expertise and my experience. This is how I got the PhD position
So I proposed to exfoliate halide perovskites and make van der Waals heterostructures with graphene and perovskites. For those interested about the proposal: https://t.co/o674j9Ln71
So I arrived in this lab in September 2018 and tried to do this. The goal was to make halide perovskite monolayers and then contact them with graphene to explore their electronic properties.
The issue is that these perovskites are already unstable as bulk crystals, I let you imagine how unstable it is when you manage to have a few atomic layers…
I tried several methods, but the halide perovskite would systematically degrade before it could be encapsulated with any other crystal. After 6 months, we decided I could not achieve the impossible, and we dropped this original project.
In hindsight, I'm glad I had the chance to try that direction! I think we lacked good chemistry methodology: some other groups focused on chemistry ventured into this direction and obtained pretty good results: https://t.co/LW0D0aQU59
The exfoliation method, which my group specialised in, yields good quality stable crystals (like graphene) but was not efficient for these perovskites. On that path, I learned a lot in microfabrication techniques!
After we decided to drop the perovskites, my supervisor suggested I took charge of a dilution refrigerator. The goal: measure electronic devices at temperatures 0.01 degrees above absolute zero.
I accepted since that was the natural direction I intended to pursue: a) fabricate perovskite, b) measure them in the facilities. Since I couldn't fabricate, I would measure other sorts of devices
Tomorrow I'll talk a bit more about dilution refrigeration, that's a fascinating technique!
Since I started measuring electronic devices, I found a few interesting phenomena involving the behaviour of electrons at low temperatures and high magnetic fields. More of this later!
So... this is how I moved from chemical physics training to being a condensed matter physicist, studying the behaviour of electrons at ultra-low temperatures!
Good morning everyone! @JulienBarrier here. Let's talk about cryogenics! https://t.co/a0GLa8pGbl
We use dilution refrigerators to cool down to millikelvin temperatures.
Why so? At low temperatures, atoms and molecules move around less: they are basically frozen. The only thing that moves are electrons, and we want to study their transport properties
There is another reason: at low temperatures, you get rid of perturbations from the outside world, and quantum effects can emerge. We expect new physics!
How low is a millikelvin? That's one thousand of a degree (C) above absolute zero, -273.15°C or about -450°F. Very, very cold! https://t.co/9EAQIbjkoH
To cool down a device, there are different methods. The easiest: liquefy a gas and place your device inside. Here Liquid nitrogen, at 77K (-195.8°C, -320°F) https://t.co/UrsD4PEVnt
To cool down further, one can use liquid helium, that boils at 4.2K (-269°C, -452.11°F)
The method to cool down even further is to pump on a liquid bath of helium. When atoms are pumped away from the vapour phase, the most energetic atoms (the warmest) leave the liquid and replenish the vapour. This effectively cools down the liquid helium
This method can achieve 1.3K with helium. That's already very cold!
If we want to cool down even further, we can use 3He, an isotope with 2 protons and 1 neutron (the usual 4He has 2 protons and 2 neutrons). Pumping on a 3He liquid can cool down to 0.3K
How do we cool down further? We mix 3He and 4He! This is done in a dilution refrigerator, an instrument that was imagined almost 60years ago!
The working principle is based on the dilution of 3-He in 4-He. To understand it, here is the phase diagram of 3He in 4He https://t.co/CGX0UX1Ibz
The most important parameter: below 0.87K, there is a forbidden region, and the two isotopes are only miscible for some concentrations
Close to absolute zero, one can get almost pure 3He (right side) and a dilute phase with 6.5% of 3He in 4-He.
The magic here is that helium is a quantum liquid, and we use all the properties of quantum physics to cool down! https://t.co/YGszXn2Mq8
On this left side of the diagram, 4He is superfluid (so has no excitation like phonons), and basically acts as an inert background for 3He. On that side, 3He is a fermion and the interatomic distance is controlled by its concentration in 4He
Important, below 0.8K, the mixture is phase-separated, like oil in water: the 3He-rich phase (concentrated phase) sits above the dilute phase
If we take atoms from the concentrated phase to place them into the dilute phase, they will split up but this needs energy. Guess where the energy comes from?
From temperature! The mixing of 3He in 4He is endothermic. That's how we cool. This technique was first proposed in 1962 and achieved experimentally at @UoMPhysics in 1965
Here are the first prototypes of dilution refrigerators, created by Prof Henry Hall https://t.co/GlULEejzjs
Here is a schematic of the inner circuit. The dilution occurs in the mixing chamber (MC). 3He/4He from the dilute phase are distilled in the Still. This pumps atoms from the dilute phase, forcing 3He to move from the concentrated phase back to the dilute phase. https://t.co/Ow7b1yaSml
This is a closed circuit: 3He atoms pumped away on the top come back to the concentrated phase through the thin line.
To cool down a device then, we bolt it to the MC and circulate the helium mixture, taking heat from the device to work!
Here is a picture of the mixing chamber in my setup. It is bolted to a plate, to which we attach all devices to cool down. The blue items are thermometers. The rings are heat exchangers that allow the mixture to flow to the still and the incoming, pure 3He to be cooled down https://t.co/kWhe1VE5Xf
In practice, the system is a tad more complicated, there are multiple plates that are cooled down to different temperatures, to maintain the whole system cold https://t.co/IwLloRNvkJ
Of course, we cannot leave the system in the air, it would never cool down. We place it in a vacuum can to isolate each element from one another and prevent heat leaks https://t.co/3E2ACzcpV1
For those interested in the history of dilution refrigerators at Manchester, there was a conference in 2015 on the 50 years of the first DR. Presentations here: https://t.co/fhKZjwW0GJ
Hi there! @JulienBarrier again. Let's talk about graphene electronic devices and how I measure them
I am studying van der Waals heterostructures made of graphene and other 2D materials. The principle: take several atomically-thin materials, stack them together and voilà! https://t.co/2k1l5ucSiT
For example, we like to work with graphene and hexagonal boron nitride, an insulator that protects a material to study (here graphene). The picture shows the fabrication process of such heterostructure https://t.co/8o5NWxdGnY
Once a stack is made, it is etched into a shape of interest, and metallic electrodes are added. The structure can be very complicated depending on the project's aim. Here the width of the purple strip is 1.5µm https://t.co/XpFM8qPxIb
All of this is done in a cleanroom, a highly controlled environment, where dust is minimal, humidity and temperature well calibrated
Outside of the cleanroom, we "bond" the device to a chip carrier holder. Here the silicon wafer is 5mm wide. This is a very precise activity https://t.co/7hxxiLsBjW
Under a magnifying lens, we deposit droplets of silver-charged conducting epoxy on the contacts created by lithography. We do this with a sharpened toothpick. Then, we connect these pads with gold wire to the chip carrier. Everything by hand!
The last step: placing the chip carrier in a sample holder, ready for measurement in the dilution fridge! https://t.co/osd6ozl1cc
Once the sample is loaded in the fridge, we can measure its electrical properties.
The principle of our measurement is simple: flow a current throughout the device, and measure a voltage drop at different contacts, using a variety of equipments to tune the properties https://t.co/K8vnF2DG6v
That way, we can measure a device's resistance and deduce some properties : the mobility (how much electrons are accelerated by an electric field), the mean free path (how far can an electron go before bumping into another electron or a phonon), etc.
The typical device has a transistor architecture: we connect it to a "gate", which is a metal plate below or above the device, that we can charge with electrons or holes
Because our devices are atomically thin, applying a gate voltage changes the energy level (the Fermi level) within the device, allowing to study the electronic response for different chemical potentials https://t.co/iH3pP89458
This technique of gating a device via field-effect is not possible in all materials: 3D bulk crystals will feel the field effect only in the surface, for example
but for 2D materials and van der Waals heterostructures, this is one of the most powerful tool!
For example in cuprate high-temperature superconductors (3D), different phases appear with different dopings. To change the doping, one needs to synthesise a new crystal, with a different chemical composition each time! https://t.co/EYhgTmaIuk
In van der Waals heterostructures, it became possible to change the doping via tuning the gate voltage: the same phase can be described in a continuous measurement! https://t.co/5Hweu55dMa
The doping level is not the only parameter to vary: we can change the temperature, apply a magnetic field to the device, apply different sorts of electric fields, etc. Some people use lasers as an additional tuning knob
Later today, I'll talk about our recent results in graphene superlattices, combining variation of the Fermi level (via gate voltage tuning), magnetic field, and ultra low temperatures. Stay tuned!
Hey folks! @JulienBarrier here! Let's talk about one of my recent projects: Brown-Zak fermions in graphene superlattices
If you sandwich graphene between two layers of hexagonal boron nitride (hBN), you'll get high-quality graphene. If now, one of the two layers of hBN is exactly aligned with the graphene layer, the magic starts
In fact, hBN has a similar lattice structure as graphene, but 1.8% larger. When aligning them, we get a long-range superlattice pattern, called moiré (like moiré fabrics) https://t.co/zAudK5uD1x
When measuring the resistance as a function of the gate voltage (therefore doping) of a superlattice device, we observe peaks. They correspond to features associated with the main graphene (0V) and the long-range moiré (other satellite peaks) https://t.co/Uq51TTkXV6
And in practice, the band structure is changed: the resistance features correspond to new mini-cones at high doping (in blue) https://t.co/RAYkA2DTO0
The physics is relatively easy to understand with a physics background; it is based on the Bloch theorem.
If you take free electrons, their band dispersion will be parabolic. If now you add an atomic lattice, gaps emerge, and the band can be folded in a Brillouin zone https://t.co/LhN9XVAMX9
This is the same when you add an hBN moiré to the graphene layer, the band folds (again) in a mini-Brillouin zone, smaller than the graphene Brillouin zone. Gaps appear, and resistive features are observed
Now let's add a magnetic field perpendicular to the graphene. If you study 2D electrons in a magnetic field, they will form orbits (quantised!), with a characteristic length scale that is the magnetic length lb: https://t.co/M5r5yZVcEM
The question we tried to answer is: what happens when lb becomes comparable to the lattice constant a?
Well, in a usual material, that would be hard to achieve: a magnetic length comparable to a few Å lattice constant would mean a magnetic field of 10 000T. The best magnets on earth achieve around 50T, so it wouldn't be possible
Not if you use graphene superlattices! With a superlattice constant of a few 10nm, you only need 30T to have a comparable magnetic length!
We did the experiment: placed a graphene superlattice device at ultra low temperature, in a magnetic field, and measured the resistance
Usually, the resistance of any metal exposed to an increasing magnetic field, increases as well
This was not the case in the devices we measured. The resistance increased roughly, but whenever the magnetic length became a fraction of the lattice constant, the resistance dropped
In terms of physics, that is something unexpected, the resistance should not drop, since the electrons follow circular trajectories, and should not contribute to electronic transport anymore
So we understood that whenever one orbit had a size of a few superlattice unit cells, the band structure changes. In fact, the combination of the magnetic field and the superlattice results in the emergence of new quasiparticles
Quasiparticles are a framework we use to describe the electronic behaviour in simple mathematical terms: instead of adding a loads of parameters in the equation, we use a simple equation, where the mass is changed to reflect interactions
We named these new quasiparticles the Brown-Zak fermions, in honour of two theoretical physicists, Brown and Zak, who studied the "magnetic translation group", a mathematical framework for superlattices in high magnetic fields
The physics is actually much richer than resistance drops. This is for example a map of the conductance as a function of the gate voltage and magnetic field. The conductance peaks for fractions of the superlattice unit cell, and decreases above https://t.co/PwVMYS03IZ
If you're interested, more details are available in our paper https://t.co/9OlBeasZ4y, + it's #OpenAccess
This is 100% fundamental science; it's really hard to think about any application for this
However, in condensed matter physics, it can take 50 years before blue sky research can be transformed into an application
Think about, for example, superconductivity. Discovered in 1911, it's only in the 1960s that people started fabricating superconducting magnets, used today in MRI!
Hi everyone, it's my last day on this account! I'll be happy to take questions on the science I presented or about the life as an early career researcher!
[admin] Huge thank you to @JulienBarrier for a smashing week of #graphene science, do give him a follow! @EPSRC @UoMPhysics @UoMGraphene @UoMSciEng Check out #UnderTheMicroscope podcast where Julien candidly speaks about his science. https://t.co/bKM9MBw989 https://t.co/2mbGpLOon0
Rebecca Katharina Pittkowski
[admin] "Boosting green energy, one reaction at a time" Please welcome @RPittkowski of @UCPH_Research #UnderTheMicroscope #WomeninSTEM #materialsscience #nanoscience #GreenEnergy #Scicomm #podcast https://t.co/qPY0IrjS0C
Hi from Hamburg. I am so excited to do this weeks takeover.🥳 My name is Rebecca (@RPittkowski)👩🔬 and I am a PostDoc at @UCPH_Research in Copenhagen🇩🇰. But today I am starting with a little impression from our current experiment at DESY @desynews in Hamburg/Germany🇩🇪 https://t.co/mH8Z2JKVLV
So, what is DESY @desynews? Or more general, what is a synchrotron facility? And what makes our #research so exciting that we happily work #nightshifts and on #weekends? #ScienceNeverSleeps A thread 🧵 1/5 @RPittkowski https://t.co/YU5EOyBbgi
DESY @desynews stands for "Deutsches Elektronen Synchrotron" and is a large scale research facility located in Hamburg. The PETRAIII ring at DESY, a 2.3 km ring underneath the city, was once the largest particle collider worldwide, but has since been rebuild to supply X-rays. 2/5
PETRA III is a storage ring generating extremely high energy X-rays. The electrons in the ring are accelerated to 6 billion electronvolts (6GeV) particle energy and race around the ring close to the speed of light. They can provide X-rays with energies up to 200 keV. 3/5
Scientist can use these high energetic and intense X-rays at ca. 40 end-stations, where different experiments and techniques run e.g. to study tiny objects: proteins, small nano-particles,interactions of matter, or look into thick samples, to study processes in e.g. a battery 4/5
We are currently sitting with a team from @jensengroup_cph at one of these end-stations (@p021_desy), and are shooting X-rays at small capillaries full of newly synthesized materials, to understand how the atoms are arranged in our nano-particles. 5/5
We finished this morning! After 48 h of experiments, with two sets of 12 h shifts - running on Chocolate, Cola and Coffee☕️ Nerves always run high at beam time, so the tiredness comes when everything is done. Now we are happy to get home to Copenhagen, just a 5h train ride away🚅 https://t.co/uKULfaSK9y
I will try to give you a little #glimpse of the experiments we were running the past days at the P02.1 beamline at DESY @p021_desy The experiments did involve a #robot 🤓🤖 and many, many tiny glass capillaries.... A #thread 🧵 with a robot #video 1/6 @RPittkowski https://t.co/ephy7qZXNH
First, we place capillaries filled with #nanoparticles (small glass tubes) on a holder, which the robot can later grab. This involves a lot of wax and steady hands, to place the capillaries in a straight way. In the picture you can see a sample rack full of capillaries. 2/6 https://t.co/jITlI7KkDx
Here you can see a sample spinning in the lab, to check if the capillaries are straight, or if we need to move them a little to even out any wobbling👩🔬- we can melt the wax again and angle them new 3/6 https://t.co/KSfcgLFQLy
The sample racks with capillaries go into the experimental hutch, the place where all the #Xray #action happens. It is closed off with heavy lead and once the X-ray beam is on, you cannot enter. So the #robot grabs a sample & puts it in the Xrays. see ultra cool robot video-4/6 https://t.co/i2RzoeWheI
Because we cannot enter with the beam on, there are a lot of cameras 🎥 installed through which we can double check that everything is running smoothly. Here a photo of a camera image, where we watch the #robot arm picking up a sample. 5/6 https://t.co/KkREYdE1L9
When the X-ray beam hits our capillary, the particles inside the capillary #scatter the X-rays. The scattering is detected by a 2D detector, and we can see such a pretty scattering image. We integrate the images, to get a diffraction pattern to analyze. More on that later 6/6 https://t.co/ufzKxTsX1T
Amazing news at University of Copenhagen today!! @UCPH_Research @ChemKUniversity. The #Nobelprize in #Chemistry goes among others to Morten Meldal for #Click chemistry 🥳🥳 I was planning quite day after beam time today, but instead there will be celebrations 🍾 /@RPittkowski https://t.co/8GKvSEBuvo
Maybe the followers of @RealSci_Nano will be able to get an #insight view of the celebration at the Chemistry department at H.C. Ørsted Institute today. What a coincidence that I am hosting the account from here this week #endelignobel https://t.co/4XjSXZngBt
The chemistry department of @UCPH_Research is celebrating this year's chemistry nobel laureate @NobelPrize Morten Meldal with an impromptu reception in our hallway. A well deserved prize for #click #chemistry and amazing news for the department @ChemKUniversity https://t.co/7VrokZ4A6C
How does an #impromptu #Nobel celebration look? The dean @katrine_science of the science faculty @science_ku and department head @PernilleHarris present flowers and congratulation speeches, there are Danish Flags 🇩🇰🇩🇰🇩🇰 and of course #Champagne What a surprising day at work https://t.co/mxb4nz4ffQ
RT @NobelPrize: “We are only scratching the beginning of our understanding of organic chemistry." Listen to our interview with Morten Meld…
RT @CHEMUCPH: Awarded the @NobelPrize yesterday - teaching MSc students in organic chemistry at 8:15 am today. #NobelPrize2022 #chemistry #…
Fantastic that #teaching is valued so highly here in Copenhagen. #BusinessAsUsual @CHEMUCPH https://t.co/hLRrPMBCRe
[admin] 📢 New Blog-post alert! Remember those three wishes ou scientists pondered with @MySci_PK? Did you ever wonder what the most common wishes were? Come and find out: https://t.co/5V0qRolAyY https://t.co/jCaWN7SCFT
After yesterday's Nobel celebration we are back on track . I believe I promised something on #data #analysis A thread 🧵on how we extract the data from our #robot beamtime @desynews @p021_desy and how we figure out the #arrangement of #atoms in our samples /@RPittkowski 1/6
We get these beautiful 2D images from where the #scattered #X-ray beam hits the detector plate. What you see below is the scattering recorded for LaB6 - not surprising that we use it as a standard for calibration when you look at the beautiful #rings 2/6 https://t.co/9TybK0Ljem
By radial integration we get a 1D diffraction pattern, which shows distinct Bragg peaks for each ring on the 2D image. I made a very boring #GIF where you can see how the #rings relate to #peaks in the pattern 3/6 https://t.co/zybBlmw2S8
Such a a beautiful #diffraction pattern we get for powder #crystalline samples. The #periodic lattice planes reflect the X-rays periodically which leads to interference. Maybe you remember #BraggsLaw 🤓 4/6 (image credit @kirsten_mj) https://t.co/ZLJgxMsBOz
We can identify many #crystalline compounds based on their #diffraction #pattern which serves as a kind of #fingerprint and can be compared to #database structures. There exist many databases with hundreds of thousand structures - a good start to identify your structure 5/6 https://t.co/I0rEXPwLuQ
But what happens when we #go #nano ? By downsizing the crystal we lose most of the periodic lattice planes - so no more beautiful rings💍or Bragg peaks 🤔Not to worry, we can still get structural information - from #PDF (not the #fileformat 📰) - but that deserves its own🧵6/6 https://t.co/088BSj3XGA
@drheaddamage Dioptas
Finally, the thread (you didn't know) you have been waiting for 🥳 "How can we use X-ray scattering to learn about the way the atoms sit in a #small #nanoparticle?" - lets use the Pair Distribution Function #PDF ! It's all about the neighbors 1/6 /@RPittkowski https://t.co/LzQLBXBwad
To get information from small #nanoparticles, where periodic lattice planes are rare, we measure the X-ray scattering to very large scattering angles. This is called #Xray #totalscattering. So we need to come veeeery close with the detector to our sample.😱😬 2/6
Again, we integrate our scattering image (check up older tweets), but we are not done yet. More data treatment is necessary. We use a #Fouriertransform and transform from reciprocal (Q) space to #real #space - and there we have it, our PDF 😍3/6 https://t.co/6Ayj3Q6Oze
We see that we have distinct peaks at certain distances. These correspond to specific #distances between #atom #pairs . And we can use the distances to characterize the atomic structure in our sample 4/6 https://t.co/Tm5lPix5RZ
The distances prominent in the example, agree with the atomic pairs in a metal phase, where the atoms are densely packed (face centered cubic). We can also #fit our structural #model to the PDF data to confirm - our particles are #metallic and have an fcc #lattice 5/6 https://t.co/ZqlEl5t5tj
But we can get more #information from the PDF. As the PDF shows the interatomic distances in the particle, it tells us when there are no longer characteristic #distances, so the particle probably ends. This can give an idea of #size - we have around 1nm metal fcc particles 🥳6/6 https://t.co/Jo9JhRCeZO
A little more on #postdoc #life in #Copenhagen One of the things I love is the bike infrastructure My 10 km commute every day is great for exercise and a clear head after work🚲 Especially if sunny like today. 🌞The video is from this morning, out of rush hour /@RPittkowski https://t.co/QdP7mynYdr
You can see how popular cycling is by the overflowing bike parking in front of the department @CHEMUCPH this morning https://t.co/8mqLD1NXUd
Another thing I 💕about working @CHEMUCPH is the great #working #culture. We enjoy #lunch together with colleagues @jensengroup_cph everyday and there are regular trips to the coffee machine ☕️ I have to say, it tastes best out of our #CHEAC mug 😍@HEAcatalysis /@RPittkowski https://t.co/hbDMTv1SSg
As this is my last day of the #TwitterTakeover, I want to end with a 🧵thread on the #materials we are looking at. Why are we so interested in the structure of #small #nanoparticles ? 1/8 /@RPittkowski https://t.co/WXDsbqiqdc
Small particles have the advantage that many of the atoms are located on the particle #surface and are not #hidden inside. We want such a large number of surface atoms, because we use the particles for #electrocatalysis 2/8 https://t.co/GqaMfERLNV
What is an #electrocatalyst ? Basically a catalysts that makes an #electrochemical #reaction easier. So we are talking about reactions where #voltage and #current play a role- #electricity is key 3/8 https://t.co/5WhCLut81e
One example that highlights the power of #electrocatalysis is splitting water into hydrogen and oxygen. When we talk about #green #hydrogen, renewable electricity is used to power this reaction. #hydrogen can then serve as a #storage for e.g. #solar 4/8 https://t.co/UVm2fWShvY
To release the energy from the #hydrogen, we can than use a #fuelcell to react #hydrogen with #oxygen - and we are back to #water and #electricity. In this #process we lose some of the #electricity. So my research focuses on making #electrocatalysts #efficient and #stable 5/8 https://t.co/3QgwV2vvTO
A while back I made a video explaining this #hydrogen #cycle for students, but I still think it is a beautiful resource to explain #electrolyzers and #fuelcells Feel free to check it out: https://t.co/8xyW7QiGfz 6/8
What I would like to understand is, how does the #structure of the #catalyst relate to its #properties and how can we follow how the structure #changes during #catalysis. And for me #Xrays are my favorite tool. Because #Xrays dont need to work in #vacuum 7/8 https://t.co/WRS1gsyGQb
With all these beautiful #Xray techniques - #XRD, #PDF, #SAXS, #XANES etc. we can actually #look into real #reaction environments and follow how #nanoparticles change in shape, atomic arrangement or oxidation state. To understand the #structure during the reaction 8/8 https://t.co/1fe34IP4cg
Thanks for following along this week! I really enjoyed myself & I hope you had fun too. If you are up for more #synchrotron trips and #nanomaterials, we will visit @DanMAX_MAXIV in a week with @jensengroup_cph & @HEACatalysis. I am signing out, enjoy the weekend /@RPittkowski https://t.co/xJR8Y5oEvS
[admin] Huge thank you to @RPittkowski of @CHEMUCPH for a wonderful week of science with a super special surprise celebration of Nobel Chemistry win!🥳 Do give Rebecca a follow! #UnderTheMicroscope episode ft. Rebecca links below 👇🎧 https://t.co/9tPoZk0bpc
Jose Luis Ocana Pujol
[admin] "Thermodynamics doesn't care about you" Please welcome @jose__op of @ETH_en 🥳 On 195 episode of #UnderTheMicroscope, Jose speaks candidly about his research, scientific journey and much much more! #materialsscience #nanoscience #scicomm https://t.co/zR8JflW7ng
RT @RealSci_Nano: [admin] "Thermodynamics doesn't care about you" Please welcome @jose__op of @ETH_en 🥳 On 195 episode of #UnderTheMicr…
RT @jose__op: Se vienen cositas en @RealSci_Nano
Good morning! It is 9AM in beautiful (although today quite gloomily foggy) Zurich. My name is Jose and this week I will curate this account. Today I will start by introducing myself (@jose__op), my department (@ETH_Materials), my group (@LNM_eth) and the city of #Zurich.
Good morning Guten Morgen Guete Morge (🇨🇭!) Buenos dias Bon dia (in Catalan, as the @the_ScienceTalk podcast host @MySci_PK knows and said in this week's podcast 👇👇) https://t.co/pfHW1iSrZW Wishing everyone an exciting Monday full of science!
In our lab, mornings start with some coffee grinding. Some of our master's students did some parametric study on the best parameters... https://t.co/gIBj7RBMcG
And this is how the actual coffee machine looks! I have to say that this is not the best coffee that this beautiful work of engineering can produce, but the parameters need to be readjusted every time someone brings some new exotic coffee from their vacation! https://t.co/BQk9Ox0deE
Now that I am caffeinated and done with my Monday morning meeting with my supervisor, time to talk about my science and vital journey!
I was born in Tremp, a small town in the Catalan Pyrenees. The town rose to fame in 2016 given its resemblance to the name of some former US president... @playground https://t.co/avE1WXQNz7
Although quite rural, the area is definitely connected to science: It is a Geopark (@GeoparcOrigens), a recognition given by @UNESCO to areas with an special geological interest. An Astronomy research centre and a starlight recognition to our clean skies https://t.co/cT54vWEH1N
So, how did a guy from the Pyrinees betray his favourite mountain range (left, July) and end up in the Alps (right, November)? The answer isn't that straight forward, involves science, and some intermediary steps are needed to explain it... I will continue tweeting in a while 😉 https://t.co/DF00wGIwEu
I started my scientific journey by studying Nanoscience at @UABBarcelona. Yes, a bachelor in Nanoscience. Something new at the time (and still not very common today), I was in fact the second promotion to the bachelor's and in the only place in Spain where one could study it.
The fact that recently @UDC_gal started a similar program and the high access requirements tell me that there is interest for such an education at a bachelor's level. Also quite interesting that only universities in the "Spanish periphery" seem to opt for such programs...
Despite all this, I was quite critical of the education that I was getting. I even thought about quitting. But then I thought: Am I deceived by the way science gets taught at my university or with the university system overall? To find out, I applied for an Erasmus grant...
And I ended up in another European university offering a bachelor's in #nanoscience: @AarhusUni_int, in Denmark! Besides being a lot of fun, I was super happy about the education system there, and the differences were noticeable...
In my campus in #Barcelona there is a synchrotron: @ALBAsynchrotron. To visit it we had to register 6 months in advance. At Aarhus University their synchrotron was in their basement. Accesible by anyone using the elevator. One could just go and ask the people around about it.
I went back home to finish my studies, but I decided that, if I had to do a master, I'd rather do it abroad. But hey, that last year we designed great T-Shirts that I still wear nowadays! https://t.co/e1VsnlKXnO
Studying Nanoscience as a bachelor was a truly #interdisciplinary experience. The bachelor was new, and biology lecturers complained that we thought too much as engineers, while engineering professors tried to find biology related examples to motivate us.
Upon graduating, some went on to study more #bio topics. I now have classmates studying drug delivery (and involved in #RNAvaccines), while some got into #neuroscience. Others chose to stay more in the #nanomaterials field. Class reunions are thus a lot of fun :)
What about me? I was a bit upset that the only career opportunities were in fundamental research, so I decided to go for a more generalistic master's. Since I had always been interested in #sustainability, I decided to follow the steps of a friend a met during my erasmus...
And I joined a master on #Physics with a focus on #energy and #sustainability in beautiful #Amsterdam. (picture from @unsplash) https://t.co/n4MJNObgNH
In this program for @UvA_Amsterdam and @VUamsterdam we were allowed (and most importantly encouraged!) to take courses in fields other than #Physics. Having been studying for 1 more year than my classmates (Spain has 4-years BSc) I decided to use the opportunity to the fullest.
I even joined a half a year-long minor in consulting, science and society called the Tesla minor (nothing to do with the fancy cars of current @Twitter owner). https://t.co/9lzcas7aon
I spent 6 months working with a theoretical physicist and a neuroscientist trying to fix the model that suggested that all Africans would be using #Solar Ovens for cooking by 2030. Both thermodynamics and sociology dictated that this was unlikely to happen. (pic from @craiyonAI) https://t.co/g3ISKJ6KAm
Following this, it was time to do my master thesis and I ended up at @_amolf, in the @3dPV_group. What a great time I had there! A truly magical place, a well-organized institute, with lots of support from the non-research staff and great mentoring!
There I worked on #2Dmaterials and I was finally allowed to operate a Scanning Electron Microscope myself to see my structures. It wasn't always easy, and sometimes I ended up singing in front of the microscope to deal with the frustration... https://t.co/MTDBDOEm91
My time at AMOLF was so fulfilling that I ended up deciding to try to pursue a PhD, despite the fact that I had gone to Amsterdam to find an alternative career path in the first place! Life is full of surprises... @AltAcChats
Due to a combination of lucky coincidences, I got an interview for a PhD at @ETH_en in the @LNM_eth out of more than 200 candidates. I talked a bit more about it during the podcast. https://t.co/m8wCMSSHLG
And I ended up getting an offer to start a PhD at the best university in Continental Europe! This REALLY taught me the importance of #networking but also that, behind any success, there is a ton of dedication AND a couple of tons of luck! https://t.co/SHHb9kGetB
Nothing is for free though, and looking in retrospective my adaptation to #Zurich could have gone smoother. I joined a Materials Science (@ETH_Materials) department without a background in materials.I was in a metallurgy group but knew little about steels. Mild #impostorsyndrome
My personal life also suffered it a bit. Zurich is a beautiful city, but coming from #Amsterdam and #Barcelona, it felt a bit dead (especially on weekends). https://t.co/sRU0n0A5wz
It makes sense though. Having such beautiful but also accessible sites nearby, few choose to spend their free time in the city. There is this @ETH_en joke that there are only two kinds of PhD students: the outdoorsy type and the gamer type. And you find none at the bars. https://t.co/mIZjXv4Nfs
But stereotypes are often wrong. And so was the idea that I didn't fit in the department. Talking to people that had studied in the department I discovered that they had also often been misunderstood due to their interdisciplinary background! https://t.co/zSV1DGcaw8
In fact, most professors at @ETH_Materials are NOT material scientists by training. And in the colloquium organized by @SAM_at_ETH I learned that research in my new department ranges from teletransportation to colourful chocolate! https://t.co/tQJHKHKepo
There will be more on chocolate tomorrow when I talk about all the very different but very exciting research that we do at @LNM_eth. For now, I just leave you the paper in case you want to do some exotic #TrickorTreat tonight :) https://t.co/WFy6Als4Sd
Enough tweeting for now, time to celebrate #Halloween (or #castanyada, if you are in Catalonia). I close here the thread on my #SciencePath and how it took me from the Pyrenees to the Alps passing by flat Amsterdam and Denmark. https://t.co/cUDF2sXmm7
@RPittkowski @KITKarlsruhe Looks beautiful
#NightPoll Today I have written about how pursuing my research meant I had to live in 4 countries. What about you? How do you think the "go abroad to learn" culture influences the #mentalhealth of researchers?
@kovacsjulie absolutely true. might be a generational thing but also a hierarchy thing, though.
Guete Morge! This morning I will be taking part in a public speaking workshop given by the 'Communication academy' of ETH called 'presenting science to non-expert audiences' I will try to show how it is and what we can all learn from it. #SciComm https://t.co/mQ9ZlnOjYh
@JulieStenken It was actually an external public speaking couch!
She started motivating us with this video. https://t.co/SCjblXadKA
We had to come up with 20 skills/strengths in 5 min. No one could actually finish the assignment. Before we enter the room for the second and last section in 2 weeks, she will check whether we did the homework: a list of ONE HUNDRED skills that we have. https://t.co/ukCNDDi0jb
We also learned some stress management techniques like square breathing, and some voice warm up exercises that were a lot of fun!
We ended up practicing by presenting a research paper in 3 min. Mine was qbout Thermophotovoltaics, on Thursday I will tweet about this topic. For now, I'll just say that I started with the line: "If someone tells you that you are shining, they mean that u are hot" https://t.co/uqvWA8cDp8
It is almost 16:00 and some (mostly Swiss non-research staff) people are already leaving their workspaces, but I just arrived at mine! ETH has two main campuses, but luckily they are connected by a direct bus that IS FREE! Time for the link! https://t.co/JWJMK1lnpK
At @LNM_eth we fabricate and study #nano things. This afternoon I will be showing the tools that allow us to do so and that we are lucky enough to have within 50m of our coffee machine! https://t.co/RIj6voUGHd
These are our film deposition techniques. Using either very high temperatures or a strong magnetic field, we "transfer" the material to whatever we want to deposit on. This way we are able to deposit layers as thin as 1nm thin. https://t.co/aPXW6ni4dO
All these machines operate in very high vacuum. Inside these chambers, there is up to 1000000000 times fewer molecules than in normal air. This is achieved by very good isolation + ultra efficient vacuum pumps, making this room quite noisy 👂🙆
The sound is heard in this (sorry for the bad quality!) video. The purple light that we see is plasma, caused by the acceleration of gas molecules towards our material. The plasma then goes towards our substrate. This becomes apparent in the video when I open the shutter. https://t.co/214Rb6lOX0
We can also change the material that we deposit by making this plasma react with an atmosphere of a certain gas that we introduce in the chamber. This #blender scheme that I presented on @metaconference tries to illustrate this technique, called "reactive sputtering" https://t.co/fJbV4WPyt0
We also have a range of #3Dprinters to deposit more exotic shapes. This is our self-made printer. With it, we are able to deposit metals and semiconductors down to 100nm! This work actually made it to a #nanoscale cover: https://t.co/sZGFXCd6gk https://t.co/4HkkIbEeek
Once the materials are fabricated, it is time to examine them to learn about their properties and structure. We use many different tools for that, and we have many of them in our own facilities! Roughly, they can be divided in: x Optical x Mechanical x Microscopy
Optical characterization: We can study how light interacts with our materials and structures. Do they reflect light? Or transmit it? How much? We also use light for Raman Spectroscopy, which can tell us what material is it, whether it is crystalline and even if it is stressed! https://t.co/TGBfPPiqJZ
Stress means something different to material scientists than to the rest of mortals🧐 When one pulls a material (compressing it, for example) we call that stress. We use Reflectance Anisotropy Spectroscopy to study this! https://t.co/rI0FHZuiN3 https://t.co/MwH4nkKgnP
Our favourite mechanical characterization technique is Nanoindentation! Basically, there is a tip that "pokes" the material with a certain force, and we can see how much of a mark it leaves, indicating how tough the material is. https://t.co/r4yeAJqLck
This is a great video showing how nanoindentation works from our former senior scientist and micromechanics expert, Jeff Wheeler. https://t.co/G29DRPr3L7
Finally, there is microscopy! We of course have tons of optical microscopes, the kind of microscopes that one uses at highschool and science toys. However, that is typically not enough to see the very small structures that we fabricate.
For that, we need an electron microscope, which uses electrons instead of light for imaging. We are lucky enough to have one in-house that can easily image things as small as 5 nm! https://t.co/p0QHxtXFiG
This great machine also has an Electron Dispersive X-Ray Spectrometer incorporated. When electrons hit our material, they generate X-Rays with an energy characteristic to the kind of material. Therefore, the microscope can tell us the chemistry of the material!
The machine incorporates a Focused Ion Beam. Ions (electrically charged atoms) are focussed into a very small beam that can be used to draw and cut the sample. This panel from @MingChen101 shows how small these cuts and drawings can be. https://t.co/qPkgm649hy https://t.co/iLmbYUgsEs
#NightPoll At what point in your career were you allowed to operate expensive fragile tools such as electron microscopes yourself/ at what point do you allow students to use your tool?
Enough tweeting for today! Tomorrow I will finally get to talk about metamaterials! Good night, gute nacht, bona nit!
@PalmaLab_ Really? Very interesting! Most nanofab tools (EBL, PVD etc) can also be quite costly though!
@MicrotoPico Agree. I also personally don't understand how sitting in lectures with power points for 2 more years is supposed toake anyone better at handling instruments...
Turns out that 1/3 or the respondants have at least rather negative feeling about how going abroad to do research affects the lifes and minds of scientists! I personally expected it to be a smaller share. Keep tuned for more insights into the sociology of our +3000 followers! https://t.co/JdsLkAsWbW
@DrClaireDancer @MetamaterialsUK Thank you! I will try to do my best to explain what a metamaterial actually is, even if somehow I still so far failed to make my mother understand it 😅!
@DrClaireDancer @MicrotoPico how short is short? here at @ETH_Materials, both bachelor thesis and master project at 12 ECT (so about 2 months full time)
Guten Morgen, Bon hour, Buongiorno, Buen di! Today I wish you good morning in every official language in Switzerland, can u identify them all? Today we have an 'optical metamaterials subgroup' especial breakfast, and I'll be using this opportunity to tweet about metamaterials!
What is a metamaterial? My humble attempt to explain it in this thread! 👇👇👇
"Typical" materials derive their properties from their chemistry, from the elements in them. For example, glass is transparent and brittle cos it is silicon and oxygen atoms. In metamaterials, the properties are instead derived from their "designed/engineered structure".
Look at these images. This is what we mean by "structure". Do you see the periodicity? That a certain pattern repeats? This is the engineered geometry, this is what gives the metamaterials their properties. https://t.co/MUfOVW40V0
To circumvent copyright issues, I asked @craiyonAI to draw me a "metamaterial". From what I know about artificial intelligence, the fact that it comes up with this kind of structure indicates the kind of images typically published with the marker "metamaterial". https://t.co/Td3RLDGJgP
However, there are many objects around us that have a "designed structure" and aren't metamaterials. Think about a wheel! On top of that, the structure of a bone looks fairly similar to the images of metamaterials... The "structural" definition is a bit more complex! https://t.co/d16nwE7Gat
This designed structure needs to be way smaller than the property it is designed for. In the case of optical metamaterials, this is straightforward: the designed geometry needs to be described by distances several times smaller than the wavelength of interest. https://t.co/VWjUacEaeJ
That is why, although the idea of negative-index metamaterials was developed in the 60s, it wasn't until 40 years later that it was achieved and ONLY with microwaves, which have rather long wavelengths. We need to fabricate fairly small structures! https://t.co/RfyfiFtJc3
There is still another component to the definition: Metamaterials show properties that are not found (some downgrade it to "not very common") in nature. Let's see some examples:
Negative refraction. Light changes direction when it goes from one material to the other, aka refraction. In nature, refraction is "always positive". We all know what a straw in a glass of water looks like. With negative refraction, it looks quite different... https://t.co/zJNTiaq3Cq
To the best of my knowledge, negative refraction metamaterials are what started the field. My personal fav example of how this looks is the example with a swimming pool that I found in @drskyskull, check this blog post for a more detailed explanation: https://t.co/FRVzK7c4JO https://t.co/hsStwYatuG
Negative Poisson Ratio When you compress a material in one direction, it typically expands in the other one. This is measured by the Poisson ratio. If you compress a negative poison ratio material in one direction, it also compresses in the other!
The great @TEDxTalks from Bas Overbelde shows this (1:40-2:20 approx) and more about mechanical metamaterials. Some recognition to him, he was the supervisor of @GiorgioOliveri4, who gifted me the metamaterial that I showed at @the_ScienceTalk! https://t.co/tVWkKgGldw
Following the "negative" properties of metamaterials, there are even metamaterials that behave like they had negative density! This is found in acoustic metamaterials and pretty far away from my expertise, but still fascinating!
To sum up: Metamaterials are engineered metamaterials that derive their exotic and non-common properties from a designed structure much smaller than the scale of these properties! Next, I will tweet about some metamaterial research in our group!
This morning I tried to explain what are #metamaterials. Now it is time to showcase the metamaterials that we study at @LNM_eth ! I will begin with some #mechanical #metamaterials before diving into optics. https://t.co/c9b8nQWLwB
Metamaterials show "abnormal" properties, so to understamd them, we first need to look at "normal" material properties! So, to feel the beauty of this metamaterial, we ned to talk about the stress-strain curve! https://t.co/H4cTf3gOzg https://t.co/EBB0Qote5t
I touched briefly on what stress means yesterday, and tomorrow I will talk about the stress-strain curve more in detail since I will be with first-year students in the lab during a Praktikum. https://t.co/JpCSp2gFIH
For now: stress is the force that we apply to a material, and strain is the deformation that it causes. The stress-strain curve shows that and this is how a typical one looks. Initially, the relationship is proportional. Then, it is not, and eventually, the material breaks. https://t.co/QQdfBNgxaM
Compare both stress-strain curves: the mechanical metamaterial (on the right) shows TWO areas where the stress-strain relationship is proportional! That is our special abnormal property. How is that possible? Because of its topology! https://t.co/tjOW16NNCZ
What is topology? It is a full field of math that deals with the geometry of continuous bodies. As long as things are connected, it is the same topology. Only "holes" matter. This video summarizes the basics way better than I ever could! https://t.co/05ga0bbKfD
This video summarizes the two different topologies of the #mechanical #metamaterial, which was produced by #3Dprinting. The paper by Marius and @FabianMrBlack was the group's first excursion into #mechanical metamaterials! https://t.co/if9i6dIiNt
Now time for #optical metamaterials! Some people in our group, lead by @paunessa, try to look at large-area scalable optical metamaterials. What do we mean by that?
As mentioned, the designer structure of metamaterials needs to be way smaller than the wavelength of interest. If we talk about visible light, this means patterns of less than 100nm! This typically leads to very long fabrication times. https://t.co/glICjnq5bG
We look at fabrication approaches that allow us to build #optical metamaterials with this #nano feature sizes in hours and not in days, and which are compatible with the large-scale fabrication used in industry. How? We are looking at two approaches:
(1) Disordered metamaterials In the metamaterial definition thread, I made you look at the periodicity. But we can also have metamaterials where the features are disordered, meaning that they do not repeat! https://t.co/2UgshgTIDj
Some examples: Structural colours using network metamaterials https://t.co/ChrrqNJRu6 An outreach explanation on how it is actually #bioinspired: https://t.co/IOP6IwOvyw https://t.co/wwBDiqZrJV
Tailored super-absorption at different wavelengths by chemical engineering, from @Jelena_Wohlwend. https://t.co/kNLbEn69kk https://t.co/Yu6TTXPlKl
Zero-index disordered metamaterials https://t.co/WsSTj3xenO The interaction of light with matter can be described by two indexes, for the electric and magnetic fields, respectively. So zero-index=no interaction!
The examples exposed above were fabricated using various kinds of magnetron sputtering, one of the machines that I showed yesterday. We deposit two elements at the same time and, if the elements don't dissolve or react with each other, we get disorder! https://t.co/LEFsFUNu6h
But what if instead of doing that we deposit one material at a time and on top of each other? We are getting to our second approach: (2) Multilayered metamaterials
I will go into detail about them tomorrow since that is my topic AND we do not only do multilayers for #optical metamaterials. For now, I leave you with the thread of @LNM_eth lab about my latest publication! https://t.co/fBJsSo8kBw
The reason why I decide to wait to explain everything about my beloved multilayers... Today we are celebrating 'october fest' in the department! (Yes, in November. Yes, after Halloween. Material Scientists are confused animals) https://t.co/M5kdiAgEM9 https://t.co/sGRsiWuGbc
#NightPoll (1) What is the impact of the push for #networking in research? Positive or negative? (2) Is the importance of #networking in a researcher's career exaggerated or undermined?
Good morning! #Zurich is, for some months a year, the perfect ANTI Lalaland... Another day of fog! https://t.co/ip8jp4yt1H
All the tweeting about Zurich and its weather reminded me of this book. I started reading it upon a friend's recommendation and turns up that about 50% of the story happens in Zurich since it is where the ministry of the future is established. https://t.co/QDGlqZvT6Q
If reading about Zurich isn't ur thing, I still recommend the book if: 1 You like the idea of science fiction BUT unscientific sci-fi gets you nuts. This is hard, realistic sci-fi 2 You are broadly interested in sustainability and climate change but prefer fiction to manifestos.
