Pressure-Induced Structural Deformations in SeO2

The high-pressure behavior of low-dimensional selenium dioxide SeO₂ (P4₂/mbc, Z=8) is studied with Raman scattering and synchrotron angle-dispersive X-ray powder diffraction in a diamond anvil cell up to 23 GPa at room temperature. Pressure-induced transformations in this material involve a sequence of structural distortions of the chain structure. The transformation occuring above 7.0 GPa is due to symmetry lowering to space group Pbam (Z=8) without major changes of the crystal lattice dimensions and coordination around the Se atoms. Like in the ambient pressure polymorph, the structural unit is a SeO₃E polyhedron, where E is a Se non-bonded electron lone pair, or an irregular tetrahedron with the O atoms and Se lone pair at the vertices. Further structural transitions above 17 GPa are likely to be the result of additional distortions leading to monoclinic symmetry of the crystal structure. All transformations are reversible with little hysteresis.     

Mathematical Models for Metal Matrix Composites Manufacturing

Infiltration by a pure liquid metal into a rigid preform in the presence of partial solidification is analyzed. The mathematical model which is developed takes into account the coupling between the flow through the porous medium and the thermal effects. The model has a two-scale formulation: phase change occurs at the microscopic scale, while macroscopic flow and heat transfer involve large scale quantities.     

Solvation of 1-butyl-3-methylimidazolium hexafluorophosphate in aqueous ethanol--a green solution for dissolving 'hydrophobic' ionic liquids

The relatively hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate has been found to be totally miscible with aqueous ethanol between 0.5 and 0.9 mol fraction ethanol, whereas the ionic liquid is only partially miscible with either pure water or absolute ethanol; the ability to dissolve 1-butyl-3-methylimidazolium hexafluorophosphate in a 'green' aqueous solvent system has important implications for cleaning, purification, and separations using ionic liquids.     

Reaction of 2,3-dihydro-4-phenyl-1H-1,5-benzodiazepinethione-2 with acetylhydrazine

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, p. 1430, October, 1991.     

Relativistic electromagnetic solitons in the electron-ion plasma

We present the results of the investigation about the ion motion influence on relativistic soliton structure, and show that in the case of moving multinode solitons the effect of the ion dynamics results in the limiting of its amplitude. The constraint on the maximum amplitude corresponds to either the ion motion breaking in the low-node-number case, or to the electron trajectory self-intersection in the case of high-node-number solitons. The soliton breaking leads to the generation of fast ions, and provides a novel mechanism for the ion acceleration in the plasma irradiated by the high-intensity laser pulses.     

Particle Creation in a Robertson–Walker Universe Revisited

We reanalyze the problem of particle creation in a 3+1 spatially closed Robertson–Walker space-time. We compute the total number of particles produced by this non-stationary gravitational background as well as the corresponding total energy and find a slight discrepancy between our results and those recently obtained in the literature (Setare, M.R. in Int. J. Theor. Phys. 43:2237, 2004).