While studying materials made from DNA-coated nanoparticles, researchers found a new form of this matter: lattices in which smaller particles roam like electrons in metallic bonds.
Tag: chemistry
Beyond Oil Feedstocks
you’d need electrochemical efficiencies of at least 60% and electricity available at 4 cents/kilowatt-hr or better to make these ideas profitable (with the usual 30-year-amortization assumption about the plants themselves). How close are we? Many of the processes are currently in the 40-50% efficiency range, and need further scale-up work: within sight, but not there yet. And renewable electricity costs vary a great deal by region. The best cases are getting down around that figure, though, and continuing to improve. 1 feature of electrochemical synthesis is that it would (as mentioned in the excerpt above) provide a use for the mismatched local excess electrical production that can happen with renewables – it’s storage of energy in chemical bonds as opposed to batteries, flywheels, or what have you. But on the other hand, running a chemical plant 24/7 is by far the most economical way to set things up, so the best solution would be coupling with some steadier source of electricity as well.
ML: Careful What You Wish
I’m not going to stand on the sidelines shouting for a fight, though. This whole episode has (I hope) been instructive, because machine learning is not going away. Nor should it. But since we’re going to use it, we all have to make sure that we’re not kidding ourselves when we do so. The larger our data sets, the better our models – but the larger our data sets, the greater the danger that we don’t understand irrelevant patterns in those numbers that we didn’t intend to be there, patterns which the ML algorithms will seize on in their relentless way and incorporate into their models. I think that the adversarial tests proposed by the UCSF group make a lot of sense, and that machine-learning results that can’t get past them need to be put back in the oven at the very least. Our biggest challenge, given the current state of the ML field, is to avoid covering the landscape with stuff that’s plausible-sounding but quite possibly irrelevant.
New Chemistry, And Its Limits
So I enjoyed this paper very much, but it starts off with a claim that’s worth arguing about: “organic synthesis is still a rate-limiting factor in drug-discovery projects“. Is that true?
It depends on where you’re standing. All the synthetic limitations described above are real, and they keep us from being able to make a lot of molecules that we’d otherwise be cranking out. But (and this is a big point) it’s rarely the case that we medicinal chemists identify a tricky new structure that absolutely has to be made. That sounds odd, but it comes down to our predictive powers, which aren’t so great. We don’t generally draw some wild compound up on the hood sash and say “That’s the one, folks: find a way to make it or die trying”. We never know which is the one, so in the absence of knowing, we make the things that we can make in the ways that we can make them, and honestly, much of the time, we can manage to come up with something.
Quantum backflow
quantum mechanical particles can move in the opposite way to the direction in which they are being pushed. This unique property is known as backflow.
Rust, enemy of Civilization
Hurricanes, earthquakes, tornadoes, tsunamis and other dramatic natural disasters can leave mounds of wreckage in a matter of seconds. Rust is different. It is insidious and slow-moving. It takes years for it to discolor buildings, thin steel pipelines and tankers carrying oil, and weaken bridges to the point of spontaneous collapse. Rust, the oxidation that turns aluminum white, copper green and steel brown, “is costlier than all other natural disasters combined,” amounting in the US alone to $437B a year, which approaches 3% of our nation’s GDP. By comparison, the damage done to property by hurricanes Katrina, Sandy and Andrew was, in 2012 $, $128B, $50B and $44B, respectively.
C8
DuPont and the Chemistry of Deception
A man-made compound that didn’t exist 100 years ago, C8 is in the blood of 99.7% of Americans, as well as in newborn human babies, breast milk, and umbilical cord blood. A growing group of scientists have been tracking the chemical’s spread through the environment, documenting its presence in a wide range of wildlife, including Loggerhead sea turtles, bottlenose dolphins, harbor seals, polar bears, caribou, walruses, bald eagles, lions, tigers, and arctic birds. Although DuPont no longer uses C8, fully removing the chemical from all the bodies of water and bloodstreams it pollutes is now impossible. And, because it is so chemically stable — in fact, as far as scientists can determine, it never breaks down — C8 is expected to remain on the planet well after humans are gone from it.
2021-09-03: C8 effects
For 6 disease categories, the Science Panel concluded that there was a Probable Link to C8 exposure: diagnosed high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer, and pregnancy-induced hypertension.
Boron is a Subdued Element
anthropomorphized illustrations of the chemical elements.
2023-02-12: Where do the elements come from?
Automated synthesis
Towards a much more automated organic chemistry, a series of articles by Derek Lowe.
MIDA complexes have an unusual property: they stick to silica, even when eluted with MeOH/ether. But THF moves them right off. This trick allows something very useful indeed. It’s a universal catch-and-release for organic intermediates. And that, as the paper shows, opens the door to a lot of automated synthesis. The idea, the hope, is that if the field does become modular and mechanized, that it frees us up to do things that we couldn’t do before. Think about biomolecules: if peptides and oligonucleotides still had to be synthesized as if they were huge natural products, by human-wave-attack teams of day-and-night grad students, how far do you think biology would have gotten by now? Synthesizing such things was Nobel-worthy at first, then worth a PhD all by themselves, but now it’s a routine part of everyday work. Organic synthesis is heading down the exact same road
End of synthesis? You must be joking. This is not even close. As I tried (ineffectively) to make clear yesterday, I don’t think that this particular paper is The End. But it’s the first thing I’ve seen that makes me think that there is an end to a lot of traditional organic chemistry.
No software is yet producing “Whoa, look at that” syntheses. But let’s be honest: most humans aren’t, either. The upper reaches of organic synthesis can still produce such things – and the upper stratum of organic chemists can still produce new and starting routes even to less complex molecules. But seeing machine-generated synthesis coming along in its present form just serves to point out that it’s not so much that the machines are encroaching onto human territory, so much as pointing out that some of the human work has gradually become more mechanical.
Chemical transition states
to actually image chemical transition states was long thought impossible. anything we can learn about transition states (and how to make them selectively happier and unhappier) is the key to chemistry as a whole.
Gregor J. Rothfuss 