What is on the plate today? In the morning I will focus on multilayers and their applications: from hyperbolic optical #metamaterials to self-healing materials! In the afternoon I will show how I teach 1st-year uni students about materials and their stiffness using experiments
I could be more impressed with how artificial intelligence draws every scientific topic... Here is what @craiyonAI thinks that a multilayer is 😅😅 https://t.co/7cF6CJXGVq https://t.co/RjPVvgBD2D
Thin films and multilayers! Thin layers (or films) allow to change the properties of an object while only using a tiny bit of another material. e.g? Chip bags! They are made out of opaque plastic, but if you open them, you will see that the inner part is reflective: Aluminum! https://t.co/55fLA5d4x3
At @LNM_eth we develop and use optical tools to study thin films. https://t.co/rI0FHZuiN3 https://t.co/Co1BTOQa4l
But what if instead of putting a thin material on top of a thick one we stack thin materials one over the other and repeat it many times? That is a multilayer and turns out that it opens the door for a lot of material property engineering. https://t.co/TmV6MpcRj4
Many tools are coated with multilayers to make them tougher, resistant to the heat produced by their operation (think about a drill) and more. Multilayers are also used to make good mirrors for X-Rays. And, to some degree, also solar cells are multilayers! https://t.co/tGOPwe0lMp
A couple of examples of multilayer work at @LNM_eth: (1) Reactive multilayers. If we combine the right materials that "like" each other, upon ignition, the components of a multilayer will react to form a single layer.
Reactive multilayers have been proposed for a variety of applications, but my favourite one is self-healing films. Thin films can break and then your device is dead. But what if there was a multilayer system that would locally release heat where the fracture happened? https://t.co/PDBaqJrHo4
Some of our work on reactive multilayers (1/4): https://t.co/FAIbXfC3O6
Some of our work on reactive multilayers (2/4): https://t.co/p9ScWr7810
Some of our work on reactive multilayers (3/4): https://t.co/aQNcnCbJkr
Some of our work on reactive multilayers (4/4): https://t.co/O4IVeO3geN
This was work on "chemical" multilayers. Now an example on how multilayers can be used for #optics: (2) Hyperbolic metamaterials https://t.co/I0009wClQY
For an accessible explanation of what hyperbolic metamaterials are, I recommend the first 15 min of this video: https://t.co/5YyyI4WxpP
There are basically two kinds of optical materials: metals, which reflect light, and dielectrics, which transmit it. Hyperbolic metamaterials close the gap between these two kinds of materials: they are metallic in one direction and dielectric in the other!
This extreme change in the optical properties depending on the direction can be exploited to get, for example, a specific kind of negative refraction. https://t.co/v2XEwxvbxP
Hyperbolic metamaterials have lots of proposed applications. They are superabsorbent, blacker than black! They allow us to see and detect very small things with regular light, with no need for electrons! https://t.co/IKo0kqlpA5
More examples! Hyperbolic metamaterials have been proposed for energy solutions (thermophotovoltaics, radiative cooling) and for disease treatments (hyperthermia). These applications require materials to deal with high temperatures, though. That is a problem for multilayers.
The components of a multilayer can react with each other at high temperatures if the elements like each other (see reactive multilayers!). If they don't, they can try to get away from each other, which doesn't happen if they don't have enough energy (temperature!)
So: 1 Hyperbolic metamaterials are kind of a "third state of optical matter" since they behave like dielectrics or like metals depending on how you look at them! This gives them awesome optical properties! https://t.co/lKUB5MNKGR
2 We can obtain Hyperbolic metamaterials by stacking thin films on top of each other aka fabricating multilayers! This means fast, scalable fabrication! https://t.co/9ij2VOxkzx
3 Many applications of Hyperbolic metamaterials require working at high temperatures (hundreds to thousands of Celsius). However, multilayers tend to degrade at those temperatures... https://t.co/Tsd2vNFf8Q
My research focusses on how to solve this compromise! Are there hyperbolic metamaterials stable at 1000C? Why do multilayers degrade? Can we make their optical properties resistant to this degradation? https://t.co/kuu3SPSOwH
RT @the_ScienceTalk: Learn more about metamaterials in less than a minute as @jose__op of @LNM_eth @ETH_Materials @ETH_en explains in this…
A close up of the negative Poisson ratio metamaterial that I showed on @the_ScienceTalk https://t.co/tq8k3yyORK https://t.co/OXgiT6AhfT
Time to write about the Young's modulus and how I teach it in an experimental exercise. In Spring 2020 I had to give an ONLINE experimental exercise, so why not a TWITTER experimental exercise? https://t.co/FKmlAMtVsa
This video from @efficiengineer is a very good introduction to Young's modulus (or elasticity modulus, E-modulus). It is basically a measure of how much force one needs to deform a certain material aka how stiff a material is. https://t.co/ikxEMKruqo
We visualize the E-modulus in the strass-strain curve. As I tell students, it is probably the graph that they are gonna see the most during their #materialscience studies. (Could be an exaggeration though, probably no one measured it). https://t.co/4G2gBrb60O
The experiment is simple: pull some weights on a beam of material and measure how much it deflects. From that one can calculate the E-modulus. When labs were closed, I sent them this video for them to understand the experiment: https://t.co/2L6WsN2Sy2 https://t.co/LfMnoyAubu
They typically fit data for the 1st time. Of course, the true objective of the exercise is for them to get an intuition of what a high Young modulus means. That's why they have to compare PVC with steel. And then comes the question: why are some materials stiffer than others?
It mainly boils down to two things: the kind of atomic bond (covalent? metallic?) and atomic structure (crystalline? amorphous?). To visualize that I always bring along some short experiments. And I have a youtube version of them all!
1. Simply stretch a plastic bag to see the difference between covalent and intermolecular bonds. The #corona version of it was: https://t.co/xPpzrJBzbv
2. Cleaving silicon wafers as an extreme example of the importance of crystallinity (and anisotropy)! The 2020 version: https://t.co/2qTYlGJe48
3. Breaking aluminium stuff by alloying it with galium to learn what an alloy is. The lock-down (please don't do it at home) version: https://t.co/UFneb4ftIM
During lockdown, I challenged them to be creative and reproduce the deflection experiment at home before sending them some data so that they would still do the analysis. Some of the results were very impressive: https://t.co/ejAb8u1duH
But when I think back about that time and this remote teaching experiment, I always remember these pictures 🤣🤣🤣 https://t.co/b6VUPiJxd6
Bon dia! Some close-up of how a typical optical materials breakfast looks like! https://t.co/UaqqgxS7oL https://t.co/WblaUyvhdI
Some people at @LNM_eth are baking experts, and some other are extremely creative thinkers. This is how our 'cheese cake' bake off looked! https://t.co/L2glqs5Xz9 https://t.co/SsRLvGndbx
@sanjanacurtis How difficult it is to get tap water is frustrating BUT I think the volume scales the same way for all drinks. Espresso vs American coffee etc
On Wednesday I tried to define a #metamaterial. Now it's time to define #metals, which should be way easier, right? Spoiler: even in a #metallurgy group @LNM_eth, not everyone agrees! https://t.co/oVrvdroruq
First a list of "high-school science" definitions that don't really help us. The "Metals are reflective": Yes but not all reflective things are metals. Not definition friendly. https://t.co/WWQymNOCY8
"Metals are ductile and malleable, easy to work with": Not necessarily. Good luck working with Tungsten, which is definitely metal. This article tells a bit about how hard making the Tungsten filaments that we used on lights was! https://t.co/p4O1hDPeOL
Until the 19th century, a metal was simply "a dense element". The first known metals were #HeavyMetal after all! After 1809, light metals like sodium and later aluminium were discovered. So don't use density as a definition, you are wrong by 2 centuries!
Actually even nowadays different disciplines use different definitions. Astronomers consider that everything that isn't Hydrogen or Helium is a metal... So you are all metals! And so is the air that you breathe! https://t.co/9Fjj0oWkXx
https://t.co/jcG0X3nooG
A pretty popular definition among the #Chemistry community is that metal is a substance whose oxide is basic. (Basic means something else in chemistry! Basically the opposite of acid. Alkaline is a better word, but alkaline #Memes are boring) https://t.co/I6aQCJ06if
What I call the "bonding definition" seems to be the most popular among material scientists and solid-state physicists: metals are elements held together by metallic bonds aka by the electron cloud. https://t.co/YxNNNcQ7MO
The problem with the bonding definition is that it is not too compatible with quantum mechanics: the three kinds of bonds are defined by "where the electrons are", something that QM doesn't allow! In reality, most bonds are a mixture. https://t.co/Mzb9ZqBkIk
In #optics, we define #metals as media with negative permittivity. This requires you to be comfortable with the idea that something might be a metal or not depending on the wavelength. https://t.co/GDOa2DOzvS https://t.co/jcOrMbdeQD
So far we have covered what are the wrong definitions of metals (reflective, malleable), what are outdated ones (dense) and which are acceptable as long as you only talk to your immediate-field community. What is the agreeable definition of metals then? https://t.co/JW6be4LoyF
The one that makes the most sense to me and that seems to be accepted by physicists who looked into it is related to electronic conductivity. "Metals conduct, non-metals don't...at 0K" https://t.co/UfDgPfw9Sz
So only at 0K (-273 C) can we know what a metal actually is. If you are dissatisfied with the answer, you can extrapolate it and say that in metals the conductivity decreases with temperature, while in other "conductive" solids like semiconductors it is the other way around.
However, this extrapolation fails again to describe metals since: (1) the same happens in electrically conductive liquids. (2) the case of superconductors needs to be taken into account.
If you made it this far and are disappointed... SORRY! I was too when I found out! Defining metals is far from trivial, but looking into it is a good #science exercise! https://t.co/mvjSNcF0DO
#SelfPromotion A blog entry on @MasScience, a Spanish-speaking outreach blog, in which I elaborated on this. The images were drawn by #design students based on my text, in a #scienceandart project! https://t.co/onEEQRfheL
Twitter is pretty disordered atm, will this end up making it less useful for its community? If it behaves like the multilayers in this article, not at all! That's why @elonmusk recommends taking a Material Science course... https://t.co/WLAakXDWDY https://t.co/IxgRS8rD3x
Last day curating this amazing account! If you enjoyed the content, make sure to follow me on my personal account @jose__op and my lab @LNM_eth. We sometimes have #popscience content, as this thread about #SquidGame perfectly exemplifies 👇👇 https://t.co/Hx53hShgGO
Yesterday I had to take a break from tweeting because I am moving to a new apartment. Professional scientists have become experts at moving across borders, and, according to the results of this poll, most of them are positive about it! https://t.co/VEzEHOB2v1
RT @martinmbauer: Brilliant demonstration: when squeezed, metamaterials can compress in two orthogonal directions rather than expand in one…
If you have been folowing the account his week, you might have guessed that I have a thing for definitions and debates over definitions. What is a metal? https://t.co/gvdEhVcjwg What is a metamaterial? https://t.co/512aaQLhbN And now: what is a cake? https://t.co/UfZUcJkEYW
That is the discussion that delayed our lab's (@LNM_eth) baking competitions. Do cakes need to be sweet? Are all cakes flour based? Are all cakes layered? Are all cakes round? (and much more)
Maybe the reason for this discussion is that we discussed it in Switzerland, a country known for its polyglotism: Turns out that @Wikipedia defines it differently in different languages! In French, for example, salty cakes pass the filter: https://t.co/LLC2wmnVfj
In german the distinction seems to be what recipient is used for baking. https://t.co/LI45GDTA3E One of the most popular dishes in Switzerland is Flammkuhen, the "Alsacian pizza" (which infuriates Italian speakers, the other big language in Switzerland). Is this a cake? https://t.co/TeFhH5zKaS
I felt like, if that is a cake, my mum's traditional "tortilla"/Spanish omelette cake should be considered. Some pics of the one I brought to a dinner party yesterday. https://t.co/beXolDx7bb
Besides definition wars, which illustrate Gedankenexperimenten (thought experiments) quite well, cakes can teach us a lot of science. Later today I will use this amazing #ScienceCake to talk about my paper. https://t.co/lclaMVclJ5
Imagine that you design the perfect cake. Due to the combination of different layers of ingredients, it will have awesome unrealistic properties. A #meta cake! But: will the structure withstand the temperatures needed during baking? Thread on my paper 👇 https://t.co/IxgRS8aA1x https://t.co/qJ07Qw3Ss4
Instead of a cake, we designed a near-perfect absorber. Less than 0.1% of the light hitting it can escape it! How is that possible? By disorder! Turns out that having the layers of ingredients intermix a bit makes an even better cake! https://t.co/ZYWO62T585
1st lesson: it's not always worth it to find a fabrication technique that avoids intermixing. Those techniques are way slower and don't necessarily improve their properties. A step towards scalable, large-area #metamaterials. https://t.co/yz7r83zUWX
A material with such a high absorption would be great for solar energy solutions such as thermophotovoltaics... if it would withstand high temperatures. That's why the next step was to put it in the oven at different temperatures. https://t.co/nuVaM6u3PQ
High temperatures mean different things to different communities. In metallurgy, we typically compare the "homologous temperature", which is the temperature divided by the melting point of the material. Everything above 30% of the homologous T is considered high temperature.
Turns out that our metamaterial still has awesome properties at almost 50% of its melting point, very very hot! However, when we cut the cake baked at that temperature and look at its structure, the lower layers are gone without affecting its properties. https://t.co/sECh1DbeXO
And when I say "cut and look", that is exactly what we do. This tweet plays with that concept, exemplifying what we do with a focussed ion beam (FIB) and an electron microscope (SEM) at smaller scales: https://t.co/A3i6TTxtxN
So our cake still has its abnormally cool optical properties at high temperatures, even though the structure has began to degrade. How is that possible? Yet another prove that disorder isn't necessarily a bad thing! https://t.co/Kc0ZaKHdxE
The structure of the cake only degrades in the lower layers in this regime. The upper layers are untouched! We know because we cut alternated cutting a bit more of the cake with taking pictures, and reconstructed all the images in a #3D tomography! https://t.co/vmbJXtBP8q
So, why does the cake start breaking at the bottom? Understanding that could help us identify why the degradation is happening and what is driving it. We did simulations on our 3D structures to find out, and we compared how important the different driving forces are. https://t.co/qFayMxsLCQ
There are basically three reasons for degradation : 1 dissolve in each other (not here) 2 move to try to minimize the area of one element that is in contact with the other 3 move to minimize how stressed they are. Most literature focusses on 2, but we find that 3 is dominating!
The cherry on top of the cake is to confirm this experimentally: if we change the stacking order, we can change where the instability starts: now it starts on the top cos a different force dominates. And top of that, the evaporation temperature also changes! Double cherry! https://t.co/ICNaWcSsf9
To find out more about what metamaterials can teach us about baking... https://t.co/IxgRS8aA1x https://t.co/ZdC9lK1iKo
This is not the sweetest research carried out in our lab recently though! https://t.co/0cQHokpiv4 https://t.co/XWPCcaOT5R
I still don't know what kind of job I want to do after I finish my PhD. But at least I found the answer to what kind of job I do not want: I don't want a bullshit job! (and they are way more common than we want to admit, even among "blue-collar" jobs. https://t.co/Fk9pfZ4Xx6
BS job="a form of paid employment that is so completely pointless, unnecessary, or pernicious that even the employee cannot justify its existence even though, as part of the conditions of employment, the employee feels obliged to pretend that this is not the case."
I promised that I would talk about career opportunities after the PhD and other @AltAcChats using a university-organized event that I attended this week. Well, I was recommended not to, sorry! However, this book (50% read atm) is helping me clarify that.
"Bullshit jobs" by David Graber is my second and last reading recommendation. https://t.co/SlvEk45jhA
If you do not have time/will to read the book, check out this video: https://t.co/OiX9eN5Bal
That's it from my side! It was truly a lot of fun to curate this account this week and tweet about metamaterials, metals and more. A big thanks to @MySci_PK and the @the_ScienceTalk team for the great work! If you want to keep in touch, follow @jose__op and @LNM_eth. Adéu! https://t.co/7Ou2MjSumK
[admin] HUGE thank you to the amazing @jose__op for a smashing week of science full of coffee, meta materials and so much more! Do give him a follow! https://t.co/LJSoXxymcV
Andy Soder Anke
🌟Artificial Intelligence meets Nanoscience🌟 Please give a warm welcome to this week's curator @SodeAndy from @jensengroup_cph https://t.co/erOaXTb3c3
Have you told us yet where you like to listen to your #podcasts ? https://t.co/6dmXxVpGzk
Hi I’m Andy, I will this week introduce you to a world of materials chemistry, synchrotrons and machine learning (ML). I will tweet live from New Orleans where I attend one of the largest ML conferences in the world, NeurIPS. Finding my research interesting?Follow me @SodeAndy
or Mastodon: https://t.co/T8nPN8HbJl
I am this week attending NeurIPS – one of the largest machine learning conferences in the world! NeurIPS is short for Neural Information Processing Systems. 2905 papers are accepted for the conference and additional papers for the 60 workshops associated with NeurIPS :O 🧵
The NeurIPS website: https://t.co/GzKdU7Cs1h In the machine learning community, it is more common to publish in conference proceedings than in journals. NeurIPS papers have a large impact: https://t.co/SCdihH76tC
If the paper is not accepted in the conference, you can send it to workshops that are more specialized. I am especially interested in the AI4MAT workshop, where we (@EmilThyge) present 2 posters. https://t.co/PhaTW817Dh
I am also interested in other similar workshops like AI4SCIENCE and AI4Phys. https://t.co/RSa0Ie6PB9 https://t.co/WqAnHiFvWu
The first invited talk at NeurIPS is about to start. "Are Large Language Models Sentient?" By David Chalmers. #NeurIPS2022 https://t.co/3g3qJFSzW8
Today has been full of talks about graph-based machine learning (ML) What is graph-based ML and why is it important for chemistry? 🤔 https://t.co/P3FjIANoP0
Graph-based ML uses the concept of nodes and edges to represent your data in a different way than traditional ML. For example, a chemical compound can be represented with a graph by assigning the atoms as nodes and the atomic bonds as edges, connecting the nodes.
Nodes and edges can contain multiple attributes! 😲 For the example of chemical compounds, nodes and edges could contain such attributes as atomic numbers, valence electrons, and atomic distances.
Here we describe a metallic nanoparticle using graphs. The nodes are assigned atomic positions and numbers, and the edges are assigned distances between neighboring atoms. Edges exist exclusively between nearest neighbouring atoms. https://t.co/ygXmTOaSWx
Why do we need machine learning to analyse x-ray scattering patterns? 🤔 An x-ray scattering pattern is like a fingerprint of the chemical species. So, let’s zoom into a crime scene and follow the work of a detective…. A 🧵
What does a detective do when he/she finds a fingerprint? He/she gathers suspects! He/she gathers fingerprints! He/she compares the fingerprints with the fingerprint he/she found on the crime scene :O https://t.co/J4xEQWAKQz
We can do the same with x-ray scattering patterns! We simulate our suspects' x-ray scattering patterns and compare them to our measured data! 👊 However, if the database is large and we have to go through every entry, this is a very time-consuming process. 😑 https://t.co/K1h6SgU3VK
Instead, we can use supervised machine learning! From the chemical species and their x-ray scattering patterns, we train an ML model. This ML model can predict the chemical species from a dataset within a second!😲 https://t.co/YjVofoOpYm
But what do we do if the chemical species is not in our database? 🙃 We have tried to address this issue with our ML model, DeepStruc, which I further explain here: https://t.co/WCxA30cZKs https://t.co/uYDDDZAuMB
Synchrotrons allow us to measure x-ray scattering data fast! 🥳 In-house instruments are beginning to achieve quality x-ray scattering patterns within hours, but for synchrotrons, we can achieve quality data with second-resolution. 🧵
A previous Twitter takeover @RPittkowski has explained the use of synchrotrons here: https://t.co/IvWWAVHrSO
When we measure more data, we need more efficient tools for data analysis! 🤔 This is where machine learning (ML) comes in helpful! ML is super fast analysing data and often orders of magnitudes faster than traditional minimization techniques like least-squares refinements.😲
Can we understand how the machine thinks? 🤔 While the Machine is finding trends in large datasets that we, humans, cannot find, they are often still a black box. By opening the black box, we can begin to discover new science. This is referred to as explainable ML. 😏 🧵
In this thread, I explain how we have explored the use of explainable ML to analyse x-ray scattering data. https://t.co/SBXuvocujB
Whereas we with conventional approaches can refine a structural model to x-ray scattering data, now we can, with explainable ML, get an estimate of how much each atom contributes to the goodness-of-fit. 😲
Today, I’m presenting our paper “Extracting Structural Motifs from Pair Distribution Function Data of Nanostructures using Explainable Machine Learning” with a poster to the #AI4MAT Workshop at #NeurIPS2022. The work is about using explainable ML to analyse x-ray patterns! 😳 https://t.co/cfnKzWVcBn
Paper: https://t.co/xOd3AIl0Wi GitHub: https://t.co/Ngr0NwaMm4 Thread: https://t.co/SBXuvocujB
My colleague @EmilThyge is presenting our paper “DeepStruc: Towards structure solution from pair distribution function data using deep generative models” with a poster to the #AI4MAT Workshop at #NeurIPS2022 The work is about solving a structure from an x-ray pattern using ML!😳 https://t.co/ClqA1udny4
Paper: https://t.co/xOd3AICBNQ GitHub: https://t.co/iqLwUwh0Zn Thread: https://t.co/WCxA30u2Ms
#AI4Mat has been kicked off at #NeurIPS2022 https://t.co/FvExTT1WPF
X-ray scattering allows us to see the atoms! 😲 In my research, I have used x-ray scattering to study the atomic structure of nanomaterials, disordered materials and ionic clusters. But how can we use x-rays to study the atomic structure? 🤔
Follow the explanations by previous Twitter takeover @RPittkowski https://t.co/3idSozZfKa
We are 4 PhD students attending @NeurIPSConf from @jensengroup_cph supervised by @kirsten_mj and @raghavian @EmilThyge @UlrikFJ1 @fupperlidt https://t.co/CWVmSTKtjI
This week, I introduced you to the combination of materials chemistry, synchrotrons, and machine learning👊 If you found my research interesting, follow me on Twitter: https://t.co/PGuvFBMcbG Mastodon: https://t.co/T8nPN8p2vd Thanks for this week, now I will fly back to DK ☺️
@BhriguTheFirst @RPittkowski That is difficult! Normally the bottleneck in the analysis is to identify the structure. Fortunately, we have the last few years designed machine learning approaches which can predict the structure from a PDF. We can refine the structure afterwards.
[admin] Thank you so much @SodeAndy for an amazing week of science (and we hope you had a good flight back 😉)! Follow him for more cool materials science and machine learning tweets! https://t.co/88kyOvjqFb
Claire Dancer
[admin] 🏺Shattering 10,000 year-old ceramic recipe 🏺 Please give a warm welcome to this week’s real nano scientist @DrClaireDancer https://t.co/fwDnYLF02u
Hello everyone! I'm very excited to be taking over the @RealSci_Nano account this week. This one is promising to be quite a whirlwind with a little bit of everything in my academic life - not typical, but at least you'll get to see the breadth of activities I'm involved in!
First up, let me introduce myself and tell you a bit about me. I'm @drclairedancer and I'm a Reader (the level between Associate Prof and Professor) at the Warwick Manufacturing Group @wmgwarwick at the University of Warwick @warwickuni in Coventry in the United Kingdom.
My research group work on ceramic materials for a whole range of applications and I'm involved in a wide range of other activities including being the Co-I of the UK Metamaterials Network @MetamaterialsUK.
During the week I'm going to tell you about me, and how I got here, about my fascination for ceramics, and about how metamaterials can be made. Along the way I have a lecture and a tutorial to give, a whole load of end-of-term meetings, and a bunch of other activities.
At the end of this week you'll be tagging along owith me to the @MetamaterialsUK "Metamaterials in the Real World" event @NPL! This is a showcase of a whole range of Outreach activities network members have developed, followed by our advisory board meeting.
First though my inbox is calling, and I have a quiet hour to get through some of the messages at least. Coffee at the ready! Back later when I'll tell you about how I ended up as a materials scientist at @warwickuni
Well, some emails got sent, others got deleted, and in what I feel may be typical for this untypical week I did an interview for a film @wmgwarwick are making about what it's like to work here! Can't wait to see the final version! https://t.co/FEnsY5TrYw
So, let's tell a bit of my story. I grew up in South Wales, near Cardiff, and knew from quite an early age that I wanted to be either a physicist or an engineer - ending up as a materials scientist seems quite natural now, but I didn't know anything about the subject from school.
After school I went to the University of Cambridge to study Natural Sciences. This proved to be an amazing thing for me as the course structure there is really why I ended up in materials rather than physics as I'd planned.
At Cambridge you don't choose your science specialism straight away, in first year you do maths and 3 other broad sciences. I chose physics and chemistry, and then for the 3rd opted for "materials and mineral sciences" - sounds interesting enough for my third choice, I thought.
It took less than half the first term for me to realise that materials was my subject. We learned about symmetry in crystals, and how they can be studied and understood from the placement of atoms, to the microstructure of grains and defects, up to their macroscopic properties.
We learned about metals, ceramics, polymers, and composites, and how materials are characterised. And I've never really stopped learning - I find materials science fascinating, and I love how understanding materials helps me understand the world. I have @cumat to thank for that!
I made some amazing friends at Cambridge, and had the most incredible four years including a summer on an ERASMUS project at ETH-Zurich @ETH_Materials where I decided I wanted to do a PhD, but I wanted a change from the Cambridge bubble.
So I took the not particularly radical path for of moving to the University of Oxford @OxfordMaterials. Mostly due to the project there which was exactly what I wanted to study, as it had been the subject of my 3rd year project. So what could hold such fascination? More later…
Back from giving my lecture - one of my favourites! We teach a degree apprenticeship here @wmgwarwick - the students work for their sponsoring companies and come to campus for block teaching a week at a time. Intense but very popular way to study. https://t.co/tiuJq8xoS8
We have a lovely shiny bright red building to teach them in too. Today I was teaching a 3rd year lecture on ceramics. It focuses on properties of ceramics through the window of their applications - I think it's surprising quite how many variations there are!
My favourite is probably the ceramic knife. Always quite a surprise to those who haven't encountered these - but they are really excellent knives! And I have this Kyocera video https://t.co/HRtbNg99UC which is excellent for learning about how they are made and how to use them!
@JoFeanelwa @wmgwarwick It is an easy one to direct people to that's for sure!
So, returning to my doctoral studies. The material which fascinated me is what I still believe is a genuinely incredible material called magnesium diboride.
MgB2 sounds like nothing special, but in 2001 a prediction that it was a superconductor was verified experimentally, and the superconductor research community exploded into a frenzy. They're an excitable bunch anyway but this material was quite extraordinary😁
The reason? That simple formula. Magnesium and two borons. No non-stoichiometric complex oxides. No arsenic or thallium or rare materials. Simple, available to buy from chemical suppliers - and with a superconducting transition temperature of 39K.
So this seemed like an absolute dream compared to the alternatives! And there was a huge drive to make MgB2 into wires, to use in MRI scanners. So lots of people were doing MgB2 research, and finding good, if not exceptional, performance.
To me as a materials scientist the microstructures didn't look great, and it felt like this was a material which wasn't living up to its potential. There was a big gap between what was easily achievable, and what would actually be technologically useful enough for industry.
So with all that activity going on around me I embarked on a project to look at how to process MgB2 to get the best properties. It became apparent in my first year that really the processes being used to make the MgB2 wires and pellets from powders weren't very effective.
Under the microscope they still just looked like powders, because really they were. The process of solid-state consolidation of ceramics which we call "sintering" wasn't happening at the temperatures being used. But going too high in temperature made it decompose. https://t.co/TesnOLQFgZ
So the ultimate question of my project became "Does Magnesium Diboride Sinter?" And after a lot of work I came up with an answer - yes! But not easily. And not under ambient pressure.
To get MgB2 to sinter you need a reducing atmosphere (or at least not an oxidising one), uniaxial pressure, and a moderate temperature. And if you get it right you can get fantastic properties. One of the pellets I made achieved a record magnetic performance at 20K. https://t.co/SmXNz6lJm1
And so that was where I ended up at the end of my doctoral studies, with a very good understanding of how to process a rather awkward, water and air reacting ceramic which was great for a particular purpose.
But I was a bit fed up of awkward, and understand ceramics more generally, and to do that I wanted to study some "conventional" ceramics. So while MgB2 was the start, it was by no means the end.
I'm going to sign off there - but tomorrow I'll tell you more about ceramics and why I've ended up devoting my research career to how to make them more effectively and efficiently. See you tomorrow!
Good morning everyone! It is rather chilly here in the West Midlands today. And there are rumours of snow coming later this week, which is always a dramatic experience in the UK - we grind to a halt when it snows!
One final note on MgB2 and Superconductors left from yesterday - if you want to read more I hugely recommend this book by my incredible friend @SusieSpeller - it's written in a really accessible way, but without compromising on scientific accuracy. https://t.co/Sea32MhAYt https://t.co/wLUKtsQxgR
I managed to snag a copy last week when I was in Oxford and get @susiespeller to sign it - and read it on the train home! I suspect it's one I'm going to be lending out though, as it's a good book for people beginning work on any functional ceramics, not just superconductors.
Today is rather less busy than yesterday; mostly I have meetings with various types of students, so I think I can stay warm in my office and talk to you all about ceramics.
So perhaps to get started, let's have a little quiz. Which of these is a ceramic? https://t.co/GAVvG0oYyO
Which of these is a ceramic?
@philjemmett https://t.co/993XU93YRV
Well, I have good news for all of you - you are all correct! https://t.co/8PCf4uOxEN
Yes, these are all ceramic materials - but most people don't think of them all as the same type of material. That's because the ceramic class of materials covers a huge range of materials types, which have really quite varied properties.
So what makes them a class of materials which we can group together if the properties are varied? Well one behaviour is common to them all: the mechanical properties.
Ceramics, unlike metals and polymers, are very brittle. This means that they deform only very slightly (and reversibly at that) before they break (fracture). Under normal conditions we do not see the irreversible deformation (plasticity) which we see in metals and polymers.
Ceramics can also be rather hard to work with because of a statistical scatter in their strength from one sample to another. This is because fracture in a ceramic material is caused by tiny flaws inside it which can't be accurately detected by non-destructive methods.
The flaw which causes failure will nominally be the largest one, but must also be orientated correctly in the sample to be able to cause a crack to go through the material in the right direction to cause it to crack.
It is not possible to specify the strength of a ceramic part - I can't say a ceramic will definitely withstand a certain level of force on them, for instance. We can only specify that they will have a 95, 98, 99% chance of failing under that level of load.
All of which makes ceramics a bit tricky to design with mechanically. And often we need to avoid placing them in situations where cracks are likely to open - i.e. where there are tensile (opening) forces on the cracks.
But if we can do that we reap the benefits. Ceramics are incredibly durable, and very chemically inert. They can be used in extreme environments where no other material can be. Often the "material of last resort" - but without them we wouldn't be able to do all sorts of things.
Silicon solar cell - most definitely ceramic, but not much confidence! Teapot - most likely made of porcelain ceramic, as the majority knew. Helmet made of boron carbide, which can be shaped and is very effective. And brick: probably one of the most familiar ceramics around.
@jose__op No no no!! Definitely wrong!! 😁
Wow, today has been busy! Part of the problem with travelling away from campus during the week is balancing the time for meetings on all the other days. And with a module to teach all of next week it's been quite tough to squeeze everything in.
Today has been a bit of an out and about day - and it's freezing so big coat required! First I headed up past the still frosty pond to the main building to teach a maths tutorial on differentiation to my first year engineers. Already the last tutorial of term! https://t.co/jGDUQlYGgV
Then I headed over to the building where I'll be teaching next week as I wasn't sure how to find the room. This is the Lord Bhattacharyya building, named after @wmgwarwick's founder - it's an enormous building! And has a pretty Christmas tree up! https://t.co/UJfhFCSoIc
After lunch came an exciting project supervision meeting - in person, in the workshop, with the real 3D version of @wmgwarwick Outreach supremo @philjemmett! This is our main workshop, it's a huge space but the scale of some of the manufacturing processes we study require it! https://t.co/7YFs2qtuVP
Our student is working on making some of our "bendy wood" samples in a more systematic way - we have a theory about how the pattern relates to bendiness. Samples are cut, how to test them is an interesting question - more work to do next term! https://t.co/hHbvumnHZP
Obviously had to grab the chance to get a video of the laser cutter in action! And some of the samples. And I also grabbed the things I need at the @MetamaterialsUK Network Exhibition on Friday - looking forward to showing off the fancy new setup! https://t.co/AS4xyYMZ6a
Here's the video. It's incredibly quick! https://t.co/PD3DQGx1hP
I'll talk more about my work on metamaterials on Friday but if you're curious to learn more in the meantime previous @RealSci_Nano curator @jose__op told us all about them just a few weeks ago! Start from this post to learn more: https://t.co/6EI36BPSo2
[admin] Huge thanks to Claire for telling us all about ceramics, meta materials and her research journey! Do give @DrClaireDancer a follow 🥳 You can still watch conversation between Claire and @MySci_PK on our YouTube channel. #UndertheMicroscope https://t.co/dKsrWluFtb
Ashok Keerthi
[admin] ✨Graphene Nanotunnels - Welcome Onboard!✨ Join us in welcoming the last curator of 2022 - @AKeerthi03 🥳 #UnderTheMicroscope #graphene #SciComm #materialsscience #nanoscience https://t.co/RwlpgCaFqU
Hello #NanoScience lovers, I’m, @AKeerthi03, a researcher working on tiny tiny materials and architectures (as you know, #nanomaterials ) at the University of Manchester @OfficialUoM @UoMGraphene @UoMChemistry
Hello, everyone. Let me start by telling you a bit about myself. I am born and brought up in India, a rural village @Bollikunta near to a city called @Warangal in @Telangana state. (1/9)
I studied https://t.co/1h1cI4KKle (undergraduate degree) @ https://t.co/p0HtGDPGg1 University Arts & Science College, Kakatiya University, Warangal. One of the finest college in the region and my all time favourite place on the earth😍(2/9)
Obtained my master’s degree (https://t.co/4ASfUWWicg Chemistry) from University of Hyderabad @HydUniv School of Chemistry. One of the finest chemistry departments in the country with excellent teachers/scientists @TPR @TJ @AN @RamacharyDB @GautamDesiraju (2009) (3/9)
My turning point to choose #Science as career was my https://t.co/4ASfUWWicg days @HydUniv and a reasearch internship (SPIC) #IGCAR Kalpakkam. This motivation led to get my PhD in organic materials from @ChemNUS @NUSingapore working with Prof Suresh Valiyaveettil @chmsv (4/9)
My route to academic life continued, first PDRA position at Max-Planck-Institut für Polymerforschung @mpi_polymer. I had an opportunity to work and collaborate with amazing scientists @KlausMuellen @FaselRoman @XinliangF @MartinBaumgarten @LapoBogani (5/9)
Finally landed in Manchester (not that smoothly!) on the smoothest material, #Graphene (@NobelPrize 2010) research for my second PDRA position @UoMGraphene @UoMPhysics in 2016 (6/9)
A game changing moment in life, an Organic Chemist in to a traditional condensed matter physics group - entirely different skills and tools which I never had experience with. This adventure led to ground-breaking Science in collaboration with #Smartest people @UoMGraphene (7/9)
A dream come true moment, June 2019, awad of #RamsayMemorialFellowship from @SCIupdate, an early-career (academic) fellowship, enroute to #independentPI in the @UoMChemistry @OfficialUoM (8/9)
So many wonderful scientific collaborations across the globe and working experience with brightest people is only one-side of the coin. Ofcourse, there are many (&many) failures in terms of research experiments, fellowships & grants applications, anotherside of my #Academic life.
RT @MFM_MOF: Dr. Keerthi (@AKeerthi03) is a pioneer in 2D materials, polymers and graphene nanoribbons... check out this tweet to know more…
Now I will be talking about all wonderful science (#nanosciecnce) that we have been working at @UoMGraphene @UoMSciEng @RoyceInstitute @OfficialUoM https://t.co/5S8RW8OzrC
1. Such an exciting observation, “Frictionless flow in 2D channels” with @radhaboya and our team @UoMGraphene These 2D channels are narrowest artificial channels made from graphene and other 2D materials. Full story @PhysicsWorld thanks to @isabelledume for nice #newsstory https://t.co/UqP76rirVC
Gas transport in atomically flat nanoslits made from graphene and boron nitride is much faster than predicted by Knudsen theory https://t.co/78SLLaqWFp. @Nature Nature 558, 420–424 (2018) https://t.co/lBUW0hbljO
2. Soon after realizing quantum phenomena with gas molecules at room temperature in Angstrom-scale 2D channels, we studied ion streaming https://t.co/rH6oLU3T7j in collaboration with our #French team @LydericBocquet @TimotheeMouterde @AlessandroSiria et al from #ENS, Paris https://t.co/P6o2bOsH77
Transistor-like electrohydrodynamic effect could help advance the emerging field of “iontronics” https://t.co/JjgN68KaiI thanks to @isabelledume for putting it in nicely in @PhysicsWorld and @radhaboya @UoMGraphene and Timothée @NotTimothee @Nature
another news cover, "Controlling pressure-driven ionic flow by voltage at molecular scale" https://t.co/mVBNdplHS1 via @physorg_com
Do you wonder how we make these narrowest artificial 2D channels with utmost precision & explore the 'unseen' Science from ultra- confined "empty space" or "2D tunnels"? All possible at the birth place of #Graphene, #NationalGrapheneInstitute, Manchester @UoMGraphene https://t.co/FQDDGT2Dpj https://t.co/XGTqcMLaPh
#NationalGrapheneInstitute @UoMGraphene at the Manchester @OfficialUoM, is home to state-of-the-art nanofabrication facilities, pericularly, #Cleanroom fabrication where explore (exfolitate!) 2D materials to one-atom thick sheets. How we do that? see images below 👇👇 https://t.co/m6CIKnrQMe
And below is the fabrication flow if you are keen to know device design https://t.co/XUdjZuf8I0 https://t.co/Gly9QhN0rz
3. Curiosity based investigations continued, what else can travel through 2D-channels (Water☑️, Gases☑️, Ions☑️) with unusual flow? Can a polymer go through these 2D tunnels? for this we teamed up with highly talented @cees_dekker @Wayne_YangWW @tudelft on DNA translocation https://t.co/FQDDGT2Dpj https://t.co/fIWYGfSdpA
Here is the link to our work on "DNA translocation through 2D channels" Advanced Materials https://t.co/9jYuBASsMC theory and simulations by @aksimentievLab at UIUC https://t.co/6JAdFSRnMm
@CredentialedRSS @cees_dekker @Wayne_YangWW @tudelft @UoMGraphene @radhaboya @UoMPhysics Thank you, a good suggetion for future studies!
In my research career, Ramsay memorial trust fellowship (Early career research fellowship awarded by The Ramsay Memorial Trust) played a crucial role towards independent researcher #newPI at Manchester. And the University of Manchester’s Presidential Fellowship to build my group https://t.co/a9OvR1Q1JH
The Ramsay Memorial Fellowships were instituted in 1920 as a memorial to Sir William Ramsay (1852-1916). The Fellowships are offered to postdoctoral chemists who are in the early stages of their career, so that they may initiate a programme of original and independent research
https://t.co/BVJrWh6PRp
I am very much thankful to all funding agencies who had supported our research thus far. Thanks to @EPSRC for #newhorizons award, @royalsociety for Research Grant and International Exchanges awards, Ramsay memorial trust @SCIupdate, conference awards from @RoySocChem https://t.co/yvQ9D1ysKz
[admin] Huge thank you Ashok for a wonderful week of science. Do give @AKeerthi03 a follow! Missed #UnderTheMicroscope ft. Ashok? No worries, we got you covered! 👇 #materialsscience #nanoscience #scicomm #sciencepodcast https://t.co/ftU3vDANTF
2023
Lisa McElwee-White
✨we got the INK - Nanoscale 3D printing✨ Please welcome @McElweeWhite of @UFChemistry for a week full of the chemistry behind nano 3D printing INK🥳 and and, watch the latest episode #UnderTheMicroscope to know what all is coming your way this week😉 https://t.co/iRdYLOUKB6
We are the @McElweeWhite group @UFChemistry, your curators for the week. We develop chemistry for the deposition of inorganic films and nanostructures. We work across a variety of techniques that use heat, light, electrons or ions to drive depositions. https://t.co/LtN0cG27eY https://t.co/nzYfruoTij
You can do nanoscale 3-D printing in a scanning electron microscope (SEM). The focused electron beam writes the structure from chemical precursors (the "ink") in the chamber. But the chemistry is critical. See this review by the @McElweeWhite group. https://t.co/8aKId3EGtu
Not just electrons -- you can also do nanoscale 3-D printing with a focused ion beam (FIB). But is the chemistry the same for ions and electrons? Yes and no. See this paper by @McElweeWhite. https://t.co/tduS9TsPbF
RT @RealSci_Nano: ✨we got the INK - Nanoscale 3D printing✨ Please welcome @McElweeWhite of @UFChemistry for a week full of the chemistry b…
Don't want to use electrons or ions for nanoscale printing? How about light? See this paper by @McElweeWhite on chemistry for photoassisted deposition on functionalized self-assembled monolayers (SAMs). It's a possible route to area selective deposition. https://t.co/tBFXZgpKM0
RT @the_ScienceTalk: Balancing work and leisure activities is crucial! https://t.co/p4MmhQ2jUr
It's been a fun week of tweets by the @McElweeWhite group. We leave you with a reminder that depositing nanostructured materials doesn't always require exotic methods. Here is deposition of vertical nanoflakes of WS2 by chemical vapor deposition. https://t.co/32aZPB7atc
RT @the_ScienceTalk: Never be afraid to be yourself! https://t.co/W9ZXTFXhfZ
Thank you @McElweeWhite of @UFChemistry for a wonderful week of science, do give Lisa a follow!🥳 https://t.co/LjlMwQpB2g
George Mihailescu
"Perfect Broccoli with Quantum Thermometers (QuT)" 🥦🥦🥦🥦🥦🥦🥦🥦🥦🌡️🌡️🌡️🌡️🌡️🌡️🌡️🌡️🌡️ Please welcome @Georgio2313 of @cquest_ucd @UCD_physics for an exciting week of science 🥳🥳🥳 https://t.co/9kFtWhmPY1
RT @RealSci_Nano: "Perfect Broccoli with Quantum Thermometers (QuT)" 🥦🥦🥦🥦🥦🥦🥦🥦🥦🌡️🌡️🌡️🌡️🌡️🌡️🌡️🌡️🌡️ Please welcome @Georgio2313 of @cquest_uc…
For all you podcast consumers out there, here you go! 🥦🌡️🥦🌡️🥦🌡️ Monday's dose of science for you all 🎧🎧🎧 https://t.co/2Kd12mMGjy
1/17 It’s time for the new Twitter takeover! Hey everyone my name is George (@Georgio2313) your curator for the week, talking about all things Quantum! Today we’ll talk about how quantum and Ireland 🇨🇮 are connected. I’ll introduce myself and the groups in @ucddublin 🧵⤵️
2/17 I’m a PhD researcher part of the CATs and Nanoelectronics groups in UCD - your first example of the superposition principle! I’m looking at applications and ways of controlling nanoscale devices using tools from quantum information theory. More here: https://t.co/vunpDi6AiJ
3/17 I’m being funded by this really exciting startup company called Equal1 Laboratories (@Equal1L) which is based in Dublin 🌦️ and California 🌅.
4/17 With several generations of quantum processors, they are the first quantum company to successfully fabricate such devices using STANDARD and already COMMERCIAL CMOS (semiconductors predominantly used in everyday tech) technology! 💸
5/17 We’ll dive into Equal1 later this week, but you can check them out here in the meantime: https://t.co/6AFn3lZbPx
6/17 The CATs group 🙀 I’m part of is led by Dr. Steve Campbell (@quantumwizard) - an expert in quantum thermodynamics and information theory. Check us out: https://t.co/upXcbfXKkb
7/17 The expertise and research direction of the group is vast - from Quantum Darwinism (the emergence of the classical world from the quantum world 🤯) to Quantum Speed Limits 🛑 in Thermodynamic Processes (fast schemes costing minimal amount of energy, important #protech)
8/17 Fellow CATs🐈 include: Postdoc Dr. Anthony Kiely, an expert in the theory of controlling quantum systems - in particular the Shortcuts to Adiabaticity method (fast routes to the final slow, changes of the controlling system parameters). He also is an expert rock climber 🧗♂️.
9/17 Our senior and most wise PhD researcher, and Steve’s first student: The excellent Eoin O’Connor, who like me has looked at thermometery but also Quantum Speed Limits and the statistics of the work being done in quantum systems!
