Results 1 - 10 of 38107
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[en] The aim of this study was to make a correct model of an elementary MSR cell calculated by HELIOS. Infinite multiplication factor and temperature coefficient of reactivity were calculated for various fuel channel diameters (Authors)
[en] We study Mordell-Weil lattices for non-hyperelliptic fibrations on surfaces with zero geometric genus and irregularity. We prove theorems on the structure and uniqueness of such lattices in the maximal case
[en] Many supramolecular complexes form crystals that have lattice constants of the order of 1000 Å. An optimized method for data collection and processing is described. Studies of icosahedral virus capsids provide insights into the function of supramolecular machines. Virus capsid crystals have exceptionally large unit cells; as a result, they diffract weakly compared with protein crystals. HK97 is a dsDNA lambda-like bacteriophage whose 13 MDa capsid expands from 550 Å to 650 Å with large subunit conformational changes during virus maturation. The HK97 penultimate maturation intermediate was crystallized in a tetragonal unit cell that has lattice constants of 1010 Å × 1010 Å × 730 Å. The crystals could be cryoprotected, but diffracted to a modest resolution of 5 Å at a bending-magnet beamline. When these crystals were optimally exposed with two orders-of-magnitude more photons from a new insertion-device beamline, data extending to better than 3.8 Å resolution were obtained. Here, the strategies to collect and process such data are described. These strategies can be adapted for other crystals with large unit cells and for microcrystals
[en] The crystal structure of aragonite (a=4.9611(4), b=7.9672(6), c=5.7407(4) A, cell content: 4xCaCO3, space group: Pmcn) was refined with 1180 neutron diffraction data to Rsub(w)=0.014. The atomic parameters of earlier X-ray refinements were essentially confirmed, but were now determined with considerably higher accuracy. The aplanarity of the carbonate group is 0.0280(5) A, a value greater by 0.010 A than that in dolomite. (Author)
[en] We discuss the size-dependent density of nanoparticles and nanostructured materials keeping the recent experimental results in mind. The density is predicted to increase with decreasing size for nanoparticles but it can decrease with size for nanostructured materials that corroborates the experimental results reported in the literature. -- Highlights: ► Density of nanoparticles depends mainly on the size-dependent lattice parameter. ► Density is predicted to increase with decreasing size for nanoparticles. ► Density decreases with size for nanostructured materials.
[en] The structure stabilities and electronic properties of Mg-X (X = Ni, Pd, Ti, Nb) interfaces are studied by first-principles calculations, including the atomic mixture effect. In particular, the Mg-X interface structures are systemically investigated by minimizing the lattice mismatch, including the lattice constants, cell area, and included angle of the lattice (cell shape). It is found that the optimal interface matches are 4:7, 3:4, 7:8, 9:4 in surface cell atom numbers (limited up to 10 in consideration of computational cost) for Mg-Ni, Mg-Pd, Mg-Ti, Mg-Nb, and the corresponding interface energies are −0.01, −0.9, 0.4, 0.9 J m−2, respectively. We find that atomic mixing at the interface affects the strain, and even stablize the interfaces in the large-mismatch cases. Furthermore, exemplified with the Mg-Pd interface, we find the atoms at the interface can be exchanged under practical condition with assitance of vacancies at the interface. (paper)
[en] We have studied the structural and magnetic properties of (Ni1χMgχ)Fe2 O4 ferrite. X-ray diffraction and magnetization measurements were performed for all samples. x-ray results showed that a single phase ferrite was obtained for all samples. The lattice parameter, a, was estimated from the X-ray results and we found that the lattice parameter increases slightly at high Mg2+ contents (χ > 0.4). Magnetic hysteresis measured for all samples showed that the coercivity (Hc) shows an appreciable change at low (χ=0.2) and high (χ=1.0)Mg2+ content. It was also found that the saturation magnetization (Ms) and the reman ece (Mr) decreases with increasing Mg. (authors).