12 maio 2014

Dorothy Hodgkins, nobelized and doodled :)

Dorothy Hodgkin photographed in 1947

Dorothy Hodgkin photographed in 1947, the year she was elected to the Royal Society. Photograph: Godfrey Argent Studio, used with permission
2014 has been declared the International Year of Crystallography by Unesco (the United Nations Educational, Scientific and Cultural Organisation). It marks the centenary of the award of the 1914 Nobel Prize in Physics to Max von Laue, swiftly followed the next year by a further Nobel Prize in Physics for the work done by father-and-son team William Henry and William Lawrence (known as Lawrence) Bragg. These two prizes were key staging points in the development of x-ray crystallography, a technique that has done so much to unravel the structure of matter at the atomic level.
Exactly 50 years after the award of the prize to von Laue, Dorothy Hodgkin won the 1964 Nobel Prize in Chemistry for her work in establishing the structures of the vitamin B12 and penicillin, also via x-ray crystallography. During those 50 years the technique had evolved a long way. Initially only metals and compounds containing just one or two types of atom – compounds such as rocksalt (table salt) – could be understood. By the time Hodgkin was working it was possible, if difficult, to analyse huge biological molecules with all their complexity of packing.
Crystallography concerns the study of the regular packing of atoms and molecules in a crystal. Fellow Occam's Corner blogger Stephen Curry has posted videos (here and here) explaining the approach in some detail. In essence, x-rays, with wavelengths much smaller than interatomic spacings, are able to scatter off the atoms in the crystal. Subsequent analysis of the distribution of high intensity spots that makes up the diffraction pattern can then be used to reveal the underlying symmetry. Britain has a long tradition in crystallography, with many famous names (and associated Nobel Prizes) working in this field, including the Bragg father-and-son team and Crick and Watson. There is a genealogy of crystallographers, dating all the way from the two Braggs, passing through the socialist scientist Desmond Bernal to Dorothy Hodgkin and even later Aaron Klug (who won the Nobel Prize in Chemistry in 1982), with Cambridge University, Birkbeck and Kings Colleges and the Royal Institution all playing important roles as host to key experiments.
During the years from the 1930s onwards that Hodgkin was carrying out her research, all analyses had to be carried out without the benefit of computers. This meant that the calculations required to move from a hypothesised model of the crystal packing to a prediction of the resulting diffraction pattern had to be carried out laboriously by hand. The larger the molecule, the harder the calculations as the more terms there were to add in. This needed to be an iterative process since if, as was usually the case, the initial hypothesised structure proved not to lead to a diffraction pattern consistent with the experimental evidence, this could mean repeating huge sets of calculations until a good match was found. For a molecule such as insulin – which Hodgkin spent more than 30 years studying on and off – the complexity of the molecule (and hence the calculations), coupled with the experimental challenges of growing large enough single crystals suitable for the x-ray technique, presented formidable challenges. In fact, though it was an aspiration of Hodgkin's to unravel its structure from as early in her research career as 1934, its structure defeated even her prodigious skills until 1969, some years after she had already won the Nobel Prize.
Dorothy Hodgkin was one of several women who worked with Bernal in Cambridge and London during the inter-war years. Others included Helen Megaw, Dorothy Wrinch and Olga Kennard (who is still alive). In turn, during Hodgkin's long research life, she supervised or collaborated with a host of other women. Crystallography still seems to have something much closer to gender balance in its teams than many other branches of physics and chemistry, probably significantly facilitated by the way both Bernal and Hodgkin nurtured female talent passing through their laboratories, something that could not be taken for granted among senior scientists. In Hodgkin's case key women who themselves went on to have long and successful scientific careers included Clara Shoemaker (nee Brink), Rita Cornforth (married to the future Nobel Prize winner John Cornforth with whom she collaborated throughout her life), Barbara Low, Cecily Darwin Littleton, Jenny Pickworth Gluster, Eleanor Dodson  and Judith Howard. Of these, the last three are still alive and active. Less successful a scientist, who worked briefly with Hodgkin, was Margaret Roberts, better known to the world as Margaret Thatcher.
Hodgkin was a woman not prepared to let her gender get in the way of her work. When married, but still working under her maiden name of Crowfoot, she presented a key paper at a major meeting at the Royal Society in 1938 when eight months pregnant. Another long-term collaborator, Nobel Prize winner Max Perutz, referred to her appearance at this meeting in his speech at her memorial service: "Dorothy lectured in that state as if it were the most natural thing in the world, without any pretence of trying to be unconventional, which it certainly was at the time."
However, the rest of the world may have been less willing to forget her gender. When, in 1964, she was awarded the Nobel Prize, did the press regard her in the same light as they would a man in the same position? Absolutely not. The Daily Telegraph announced "British woman wins Nobel Prize – £18,750 prize to mother of three". The Daily Mail was even briefer in its headline "Oxford housewife wins Nobel". The Observer in its write-up commented "affable-looking housewife Mrs Hodgkin" had won the prize "for a thoroughly unhousewifely skill: the structure of crystals of great chemical interest".
Dorothy Hodgkin remains the only British woman ever to win one of the Science Nobels. It would be nice to believe that next time a British woman wins a Nobel Prize in Chemistry her domestic status will not be foremost in the journalists' minds.

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