10/17 Finallly, our last CAT: Eoin Carolan (yes everybody in Ireland is called Eoin 😍) whose main research goal is to quantify the energetic cost of quantum computational processes - a critical task! When he’s not researching, he’s out fighting for physics 🥊.
11/17 The Nanoelectronics group I’m part of is led by Dr. Andrew K. Mitchell an expert in many-body physics and in particular, Kondo physics. Check us out: https://t.co/wRXyswk5a0
12/17 Again, the expertise and research of the group is vast, ranging from exploring the use of machine learning in many-body physics, to quantum transport in nanoelectronic devices and molecular electronics!
13/17 Fellow Nano include: Our most senior PhD researcher whose wrapping things up, Jonas Rigo. A true chameleon 🦎 his research has been diverse, from machine learning effective models for quantum systems all the way to looking at transport properties of nano structures!
14/17 And our most recent group member: Emmanuel Bogacz who will be looking at neuromorphic quantum computing - which physically implements neural networks 🧠 in brain inspired quantum hardware.
15/17 We are all part of @cquest_ucd The acronym stands for Centre for Quantum Engineering, Science, and Technology. Bringing together expertise from the School of Physics, Mathematics, Engineering, and Computer Science, all in the pursuit of expanding our quantum horizons!
16/17 CQUEST has over 25 permanent staff members and is lead by Dr. Andrew K. Mitchell, with funding from Science Foundation Ireland, Irish Research Council, and Disruptive Technologies Innovation Fund and industry ties to Equal1 Labs and IBM-Research! https://t.co/OOtUSYLaL6
17/17 We’ll see you later tonight guys for some more fun, for now I 🌊 goodbye 😊
1/8 Hello again to all!! 🙋 Quantum physics has deep historical roots in Ireland 🍀. Let’s explore this and why Ireland still has a large Quantum contingent 🧵⤵️ https://t.co/FH5Pag2FnM
2/8 Sir William Hamiltonian, born 1805 in Dublin, Ireland, laid down an important formalism for quantum mechanics through his formulation of Hamiltonian mechanics. This was a powerful new technique used for working with equations of motion.
3/8 He also discovered the non-commutative algebraic system known as quaternions: where he famously carved an equation on the Broom Bridge in Dublin. More can be found here : https://t.co/Aw9ijGPoAZ https://t.co/8pit93ItNx
4/8 Erwin Schrödinger of the famous “Schrödinger cat” 🐈⬛ born 1887 in Austria-Hungarian Vienna carried out his work in Ireland for 17 years, a controversial figure who explored a unified field theory whilst in the Emerald Isle. https://t.co/JswbQCcQVX
5/8 John Steward Bell born 1928 in Belfast, Northern Ireland wrote a famous paper “On the Einstein-Podolsky-Rosen paradox” where he derived the famous “Bell’s Theorem”. Original paper: https://t.co/FdZap6B9tp
6/8 This paved the way for the 2022 Nobel prize in physics award to Alain Aspect, John Clauser, and Anton Zeilinger propelling the area of quantum information and showed quantum mechanics cannot be replaced using a hidden variable theory. Learn more here: https://t.co/pf2WOLId4T
7/8 Now we have the next generation of world leading quantum physicists with groups in Belfast, Cork, and Dublin to name a few — alongside a strong industrial contingent & government investment 🥳
8/8 Join us today as we explore some of the fascinating work being carried out in Ireland in a little thing called “Tardigrade Tuesday” & learn more about a current experts path into the Quantum 🫢 (this paper has nothing to do with Ireland, but is fun: https://t.co/Lfe9DGouZ8)
1/24 Tonight we will be talking to Dr. Steve Campbell (@quantumwizard) who provides us with his journey to becoming a professor, alongside advice to undergraduates, PhD researchers, and Postdocs 🧵⤵️ https://t.co/ftQIY5vgER
2/24 Q: Why did you choose to do a PhD in the domain of quantum science? 🤔 https://t.co/LFnRGN9i3k
3/24 A: As an undergraduate student, any quantum related modules resonated the most with me. Competition for PhD positions was no where near as high in 2008 so I had some options, but I was most drawn to the quantum related ones.
4/24 cont’d: At that stage I didn’t know about quantum computers or quantum information, but there were two projects in particular that I found interesting. Unbeknownst to me however, they both offered the chance to work with Prof. Paternostro.
5/24 Q: What was your favourite part of doing a PhD? https://t.co/t6lGWYbpS9
6/24 A: I was very fortunate in that I collaborated with many people in my works — I really enjoyed that element. It offered the chance to not only learn from new perspectives but also to travel.
7/24 cont’d: My favourite thing however, was the feeling I had when I first published a paper. It was really exciting that something I worked on was now out there and ‘good enough’ for others to build on.
8/24 Q: What was your favourite part of doing a Postdoc? https://t.co/N1tw9ABYhB
9/24 A: Here I had the chance to really travel a lot and participate in many new cultures, living in Ireland, Japan, and Italy. This was also the time that I managed to develop myself the most as a researcher.
10/24 cont’d: By joining different groups I learned many new techniques and heard interesting schools of thought. I also had the chance to be more independent, working on two single author projects.
11/24 cont’d: That was particularly useful in improving my self confidence as an independent researcher. It was also the time I cultivated my most significant collaborators, with whom I still work with closely to date.
12/24 Q: What was the transition from PhD to Postdoc like? https://t.co/qGE97xbUIe
13/24 A: The first year was very tough! I was in a completely different research group, with a different work culture and working in an area I wasn’t too familiar with.
14/24 cont’d: The level of responsibility was also orders of magnitude different. As a Postdoc you have to be an autonomous researcher, contributing to the development of students, while also developing yourself and career.
15/24 Q: Tell us about your journey of Postdoc to Professor for those looking to make that next step! https://t.co/9uJqDIPg2u
16/24 See this thread: https://t.co/0oiXzDIrm6
17/24 Q: Can you give some advice to undergrad students looking to do research? https://t.co/o3lHBfGhWj
18/24 A: Make sure you find an area you are *passionate about*. Doing a PhD is a massive commitment, and is not immediately financially rewarding, so make sure you choose a topic you love.
19/24 cont’d: Also, to get accepted to a PhD program nowadays is significantly more challenging than it was in my day. Take every opportunity as an undergraduate student to be as competitive as possible.
20/24 Q: Could you give some advice to PhD students? https://t.co/3EvSuxHlJA
21/24 A: DO NOT WORRY ABOUT METRICS‼️ Do not place value on quantity (of papers) and metrics over quality and understanding.
22/24 Q: What are the biggest challenges as a Prof? https://t.co/aHksBtqHmk
23/24 A: The time constraints — you have a wider diversity of responsibilities, and therefore less time to dig into the weeds. This is compensated by working more closely with students and teaching undergrads.
24/24 That is a wrap from Steve, thank you so much for your time! Tomorrow we will dive into some of Steve’s works & discuss life as a Postdoc researcher! You can check out @quantumwizard’s work on the website https://t.co/upXcbfXKkb
1/9 Following our conversation with Dr. Steve Campbell (@quantumwizard) today we explore some of his research output below 🧵⤵️
2/9 We begin with work which has a special hold over Steve’s heart 💕, the first work of his PhD “Dissipative scheme to approach the boundary of two-quit entangled mixed states”
3/9 In this work, they study how dissipation (a typically deleterious process to the coherence of a quantum state) can be used to create “maximally entangled mixed states” https://t.co/QRdPxZFsbf
4/9 See full details in the paper below: https://t.co/TvtBYbCx0y
5/9 Through the close collaborations built as a Postdoctorate researcher, Steve has also contributed (with Dr. Sebastian Deffner) to the community with an entry level book 📖🧐 to the field of Quantum thermodynamics & Information https://t.co/MaHjaxnx3o
6/9 I’ve actually benefited from this text directly as a masters student! https://t.co/6Um0Vatn3D
7/9 Steve has also looked at alternative representations of how a quantum system interacts with its environment: The collisional model approach. https://t.co/dYHW8V6b2e
8/9 In this picture, the environment is pictured as a large, discrete set of smaller units (ancillas) which interacts (collides) with the quantum system one at a time (conveyer belt). Image ref: https://t.co/vWRnOufFRC https://t.co/XSASpX5ia7
9/9 For a comprehensive list of Steve’s work, which spans metrology (making precise measurements), Quantum Darwinism (emergence of the classical world from the Quantum, please see his Google Scholar (https://t.co/KGzCjO6ga2)! https://t.co/Bm1THueTGh
1/11 Interested in learning about some of the challenges and rewards of being a Postdoctorate researcher? Want to learn about some exciting research in the area of Quantum Optimal Control? We speak to Dr. Anthony Kiely 🧵⤵️ https://t.co/fvVv8VYqvw
2/11 Q: What is your favourite memory from your time as a PhD researcher? https://t.co/r5zoNthlsl
3/11 A: In 2014 an opportunity arose for me to attend a workshop in Japan. It was a tremendous experience, meeting new people and travelling to such a different country.
4/11 cont’d: Alain Aspect (current Nobel prize winner, awarded in 2022) was there and would perform card tricks for the PhD students, with quantum themes like teleportation and entanglement.
5/11 Q: What has been then been the most rewarding element as a Postdoc? https://t.co/XxWNintnaL
6/11 A: I’ve really enjoyed being a more central part of a research group. We have a really nice setup in UCD and group dynamic. I’ve most enjoyed having the chance to help develop and mentor PhD researchers in the group.
7/11 Q: What has been the biggest change PhD -> Postdoc? https://t.co/S0UfBzXln8
8/11 A: As a Postdoc you have more autonomy and can largely dictate the direction of your own work. You also have added responsibilities, like mentoring PhD students.
9/11 Q: Does being a Postdoc have any big challenges? https://t.co/ZkBKmTlREp
10/11 A: One challenge is that you have to be prepared to work in different groups and countries.
11/11 Thanks so much to Anthony for his time! Later on we will share what his favourite work to date has been, and I’ll share what I think has been his coolest work! 🙀🍍
What a wonderful day to be alive and enjoy some Physics! Today we will talk about some of the Dr. Anthony Kiely has produced in the Quantum sector 🧵⤵️ https://t.co/CJXEZYFeA5
1/9 In the review paper, “Shortcuts to adiabaticity: concepts, methods, and applications” Anthony (and collaborators) explore state of the art methods of controlling quantum systems. https://t.co/kBotF0CEIM
2/9 cont’d: The particular control method they consider, STA’s, are fast routes to the final results of slow changes of a system parameter. https://t.co/vUfiq035Tm
3/9 These control methods can be designed both numerically and analytically - depending on the conditions and systems explored.
4/9 STA’s are instrumental in preparing and driving internal and notional states in atomic, molecular, and solid-state physics.
5/9 I personally love this review paper as it gives a nice introduction explaining what STA’s are — to different methods, and applications in items such as spin and bosonic systems!
6/9 When Anthony isn’t busy designing methods of controlling quantum systems (which is a really important task in computational tasks, etc) he’s can also be found analysing the cost of implementing them! https://t.co/S0WiHbTNzc
7/9 In his paper (and collabs) “Energetic Cost of Quantum Control Protocols”, they examine just this! https://t.co/ntddKWwFvU
8/9 They look at well known control protocols and employ an energetic cost measure in several systems, finding a hierarchy of costs emerging depending on the duration of the protocol itself! https://t.co/3FV82cYlJl
9/9 Anthony has also looked at disordered quantum systems, some chaotic systems, and statistics of the work distribution! Check out his full research profile here: https://t.co/gpNOkWFmcS
Tomorrow we will speak closely to a PhD student working on the intersection of machine learning & quantum physics — let’s dive into some of the issues in Ireland if you’re a PhD researcher 😬🧵⤵️ https://t.co/iBsZGqluVT
This week there was a protest regarding PhD rights in Ireland https://t.co/1tJErgTGUa
But why protest exactly? (Information from the wonderful @PWO_Ireland)
PhD stipends are set at the poverty line 😘 Not even minimum wage! An average EU PhD researcher is paid €32,100 - the Nordic countries have their pay start at €50,000. In Ireland, some PhD researchers earn €16,000, the lucky ones earn €18,500 ! https://t.co/2dyZLU7GIQ
Ireland prides itself as a research hub & world leader; the backbone of this endeavour is based off the work of PhD researchers. Why doesn’t Ireland show love to the PhD researchers? https://t.co/EtkrgXPA0B
Is it because they work little hours? Is it because they don’t contribute enough to research and the university?
Well, no. PhD researchers often support professors by providing tutorials, grading assignments + test. They are also the workhorse of the research being carried out in universities. This is far more than a 9-5 job.
There are many issues and people who cover them better than I can, I’ll highlight the main issues with links to amazing threads.
There are other issues too, especially for non EU workers and women. There’s some really good threads here: https://t.co/cLkQwoZpMs https://t.co/O5on2gsMuM
And here: https://t.co/7naOaH9Ymx https://t.co/29DXYPIeO7
@SimonHarrisTD https://t.co/98BJr4cJ0V
1/33 Today we speak to Jonas Rigo, a final year PhD researcher in the nanoelectronics group, with expertise in machine learning methods and many body quantum physics :)
2/33 Q: why did you decide to do a PhD? https://t.co/0BZr0rwdVp
3/33 A: At the end of my undergraduate degree, although I both enjoyed myself and learned a lot of physics, I still felt there was so much within physics I wanted to learn about.
4/33 cont’d: So I felt that doing a Masters degree would help satisfy my curiosity and quench my thirst for physics knowledge. Again, at the end of my masters, I still felt there was so much to be explored and to be learned.
5/33 cont’d: So, this then naturally lead me to pursue a PhD, where research would grant me the opportunity to dig even deeper into the weeds. Coming to the end of my PhD now, I still feel that there is so much physics that I want to explore..
6/33 Q: Is doing a PhD what you expected?
7/33 A: In many ways it is how I imagined it would be. I was very fortunate, in the university of Innsbruck (where I did my undergraduate) there is a strong focus on research.
8/33 cont’d: Here undergraduate students were encouraged to attend seminars, colloquiums, and journal clubs. This was further amplified as a masters student.
#9/33 cont’d: These experiences helped inform me on how research was conducted, so I had fair idea of what doing a PhD would be like.
10/33 cont’d: One thing about research that I was very excited about was how collaborative it is, and how it allows one to interact with new people and ways of doing physics.
11/33 cont’d: Unfortunately , due to the pandemic, I didn’t have the opportunity to collaborate as much as I would’ve liked too with other researchers outside of my group.
12/33 Q: Coming from abroad, what’s one item that you liked about doing your PhD in Ireland?
13/33 A: One thing I noticed is that, both in Italy (where Jonas is from) and in Austria, the research groups are larger, with many postdoctoral and PhD researchers.
14/33 cont’d: In practice, because of group size, this means that the PhD researchers are often guided and trained by the postdoctoral researchers, rather than directly by the supervisor with whom one applied to research with in the first place.
15/33 cont’d: In this situation, your supervisor is more like your boss. To contrast this, in Ireland I’ve noticed that your supervisor is more like your peer, and directly a collaborator. This is very nice.
16/33 Q: How was it like settling here, and were there any challenges in doing a PhD here?
17/33 A: Having moved from Italy to Austria to pursue my undergraduate and masters, I’ve had some prior experience living abroad.
18/33 cont’d: Logistically speaking, I found moving to Ireland (as an EU citizen) was quite easy compared to Austria. This is because as a PhD researcher in Ireland, you’re technically not employed.
19/33 cont’d; This means that you don’t have to worry about sorting taxes out etc. However, this is also a huge downside..
20/33 cont’d: You basically don’t exist in the eyes of the state; for 4 years you don’t have any contribution toward a pension; you have to pay for really expensive health insurance; and you’re paid less than the EU min. wage.
21/33 cont’d: This is all technically allowed as you’re not an employee! This then ties in with other issues; in Ireland, it’s impossible to find a place to live.
22/33 cont’d: In reality, to find somewhere to live often requires you “know a guy”. Then when you finally find a place, the rent is untenable given how small the stipends are.
23/33 cont’d: This is a massive challenge.
24/33 Q: You’re a final year PhD researcher, how’s that like and do you have any general advice to other PhDs in training?
25/33 A: Final year is stressful — it’s putting together the largest block of study (in my case 10 years) you’ve done to date into context. It makes you revise all the choices you’ve made along the way.
26/33 cont’d: But, now is the time to assess if you want to change career or continue down the academic path.
27/33 cont’d: I’ve done many interviews, both in the industrial sector and the academic one to help inform my future career path. I have many friends working in R&D for companies.
28/33 cont’d: It’s made me realise that intellectual property has a lot of value nowadays & that, as researchers, we are perfectly positioned to enter this domain. Research is a mindset and skill.
29/33 cont’d: My biggest advice to people in their latter years of a PhD is to do many interviews. The more the better, as you not only improve in taking them, but it also teaches you to more critically contextualise everything you’ve done.
30/33 Q: To wrap up, what’s been your favourite work to date?
31/33 lA: I really enjoyed working on making the NRG differentiable. This is a process inspired from machine learning which we apply to the numerical renormalization group.
32/33 cont’d: This is a powerful many body computational technique. I’m most proud of this work because it randomly occurred to me that maybe it could be done, and we actually did it! https://t.co/PD8pIHgMf7
33/33 That’s a wrap! Thank you to Jonas for his time and insights, if you want to learn more about machine learning methods in many body quantum physics or quantum transport, check out his Google Scholar: https://t.co/azq96GuOXY
Well, that’s me signing off! It was a really fun week. I hope we were able to give you guys a flavour of a researchers perspective & some insights into the booming area of quantum science and technology! May the force be with you all ✌🏼 https://t.co/Fgo80k6dG8 https://t.co/qqF8xgkWUd
Thank you George for a wonderful week of science 🥳 Do give @Georgio2313 a follow! Sign up here if you want to take over this account - https://t.co/o0Mthn8kYV https://t.co/z03INfieNc
Julio Terra
"Nanoscience revolusionizing Green Chemistry?" Please welcome @_julioterra of @LPDC_EPFL for a smashing week of nanoscience full of sheep, lake view, little prince, life at @EPFL_en and a ton of uber cool science https://t.co/YmjbsBP380
RT @_julioterra: I had so much fun talking to @RealSci_Nano! Thank you so much for having me at the podcast and I’m super excited to take o…
Hi everyone! I’m Júlio and I’m taking over the @RealNano_Sci account this week =D To get started, I invite you to think about The Little Price and its relationship with his little planet (asteroid B-612). The planet is so tiny that he walks around it and feels its curvature. 1/5 https://t.co/vLftPizl9m
He is always in contact with everything in his planet and he sees all of it at all times. When he goes to the Earth, the story changes: he doesn’t feel the curvature or interact with every being on Earth. That’s just because the Earth is so much bigger than he is. 2/5
We spend our wholes lives in the Earth (at least most of us) and we never get to see all of it or interact with everybody who lives on it. 3/5
The Little Prince’s height in the same order of magnitude of the diameter of his planet, which is def no true for the Earth (see picture). This scale similarity (or difference) changes the way he perceives the world around him, and we can extrapolate this logic to molecules. 4/5 https://t.co/nMyK6DmdHC
When molecules are confined in tiny (nano) spaces, they can behave differently. They may be affected by the curves on the walls of the confining media, have enhanced interactions with the atoms on the walls and with other molecules in the same space. 4/5
Chemists now try to understand and utilize these effects for many applications. We published a review article last year at @GreenChem (w/ @MooresResearch) where you see nanoconfinement being used to make chemistry more sustainable through catalysis! https://t.co/MuWIvUjKLV… 5/5
As scientists we work in an English-dominated world. Science is built upon learning from each other and we need one common language to be connected with the scientific world but that may lead to challenges for ppl who do not have English as their first language (Eng+) 1/2
Jacky Deng @WheresJacky from @uOttawa interviewed Eng+ scientists and outlined some of the challenges they face, strategies they have employed to navigate them, and impactful experiences such as having supportive supervisors. 2/2 https://t.co/kQHjEEB92l
We can't talk about Green Chem without the 12 principles that were outlined by @JohnWarnerOrg and Paul Anastas in 1998. These are a guiding framework for us to implement Green Chem in our practice. Take a look at this flawless graphic by @compoundchem https://t.co/8DFgbhE0mT
It has been a pleasure to take over the account this week and interact with all of you! I leave you with this picture I took the other day at the @EPFL campus 🏔️ Thank you Pranoti @MySci_PK and the whole team for the platform 🧪💚 https://t.co/EH56B3LPKb
Huge thank you Julio for a wonderful week of science! Do give @_julioterra a follow!🥳🥳🥳 Do you want to take over this account and feature on #UnderTheMicroscope podcast? Get in touch here - https://t.co/XVul5MHO6u https://t.co/qFS2r2Lcdy
Jodie Bradby
"High pressures & diamonds" 💎💎💎 Please welcome the amazing @JodieBradby 🥳🥳🥳 https://t.co/UKfYR2OQz3
Hello folks! Great to be passed the keys to RealScientists Nano for a week. Follow to peak through the window into my world of diamonds, high pressure physics, Head of Department stuff, and my work-life juggle! - @JodieBradby https://t.co/2APqAuh1Vr
Let's kick off with a mystery! So several days ago I was went out to lunch in Canberra (where I live - more on this later). In walking back to the car a sparkle on the footpath caught my eye and I picked up an item of jewelry. It LOOKED like a diamond. https://t.co/WCqn8WkZXG
But how to test? It was Easter so I wasn't in the lab. I did a few tests on it at home - I looked at it with UV light - many diamonds glow - such as the ones here pictured in my ring. (I used a torch from a covid testing kit and I am not sharing the pic of the jewelry here.) https://t.co/lgGEWBbVHx
And YES my found item did glow like a diamond under UV light! https://t.co/rLtjSpBV43
(The big diamond pic here is hiding my found item in the photo!)
So I am back at uni and in my lab today. I told some of my students I thought I found a diamond and they were unconvinced... the surface of the object looked pretty dirty! https://t.co/gYXoDx7sQI
But when we turned on the laser to measure the Raman - sure enough it WAS a diamond! Look at that nice sharp peak at ~1330 cm-1! Perfect diamond! https://t.co/roxj5Ze9du
I'll hand it into the police tomorrow. Hopefully it finds it's way back to its owner. https://t.co/Gk3YQMJxJX
@cosmicpinot I ‘felt’ at the surface of the stone with a sharp needle and the fact it was unscratched suggested a very hard surface. 👍
I thought I would do a thread on my university @ourANU and my beautiful city Canberra!
Canberra is called the bush capital as it’s surrounded by mountains & bushland. It has the reputation of being boring/ full of politicians but that is not my experience at all. I mean look at these hot air balloons - the mumma was commissioned to celebrate Canberra’s birthday! 🤯 https://t.co/2EfdMs7x1s
I am lucky enough to be a Professor at the Research School of Physics @PhysicsANU at @OurANU. Here is a few pics of our awesome group at @materials_anu https://t.co/LRaEn0upWk https://t.co/4cGvb47KA2
The @ourANU campus is so beautiful - especially in Autumn. https://t.co/YMjfwl9gyw
Today a thread about my fav science thing - beamtimes! https://t.co/8znOw0jQMa
But lets first take a step back first. So I am a 'condensed matter physicist'. We make up the LARGEST group of physicists (about 1/3 of us work in this area). It's a big field b/c it underpins many of the technologies we use every day. https://t.co/WFs12FJ4rC
Never heard of it? Yep - definitely not one of the commonly known sub disciplines of physics (no-one on a TV show like the big bang theory would be a condensed matter physicist!) but its super cool and really overlooked by students IMHO..
Many students coming into physics want to study astrophysics or quantum.. but often they tell me they don't want to just do theory or analyze data... they want to work in the lab and do experiments.
Condensed matter physics can be theory or experimental-based (or both). I am experimental and honestly its a LOT of cool experiments, techniques, equipment and tackles lots of real-world problems.
In my work I use so many very cool bits of equipment from electron microscopes.. Scanning electron image of an indent in a 'brittle' semiconductor (Ge)! https://t.co/7CdEFa5npD
To atomic force microscopes.. A series of phase transformation areas on Si after etching.. https://t.co/mzZHLrLQzo
To Raman spectroscopy.. Me and our Raman system.. https://t.co/kzTebnuJUO
BUT most of all I love it when we go on a beamtime and use synchrotron x-rays to measure our crystals. https://t.co/NFP5Un7Ues
I usually go to the Advanced Photon Source near Chicago and use the high pressure beamline. (Unfortunately we cant do these experiments in Australia... yet!) https://t.co/cAJQQrrrVw
We need to write applications for time and its quite competitive. The experiments are run 24/7 and we usually only get 48 hrs of precious beamtime per trip. https://t.co/6e7wmHLAL1
Those 48 hrs need to be planned very well and we usually have a small team of 2-4 who travel over there. We have a Plan A, Plan B, Plan C etc.. My aim is to never waste a photon! https://t.co/JklKAaefrj
More later.. time for a coffee (beamtime also runs on coffee.. and chocolate.. can you see why I love it!). https://t.co/v5r0aaPgHY
Hello again! Back to it! One of the main reasons I love going to beamtimes is that I get to do just science and we collect so much data over that time. Plus we are working in a huge science facility with so many other clever peeps. Its a huge buzz. https://t.co/S0eg1XS29y
Here is a photo of me really in my happy place! I think we just ran a beautiful experiment on the high pressure phases of Si that worked really well. We sat here for about 8hrs straight and it felt like 30 mins. https://t.co/YFq2jqGNtn
We have lots of traditions associated with beamtimes that makes it fun... deep dish Chicago pizza, beamtime pancakes.. But its also the people. Here are a few of my fav peeps anxiously waiting for a result! https://t.co/iTkRSxcjpv
The set-ups we use are pretty mind-blowing. Here is a pic of our experiment in Feb of a high pressure cell with two diamonds getting pushed together by a inflating metal balloon. One of the diamonds is rotating to increase shear while we fire X-rays through the whole thing! https://t.co/pnGJZSWypN
The big thing that looks like a mirror is the detector. We record images (like an medical X-ray) of how the X-ray scatter off our sample which is under pressure/shear.
So hope you can see now why its so very cool! And why condensed matter physics is so underrated! I do feel that students might be more excited by the work if they knew this was a fairly common experience for us!
In VERY EXCITING news we are installing some new equipment in the lab this week. Its a new laser machining system that will be used to make tiny holes in gaskets of metal for our high pressure experiments. Here it is in the crate.. I'll post a pic of it unpacked soon! https://t.co/8JlIbX72KK
Been a big day - we got our new laser drill working. 💪🤓 https://t.co/8gEAMFoLBm
It makes tiny holes in little coins of metal that we use as sample chambers for our high pressure equipment. https://t.co/31m6el3kgk
We had fun playing with the custom shapes! (Writing ANU!) Excellent day - started playing at 10am and had it working by 4pm. ✅ https://t.co/4nPEyvNMCT
In other news my gorgeous doggo #MetroTheBordoodle learnt a new trick. 😂👍 https://t.co/5nBMlt2NhS
A sneaky few hours of tackling my email at ANU while waiting to pick up a kid this morning. View be worse.. https://t.co/ZxN0PYmw9x
A few jobs ticked off my list and stress levels drop.. one of the things I was doing this morning was on a Physics conference I am organising here in Canberra in Dec. Its a joint meeting between the @ausphysics and the Aust and NZ Optics Society. #SummerMeeting
It has been great fun to take over the account for a week! My last tweet is some diamond anvil cells - the fit into the palm of your hand but can create pressure higher than the centre of the Earth! A huge thank you to @MySci_PK and the team. 😍 Shine bright folks! 💎💜💎 https://t.co/EDiTClfHTU
aaaaand with that ,thank you Jodie for the wonderful ride of high pressure, diamonds and other coool stuff! Do give @JodieBradby a follow🥳🥳🥳💎💎💎 #UnderTheMicroscope @the_ScienceTalk @materials_anu Want to take over this account? Tell us here - https://t.co/tfo8YBVOx0 https://t.co/TC77ibq5ul
Steve Streets
🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑 "Nano hockey sticks to win over diseases" Please welcome @Street_Research for a wonderful week of science!🥳 @Mysci_PK @the_ScienceTalk @MannersResearch @UVicScience #UnderTheMicroscope https://t.co/vKGtw8vv4Q
Hey everyone! So great to be able to spend the week talking to you about all things #nanomedicine and #precisionmaterials. My name is Steve @Street_Research, and I am currently a postdoc in the @MannersResearch group at @UVic on Vancouver Island in Canada 🇨🇦 1/7
This week I’ll give you an insight into what life is like as a nanoscientist in Canada, and introduce you to my research on polymeric nanomaterials for therapeutic delivery. Today I just wanted to introduce myself and explain my career choices to date! 2/7
But first, where do I live? Victoria is a smallish city on Vancouver Island off the West Coast of Canada in British Columbia. We are a 4h ferry ride from Vancouver and Seattle. The first thing most people who live here will tell you is that it is beautiful! 😍 3/7 https://t.co/pyxY2qeW0y
If you like nature and the outdoors, this place is heaven! Victoria is 3h from a ski resort, and it has some of the most beautiful mountains, lakes, beaches and ancient forests. The island has everything from bears, wolves, cougars, and elk, to sea lions, orcas and whales! 4/7 https://t.co/KZEMLcXPLS
Victoria is a nice enough place to live. It has everything you need including some amazing breweries, vineyards and restaurants. There are loads of cool hikes to do, and lots of sports like open-water swimming, kayaking, cycling, climbing, surfing and fishing! 5/7 https://t.co/rK7bVncWa4
It does have its problems too though. Because of high demand, housing here is expensive – the average property price in Victoria is over $1,000,000! This means rent is also expensive here, reaching an average of $2000 for a 1-bed apartment. 6/7 https://t.co/4k0R1mNRht
Victoria really is a lovely place to live though. It is a popular tourist destination, and I highly recommend a visit if you get a chance! Later on I'll speak about my career choices and what I am getting up to today - stay tuned! 7/7 https://t.co/eI6DesFsgD
Hey again! It’s an interesting week to be doing a takeover... Today I attended a demonstration at UVic that was organized by @SupportOurSci. They organised a nationwide walk-out to advocate for living wages for grad students and postdocs in Canada. 1/4 https://t.co/Sn6fwfe6ji
Funding for science in Canada has not changed since 2003, so Canadian researchers have effectively received 20 years of real-term pay cuts (inflation over this time is ~50%!). 2/4 https://t.co/UzHC60yA6d
Pay ranges from $17,500 to $35,000 per year for masters students and PhD students. But remember rent is ~$2,000 per month in Victoria! Grad students are also expected to pay $8,000 in tuition fees per year, which further adds to their financial pressures. 3/4
The ‘Support our Science’ campaign aims to increase funding for science so that researchers are more fairly paid and no longer living below the poverty line! We had a pretty good turnout at UVic today. Let's hope things change! 4/4 https://t.co/aubVBYNLy8
Morning everyone! Today I wanted to tell you a bit more about myself and my career choices. Buckle up! I grew up in London, in the UK. I went to a comprehensive school, and was the first in my family to go to university. I was never sure what I wanted to do when I was older. 1/25 https://t.co/pjqaw3gcFb
Growing up, whenever I was faced with a decision about my future, I just chose what I enjoyed doing the most. This led me to study Maths, Chemistry, IT and history for my A-levels. 2/25
When it came to choosing what degree to study, I thought I wanted to study computer science. Maths was too abstract at that level, and history was more of an interest than a career choice. After some open days, I was put off of comp. sci, and enthused by chemistry instead. 3/25
However, all did not go to plan. I did poorly in my AS levels (the exams you take at 17 in the UK), getting C,C,D,E, with an E in AS chemistry! Shortly after I was also hit by a car and missed several months of school. 🚗🤕🩼 4/25
Faced with an uphill battle, my parents got me a tutor in maths and chemistry to help me catch up. I worked hard and managed to improve by a grade in every subject, getting B,B,D for my A-levels (I dropped history after AS). 5/25
Curiously, the chemistry tutor taught me for a couple of lessons before telling my parents that “I wasn’t learning anything and that I would never be any good at chemistry”. This probably marks the lowest point in my chemistry career. 6/25
My parents got me a new tutor, and I like to think I’ve proved the old one wrong on that front now 😅. Don’t let anyone tell you what you can and can’t do, because you can achieve ANYTHING if you set your mind on it. 7/25 https://t.co/CBmzXbMwTr
With a D in chemistry I didn’t get into my first choice university, but my backup choice was @UniofReading, who had space on their MChem Chemistry course and took a chance on me. I am very grateful to them as my life would be very different otherwise! 8/25
All of us who got a D had to go to special Saturday classes in our first year to catch up with everyone else. Ironically, those who went to these classes usually ended up getting better grades in their 1st year than those who didn’t! 9/25
I had a great time at Reading, and I made many friends for life. I managed to improve on my grades every year, whilst also working 12+h a week in a bar so that I could afford to live. I definitely struck the work/life balance perfectly, and had my fair share of nights out! 10/25 https://t.co/b6KGRYPiyv
At the end of my degree, 5 years after getting an E, I graduated with a first – the highest grade you can get in the UK. I was one of the top students on my course, and won an award for “the most improved chemistry student”! 🏆 11/25 https://t.co/j6YPXrOfzr
The award was sponsored by a contract-based analytical chemistry company. They offered me a job, and I worked there for almost a year, analyzing pesticide residues from agrochemical field trials. I learnt a lot while there, including how to work in a GLP lab. 12/25
However, the work didn’t challenge me enough, and my performance fluctuated. I decided that I wanted to go back to research and study for a PhD instead. I was lucky to get a place on the amazing @BCS_CDT at the University of Bristol. Here is the 2012 cohort! 13/25 https://t.co/reaNZJjNaJ
After a couple of months of travelling, I returned to academia and began my 3 rotations as part of my CDT training. My PhD was also some of the best times, and once again I made friends for life there. 14/25 https://t.co/rHsgPc6Nxr
I felt WAY out of my depth though – I felt like I had forgotten most of my chem degree, and definitely felt like an imposter for a while. The best advice I can give on this topic is just to ask questions, as nobody knows everything. 15/25 https://t.co/AFV8h0covq
Whilst there, I did several rotations, covering organometallic catalysis, supramolecular chemistry, and organic synthesis. A great thing about CDTs is that you can choose your PhD project and supervisor from a big list! 16/25
I opted to work for @MCGalan_Bristol on a really interesting collaborative project with @JuanCar77902465 that involved 4-stranded DNA structures called G-quadruplexes. More about this tomorrow! 17/25 https://t.co/6QtNGVaSXX
My PhD took me to all kinds of interesting places. I lived in Spain for 3 months working with my co-supervisor, I did a 3 month industry placement with my Industry supervisor at Novartis in Switzerland, and I won a JSPS fellowship to spend 3 months in Japan! 18/25 https://t.co/Q80MItVrea
During my PhD I became interested in chemistry outreach, and ended up covering for the director of outreach at Bristol for a few months after my PhD ended. I wanted to stay in research, but needed a job so applied for everything under the sun. 19/25 https://t.co/GHLl9rZ9gw
“If you throw enough stuff at the wall, eventually something will stick” was my motto. After my PhD I was interested in cancer research and CRISPR, and was lucky to get an EPSRC Doctoral Prize fellowship to work with Ian @MannersResearch. 20/25 https://t.co/OoPFCDvWk6
The fellowship was my last opportunity to stay in academia, as I had exhausted all other opportunities and needed a job. It had its intended effect of retaining EPSRC-funded PhD students, as otherwise I would almost certainly not be in academia today. 21/25
In 2018, Ian decided to move his group from the University of Bristol in the UK to the University of Victoria in Canada. I stayed on to help close down the Bristol group before moving to Victoria in 2019, just 3 months before the pandemic hit! 22/25
Originally, I planned to stay for a year or two before going back to the UK. The uncertainty of the pandemic meant that I was very happy to stay for longer in Victoria. It was a pretty good place to be during the pandemic with all that nature! 23/25
This leads me to today, where I am a senior postdoc in the group who helps to manage and coordinate our research activities. It’s a fun, varied job, though multitasking admin with my own research is definitely a challenge! 24/25 https://t.co/HCraa88Npg
That’s all for my story for now – I hope you’ve enjoyed it, and thanks for reading if you made it this far! Later on I'll show you UVic's campus, and tomorrow I’ll talk about my research in more detail. See you then! 25/25
Today in science, I attended a seminar by the excellent @LaurelSchafer from UBC. After, there was a poster session. Attending seminars is an important part of being a scientist - you get to see some great people present their research, and you might be inspired with new ideas! https://t.co/Z1Ep2x5x7O
Morning! So, where do I work? The University of Victoria is a medium sized university, situated on the traditional territory of the lək̓ʷəŋən first nation, about 20mins from downtown Victoria. I usually get the bus to work so I can read and be 🌿. 1/5 https://t.co/jIX5SdXwka
The campus is really beautiful, with its own botanical gardens, lots of trees, and deer (just don’t ask what happened to the bunnies…). We also have our share of totem poles, which are created by the first nations. It’s a nice campus to work on 😄 2/5 https://t.co/dpbyXNthPN
Whilst we have most of the equipment we need for research here, we don’t have everything! We work closely with the other universities in Vancouver, so some of my colleagues send samples to them and visit the mainland occasionally for research. 3/5
We also have to plan our experiments well in advance, as ‘Island time’ definitely extends to receiving chemicals and equipment! 🚚⛴️ Oh, and the less said about the food on campus, the better... 4/5 😅
Overall, UVic is a good place to work though. Later on I’ll speak some more about my research journey! 5/5
Evening! My research journey has been pretty varied. I never really knew which areas of chemistry appealed to me most. I was fascinated by building functional molecules and materials, using chemistry to create things which can do something useful. 1/30
For my masters project, I worked with Prof. Howard Colquhoun on developing polymer-supported 'molecular tweezers' for the detection of nitroaromatic explosives like TNT. It was a really interesting project, with a very important application! 2/30
Explosives like TNT go boom because they have a lot of high-energy nitrogen and oxygen atoms forced into a small space. When they detonate, they release N2 and O2 which is a strongly exothermic reaction. 3/30 https://t.co/SCV6xrncVZ
The molecular tweezers I was working with contained electron rich ‘prongs’ that bound to the electron-poor TNT. This changed the fluorescence of the tweezer, allowing us to ‘sense’ the amount of TNT present by how much they glowed! 4/30
We added the molecular tweezers to a polymer to change the material properties – we wanted to make flexible films instead of a hard solid! Unfortunately, the polymer sensors that I made were worse than the original design. I learnt lots though, including polymer synthesis! 5/30
In my CDT, I did 3 rotations in the Wass, Aggarwal and Davis labs in Bristol. In the @WassResearch lab, I was making new catalysts to upgrade ethanol into butanol – a more advanced biofuel. I learnt lots, especially about organometallic chemistry! 6/30 https://t.co/vXcsDcsBHK
In the @AggarwalLab, I got a taste of #organicchemistry and learnt how to use their Lithiation-Borylation methodology to make complex organic molecules. Some examples of the molecules they have assembled using this methodology are in this cool paper: 7/30 https://t.co/8d89Rdbajv
In the Davis lab, I dipped my toes into supramolecular chemistry, learning how to make and test synthetic anion carriers that can deliver chloride across a lipid membrane. These have potential as treatments for diseases like cystic fibrosis! 8/30 https://t.co/oDz3qdELLJ
By this time I knew that I was interested in building functional molecules and materials, and was increasingly interested in medicinal chemistry. I had considered med school in the past - I saw med chem as a way to combine my chem skills with my desire to help treat disease! 9/30
We had over 30 PhD projects to choose from. @MCGalan_Bristol had a really interesting project in collaboration with @JuanCar77902465, who was based at the CSIC in Seville, Spain at the time. The aim of the project was to develop sugar-based anti-cancer drugs! 10/30
But what is cancer? Well, in short it’s a collection of diseases that lead to uncontrolled growth of the bodies own cells. These mutant cells spread throughout your body, taking over vital functions and ultimately leading to death. 11/30 https://t.co/OND66ZdF3P
It’s hard to treat because you need to find a way of selectively killing the mutant cells, without also killing the healthy cells! BUT, the mutant cells used to be healthy, so there are few differences between them! 12/30
Cancer research is therefore all about finding these differences and making medications that selectively kill the cancer cells without also killing healthy cells. Common treatments include surgery, radiation, and chemotherapy. Chemotherapy is treating cancer with drugs! 13/30
But, many of the older chemotherapy agents like cisplatin are not selective for cancer cells – they kill all cells, so the aim is to kill the rapidly dividing cancer cells before you harm the patient. This is why chemotherapy often has bad side effects like hair loss. 14/30
The story of how the first chemotherapy drugs came about is really cool, and involves mustard gas, and a WW2 bombing! 15/30 https://t.co/qNqHpGWpii
Nitrogen mustard (aka mustard gas) was the first chemotherapeutic. It was developed into Cyclophosphamide, which remains a frontline chemotherapeutic today! 16/30
Luckily for us, we are entering a new age of ‘precision medicine’, with more specific treatments for cancer appearing all the time. Side note: The first targeted cancer treatment (and my fav drug) is called imatinib. It’s a really cool story! 17/30 https://t.co/330uv46rc7
The target of my research was a unique 4-stranded DNA structure called a ‘G-quadruplex’ (G4). G4s are very interesting structures, and we are still learning about them. They are involved in key genome functions, and have many links to cancer biology. 18/30 https://t.co/kSfQok0WUB
Many proteins involved in cancer have G4s in their genes. By stabilizing the G4, you can stop protein production and kill the cell. G4s also affect a key cancer enzyme called telomerase, which is responsible for immortality! 19/30 https://t.co/r6Ait7YBjv
To stabilize a G4, chemists have been designing and testing small molecules that can bind to G4s and prevent them from unfolding. As G4s are enriched in cancer-associated locations, they should be more specific for treating cancer than the older chemotherapy treatments. 20/30
We hoped that the sugars could be used to bind to G4s in a specific way. I developed some odd molecules with sugars, and showed that they had anti-cancer activity! I tested the anti-cancer activity myself, so I learnt cell culture at this time. 21/30 https://t.co/gk2TNTwmP8
As I had done all the hard work, I also decided to submit some cover artwork too. I was lucky to have my reimagination of the Beatles Abby Road album cover published! This is a street in Bristol, outside where I used to live. 22/30 https://t.co/oQLfNPYCwm
This project took most of my PhD, and was the only published paper from my main PhD project when I graduated. Since then, with lots of help from collaborators and coworkers, we have published a further two papers on G4s! 23/30 https://t.co/E9Pz1cn4HE
We also showed that they can have antiparasitic activity, for e.g. Leishmaniasis. We performed lots of ‘Structure-Activity Relationship’ (SAR) studies, which is varying the structure to see if it works better – a common task in med chem! 24/30 https://t.co/ssdoHsMEFY
However, the road to getting a drug into the clinic is expensive and fraught with failure – it takes years, and millions of $ to get a new drug through clinical trials, and for every 10,000 drug candidates evaluated, only 1 will make it. So the chance of success is slim! 25/30
We are still waiting for the first G4 targeting drug to be approved, though several are in clinical trials. It was because of this that when I finished my PhD, I was thinking about what some other promising cancer treatments might be. 26/32
I had become really interested in nucleic acid therapies like CRISPR, which is a promising gene therapy that won the Nobel prize in 2020. I had also become interested in cancer immunotherapy, as harnessing the bodies immune system seemed an elegant way to treat cancer! 27/32
I saw that DNA and RNA treatments were very powerful tools for treating disease, however they were both in the realms of biology – I struggled to see how I as a synthetic chemist could contribute to the area. 28/32
Then I learned that delivering nucleic acid therapies like CRISPR to their target location in the body was actually one of the biggest challenges that this technology faced. THIS was a problem for synthetic chemists! 29/32 https://t.co/o7bADaTIm8
I knew that polymers were widely studied for therapeutic delivery, and I knew that the Manners lab had been working on precision polymeric nanostructures, so I thought it might be interesting to see if you could use the precision nanostructures to deliver nucleic acids! 30/32
And so that was how I came to join the Manners lab, working on polymeric DNA delivery systems. My journey as a chemist had come full-circle, and after not knowing what areas of chemistry I liked for a long time, I had returned to functional polymers! 31/32
This is where we will leave the story for now – tune in tomorrow to find out the rest! Thanks for reading this far. Peace ✌️ 32/32
How do you image something that’s 1000x smaller than the width of a human hair? You use a microscope! Except we need to use electrons to see things this small (which costs 💵). This is our Transmission Electron Microscope, which I was using today to image some tiny sticks! 1/6 https://t.co/7PDqdbbm8r
In case you were wondering how small the samples are, this is the sample holder next to my finger. The tiny circles are where the sample goes – inside each is a mesh of 500x500 squares, which are each 0.03 mm in size. You can see one square on the screen in the first image! 2/6 https://t.co/0jKaGp25p3
This is an example of the images you get. This is actually a nanofiber sample that I imaged today! The white bits are the nanofibers (sticks), and we use Uranium to ‘stain’ the sample to get the dark background. And yep, getting your hands on Uranium is as hard as it sounds! 3/6 https://t.co/caJ1Rw6lL3
This is part of our lab space. We are quite lucky, as the lab was set up in 2017 so everything is max 5 years old! I even got to see what new clamp stands look like 🤯 (spoiler alert: they don't come rusty...) 4/6 https://t.co/7Z4f8DJvZx
And this is my fume hood. We use these to do chemical synthesis as the hood sucks all the bad things away (only chemicals, sorry 😅). Mine is quite clean at the moment as I’m not doing much synthesis at present. I also have lots of bench space for doing self-assembly. 5/6 https://t.co/DFAqvFp7T9
And finally, on the right is what a sample of nanofibers in water actually looks like! The sample on the left is after they have been degraded by enzymes. Whilst some nanofibers can be coloured, usually they are just transparent liquids - so not very exciting to the eye! 6/6 https://t.co/4BKhqdaMQ6
It’s time to learn about nanomedicine and nano-sticks! Let’s start with the 3 different classes of medicines. First, you have small molecule drugs, such as cisplatin or doxorubicin (both anti cancer drugs). This is the oldest class, which still pulls its weight to this day! 1/25 https://t.co/kCJinIWk5i
Small molecules typically have a biological ‘target’, which they bind to, to have their intended effect. Designing the ideal drug that works on its intended target without having off-target effects or issues with delivery around the body is a big challenge. 2/25
Next, you have what are called ‘biologics’, which is a fancy name for things which are derived from biology, such as proteins, hormones, and antibodies. These are usually much more complex mixtures, and typically larger in size than small molecules too. 3/25 https://t.co/U5siaTPBxI
Biologics might also have a biological target that they inhibit (like antibodies), or they might be therapeutics themselves (like insulin). 4/25
The third class is ‘nucleic acids’ (NAs). This includes both DNA and RNA therapeutics. Advances in science mean that this new kid on the block is rapidly growing and becoming a powerful method for treating disease. Examples include mRNA vaccines, and siRNA cancer therapies. 5/25 https://t.co/fQuWKxxyAN
A separate, but related area is gene therapy, which aims to cure genetic conditions like sickle cell anemia. One popular gene editing method is called CRISPR (it won the nobel prize in 2020). Both NAs and biologics can be gene therapies. 6/25 https://t.co/98nlQGh1I2
However, all of these classes of medicine suffer from the same problem: It is bloody hard to get them to their desired location inside specific cells in your body. A number of issues have to be overcome, at multiple different stages of the process. 7/25 https://t.co/HpaYjl1gqb
It’s kind of like trying to pull off the ultimate heist (Oceans 11?). You have many barriers to overcome, and you need to overcome them all otherwise you’ll fail. Evade casino security? Get down into the vault? Open the vault door? All challenges to be overcome! 8/25 https://t.co/fqal7Lno5W
Sometimes, small molecules and biologics can be designed in a smart way so that they don;t need any help – they have to have the perfect balance between activity and delivery effectiveness. But this is hard, and many small molecule drugs, biologics and NAs do need help. 9/25
The body is especially good at breaking down and recycling materials ♻️. This means we often need to protect the valuable therapeutic cargo from degradation. NAs are especially prone to degradation, which is an issue as they are so useful! 10/25
One solution to this problem is to use a delivery system for your therapeutic. Delivery systems play multiple roles – they are expected to protect the valuable cargo, whilst ensuring that it reaches its intended destination at the right time. 11/25
This is exactly like real life delivery companies! We hope our delivery systems are more like @Amazon, and less like Hermes/Evri! 🚚📦 There are many different delivery technologies, each with their own quirks. 12/25
The most popular are viruses like adeno-associated viruses (AAVs), and lipid nanoparticles (LNPs). Viruses are the most common delivery system used, as they evolved to do exactly this job! LNPs were used in the COVID RNA vaccines, and are the major rival system to viruses. 13/25 https://t.co/KWL2XkDbjE
Polymers are a third important type of delivery system, which is where my research comes in! Polymers and LNPs can both be used to deliver small molecules, NAs, and even biologics! One example of a LNP therapy is Myocet, which contains the anticancer drug Doxorubicin. 14/25 https://t.co/w3LWDQ37g8
There are MANY factors that affect how good a drug delivery system is. Some of the main ones are: particle size, shape, hardness, surface charge, surface chemistry, and architecture. Most delivery systems are nanoscopic, so they are very small! 15/25
How small you ask? Well, typically they are ~100nm, which is 1000x smaller than the width of a human hair. To put that another way, they are ~100x bigger than the speed your hair grows every second! At this scale, controlling the size and shape of objects is hard. 16/25
This size is too small to physically manipulate, though ‘top-down’ methods such as lithography are used to try and ‘cut’ nanoparticles out! (e.g. look up DeSimone’s PRINT). This size is also much bigger than the molecular world. For example, a glucose molecule is ~1nm wide! 17/25 https://t.co/RDigADTjKZ
So, we have to try ‘bottom-up’ processes, which aim to make larger structures from molecular building blocks. This is challenging as you have to rely on fundamental physics to get the building blocks to ‘self-assemble’ into the shape you want. 18/25
A sphere has the lowest volume out of any shape, so when these building blocks ‘self-assemble’, they usually form spheres to minimize their energy and avoid unwanted interactions. Making non-spherical nanomaterials is therefore a big challenge! 19/25
Both the AAV viruses and LNPs that are mentioned above are spherical or quasi-spherical. One of the aims of my research is to make non-spherical delivery systems to see if other shapes are better at delivering medicines! 20/25
But, there are limited methods for making non-spherical nanomaterials, and making them all the same size and shape is hard. This is important for medicine though! The study of using nanoparticles in medicine is called ‘nanomedicine’ 21/25
In 2007, the @MannersResearch and Winnick labs pioneered a method for making non-spherical nanoparticles, called ‘Crystallization-Driven Self-Assembly’ (CDSA). CDSA is (literally) driven by the crystallization of polymers. Crystals are rigid and prefer non-spherical shapes. 22/25
We can make sticks, called ‘nanofibers’, as well as ‘platelets’ which are flat, 2D structures. A whole bunch of other different particles have been made through CDSA too, and we are discovering more all the time! 23/25 https://t.co/rlb83nulMR
One promising aspect of this technology was that you can control the size of these unique shapes too. For example, you can choose the length of nanofibers, or the area of platelets. The resulting particles are all very similar in size, which is good! 24/25
What happens next? Find out later on in the epic conclusion to this tale! Happy Friday! 25/25
What is my research all about? Well, I want to turn these tiny sticks from a research curiosity into a useful material for society. I am especially interested in using them to treat diseases, because I think they will be really useful in this area. 1/20
At the start, these tiny sticks could only be made in organic solvents, and they were not degradable. This was a problem, as for nanomedicine applications we needed them to be biodegradable so they are non-toxic, as well as water soluble, as humans are mostly water! 2/20
By the time I started, the first examples of water-soluble and biodegradable nanofibers had just appeared in the literature. These works showed that it was possible to make nanofibers that could be useful for nanomedicine! 3/20
The first thing I worked on was helping to develop a new system with a biodegradable core that was stable in water. We showed they were non-toxic, which was a promising start! But, the polymer wasn’t functional – it couldn’t really do anything useful. 4/20 https://t.co/f0SNLhE5sy
So, I set about designing a new system that could do something. I thought things would be smoothest if I used ‘off the shelf’ components, so I combined several pre-existing technologies together to come up with nanofibers that I hoped would be able to bind and deliver DNA. 5/20
The first challenge was making and purifying the polymer. As any polymer chemist will tell you, purifying polymers is usually one of the biggest problems! Luckily I managed to overcome this issue. Next, I had to work out how to get it to self-assemble into nanofibers. 6/20
Luckily for me, the system that I made was able to undergo CDSA to form nanofibers really easily, which was great for me! I did have to screen lots of conditions to get it to work though. I also examined the degradation and toxicity of the nanofibers. 7/20 https://t.co/4h8XFoErxu
My next challenge was to work out how to get DNA to stick to them in a way which would let them deliver it to cells. This was hard, as you don’t want your fibers to stick together in a big mess (like below), and adding DNA makes this happen! 8/20 https://t.co/Eo7461OCjV
After lots of experiments and head scratching, I managed to find out how to get DNA to stick to the nanofibers in a way that would work with delivering the DNA to cells. My next challenge was to test them out! 9/20
This also proved to be a huge PITA, and I found out the hard way why DNA delivery was such a big challenge! It took many months and lots of experiments to iron out the details and get them working as DNA delivery systems. But, we got there! 10/20 https://t.co/JIQ8zbI439
And, we tested them out by delivering the gene for luciferase, the protein that makes fireflies glow in the dark! We delivered this to some brain cancer cells (pic of the unedited cells below). We knew our experiments worked as we made glow-in-the-dark brain cancer cells!😅11/20 https://t.co/l7LLSJuvba
I wanted to see how well our sticks compared to balls as well as normal polymers and lipid nanoparticles, so we tested these out too. It turned out that the sticks were the best delivery system that we studied! 12/20
I wanted to show that non-spherical nanomaterials were promising for DNA delivery, so I hope they receive more attention in the future. Since then, we have played with some more variables, and managed to improve their DNA delivery even further! 13/20 https://t.co/7xmlRb9XuY
But, that’s not all that these functional nanofibers could do. I worked with others in our group to see if they could kill bacteria. Our nanofibers were good at this due to their positive charge, which disrupts the negatively charged bacteria! 14/20 https://t.co/b5w4rLOYeY
I also worked with others in our group to develop a new design of nanofibers that could bind and hopefully deliver small molecules like drugs. This is an ongoing area of research, but the results were promising! 15/20 https://t.co/oIxjq6SwGK
Lastly, I also worked with others on making glow-in-the-dark nanofibers, which we hope might be used to detect diseases within the body. I got some cool data as part of this project, including some TEM images of nanofibers inside cancer cells! 16/20 https://t.co/lkD7HAjy3Z!
