With the end of the semester approaching and various grant deadlines, it's been a very busy time. Here are some items I spotted this week (some new, some old):
- This article from Quanta about the "Einstein tile" is great - I particularly like the animated illustration. This prompted some fun discussions with colleagues about whether there might be materials with structures like this, and what their properties would be, since they are ordered yet aperiodic yet not quasicrystalline.
- On twitter, I saw a link to this Nature Photonics paper that measures losses in what are designed to be topological photonic structures. The motivation behind such structures is that certain propagating optical modes are expected to be topologically protected from back-scattering. Instead, the authors find plenty of back-scattering, and they raise the question of how useful topological protection is in practice. Thought-provoking.
- Also on twitter, I saw this Nature paper, which uses ultrafast optics to look at Floquet effects with sub-optical-cycle timing resolution.
- Lengthy article in Science about plagiarism and Ranga Dias.
- This article is about making a low-cost (€100) detector for electron microscopy, far cheaper than the hardware supplied by commercial SEM vendors. I reiterate: I think it would have enormous impact if someone could develop an SEM that is truly inexpensive (say less than $2000, so that many high schools and community colleges could afford one).
- I had occasion to re-read the original paper by Little and Parks (1962) on what is now called the Little-Parks effect. The transition temperature (inferred via the resistance in the transition regime) of a thin-walled superconducting cylinder oscillates with external magnetic field threading the cylinder. The oscillations are periodic in magnetic flux with a period \(h/2e\), providing key evidence that the current in superconductors is carried by pairs electrons (or holes). It's cool to see how they made a 1 micron inner-diameter Sn cylinder back before we had all the fancy modern fabrication techniques, reaffirming that GE Varnish is a wonder material.
- SpaceX is going to try to launch their truly enormous rocket this coming week from Boca Chica, TX. Like any first test flight, it has a good chance of failure, but if they can get this system to work as envisioned, it will truly be transformative in terms of payload to orbit. Here's the link to their live webcast that starts Monday morning.
10 comments:
There is a report here that Dias has been suspended by Rochester:
https://tinyurl.com/59ewf3r6
OK... I admit it. You got me.
That’s just mean, Anon.
S/he got me, too. I debated deleting the comment, but that seemed humorless.
There's something to be said about how insane TEM/SEM prices are and how it has set back the field. About 50% of the market for those items is academic. Prices are insanely inflated and all that money is coming from tax payers (especially bad in biology). What makes it worse is the manufacturer black-boxing - microscopists at universities hopelessly accept that they are at the mercy of these companies. In the US, the skills for electron optics are simply lost, virtually no one can build a useful EM themselves anymore even if they wanted to (this is not the case in Germany and Czech Republic).
Been saying this for years, but we honestly need a synchrotron-type user facility for electron microscopes to rebuild that expertise and not sink money into EM manufacturers hoping they'll build what we want (all these companies are foreign anyways, no US builders of TEM/SEMs these days really). Currently, modifying commerical EMs is so expensive and painful that very few people even attempt it. You would give a heart attack to microscopy PIs by even suggesting the word.
Imagine instead if you could put in a proposal for electron microscopes and get as robust results as you get from xray synchrotrons (local crystal structure from electron diffraction, phonon structure with EELS, etc.)? Instead you have to spend a very long time and lot of money training up graduate students to get a specific tool to work and largely reverse engineer it since manufacturers have no interest in helping you do anything outside of the specs.
That’s an interesting suggestion. HHMI’s Janelia Farms has been working on developing instrumentation so they might be one organization to pitch this idea to.
Anon@12:27, it's not really my expertise, but is the National Center for Electron Microscopy at LBNL supposed to function that way?
NCEM did very nice work making two cutting edge transmission electron microscopes and making them available starting about a decade ago (that's right, just TWO). These are swiss army knife machines though, very good at a lot of things, but take years to get skilled at for your expetiment. They are also still heavily constrained by EM manufacturers, but less so than a typical university.
I think scaling up something like NCEM (or Cornell's NSF EM facility) to the synchrotron scale and (1) dedicating machines for certain types of experiments, and (2) nurturing in-house electron optics and customization expertise like synchrotron facilities rather than sitting at the mercy of EM manufacturers. Such a facility would totally change the EM playing field from being tied down to the whims of companies and teaching great students to be afraid of modifying EMs to being proper open science again.
Cf this article about Nobel Laureate Richard Henderson struggles against EM companies.
https://www.science.org/content/article/we-need-people-s-cryo-em-scientists-hope-bring-revolutionary-microscope-masses
@Doug: can you elaborate why the Einstein tile in the quanta articleis not quasiperiodic?
A few thoughts from someone who has run, designed and brought to fruition two electron microscope labs from scratch...
National facilities are a nice idea, but completely fail to support the 'bread and butter' science that a decent FEG-SEM and/or FEG-TEM/STEM, located locally at a university, will be doing. Sure, aberration correctors are great to have, but most interesting materials problem involve lengths scales from nanometres to hundreds of nanometres (usually diffusion-related distances). Even at Oxbridge (with which I am familiar) for every hour of state-of-the-art EM we did, there were two to three hours of basic EM: metrology, defect analysis or EDS analysis. It was often done on a ten-to-fifteen year old FEGSEM/ W-filament TEM pimped up with a decent retro-fit EDS system or digital camera (bought on Professor X's grant that she got a few years ago or university support fund). You'd be amazed how much science is done on legacy instruments. Further, if you watch how people actually use microscopes, they tend to be part of a workflow that involves back-and-forth between a reaction vessel and microscope. It is not uncommon for two or three visits to a microscope as users fine-tune their synthesis. One of the microscopes I was responsible for (a JEOL 200CX) was (in 2016) used to examine about twenty electrochemically polished foils a day. National facilities are useless for this kind of work.
National facilities tend to have the latest instruments ($10M price tags) with monochromators, aberration correctors, pixelated STEM detectors and the like. However, without some basic understanding of what information these instruments can provide (let alone the data handling capabilities), the user base can be *really* thin. You need really good people to make the most of this kind of rich data set (especially in Materials Science). The situation in Structural Biology is a bit different - the microscopy is, conceptually, really easy to execute and understand. The experimental execution has been simplified and automated and the 'user' is now, effectively, a sample prep technician/data collector.
Effectively, there is the 'Missing Middle' - decent facilities with a good FIBSEM, an analytical SEM with EDS (perhaps EBSD) and STEM detectors, and a good STEM with cold FEG for high and low HT work (e.g. 60 and 200 kV). There would be a two or three Support Staff Scientists for training students (undergrads and postgrads), running collaborative projects and doing outreach. They'd be on academic or academic-related permanent contracts and be encouraged to write applications for small grants and provide support for commercial work (usually local businesses).
The price tags are, at first sight, ridiculous. The hardware on a 200kV STEM has not changed in ten years, but the price tag has gone from about $1M to about $4M (especially for the cryoEMs). There is a feeling of 'money for old rope' feeling about this, but when you 'look under the hood' you can see where the investment has gone... the level of automation is now incredible. For cryoEM, the whole experience has been gamified - you could get a twelve year old to run a cryoEM effectively now. To guarantee this level of performance, though, you *cannot* run third party hardware. Speak to engineers of microscopes and they all complain of how 3rd party items create problems for their platforms (usually, the truth is rather different), but the feeling of having to service third party items from (amateurish) engineering firms creates resentment. For some EM manufacturers, they've taken the decision to have everything integrate or not at all. This is the only way they can guarantee operational up times demanded by customers.
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