82 research outputs found
Rapid fire railguns powered by pulsed MHD generators using plasma-generating solid propellants
Hydrogen-induced sp2-sp3 rehybridization in epitaxial silicene
We report on the hydrogenation of (3×3)/(4×4) silicene epitaxially grown on Ag(111) studied by in situ Raman spectroscopy and state-of-the-art ab initio calculations. Our results demonstrate that hydrogenation of (3×3)/(4×4) silicene leads to the formation of two different atomic structures which exhibit distinct spectral vibrational modes. Raman selection rules clearly show that the Si atoms undergo a rehybridization in both cases from a mixed sp2-sp3 to a dominating sp3 state increasing the distance between the two silicene sublattices. This results in a softening of the in-plane and a stiffening of the out-of-plane phonon modes. Nevertheless, hydrogenated epitaxial silicene retains a two-dimensional nature and hence can be considered as epitaxial silicane. The level of hydrogenation can be determined by the intensity ratio of the Raman modes with different symmetries. © 2017 American Physical Society
Study of thermal effects of silicate-containing hydroxyapatites
The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 °С that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state
Cartographie des effects ultérieurs des tremblements de terre catastrophiques et estimation du risque pour la construction d'ouvrages d'art
Microstructure and Wear Resistance of Detonation Coatings Obtained from Titanium Carbide–Nichrome SHS Powders Having Different Particle Sizes
Non-equilibrium carbothermic reduction of magnesium at the treatment of agglomerated particles “magnesium oxide–carbon” in the plasma jet
Les glissements de terrains et les effondrements dans les regions seismiques leur prediction
Plasma processing and deposition of powdered metal oxides consisting of hollow spherical particles
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