And in case you were wondering, this is what a cancer cell looks like via TEM. You can see all the things that you find in a textbook in here, as well as a load of other stuff I can't identify😅. Can you see the mitochondria? 17/20 https://t.co/HDaW6v0nPD
One of my highlights of this project was making cover artwork for @ChemicalScience. I wanted to go with a Star Wars theme, so recreated the opening scene of episode IV using nanofibers and some crudely drawn cancer cells! 18/20 https://t.co/mifDLYn68G
Whilst these were all promising results, there is a long way to go before nanofibers will be used to deliver the drugs or nucleic acid medicines of the future, be diagnostics or treat bacterial infections. This is what I, and many others are currently working towards! 😃19/20
I hope you enjoyed this thread on some of my research. Hopefully you found it interesting! If you have any questions about anything I’ve said this week, please ask away! 🤓20/20
Well, it's the weekend, so it's time for a break from science! I went for a hike in the forest - believe it or not, this epic old growth grove is a short drive from Victoria! 😊 https://t.co/43hzaBfjKM
And this will likely be my last tweet taking over the RealScientist Nano twitter account. I hope you've enjoyed the week's tweets, and there was something for everyone on here! If you have any questions or requests, let me know, and for more, follow me: @Street_Research !
I'll leave you with the sunset from my apartment in Victoria, which was truly epic today! Take care, and keep following your curiosity! 🤓😎 https://t.co/oMzSsWAlp3
@ChemicalScience Hmm... great question! 😅 I feel like he's maybe the nucleolus? Or maybe a cancer protein like telomerase?😁
🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒🏑🏒 Huge thank you @Street_Research for a smashing week of nanofibers and a sneak peek into your life in Victoria, Canada😍 Everyone, go give Steve a follow! @MannersResearch @UVicScience @the_ScienceTalk https://t.co/qAHQpHuyMU
Aine Coogan
🥤👩🔬🥤👩🔬🥤👩🔬🥤👩🔬🥤👩🔬🥤👩🔬🥤👩🔬🥤👩🔬🥤👩🔬🥤 "Purifying the Future: Layers of Potential with 2D Materials" Welcome @AineCooganNano of @gunkogrouptcd @TCD_Chemistry for an uber cool week (or two)🥳 👇@mysci_pk and Aine conversation only on @the_ScienceTalk https://t.co/DiHRVB7vea
RT @AineCooganNano: Veerrrry excited to have been invited on the Under The Microscope podcast with @RealSci_Nano and @MySci_PK 🎉🎉 Have a l…
Happy Monday everyone! I'm Áine (@AineCooganNano), a materials chemistry PhD researcher from @TCD_Chemistry and I'll be taking over this account for the next two weeks 🎉
As my first post on this account, I would like to express my sadness regarding the passing of John B. Goodenough. A phenomenal materials scientist, whose invention - the Lithium ion battery - changed all of our lives. Many condolences to his loved ones, may he rest in peace. https://t.co/p1NIfZrej1
Time for introductions! My name's Áine, I'm 25 years old, my pronouns are she/her, and I'm a final year Materials Chemistry PhD Candidate in @tcddublin 😊 I'm a 1st gen college student, from the tiny village of Dunderry in County Meath, Ireland 🇮🇪
@AyushSharma__07 @tcddublin Amazing, another first gen! Hope your research is going well 😊
I did my undergrad in @npcamtcd ⚛️ The nanoscience degree program was an equal mix of physics and chemistry, with an extra focus on materials science 🔬 In our final year, we undertook a research project which I did in @gunkogrouptcd and set me on the path to doing a PhD!
@npcamtcd @gunkogrouptcd Prof. Yurii Gun'ko's research group based in @TCD_Chemistry focuses on the synthesis and characterization of functional nanomaterials in a variety of areas - including MRI contrast agents, nanofiltration, chirality, solar cells and catalysis! https://t.co/4zYpobdfqD
RT @RoySocChem: While the chemical sciences community are mourning the loss of @NobelPrize laureate #JohnBGoodenough, it's an important mom…
This evening I'm going to highlight some of the areas of research from the Gun'ko group, and how my work ties into some of those themes! First up is chiral nanomaterials 🧬🔬
First of all, what is chirality 🤔 Consider your left hand and your right hand. They look very similar, right? If you place your left hand on a mirror, and you compare the left hand reflection in the mirror to your right hand, you'll notice they look identical! But are they..? https://t.co/mhPx5jc3LA
The short answer is - no🤯 If you try to place your left hand directly on top of your right hand, you'll find that they don't match up perfectly - they are perfect mirror images of each other. This concept of mirror image symmetry is the key to understanding chirality 🔑 https://t.co/whptw6WcW7
In chemistry, chirality refers to the property of certain molecules that have mirror-image forms, just like your hands 👐 Just as your left and right hands cannot be superimposed on each other, chiral molecules cannot be superimposed on their mirror images ❌ https://t.co/kqVTE7Gnuy
Chiral molecules have two forms, usually called enantiomers, which are kind of like left-handed and right-handed versions of the same molecule. They have the same chemical formula, and the atoms are connected in the same way, but their arrangement in space is different 🧬 https://t.co/FBNKZs2fbC
Our cells are mostly composed of chiral molecules, and they are very sensitive to chiral environments. So for example, when designing a new drug, we have to consider it's chirality - one enantiomer can be beneficial, while the other can be toxic☠️ https://t.co/aS8dG7djkb
Knowing this, your next question may be - why chiral nanomaterials? 🤔 This question will be answered tomorrow - for now I'm logging off to have my dinner and head to bed! 😴 Check back in tomorrow to hear about the fascinating world of chiral nanomaterials! 🧬🔬
Welcome to Day 2! We're back to discuss chiral nanomaterials 🔬🧬 Posting will be a bit sporadic today as I'm getting trained on some new equipment (!!!), but I'll try my best! Let's get this show on the road, and pick up where we left off - why chiral nanomaterials? 🤔
Combining the property of chirality with the already unique properties of nanomaterials, including quantum confinement, high surface to volume ratio, makes for some very cool science!
This review from @gunkogrouptcd alumnus Dr. Finn Purcell-Milton (@Finn_pm), lecturer at @WeAreTUDublin sums it up more eloquently than I ever could! https://t.co/ak3AJunTqo
@gunkogrouptcd @Finn_pm @WeAreTUDublin My PI, Prof. Yurii Gun'ko, is one of the pioneers of the field, dating back to 2007 with the preparation of chiral luminescent quantum dots 🔆🧬 https://t.co/6v3V6GqYdl
@gunkogrouptcd @Finn_pm @WeAreTUDublin The field has been advancing ever since, with potential applications in biosensing, chiral photonics, asymmetric catalysis and chiral separation! Chiral 2D nanostructures are of particular interest here 👐 https://t.co/59nlACDEBG
@gunkogrouptcd @Finn_pm @WeAreTUDublin So - where does my research fit in?🤔 As a side project during my PhD, I discovered we could make chiral 2D metal oxides, using very simple green, inexpensive methods 💲♻️ So - how did we do it?
@gunkogrouptcd @Finn_pm @WeAreTUDublin By stirring layered double hydroxides (LDH) in water with some base (NaOH) and an amino acid (phenylalanine), we found that the LDH can decompose into a chiral oxide, as the chiral molecule attaches to the surface 🧬 https://t.co/2N4I9fyCPw
@gunkogrouptcd @Finn_pm @WeAreTUDublin These chiral 2D nanosheet assemblies can interact incredibly strongly with circularly polarised light, which we hope can be utilised in the future for chiral/asymmetric catalysis, as well as biosensing! https://t.co/ldoWVtPm21
After all that mind boggling talk about chirality - something a bit more light hearted for ye this evening! You might all love nanoscience, but do you love it as much as me and @SimonianTigran love nanoscience (and Guinness)?🤔 Logging off for today, see you tomorrow for Day 3! https://t.co/ODJWsNlZDC
Good afternoon folks, it's Day 3 of my Twitter takeover 🎉 Today I'm going to focus on a major aspect of my work - tailoring 2D materials for use in water purification 🚰♻️
Global access to clean water is a huge problem, and is a consequence of increasing industrialisation, climate change, as well as escalating levels of inequality https://t.co/2ZfYpD5Naa
In 2015, the UN announced their Sustainable Development Goals (SDGs), with the aim of creating a "shared blueprint for peace and prosperity for people and the planet, now and into the future" https://t.co/fhZhZLSCNB
SDG 6 deals with water access and sanitation, and one of its goals is access to clean water FOR ALL by 2030. For that goal to be achievable, we need more research and innovation in new, cheap methods of water purification, which is where nanofiltration comes into play ♻️ https://t.co/5iLHwuqILR
Nanofiltration (NF) membranes are kind of like tiny sieves, which let only some of the smallest of molecules (typically < 3 nm) through @gunkogrouptcd alumna @Nat95gd kicked off the group's work on NF, and explains it in this review wonderfully! https://t.co/0klE27QXHO
@gunkogrouptcd @Nat95gd Our group focuses on NF membranes made of 2D materials, which look kind of like tiny, irregular sheets of paper. We can tell they are sheets using a scanning electron microscope (SEM), which shines electrons on a sample instead of light, to see smaller features! 🔬 https://t.co/fqItjAKkus
@gunkogrouptcd @Nat95gd When these sheets are stacked on top of each other, like in a NF membrane, they form hundreds and thousands of channels called pores that the water has to make its way through, and contaminants can get trapped in these pores, making the water cleaner! https://t.co/Q8Zku7hIjY
@gunkogrouptcd Early work in the group by @Nat95gd made new NF membranes from boron nitride - a cheap layered material, that can be exfoliated into individual nanosheets! These NF membranes could remove up to 100% of a variety of polluting dyes from water ♻️💧 https://t.co/IXssjjK2GE
Further work on this found that we could slightly change the chemical makeup of the boron nitride, introducing oxygen and hydrogen to make it more reactive🧪 It still performs just as well as normal boron nitride for water purification!💧♻️ https://t.co/FUqdpgaUxz
This work is so important because boron nitride is famously unreactive❌ If we make it reactive, then we can attach other molecules to the nanosheet surface. This could lead to specialised and targeted applications such as selective separation!
So then the question is - if these membranes are so good, then why are still working to improve them?📈 What are the drawbacks of these membranes? 🤔 My bed is calling, so the answer will have to wait until tomorrow! 😴😴 See you then for Day 4 and more nanofiltration! 😊 https://t.co/Pp70gGQrXx
Good morning folks! Happy Thursday and welcome to Day 4 of this takeover🎉 Throughout the day, I'll be chatting about why catalysis and nanofiltration can work together to move towards cheaper, more sustainable water purification methods!
Yesterday, we left off with boron nitride NF membranes - why did we feel the need to improve them? The problem was, when testing for dye retention, we could only use them once, before we saw a reduction in performance. The dyes eventually blocked the membrane pores ❌
These membranes are pretty cheap to produce (around €3 per membrane, only factoring in starting materials and using our setup) But, if you can only use the membranes once, then it turns out it's actually not a very cheap or efficient method of water purification 💔
We needed to come up with some way of stopping the membranes becoming blocked, or a way to remove the contaminants after filtration so the membranes could be reused This is where my layered double hydroxides can come in handy💡 https://t.co/L2J78UAsPa
Apologies everyone for the radio silence the past few days😅 Been busy prepping for #MC16 - the International Conference on Materials Chemistry run by @RoySocChem, which starts tomorrow in Dublin @ucddublin 🎉
Very excited to be giving a talk on Wednesday afternoon in the 'Materials for Life' symposium on our new photocatalytically active nanofiltration membranes, recently published in @JMaterChem A! #MC16 https://t.co/rmuEPSBiQI
Happy #MC16 Day 1! @RoySocChem The conference is split into 4 broad themes, first up for me today is Materials for Energy! A great talk in the afternoon session from Anna Ciotti from @CCEM_Group 🎉👏 @TCD_Chemistry https://t.co/HI2HU3eKCA
Presentation no. 1 ✅ Thanks to everyone for coming and having chats about my poster on chiral copper oxide! Looking forward to the rest of the conference and my talk on Wednesday 🎉 #mc16 https://t.co/cH53hgWfi4
@goldclusters Quite a new discovery but it can indeed be achieved! Our approach is through decomposition of CuAl layered double hydroxides using a chiral ligand (phenylalanine) and a base (NaOH) Feel free to read more about this work here⬇️⬇️ https://t.co/ldoWVtPm21
RT @AineCooganNano: Poster session out of the way, next up is my talk on Wednesday! Thanks for all the chats about chiral copper oxide, lo…
RT @gunkogrouptcd: Well done to @AineCooganNano on her poster presentation this evening at #mc16 ! Check out the Materials for Life sessio…
Happy Day 2 of #mc16! Back in materials for energy this morning - a particular highlight was a fantastic talk from @Kavanagh_Sean_ on modelling disorder in ABX2 materials for solar cell applications! Exciting stuff 👏 @lonepair @scanlond81 https://t.co/OdYcRIvluI
That's a wrap for Day 3 of #mc16! It was my turn to present today - thanks to everyone who popped into the materials for life session on a discussion on moving towards recyclable nanofiltration membranes ♻️ https://t.co/aU9JeTDY3y
RT @AineCooganNano: Talk done ✅ Thanks to everyone for popping into the session to hear about my research on working towards recyclable n…
Day 4 (final day💔) of #mc16 Got to catch some amazing talks in the Materials for Life session this morning from @giordanisilvia on Carbon Nano-Onions, and Clara Zehe from @QuinnGroupUCD on luminescent carbon dots! 👏
RT @GoringPD: @JACS_Au EAB member @RSessoli closing out #MC16 in style by telling us about magnetic molecules in quantum nanoscience https:…
Today is my final day curating this account 💔 today I'd like to chat a little bit more about our nanofiltration membranes, and follow it up by chatting a little about the lacking research landscape currently in Ireland...
I mentioned last week that we needed to think of a way to make our nanofiltration membranes reusable - our innovative solution to this was to add a photocatalyst into pre-existing partially oxidised boron nitride membranes 💡 https://t.co/l6ocq1KFuC
Photocatalysis is a light-powered chemistry process, which harnesses light energy to trigger a catalyst💡 It has many applications including helping break down pollutants and generating clean energy! ♻️
We found a suitable 2D material catalyst - copper aluminium layered double hydroxides - to put into the membranes This was important because boron nitride is a 2D material, so we wanted a material that wouldn't disrupt the structure and performance of the membranes!
As it turns out - this worked pretty effectively! We found that by using a €10 LED from the middle aisle of Lidl as our light source, that we could very effectively degrade a number of dyes which are very persistent pollutants in areas with high textile production ☠️ https://t.co/jpqJ7czLxk
These membranes perform almost identically to pre-existing BNOx-based membranes, with the additional functionality of being able to degrade the dues after the dye retention! This allows us to regenerate our nanocomposite for re-use ♻️ https://t.co/qa2b6wHMhb
We were delighted to get this work published #openaccess in @JMaterChem A! Couldn't have done it without support from various funding agencies - @IrishResearch PG scholarship, as well as @scienceirel @biOrbic_centre 🎉 https://t.co/rmuEPSBiQI
While I am incredibly lucky to have the opportunity to conduct this research and share it with people, it's important to note that the Irish research landscape is currently in turmoil - lack of funding, lack of infrastructure, as well as major exploitation of PhD researchers.
The top PhD stipend in Ireland is €18,500, which is 22% below minimum wage (source: @PWO_Ireland) For reference, that's about €1540 per month. The average rent in Dublin is currently standing €2324 per month. It is impossible for most to live here under these conditions. https://t.co/TyF2Lh9Thn
There are many other major problems facing PhD researchers in Ireland. We have zero employee rights, no sick leave, no maternity/paternity leave, and a plethora of issues facing international students regarding visa status and residency issues.
A recent review of PhD supports by the Department of Higher Education recommended a raise in stipend to €25,000, which is a good first step, but the rest of the report failed to recognise or address other key issues facing PhD researchers in Ireland.
In addition, this stipend increase will only apply to those funded by our government bodies - Science Foundation Ireland and the Irish Research Council. It seems based on this report that everyone else will get left behind and continue to survive on less than minimum wage.
The entire research system in Ireland is increasingly under threat due to chronic underfunding. The EU target is that member states should invest 3% of GDP in research and innovation. The average is sitting at 2.3% as of 2020. In Ireland, only 1.2% is invested. https://t.co/EYJVmIlWoa
Our research equipment is incredibly outdated and increasingly breaking down. Dr. Catherine Day from University College Cork revealed that 52% of equipment at Irish universities is over 10 years old, with 30% being at least 15 years old. https://t.co/7FltFexC2K
This is just one of the many consequences of chronic underfunding in the Irish research system. I have personally faced so many hurdles to my PhD research from old equipment breaking down because the department can't afford to service and maintain it.
We recently saw what sufficient funding can do for excelling research. @tcddublin recently jumped from 98th to 81st in the QS world university rankings. This was a result of a significant increase in the 'citations per faculty' metric. https://t.co/8yR7hbCdpW
@tcddublin As explained by @LindaDoyle and @TCDdeanresearch Prof. Sinéad Ryan, this is a direct result of a short-term boost in research investment. It is proof that this chronic underfunding of research in this country cannot continue if we want to compete on the global stage.
And on that note - that's a wrap from me! Thanks so much to everyone who followed and engaged with me over the past 2 weeks. If you want to keep in touch with me and stay up to date with what I'm up to, be sure to follow me over at @AineCooganNano 😊 Áine, over and out 👋
Huge thank you to Aine for wonderful 2 weeks of science and taking us through #mc16 conference. Give @AineCooganNano a follow! 🥳 Want to take over this account for a week? Sign up - https://t.co/YAeYjkYisc @irishresearch @gunkogrouptcd @tcddublin @DDUH12 @the_ScienceTalk https://t.co/PUYV0cxzhC
Ipek Efe
🦸♀️🦹♀️🦸♂️🦹♂️🦹🦸Superpowers of Ferroelectrics 🦸♀️🦹♀️🦸♂️🦹♂️🦹🦸 Please welcome @ipekkefee for week of ELECTRIFYING science! @ETH_en @ETH_Materials @the_ScienceTalk Check out episode 205 of #UnderTheMicroscope, Ipek's conversation with @mysci_pk 👇https://t.co/xzLfCoBAKE
Happy Tuesday everyone! My name is Ipek Efe and this week I am gonna take over this account🤩
First, a brief science-career introduction. I am a materials science Ph.D. student at @ETH_Materials @ETH_en. Previously, I did my undergrad in Turkey at @sabanciu, where I worked on the synthesis and microscopic analysis of glow-in-the-dark ceramic phosphor compounds🌟🌟
During my undergrad, thanks to the @EUErasmusPlus funding I had the opportunity to do several summer research internships. Worked on small projects on atom probe tomography @UniFAU, thermoelectric body heat sensors @icmabCSIC, and multiferroic BiFeO3 @CERN as a summer student. 🤩
My research internship on BiFeO3 made me very curious about ferroelectric/multiferroic materials. Later, I started my MSc. in materials science at @ETH_en @ETH_Materials and decided to focus on ferroelectric materials research in my master's degree.⚡️⚡️
As I only got more into ferroelectrics during my MSc (😄), I decided to do a PhD focusing on them. Currently, I am working at the Laboratory for Multifunctional Ferroic Materials with @MTrassin and @manfred_fiebig, to develop ferroelectric thin films with novel functionalities.🔬
During this week I will be tweeting about why ferroelectrics are very cool, what I am trying to develop during my Ph.D. and what other research topics is my group interested in, how does a day of a life of a Ph.D. student look like, and many more! 🌟🥳
Looking forward to interacting and chatting with y'all! Feel free to reach out to me through DMs and comments to ask specific questions 🤓
Good morning everybody!🌞Hope everyone is ready to get energized by ferroelectrics! ⚡️⚡️ First, I am attaching a previous video I made to briefly introduce ferroelectrics and why they can be important👇 https://t.co/d8d8QOXp4r
First things first: what are ferroelectrics? 📔Textbook definition: Ferroelectrics are materials with spontaneous switchable electric polarization. Too complicated? No, actually it's not! 👇
Imagine the magnets (that we also have on our fridges). 🧲They have a magnetic field within them naturally, with two magnetic poles N(orth) and S(outh) indicating the direction of the magnetic field.
Ferroelectrics are also similar, they have two poles. But this time the poles are not magnetic; instead, they consist of separated electric charges with opposite signs: positive and negative. https://t.co/MMkWFGjXJL
These separated opposite charges create an electric field inside the material, which is called electric polarization (P). For a polar material to be ferroelectric, the direction of the polarization needs to be switchable. ⚡️⚡️
🤨: Cool! But how do we switch/control ferroelectrics?? In many ways! That's what makes them amazing! The main ways can be listed as: 1⃣By applying an electric field ⚡️ 2⃣Using mechanical force 🔨 / sound wawes 🔊 3⃣Heating up / cooling down 🌡️🔥❄️ 4⃣Shining light on them 💡
What does this exactly mean? 🧐 It means that we can convert all of these different energy resources into electrical signals. Having an electrical signal means that we can put them in our electronics or we can make devices from them. 🤩
Indeed! Actually, we already have ferroelectrics in many devices around us: - Acoustic sensors, electromechanical sensors/transducers, imaging sensors, microphones - Infrared/UV detectors - Memory devices - Capacitors - Energy harvesters 📱💿🎙️📻🔌
HUGE thank you Ipek for an electrifying week of ferroelectrics!⚡️⚡️⚡️⚡️ Do give @ipekkefee a follow!🥳 Do YOU want to take over the account? Let us know here - https://t.co/9LqkKeoz22 @ETH_en @ETH_Materials @the_ScienceTalk https://t.co/4wcKLIX9bu
Levi Tegg
🔬🔬🔬Nano to Micro to Macro🔬🔬🔬 Please welcome @ljtegg of @Sydney_Uni for a week of microscopes microscope and some more microscopes!🥳 Check out Levi in conversation with @mysci_pk 👇 @the_ScienceTalk #UnderTheMicroscope https://t.co/VBwq0GLy55
Hello world! This is Levi Tegg (@ljtegg) and I will be your guide this week for all things materials and microscopes 🔬. https://t.co/Ccot0mI86m
@ljtegg I’m a postdoctoral research associate at @Sydney_Uni. I work for @JulieCairney of @Eng_IT_Sydney. This is the Madsen Building where our centre is based: https://t.co/LuaZdan8wg
Broadly, I use microscopes and other tools to characterise the structure of various materials. This week you’ll get (1) an overview of different types of microscopes and materials characterisation techniques…
… (2) what we can learn using microscopes, and why it’s important, and …
… (3) some very pretty pictures!
There are many types of microscope (as you'll see this week!) but the most widely known type is the light microscope (from https://t.co/2iXIi1ZrZE) https://t.co/RoQy6mgasK
Light from a lamp or laser is pointed at the specimen. This light is reflected, absorbed, transmitted, or scattered (RATS 🐀) by the sample. A set of lenses collect this light and direct it to a camera or eyepieces.
Light microscopes have been around for ≈400 years 😮. Here's a sketch of a louse and a Grey Drone Fly from Micrographia by Robert Hooke, 1665 (https://t.co/581VW1b0rH). Most microscope photographs ("micrographs") you've seen are probably from a light microscope. https://t.co/5uZSkY6cCh
Light microscopy is particularly impactful in the life sciences. Or so I'm told. I'm a physicist so I don't have any of my own biological microscopy images. So here are some entries into the @LightMicroAus 2022 micrograph competition (see https://t.co/ZLrp3iqG9C) https://t.co/ljIqb1Rp1a
Light microscopes are also valuable in studying materials - this includes alloys, ceramics, polymers, and much more. My research is in materials science, so that will be the focus of my Tweets this week.
This micrograph (also my Twitter profile header) shows a polished copper-manganese alloy, with dark crosses of manganese oxide and light crosses of manganese-enriched alloy. These features are bad for the application of this alloy, but make for pretty pictures. https://t.co/eqSpfSpQRn
That's a common theme in my work: using microscopes to see what has gone wrong. We'll revisit this theme throughout the week.
My main weapons are electron microscopes. Here's a scanning electron microscope (SEM) from our labs. An unassuming little white box, but a powerful machine 🧵 https://t.co/i5tJoEsSVr
SEMs scan a focused beam of electrons across a sample, and produce images of the surface. They're capable of amazing things. They can handle many different types of samples...
For example, here is the face of a moth (from https://t.co/qmg7CtHW8p). Microscale features are resolved in incredible detail. https://t.co/yvvJKmadRt
And here is a scale from a butterfly wing (also https://t.co/qmg7CtHW8p). https://t.co/mNdPcLIhIg
The SEM is also very useful in materials science (aka my domain). Here are some sodium tungsten bronze nanocubes aka jersey caramels (see https://t.co/UiJlLASbfh) https://t.co/tdUwkbvuSs
Here is a needle-shaped specimen of a highly-alloyed steel. Various types of carbides are visible. This specimen was prepared for atom probe tomography, which you'll see later in the week (see https://t.co/yJhZMEyWLs) https://t.co/Y62a4QXmTH
My research focus recently has been in nanoporous metals as a way to hold water ice for other microscopy. At the nanoscale they're very beautiful... https://t.co/k7Y8U26Js3
... even these very undesirable cracks make for dramatic images. That's what my career has been all about: taking pretty micrographs of failed samples. https://t.co/vGjlQkT1qG
Here's a transmission electron microscope (TEM) from our labs. Big and mighty in both stature and function! https://t.co/TI07MAX9qA
The SEM (see yesterday) usually looks at the surface of the sample. The TEM looks through the material. It's basically the same as a light microscope (Monday) but it uses electrons instead. (from https://t.co/5Ev7kPjG7K) https://t.co/m1g6XZglqF
We've had electron microscopes since the 1930s. Here's the first electron micrograph of a biological object from 1936. (from https://t.co/C7NQEWOdp7) https://t.co/W8fKjaH85z
As you might expect, microscope technology has improved a lot in the last 90 years! Today the TEM is used to image all sorts of samples at all sorts of magnifications. The key requirement is the sample be very thin, ideally < 100 nm ...
... if you can make a sample this thin, the TEM is a very powerful instrument. Here are some examples:
A very thin sheet of nanoporous gold - a different view of a nanoporous metal from what I showed yesterday (from https://t.co/aV3QblGANa) https://t.co/mbU7vXHjXj
Cryogenic TEM (cryo-TEM) of the very popular SARS-CoV-2 viron. Capturing lots of images of the spike protein from different angles allows for a 3D reconstruction of its structure! https://t.co/vXYiSxjNKY
Incredible magnetic structures in a Fe-Co-Ge thin sheet as the external magnetic field is increased (from https://t.co/PokizELWIH) https://t.co/douNp4Dly3
(more images to come later in the week, stay tuned!)
When the electron beam in an electron microscope hits the sample, all sorts of signals are produced (see the legendary https://t.co/z3UngyGs9L) https://t.co/2whGM1l5AD
We can form different images of the sample depending on which signals we collect. The images shown so far have collected secondary electrons (SEM) and direct beam (TEM). But there's so much more to see!
In the SEM, back-scattered electrons (BSE) can diffract (EBSD) from the crystalline sample. Collecting the diffraction pattern allows determination of the crystal structure and orientation at the beam position ... (see https://t.co/L5UEuAAdBt) https://t.co/JG0bOmxGHM
Here's (A) light microscope image and (B-D) SEM+EBSD of a martian meteroite. Although some features are visible in the light micrograph, the EBSD data more clearly shows areas that are (B,C) highly deformed and (D) mechanically twinned (from @Daly_Planet https://t.co/NKM6FPJ4FA https://t.co/UnvfKL23tp
More EBSD, this time comparing grain structure of an (a-c) additively-manufactured and (d-e) wrought titanium alloy (see https://t.co/Oeond66BVh) https://t.co/7pv67aDpwc
The beam can also knock-out core electrons from atoms. An outer electron can take its place, releasing an X-ray, which we collect in energy-dispersive X-ray spectroscopy (EDS). Here's EDS maps of a multiple principle-component alloy (see https://t.co/3olqFpNzh4). https://t.co/ERXwJW17MO
@the_ScienceTalk Caption says "coloured transmission electron micrograph of carbon nanocoils". Very beautiful!
We can put a saw INSIDE THE SEM CHAMBER to image a surface, cut it off, image the new surface, and repeat. The images can be stacked up to give a 3D view of the sample. Here's the anchoring of spiders silk! https://t.co/zh5gfkxaJ5 (see https://t.co/RdiopvvBo2)
In the TEM, the electron beam can be diffracted by the crystalline order in the sample. We can configure the lenses to project the image onto the screen. Behold: dots and a cube! (from https://t.co/Naj6jtUEBr) https://t.co/Y2uY3cVsSZ
The atom probe is a whole other beast. A very high voltage is used to ionise and rip atoms from the surface of the specimen. We time their flight and catch them on a dartboard, and use their score to determine where they started. (see https://t.co/5ihCyKyiB9) https://t.co/jFUAseFVJl
The result is an "atom map" of the sample. Here is an aluminium alloy showing nanometre-scale rod-shaped precipitates (aka gummy worms) (from https://t.co/wrXOgdS6k4) https://t.co/ffMxv0luBh
Here's a whole range of geological samples. Nanodiamonds!! (from https://t.co/dtiX8GLTO6) https://t.co/XOKrTajLX0
Another aluminium alloy, but this one is dripping with hydrogen. Atom probe is one of the few techniques which can detect hydrogen (so long as great care is taken) (see https://t.co/wqcUEXkOrX) https://t.co/Va3z6b5D8p
This wild three-phase microstructure of a samarium-cobalt magnet (from @bkhm1234 https://t.co/3Yy6OBrns1) https://t.co/LsJYcTagaC
Some electrons lose energy when they pass through the sample, e.g. they ionise (producing X-rays: see EDS above), or they excite something "optical". We can collect the beam and disperse it to a spectrum: electron energy-loss spectroscopy. (from https://t.co/z3UngyGs9L) https://t.co/k65JbwfkNE
The low-loss part of the spectrum includes interband transitions and plasmons. Here's surface plasmon mapping of the cube from the other thread (see https://t.co/wDLcALpQMi) https://t.co/76jxwE6DIt
The high-loss (or "core loss") part includes all the ionisations, and allows for chemical "mapping" similar to EDS, above. Here's distribution of N, O, Ti and Co (cyan) in a semiconductor device (from https://t.co/4mbRRdLLBe) https://t.co/feS4NaDjKi
RT @RealSci_Nano: 🔬🔬🔬Nano to Micro to Macro🔬🔬🔬 Please welcome @ljtegg of @Sydney_Uni for a week of microscopes microscope and some more mi…
This week has been all about microscopy, but here's a short thread on my other baby: X-ray / neutron powder diffraction. Like electron diffraction, X-rays/neutrons can diffract from crystalline specimens ... https://t.co/GNRtVcgSz3
... giving information about the crystalline phases (and their quantity) in a sample. Here are some examples of the power of powder diffraction.
Lead-halide perovskites have applications as photovoltaics and in other light-harvesting applications. Neutron and X-ray powder diffraction was used to accurately determine the crystal structure of FaPBI3 (see https://t.co/Gq8rLDtQXz) https://t.co/6YjGNUfe3F
Powder diffraction can (usually) handle samples containing multiple phases. Here's XRD patterns of samples of W-Al-B showing many different phases, clearly distinguished (see https://t.co/DyFbj99nJZ) https://t.co/w2feBRag7F
Powder diffraction also very good for in-situ or in-operando studies: we change something about the sample and watch how the phases/structures vary. Here we heat reagents and watch as they thermally expand then react to form the product ... (from https://t.co/YMcao1cQrM) https://t.co/3TCsKPTEcZ
... analysis of the pattern at each time step allows us to see how the balance of phases changes over the course of the reaction. https://t.co/wi9I2X73MC
Hydrogen is quite mobile so work like this usually requires a cryogenic workflow: samples are prepared, milled, or transferred while at cryogenic (~-200 degC) temperatures ... (e.g. https://t.co/HWMktXazD7 or https://t.co/pJn5bFOnml) https://t.co/1jAT3Cfohk
I'm using these cryo workflows with atom probe to study (frozen) water. Water is hard to make into a sharp needle so the community has come up with some creative sample preparation techniques:
Water separates from its substrate easily. "Dealloy" an Au-Ag alloy to prepare nanoporous Au. Keep it wet, and use the focused ion beam (FIB) to mill-out a needle. (see https://t.co/uO7wBFn0z8) https://t.co/HUM1SOsbcp
Cool tungsten wire in liquid nitrogen + break it + pipette a drop of water on the fracture surface (which freezes) transfer to FIB + transfer to atom probe. (see https://t.co/zsIjL5M7xS) https://t.co/R6wGox3aXc
The protein ferritin is rispersedin a resin, then FIB + lift-out is used to make a specimen (see https://t.co/N90zaLjE27) https://t.co/LHj5Z2tTFR
Trap liquid between a pre-sharpened tip and individual layers of graphene. This one doesn't even need cryo - the water stays trapped under the graphene, even in air and under vacuum! (see https://t.co/LmPt3qqU9Z) https://t.co/AwOjzXc6q5
Two big conferences coming up for microscopy and atom probe: IMC in Busan Korea, followed up by APT&M in Leuven, Belgium. If you're there, find me (@ljtegg) and say hi!
Huge thank you Levi for a smashing week of microscopy! 🔬🔬🔬 Do give @ljtegg a follow🥳🥳🥳 Would you like to take over this account for a week and feature on Under the Microscope podcast? Contact us here - https://t.co/PF3hvGzTJI @the_ScienceTalk https://t.co/FDd23oeO8K
Anastasiia Mikheenkova
🚗🏎️⚡️🔦🔌Electric Car Batteries🚗🏎️⚡️🔦 Please welcome @Ana_Mikheenkova of @UU_University @UUBeta for a week of science! 👇 checkout conversation between Ana and @svenja_lohmann to know what all is coming your way this week! @the_ScienceTalk https://t.co/X2pC7o870i
RT @RealSci_Nano: 🚗🏎️⚡️🔦🔌Electric Car Batteries🚗🏎️⚡️🔦 Please welcome @Ana_Mikheenkova of @UU_University @UUBeta for a week of science! 👇…
Hello RealScientist Nano followers! This week I, @Ana_Mikheenkova , am happy to take over the account with energetic insights into battery science 🔋! First, a huge thanks to @svenja_lohmann for inviting me! Today I would like to start with me sharing my scientific journey.
I did my bachelor's at Samara Aerospace University, the city where I grew up, and since an early age, most of my interests were around physics, engineering, and space. I was lucky to be granted early lab access.
