Powerful pulsed neutron sources for research with a pulsed magnetic field

The prospects for neutron investigations into the magnetic properties of condensed matter with the use of powerful pulsed neutron sources [Japan Spallation Neutron Source (JSNS) (Tokai, Japan), TIRAN (Zababakhin All-Russia Research Institute of Technical Physics, Russian Federal Nuclear Center, Snezhinsk, Russia), Large Hadron Collider (LHC) (CERN)] and pulsed magnetic fields are considered. It is demonstrated that the diffraction measurements of the magnetic states induced by a magnetic field of up to 700–1000 kOe can be performed at the TIRAN reactor and the neutron source that can be developed on the basis of the LHC accelerator.     

Temperature factor effect on the structure of the separated flow within a supersonic gas stream

The effect of the temperature factor, that is, the ratio of the body temperature to the freestream stagnation temperature, on the structure of the separated flow formed in the presence of a concave corner in a supersonic stream is studied. The strong influence of the temperature factor on the separation zone length and the flow-generated aerodynamic characteristics is established. It is shown that for fairly large deflection angles this flow cannot be described by free interaction, or triple deck, theory.     

Effect of the incomplete accommodation of the heterogeneous recombination energy on heat fluxes to a quartz surface

Taking both the heterogeneous catalytic processes, including the surface formation of particles with excited internal degrees of freedom, and the processes of multicomponent diffusion and heat transfer in the MESOX apparatus fully into account makes it possible to obtain a recombination coefficient and an accommodation coefficient of the oxygen-atoms-on-quartz recombination energy which are in good agreement with the experimental data. The heterogeneous catalysis model constructed can be used effectively for predicting the heat fluxes to the surface of reentry vehicles on their entry into the Earth’s atmosphere.     

Synthesis and structure of nanocrystalline La0.50Ba0.50MnO3

Nanocrystalline manganite La_0.50Ba_0.50MnO₃ was synthesized by the soft-chemical method. For this purpose, the sol-gel method was modified and improved. A trihydric saturated alcohol, e.g., glycerol, was suggested as a new organic matrix. The crystal structure of the composite was studied by X-ray powder diffraction at room temperature. A La_0.50Ba_0.50MnO₃ powder annealed in air at T = 500°C is characterized by a perovskite-like cubic structure with the unit-cell parameter a = 3.869 Å. The chemical composition of the sample was studied by electron-probe X-ray microanalysis. The La: Ba: Mn cation ratio in the material was 1: 1: 2. The surface topography was examined with a scanning electron microscope. The crystallite size was ～30 nm. The dependence of the crystal structure and the surface topology on the annealing temperature was studied. The high-temperature treatment in air resulted in the growth of larger, micrometer-size, crystallites.     

New sources of “active” halogen bis(dialkylamide)hydrogen dibromobromates, efficient reagents for destruction of ecotoxicants

Bis(dialkylamide)hydrogen dibromobromates were synthesized and their reactivity was investigated in decomposition of diethylphosphonic, diethylphosphoric, and 4-toluenesulfonic acids 4-nitrophenyl esters. The nucleophilic reactivity of a typical α-nucleophile, hypobromite ion, is independent of the source of the active bromine. The cetyltrimethylammonium dibromobromate is a unique reagent for destruction of ecotoxicants. In weakly alkaline media the half-life of 4-nitrophenyl diethylphosphonate did not exceed 6 s at [BrO^?] 0.02 mol l^?1, and the apparent reaction rate compared to water increased ～40-fold. The main factor governing the micellar effects of surfactants is concentrating the substrate in the micellar pseudophase.     

Reactions of 2,2-disubstituted 1,1-dicyanoethenes with β-dimethylaminoacrolein aminal and 3-dimethylamino-1,1,3-trimethoxypropane

A reaction of 2,2-disubstituted 1,1-dicyanoethenes with β-dimethylaminoacrolein aminal and 3-dimethylamino-1,1,3-trimethoxypropane leads to substituted 6,6-dicyano-1-dimethyl-aminohexatrienes and an organic salt containing 1,1,9,9-tetracyano-2,8-diphenylnona-2,4,6,8-tetraenide as the anion and (dimethylaminopropenylidene)dimethylammonium as the cation, on the basis of which new cation-anionic polymethine dyes were obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1639–1643, August, 2008.     

Rare-earth metal 8-hydroxyquinolinate complexes as materials for organic light-emitting diodes

Rare-earth metal 8-hydroxyquinolinates (q) were studied as emission layers for organic light-emitting diodes. Compounds Dyq₃, Tbq₃, and Smq₃ possess weak electroluminescence due to the emission of the ligand, and the electroluminescence of Hoq₃, Tmq₃, and Ybq₃ is due to electronic transitions of the lanthanide ion. The best electroluminescence characteristics were demonstrated by Scq₃ and Yq₃. The power efficiency of the organic light emitter based on ITO/TPD/Scq₃/Yb (ITO is tin-alloyed indium oxide, TPD is N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine) is 2.6 lm W⁻¹ at a luminance of the device of 300 cd m⁻².     

Synthesis of vanadium-phosphorus oxide catalysts deposited onto silica-carbon supports

Effect of conditions of hydrothermal and microwave synthesis of supported vanadium-phosphorus oxide catalysts in an aqueous medium on the physicochemical properties of the vanadyl hydrophosphate obtained was studied. The transformations occurring in the system were examined using X-ray phase and differential-thermal analyses, adsorption-structural method, and scanning electron microscopy.