INTERNATIONAL REPORTS American Crystallographic Association „ACA… James A. Kaduk Department of Biological, Chemical, and Physical Sciences Illinois Institute of Technology Chicago, IL 60616 USA
[email protected]
This paper is necessarily highly idiosyncratic. With four parallel sessions of exciting science going on all the time, it is impossible for any one person to cover it all. Crystallographers apparently like to come to Chicago; the attendance of 960 was among the largest. Among the workshops held on Saturday, 24 July 2010 was one for K-12 teachers, on “Crystallography World of Wonders.” The goal of the workshop was to give participants an appreciation of structure and to illuminate basic crystallographic concepts and how they relate to structural pictures used in science classes. Claudia Rawn described the Materials Discovery Camp at ORNL and led the teachers in building crystal structures from Lego blocks, ping-pong balls, and yarn. The teachers took materials back home for use in their classrooms. Cora Lind covered diffraction basics, and Katherine Kantardjieff showed that remotely enabled instruments are a new paradigm for teaching crystallographic science. Jim Kaduk showed how powder diffraction could yield understanding of everyday materials—including chocolate sandwich cookies, peanut butter, wine, cleaning products, rust, plaster, rocks, broken soup bowls, teeth 共and fillings兲, pharmaceuticals, and a deer attractant. Colin Groom and David Goodsell showed how to use the Cambridge Structural Database and the Protein Data Bank, respectively, in the classroom. John Spence presented the first femtosecond protein nanocrystal X-ray patterns from the LCLS, the world’s first hard X-ray laser. Now the challenge is to interpret the millions of patterns that will be generated! Session 07.02, Nonambient Environments for Specialized Experiments, included talks on ultrafast in situ powder diffraction studies, the structural behavior of 共Mg, Fe兲共Si, Al兲O3 perovskite at lower mantle pressures, the high-pressure behavior of H2SO4 and MgSO4 hydrates, medical gases absorbed in metalorganic frameworks, the XIPHOS diffraction facility at the University of Durham, and the multiple high-pressure studies of porous materials. Session 07.05, Local Structure, included PDF and diffuse scattering studies individually and in combination with Rietveld refinements and density-functional calculations. Session 07.09 共organized by Joseph Orgel兲 concerned fiber diffraction studies of Fibril-Forming Pathological Peptides: Prions, Amyloids and “Friends.” More fiber diffraction was reported in Session 03.01, New Developments in Fiber Diffraction: Cryo-Micro-Diffraction and Complementary Techniques. Session 07.16 共organized by Ashfia Huq兲, What Can Your Beamline Do For You?, highlighted the capabilities of a number of national user facility beamlines. 94
Powder Diffraction 26 共1兲, March 2011
To celebrate his long, productive, and continuing scientific career 共as well as his 80th birthday兲, Jim Ibers gave a plenary lecture on 26 July. His lecture Uranium and Neptunium Solid-State Compounds: Adventures in Synthesis, Crystallography, and Characterization discussed the challenges and rewards of studying such compounds. The structural results are only as good as the model; one must bear in mind that assumptions such as kinematic diffraction, known scattering factors, isotropic extinction, and harmonic vibration models may be approximations, and experimental errors are always present. This lecture was followed by the Transactions Symposium, The First Element: In Memory of Bob Bau, in which the power of neutron diffraction to quantify hydrogens in materials was amply demonstrated. The proceedings of this symposium will appear on the American Crystallographic Association 共ACA兲 website. The 2010 ACA meeting will be especially memorable because all three winners of the 2009 Nobel Prize in Chemistry—Venki Ramakrishnan, Tom Steitz, and Ada Yonath—attended and gave plenary lectures on their work on the structure of the ribosome. Session 07.13, Weird Materials, was organized to include materials that did not fit into another topical session. Talks included ones by Jeff Lynn on spin ice and magnetic monopoles, Marcus Bond and Louise Daw on unusual copper 共II兲 complexes, Jim Kaduk on what to do when your data are too good, Christine Beavers on simple projects that became complicated, and Abe Clearfield on the selective ion exchange material Na2Ti3O3共SiO4兲共H2O兲2. Session 07.14, Functional Materials, included presentations on CMR materials 共Omar Chmaissem兲, Zn and Sn substitution in In2O3 共Cathleen Hoel兲, P doping in Fe-based oxypnictides 共Clarina dela Cruz兲, new materials 共Ken Poeppelmeier兲, functionalized nanoparticles as a medium for studies of photosensitizer dyes 共Jason Benedict兲, and local structure and properties of “ReO3” type frameworks 共Angus Wilkinson兲. Probably not many people bounced between the simultaneous sessions on synchrotrons in molecular biology and incommensurate and modulated structures, but these parallel sessions made for an exciting Wednesday morning for me. Wednesday afternoon’s session on Energy-Related Materials included presentations on coordination polymers, metalorganic frameworks such as CO2 capture materials, methane and hydrogen storage materials, proton conductors, magnetic refrigeration materials, magnetoelectrics, and thermoelectrics.
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Session 07.24, Mechanisms in Phase Transitions, highlighted the growing use of 共and new tools for兲 symmetry mode analysis in understanding phase transitions. Session 07.25, Powder Diffraction, included talks on twodimensional diffraction 共Bob He兲, symmetry detection by symmetry mode analysis 共Branton Campbell兲, synchrotron studies of alkali-metal phenolates 共Matthew Suchomel兲, pressure-induced switching in magnetic framework materials 共Gregory Halder兲, extending the power of PowSnB 共Hongliang Xu兲, and charge flipping studies of metal-organic
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frameworks 共Fernando Uribe-Romo兲. There were ⬎330 poster presentations, which I will not attempt to summarize. The Materials, Powder, and Neutron Special Interest Groups had their usual joint meeting, which resulted in a continuous “materials track” of sessions through the whole of the 2011 ACA meeting in New Orleans. The ACA meeting is not just about structural biology! There is more than enough to keep a materials scientist busy the whole meeting.
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