And I start doing little science projects in the Chromatography lab since my first year of University which I presented at many student conferences. Photo of me with our mini chromatograph https://t.co/dt8WludmHN
At that time, I was over-glamorizing the scientific career path: I saw intelligent and interesting, multifaceted people, who were working to solve people's struggles and constantly travel to meet and exchange with other brightest minds of humanity. Isn’t it the coolest job ever?!
After my bachelor’s I had no doubt but to get more scientific experience and I saw @Erasmus_Mundus joint programmes as an excellent opportunity to study in several countries, meet people from different cultures and learn how to create a fruitful collaborations across countries.
@Erasmus_Mundus The program MaMaSELF (Material Science powEred by Large Scale Facilities has opened me new opportunities. I spent my first year in @UnivRennes1DSI where we delved into fundamental physics behind material science and my second year in @unito with a lot of applied studies. https://t.co/2fHeudsruI
What I valued even more are the internships: after my first year I went to @psich_en in @cv_villevieille group where I discovered for myself an amazing world of batteries. I enjoyed my project on optimization of Na-ion battery and my time in the supporting and diverse community. https://t.co/4xBvqgGR73
@cv_villevieille @psich_en Thank you Claire 😊
Before graduating I felt that I was lacking experience in neutrons and I joined a project that connected my passion and my needs - I was investigating stress in satellite compounds using neutron diffraction at @ILLGrenoble for my master thesis. https://t.co/17HsNt7NN8
After moving between 3 countries in 2 years, I was happy to stay for a little longer as a PhD student at @UU_University where I can finally applied all studied skills of material characterization and apply them to something that can help to fight the global warming- batteries. https://t.co/U68xzVBLCf
And I will come back tomorrow with sharing most important battery concepts 😉 Meanwhile, feel free to ask me any questions about my journey, I am happy to share all I know on getting scholarships and applying for programmes and internships 😊
Today we’ll refresh our knowledge of some of the battery terms. Let’s start from the beginning: we call a battery a device that converts chemical into electric energy using redox reactions. To narrow it down, let’s focus on batteries which use Li (Li-ion batteries). image:iStock https://t.co/XqHqXg8qXF
It is a secondary (rechargeable) battery which uses reversible reactions with Li-ion to store energy. fig:https://t.co/bMWuELalAX https://t.co/P4WUqJLAp4
Redox (oxidation-reduction) reactions involve transfer of electrons between two substances. As a result of gaining or losing electron, oxidation state of the substances changes.
Common example from LIB: oxidation reaction on anode: LiC6 → C6 + Li+ + e- (which describes delithiation of graphite); reduction reaction on cathode: CoO2 + Li+ + e- → LiCoO2 (lithiation of LCO positive electrode).
So far we've mentioned cathode and anode, both of them contain active materials - a chemical which participates in redox reaction. However, they also have inactive materials which also play important role.
A typical electrode coating consist of mixture of active material, binder (polymer which ensures mechanical stability) and carbon (conductive additive to enhance electric conductivity). doi: https://t.co/wqzXqJXO7O https://t.co/HXrkTlTiIS
This mixture is coated onto current collector: aluminum for positive electrode and copper for negative (to avoid lithium loss due to allowing with Cu at low potentials).
Other elements of a typical cell are electrolyte, which lets ion pass form cathode to anode and typically consist of Li salts dissolved in organic electrolytes, and separator - a polymer membrane which isolates cathode and anode from contact (that would short circuit the cell).
Now let's look at the most popular battery terms: 1. (Nominal) Voltage - is the amount of voltage output a cell gives out when charged. It is defined by cell chemistry, which will depend on redox centers of both positive and negative electrodes. Image: https://t.co/PghKDJw7ku https://t.co/PDquGXYOMt
2. Capacity: how much current it can provide to a load or how much charge is stored in a battery. A term related to that is State of Charge (SoC) and Depth of Discharge (DoD). Image: https://t.co/Vf2WrRUT2r https://t.co/V2SKesHqZC
3. Internal Resistance: Resistance of the battery. The higher resistance, the lower efficiency the battery has, and the lower the actual capacity it can deliver as well as it will be problematic to use for high current.
4. Energy density: how size or weight efficient the battery is. The higher energy density, the more energy can be stored while occupying less space or being more lightweight.
And that’s main terminology simplified. Tomorrow we will look at how these useful devices degrade.
How do batteries degrade? Yesterday we checked some important concepts and today we can describe what can go wrong with the device we rely on a lot, especially when it comes to mitigating global warming. image:https://t.co/Kq9YtDTsd4 https://t.co/ce0ISRRHPt
When we say that a battery reached the end of its life, usually we mean that it lost 20% of its initial capacity. Why 20%? Good question 😉 Generally, the degradation of the battery is not linear. After 20% of capacity loss, it fades much faster with rapidly degreasing safety.
As we saw yesterday, a battery has many components: metallic, polymer, solid, liquid, crystalline and amorphous, some contain heavy metals and light elements. It must be a headache to analyze, right? Well, some see problems, and others anticipate opportunities 😉 Joking! or…
To make our lives easier, all degradation mechanisms are split into three types depending on their effect: Loss of lithium inventory, loss of active material, and increase of resistance. Yes, it is simplified but still helpful.
If you ever heard about the ageing of lithium-ion batteries, the first thing you probably saw is this figure. It quite nicely summarizes the main mechanisms and how they relate to the degradation modes. doi: https://t.co/070uRG9nKa https://t.co/ZdafvoMfOx
In real systems, degradation depends on cell chemistry, cell optimization, cycling conditions and other factors. Our recent study focuses on testing batteries from an electric car and evaluating degradation based on cycling conditions check it out: https://t.co/QLYJ6WXXF4 https://t.co/6VATBQ5fIW
As you can see here we highlight some of the mechanisms which are relevant for Ni-rich positive electrode: transition metal dissolution, void formation, formation of CEI (we tested 2 working temperatures and 3 state-of-change windows). Check it out to see more details!
It was also very interesting to study the negative electrode: blend of graphite and SiOx. These compounds degrade differently and it was fun to be able to decouple that!
So for now, we saw some degradation modes and a fancy figure with many mechanisms attributing to these modes. Now let’s see how we can analyze a couple of them. Fig: https://t.co/rtEyOFalsK https://t.co/MonTj7moyM
First al all, it is quite important to take into account testing conditions: ex situ, in situ and operando are the terms we see a lot. They refer to the state of the material we analyze. Let me just put a fun picture so you get the analogy. doi: https://t.co/C54QByTdFA https://t.co/l3XxJ03Dvb
Then, I would say, the two approach to characterize the batteries are electrochemical and material analysis. My biggest passion is the second one, but with we can’t put apart electrochemistry. Not in battery science 😁
So let’s start from electrochemistry. One can do many things: cycle batteries, apply pulse techniques or use impedance spectroscopy. All depend on what you actually want to know. Another thing to take into account is the configuration of your cell.
In some cases, i.e. in real battery systems, we have to look at full cells. Which means that we test both electrodes and their responses vs each other. If we would like to know more about one electrode or the other, the simplest thing is to assemble half cells or 3 ed cells.
In order to understand changes in capacity, increase in resistance or have an estimation of LAM and LLI, chronopotentiometry and follow-up data analysis can be applied (DVA and ICA).
In order to follow time-resolved processes, for example, Li diffusion, perturbation techniques can be used: PITT, GITT, EIS, ICI.
I think my favorite will always be EIS, it’s tricky, involves quite some assumptions, yet, you can learn a lot about your system. I’d also take a change to promote a nice online resource with good educational materials about batteries and electrochemistry: https://t.co/DOd87b6rle
As for the rest, let’s meet here tomorrow and talk about material analysis!
Yesterday we briefly checked on electrochemical methods for battery characterization. Today is the time for material analysis! fig: https://t.co/hZT5GjMQwa https://t.co/udmX4vH15w
When choosing a method for analysis, many factors should be considered: - Scale of studied phenomenon and probing depth - Properties of studied species (light/heavy elements, crystalline/amorphous) - Level of analysis (structure/chemical bonds/etc) - In-house/LSF - Operando/etc
During the previous week, @ljtegg gave a very nice overview of how microscopy and XRD works. Let’s see how it can be applied to batteries.
SEM and TEM are extensively used to study battery materials. Morphology observations to spot degradation, deposition of side products and particle cracking - it is fun to see it all!
One thing is that sample preparation is very important: battery materials from LIB are often air sensitive so proper handling is a must.
As for X-rays, not only XRD can be used: XAS is widely applied to learn about chemical state of atoms, as well as bond and coordination environment. Read more in this nice review: https://t.co/HjAJhaShYE
My favorite example is the study where we looked at charge compensation mechanisms in actual commercial battery materials using EXAFS, TEM and RIXS (yes, oxygen matters 😉). Read more here: https://t.co/nJY3pf4oYV
My PhD is a part of a project called ALINE which stands from swedish abbreviation for Aging of Ni rich Li-ion Batteries. It is a big project which involves @volvocars @VolvoGroup @UU_University @KTHuniversity and @chalmersuniv .
The focus is on analysis of batteries for and from electric cars and trucks. Today we have a project meeting and I got to drive an electric truck, two hybrid ones and electric bus! https://t.co/0Cxp72IWrE
Also I take this opportunity to share some of our results which has been published:
Exposing Heterogeneous Degradation in Prismatic Lithium-Ion Cells: https://t.co/GgG9SP4Rv9 https://t.co/OfMvJT8L7b
Ageing of High Energy Density Automotive Li-Ion Batteries: The Effect of Temperature and State-of-Charge https://t.co/QLYJ6WXXF4 https://t.co/5sqP2Tea61
Resolving high potential structural deterioration in Ni-rich layered cathode materials for lithium-ion batteries operando https://t.co/ph5I4bnkZc
And many more!
A small break from 🔋 to talk about something important: #equality and #inclusion in #science. During my PhD I was a part of Chemistry Dep Equal Opportunity group and PhD ombudsman. Here is a couple of concepts to be aware of and tools to improve the environment in science:
#Discrimination - “the unjust or prejudicial treatment of different categories of people, especially on the grounds of ethnicity, age, sex, or disability”. How to understand that you or someone at your workplace are discriminated:
Check for: - Verbal microaggresions; - Specific attention (being suspected of cheating or not working properly); - Unfair work distribution (academic housekeeping); - Expectation to work overtime; - Oppression: interrupted, devalued, ignored at work-related meetings/conversations
Microagressions - “brief, sometimes subtle, everyday exchanges that either consciously or unconsciously disparage others based on their personal characteristics or perceived group membership”. How to identify them?
Sadly, usually just but knowing what has been actually been said. A couple of examples: more examples https://t.co/c3QdXK3Q5K https://t.co/b0EcGI1dfb
Academic housekeeping - “type of work tasks within university departments that are low-status, time-consuming, largely invisible, and that nevertheless need to be done”. The study published in swedish became a topic of discussion around the world. Sadly, for a reason.
The article focuses on gender based aspects of how academic housekeeping tasks are distributed and shows “that women carry out a disproportionate share of academic housekeeping tasks”. https://t.co/i4PEVX1q6M
Just one more concept to see how it is important to act even if you are not personally affected: #Bystander effect “occurs when the presence of others discourages an individual from intervening in an emergency situation, against a bully, or during an assault or other crime”
Sadly, presence of passive bystanders increase the detrimental effect of the situation. It is important to take an action and it’s also important to know how to do it depending on situation and people involved:
Active bystanders “are aware of when someone’s behaviour is inappropriate or threatening and choosing to challenge it.” And there some strategies one can use:
First, access safety using ABC: “A”ssess for safety: what are your risks; “B”e in a group: It’s safer to intervene in a group; “C”are for the victim: Talk to the person who you think may need help.
If you decided to act, remember there are different ways of doing that. Remember 4Ds: direct, distract, delegate, and delay.
Direct action - is to call on the negative behavior directly, telling the aggressor to stop.
Distract - move attention of the aggressor or the whole group from the situation to something else. It lets the target to also move away towards safe environment while attention is somewhere else.
Delegate - there is no shame to feel to stressed to act right on point, but it is important to ask someone who is in power to change the situation to pay attention to the problem.
Delay - if the situation is too dangerous to be act upon directly, remember to come back to the problem later, when things feel safer: ask the affected person. If they are ok and whether they need help.
I believe that little steps lead to big changes. We are not always prepared to challenges we are facing. However, spreading information on what are the signs of discrimination and how to act if you encounter or witness one, can evolve the working culture of #academia for better.
Today is the last day of our 🔋 battery journey. Thank you for this time and I am happy to stay in touch with you at my @Ana_Mikheenkova account. Don’t miss a great opportunity of visiting Sweden and join ECS in Gothenburg @ECSorg (Submission is open). https://t.co/lawgX3412y
Here I am happy to share a sneak pic of beautiful Gothenburg I captured last autumn during #Nordbatt conference (by-annual battery conference which I definitely recommend to participate!). https://t.co/7kJpQBZ9vU
Huge huge thank you to the super electrifying @Ana_Mikheenkova for a smashing week of battery science⚡️🚗 Give Ana a follow everyone, right now!🥳 Do you want to tweet from this account and feature on our podcast #UnderTheMicroscope? Contact us here - https://t.co/zxT6r6XxUb https://t.co/XlOUXjU6T8
Antonio Manesco
"Simulating the Future of Quantum Materials" Please welcome @AntonioManesco for a wonderful week of quantum computing, quantum materials, topological insulators, 2Dimensional materials. https://t.co/yYt8M0yVgY
I am a postdoc @QuantumTinkerer, a theoretical/computational physics group @tudelft. This is a joint group between two PIs: @AkhmerovAnton @QuantumNanoTUD and Michael Wimmer @QuTech_news. We study meso- and nanoelectronics. But I will tell you more about it later.
I got my bachelor's and PhD degrees @usponline, more specifically @eel_usp. There I was also very often collaborating with the @computeeluspbr1 group. Btw, especially if you know any Portuguese, go follow @gbrlwbr, one of my PhD supervisors, very active in science outreach. 😀
Soon more about my current/past groups!
Hello everyone! Today I (@AntonioManesco) will take over this page to tell a bit about my science. So let's start with a thread about me so that you know what to expect to read about this week.
I am a postdoc @QuantumTinkerer, a theoretical/computational physics group @tudelft. This is a joint group between two PIs: @AkhmerovAnton @QuantumNanoTUD and Michael Wimmer @QuTech_news. We study meso- and nanoelectronics. But let's not dive into it later on.
I got both my bachelor's and PhD degrees @usponline, more specifically @eel_usp. There I was also very often collaborating with the @computeeluspbr1 group. Btw, especially if you know any Portuguese, go follow @gblrwbr, one of my PhD supervisors quite active in science outreach.
Next posts about the current/past research groups I've been at.
Now let me talk a bit about how I started my academic experience in Brazil. Which goes all the way back to my bachelor's... @usponline has many campi spread over the state of Sao Paulo. And I went to study in one (@eel_usp) of the newest campus in a small city called Lorena. https://t.co/lhbXouV2sr
Well, it was only new as part of @usponline. But as a research institute, it existed for much longer. There is where Brazil started ethanol fuel production, and also the first niobium refinery plant.
I got my bachelor's in Engineering Physics, a program that was offered by the Materials Engineering department. Fun fact: I was in the first class of the course and graduated alone slightly earlier than expected. So today there's a sign with my name in there. https://t.co/Sx9yE9QrxF
But why does this department host a Physics-oriented bachelor program? Well, they had a built-in refinery back in the day. Which attracted many physicists working with superconducting materials. (Stay tuned to learn more about superconductivity!)
And that's exactly how I started: working with applied superconductivity with a Scientific Initiation fellowship. As an experimentalist! I shared a bit of my experience in the podcast episode. So go check it if you want to know more! https://t.co/cYmW7BBB13
But how did I end up in the Netherlands? It all very indirectly started at the end of my bachelor's, when I got to know the PIs in my group through an online course that they organized. The course material is still online, and I highly recommend it! https://t.co/OLOZutM4Mp
I was about to start a PhD with @gblrwbr and Durval Rodrigues Jr. After this course, I decided that I wanted to do something related to topology.
During my PhD, we decided that I should visit an established group in the field. So that's how I came to @tudelft as a visitor in @quantumtinkerer. After I graduated, I came back to the group as a postdoc and have been here since. https://t.co/4cS6TOfsEQ
To end the day, let me talk about the last group that I was briefly part of. For a month, I was part of the (experimental! 😱) group of @FatemiValla @CornellAEP, located in the beautiful campus of @Cornell.
We both like to study two-dimensional materials and superconductivity. So we started doing it together in the summer of 2022 when they hosted me as a visitor. Being part of an experimental group as a theorist was quite fun, interesting, and hard: real life is complicated!😄
Today we're talking science! Have you ever thought about how we got from these huge computers in the past to devices that are so small that you can fit in your pocket? What if I say this was possible because of Quantum Mechanics? https://t.co/emt7d5dGuL
I need to explain roughly how computers work. Can I do it in a single tweet? They are machines that convert a signal (speaking, typing) into a string of 0's and 1's. These digits are called bits. Some math happens in the computer and it returns something else (image, sound).
"So computers do math?" Yes. But in a very different way. The input signal is converted into an electric signal: - 0's: no electric current passing - 1's: electric current is passing The "math" is how the electric signal travels in the complex circuit inside the computer.
So we need an electronic device that allows current to pass or not. Something like a water valve, but for an electric signal. These exist, and is how we used to do electronics in the past. https://t.co/3JbLvqBYjU
But the image in the previous tweet also shows something. These electronic valves are large! Is not very easy to shrink the size of a computer if inside it there are a bunch of empty glass bulbs. That is definitely not how we make a cell phone!
So let's think again. It would be great if we had a tiny piece of material that we control if it is a conductor or insulator of electricity. That'd make our valve much smaller! So what are really conductors and insulators?
To answer, we need to talk about atoms. In school we learn that atoms are constituted by two parts: a heavy positively-charged nucleus; and a bunch of light negatively-charged particles, called electrons, orbiting the nucleus. https://t.co/RKRSy9ZOz5
But these electrons cannot orbit as they wish. Quantum Mechanics says that they can only occupy orbits with a well-defined energy. Also, electrons don't occupy an orbit where there's already another electron.
So if you put atoms together, the orbits cannot be identical to how they were before. That would mean many electrons occupying identical orbits. As a consequence, the energy of these orbits changes by a bit, forming what we call energy bands. https://t.co/geTgvp9PMr
That's what happens inside any material. And whether it is an insulator or a conductor depends on where the last electron is. We start populating the bands with lower energy. And if the last electron we put is in the middle of the band, we call it a conductor. https://t.co/XSlOMnnl1r
If the last electron is at the very top of the band, we need a very large energy to put it in another orbital. And because of this energy gap, we call the material an insulator. https://t.co/J97UeGWEsz
But there are materials with a gap that is not so large. And these materials we can actually control if they should behave as insulators or conductors. These materials are called semiconductors. We found what we needed! https://t.co/2DyVADOArq
That's how the transistor was created -- the electronic valve that requires no empty bulb. Since then, there were basically no limits on how small one could make a computer. And that's how you are reading this thread on a much smaller computer!
Have you heard all the fuzz about #LK99 some time ago? If you didn't: some researchers claimed that they discovered a room temperature superconductor. But what are superconductors anyway?
More than 100 years ago now, Heike Kamerlingh Onnes was working in a laboratory in city nearby (Leiden) trying to obtain get lower and lower temperatures in his lab. Eventually, he managed to liquify helium. A process that happens at 4.2K (-269 Celsius)!
And what do you think a scientist do when you get such low temperatures? They (responsibly) throw whatever you can in there.
He was particularly curious about how metals conduct electricity at low temperatures. Especially if these metals are very pure, their resistance should SLOWLY drop more and more.
To purify metals, you need to melt them and let all the impurities evaporate. So what are the easiest metals to melt? The ones that are already liquid in room temperature. So Heike choose Mercury. https://t.co/7d6nlWx9j9
But something unnexpected happened: the resistance dropped SUNDENLY to zero! After many checks, he concluded that this was indeed happening and the phenomenon was coined superconductivity.
It took from 1911 to 1957 for physicists to find an explanation for this phenomenon. And even today, this explanation only holds for some materials. And guess what: the reason why it happens is because electrons ATTRACT each other! 😱 https://t.co/6mXVw2QK6A
It turns out that at very low temperatures, electrons don't have a lot of energy. And when atoms vibrate by a tiny bit, they can cause electrons to attract each other. As a consequence electrons move in pairs (called Cooper pairs) inside a superconductor.
We don't have yet a room-temperature superconductor. But we already use superconductivity in many devices. Stay tuned and you'll learn more about where we use them!
Today I’m doing something different: I’m in Leiden attending a PhD defense. And the topic of the thesis inspired me to write about my favorite material today: graphene!
Let's start with graphite. Yes, the same material as the one in your pencil. If you look into the atomic structure of graphite, you will notice that it consists of many layers of carbon. Each layer is organized in a honeycomb structure. https://t.co/CoLJlWUbQS
In fact, this structure is the very reason we use graphite to write. These many carbon layers detach easily from each other. As a consequence, if you slide it on paper, some layers just stay there.
It's actually so easy to detach these layers that with scotch tape and some patience you can isolate a single layer. And that is how graphene was made in a lab for the first time. https://t.co/vKDJcRNARg
But what is so nice about this material? Well, many things. I will list the ones that are quite important for my research.
1 - It is easy to combine it with similar materials Many materials out there have a similar layered structure. And in the same way that is easy to detach these layers, is also easy to combine them.
For example, we can encapsulate graphene with an insulating material to protect it from the external environment. This idea is actually what enabled graphene-based devices to work much better than other materials.
We can also use this property to combine graphene with other materials. For example, we can use a layered magnetic material to make graphene magnetic. Or a superconducting material to make it a superconductor.
2 - Electrons move as if they don't have mass Electrons inside a material can behave in a very different way to their behavior in free space. In particular, electrons move in a graphene crystal as if they were massless particles.
3 - It is an actual two-dimensional system Before graphene devices were fabricated for the first time, the only way to confine electron motion in two dimensions was by growing complicated crystals. Graphene is already two-dimensional, so no engineering is needed.
4 - You can twist! Since these atomic layers are weakly bonded to each other, you can twist them. In fact, that changes a lot of the electronic properties of graphene. For example, with the appropriate twisting angle, you can make it a superconductor! https://t.co/YFPgQF979C
There's way more, and I could keep writing. But I think you got why I like this material so much!
To start, insulators and topological insulators have something in common: they both have a band gap. But what happens when we put insulators in contact with each other?
Well, if all of them are trivial insulators, nothing really happens. For example, nothing really fun happens if my coffee mug is in contact with the table it's sitting on: both are gapped and when they are in contact their interface also has a gap.
Now if my mug was made out of a topological insulator material something curious would happen. The energy gap of a trivial and a topological insulator is inequivalent. Therefore, as you go from a point inside the mug to a point inside the table, the gap must close and reopen.
The energy gap closes at the interface between the trivial and the topological insulator. And, as you learned before, if there's no energy gap, the interface becomes an electric conductor.
Even if you mess up with the table and the mug, they will still have an interface. Since the interface doesn't care about the quality of any of the insulators, this conducting layer is a very good conductor!
Hi again! I was out yesteday for an event from my department. But now I'm back! I explained to you how an insulator works earlier this week. But what is a topological insulator? https://t.co/KwUoZjQfp8
To start, insulators and topological insulators have something in common: they both have a band gap. But what happens when we put insulators in contact with each other? https://t.co/cmhK5Xg7UW
Well, if all of them are trivial insulators, nothing really happens. For example, nothing really fun happens if my coffee mug is in contact with the table it's sitting on: both are gapped and when they are in contact their interface also has a gap.
If my mug was made out of a topological insulator material something curious would happen. The energy gap of a trivial and a topological insulator are not equivalent. Therefore, as you go from a point inside the mug to a point inside the table, the gap must close and reopen.
The energy gap closes at the interface between the trivial and the topological insulator. And, as you learned before, if there's no energy gap, the interface becomes an electric conductor. https://t.co/XNFtpxATDX
Even if you mess up with the table and the mug, they will still have an interface. Since the interface doesn't care about the quality of any of the insulators, this conducting layer is a very good conductor!
Now that I told you about topological insulators, time to explain what are topological superconductors and Majorana particles! https://t.co/FG45OanGJ4
So, I just told you that topological insulators have an energy gap different from a trivial insulator. The same applies to superconductors. But how can a conductor have an energy gap and still conduct electricity?
Well, I also told you earlier this week that electrons inside a superconductor pair with other electrons. So we cannot really put one electron at a time in a superconductor... https://t.co/zqBbnHzlHB
...unless this electron has enough energy. This energy is what we call a superconducting gap!
The rest works just like an insulator. At the interface between a topological superconductor and any material with a trivial gap, the gap closes. But differently from a topological insulator, the particles moving at the interface are not electrons, but Majorana particles.
These Majoranas are part of a family of particles called anyons. And because of that, they can be used to build fault-tolerant quantum computers. https://t.co/qaLRAliov0
Obtaining Majoranas in the lab is a very complicated task. And is for example what many of my colleagues @qutechNews do! And in fact, they just made a simpler version of these Majorana particles recently. https://t.co/58ewfDQcjl
These devices are very similar to the ones I simulate at work. And I want to end the science section today by talking about a recent work that I co-authored that was inspired by these experiments. https://t.co/bNOarp1MlQ
But I already wrote a thread about it when this work came out. So I'll be a little lazy and link it here for you. 😄 https://t.co/7Vofmvhuo3
Thank you Antonio for an smashing week of #materialsscience with topological insulators & quantum computers. Also taking us on journey from Brazil to the Netherlands. Everyone, give @antoniomanesco a follow!🥳 @QuantumTinkerer @QuantumNanoTUD @tudelft @the_sciencetalk
Dimosthenis Katsis
✨Space travel, heavy ions & electric cars✨ Please welcome @dimoskatsis for an incredible week of the engineering side of #materialsscience Check out the interview with Dimos to know what is coming your way this week!👇 @the_ScienceTalk @MySci_PK https://t.co/zXQRvlawQ4
RT @dimoskatsis: Energy lost in transmission and distribution accounts for 6% of the total energy generated in USA. 4% in distribution alon…
RT @dimoskatsis: A pleasure talking to the host of @RealSci_Nano today! I wanted to share a link to the awesome team building hybrid electr…
RT @RealSci_Nano: ✨Space travel, heavy ions & electric cars✨ Please welcome @dimoskatsis for an incredible week of the engineering side of…
RT @ElectraAero: Visit Electra at @NBAA-BACE2023! Want to learn more about electric aircraft? Why is hybrid-electric the best solution for…
Eliminating electromagnetic interference from electric propeller drives using nano-crystalline magnetic "bracelets" that slip over the power cables (essentially high permeability magnetic cores) https://t.co/yv5QeOkQRE
@MySci_PK @dimoskatsis @the_ScienceTalk It has been a while since I did my tritium work but a good example is a retired product from Sparkfun: https://t.co/tHIq8yIRsf. Also check out https://t.co/caVg4MqFoh They are still active in this space.
Antonija Grubisic-Cabo
💋💋💋KISS of light💋💋💋 Please welcome @CaboAntonija, our veteran, on @RealSci_Nano for an action packed week of #nanoscience 🥳 @ZernikeInst @univgroningen @the_ScienceTalk @MySci_PK #UnderTheMicroscope Watch 👇📹 to get a head start for this week! https://t.co/BW82VDSq8h
Hello everyone! This is @CaboAntonija and I will be taking over the account this week. We have a lot of topics to cover, including where I am now, my recent research and a bit about teaching and workshops/conferences as that's what I'm busy with this week!
At the moment I am actually in lovely Leiden, attending a workshop on #Quantum #Magnetic #Materials in @lorentzcenter that I co-organised with @dsoriano_david @mhdguimaraes and @ZeilaZanolli It's going to be an exciting week with a lot of discussions! https://t.co/wC9Mhy10Ef
@lorentzcenter @dsoriano_david @mhdguimaraes @ZeilaZanolli @lorentzcenter workshops are unique in their focus on interactivity and discussions, and our workshops is not an exemption. We have a lot of discussions sessions scheduled, introductory seminars, and even a tutorial from @Qnami_ https://t.co/5a37ADzkRu
Our first day of the workshop is over, but what are some of the things one needs to do when organising a conference? The list is quite long, and I will mention just a couple of things starting with time and planning.
Why am I starting with this? Because we started planning our @lorentzcenter workshops already in December 2022! Of course, you start slow - by deciding on the topic and finding people to co-organise with you.
@lorentzcenter We had to write an application to Lorentz Centre for our workshop - and this included description of the workshop, topics we want to cover, tentative planning and list of activities we wanted to have- and list of key participants.
@lorentzcenter This all goes for the review, and then we got comments from the reviewers and adapted the final draft based on this - similar to the case of an article under review. And once you are awarded a workshop week, that's when the real work begins!
@lorentzcenter You have to finalise the participant list to know how many people will attend (in our case we had a limitation to 55 participants), and you also need to ensure that all of your key participants can attend. If not, you need to go for a backup plan!
@lorentzcenter Of course organising a conference costs money, so dealing with funding is an important step. We are lucky that we got some funding from @lorentzcenter and they also provide us with space, office and an amazing organisational support!
@lorentzcenter We still had to obtain additional funding, in this case it came from our personal grants andour industrial participants. How to get in contact with companies? It helps if you know someone working there. It is also very important that there is a good connection their work.
What did we use this extra funding for? We are covering costs of our podcast, use it to provide lunch for the participants, and to provide travel support for PhDs and postdocs who needed it!
What are other things you need to do when organising a conference? Well, you select speakers/key participants. We took great care to cover our key topics well, and to have representation of all the fields, (including theory vs experiments), seniority, gender and nationalities
You actually need to secure your speakers quite early. Of course, things might change closer to the date, but the sooner you contact your speakers, the better! Especially if they are travelling from far away, or have a heavy teaching load and need to time conferences well.
Other things we did included making a schedule, selecting a place for conference dinner (with a lot of help from @lorentzcenter ), arranging for poster sessions and preparing questions - and participants for podcast recording.
For everyone wondering how come Tweets are posted so late - I actually just got back home in #Groningen, as I have teaching related obligations in morning, so I will have to go a bit back and forth between Leiden and Groningen. Luckily, it is possible to work on the train 🚆
Tomorrow I'll tell a bit about teaching, as that's what my day will be about, and any other interesting things!
It's going to be a busy morning with half a day course on assessment styles in teaching, but everything is better with a nice cup coffee. Luckily wr got the place making the nicest flat while in the country on campus 😄☕️ https://t.co/dwqSrY7VjE
RT @CaboAntonija: This week you can follow my Tweets voa @RealSci_Nano profile! We've talked a bit about conference organising, and today w…
My morning has been mainly dedicated to teaching related activities, but I wasn't actually teaching. So, what was I up to? https://t.co/cpFVGwuffZ
I started working as a tenure track assistant professor @ZernikeInst @univgroningen in 2022. My focus is on research, which means that 60% of my time is dedicated to research, 30% to teaching and 10% to academic service.
Most of the professors in the Netherlands need to obtain a University Teaching Qualification (UTQ, or BKO). How you get it depends on your University. In case of the University of Groningen, we take classes given by education experts, have homework and a final portfolio.
Today I was taking classes on modes of assessment, advantages and disadvantages different modes and some mistakes that are good to avoid when making exams. The classes are for all of the lectures, so you might end up in a group with people working at a very different places.
So far I've been in groups with lecturers from economics, law, history of architecture, medical school, computer science- and one fellow physicist. It is an good place meet your fellow colleagues, and see how different teaching can be. But sometimes it can be very difficult.
We use different language, departments have different lecture modes, and we might not even know anything about the field of the colleague. I'm usually always happy when I end up in a group with colleagues from #science and #engineering faculty, as we can talk easily.
These course are not completely theoretical. We actually have to time it well, as we need take certain moduels while we are teaching, as we have 2 experienced people to come and observe us while teaching. One is am expected colleagues, another our teaching coach.
Yes, we got a coach 📢 It is typically an education expert that is supposed to track our progress, and help us with pur portfolio. So far I've completed my teaching and design modules, and only have assessment left. Then I can write my portfolio- and hopefully get my UTQ! 🤞
How much do I teach? I'd say a lot, bit it is subjective. And depends how you count hours. I am a coordinator and lecturer for 2 MSc courses, Surfaces and Interfaces (it's basically what I do in the lab 😃) and Nanomaterials:Synthesis and Engineering.
I'm also coordinator and lecturer for a BSc course Physics Instrumentation and #Technology . These latter 2 courses are also brand new, so that makes them quite handful. I also give a couple of lectures in 2 more courses, one BSc level and another MSc.
Teaching for first time takes a lot of time - at least me. On average, I'd say it takes me 8 hours to prepare lectures, slides included, for 1 lecture (2x45 min). You need to make an outline, check that it fits well with learning goals and student background, make slides
How long does it take for you to prepare lectures when teaching a course for the first time #AcademicChatter
I am back in Leiden and ready to do some work before bedtime. But first, a bit more about teaching! https://t.co/MwEar6320o
Besides my regular teaching duties, I'm also a member of a curriculum committee for BSc in Physics. At the moment we are looking into possible changes we want to make in our curriculum. Being a member of a curriculum committee is actually an excellent way to learn how things work
Before coming to the Netherlands, I've only been here as a tourist, so I had no idea about the curriculum, how the semesters are arranged, and even what exact courses students take. As a new PI, you don't have much spare time to read up on this
But as a curriculum committee member, it is kinda your job to read up on these hings - and it counts in your service hours, so it is a good deal. So what do we do in this committee?
We look at the curriculum as a whole, courses that are offered and input from the students, and can propose changes. We can suggest that courses are rearranged, changes, removed from the curriculum or propose new ones.
Now, we don't exist in vacuum! We have representative members from each physics track, we work together on a plan - and then discuss it with our colleagues. After that, we either can write our report, or we gotta go back to the drawing board.
You might wonder how long this takes -and the answer is that it varies. We do need to finish before Christmas as that is when the plan for the next academic year (teaching wise) is made, so we do have a hard deadline!
You might have noticed that I am mentioning "plan for the next academic year", and that it is basically done almost a year in advance, but what is that? https://t.co/gqTNo7tmjG
Well, we actually make plans for the courses close to a year ahead! I don't mean that we have a schedule or start working on the lectures, but we need to know which courses are taught and when, so that students are informed in time.
We also need to make a description of the course, with learning outcomes, what programme are they for, and even modes of assessment. This can be quite a handful if you are teaching for the first time, but it gets easier with time - as long as you are teaching the same course 😅
These things can be changed every year - and are actually often updated. Maybe you decided to switch from written to oral exam, or you decided to change the book you use, or learning outcomes - you gotta plan it a year ahead!
And with this, it is time for me to sing off for tonight and finish my conference abstract. I might even work a bit on the @ERC_Research grant. Deadline is next week, and time is flying! Anyone else also writing now? #AcademicTwitter
Did you know that @UniLeidenNews has a lot of cool historical exhibits, including original second generation #helium reliquifier? Leiden is actually the place where Heike Kammerlingh Onnes liquified He for the first time in 1908! https://t.co/tCTWYlWBsv
For those of you whose watched the Oppeheimer, you might remember that at some point he spoke a bit of Dutch in the movie. He actually learned Dutch for a seminar at @LeidenPhysics There's actually a wall here with signatures of speakers. What names can you recognise? https://t.co/OdTCLLYgED
Poll results! It seems that for the majority it takes 5-8 h to prepare lectures for the first time, with a close runner up of 8+ hours. So it is a really time consuming job that gets easier 2nd time you teach the course! People with 1-3h preparation time, what is your secret? https://t.co/Gyr4Li6KZX
Today's topic - my recent paper that I am super excited about and that I already mentioned in the podcast with @MySci_PK ! In Situ Exfoliation Method of Large‐Area 2D Materials - also known as KISS method (kinetic in situ single-layer synthesis) 💋 https://t.co/8yaj7A6wla
This is my first work that came out since I joined @ZernikeInst , and it was mainly done when I moved there. And yes, this is the work done with the international team of scientific besties 🥰💜
@ZernikeInst What is this method about? Well, it is an #exfoliaiton #method that uses atomically clean surfaces as both a substrate for 2D #materials and a sort of a sticky tape for their exfolation
Method is made to really work well for different #surface #science techniques, as that is my main branch of work, and all of the tools are simply tools you would find in your average surface science #lab!
How does it work? Well, we take a substrate - in our case often a single #crystal metals, as we like conducting surfaces, such as Au(111)🥇 and Ag(111)🥈and we use sputtering & annealing methods to make them extremely clean. All done in ultra-high vacuum!
In the meantime, we also prepare a layered crystal that we would like to exfoliate in a 2D form, let's say WSe2. How do we prepare ti? Well, we use a little pin- or a sticky tape (!)- to remove top layers in ultrahigh vacuum, so that crystal also has super clean surface
And then we simply bring these 2 atomically clean surfaces in contact and make them KISS 💋 We do have a little addition - layered crystal is on a sample holder with a spring- to make it easier to aling things, and to know for sure when things are brought in contact.
Once you separate them, you are left with your layered crystal AND substrate that has large area 2D film (in our example case of WSe2). Large area is the key here. All methods that I use usually require samples of at least 200 um, preferably larger. and KISS method makes them!
Sounds quite neat, right? We also tried it on semiconductors (Ge), and also on air sensitive materials such as WTe2, and it works like a charm! We've done these measurements at a couple of places @ZernikeInst @KTHuniversity and @AarhusUni_int and it worked quite nicely!
@ZernikeInst @KTHuniversity @AarhusUni_int We managed to measure the electronic structure, which is one of the most interesting things to me, and it also seems that it is interesting to other people in the surface science community - which is what we hoped for!
@ZernikeInst @KTHuniversity @AarhusUni_int There is already a work on @arxiv by M. Bianchi from @AarhusUni_int using KISS method to exfoliate CrSBr https://t.co/l7l5VlDN1R Very exciting thing!
@ZernikeInst @KTHuniversity @AarhusUni_int @arxiv Now, let's not forget the scientific team of international besties! We know each other from our PhD and/or postdoc time at Aarhus University, where we all worked with Philip Hofmann. And, as you can see, we are super excited about the outcome of our experiment! https://t.co/1uYLiiZx9p
@ZernikeInst @KTHuniversity @AarhusUni_int @arxiv How international is the team? Well, work location wise we are close and far! Charlotte is now @CLF_STFC , Marco is @AarhusUni_int , Matteo @UBC @SBQMI_UBC , Maciej @KTHuniversity and I am @ZernikeInst @univgroningen And they are all amazing people, and brilliant scientists!
If you are interested in this work, please read the article - we added A LOT of details there about the method, and quite a few examples, to make it as easy as possible for others to use it as well. And article is also #OpenAccess !
If you are not really in the field of surface #science, but still think that it sound cool (I promise, it is! 😎) you can also read one of our popular science articles about it Producing large, clean 2D materials made easy: Just 'KISS' (https://t.co/VKoAblBS9z)
And now I'm back to working on my @ERC_Research grant beforegoingfor a workshopdinner. It was announced today that the ERC deadline is extended, so I wish luck to everyone writing!
RT @RealSci_Nano: Poll results! It seems that for the majority it takes 5-8 h to prepare lectures for the first time, with a close runner…
Learn a bit about our KISS paper on @RealSci_Nano ! https://t.co/07uzDSI2IM
@sensemolen @LeidenPhysics No! I was looking for his signature today. I guess I need to try harder tomorrow! :)
@IvovanVulpen @4TU_HTM @LeidenPhysics @HansHilgenkamp @FeringaLab @NynkeDekkerLab @ZernikeInst @cees_dekker @QuTech_news @CburgesCliff That's really cool! :)
@4TU_HTM @LeidenPhysics @IvovanVulpen @HansHilgenkamp @FeringaLab @NynkeDekkerLab @ZernikeInst @cees_dekker @QuTech_news workshop, I can even ask him where his signature is 😃You got good eyes! I saw@FeringaLabsignature, but not others. We are actually having Bart van Wees give a talk tomorrow@lorentzcenter
Our workshop is going really well, with a lot of exciting talks and discussions. Today topic is spintronics and its potential #applications. It quite busy day, though, as today we are also filming 2 podcast episodes with some of the participants! https://t.co/OdRlNLhUhO
I'm very glad that my colleague @dsoriano_david is experienced with recording #podcasts, as it's not one of the skills I have 😅 I will join one of the episodes as a guest, explaining "how do #magnets work " together with @SolidStChemist and @DBladwell.
@dsoriano_david @SolidStChemist @DBladwell What was I helping with during our @lorentzcenter #workshop? My job was to introduce rules for our vision #article on 2d #quantum magnetic #materials which is one of our planned workshops outcomes! I hope we can write a nice one, as it's not so easy to coordinate 50 people 🙃 https://t.co/ewB67jNA2z
I'm also a very proud #PhD supervisor this week. One of my PhD did an elevator pitch at the conference, and another presented a #poster Both did an amazing job 👏 😀
@sensemolen @LeidenPhysics If I fail again, I might have to ask you for help :)
We've had a second round of elevator pitches today, with excellent pitches by MengXing @SBQMI_UBC , now @Radboud_Uni , Sergio and Falk @UvA_Amsterdam , who told us about their #experimental work https://t.co/zwc4g9PjfA
And also David from @dsoriano_david group telling us about #theory, and back to experiments with the pitch of Maurits I enjoyed a lot all of the pitches, and it was a good advertisement for the posters! https://t.co/A7R1kVwh5k
@sensemolen @LeidenPhysics @semontis helped me find it! 😄
Conference is proceeding in spintronics fashion, but afternoon is reserved for the experimental point of view. We will wrap things up with a #panel discussion where we will discuss future trends in #fabrication and #characterisation of 2D #quantum #magnets https://t.co/uLptvDmgaP
We will draw inspiration for our discussions from amazing introductory talks that gave an overview of the field, including talks by Myrta Grüning @ETSFlab and Bart van Wees (his name is on the @LeidenPhysics wall!) @ZernikeInst @groningen https://t.co/x6CUoPnzjb
It's #podcast time! If you are interested to learn what is special about 2D #magnets and what are some of the challenges, you are in luck! We're recording a short episode on #fundamental properties of 2D #quantum #magnetic #materials @mhdguimaraes @ZeilaZanolli @lorentzcenter https://t.co/xHWtxeZGrB
Also thank @jfrossier for joining, excellent episode and I'm looking forward to hearing it!
@AntonioManesco @mhdguimaraes @ZeilaZanolli @lorentzcenter I will share it once it's ready!
We'll have 2 more episodes, one about possibles applications of 2D #Quantum #magnetic #materials, again with an amazing host @mhdguimaraes , and our spintronics expert participants @semontis , Jose and Marcello https://t.co/QKDjyD11Xf
@mhdguimaraes @semontis And the final recording was our first episode, aimed at general #audience which could be described as "how do 2D #magnets work"? 🧲 I quite enjoyed recording it with @SolidStChemist, @spectecals and our excellent host @DBladwell https://t.co/d8hdXWtkHo
It's the final day of our @lorentzcenter workshop on #quantum #magnetic #materials We're kicking it off with a plenary talk by @SarojChalmers @chalmersuniv https://t.co/q28vwx1K5l
And before wrapping things up, a panel on spintronics and optics with @SarojChalmers @dairymilka @ymblanter Jose and Rembert, and our chair Matthieu https://t.co/XKPmU04bBb
Our #quantum #magnetic #materials workshop just finished, and it was even better than we imagined! You can see that the organising team @dsoriano_david (unfortunately missing in the pic) @ZeilaZanolli @CaboAntonija @mhdguimaraes is quite pleased 😀 https://t.co/Lc7V3I25qx
After saying goodbye bye to our participants, I'm on my way back home to #Groningen and will work a bit on the train 🚆 There's quire a few things to do, send final remarks to attendees, catch up on emails and papers 📃
While I really enjoyed our workshop, I am also looking forward to being home 🏡 Unfortunately it's going to be a working weekend, but I'll try to also get some relaxing, hygge time. #AcademicTwitter what do you do as a hobby/to relax?
Hello everyone #AcademicTwitter ! What are you up to this #weekend? For me, it will be a workign one, finishing @ERC_Research Starting #Grant proposal, and working on some articles. I did manage to sleep in, and have a nice cup of coffee!
And speaking of coffee, it is an important tool in our #scientific work, I'd say! So let's make a poll of what team are you regarding beverages!
@vixklen @ERC_Research Thanks a lot!
@spencer_jolly @ERC_Research Yes, I did. However, I already made family holiday plans, and I am not planning to cancel those :) It is nice that deadline is extended, though.
