Mostly science, some physics teaching
The standard way of studying the structures of crystals on atomic lengthscales, is X-ray diffraction. We fire X-rays at a sample and then detect the X-rays that bounce off the sample, as a function of the angle X-rays come out. This gives us what is called a structure factor, S(k), where k is called the wavector, which has dimensions of inverse length, i.e., m-1.
The biggest news in physics this year was the discovery of gravitational waves a couple months ago. Waves in time-and-space are cool, but they are very weak, the detectors measured a distortion in space of one part in 1021 (or 1 in 1,000,000,000,000,000,000,000). That’s a small effect. On the one hand this is bad, as it made them very very hard to detect; the scientists on the LIGO collaboration must be experimental science ninjas and it still took them decades.
Different crystals have different symmetries and these can be read off from the structure factor. For example, a perfect single crystal with the symmetry called body-centred cubic (bcc) shows, when viewed from one angle, a structure factor with a set of sharp points including six arranged at the corner of a hexagon.
I was in Bristol on Thursday for a surprise 70th birthday party, of a friend a colleague, Bob Evans. About 40 of us waited at a restaurant to surprise him; he thought he was going there for a quiet dinner with his wife and few friends. This was a lot of fun. The next day there was a little symposium in his honour.
Understanding how crystals start to form is tricky. We can’t see how it happens as crystals start off microscopic, it is very sensitive to pretty much every aspect of the experimental set up, and the standard theory (called classical nucleation theory) has basically zero ability to predict anything. So we are a bit stuck. But we don’t have the toughest job around, arguably the most complex, and hardest to understand, thing around is the human body, so perhaps the toughest job belongs to medics and biomedical scientists studying diseases.
Two years ago I wrote a blog post expressing amusement at Altmetric’s top papers for 2013. Now that Altmetric is rating a paper of mine #5 of 13,240 outputs (from the journal publisher and as of time of writing), it is clearly time for me revisit my position on Altmetric. Surely, anything that ranks my collaborators and me that highly must be on to something? Altmetric is software that collects references in the news media, blogs and on twitter, to a research paper, and then both provides links to them, and ranks the paper.
I almost titled this post Daily Mail celebrates work of immigrants shocker but as they have written a pretty accurate article on work I am part of, that would be a bit ungrateful. Yesterday a paper came out in Physical Review Letters that I am really rather proud of, although I made only a small contribution to it. Most of the credit should go to Andrea Fortini, who discovered the effect the paper describes, and to Nacho Martin-Fabiani and Joe Keddie who did the experiments to show that it works in the real world too. Andrea found the effect in computer simulations. We also had help from collaborators in Lyon who made the particles Nacho used.
It is almost always easier to borrow ideas and techniques from other fields than to reinvent them. A PhD student, another academic and I, are studying two competing processes. These are crystallisation into two different crystals, called alpha and gamma, of a small molecule called glycine. The formation of alpha and gamma appear to be mutually exclusive, one or the other forms, not both. Crystallisation is statistical, it is at least partly random, and they are irreversible, once a crystal forms it persists.
Lipitor is a cholesterol-lowering drug sold by the pharma multinational Pfizer. People who want to lower their cholesterol take it every day for years or decades. High cholesterol is a common problem, bacon and cakes are just too tasty, and so the market for drugs like lipitor is absolutely enormous. It has been estimated that over fifteen years, Pfizer made $125 billion from lipitor. That’s a lot of money. I don’t have the figures but presumably a billion plus of that was in the UK (i.e., paid for by the NHS). So if you are a taxpayer even if you haven’t taken it, you’ve paid for it. So I’ve paid for it, but I am also interested in lipitor as I study crystallisation, and like most drugs lipitor tablets contain the drug in crystalline form.
Steel is not pure iron, it contains a small fraction of carbon that transforms the soft pure iron into the much tougher steel. I guess I have known that for a long time. But I have not really thought about how the carbon is incorporated into the crystalline iron. Dissolving salt in liquid water is straightforward. The ions of sodium and chloride just diffuse around in the liquid surrounded by the diffusing molecules of water. This is a liquid solution, a solution of salt in liquid water. Steel is a solid solution, it is carbon dissolved in solid iron.
Chance & Necessity 