Stereochemical behavior of geminal and vicinal 77Se–13C spin–spin coupling constants studied at the SOPPA(CC2) level taking into account relativistic corrections

A systematic theoretical study of geminal and vicinal ⁷⁷Se–¹³C spin–spin coupling constants in the series of the open‐chain selenides and selenium‐containing heterocycles revealed that relativistic effects play an essential role in the selenium–carbon coupling mechanism, especially when the coupling pathway includes a triple bond, contributing to about 10–15% of their total values and noticeably improving the agreement of the calculated couplings with experiment. Both geminal and vicinal ⁷⁷Se–¹³C spin–spin coupling constants show marked stereochemical behavior as documented by their calculated dihedral angle dependence that could be used as a practical guide in stereochemical studies of organoselenium compounds. Copyright © 2014 John Wiley & Sons, Ltd.     

Relativistic effects of chlorine in 15N NMR chemical shifts of chlorine-containing amines

Russian Journal of Organic Chemistry - Quantum-chemical calculations by DFT method demonstrated that the accounting is necessary of the shielding by chlorine of nitrogen atom in practical...     

Applying the photonuclear technique to fissile materials detection

Application of a photonuclear technique is considered as a nondestructive method for detecting the unauthorized transporting of camouflaged fissile nuclear material in cargo containers. The advantages of the technique (the use of time selection and the analysis of energy distributions of delayed neutrons) are demonstrated. The operating modes of the accelerator were optimized by modeling. A version of a neutron scintillation spectrometer based on a stylbene monocrystal is presented along with its schematic and main parameters.     

Regioselective dehydrobromination reaction of 5-bromo-2-bromomethyl-1,3-thiaselenolane 1,1-dioxide

Russian Chemical Bulletin -     

Similarity of three-dimensional and axisymmetric chemically-nonequilibrium flows in the neighborhood of a plane of symmetry

Three-dimensional chemically-nonequilibrium flow past blunt bodies in the neighborhood of the plane of symmetry is investigated within the framework of viscous shock layer theory. The similarity of three-dimensional and axisymmetric flows, previously established in [1] for a uniform gas, is extended to chemically-nonequilibrium gas flows. It is shown that the problem of determining the heat fluxes and friction stress in the neighborhood of the line of flow divergence can be reduced to the problem of determining these quantities for the axisymmetric body. The validity of the axisymmetric analogy is verified by carrying out numerical calculations for bodies of different shapes re-entering the earth's atmosphere along a gliding trajectory. Various models of surface catalytic activity are considered. The use of similarity relations makes it possible to apply existing programs for calculating axisymmetric flows to the solution of three-dimensional problems.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 115–120, March–April, 1990.     

Birfucation of solutions for convecttve flows of gas heated below in a wide range of pressure differences

Direct numerical modeling based on a net method is used to investigate the convective flow of a viscous compressible gas in a closed square region heated from below. The complete Navier-Stokes equations and some simplified models of the type of Boussinesq equations are used. The influence of the hydrostatic compressibility on the bifurcation of the solutions is investigated. A definition of the Rayleigh number that makes it possible to match results obtained using different models is proposed.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 163–166, May–June, 1993.     

Special misorientations in localized deformation regions in Fe-3%Si alloy single crystals

Extended regions located at an angle of 20° to the rolling plane are observed inside deformation bands in a (110)[001] Fe-3%Si alloy single crystal at a high strain (～60%). These regions were interpreted earlier as shear bands. The lattice orientation in these bands is close to (110)[001], and their habit plane is parallel to the {112} planes of the deformed {111}〈112〉 matrix. The misorientations between the bands and the matrix group around special misorientations Σ9, Σ19a, Σ27a, and Σ33a, which are characterized by close angles of rotation about axis 〈110〉. During primary recrystallization, the (110)[001] grains growing from the bands retain segments of the corresponding special boundaries with the deformed matrix.     

57Fe and 119Sn probe M?ssbauer spectroscopy investigation of perovskite-type double manganite family CaCuxMn7?xO12 (x = 0, 0.15, 3)

CaCu _x Mn_7−x O₁₂ (x = 0, 0.15, 3) manganites were studied by ⁵⁷Fe and ¹¹⁹Sn probe M?ssbauer spectroscopy. It was established that the ⁵⁷Fe and ¹¹⁹Sn probe cations are stabilized in the octahedral positions of the manganite structures by substituting the manganese cations. The magnetic and structure phase transition temperatures of CaMn₇O₁₂ and CaCu_0.15Mn_6.85O₁₂ manganites fell upon the introduction of ⁵⁷Fe probe cations into their structures. It was concluded that intrasublattice Mn⁴⁺-O-Mn⁴⁺ exchange interactions play a noticeable role in the formation of the magnetic structure of CaCu₃Mn₄O₁₂ manganite.     

Abnormalities of the thermal expansion of Bi2Sr2-xLaxCuO6 + δ high-temperature superconductor in the dielectric phase (x ≥ 0.8) and charge ordering in an oxygen sublattice

Abnormal negative thermal expansion of single crystals of high-temperature Bi₂Sr_{2 − x} La _x CuO_{6 + ·} superconductor in the dielectric phase (x ≥ 0.8) was detected at low temperatures. It was established that material shrinkage upon heating occurs at higher temperatures than in superconducting compositions. The anisotropic and nonmonotonous effect of a magnetic field of 3–6 T on the coefficient of thermal expansion was revealed. We attribute these abnormalities to the existence of superstructure charge ordering in the oxygen sublattice.     

Specific features of the structural transformations in La1 − x Ca x Mn0.98 57Fe0.02O3 + δ (x = 0.05−0.50)

The specific features of the structural transformations in La_{1 ? x} Ca _x Mn_0.98 ⁵⁷Fe_0.02O_{3 + δ} (x = 0.05?0.50) at different Ca concentrations have been studied using Mössbauer spectroscopy and X-ray diffraction. Variations of the heat treatment conditions (annealing in vacuum and in air) cause reversible phase transitions. For calcium concentrations to 20%, a whole set of phases with reversible structural transitions, such as PnmaII ? PnmaI ? $R\bar 3c$ , can be obtained using the corresponding heat treatment. The phases are successively suppressed with increasing calcium concentration. The rhombohedral phase is suppressed for x = 0.20. When the Ca concentration exceeds 20%, the PnmaII phase is suppressed; as a result, the PnmaI phase with equal concentrations of Mn⁴⁺ and calcium stable during any heat treatments remains. The specific features of phase formation in the La_{1 ? x} Ca _x Mn_0.98 ⁵⁷Fe_0.02O_{3 + δ} compound doped with calcium and in the basis LaMnO_{3 + δ} compound have been compared.