It seems that majority of people here are #coffee fans! https://t.co/hAEI1qZxcn
As the last poll of this week, #AcademicTwitter how do you feel about music while writing grants/papers or simply working? I love it, and I even have specific music I listen for different tasks (although all of it is metal 😃🤘🤘)
As today is my last day here, I thought I will tell you a bit about how my career changed since I was here 2-3 years ago (also week 42!)
Last time I was Tweeting from this profile, I was a #postdoc @KTHuniversity . That was also during COVID19 time, so I have to admit that I did not see too much of #Stockholm and #Sweden. Quite unfortunate as it is a country with beautiful nature.
I was there on a 2 year postdoctoral fellowship,with a possibility of extension. Not to bad of a deal (no one wants to move during a pandemic...). During that time, I received an email via a mailing list advertising a tenure track position @ZernikeInst @univgroningen
I've never been to Groningen at that point, but the position looked perfect to me, as it was really in the field that I was interested in - ultrafast #Science And I even had a background in it! I was considering whether to apply or not, as I wasn't sure I really stand a chance..
But I thought positions that sound perfect don't appear that often, and I can at least use it as a practice. It definitely helped to have a supporting partner -and supportive work #friends who were telling me to definitely apply.
I took it as a bit of a research project - I checked what is all the information they need, and how it should be written: CV, publications, cover letter, research and #teaching statement... I also asked friends for examples of their applications to have an idea how they did it.
After being on a hiring committee myself - I can tell you that (at least at my university) all of the requested information is relevant. Yes, we are the most interested in your research (for research position), but we also really care about your teaching, and collegiality.
When preparing for an application, I also read about the university, and the institute I was applying with. Who works there, can I collaborate with someone? And also, what are some classes I could teach. It is also good to check possible funding you can apply with.
And then I did my best, sent an application, and got a glass of wine! 🍷
Some time later, I was informed that I am shortlisted, and that they would like to do an online interview (remember, COVID19 time...). This was both exciting, and a bit terrifying. Luckily for me, I have great friends and colleagues who helped me prepare.
I was scheduled to give a seminar to the department, and then a 5 min presentation on my research and teaching vision, respectively.
I made several different versions of each, until I was happy. And I asked people for help. My PhD supervisor is amazing, and he checked my research plan and my seminar. Gave really helpful advice.
I had a meeting with my former colleague about teaching, and I even had a chat with two former collaborators who work(ed) in the Netherlands to prepare better. If you can, do ask people for advice. Most of the time people are happy to help you, and want to see you succeed!
I am really privileged to have an amazing #PhD supervisor, and great friends from my PhD time that I consider family at this point who helped and supported me in this journey. If you are not as lucky, you should still try to contact people you know.
Maybe you collaborated with someone who work at the place you are applying at, or you met someone at the conference some time ago, and you had a great discussion? Do contact them and see if they are willing to meet with you!
And don't underestimate importance of all the things they asked for in the application. In my interview, everything was covered - from research to teaching and management. One of the committee members was a senior master student and they had a lot of questions about teaching.
Of course, before doing online or in person interview, check who you will be talking to, so that you can prepare. It is your interview, sure, but you are also interviewing them! You might end up working with these people next 30-40 years so take the opportunity to ask questions.
I've discussed my research, teaching, even outreach with the committee members!
If interview is online - plan to have an evening off afterwards. It is an exhausting process even if you have good conversations and never leave your room/office. In person, well, it is even more exhausting, but you do avoid possible internet connections issues 🫣
Something I will not go in details, but is also important, is the part when you are offered a position and need to negotiate your contract/starting package. It varies A LOT from a place to a place, even in the same country. For this, you do want to talk to someone, if you can.
And you want to talk to someone from at least the same country - again, as this vastly differs from a place to a place. Did I do a great job negotiating? Don't think so, I kinda sucked at it... But I am happy with there I am. My colleagues are great, and #groningen is nice :)
Once you start, things are tough. You need to move from your mainly research oriented work and start teaching, figuring out paperwork, policies etc. I am super lucky that @ZernikeInst tenure trackers are amazing, and always help new people. I always have people to ask advice
@ZernikeInst We work on solving problems together. And if no one has a solution for my problem, at least I can get moral support from them (and more senior colleagues) 😃 They are a really excellent group of people, and I am happy to have them, as otherwise it gets a bit lonely...
@ZernikeInst I also relatively often work evenings and weekends (today as well a bit). Sometimes it is due to paper deadlines 📰, but often it is simply a bad combination of teaching deadlines/preparing lectures and grant deadlines.
@ZernikeInst As I've mentioned before, it does take me 8h (on average) to prepare one lecture for the course I am teaching for the first time. This does go down A LOT second time you teach, so I am optimistic about my free time in the future 🤞
@ZernikeInst I also do think that we need to work on changing our academic culture when it come to this. We love our work, but we also have so many different roles we need to fulfill, that it is simply impossible to do within "normal" working hours https://t.co/1rTaFs5lJh
@ZernikeInst So sometimes you really need to decide what to prioritise - and also you need to see if there are thins you can delegate and optimise.
@ZernikeInst What do you think about this #AcademicTwitter ?
Btw, did you know it is #OpenAccess week next week? It is something I am really passionate about. I am lucky that we have some deals with publishers, so that my articles can be freely accessed (not always, unfortunately). But I also always try to have drafts on @arxiv 💜
There is still a lot of work needed to make open access better. Costs are high, and not everyone can afford it. I try to add some open access expenses in my grant applications as well, but it takes a lot of money...
I am also trying as of recently to publish our datasets related to published work, mainly on @ZENODO_ORG There's a lot of work on this, and getting all data to fulfill #FAIR principles in my field, which I think is great. But again, will take some time to implement well. https://t.co/txuR1EcjIQ
@goldclusters @CaboAntonija Glad you liked it!
Thank you Antonija for a fabulous week of science and opening a door to your day-to-day life as a scientist! Everyone, give @CaboAntonija a follow! @ZernikeInst @univgroningen @the_ScienceTalk Fancy tweeting from this account for a week? Tell us here - https://t.co/B53FjeXIb1 https://t.co/we1YJvjBOb
Chris Brewer
🛁🧩🛁🧩Molecular Puzzles in Chemical Bathtubs🛁🧩🛁🧩 Please welcome @DrCBrew for a week of puzzles in chemical bathtubs!🥳 Check out #UnderTheMicroscope episode ft. Chris w/ @svenja_lohmann 👇 @the_ScienceTalk @UTDMaterialsSci https://t.co/qEApDPcjzd
Fun fact, @DrCBrew & @McElweeWhite now have two things in common 1⃣ Their career paths crossed at @UF 2⃣ They both featured on #UnderTheMicroscope 🥳 Check out Lisa's episode 👇😊 @the_ScienceTalk @UFChemistry https://t.co/JOXZ7P9hjk
👋 Hi everyone! I'm @DrCBrew and I'm taking over this week to share a bit about what I am up to and have been up to. I'm currently a postdoc in the Walker group at @UTDMaterialsSci and we'll also be talking about the current work going on in the group!
I'll have more to share once its daytime in Dallas. I'll answer the most important question though... the chance of a Porkchop feature this week is non-zero. 😼
Who am I? Here's a brief run through this week's curator's academic history and the road to it! 🧵
My interest in science was really sparked while working at the Museum of Science and Industry (MOSI, @mositampa ) in Tampa from 2006 - 2015! Here's a few photos I could dig out from that many years back. https://t.co/o58aAGD0nV
At @mositampa I actually started my research career in education, working with a team of researchers on developing successful scaffolding strategies for informal education centers. (If you look closely in the photo, you'll see 16 year old me) https://t.co/fSwTRwVdr5
I received my BS in Chem and Biochem from Florida State University in 2014. I began to get my gloves wet working with Prof Lei Zhu (@ChemistryFsu) synthesizing bisazides for molecular linkers and developing methodology for synthesizing bistriazoles. https://t.co/7xkBJfWSIb
While at FSU, I also continued exploring my interest in education by doing demonstrations and outreach for @ChemistryFsu! (At one show I even had a chance to get the church cat involved!) https://t.co/lrFQ44StsE
I moved to University of Florida (@UFChemistry), where I worked with @McElweeWhite designing precursors for a few different deposition techniques, while also studying the decomposition pathways for the precursors. Here's photo-decomposition: https://t.co/AOixSXh9AH
I also designed molecules for focused electron beam induced deposition as well: https://t.co/82VAngLnnM
While at UF, I worked with @UFHonors to develop a Harry Potter themed Potions Camp (Potterology) for incoming freshmen into the Honors Program! It is interdisciplinary, so courses like Herbology are also included! I have had the pleasure of teaching this course 7 times. https://t.co/MPsxFN59Jj
In 2021, I graduated from UF with my PhD in Chemistry. In case you were curious, I did take graduation photos with my cat! https://t.co/NYx2SEIqMA
From 2021 - 2023, I was a Postdoc @NCStateChem, working with @CastellanoGroup designing organic chromophores for OLEDs! I developed a strategy for designing emitters with tunable properties. https://t.co/7pRxq2q7Rn
If you'd like to hear more about my chromophore design work, I'll be sharing the story at #AVS69 @AVS_Members
In September 2023 I moved to @UTDMaterialsSci to join the Walker Group and am now working on developing methods for depositing transition metal chalcogenides by Chemical Bath Deposition.
Stay tuned this week to see more about the work I have been up to as well as the rest of the work being done in the Walker lab! https://t.co/eJi1xVU1CM
One of the projects that we have going on in the lab is Photoassisted Chemical Vapor Deposition (PACVD). While I was a graduate student with @McElweeWhite, I also had the chance to travel to @UTDMaterialsSci to use the reactor with the precursors I synthesized! 🧵 https://t.co/P49Ieh8p22
While at @UFChemistry, my major contribution was to design the precursors and study their photo-decomposition pathways and quantum yields so that we can understand what makes a suitable precursor for PACVD.
Where I started on this process as a first year grad student was drawing designs for a setup and a phone call to Newport to place an order for an Hg(Xe) arc lamp. We've since upgraded the setup to use LEDs and a solar cell detector! (https://t.co/y5KYyFSh7i) https://t.co/hvz3TJPfZK
We setup a dark room to make it easier to run these experiments and characterize the samples. We called it the Red Light District! https://t.co/gQcUNA2b4M
If you'd like to read about the first set of compounds I studied, we published the work in Organometallics: https://t.co/OigCJ7ibzt
A fun fact though, the most effective way to synthesize some of my reference compounds ended up with me on the roof of the building using the sunlight as my light source! https://t.co/TxfYYZ7X34
Running reactions on the roof of the building did lead to some unique photo-ops for my reactions. https://t.co/6KwIPlafzD
We have also published the PACVD results from the (allyl)Ru(CO)3X series, which does show a dependence on the halide atom. https://t.co/eVZajLLb7F
The next series of compounds that I studied was a series of Ru(0) diene complexes. We have sorted out the photo-decomposition and PACVD experiments are underway! https://t.co/jsYOB9GqGD
Synthesis of the Ru(0) diene complexes was simplified by a custom built photoreactor from the @UFChemistry Machine and Electronics shops, with the ability to perform high intensity irradiations at multiple wavelengths! https://t.co/8gxVZKH1ro
Except for the cyclobutadiene complex, which insisted on liquid NH3 and Na. https://t.co/aVLoC3UnLh
Ru is not the only metal that we have looked at for PACVD. My colleague Hanwen investigated Pt precursors for PACVD: https://t.co/jbbWIZMfXX
A long story short though, we actually discovered that the Pt precursors did not require light, and instead we were able to deposit Pt by low temperature CVD. https://t.co/K1A9HECBWf
Which takes us back a little to the origins of the PACVD project, using trimethylaluminum for area selective, room temperature CVD. https://t.co/RYR6lHwnIx
UV light does enhance the deposition of Al at room temperature though. https://t.co/HErjLvVnSg
Which is where we got the idea to investigate photo-active Ru compounds for PACVD! https://t.co/AcMWgnQm5U
The substrates that we are using for these depositions are self-assembled monolayers on Au. We are using this as a model system for metallizing organic substrates. https://t.co/WszTt5Bfu1
If you've stuck with me this long, that is a brief history of the PACVD project I worked on as a grad student! Work is continuing with Bishwa, Rashmi, and Xin at UF. Kongkona is handling depositions at UTD, where sometimes I also have the chance to jump back in as well!
Data interpretation on this work was open to all paws! Porkchop found the molecular orbitals very interesting. Pictured is him sharing his thoughts on the orbitals during a Zoom call. He also prefers to have a front row seat while surfing the web for info. https://t.co/Lqrtt1Nass https://t.co/qBPuoKtYLB
For something a little different today, another project that we have going on in the lab is investigating model systems to better understand degradation pathways and restoration methods for lead-glazed ceramics. https://t.co/DhPlfaXdwv
Some of our studies are done on real ceramic artifacts like the one from the photo!
We use tools like XPS and Raman Spectroscopy to understand more about the composition of the materials.
Based on what we observe spectroscopically in the ceramics, we can develop model systems to test decomposition pathways and probe potential restoration methods before we try on the real ceramics. We've got a pretty bright outlook on the involvement of light in these processes! https://t.co/fBDzK3ePdP
This work is led by Ally, who also shared her work today at the Graduate Student Poster Competition! This work isn't published yet though, so Temoc wooshed in to hide everything except the title as I was taking the photo. https://t.co/jfa7yoJYm3
"Chemical Bathtubs", where did we get that title? Well, it comes from the technique I (@DrCBrew) use in my work, Chemical Bath Deposition (CBD) of transition metal chalcogenides.
In simple terms, CBD is a method for depositing a material onto a substrate by placing the substrate into a solution containing a mixture of chemical components. https://t.co/UdyuBuOHco
Like our other deposition project (PACVD), the substrates that I use here are self-assembled monolayers (SAMs) on Au, which are a model system for depositing onto other organic substrates. https://t.co/40GYOuMCjs
We use different functionalized SAMs to determine how a functional group influences the deposition of a material.
Functionalized SAMs also allow us to look at performing area selective deposition of our materials by using patterned SAMs.
The common components in a CBD bath are a metal source, a chalcogen source, and a complexing agent. Other properties of the bath (like pH) can also be tuned!
We do all of our depositions at room temperature. So we typically tune amounts/ concentrations of components, the components used, and pH. With this we can modify, the reaction pathways occuring, their kinetics, and some of the surface chemistry. (Likely over simplification!)
The deposits that we get from CBD are thick enough you can see them with your eye! https://t.co/dfw7ANtBjL
Our common initial characterization includes optical microscopy, Raman spectroscopy, and XPS. https://t.co/2ylTItKaMQ
My work is not published yet (I do talk a little bit about what I am doing in the podcast though!), but I can share a bit about some of the prior CBD work we have done in the lab.
Previous lab members done some work on CBD of MoS2 films in the past: https://t.co/YpB2e9dymE
For a look at area selective deposition of CuS by CBD, check out some of our previous lab member's work! https://t.co/gRMNOT4OCK
Depending on how you tune your bath pH, you can control the deposit between Cu2S and CuS! https://t.co/hKozU1UWiC
Hopefully you find chemical bathtubs as exciting as I do now! I'm looking forward to being able to share my work once it is ready
Nano science and a college level Harry Potter themed potions class! 🪄🔬 How did I mix the two to mix? https://t.co/hkrQwPzTyl
One of our experiments involved making tie dye t-shirts. Buying a kit would not be any fun though, so instead we make the dyes ourselves! https://t.co/5WkDq8zVlJ
We have three colors, blue, mauve, and red. So here is a little on how we make each of the dyes for the t-shirts. https://t.co/v85wwo1hDj
Mauve was the simplest to prepare, which we did by a quick oxidative coupling. https://t.co/mwGo4RNEWq
Red we prepared by extracting carminic acid from cochineal insect remains. This involved grinding them to a powder and then an extraction with boiling water and urea. https://t.co/LCtVjeSfmP
We prepared blue by making a Prussian blue nanoparticle ink! We started by precipitating and drying Prussian blue. The color of the powder is just beautiful! https://t.co/QnZTpWINpy
When mixed with sodium ferrocyanide, you can prepare a suspension of a nanoparticle ink with Prussian blue which will stick to our mordanted shirts! https://t.co/UogC56IMv4
Once we have synthesized our dyes, we add them to a squeeze bottle and apply them to our mordanted shirts. The dyes stick to the shirts quite well! The shirt that I am wearing in this week's profile photo has been washed several times since applying the dyes. https://t.co/HoZfh0ktFv
This was also not our only experiment involving Prussian blue. We made cyanotypes, where the light helped us generate the Prussian blue in the paper. Here are a couple examples of some of the ones the students made. https://t.co/DFuZEmRJAz
Stay tuned, I'll share more about Potterology before my account takeover ends!
How does a scientist spend a weekend? Well first, like any morning, it starts with my alarm clock waking me up. His name is Porkchop! 😼 https://t.co/kdycKyrBSR
It’s important that I open the blinds right away, because there are squirrels to hunt for! When it’s not an active hunting session, then it’s playtime. https://t.co/fVEQLzy8ix
While Porkchop is hunting, I’m able to watch Florida State play. Depending on the weekend, this may be accompanied by a Texas style pickle beer! 🍻 https://t.co/hJSmpmqF8l
When I’m not keeping up with the housework that Porkchop assigns me, I like to explore something new around the Dallas-Fort Worth area. Being new to the area, there is a lot for me to explore! https://t.co/ziCXYAoc3P
Downtown Dallas has a lot to see! So far I’ve enjoyed checking out Pioneer Plaza, I think my next trip downtown will be to go see the giant eyeball! https://t.co/ytTbfVSvnV
Fort Worth has a lot of charm! I enjoy making a trip over to check out the Water Gardens and Stockyard Station when I can! Making it in time for the cattle walk is a must! Next trip though, I want to explore Sundance Square. https://t.co/BNuBpoDVz0
One of my favorite things to do while exploring a new town though is check out the breweries. I have a wall with signs from some of my favorite breweries, some of the ones I’ve been to in Texas have already made the cut! https://t.co/5CvCEnFPTJ
With a last name like Brewer, of course I like to make my own beer from time to time as well! Here’s a photo from the last time I made my Smoked Dark Chocolate Pepper Stout! https://t.co/KiBLLm8SN5
Living in Texas I’m also a fan of smoked meats. So I do also enjoy firing up the smoker! I make pork more often than brisket, but I’m sure that Texas will convert me. https://t.co/X9eVw0Yvl5
Every now and then I like to spend my weekend traveling. I really enjoy seeing new things and new places! Living near DFW makes it convenient to get to new places. https://t.co/zdBhFhs5oM
Most importantly though, Porkchop is very good at reminding me to use some of my weekend time to get some rest. https://t.co/EPVevlouGo
One more experiment from Potterology before I sign off for the week, this time I'll share about our Lumos experiment! https://t.co/zTCLTxyQFk
Being an organic chemist by training, I slipped a little bit of organic synthesis into the course and had the students synthesize "TCPO" as one of their experiments. https://t.co/vJcGJkYBTa
TCPO is a derivative of the active ingredient used in commercial glowsticks. We activated our Lumos spell by mixing it with a chromophore and hydrogen peroxide! This experiment is always a class favorite! https://t.co/Fbf6PmWCmo
We used perylene as our chromophore because it is relatively affordable, bright, and most importantly... it worked! https://t.co/NSDL86b16w
Keeping with the magic theme, we also had the students make Eu smash glow crystals! These crystals emit light by triboluminescence as you grind them with a spatula. The Lumos and smash glow crystal experiments were actually inspired by @NurdRage videos I watched many years ago https://t.co/oimoAx4zFp
If you'd like to see more about Potterology, check out this thread from when I led the program in 2022! https://t.co/PgeDFztMDC
The week is about over, so I think this about closes out my curation of Real Scientists Nano! Thank you for having me, I have enjoyed sharing some of my work and my labmate's work over the last week! https://t.co/Fdtuwf9knt
I hope you enjoyed the photos that I was able to dig up over the week to go along with the experiments. Long story short, I am trained as an organic chemist, but have been slowly transitioning over to the materials science world! https://t.co/dRhpbO72om
I hope to have more work to share soon! For now, I'm @DrCBrew and this has been enjoyable!
Thank you Chris for a smashing week of science! Everyone, give @DrCBrew a follow🥳 Do you want to take over this account? Tell us here - https://t.co/NeHnkiQCQN @the_ScienceTalk #UnderTheMicroscope @svenja_lohmann @UTDMaterialsSci https://t.co/ZoSDlbcsAT
Ketan Madane
🌊✨🫧🌊✨🫧 the MAGIC of Flows 🌊✨🫧🌊✨🫧 Please welcome this week's curator @Ketanmadane 🥳 Check out the conversation between Ketan and @svenja_lohmann 👇 @the_ScienceTalk @UL https://t.co/H7x9mZJ4sr
@SodeAndy @taylordsparks @GemmaCSolomon @jensengroup_cph @kirsten_mj Congratulations 🙌
As the curator for @RealSci_Nano, this week I'm thrilled to kick off our journey with a glimpse into the cutting-edge realm of Multiphase Reactors and Intensification! @BernalNews @UL 🚀 Follow this thread as we delve into our group's area of research #MRInG ✨ 1/5
𝐌𝐮𝐥𝐭𝐢𝐩𝐡𝐚𝐬𝐞 𝐑𝐞𝐚𝐜𝐭𝐨𝐫𝐬 𝐚𝐧𝐝 𝐈𝐧𝐭𝐞𝐧𝐬𝐢𝐟𝐢𝐜𝐚𝐭𝐢𝐨𝐧 𝐆𝐫𝐨𝐮𝐩 (MRInG) - uses experiments, computational flow modeling, population balance models machine learning to generate new insights into multiphase flows, reactors, and process intensification. 2/5 https://t.co/1aGVcdWQiX
Contributions in reactor scale-up, performance enhancement, and intensification result in resource conservation, decarbonization, mitigation, and valorization of waste (prosperity of planet) 3/5
Contributions in MAGIC processes, mixing, emulsions, crystallization, and quality by design result in better health care and nutrition, improved lifestyle, overall well-being, and personalized products (prosperity of people). 4/5 https://t.co/HtRMuxArpe
Visit our research hub at https://t.co/hjWz0hftss to explore the groundbreaking work by MRInG. 🌐 Stay tuned throughout the week for intriguing insights as we share latest highlights from our dynamic research group🧪📊 #MRInGInnovates #SustainableTech #MAGICProcesses 🌐🔬✨ 5/5
One device that I work on in my PhD at 𝐌𝐮𝐥𝐭𝐢𝐩𝐡𝐚𝐬𝐞 𝐫𝐞𝐚𝐜𝐭𝐨𝐫𝐬 𝐚𝐧𝐝 𝐢𝐧𝐭𝐞𝐧𝐬𝐢𝐟𝐢𝐜𝐚𝐭𝐢𝐨𝐧 𝐠𝐫𝐨𝐮𝐩 @BernalNews @SSPCentre @UL is 𝐅𝐥𝐮𝐢𝐝𝐢𝐜 𝐎𝐬𝐜𝐢𝐥𝐥𝐚𝐭𝐨𝐫. Ever heard of 𝐅𝐥𝐮𝐢𝐝𝐢𝐜 𝐎𝐬𝐜𝐢𝐥𝐥𝐚𝐭𝐨𝐫🤔Buckle up! 🚀#FluidicOscillator
1/ 💡 Ever delved into the intricacies of Fluidic Oscillators? Prepare for a deep dive! These devices harness fluid dynamics, utilizing precisely designed channels and nozzles to induce oscillatory motion, all without conventional moving parts! 🔄🔬#FluidDynamics https://t.co/XgpSBvENju
2/ 🌪️Fluidic Oscillators exploit the Coanda effect and entrainment phenomena. By manipulating fluid flow rates and pressures, engineers control vortices, generating stable oscillations. It's an elegant dance of forces and velocities in fluid mechanics! 🌪️💫 @ANSYS https://t.co/KiqECAfSY8
3/✨Building upon our profound understanding of Fluidic Oscillators, our team ventured into the realm of practical applications. 🛠️ One such groundbreaking application lies in the realm of continuous crystallization. #InnovationInCrystallization
4/💎By harnessing the unique characteristics of Fluidic Oscillators, we've improved crystallization processes. These oscillators enable precise control over Particle size distribution. More about this in a separate thread🌟#CrystalEngineering #ContinuousCrystallization
Ever wondered what a day in the life of a PhD student? Join @Ketanmadane as he takes through a day in his life @UL @sspcenter in Ireland! 🧪📚 #PhDLife #DayInAScientistLife 🌐🔬✨ 📚🔬 #dayinascientistlife Shot on @GoPro https://t.co/cROhzDuPSK
10 PhD positions up for grabs!🌊Exciting News in Cavitation Research! Introducing the CaviPRO ITN Project, a revolutionary initiative set to transform hydrodynamic cavitation into a game-changing force for industrial processes. 🔬🔄 Follow this thread for more! #PhDOpportunity
🌐 Project Overview:Hydrodynamic cavitation poses challenges, but CaviPRO aims to turn them into opportunities. From controlled cavitation to additive manufacturing, advanced process control, and machine learning, we're diving into uncharted territories.
🤝 CaviPRO Consortium:Our international dream team includes experts from Ireland, Germany, France, Italy, Slovenia, and Switzerland. Together, we're on a mission to harness cavitation for economic growth, innovation, and leadership in the field
🎓 PhD Positions:📆 Starting July 1st, 2024 🌐 10 positions available 📝 Application deadline: January 5th, 2024 🔗 Details and how to apply: CaviPRO@ul.ie CFD Online - CFD Jobs Database - Job Record #18823 (https://t.co/VRIl9fBSqO)
🔍 Eligibility Criteria:Candidates, ensure you meet the MSCA-DN mobility clause, haven't held a doctoral degree, and are eligible to work in your host country and other European nations for secondments and meetings.
📋 Selection Process:Applications are welcome until January 5th, 2024. Follow OTM and competency-based recruitment principles. Be ready to provide a comprehensive application, including a motivation letter, CV, references, and preferred institutions.
🚨 Note: Your application may be shared with consortium partners, and the deadline could be subject to extension.
Join us on this groundbreaking journey! 🌍✨ #CaviPRO #CavitationResearch #PhDOpportunity #InnovationInScience #ApplyNow #FutureResearchers 🌊🔬
💡 The Million-Dollar Conundrum in #FluidDynamics! 💰✨ The #ClayMathematicsInstitute has issued a $1 million challenge – solve the Navier-Stokes existence and smoothness problem. 🌊🔍 Join me on this thread to know more.
N-S you beauty: At the heart of fluid dynamics lies the Navier-Stokes equations, governing the motion of fluids. These equations are derivatives of basic laws of #physics viz. Mass conservation and Newton's Second law applied to Fluid Flow https://t.co/veHn4E3jk1
The Clay Institute's problem revolves around proving the existence and smoothness of solutions to these equations. While solutions are available in limited cases, a universal understanding remains elusive. This challenge stands as one of the seven problems.
💰 A $1 million reward awaits anyone who cracks the code! Mathematicians worldwide are drawn to the challenge, making it a pinnacle of mathematical exploration.
One interesting thing about N-S is even #StringTheory arrives at NS in a certain sense.
🧩 Why is it challenging? The Navier-Stokes problem is tricky due to its nonlinearity and #chaotic behavior. Tagging @numberphile video on NS for a simple but better understanding of this beautiful equation.https://t.co/Q7yuuqFZiM
🌪️ 𝐕𝐨𝐫𝐭𝐞𝐱-𝐁𝐚𝐬𝐞𝐝 𝐂𝐚𝐯𝐢𝐭𝐚𝐭𝐢𝐨𝐧 𝐃𝐞𝐯𝐢𝐜𝐞𝐬💡a cutting- edge technology with potential to revolutionize various industries. We at 𝐌𝐮𝐥𝐭𝐢𝐩𝐡𝐚𝐬𝐞 𝐫𝐞𝐚𝐜𝐭𝐨𝐫𝐬 𝐚𝐧𝐝 𝐢𝐧𝐭𝐞𝐧𝐬𝐢𝐟𝐢𝐜𝐚𝐭𝐢𝐨𝐧 𝐠𝐫𝐨𝐮𝐩 @BernalNews @SSPCentre @UL @ChemicalSciUL https://t.co/FkoCgITiGO
Vortex-based #cavitation involves the controlled formation and implosion of tiny bubbles in a fluid, creating powerful shockwaves. This phenomenon is harnessed to enhance processes like #mixing, #reactions, #emulsions, and #crystallization. https://t.co/qOmjtm4gzt
Unlike traditional #cavitation, where the collapse of bubbles can be destructive, vortex-based devices leverage controlled cavitation. The result? Enhanced mixing efficiency, accelerated reactions, and improved performance in various applications.https://t.co/A0qI6yYuDS
From chemical processing to wastewater treatment, vortex-based cavitation devices hold promise in diverse fields. These devices can optimize energy transfer, reduce resource consumption, and improve overall process efficiency.https://t.co/B5s8ccqNHR https://t.co/QiOohvikzG
@VORTA_TECH is a company that uses such a Vortex-based #cavitation for a variety of applications more about them in a separate thread. https://t.co/LgStnG0rp7
Crystallization is a process widely used for purification and synthesis of drugs and biomolecules in the pharmaceutical industry. The critical quality attributes (CQA) of the crystals help us decide whether the crystals produced are fit for our application or not. 💎✨
Along with purity, polymorphic form, shape of the crystal, and particle size is an important CQA. The crystals formed are not all of the same size and hence we refer to the distribution of the sizes as the particle size distribution (PSD). https://t.co/dNo8o1K7FK
One of the major goals in the pharmaceutical industry is to achieve a uniform particle size. We need to incorporate tools that help us monitor the process while it is happening👩🔬These tools are referred to as PAT tools or process analytical tech tools.
The focused beam reflectance measurement (FBRM) is one such PAT tool that uses the measurement of the reflectance of a laser beam off the surface of the particles as an indicator of the size and number of particles. 🔦⚡https://t.co/kzVxgiOn7u
The FBRM measures the length of a random chord (CLD) on the particles and not the actual size. The inversion of CLD to PSD for spherical particles has been discussed before. https://t.co/kT4O5C06kD
While everything would seem easy-peasy with the instrument telling us the size of our particles as we are crystallizing them, it is unfortunately not so easy for irregular-shaped particles. https://t.co/U1zFcMBmej
At MRing @VyshnvyH has developed a mathematical model that helps us convert the CLD of needle-like particles to its corresponding PSD. These models are applicable in the case of irregular particles as well as to systems described by bimodal PSDs. @SSPCentre @ChemicalSciUL https://t.co/9oOBQVoPkK
Festschrift Issue in Honor of Professor Vivek V. Ranade @RanadeVivekV is out! https://t.co/pfUsilD2mD Prof Vivek Ranade is Bernal Chair of Process Engineering at the University of Limerick, Ireland. @SSPCentre @BernalNews @ChemicalSciUL @UL https://t.co/1OF7yfVMIC
Preface for Festschrift Issue in Honor of Professor Vivek V. Ranade written by Prof. Ashwin W Patwardhan https://t.co/l0bfgh50PX
MRInG member @jagdeepn220 is associated with Project #ValiD - 'Valorisation of Digestate using Photocatalysis and Hydrodynamic Cavitation' under the guidance of Dr. @RanadeVivekV Collaborating with Dr. @ProfMNCollins (@UL), Dr. Peter Robertson (QUB), n Dr. Denis McCrudden (ATU) https://t.co/Y0Na4YTADZ
Along with industrial partners Green Generation Ltd, Biocore, and Renewables United Ltd.♻️ Join us on this innovation journey towards a sustainable and circular economy🚀#GreenInnovation #CircularEconomy🌐#Sustainability @UL_Research @agriculture_ie @BernalNews @QUBelfast @atu_ie https://t.co/ar2EWp4BJs
RT @mhdguimaraes: This week we had the fantastic @MySci_PK visiting us at @ZernikeInst. She showed us her trajectory as a science communica…
Can we alter or control the particle size distribution of forming crystals using fluidic devices? In the following research 4 fluidic devices were used to study their effect on the forming particle size distribution of #Paracetamol #Particlesizedistribution
https://t.co/MUFdaryFdY
Configuration 1 (STR): Conventional stirred tank with the addition of anti-solvent in the tank Configuration 2 (STR+PRC): Stirred tank with external recirculation loop and addition of anti-solvent in the recirculation loop (after the pump)
Configuration 3 (STR+FO): Stirred tank with external loop through FO and addition of anti-solvent just before FO Configuration 4 (STR+VD): Stirred tank with external loop through VD and addition of anti-solvent just before VD
There was a visible change in the particle size distribution with the usage of fluidic devices. https://t.co/CbUILzkj1g
What an incredible journey curating this account has been! A massive shoutout to the amazing @svenja_lohmann n @MySci_PK. This is @Ketanmadane, officially signing off with a burst of gratitude! Special mention to my Supervisor @RanadeVivekV #CuratorChronicles #FarewellFabulous
RT @Ana_Mikheenkova: Last Friday I nailed (literally) my dissertation called “Investigating ageing mechanisms in electric vehicle #batterie…
What a week it has been! Thank you @Ketanmadane for a smashing week of science!👏 Everyone, do give Ketan a follow🥳 Do you want to take over this account for a week? Tell us here - https://t.co/BoXJeeNOld https://t.co/JNBhPrCo3H
Sofia Ferreira Teixeira
"Faster phones, thanks to SPINTRONICS" Please welcome the amazing @DrSofia_F_T for a week of science behind the tech of the future which will make our electronics faster🥳 @nanoGUNE @the_ScienceTalk Check out the conversation b/w Sofia & @MySci_PK 👇 https://t.co/qWC8cN3Tzq
Hi everyone! I am @DrSofia_F_T and I am currently a postdoctoral researcher @nanoGUNE! I am thrilled to be taking over this week to show you all about what I do and have done over the years! It will be a healthy mix of science, hobbies and most likely cats. Stay tuned!
So, who am I? My name is Sofia Ferreira Teixeira, and I am originally from Portugal. I am a #physicist, besides being a crazy cat lady and loving music a bit too much. So, how did I end up here? A🧵
It all started in 2011, with the Summer School of Physics @UPorto @ciencias_fcup for high school students. It was a week full of lectures and in the Physics Department labs, where I felt at home. We also had a project that we presented (see photo!) It was an amazing experience! https://t.co/CzXiBZPmzA
@UPorto @ciencias_fcup Having discovered my love for Physics that week, I decided to do a BSc in Physics @UPorto @ciencias_fcup. During the 3 years, I learnt I love experimental work! I also enjoyed my time as a uni student, with a bunch of traditions, like the "traje" we are wearing in the photo! https://t.co/siftKKjMUs
@MySci_PK @UPorto @ciencias_fcup Yes! The project was called "Nanoparticles for medicine" and the idea was to use carbon nanotubes to carry certain drugs. We spent the whole week doing these nanotubes and it was awesome!
A brief pause on showing how I got here, because today is a very special day at my group @CICNanodevices @nanoGUNE: we will have a new doctor! Isabel is defending today her PhD on topological insulators and Spintronics devices! 🥳🥳 https://t.co/ZkollabfHe
Tune in later today to find out more about what these topological insulators are and why they are interesting for Spintronics ;)
During my time as a student, I had several opportunities to know different fields of physics and how research is, which made me want to do science. One of them was my time as a @CERN Summer Student! It was a fantastic time, full of experiments and experiences! https://t.co/HNlLVFHZh6
@CERN Another opportunity was the internships offered by @ciencias_fcup. I did 3 internships on the same topic: thermoelectric effect! I loved the topic and enjoyed working with my supervisor and his team at IFIMUP! It also gave me the chance to present at conferences for the 1st time! https://t.co/sR9SoxOFGf
Realising I wanted to do research and that I loved experimental work, I did a MSc in Physics @UPorto @ciencias_fcup and IFIMUP, focusing on material physics. My thesis was about electronic properties of topological insulator thin films! It envolved a lot of fun clean room days😆 https://t.co/WyikoQdeyn
I started my PhD in 2018, studying the magnetic and electric properties of topological insulator/ferromagnetic nanostructures. During my 2nd year, I spent 6 months @imperialcollege, measuring samples, learning from my colleagues and having this view from the Physics common room! https://t.co/HGLH8I209L
At the end of March 2022, I defended my PhD in Physics. It took me just over 3 hours but eventually I was indeed called a Dr! The defense was still hybrid: some of the jury was online, but in the audience I had my family and friends, which made the moment that more special! https://t.co/kff6mtdnFf
And here I am now: a postdoc @nanoGUNE in the @CICNanodevices group! I now work on Van der Waals materials and heterostructures towards novel (spintronics) devices. It continues to envolve a lot of clean room time and experiments! And this week I will show you some of it!
Good morning! Tuesday mornings for me mean a subgroup meeting! 👩🏫 My colleagues and I share what we did the week before and discuss the latest measurements or any problem we found!
Now that you know how I got here, you may be asking what is or was my work. 🔬 👩🔬 Well, if you already listened to the podcast, you may already know, but here is an overview of it😉
Nowadays, @nanoGUNE, I work with van der Waals (vdW) materials. Have you heard of graphene?✏️Well, it is a vdW material, but since its "exfoliation" (remember this word) a lot of other materials like it have appeared, from magnets, like the ones on the fridge, to superconductors!
@nanoGUNE But now you ask me, well but why do you care about them? What is so special about these materials? And what do you do with them?🤔
And while I let you think about why we care about vdW materials 😉, it is time for a Basque (Euskera) class at @nanoGUNE! Euskera is spoken here in the Basque Country, and the classes are always a fun break to learn and discover more about the region! https://t.co/B3o6aS5kFh
The vdW materials have a wide range of applications due to some extraordinary properties! 💫 They are made up of layers connected by these vdW forces, which are very weak. Thus, one fantastic property is that we can separate the layers, aka exfoliate, and get very thin flakes!
In a magnetic vdW material, we can play with its magnetism: we can go from a ferromagnet, like the fridge ones, to different magnetic phases like antiferromagnet 🧲 We can also end up with different magnetic orientations, called anisotropies, which we look for in certain things!
@nanoGUNE I am exploring the magnetic and transport properties of these vdW magnets, also called layered magnetic materials.🔎 We study how they behave when we apply magnetic or electric fields and then we try to tune and control their behaviour! 🔧🎮
@nanoGUNE And one of the reasons for doing all of this is to create novel Spintronics devices! Listen to the podcast to hear me explain what this thing called Spintronics is, but in a very simple way Spintronics=spin+electronics It is using the spin like we use the charge of electrons!
@nanoGUNE Due to the vdW forces magic 🪄 we create these devices like we play with Legos: we stack one vdW material on top of another! 🧱 So we can combine a vdW magnet with another vdW material that, by generating a spin current, controls its magnetism! The possibilities are endless!
@nanoGUNE So, some days this is me! (With tiny flakes and in a clean room suit but an accurate representation 😅) https://t.co/OmSeNrsOC0
I showed you how I play with legos, aka build nanostructures of van der Waals materials, and study the magnetic and electronic properties of these. But, how do we fabricate these materials to be able to explore their properties? Come with me and let's fabricate a device!🧵
It all starts with a bulk crystal! 🪨 This is a piece of material that is macroscopic that we can hold in our hands. But it is made up of thousands and thousands of layers connected by vdW forces, so if we want just a few layers, what do we do? We exfoliate with scotch tape!
Yes, you read that right! We put the crystal between two pieces of a special scotch tape and we seperate them. This separates the layers of the material. And if we keep going and going we can reach very thin flakes, aka pieces of the material with very few layers!🤏
Sometimes these materials don't like being in normal air conditions, too much oxygen and water for their liking🌬️💧 for these we exfoliate inside a Glovebox: a box where the air is controlled to minimise O2 and H2O that we access with gloves (the name is very apt isn't it?)
So, now we have our thin flakes on the scotch tape, but how do we study it? We need to transfer the material onto a substrate where we can then do all we need. We mostly use silicon substrates with an oxidized layer, aka Si/SiO2. This is what it looks like! https://t.co/ebxnGHN4SS
We end up with many flakes on the substrate and now comes the best part for some, the worst for others: we need to search and choose the flake we want to study! For that, we use a simple optical microscope🔬and take a📸! What do you think, would you like to search for flakes?
We now have our flake!🥳But how do we measure its electronic properties? We need to contact the flake with electrical contacts! We use a metal, like Gold or Platinum . But before we use up our Gold, we have to do the part I like the most: design the contacts! ✍️
For this we use a method called Lithography, which comes from Greek and means writing in stone✍️🪨But if you draw by hand, your design is too big! So we use something else to write: light🔦and if we really want to go small, we even use electrons⚡️!
This is because the wavelength of light or of electrons is small enough that we can write micro or nanometric things〰️! And this is precisely the size we need for the contacts to our flake! But now you are thinking, if we are "writing" with light, what is our paper (or stone)?📜
Light sensitive polymers and we call them photoresists! We put a resist layer on the substrate with our flake and then we shine with light to draw our design. If it is a➕resist, the area iluminated can be removed, but with➖resist, this area stays and everything else goes away!
Here @nanoGUNE we can do it with light in a machine we call the Laser Writer (because it uses an UV light laser) 🔦 or we can use an eBL, which stands for electron beam lithography ⚡️, and uses an electron gun to write our devices!
@nanoGUNE Here is an example! You see on the left our flakes on the substrate, and we want to study the thin blueish one, marked with the green line. And on the right, you see the result after we do the lithography and we develop (yes! like an old photographic film) the resist! https://t.co/YOGnhB2EwH
@nanoGUNE On the right, the green area and the very big flake are still covered with the resist. In the purple area, the resist has gone away and we are left with holes, that we can fill with gold and thus contact and measure the sample!
@nanoGUNE We have our device almost fabricated, only two steps to go! We need to fill the opened resist holes with Gold. For that we deposit a thin film of gold or platinum, with a nanometric thickness, so also very small😉
@nanoGUNE We can use an Evaporator: we heat the gold to make it evaporate and it forms a film. Or we use a sputtering: we have a target of platinum at which we throw Argon ions so fast that some platinum is removed and is deposited! Here is a GIF of some sputtering I did in my PhD! https://t.co/4hvlcq9vdy
@nanoGUNE Almost there! Now we have or metal on the holes contacting the flake but also on top of the rest of the substrate that had the resist. So, how are we just left with the contacts? Well, we do what we call a lift-off 🏋️and we remove the resist, and thus also the metal on top!
@nanoGUNE This is the most nerve wracking step for me. After so many steps and effort, everything can be destroyed by a simple bad lift-off! But have no fear! We place our device in acetone and it worked! We get all the resist away and we are left with a nice contacted flake, our device!🥳 https://t.co/UffqDbJ0LQ
RT @DrSofia_F_T: Halfway there with the fabrication! We already see some drawn contacts! 👀👀 @nanoGUNE @RealSci_Nano
RT @DrSofia_F_T: A GIF done by chance on a clean room "boring" day! And it is one of the things I have used most in my presentations, from…
RT @DrSofia_F_T: And the final device, isn't it cute? Or is it just me that finds it cute? @nanoGUNE @RealSci_Nano
Having our device all ready, we can meaure it⚡️but not yet! This week, I managed to get a booking only on the weekend, since our measurement system is loved by everyone🥲, aka heavily used! The life of a scientist: a Saturday can be a Monday and a Monday a Saturday 📅🔁📆
So what am I doing today? Well, first catching up on some literature and reading some papers for my upcoming measurements! So this is me this morning! 📄👀 https://t.co/Ou3d61CbKF
Measuring days and I was mia for them. You plan your best but something happens and you need to adapt to what your sample wants to do, which can be just "I do not want to be measured" 🥲 But don't lose all hope, I am measuring and will take you through it! A thread 🧵😊
If you remember, we had our devices, contacted with metal and all ready to be measured. 🥳 Well, what do we actually want to measure here? 🤔
This material is a magnetic semiconductor, so we can explore its magnetic properties through measurements of its electric resistance and its dependence on temperature 🌡️, magnetic fields 🧲 (Magnetoresistance) or electric fields ⚡️ (Gate dependence)
We know what we want to measure, so let's get our device ready! We have to connect the metal that is on our flake to all the cables, to apply electric currents and measure voltages. We use a wire bonder: we connect our device with small wires of Gold or Aluminium to a puck! 🪡
This is what it looks like! I have 2 substrates, the shiny squares each with one device. You can see the squares of gold (or pink in the bottom one, do you know why they have different colours?), the tiny wires connected to them and the gold rectangles on the green puck! https://t.co/vABvME7scO
And here is a zoom into the puck, with other devices I have measured bonded. You can see how the tiny wires go from the Gold rectangles in the puck to the Gold pads of our devices! 🟨🪡🟪 https://t.co/dkxUYhaUuJ
Depending on the size of nanometric Gold, its colour changes! In this case the thickness of the metallic thin film is different, the pinkish squares are around 15 nm whereas the other ones are almost 50 nm!
