September 2008 Archives

Professor A. Cupane (University of Palermo, Italy) and his colleagues at the European Synchrotron Radiation Facility (ESRF) recently established a method for structural dynamics. The technique uses wide-angle X-ray scattering and images proteins in their natural, fast-moving state. The research group succeeded in capturing the tertiary and quaternary conformational changes of human hemoglobin in close to physiological conditions triggered by laser-induced ligand photolysis. The time resolution of the observation is in the order of nsec. The whole process lasts 3 μsec, and the molecule changes from a "relaxed" form that can bond to oxygen, to a "tense" form that squeezes out the oxygen. They also reported data on optically induced tertiary relaxations of myoglobin and refolding of cytochrome c. For more information, see the paper, "Tracking the structural dynamics of proteins in solution using time-resolved wide-angle X-ray scattering", M. Cammarata et al., Nature Methods, published online, 21 September 2008, doi:10.1038/nmeth.1255

It is well known that nanoparticles often enhance catalytic activity. However, it is still an open question as to whether the metallic or the oxidized state of the particle is the catalytically more active phase. It is therefore significant to study the oxidation/reduction process of metallic nanoparticles. A group led by Professor H. Dosh (Max-Planck-Institut für Metallforschung, Germany) recently reported on some very interesting XRD and GISAXS studies on the oxygen-induced shape transformation of Rh nanoparticles. The experiments were done in-situ, during the oxidation/reduction cycle at high temperature. The group found that shape transformation is driven by the formation of a surface oxide O-Rh-O trilayer, which can stabilize Rh nanoparticles with low-index facets. For more information, see the paper, "Shape Changes of Supported Rh Nanoparticles During Oxidation and Reduction Cycles", P. Nolte et al., Science, 321, 1654-1658 (2008).

The J-PARC (Japan Proton Accelerator Research Complex, Tokai, Japan) is a new facility with MW-class high power proton beams at both 3 GeV and 50 GeV. At the end of May 2008, the first neutron was produced successfully by proton-beam induced spallation reaction at the Materials and Life Science Experimental Facility (MLF). Furthermore, very recently, the facility succeeded in commissioning high-power operation. Its 3-GeV rapid cycling synchrotron (RCS) is said to have achieved a beam power of 210 kW for a period of 70 seconds at 25Hz, and 315kW-equivalent power in one-pulse operation. For more information, visit the Web page, http://j-parc.jp/index-e.html