Devices are ready to be measured! And we do this in a PPMS: a Physical Properties Measurement System! And yes, you read that right, a lot of the physical properties of materials can be measured in these systems, from optical, to thermal, to electrical as in our case!
They are super cool machines because we can measure things at temperatures all the way down to 2K and with magnetic fields up to 9T! And this is what one of our systems looks like at @nanoGUNE! To me it looks like a tiny space ship🚀, what do you think? https://t.co/R9zoi0O73b
@nanoGUNE Our device goes inside and, if the gods of the labs shine upon us, we can measure it and acquire a lot of data that we analyse to understand our materials! So, that is also what I end up doing in days when there is no lab work: a lot of fun with spreadsheets! 📊 https://t.co/PVPbROaHiT
@nanoGUNE Aka, this is what I will be doing next week with the data of this weekend😉 https://t.co/8A2g1wD55v
So, this week (and weekend) was mostly focused on work... But a life of a scientist is not only work, and as I promised, and as you heard on the podcast (if not, go on and give a listen to it!), here are other things that keep me "busy" on my free time 😌
I was and still am greatly involved in physics associations and societies! It all started with @PhysikUP, the Society of Physics Students @UPorto @ciencias_fcup! I founded it back in 2017 and it was amazing! They are still going stronger than ever, which just makes my heart full!
@PhysikUP @UPorto @ciencias_fcup After @PhysikUP, I became very active in @IAPS_physics, the International Association of Physics Students, becoming first their Events Manager and then their Vice-president and PR Manager! If you are a physics student, join them, it offers amazing opportunities!
@PhysikUP @UPorto @ciencias_fcup @IAPS_physics @iaps_physics does amazing things and gave me invaluable experience that I still use to this day! And they also organise cool stuff like iaps2CERN, which I got to organise at the start of my PhD in 2018! Here is part of the participants down in the LHCb pit! https://t.co/YyIWdqINLW
@PhysikUP @UPorto @ciencias_fcup @IAPS_physics Having graduated as a student, I am still involved in these activities! I have recently joined the Executive Board of @EmaMagnetism as their Young Officer, to work towards building and strengthening the community of students and early career members in the magnetism world! 🧲🤝
@PhysikUP @UPorto @ciencias_fcup @IAPS_physics @EmaMagnetism And I actively try to promote science and physics to everyone, through Outreach activities, or through the Gender Equality Committee of @nanoGUNE ! This work is extremely rewarding and always makes me feel super motivates to carry on going to the lab (even on weekends!)
@PhysikUP @UPorto @ciencias_fcup @IAPS_physics @EmaMagnetism @nanoGUNE And besides all of this, as promised, here is the mising cat tweet! This is my fantastic 16 year old Pucca! She does try to analyse some data with me sometimes and sympathises when experiments do not work, but she is also the best nap companion ever! However, she hates photos! 😆 https://t.co/i4u4hni7KB
And this week is almost over and my time as the curator is finishing! Thank you for having me and I hope you enjoyed as much as I did bringing you to the lab with me! 🔬 👩🔬🧑🔬👨🔬 https://t.co/2o6FfKWexR
I hope you had fun seeing my path and understood a bit of what my work is, besides having a sneak peek at my day to day life as a postdoc researcher! If you want to know more and keep the conversation going, you can find me @drsofia_F_T😊👋
@DrSofia_F_T And I leave you with a last cat gif! This was fun! 😊 Goodbye everyone! 👋 https://t.co/TmNyOV2TbL
Thank you Sofia for a smashing week of spintronics and your life as a scientist at @nanoGUNE😍 Everyone, give @DrSofia_F_T a follow!🥳 Do YOU want to take over this account for a week? Tell us here - https://t.co/pVUEntDaRo @the_ScienceTalk #UnderTheMicroscope https://t.co/IILmdGsAyQ
Amber Lim
"Crystals, Comics, Calculations, Chemistry" Welcome the LAST curator of 2023 - @xamberlim of @Fredrickson_UW @UWMadisonChem Check out the wonderful conversation between Amber and @mysci_pk to know what is coming your way this week! @the_ScienceTalk https://t.co/2HB8z1l3LG
Hello! I’m @xamberlim, and I will be your guest scientist this week! I’m a chemistry PhD student in the @Fredrickson_UW group at @UWMadisonChem by day, and also an art-loving, D&D-playing nerd 24/7! This week I’m going to cover 💎Crystals! 👩🎨 Comics! & 💻 Calculations!
💎 Crystals! I study intermetallic solid state chemistry. In molecular chemistry, the kinds of chemicals we study are often smaller, singular units. In solid state chemistry, our chemicals are linked together in one large unit that extends beyond the atomic scale.
This is one aspect that makes it challenging to research the solid state. Not only do we need to consider local effects around individual atoms, but also consider long-range or bulk effects.
Crystals are one type of solid. In science, we describe crystals with a unit cell, which gives us information about how atoms are arranged. These unit cells repeat in 3-D space, very much like a 3-D wallpaper. (Comic excerpt from our group website: https://t.co/l6eUWuWDGK) https://t.co/5zr9h3Ja5n
I study intermetallic crystals because metals are so diverse! Metal atoms can have varying sizes, electron counts, and electronegativities. As a result, when metal elements come together to form a new intermetallic compound, the bonds between them can have different characters!
This diversity of bonding in solids can be understood with the van Arkel-Ketalaar Triangle, which shows that bonding is a spectrum rather than a fixed types. https://t.co/THOLpjGL1d
Intermetallic materials can have bonds that have a mixture of these characters. My job and my passion is to understand the complex bonding in these types of materials, and I do that mainly through computational chemistry. https://t.co/3yvrsyz8UO
Of course, there's experimental aspects in this field of work too! I used to do experiments as an undergraduate researcher, but I have since turned my focus to pure computational work. I do miss getting pretty crystals though! (CuP2 below) https://t.co/14XmYiCNcG
Stay tuned this week to learn how I tackle these problems!
One perspective our group uses to study the formation of intermetallic materials is through the lens of FAST: Frustrated and Allowed Structural Transitions. 🚌💨 Before we talk about FAST, let's dive into some background...
There are three different factors we use to understand why solid state materials form: (1) Atomic size effects (2) Electronic structure (3) Electronegativity These are often called Hume-Rothery factors. In my research, I will focus on the first two factors! https://t.co/0t9kOycXfk
Atomic size effects: One way to think of our materials is to think of them as hard spheres in a box. A lot of metallic elements pack in certain patterns (hcp, bcc, fcc). If you’ve seen produce in pyramids at the grocery store, you may be familiar with these ordered packings. https://t.co/Xw1dezaHUR
When the atoms are different sizes, however, the problem of filling up space in an ordered way becomes more complex, as we can see in this holiday-themed example. 🎄 https://t.co/9jwUyUYJ1D
Electronic structure: A core part of chemistry is understanding how electrons interact with each other and nuclei. We have so many electron-counting concepts in chemistry (such as the octet rule and formal charges for Lewis dot structures) to rationalize structure.
In the field of solid state chemistry, we have many models and electron-counting principles as well, including but not limited to the Zintl concept, the Mott-Jones model, and Wade-Mingos rules. https://t.co/iofeU67s8G
These fundamental principles help us to determine whether systems are "electronically favorable" based on whether they ✅ perfectly satisfy the rules, 🆗 are very close to meeting them, or ⛔ don't fit at all.
Lastly, Electronegativity! This is the tendency of an element to attract electrons. Electronegativity is intertwined with electronic structure because differences in electronegativity can lead to different kinds of bonding (see the van Arkel-Ketalaar triangle in the last thread).
We tie these concepts together with the FAST principle. Overall structural stability can be viewed as a combination of these factors. When atomic packing conditions and the electronic structure are both favorable, the crystal structure will easily form. 👍 + 👍 = 👍
When these factors disagree, the crystal structure will be harder to form. In fact, we may see some ✨interesting, more complex structures✨ (such as intergrowths and modulated structures) as the factors compete on a local and global level. 👍 + 👎 = ⁉😱⁉
For an introduction to the FAST concept and a cool, modulated structure, check out this paper by my former colleague! It's a long one, but it's a good one! https://t.co/btYfkZzCnB
Tomorrow, I'll talk more about my specific research project. 👋😉 Signing off for today.
Good moo-rning, science enthusiasts! It's a crisp, chilly day in Madison! Here is one of my desk companions. Later today, I'll be talking more about my specific project. Look forward to that! https://t.co/XZGhNtbhut
@CycleFunMtl Cousins!! I love your desk companion as well!
RT @CycleFunMtl: @RealSci_Nano Moo! https://t.co/bbcpfXxxEZ
Today, I’ll give an overview of my specific project: ✨ 18-n+m isomerism in T-E intermetallics✨ Whoa, what a mouthful! 💦 Isomerism? 18-n+m? What does that mean?
Yesterday, I talked about electron-counting rules in chemistry, each useful in specific contexts and bonding. https://t.co/m6wt5zDf3Z
One domain of bonding we’re interested in is when compounds have both metallic and covalent characteristics. Transition metal (T) - main group metal (E) intermetallics are perfect candidates for this investigation, and furthermore, there's some interesting structural trends...! https://t.co/avXZIBXmKL
T-T connectivity in the crystal structure can be related to its electron count. We call this concept the 18-n+m rule, though it's also known in one of its forms as the 18-n rule. How does this rule work? We know that closed-shell compounds are electronically stable. https://t.co/zrVabk6hRp
Transition metal atoms can achieve closed-shell stability with multi-center T-T bonds, which we call isolobal bonds. These bonds are enabled through the support of main group atoms. The number of electrons shared in these bonds correspond to the "n" in the 18-n rule. https://t.co/qtT49WpGyV
In the case of ScAl3, we have 12 valence electrons, so using the 18-n rule... 18-n = 12 Then n=6! This is exactly what we see in ScAl3, which forms the AuCu3 type. Sc can form 6 Sc-Sc contacts, all supported by Al atoms. https://t.co/jvFocRsczg
For detailed reading and examples of the 18-n rule, I recommend this excellent article, aptly titled, "Generality of the 18-n rule". https://t.co/p0BS3orTge
What about the 18-n+m rule? m corresponds to the number of electrons that are NOT associated with the transition metal atoms. These atoms are based in main group-only states. e.g. for Ir3Sn7, 1 electron goes in the isolobal bond, and 1.33 electrons populate the Sn-Sn σ bond. https://t.co/6abvBRX41D
This electron-counting rule has been helpful for us to rationalize a number of structures! However, you can see in the below example that I can have different (n,m) configurations at the same electron count... https://t.co/eU7bCCYydm
Herein lies the problem of 18-n+m isomerism. If we can have multiple (n,m) configurations and still be electronically stable, how do we know which structure type is the best candidate? https://t.co/nRj4eKQe6S
This is where the FAST concept I talked about yesterday comes in! We break down the candidate systems into two analyses. (1) ⚛ Electronics: How does the 18-n+m rule apply? (2) 💥Atomic packing: What kind of packing tensions are present in the systems? https://t.co/8k1vDF2rp9
That's it for now! Later, I'll talk about the two analyses in detail, then bring them together to solve the conundrum of 18-n+m isomerism. 👋
Happy Wednesday! ☕ Today I'll be talking about the theoretical methods we use to explore our crystal systems! While I prepare those tweets, have another one of my desk companions 🦆 and a 20 oz. coffee mug for scale. My roommate got me this mug to celebrate this paper! https://t.co/0TtMmwXasa
As the holiday traveling season approaches, PACKING may be on your mind. How are you going to pack all those gifts and clothes into one carry-on bag? https://t.co/AAnVgljZ2G
Well, I don’t have an answer for that, but I do have a theoretical tool for understanding packing in solid state materials. Introducing the ✨DFT-Chemical Pressure analysis!✨ (TOC image from https://t.co/v5M8cTzizO) https://t.co/F9fsFWXFKW
What’s Chemical Pressure? Imagine a 2D lattice of atoms. These atoms are the same element and are placed at their equilibrium distances. If we replace one atom with a smaller one, its contacts must shorten but at the expense of other contacts! We have packing tensions! https://t.co/JWGN6NPnLU
We encapsulate this concept in calculating "chemical pressures" for our system. To do this, we: (1) Use DFT packages to calculate energies of our system at its normal volume, a slightly bigger one, and a slightly smaller one. (2) Calculate a pressure for every voxel (a 3D pixel) https://t.co/Ak7Qelv19z
(3) Project the 3D chemical pressure information onto spherical harmonics centered on atoms. This gives us a means to interpret contact-wise chemical pressures. * This is a simplified version of the whole DFT-CP process.
These spherical harmonics (called CP features) tell us which contacts are too long and which contacts are too short. Black = -CP. Energy DECREASES as the atoms come closer. The contact is too long! White = +CP, Energy INCREASES as the atoms come closer. The contact is too short! https://t.co/eNcTYOEyXU
These CP schemes are useful, as they can tell us what the local packing tensions are. In general, we can compare two CP schemes of structures of the same composition to identify which structure type reduces packing tensions, and how it does so!
One way I used DFT-CP was to look at a series of intergrowth structures in the REAl3 series! We combed through literature and found a trend that compounds with larger RE atoms tend to have more of the hexagonal Ni3Sn type than the cubic AuCu3 type. https://t.co/FqxQPBRBPr
This suggested to us that atomic size and packing effects played a large role in which structure type forms. But why? We could look at tables of covalent and metallic radii, but this wasn't enough for us. DFT-CP came to the rescue! 🦸♀️
We calculated the DFT-CP schemes of a selection of these compounds and found that the Ni3Sn type relieves packing tensions in the AuCu3 type for compounds with larger RE atoms (illustrated below with YAl3). https://t.co/Troza2MLMU
We can see some problems in the hypothetical AuCu3-type YAl3 packing scheme. The Y atoms have a white positive pressure all around it, meaning it's feeling rather constricted. Expansion of its coordination environment, however, is hindered by negative CPs along Al-Al contacts.
We can see how replacing the Y atom with something smaller, say a Sc atom, can be more favorable!
(Side note: Calculations are great! You can get information about hypothetical systems that you can't realize IRL with experiments! But of course, you need to be careful about drawing conclusions because it's a hypothetical system.)
When we compare this to the CP scheme of the Ni3Sn-type YAl3, we note some key differences: (1) Al-Al negative pressures are reduced within the newly formed columns (2) Positive pressures on Y are reduced in the ab plane, forming an hourglass shape. https://t.co/6lR37QcgUz
DFT-CP shows us exactly which packing tensions are relieved by the Ni3Sn structure type, and why it's a better arrangement for REAl3 compounds with larger RE atoms!
If you want to read more about this, plus some interesting electronic considerations, check out my paper in Inorganic Chemistry! https://t.co/CdSP9sMnTU
I also designed a very cool cover for that issue related to the work, which I think you should look at. 👀https://t.co/GHuBlrSYPX https://t.co/zVdIyGNEw0
Thanks for tuning into this thread over the DFT-Chemical Pressure method! Stay tuned later today for MORE applications of DFT-CP, including phonons! 😲
For reading on the Chemical Pressure concept and some advances in the methodology, check out these papers or our publications list: https://t.co/rfmpWr6HqR 1st CP paper: https://t.co/Hlfo0s2aEr 1st DFT-CP paper: https://t.co/sCgkhUKyV0 Latest updates: https://t.co/vw4FnnmcKt
Earlier today, I talked about the DFT-CP method. Now, let’s talk about a special CP feature, which we call the CP quadrupole! This unique feature is linked to cool phenomena, including phonons, incommensurate modulations, and guest atoms. Let’s dive right in! https://t.co/yRTt3LNQyt
CP quadrupoles (QPs) are features where the distribution of positive and negative pressures on an atom are perpendicular to each other. As a result, these QPs look very much like d-orbitals! https://t.co/noUZemz8Sw
QPs are linked to anisotropic motion of atoms. If an atom moves along the negative CPs, that motion or vibration will be relatively unhindered, resulting in soft atomic motions or low energy vibrations. https://t.co/ogt2ZUMV81
On the other hand, movement along positive CPs, where the contact is already too short, is very unfavorable, and vibrations in those directions will be higher in energy. These energies and atomic motions can be then linked to phonons... But what are phonons?
Phonons are vibrations for crystal structures. Instead of just one pairwise vibration, now we have concerted motions! (img src: https://t.co/cRFiczIjWw) https://t.co/YVObNRris4
So if QPs show us the directions of low and high energy vibrations, we should be able to see that in phonon band structures, which we do! The lowest frequency optical mode has displacements along those negative CPs, and the highest frequency modes has them along the positive CPs! https://t.co/97s7BxrlWk
This is exciting, because we can take this idea even further. One of my projects is the investigation of the polymorphs of IrIn3. The phase transition temperature is approx. 350C, which is pretty low for an intermetallic! Why is that? https://t.co/y3gITfcYBW
When we compare the CP schemes of both polymorphs, we see CP quadrupoles are present in the CoGa3 type but not the IrIn3 type. These QPs are enabled due to the large void spaces in the CoGa3 type structure, which the IrIn3 type doesn't have. https://t.co/zEQcOxzt65
And as expected, the atomic motions are correlated to low and high frequency phonon modes. In fact, the separation in frequency of these states is so large we see a phonon band gap! https://t.co/Qa2AoHhSJY
If we compare the phonon DOS of the CoGa3 type to the IrIn3 type, we see that the IrIn3 type doesn't have comparable low energy modes. This tracks, because any motions along negative CPs will be hindered by positive CPs. The IrIn3 type simply doesn't have as much QP character. https://t.co/L7mHmxA7DW
And this is a critical point: low energy vibrations are easier to access and thus contribute more to vibrational entropy than high energy vibrations, illustrated by the figure below. The CoGa3 type then must have greater vibrational entropy than the IrIn3 type... https://t.co/X9M65iOyNQ
We can then use our gen chem knowledge to do a simple calculation to get the phase transition temperature, using ΔG = ΔE -TΔSvib The phase transition should occur when the free energies are the same. Behold! Our calculated phase transition temperature is 410! Pretty close! 😲 https://t.co/FqHzIIMIP0
To demonstrate how important those low energy phonons (motions into the void spaces of the CoGa3 type), we artificially shift the frequencies in the CoGa3 type up +0.53 THz, and our "new" phase transition temp is now 912C, much, MUCH larger than before! https://t.co/Ki6wBa1Cqy
From this, I've learned two things! (1) CP quadrupoles are great for anticipating these high and low energy vibrational effects, which is awesome since they're cheaper than phonon calcs. (2) Those void spaces in the CoGa3 type enable entropic stabilization.
That's partly why the CoGa3 type is the higher temperature phase, and also why the phase transition temperature is so low for an intermetallic!
There's a lot more that CP quadrupoles can tell us. I won't spoil more for now, but I highly recommend reading this paper by Dr. Kendall Kamp, who did a lot of work in this area! https://t.co/nRX9vzP9ym
I'm also leaving a lot of cool details out in the IrIn3 polymorphism paper, so go read that too! I'm quite proud of this work. https://t.co/i7W0XEeLlF
That's all I got for now! See you tomorrow, where we'll be exploring ELECTRONICS and COMPUTATIONS!
RT @goldclusters: @RealSci_Nano My @InorgChem mug 🙂 https://t.co/sQWhuwhr6l
@goldclusters @InorgChem Love to see mugs from a fellow Inorganic Chemistry author!!
Good morning! Today I will be talking about the electronic structure analysis I do. A big part of it is running calculations and writing code! So I thought I'd give you all a sneak peak at what it's like to be a computational chemist. What's on YOUR desk? https://t.co/1rs4dJffUk
An essential part of being a grad student is running down to the seminar hall when they announce free food up for grabs. 🏃♂️💨 https://t.co/Cfyj4IsROv
Part of my work this week is writing a manuscript! Though writing is not my favorite aspect of research, it's an important process that helps me think deeply about my scientific findings and how it fits into what we currently know. Here's my flowchart with how I approach writing! https://t.co/KhGDPrdxo2
I start writing highly detailed work first (such as the experimental section), then slowly work towards more generalized or abstract sections. I like to leave the title for last! This allows me to brain dump, organize my thoughts, then form a larger story for my work.
So what does a computational chemist do to understand solid state structures? How does one even approach computations? Let's have a tour!
Say you want to know about the electronic structure of a solid state system. You know you can do ab-initio computations somehow! Where do you start? 🤔 You start with the crystal structure!
We typically use Crystallographic Information Files (CIFs) as a starting point for building crystal structures. I like to look in the Inorganic Crystal Structure Database (ICSD) for CIFs of my system, or if they're not available, CIFs of the same structure type as my system. https://t.co/hKcB8XPCJA
I typically open these CIFs in a visualization program like VESTA or Diamond to understand what's going on. For the compounds I study, drawing homoatomic bonds is very helpful! https://t.co/4KmdatVMLf
Next, I put the crystallographic information into the input files for computational chemistry packages. Our group uses VASP and ABINIT, two common DFT packages. Since these calculations can be intense, we use our department's computing cluster to run this software.
We have to run software from the command line. It's a bit of a hurdle when you initially learn it, but it is very powerful! 💪💻 (Plus it makes you feel like a hacker in the movies...) https://t.co/2UuSQZbphA
Not only do we need to put in crystallographic information, we have to tell the program what kind of settings we want to use! My input files start to look like some kind of hidden code. 😵 That's why I like to put some comments in my template files. https://t.co/BVOrCUhQJD
Let's fast-forward! The first calculations we do are for setting certain parameters, like the energy cutoff and k-point mesh. Though we don't get info from these calculations, we need to do this to find the right balance between precision and computational cost! https://t.co/AynZKG7ppD
This is important, because we can get *super* precise, but if your basic calculation takes months to run, it's not very practical.
Once those are set, we need to optimize our crystal's geometry! For our purposes, need to have our system at the energetic minimum to extract meaningful, accurate data.
We do this geometry optimization in two steps: (1) atoms are allowed to shift (2) atoms and unit cell shape are allowed to shift This two-step procedure helps the software find the equilibrium geometry efficiently. https://t.co/3GRK6MLf1x
Once we have our equilibrium geometry, we run static calculations, where the atoms are now locked in place and we can get the data we want!
For example, we can get info about the electronic density of states, which can tell us things such as whether our crystal is a conductor/insulator or what kind of orbital characteristics our bands have. https://t.co/AM4iFqqyEL
For my research, the region around the Fermi energy (EF) is of interest! Typically, compounds that follow the 18-n+m rule have a dip in their density of states at the EF in the form of a pseudo- or band gap. Sometimes, they don't, like in the IrIn3 type in the above image.
Why do some 18-n+m compounds not show that band or pseudogap at the Fermi energy? To investigate this, I use one of our group's tools called DFT-raMO! This is a tool that uses the occupied crystal orbitals (which we get from DFT calculations) to make molecular analogies.
DFT calculations on crystal structures use planewave basis sets to describe the information about the electrons of a system. Think sin and cosine functions! https://t.co/iiiGz55kxV
Instead of analyzing waves that are spread out, we want to understand the electronics in a localized context. This allows us to understand the bonding in our system by making analogies to molecular orbitals. https://t.co/qV3IBi4kmF
To do this analysis, we wrote software in MATLAB* that does some BIG matrix math to transform wavefunction information into approximate molecular orbitals! Each of these new functions contains 2 electrons, so we have a way of doing electron-counting for our system.
* It's in MATLAB, for now, but I'm currently rewriting it in the Julia programming language.
The plot here shows the output of some DFT-raMO analysis, with one dot representing one reconstructed molecular-like orbital. You can see that we're able to generate atomic- and molecular orbital-like isosurfaces! https://t.co/uyz1QsBRiF
But what's that on the y-axis? That's Psphere, which is a tool that helps us evaluate the localization of our reconstructed function. It's calculated as the ratio of electron density in a defined sphere over the electron density in the whole unit cell. https://t.co/WlVal4O82W
What's important to us is that Psphere is consistent, meaning our reconstructed molecular orbitals are well-localized. When it drops sharply, it's an indication of delocalization. Or in simple terms, electrons can't be fully occupying those orbitals!
This tool helped me with a lot of projects! Remember the REAl3 story? With DFT-raMO, I was able to show which orbitals were associated with electrons n=7 and m=1 in the 18-n+m rule! https://t.co/TbJI0elCDV
In the story of IrIn3 polymorphism, DFT-raMO helped showed that m electrons were localized in the void spaces of CoGa3! https://t.co/FUOX3470zS
There's still more we can plan to do with DFT-raMO, and part of my work is expanding its functionality by writing code! I've been working on the newest version of it for almost two years now, and I am pleased to say that it's more efficient and has quality-of-life improvements. https://t.co/XCxmx80BmZ
... and this is where we get into one aspect of computational chemistry. Coding and software! https://t.co/YZtafUzay7
Before I begin, a disclaimer: I haven't taken a single coding class since high school, so a lot is learned on-the-job or self taught! 😱
Not all computational chemists write code regularly, but sometimes they write scripts to automate their tasks or process data! These scripts are relatively simple. When you need a collection of scripts to perform complex tasks, you might consider writing a software package.
I find myself coding in short bursts rather than on a daily basis! This is because I have other tasks to do, like analyzing data or writing manuscripts!
But if you catch me on a coding day, my screen might look something like this! https://t.co/HEtXxnEOgl
I also use Github for version-control, which is something I learned a couple years ago. It has changed my life immensely, and if you are a coder but haven't used any form of version-control, what are you doing!!!
The coding process is usually: idea -> sketch it out -> attempt to code -> test -> debug -> debug -> debug -> debug -> debug ... -> commit change It's almost similar to writing a manuscript in that aspect. 😅
It's a challenging (and sometimes painful) process, but I also find it deeply rewarding, and I learn new things all the time! The biggest challenge for me is trying to keep the BIG PICTURE in mind while still minding all the small details.
I'm still working on my DFT-raMO.jl package, but I'm excited to get it published and shared with the scientific community so anyone can use it! 🤞 Coming soon 2024...
I'd love to answer any questions you may have about computational solid state chemistry, writing scientific code/scripts, or DFT-raMO if you have any!
In the meantime, I will close with relevant further reading! The DFT-raMO method: https://t.co/rZQMhYJRt9 Psphere update to DFT-raMO: https://t.co/CdSP9sMnTU
Of course, none of DFT-raMO would be possible without the contributions of the following: Original DFT-raMO: Prof. Danny Fredrickson, concept Dr. Vincent Yannello, lead and coding Dr. Yiming Guo, math and coding Dr. Erdong Lu, extra testing
For the current version of DFT-raMO, my colleague Brandon Flores (@inator_creator) was invaluable with his development of Electrum.jl (https://t.co/mjPCfzqLKT) which DFT-raMO relies on, and his knowledge of Julia and Git!
Thank you all for tuning in, and I'll see you tomorrow for the LAST day! 👋
Good morning, scientists! ☕ It's a cloudy day in Madison, and you can just see the Capitol from the chemistry building. Unfortunately, a crane is blocking the way. For my last day, I want to talk about my journey as a scientist, as well as fun stuff outside of research! https://t.co/CDmr8FMfOj
Like many other people, I didn't have a linear path to research! I meandered and explored other careers (journalism, anyone?) before deciding that I was set on entering graduate school for chemistry.
One key experience that led me to research was the opportunity to do summer research at the University of Texas at Austin with Prof. Lauren Webb and Dr. Annette Raigoza. This wouldn't have been possible without the funding of the Welch Foundation.
I had ZERO idea what research was like, and the experience was nothing like high school labs! I learned things like how to safely use a hydrogen torch, or how to use piranha solution to clean substrates. It was a whole new world to say the least.
I also learned about the less flashy side of science, which includes collecting data and writing reports. The poster I made still lives in my closet. I was even rewarded years later with seeing my name on a paper! https://t.co/8FGRatEbDF
This summer program was vital, because when I entered college, it prompted me to consider undergraduate research!
I joined Prof. Jakoah Brgoch's lab, and here, I had my introduction to solid state chemistry in the lab! I⚡ arc melted metals, 💎 grew crystals from flux synthesis, and performed powder X-ray diffraction! https://t.co/woTUBNIThh
However, some of my samples kept exploding in the furnaces! 💥😱 While we figured out what was going on, I started doing more computational work. I still have pictures of the apology brownies I baked at that time... https://t.co/ji7l18qEYi
I soon found out that I liked doing more computational work, and that lead me to pursuing further studies in computational solid state chemistry! And that's how I got to where I am.
I do miss doing experimental work, but I'm happy to watch my coworkers do grow crystals with new and exciting structures! Here, my colleague Jonathan Van Buskirk is showing what happens to the graphite powder insulating his sample immediately after microwave synthesis. https://t.co/TjQWpf0WOu
You might have seen some of my comics this week as part of explaining my science! I love drawing and making comics, so I try include them in my research as well! https://t.co/R6DKRF9Vyz
It's been a fun way to catch people's attention! I lure them in with pretty colors and then hit them with the science. 😈
Due to the complexity of my research, the comics I write aren't intended for the general public. Instead, I focus on crafting the comics for people with a basic understanding of chemistry, like undergrads! This helps keep the direction of the comic focused.
Our group does comics and interactive tools as part of our outreach! https://t.co/ss56YxDmg6 It is also a fun recruiting tool to get prospective graduate and undergraduate students interested in our work every time they pass by our student office. https://t.co/gcLpeY5yMe
We have a lot of fun designing graphics, especially around first-year grad student recruitment season! Here are some posters I designed for my group this year! You might be able to guess the theme... 🎸 https://t.co/y5icBBSSqf
Being obsessed with art has also given me the opportunity to collaborate with other scientists on graphics, including the thumbnail for my podcast episode this week! (1) https://t.co/zRK6pOPygD (2) https://t.co/Guc8sM9NUq (3) https://t.co/2HB8z1l3LG https://t.co/iJbnGSBIO1
I also learned how to use Blender when making my own cover! This took a solid week, 😅 but I'm grateful that my advisor was as excited about it as I was. (I highly recommend CG Atoms if you're interested in Blender https://t.co/zjX2DyXJKl) https://t.co/MQiseOmmx7
I also have fun making tutorials for my group members so they know how to use graphics software for their own figures! In this tutorial, I had them create birds with arms thinking various things... (You can access the tutorial here if you're interested! https://t.co/d2WQpWBhSe) https://t.co/NzTnPCwpkz
It's fun being an artist-chemist, and I'm not alone either. In fact, our department has a yearly zine featuring the creative side of our chemists! The latest issue was released yesterday, in fact! I do have a comic in there which you should check out. 😎 https://t.co/BYBUYmJ9A1
That's all I have to say for the *comics* side of my grad school experience. 👋 If you'd like to keep up with my work or even collaborate, you can follow me here on twitter @xamberlim or keep in touch on LinkedIn: https://t.co/alxQthie2h
RT @RealSci_Nano: That's all I have to say for the *comics* side of my grad school experience. 👋 If you'd like to keep up with my work or e…
Thank you Amber for a wonderful end of 2023! We loved the comics, chemistry, calculations, crystals and everything you shared with us😍 Everyone, give @xamberlim a FOLLOW! @the_ScienceTalk @Fredrickson_UW @UWMadisonChem https://t.co/6rWP0xT72r
2024
Doris Reiter
✨SUPER Quantum✨ Please welcome this week's curator - Doris Reiter who is a group leader at TU Dortmund University (Germany) Check out episode 215 of Under the Microscope 👇🎙️ @the_ScienceTalk @MySci_PK #SUPERquantum #QTorch #Quantour https://t.co/Ey4fs3SzpV
Hello from me! I am excited to be this week's curator 😊 As usual this week has a packed schedule. Today is our group meeting. Looking forward to discussing physics and more with Thomas, Jan and Quentin 😀.
Being a group leader is challenging: my aim is to support students in finding and nurturing their strengths, so they can shine in their best way. Giving positive feedback is an essential part of it!
We often have guests in our group. Sometimes, also experimental physicists like to learn how we do our simulations. We had great fun, when Yusuf @Psibilim from Innsbruck was visiting us😊. He solved a mystery in the data by programming a quantum dot system 👍
Another important part is to keep up spirits, especially when we cannot meet so often in person. Every meeting ends with a quiz about fun facts on pirates and princesses 🏴☠️💎, sea otters and turtles🦦🐢, .... I let you know later what today's quiz was about.
This evening is a lecture in our "Physics&Pizza" series. We invite young group leader to present their work and themselves in Berlin. The talk is followed by Pizza 🍕. If you cannot join in person, you can also follow online at 6pm (Berlin time) https://t.co/uprge9wOtv
The series is organised by the AGyouLeaP of the German Physical Society. No worries I will tell you more about AGyouLeaP this week. Looking forward to this 😁 https://t.co/MveEQO8N57
Today's topic was the city München! At the end of the week, half of the group will go there to attend the Quantum Dot conference: https://t.co/qPbKAbLJiq So it is important to know what Oktoberfesterizations are 😆😆😆
Good morning! Super proud about Jan, who re-submitted his paper yesterday evening 👏. He reveals a lot of quantum effects in optically driven quantum dots. See the oscillations below? Quantum dynamics in action! 😊 https://t.co/Q0rzwD7H0j
Suvived my exams 😆! Also as an examiner exams can be stressful 🥵. Find the right balance of questions - from easy to complicated-, keep in time, ask about more than one topic. I got some practice, so nowadays I am typically less excited than the students 😆
Conducting exams actually made me learn how to ask questions. As a student I was not the one who asked questions 🙄. But as examiner I learnt that even obvious questions might lead to interesting answers. Now I ask many questions, also after presentations. It's fun 😁
My experience from that also inspired me to have a new seminar form called: "Ask me anything: Quantum Dots". Each week one student asks me questions about quantum dots! One hour long⏱️! It is not as easy as it sounds!
I really enjoy that seminar. Why? Because I love talking about quantum dots 😊. I do know a lot about quantum dots, but I also do not have an answer to every question and I think that's okay.
@the_ScienceTalk There is so much to learn in that seminar! Learning to ask questions to keep the discussion flowing is such an important skill 👍. And we all learn a lot about quantum dots. For me, it does not feel like an exam, but more of a fun discussion round 😊
Working in Dortmund, you always have to be aware what is going on with the BVB - Borussia Dortmund with it's famous football team! My little friend in the office keeps reminding me about that. Today is a game in Dortmund. Wishing good luck for @BVB ! https://t.co/6wleVGwNHQ
TU Dortmund is a campus university. This week the weather is sadly grey in grey with grey. So taking pictures just looks like this today! Hoping for some sunshine soon @TU_Dortmund https://t.co/WqaglpdEwN
Today, I want to talk about being a group leader, in particular when starting a group and trying to get a standing in the academic world. Fours years ago we founded the AGyouLeaP - for young Leaders in Physics - within the German Physical Society. https://t.co/MveEQO8N57 https://t.co/Q86RrEeSLx
Founding AGyouLeaP lead us think about the questions what a young researcher is, as the definitions are plentiful and relative. This makes discussing problems related to this status group also difficult sometimes 🤔.
We wanted to bring young group leaders together, so they can exchange ideas. Starting to be a group leader bears a lot of challenges and many wish for some clues how to manage all the new tasks. Discussing this with your peers actually helps 😊!
We also want to give opportunities for young group leaders to present themselves. Like at the Physics and Pizza series. Hearing how they contribute to the physics world is super interesting! 😊
For me, AGyouLeaP was a big success and opened many doors. Now I am becoming an experienced group leader, so AGyouLeaP is now organised by new people. I hope it will continue successfully in the future. Wishing them all the best.👏
Just wanted to end the day with a SUPER picture (illustrated by Harald Ritsch). After our theoretical proposal (https://t.co/5d5h3Z385G) and the first experimental demonstration by @Psibilim and colleagues(https://t.co/PPnrH2MYKj), many more people tried SUPER in their Lab 👏 https://t.co/YcmdExkXQc
I was happy to see the data by Katharina measured in tha lab of Kai Müller in München https://t.co/XFY5QZ9z2F https://t.co/zPUB3SpbkP
The SUPER data from Stuttgart, measured in the group of Peter Michler and Simone Portalupi, are also cool. https://t.co/GAT8OIvAzg https://t.co/imkWdTzzIP
And I am excited about the SUPER data from a different platform: SnV centers in diamond, measured by our colleagues in Berlin in the group of Tim Schröder. https://t.co/4E8QvImlSs https://t.co/IayZDRL6gX
I am convinced that we are going to see many more SUPER data for different quantum emitters soon. Looking forward to that 😊😊😊
Home games in Dortmund really affect everybody. Traffic jams and Subways are full. You can see so many people wearing black and yellow! https://t.co/y3iBjqnJQK
Crocheting is a hobby I took up during Corona times. I finished that tonight. Do you recognise the special form? It's a hyperbolic pseudosphere😄. Its edges grow exponentially 😲. This will be present for a friend with all the beautiful colors 🤩 https://t.co/iFSdRoaHVB
Happy Pi day!!!
Have you already heard about QuanTour? QuanTour is our Outreach Project, which I organise together with @HeindelTobias . A quantum light emitter will travel across Europe and visit so many cool Labs. You can follow the journey here or on Instagram https://t.co/fJ7KJhgY5e https://t.co/WCgh7hC7AU
Every lab will measure what is called g2-function. If this function is (almost) zero at zero time, this proofs that a single photon is produced by it! Quantum physics at its best 😁 https://t.co/w0s0BF0zQf
I just clicked submit on a proposal for a project working together with so many cool colleagues like @DorianGangloff @MeteAtature and @Ar_Rastelli 🥳. We will do reserach on entanglement and quantum dots. So much cool quantum physics is about to happen 😎
Most of my office days I eat in the Mensa - the university canteen. Most students eat there, too. Today's menu was chicken nuggets and fries 😊. https://t.co/3AtxD6MFsx
Now my bike is waiting for me to go home. I am looking forward to this, today is a lovely day with sunshine and good mood ☀️☀️☀️ https://t.co/5vDkpLGJOK
This way a quick round: Happy to announce that Jan's paper got accepted for publication in Phys. Rev. Research! Congratulations 🥳🥳🥳. While the paper is prepared for production, you can read the preprint on arxiv: https://t.co/tLQG6s1B5c
Fridays I usually do home office. It's a great day to get some work done, think about some physics and write papers. Sometimes I start fridays with a typical German breakfast: Mettbrötchen 😋 https://t.co/pxJwKfGgQX
RT @HeindelTobias: ⏱️ Time is ticking for our DPG Outreach-Project QuanTour… 😉 ⚛️+🧳 🔜 🚂🇪🇺 = 🥳
RT @RealSci_Nano: ✨SUPER Quantum✨ Please welcome this week's curator - Doris Reiter who is a group leader at TU Dortmund University (Germa…
Quantumphysics is already explained in current issue of the german version of Donald Duck pocket books (in German: Lustiges Taschenbuch) 😎 So happy to see that Quantum Physics appears in modern pop culture! 😁👏🥳 https://t.co/nf6mnFrIHM
I'm impressed how good they capture the quantum computer system: This is just the cooling system, the quantum chip would easily fit in your suitcase. And the drawing for me it looks very much like the real thing 😀 https://t.co/wDcM2HknLe
Closing the work week, I want to tell some more about the fun physics we are doing. Here is an example of chirped pulses. Chirped pulses change their frequency during the pulse. You can also chirp with your voice, like birds do all the time 🐦🐦🐦 https://t.co/7f4UAeONrO https://t.co/Ejt8SISrPs
Using chirped pulses instead of normal pulses can have advantages. And opens more possibilities 😁. Phenomena like the adiabatic rapid passage can happen, but only it the pulse change is slow. Interested in that? Read our latest review on chirped pulses: https://t.co/5XnHrpvKWT https://t.co/x8NMAlyMGb
Quantum dots can also create entangled photon pairs😁. But you can to be careful🤨: The excitation process can impair the entanglement fidelity. Our theory was confirmed by our colleagues in Rome @FBassoBasset https://t.co/759IvqEaKZ https://t.co/MoeJnTPOu0
@FBassoBasset But no worries, the SUPER scheme can save you! If you put the quantum dot into a photonic cavity and excite via SUPER, perfectly entangled photons could be created at even elevated temperatures ⛱️🥵. Looking for someone to measure this! https://t.co/tmKBWiuWrK https://t.co/vSgceyZpRA
@FBassoBasset If you want to know more about my research, check out my webpage: https://t.co/O6y53ImUOU Got some more pictures and small summaries of our works there.
@FBassoBasset Congratulations 👏! It always nice to see your research being recognized. And it is a great experiment!
@Giulia_Pacc @FBassoBasset @TopolinoIT @TaroniAndrea I wonder in what other languages this quantum computer comic is found?
There is often the question: Do group leaders work all weekend long? I do and I don't: Today I need to clean my flat. That's work, right? 😀 What are you doing this weekend? https://t.co/U1azmZZD4D
No worries, I will also find time to relax today. Being in a relaxed and good mood really help me to do better science 😊😊😊.
Done with cleaning and chores. Now the rest of the day will be devoted to good old Pen&Paper roleplaying games 🐉 No posting during playing. See you tomorrow with more posts on conferences 😊
Good morning from the train to München on my way to the quantum dot conference. https://t.co/qPbKAbLJiq Excited to see many of my colleagues and to meet new people. And looking forward to learning about the latest news from the quantum dot community!
Tomorrow I have the honour to present our work on the SUPER scheme at the QD conference 😊. Also excited to see what others will present @Psibilim @FBassoBasset @senellartqd @VikasRemesh @DorianGangloff https://t.co/UfGJsl5xp1
@Psibilim Thanks for the traditional gifts @Psibilim ! Looking forward to discussions on the SUPER scheme this week. https://t.co/J3r0HBzU1x
Arrived at the QD conference @SNQSFinleyGroup ! Meeting so many colleagues is a SUPER start in the conference week #QD2024 https://t.co/Na2TDIeoWk
This is how München rocks @SNQSFinleyGroup https://t.co/hbZ6C2qtYw
I wanted to say bye to you all. The next days I will be at the Quantum Dot conference #QD2024 hosted by @SNQSFinleyGroup For more SUPER Quantum physics, follow QuanTour https://t.co/fJ7KJhgY5e or look out for more quantum physicists to on the Podcast. Was super fun! 👋👋👋
Narayanan T N
✨👿 Devilish Details of Nanoscale Interfaces👿✨ Please welcome @TnnLab for a week of materials and interface engineering🥳 🎧🎙️Listen to episode 216 of #UnderTheMicroscope where TNN talks about his research👇 https://t.co/26cvTNiTai @TIFRH_buzz @the_ScienceTalk @MySci_pk
1/n Hey all! Hello from the city of Hyderabad. 👋 I am Narayanan, an experimental material scientist. I am thrilled to be your curator for the week and bring to you exciting news about research from our group. @TnnLab @TIFRH_buzz Stay tuned for our lab updates...😀
2/n The last 10 years of our research (https://t.co/GebQNF01Vc) at TIFR Hyderabad, India mainly focused on the development and studies of materials for applications, in energy, including renewable energy harvesting, electrocatalysis, & energy storage, as well as, in electronics.
3/n Our materials engineering approaches reside in the modulation of different mesoscopic interfaces & probing their interfacial properties. For this we study light-matter interactions, electrode-electrolyte phenomena, interfacial electron/ion transport & quasiparticle dynamics.
4/n We also focus on the controllable development and optimization of atomically thin layers and their heterostructures using different physical and chemical routes.
5/n Light as a probing tool for materials’ topological properties is another active area of our research. We also have close associations with different industries and institutions around the globe in various aspects of our research.
Being an experimental scientist, it is my team-mates, including, PhD students, post-docs, & project fellows who play an integral role in running our lab smoothly. Let me take you on a virtual lab tour to introduce them & their work. https://t.co/X4F8F6SbcK @TnnLab https://t.co/HKQD0CxVrY
1/n As we are working on 4 broad areas, we thought of dedicating each day starting from today to the 4 different areas. Day 1: The Catalysis Day
2/n Catalysis is the heart of our research in general. We work on the development of novel catalysts, with scalability & industrial applicability. This is a recent work by @RayantanS in @ACS_AMI https://t.co/nJOTpgmfPo, with a low-loaded stable electrocatalyst for H2 evolution
@RayantanS @ACS_AMI 3/n We also try to fundamentally understand the catalytic process using various tools, like Raman scattering and Infrared spectroscopy, which are applied in-situ during the process. This is a recent work by @NanditaMohandas in @ACSCatalysis on this line. https://t.co/UUe3s6oXX4
4/n We are also closely working with National Mission Programs such as Hydrogen Valley Mission in different capacities.
5/n Bringing to you a short video explaining a part of our research on the development of viable electro- and photoelectro- catalysts for hydrogen generation. Here through an engaging video @RayantanS @NanditaMohandas and Amogh explain this in layman terms. https://t.co/rQtVe7dueq
1/n Day 2: Battery Day Our #batteryresearch during the last few years could find some niche areas of scope including charging Li-ion batteries from solar energy, safer Li metal batteries, high cyclability efficient Zn air batteries & plausible new anode materials.
2/n We developed a new way of directly using solar energy to charge electrochemical energy storage devices like batteries, where a 2-electrode photo rechargeable Li-ion battery is demonstrated. Check out this paper by @AmarKum25251564 and others- https://t.co/QgPUlBGb5a
@AmarKum25251564 3/n This work was covered by @EurekAlert. Click to read the article here- https://t.co/EVNiKqBf0Z
4/n We also work on the development of safer Li metal batteries as opposed to Li ion batteries through a separator modification approach. Preeti has been working on this front. Check out this from our group to know more-https://t.co/pJCEKBl4dQ
5/n @EurekAlert also covered this work from our group and reported a scalable and cost-effective method to assemble a safer and durable Li metal battery. Check out the link below to read- https://t.co/vwsIzbgDGZ
@EurekAlert 6/n Our research is also focused on the development of metal-air batteries especially using indigenous metals like Zn. In this video, I along with @subhra_srp and Pallavi explain the importance of such a battery system. @TnnLab https://t.co/5rhhSRwK5A
7/n In this work, Pallavi has shown an efficient enhancement of cyclability in Zn-air batteries using an electrolyte engineering approach. https://t.co/P8BZ1wfXUv Pallavi also got DST-AWSAR Award 2023 for her story where she explained this work. #scicomm https://t.co/Nxstkp10MQ
8/n In collaboration with other universities in India and abroad, we welcome visiting students to work in our lab, leading to fruitful research. In 2 recent works, we have proposed two new cathode materials for battery applications: https://t.co/DoHLqtBSqp https://t.co/4tSO1YZOm3
9/n Some of our ongoing funded programs in battery research (by Royal Academy of Engineering, UK) also include the "rural energizing of India using indigenous battery systems".
1/n Day 3: Light-Matter Interaction Day Light-matter interactions lead to many interesting phenomena around us, from aiding vision to photon -assisted 'quantum technologies'.
2/n We are interested in the studies of interactions of light with nanostructures, particularly aiming for the development of ultra-stable photodetectors to valleytronics-assisted data storage. Valleytronics is an emerging field for next-generation data storage.
3/n Valleytronics is about selectively populating the energy 'valley' of a material with electrons using light. Our works have given a clear insight into the development of such materials using engineering atomically thin materials. https://t.co/phXsXPPnRL https://t.co/xFQE25FnMc
4/n Similar papers on the same line are the following https://t.co/OTDHfDI2wl https://t.co/EaGt6hbsmf
5/n Excited to share with you all that one of my PhD students, Mr. Janmey Jay Panda gave his PhD Synopsis Seminar yesterday. He works on the photonic spin Hall effect for materials' properties, which is a wonderful new landscape we are currently exploring. Keep it up Janmey! 👏 https://t.co/XmsmmJ0HDN
6/n Atomic layers have high potential for applications in photodetectors. But their stability & sensitivity are issues for practical use. Our recent works addressed these issues, to be used even at harsh conditions. https://t.co/thDceWXhu2 https://t.co/vxfEjUTz6g https://t.co/wsT0ecJHFI
Hey all, yesterday I was completely held up with meetings after meetings. 😰 Our weekly group meeting and lab cleaning sessions also happen on Fridays. So couldn't update anything here. Don't worry we will resume today and I will bring you more news from our lab! 😃
1/n Day 4 (probably 5😅): Growth & Composite Development Growth and optimization of nanomaterials play a major role in exploring their possibilities in practical uses. Our group is eagerly exploring such activities right from the beginning for various applications. @TnnLab
2/n Our research led to the discovery of interesting scalable nanomaterials, corrosion protective coatings, water purification strategies, & thermally protecting mechanically reinforced helmets. Read our work which was highlighted as the cover page too: https://t.co/7dfy8adfJ8 https://t.co/4BCAL0ConA
3/n We could develop a rechargeable respiratory mask of N95 quality during the COVID-19 pandemic period . National media and major public platforms highlighted this work, The Hindu report is shown. https://t.co/CNyIaJ7l6Y @TnnLab https://t.co/BZUVUIxIGv
4/n We were also engaged in the development of a respiratory mask testing unit which can test up to the level of N95,as it was highly important to test the quality of the mask during the COVID pandemic. @TnnLab
Along with research, we are also actively involved in the science outreach activities of our institute @TIFRH_buzz. We give lab tours & experimental demonstartion to school and college students, instilling love for science right from the young age. 😃 https://t.co/Tp7La9A1WW
Another example of an outreach event I was part of. Interacting with young minds is always a pleasure. 🙂 https://t.co/sDPGO17Qmo
1/n I always believe science is a collective effort, & collaborations are always to bring out the best. We have many active collaborations at national, & international levels. More than just me collaborating, I always make sure my PhD students are an active part of it. @TnnLab
2/n As a part of our collaborative efforts, my PhD students have visited various labs around the globe and worked there for a few months. Three of our recent active collaborators are Prof. Doron Naveh, Prof. Angel Cuesta, and Prof. Andrey Turchanin.
3/n Dipak @dipak_maity97 visited Prof. Doron Naveh's lab at Bar-Ilan University Israel last year. The collaborative work was very successful and is soon to result in a nice publication.
@dipak_maity97 4/n Nandita @NanditaMohandas visited Prof. Angel Cuesta's lab at the University of Aberdeen, UK last year. The collaboration has helped us start a new area where we use IR spectroscopy as a probe to study the electrochemical interfaces.
@dipak_maity97 @NanditaMohandas 5/n Rayantan @RayantanS is soon to visit Prof. Andrey Turchanin's lab at Friedrich Schiller University Jena, where he will work on the electrochemical hydrogen generation from various new 2-D materials.
I am a researcher, as well as a mentor. A healthy & pleasant atmosphere in the lab is always my top-most priority. We have frequent lab dinners/lunches, as a part of success or farewell parties, & during festivals. Sharing here some recent such rememberable moments. @TnnLab https://t.co/jEuFQy9div
1/n The good-bye thread With that our @TnnLab one week of interaction with you is coming to an end. I hope we brought to you some exciting news from different interfaces of various materials. I would like to conclude with the announcement of #CARE2024 to be held at @TIFRH_buzz.
2/n #CARE2024 the International Conference on Advances in Renewable Energy is co-organised by me. The conference dates are yet to be announced. Follow @TnnLab to know more. We expect the participation of a bevy of eminent researchers from around the globe.
@TnnLab 3/n It was super fun to bring to you our research stories and updates for the past 1 week. Do follow us @TnnLab and check out our website https://t.co/GebQNF0zKK to know more about our research. Bye bye all. https://t.co/s99SkwTGUD
Thank you @TnnLab for a smashing week of surface & interfaces science! Give @TnnLab a follow!🥳 Do you want to take over this account for a week? Tell us here - https://t.co/6AUtCG9odL @the_ScienceTalk @TIFRH_buzz https://t.co/TwsMaOwf8g
Tobias Heindel
Please welcome this week's curator - @HeindelTobias for a wonderful week of experimental Quantum Science🥳 Listen to episode 217 of #UnderTheMicroscope to know what is coming your week this week - https://t.co/UHcsR0g0To @TUBerlin #QuanTour #QTorch #SUPERQuantum https://t.co/9YE5iiumIb
Hi All @RealSci_Nano! This is Tobi (@HeindelTobias) and I'm thrilled to curate the “RealScientists Nano” account this week 😀🎉 https://t.co/lY8opcRVcz
I’m a quantum physicist working on photonic quantum technologies and quantum networking. Leading the #QuantumFutur-group "Quantum Communication Systems" @TUBerlin, funded by @BMBF_Bund, I have the pleasure to work with a fantastic team! 🙏 That's our shiny group logo... https://t.co/SCiFGFcbVN
And our group website is ready for you to explore😊 👉https://t.co/rluu7sWBAr https://t.co/aVUoQ6zFYq
Germany's capital Berlin is a unique place in so many ways - also for doing science! 🔬+⚛️=🤩 Guess you know Berlin's three major universities #TubHubFub: Technische Universität Berlin @TUBerlin, Humboldt Universität zu Berlin @HumboldtUni, & Freie Universität Berlin @FU_Berlin. https://t.co/pOPChKq6dO
Since 2018, #TubHubFub together with Charité @ChariteBerlin colaborate within the Berlin University Alliance @BerlinUAlliance 👉https://t.co/7qpz7qhsd5
But Berlin's research ecosystem is even much richer! There are a large number of university external research institutions, e.g., Fraunhofer HHI @FraunhoferHHI, PTB, PDI @PaulDrude, ZIB @ZuseInstitute, WIAS @WeierstrassInst, HZB @HZBde, IKZ und FBH @LeibnizWGL, and many more... https://t.co/zA5MIWvoTs
Most recently, #BerlinQuantum (@qt__berlin) was born as the central hub for the thriving #quantumtechnologies ecosystem - which is especially important for my team's research at the intersections of #Quantum -Technologies, -Information, & -Networking! 👉https://t.co/fotjHPZoVG
I have the pleasure to work with an amazing team in my #QuCom group! The picture shows a snap-shot of our team (+ some family/friends 😉) during the 2023 edition of our yearly canoe trip in Spreewald... do you spot some familiar faces?🧐🙂 https://t.co/deNod6k9wu
...also here some impressions from our 2022 edition. So much fun in five canoes with quite some action involved...🛶+🛶+🛶+🛶+🛶= 😅😎 This time even guests from @QUANTUMunivie made it to our event - great! https://t.co/QNuuRXR4D3
⏱️ Obacht, time is ticking for… #QuanTour 🥳 The first official outreach project of the German Physical Society (DPG) on the occasion of the #QuantumYear2025! #QuanTour #QTorch #SUPERquantum @the_ScienceTalk a 🧵 https://t.co/ouID86t8ph
🎉 #QuanTour is getting real on April 14 @WorldQuantumDay and we are proud to be featured in this month's issue of the DPG magazine „PhysikJournal“ delivered to more than 50.000 DPG members! Wohooo… 🥳 https://t.co/jTuTHjNDlK
12 months. 12 labs. 1 source. 😎 In #QuanTour, a single quantum emitter will be send on its journey through Europe - an outreach project we are preparing since quite a while now. And the best ist, YOU will be part of it 🤗 More to be discovered here: https://t.co/LDLL9qLxEq
📣 Important: A few seats are still left for the #QuanTour Kickoff Event on upcoming Sunday = @WorldQuantumDay 2024! Be fast and secure your spot and register now (on-site in Berlin or online via Zoom): https://t.co/wI2yj1kNj6
But wait a moment… What is „the quantum emitter“? 🧐 And what is it supposed to do throughout Europe 🇪🇺? 🤔 Looks like we need (at least) another thread for this tomorrow… stay tuned for more science-related posts in the upcoming days 😉
⏰ Goooood mooorning routine at home starting around 6:15 AM with preparing snack boxes for the kids 👶 (kindergarten and elementary school). Today the quick version: puff-pastry ham-cheese roll from previous evening, mini tomatoes and as usual a surprise for the school boy… 😎 https://t.co/MwPznFcV5Q
Delivered oldest kid at school 💪 Now I‘m on my way to Berlin City (West)… Living at the outskirts of Berlin, or better say already Brandenburg, means the journey by S-Bahn takes some while 🚈⏳ But one is also close to nature and I enjoy the walk to S-Bahn a lot… 🌲🏃♂️🌳😊 https://t.co/c1E89yYG62
Today I give you first insights into our #QuCom lab! The time-laps video shows the installation of our cryo-optical double-table with two integrated attoDRY800 closed-cycle fridges. We use them to operate our quantum light sources at T~3K (-270°C)🥶 📽️by Daniel A. Vajner https://t.co/L46do5vxz4
We started literally from scratch for this lab in late 2022 - once our freight elevator has finally been fixed after a (too) loooong waiting time 😅 Back then we where so happy that the optical table and cage-system could be installed just 1 day (!) before X'mas...🎁🎄
The installation of the two attoDRY800 systems followed early 2023 and experiments where soon operational, thanks to the incredibly good job by my team, especially Daniel Vajner (@12305daniel) 💪 This is how the experiment looks today... 📸Konzept und Bild/Cathrin Bach https://t.co/rkvR2NRfb1
In episode 217 #UnderTheMicroscope @RealSci_Nano I mentioned that we love to generate quantum light from solid-state emitters. Something we do almost every day is to measure the quantum properties of single photons. This we do in a so-called HBT-type experiment sketched below... https://t.co/TcjRW2NwzK
Here 2 original publications... 📰Phil. Mag. 45, 663 (1954): https://t.co/5rh8Bh84Ag 📰@Nature 177, 4497 (1956): https://t.co/oq72RUkVj0 ...from the authors Robert Hanbury Brown (1916 - 2002) and Richard Q. Twiss (1920 - 2005), introducing the HBT interferometer for astronomy 🔭!
Using the HBT experiment one can access the photon statistics of a given light source in terms of the second-order auto-correlation function... https://t.co/imsCf9fiDe
@igordownunder @IciOuPas That puzzle piece is hidden in my theird comment/reply to the original post @igordownunder😉
🥁🥁🥁 This is how our quantum light sources look like! Micron-sized dartboards🎯fabricated on single pre-selected semiconductor quantum dots right at the center of the bullseye structure🤩 Magnificant fab by my team member Lucas Rickert👏 SEM-📸: Lucas Rickert https://t.co/a75RuB4CDM
Get ready for QuanTour 🚀 12 months. 12 labs. 1 source. #QuanTour #QTorch #SUPERquantum Thanks to DPG for showcasting our route! @MeteAtature @ArmandoRastelli @AntnSo @senellartqd Credits: S. Engberg/DER https://t.co/libwrOi8Hd
Such cute dartboards... 😅 Could be well suited for #QuanTour 🤔😉 #QuanTour #QTorch #SUPERquantum @MeteAtature @ArmandoRastelli @AntnSo @senellartqd
👩🔬👨🔬 Now, let's do the actuall experiment in our #QuCom lab using a HBT experimental setup (concept explained in earlier posts)! 📹This is a real-time video of what you get from the micron-sized dartboard 🎯 optically excited using a 80 MHz pulsed laser... 📹Credits: D.A. Vajner https://t.co/lVHN2cSSRY
💡Some explanation: Y-Axis: g(2)(t) X-Axis: t Hope you can see the missing peak at t=0 … 😉 This is #antibunching, i.e., the micro-dartboard 🎯 really emits single photons one by one… 🚀🥳
@MeteAtature @ArmandoRastelli @AntnSo @senellartqd You wonder about the desgin detailes? We published the blueprints for these type of devices some time ago... 📰Rickert et al., 2019: https://t.co/IVD25RONcQ 📰Rickert et al., 2023: https://t.co/thFTX41RFZ Worth stressing the important contributions by @CNOatZIB @ZuseInstitute https://t.co/ePYpJL25qc
You wonder what we are doing with the quantum light sources once working properly? We use them for applications in #QuantumCommunication and #Networking 🛜 This 📄 demonstrated a #QKD testbed using a benchtop single-photon source published @AppliedPhysRev @AIP_Publishing… https://t.co/VkCcq2UVGy
… https://t.co/upIINoDO1B
Back then, this was a highly collaborative work of my #QuantumFutur group #QuSecure @TUBerlin funded by @BMBF_Bund (@photonik2020 @QuantenTech) and @Einstein_Berlin via @ERU_Quantum with contributions by @TUBerlin @PWr_Wroclaw @UMCSLublin @Fibrain and @CNOatZIB @ZuseInstitute!
Happy that it was selected as an Editor's Pick an came with a #Scilight article @AIP_Publishing written by Ashley Piccone 🤗 https://t.co/XMuWUD7gV4
@EngelJona @AppliedPhysRev @AIP_Publishing Thanks! 😊 Yes, the qubit-state analyzer part in the image can be nicely integrated using PIC devices - if you have one we‘d be happy to test them 😅 For the detectors themselves (not shown here) it’s not so easy for telecom wavelengths. We used SNSPDs, also requiring cryotech.
Yes, he did it! 🤗 Today Dr. Timm Gao successfully defended his excellent PhD thesis as first PhD from my Berlin #QuCom group 🥳 I’m proud of his achievements and his performance today! He will continue to shape the 2nd quantum revolution - since last year in a company. https://t.co/megLMJyb8Z
1st authorship paper #1/3: 📄 T. Kupko et al., npj Quantum Information 6, 29 (2020) Tools for the performance optimization of single-photon quantum key distribution https://t.co/thvZpl9cqg @Nature_NPJ
1st authorship paper #2/3: This one we discussed earlier alteady 😉 📄 T. Gao et al., Applied Physics Review 9, 011412 (2022) A quantum key distribution testbed using a plug&play telecom-wavelength single-photon source https://t.co/upIINoDO1B @AppliedPhysRev @AIP_Publishing
1st authorship paper #3/3: 📄 T. Gao et al., npj 2D Materials & Applications 7, 4 (2023) Atomically-thin single-photon sources for quantum communication https://t.co/bD7ZBw1hUo @Nature_NPJ #npj2dmaterials https://t.co/jVxn19YXvm
Beautiful weather today at 20 degree Celsius 🌡️ ☀️ Just right for some garden „work“. Try to reorganize the firewood beneath the kid‘s playhouse. You‘d never guess where I got the wood for the red crane 🏗️ … thanks @SingleQuantum for the high-quality in your delivery crates 😅👍 https://t.co/kty74nDFIa
🤗 Tiny sneak peak for tomorrow @WorldQuantumDay 2024… just for you @RealSci_Nano @the_ScienceTalk @TUBerlin @qt__berlin 😉 Join QuanTour - A QuantumEmitter‘s Journey through Europe… 🚀 12 months. 12 labs. 1 source. #QuanTour #QTorch #SUPERquantum https://t.co/6lDnnFdxE1
Wohooo… 🥳 Today’s - ähhh sorry - yesterday’s Kick-Off Event for the QuanTour outreach project has been a blast…💥 We had an exciting evening at PTB Berlin and „The Quantum Suitcase“ collected it’s first stickers. Tomorrow morning it will embark on its journey to Austria… 😊 https://t.co/mzd6mhfKmf
12 months. 12 labs. 1 source. #QuanTour #QTorch #SUPERquantum
@Ar_Rastelli @AntnSo @MeteAtature @MySci_PK @DorisEReiter @HeindelTobias @TUBerlin
Time to say Good bye...🤗 It was an intens week, with my 1st PhD student defending his thesis and the #QuanTour KickOff. I enjoyed curating @RealSci_Nano and hope you liked my content. Please follow me @HeindelTobias and check out our recent #Review📰: https://t.co/ubQWwAYjjw 👋
Thank you Tobi for an amazing week of quantum science! Do give @HeindelTobias a follow🥳 https://t.co/crnnDrelbr
Armando Rastelli
🍪 Chocolate Chips & Relaxed Quantum Dots🍪 Please welcome this week's curator - @Ar_Rastelli of @jkulinz 🥳 Check out episode 218 of #UndertheMicroscope where Armando candidly speaks about his research - https://t.co/8zjKQAci8S @the_ScienceTalk #QuanTour #SUPERquantum #QTorch
Hello, we are @ar_rastelli, Maximilian and @elaederjahn and from today we will take you with us for a week through our exciting everyday life at @JKULinz! You can expect insights into laboratories, some interesting information about quantum physics and much more! https://t.co/oIJs1lDLxN
I, Max, am a PhD student at the Semiconductor Physics Division in the group of @Ar_Rastelli. My research focus is on quantum dot spectroscopy. (right)
I, Michaela, am responsible for science communication and transfer at the Cluster of Excellence Quantum Science Austria and am busy writing my doctoral thesis in this field! (left)
Our university is located in Linz. Our city is kinda different than other well known Austrian cities. But Linz has embraced this charming otherness. Here you encounter contrasts that are refreshing. Industrial flair mixes with a modern culture. Linz has something for everyone! https://t.co/oeFpCy7ssL
On the way from the main station to the @jkulinz , the "Bim" gets you to many exciting places: For example, to the @ArsElectronica, the museum of the future, which is a must for all art and tech lovers. https://t.co/9h3Hx4xkTQ
That's a lot of points, isn't it? A total of 24,000. That's how many students are enrolled at the @jkulinz. From Law over Medicine to Artificial Intelligence – JKU offers over 75 study programs. Which one would you choose? #QuanTour, #SUPERquantum, #QTorch, #NotchFilter https://t.co/7vXwqngAuw
How have you revolutionized the world today? Personally, I've made a cup of coffee so far. At the beginning of the 17th century, Johannes Kepler formulated three laws of planetary motion. Since then, we know that the planets move in elliptical orbits, for example. (1/2) #QuanTour https://t.co/uoYgPeZasc
The @jkulinz is located on a large campus where you can easily exceed your daily walking goal. Numerous buildings are surrounded by green spaces, large trees and a pond that mainly belongs to the ducks and fish. Isn't it beautiful? #QuanTour, #SUPERquantum, #QTorch, #NotchFilter https://t.co/pgYty09N3u
In light of his achievements, it's only fair that we named our university after this innovator who lived for 15 years in our city, right? (2/2) #SUPERquantum #QTorch #NotchFilter
At the campus there's always something going on. Last week we met someone who was watching solar flares and we were invited to take a peek. It was awesome! An insider tip: you have a great view over Linz from the Somnium building. #QuanTour, #SUPERquantum, #QTorch, #NotchFilter https://t.co/JgQmUzOYe9
And my name is Armando and I am head of the Institute of Semiconductor and Solid State Physics and professor at @jkulinz. In my research, I mainly deal with GaAs quantum dots. #QuanTour, #SUPERquantum, #QTorch, #NotchFilter
At our Institute for Semiconductor and Solid State Physics at @jkulinz we investigate electronic, optical and magnetic properties of semiconductor structures and develop new materials and devices. And I guess we are pretty good at it! #Quantour #QTorch #SUPERquantum #NotchFilter https://t.co/byOSah61xY
In our great team, we do it all. From the growth of various structures to further processing in the clean room to electronic and optical characterization. We therefore have access to excellent infrastructure at #jkulinz. Stay tuned for an lab tour! #Quantour #QTorch #SUPERquantum https://t.co/9rN6HB0738
As @jkulinz we are also very happy to be part of Quantum Science Austria! QuantA unites over 60 research groups. The vision of all involved is to gain groundbreaking insights that could change the view of what we know about the quantum world! #quanTour #SUPERquantum #QTorch https://t.co/HByn8wn3J9
You know Schrödingers cat? Imagine your morning coffee like this! Before you take a sip and sense its temp, it's both hot & cold, just like the cat, alive and dead in its box. Coffee, where quantum physics meets your morning routine! #Quantour #SUPERquantum #QTorch #NotchFilter https://t.co/E3rfhclVkG
@elaederjahn visits Max in the lab and takes a few pictures while he explains to her how the laser he is repairing works. Outreach is an important thing to us, because we also want to inspire non-physicists about our great professions! #QuanTour #SUPERquantum #QTorch #NotchFilter https://t.co/DXuhLDonc2
RT @RealSci_Nano: @elaederjahn visits Max in the lab and takes a few pictures while he explains to her how the laser he is repairing works.…
Working in a team often leads to a quicker solution to a problem. Here we had to install a device that we had never used before. It allows us to see the temporal shape of laser pulses. And guess what? After half an hour, we had figured it out. #Quantour #Qtorch #SUPERquantum https://t.co/matMFKva1B
Ever seen a pulsed laser? That's a laser blaster like the one in Star Wars. We did adjustments, so we had to open the cover. It shoots 80 Million times a second and you can literally burn things with it. What a nice toy to play with. #Quantour #Qtorch #SUPERquantum #NotchFilter https://t.co/NnihD78z05
This is the metal container where all the magic happens! Our breeding box for the structures we fabricate – a Molecular Beam Epitaxy machine. You can grow crystals with ultra high purity and precise control about the thickness of material layers. #Quantour #SUPERquantum #QTorch https://t.co/ARAdkqgIg2
What actually is the Quantour source? It's a semiconductor containing a tiny cluster of another semiconductor, which makes up a quantum dot. In this case it's InAs, surrounded by GaAs. Here, an image with quantum dots glowing using blue light💡💡 #Quantour #SUPERquantum #QTorch https://t.co/7FOdtSnTwU
For electrons in the quantum dot, they see their environment similar as you when you fall into a hole so deep, you can’t get out again. https://t.co/RVCU5bH6qu
In quantum mechanics, we describe particles with wavefunctions. So also our electron inside the quantum dot is a wave. And it can only have specific wavelengths, given by the size of the quantum dot, which impacts the electron's energy. https://t.co/OBZEpQ7fyz
This leads to the emission of light with a very sharp color. In this case, it’s near infrared light. X-axis : Photon wavelength (color) Y-axis: Amount of light per time https://t.co/xfW1MJc0dX
Ready for the Quantour sample? Here you can see a microscope zoom on the structures we currently investigate. The magnification ranges from 20X to impressive 6000X. #Quantour #SUPERquantum #QTorch https://t.co/jgCPWRUYXm
Finally, the Quantour experiment at @jkulinz . @HeindelTobias already explained the concept of a HBT experiment. Not perfect but still quantum – single photons. Stay tuned for an explanation of the detectors tomorrow. #Quantour #SUPERquantum #QTorch https://t.co/Hfu6DAiLzX
Lucas from @TUBerlin and me being fascinated by our new detectors. Superconducting nanowire single photon detectors from @SingleQuantum . User friendly and really fast 🚀. In there it has 1.9 K 🥶❄️ Explanation will follow⬇️ © @DorisEReiter #Quantour #SUPERquantum #QTorch https://t.co/6NyBJ9JnJ2
The detectors are based on superconductivity. In a superconducter electrons form Cooper pairs below a critical Temperature. The Cooper pairs are able to flow through the material without giving off energy. Therefore the resistance is zero. https://t.co/mAqVVQGKMm
There is a critical current above which the detector loses its superconducting state. If the detector is operated slightly below this current, a photon hitting the detector will break Cooper pairs and create a resistance region, resulting in a measurable voltage spike.
Bye bye Linz 🚄🥲 #Qtorch continues its journey and started the trip to Rome 🇮🇹 Lots of pizza, pasta and ice cream coming🍕🍝🍦 It was a pleasure to be part of this amazing project😊 #Quantour #SUPERquantum https://t.co/Zl0vmaISYg
Rinaldo Trotta
😎Stressed for Quantum😎 Please welcome this week's curator: Rinlado Trotta @QuantumMinions of @SapienzaRoma Want to know why Rinaldo insists on stressing the Quantum dots?Answer in video: https://t.co/M8WyOPg9mp @the_ScienceTalk @mysci_pk #UnderTheMicrosope #QuanTour #QTorch
Rome! Caput Mundi, soaked with history and art from all the centuries, hauling sparks of beauty behind every corner; wonderful when bathing in the sunlight, romantic and inspiring when enfolded by the night. A bit too much, you may think.
https://t.co/rXbZjHVRXz
“Oh Rome! my country! city of the soul! The orphans of the heart must turn to thee, […] What are our woes and sufferance? Come and see The cypress, hear the owl, and plod your way O'er steps of broken thrones and temples, Ye!” https://t.co/GkhB6Yt52w
Hello there, we are the Nanophotonics group! During this week, we will keep you updated about the journey of the quantum source. So, without further ado, to the next stop!
Rome! Caput Mundi, soaked with history and art from all the centuries, hauling sparks of beauty behind every corner; wonderful when bathing in the sunlight, romantic and inspiring when enfolded by the night. A bit too much, you may think. https://t.co/dCX6LZ0xcW
Of course, we are Romans, we love our hometown. So, as we stroll around the city, let’s hear what George Byron (clearly not a Roman) has to say in this regard:
“Oh Rome! my country! city of the soul! The orphans of the heart must turn to thee, […] What are our woes and sufferance? Come and see The cypress, hear the owl, and plod your way O'er steps of broken thrones and temples, Ye!” https://t.co/46cJxltWkW
Such was the soothing and melancholic impression that Rome bestowed on Lord Byron; indeed, how can you feel differently walking along Via dei Fori Imperiali, connecting the Colosseum to Piazza Venezia? https://t.co/Wdl8Bg7JQ6
We are surrounded by the ruins of the social center of the city under the Roman Empire: the Imperial Forum, composed of five monumental squares, built under five different emperors over one and a half centuries. https://t.co/jnqeRE4zOK
And this is such a small part of what Rome can offer. In Rome, you will find: a total of 5 UNESCO sites (a world record for one city!), more fountains than any other city on the planet, and more than 900 churches (can you recognize the one in the pic?) https://t.co/CUJMbaNUUY
As Rome has always been a must-stop place in any European tour, our quantum source could not miss the opportunity of spending a couple of spring weeks here, with the Nanophotonics (@QuantumMinions) group @SapienzaRoma University! #QuanTour #QTorch #SUPERquantum https://t.co/cBjjsBg6Ol
@SapienzaRoma is one of the oldest and most important Universities in Italy. With more than 100000 enrolled, it is the institution with the highest number of students in Europe! People come from all over the country to study here.
Founded in 1303, @SapienzaRoma has the “Città Universitaria” as its nerve center: the campus, built in the 1930s, features some architectural must-see. Pay a visit to the Math Department, designed by the world-renowned architect Gio Ponti! #QuanTour #SUPERquantum #QTorch https://t.co/rhhpo3Ya0e
The Physics Department in @SapienzaRoma is one of the most prominent in Italy, both for the cutting-edge research we currently develop here and its bright history. Let’s take a look at the department as it is today!
Two main buildings, hosted in the @SapienzaRoma campus, are part of the Department of Physics: the “old physics building”, dedicated to Guglielmo Marconi, and the “new physics building”, named after Enrico Fermi, who taught here from 1926 to 1938. https://t.co/OsrzJANG4H
And look here! A letter from Lawrence to E. Fermi himself. This is the kind of evidence that is carefully kept in the halls and the stunning museum of the department, together with experimental equipment from the last two centuries! https://t.co/rPNg8PCjiP
But, as we said, it’s not all in the past! Giorgio Parisi, 2021 Nobel laureate, used to work and teach here until a couple of years ago! https://t.co/7iQqgtOqPM
Ours is a large department, where both theoretical and experimental physics are cultivated in their wide variety: astrophysics, gravitation, superconductivity, quantum field theory, statistical physics, spectroscopy, photonics, and quantum information.
And here we are too, the @QuantumMinions group. In the next few days, you will learn something more about us: what we do and what we like, how we are so very different, and how, somehow, we manage to accomplish great things together! #QuanTour #QTorch #SUPERquantum https://t.co/ETvjkp2UiB
If you are following QuanTour from its start, you have already met the quantum dot: a nanostructure made of tens of thousands of atoms. We are interested in how they emit entangled photons. https://t.co/6Q9KqFssxq
Entangled particles behave as if they were a pair of dice that, after having been entangled, roll and always return the same but random outcome. https://t.co/rSJFzEcLPF
In our game, instead of a number the information is encoded in the polarization of light https://t.co/VXthaqMuW5
In fact, we have plenty of ways to control, manipulate polarization https://t.co/oGEPUfzEwq
Decades passed before this phenomenon was experimentally demonstrated for the first time in the Eighties, which won Alain Aspect the Nobel Prize last year. https://t.co/umflwjHOtg
Today, the whole research community is making an effort to generate entangled photon pairs fast and on demand, dealing with the many effect that can introduce errors in the process. #QuanTour #QTorch #SUPERquantum https://t.co/BlZjoHyzWt
One technical approach we develop and use is pulling and stretching our samples. Yes, one can do that even with apparently brittle and rigid materials such as the ones we use! https://t.co/VUqXu2GZAl
A semiconductor material containing the quantum dots is thinned down to 30 micrometers, a third than the thickness of a typical human air, and glued on a piezoelectric material that can apply stress upon the application of voltage. https://t.co/cOxjVYTE54
The geometry shown in the picture, developed together with @jkulinz and FH Voralberg and dubbed “the six legs’, allows us to stretch the sample in any given direction in its plane https://t.co/JkdaukEhW0
We use this to compensate for very small asymmetries in the shape of the quantum dot which are detrimental to the generation of entangled photons (here the sketch of the most recent device developed with the additional contribution of @Uni_WUE) #QuanTour #QTorch #SUPERquantum https://t.co/oEQrQxJ1v0
As entangled photons become a more exploitable resource, we can use them for practical purposes, such as sharing secret keys between two parties. https://t.co/tyNJvyeNtM
We have done this with the group @qlab_sapienza, led by Prof. Fabio Sciarrino, linking the two Physics buildings in the main campus of Sapienza University https://t.co/dtxlopJMcp
Despite these signals being very weak compared to sunlight (a photon flux 20 orders of magnitude weaker!), we are able to transmit them also during the day using smart geometries and spectral filters. https://t.co/Ek3EM87BsF
The process starts with the exfoliator tools: crystals, gels, and, of course, tape! We peel the crystals from the bulk to get the monolayer, which we transfer on the piezoelectric substrate. https://t.co/kUxyB5YXQm
With the sample at hand, we cool it down and quantum light appears! We explore how dynamic strain fields affect the exciton energy, intensity, and magnetic response! https://t.co/3lA8ydSaNq
Quantum light comes from the 0D-world, true, but…we can take it also from Flatland! Deformations and defects induce quantum emitters in 2D semiconductors, crystals one-layer thick. We place them on piezoelectric actuators, which allow us to tune their energy and brightness. https://t.co/FxqMrFiEvJ
The process starts with the exfoliator tools: crystals, gels, and, of course, tape! We peel the crystals off the bulk to get the monolayer, which we transfer to the piezoelectric substrate. https://t.co/7nXC64iSCe
We can process them in an anaerobic chamber, which keeps the sample clean from oxygen contamination. https://t.co/RIsBt56DV0
With the sample at hand, we cool it down in our cryostat and quantum light appears. We explore how dynamic strain fields affect the exciton energy, intensity, and magnetic response! https://t.co/MpbbnHKTxa
RT @RealSci_Nano: 😎Stressed for Quantum😎 Please welcome this week's curator: Rinlado Trotta @QuantumMinions of @SapienzaRoma Want to kno…
Now that you know our work, it’s time to know our people, the actual foundation of any research group. Let’s give a closer look to a day in the life of the @QuantumMinions members, starting from our PI, Rinaldo!
It’s early in the morning, a little boost is necessary: what’s better to start off a tough day at work than a black espresso? https://t.co/YohIijPuYO
Office time: checking the inbox, dealing with bureaucracy, pondering over new results and new ideas; but always with a smile! https://t.co/iYYCvkkNdH
Rinaldo then meets a student from the Erasmus Mundus QUARMEN programme: an innovative EU-funded master course that allows highly motivated scholars to be introduced to the world of quantum technology https://t.co/APhbg3Hw0b https://t.co/7LScZYl5xV
Students from all over the world spend each semester in an institution among @ParisSaclay, @UofT @UPorto and @SapienzaRoma. @SapienzaRoma is the first destination, where QUARMEN students attend Rinaldo’s Quantum Optics course. #QuanTour #QTorch #SUPERquantum
Teaching is a very important part of Rinaldo’s activity: here he is, answering questions at the end of an Optics lesson. https://t.co/F1s5SOPBON
But today’s a very important day, and his presence is required: two @QuantumMinions master students are graduating! Kudos to Leone and Pierpaolo! https://t.co/miIz0MyhPq
Such a stressful day: time for another coffee. Or maybe two. That’s Italy, what can you do about it? #QuanTour #QTorch #SUPERquantum https://t.co/L8M2i4ionZ
A special guest arrives and at @QuantumMinions we try to make him at home, welcome Maximilian! https://t.co/0g0Zbnix4u
Notwithstanding the many duties that keep him busy every day, Rinaldo always finds the time to step in the lab for a little discussion https://t.co/pZrRC9xxHy
But enough for now about Rinaldo, it’s time to meet the other members of the @QuantumMinions family! #QuanTour #QTorch #SUPERquantum
How's a day in the life of @QuantumMinions? First of all, we have to get to the Lab. In Rome, that is not straightforward: whether you come by car, bus or train, you know when you leave, but you never know when you'll arrive. #QuanTour #SUPERquantum #QTorch https://t.co/4u90Yi2dfh
Look, Michele just arrived on his bike! Michele is a Researcher and he has expertise on a wide variety of topica: he can deal with optics and sample growth as well as with hydraulics and electronics (but don't let him get too close to your PC, he likes to open them). https://t.co/C9do6CRqJG
Francesco is already in his office writing, thinking...he Is a Researcher, too, and he always hands out great feedback to any question: he usually points out how the things you are doing are wrong in this and that regard, but I guess someone has to do that, right? https://t.co/YeSobsKIdV
Of course, PostDocs need to start their morning with coffee, too; and alongside the coffee machine, we find Alessandro. He is in a complicated relationship with quantum dots, but he is fond of math and writing. Go to him if you need a break: he's always up for that! https://t.co/bici034SOD
Lab Time! Let's visit our heroic PhDs. Giuseppe is all about 2D materials, a big fan of light polarization and always ready to lend a hand. But sometimes it is hard to keep up and he has to ask for help. Cheer up, Peppe, you're the best! https://t.co/upW3c6Gp98
We cross the door and, in the other lab, we find Mattia, absorbed in his work. There is no dot he can not excite and he is afraid of nothing. No kidding, he is scary. https://t.co/AaAFp4tL6S
Time for another well-deserved break. Let's go for a stroll in the beautiful Physics Department "zen garden" and say hi to the turtles! https://t.co/gvroiiBsrk
Walking back upstairs, we meet Carola in her office, busy as always: she is a natural problem solver and there is no bureaucratic conundrum that she can't handle! https://t.co/ZZxhMgFXXy
The clock hits 1 p.m. and the @QuantumMinions head for lunch. Well, to be honest, it is hard to get these people out of the lab, and the process of actually going for lunch can get intricate. But, once outside, it's just smiles in the sunlight! https://t.co/PYW3LoVI3T
Our Master students really give it their all: meet Fabrizio, Silvia and Fabrizio, working hard on their theses! https://t.co/9PTJlREdEb
Even when the night comes, our activities do not stop! We opened our lab to the public in the context of the European Museums Night, letting the visitors in to discover about our research and, of course, the QuanTour! https://t.co/WNA187XpZh
Here is Giorgio, another @QuantumMinions Master student, introducing people to the incredible things we do with light and quantum mechanics. https://t.co/ZByef9vKu6
It's late now and the @QuantumMinions go home. It's been a busy day and tomorrow is going to be another tough one: we will finally show you the QTorch! #QTorch #QuanTour #SUPERquantum
It’s finally time to see what our QTorch can do! The @QuantumMinions are ready to mount the sample https://t.co/VhcHn64YU6
Mattia handles it like a pro! A little bit of silver glue and then, with care, the sample is in the stick. https://t.co/ok1lWRvAn8
Slow and steady, Fabrizio! Don’t drop it! Once in the cryostat, the sample will reach 4 K, close to the temperature of deep space! https://t.co/WcXG0oDrb8
The sample is cold, let’s get this dot excited! First of all we have to explore the sample, imaging and looking for the bullseye cavities built around the dots. #QuanTour #QTorch #SUPERQUANTUM https://t.co/pMHoQSzVlP
Lights on! The source is emitting. Giuseppe and Fabrizio couple the signal into single-mode fibers in order to get it to our single-photon detectors. https://t.co/yjvwm9slWj
Now we want to see if this source hands out single photons. So, we perform a g(2) correlation measurement (as they did in Linz, do you remember?). Look! Almost no coincidences! We are truly observing single photons! https://t.co/Re9qHzNbk0
We keep characterizing the emission, measuring the lifetime of the excitation and then, we have another idea… #QuanTour #QTorch #SUPERquantum https://t.co/UEACENv9pZ
Since we have our source up and running, let’s play a little bit. In our AttoDry1000 cryostat by attocube systems, we have the possibility of applying a magnetic field up to 6 Teslas!
What happens when we increase the magnetic field directed along the z-axis? We induce a Zeeman splitting in the energy levels. We can see them split while we increase the magnetic field! https://t.co/pfJLWKu6AD
The external magnetic field couples to the excitonic complexes' total angular momentum and removes the degeneracy in the projection along the z-axis. #QuanTour #QTorch #SUPERquantum https://t.co/m4m5jUkYw8
Thank you Rinaldo and team for a wonderful week of science! Everyone, give @QuantumMinions a follow🤩 #SUPERquantum #Quantour #QTorch @the_sciencetalk Make sure to follow Under the Microscope on Spotify or wherever you listen to podcasts - https://t.co/OgFZALRzwK https://t.co/BR67V3cIO5
Jens Osterhoff
🚀Next Generation Particle Accelerators with Lasers & Plasma🚀 Please welcome this week's curator: Jens Osterhoff of @LBNLatap Checkout episode 220 of #UnderTheMicroscope podcast to learn more!👇 @the_ScienceTalk @MySci_PK https://t.co/3Y1R7dzzHb
From 300 Meters to 3 Centimeters! 🌟 Jens Osterhoff shares how they've managed to shrink a 300-meter-long accelerator down to just 3 centimeters using advanced technologies. @LBNLatap @RealSci_Nano @MYSci_PK #UnderTheMicroscope https://t.co/O36I5LrBrB
Really excited together with my @LBNLatap colleagues Carl Schroeder and Eric Esary at the start of the most important workshop on advanced accelerator concepts, the #AAC24 in Naperville, IL. https://t.co/ZSQSlxBtXo
My colleague, Alex Picksley from @BerkeleyLab , delivered a fantastic plenary talk on his and the team’s great results on acceleration of 10 GeV class electron beams in a footlong HOFI channel guided laser plasma accelerator. Extremely impressive and a great breakthrough! https://t.co/t3hIJ9uJPH
Compact, reliable plasma-based FELs for research and society have arrived. Sam Barber from the @BerkeleyLab BELLA center presented his team’s amazing results on >1000x FEL gain and stable FEL operation at the #AAC24 meeting. Remarkable progress! https://t.co/4ZSpylhQsu
Lotti Obst-Huebl is an amazing scientist at the @BerkeleyLab BELLA center. She is performing radiobiological studies and is exploring the FLASH effect to fight cancer with compact laser-plasma-driven proton sources. https://t.co/OeqE5MkBNf
Carlos Antós Solanas
😎Hot Single Photons for Secure Quantum Communication😎 Please welcome this week's curator - @AntnSo 🥳 Check out the conversation b/w Carlos & @MySci_PK on Under the Microscope podcast 🇪🇸 @the_ScienceTalk #QuanTour https://t.co/ymIRMRtSWJ
This week I will show a bit of the experimental activity we carry out here on quantum optics and light-matter interaction in the Dep. @fismat_UAM (@UAM_Madrid). Please, follow the department account! We created it this year :)
We are also affiliated to the Nicolas Cabrera Institute for Material Science (@INC_UAM) and the Condensed Matter Physics Institute (@ifimacuam great X account!)
@INC_UAM @ifimacuam This is the lab where we live! Two setups, cryo and room temperature, for the study of different materials and their non-classical light emission! https://t.co/MH3osCpD0v
@INC_UAM @ifimacuam These days we are trying to assemble an open cavity, the idea is to weakly couple cavity photons to hBN defects; if we manage, I will show some pictures! https://t.co/DdvQl9g3dn
@INC_UAM @ifimacuam This research activity is funded by the @QuantERA_EU initiative, our project, @ComphortQ, will implement bright single photon sources to realice FSO-QKD!
@INC_UAM @ifimacuam @QuantERA_EU @ComphortQ We are very happy to collaborate in this consortium with great research groups such as @HeindelTobias @SchneiderQMat @NQOLab , the group of Ruth Oulton in @BristolUni and 2 companies Nanoplus and QLocked
@INC_UAM @ifimacuam @QuantERA_EU @ComphortQ @HeindelTobias @SchneiderQMat @NQOLab @BristolUni Check the website of the COMPHORT (@ComphortQ) project for more info: https://t.co/FGWieJRg6M
I take the chance to advertise a PhD position opening in the group, see pictures below, and please share it and contact me if interested! https://t.co/BBEmO6ojAN
@INC_UAM @ifimacuam Juan (PhD) and Adolfo (TFG student), managed to visualize the mode rings of the open cavity! Having the hBN defects and the cavity effects, we can start playing with cavity QED phenomena :) https://t.co/EJ918bSs1w
Thank you Carlos for an amazing week of science & sharing your life as a scientist in Madrid🇪🇸 Please give @AntnSo a follow🥳 Make sure to check out Carlos's conversation with @MySci_PK on @the_ScienceTalk YouTube channel https://t.co/ymIRMRtSWJ #QuanTour #SUPERquantum #QTorch