Effect of the diamagnetic dilution on the magnetic ordering and electrical conductivity in the Co3O2BO3: Ga ludwigite

Single crystals of cobalt ludwigite Co₃O₂BO₃ with diamagnetic substitution of Ga³⁺ ions for a part of the cobalt ions have been grown by the flux method. A detailed investigation of the crystal structure and magnetic properties of the compound has been carried out. A preferred character of the occupation of nonequivalent crystallographic positions by gallium has been revealed. It has been found that the effective magnetic moment and the magnetic ordering temperature are decreased compared to those in the original crystal of the Co₃O₂BO₃ ludwigite. It has been noted that the pronounced magnetic anisotropy observed in the crystallographic ab plane of the original material of the Co₃O₂BO₃ composition disappears in the presence of gallium.     

Magnetic properties of novel FeSe(Te) superconductors

Magnetization studies were carried out for the novel FeSe_1−xTe_x superconductors (0≤x≤1$0\le x\le 1$) to investigate a behavior of the intrinsic magnetic susceptibility χ$\chi$ in the normal state. The magnetic susceptibility was found to increase gradually with Te content. The temperature dependencies of the magnetic susceptibility χ$\chi$ and its anisotropy Δχ=_χ∥−_χ⊥$\mathrm{\Delta }\chi ={\chi }_{\parallel }-{\chi }_{\perp }$ were measured for FeSe in the temperature range 4.2–300 K, and a growth of susceptibility with temperature was revealed. For FeTe a substantial increase of χ$\chi$ under pressure was found. Ab initio calculations of the band structure and magnetic susceptibility have shown, that FeSe_1−xTe_x systems are close to magnetic instability with dominating enhanced spin paramagnetism. The calculated paramagnetic susceptibility exhibits a strong dependence on the unit cell volume V   and especially the height of chalcogen species from the Fe plane. With appropriate values of these parameters the calculations have reproduced the experimental data on χ(T)$\chi (T)$ and χ(P)$\chi (P)$ for FeSe and FeTe, respectively.     

Non‐Ideal Dust Structures in Cryogenic Complex Plasmas

The possibility of the formation of dust structures in cryogenic environment at 4.2‐77 K was proved experimentally in the previous researches of cryogenic complex (dusty) plasma [1–5]. It was revealed from the experiments, among others, that the dust structures with high concentration of dust particles can be formed, in which interparticle distance is comparable with particle size ‐ super dense dusty plasma structures. Such structures had exotic properties such as globular (spherical) form, free boundaries, etc. In the present work new results on the experimental investigations of new phenomenon of spheroidizing ‐ process of the dust structure transition to compact globular shape at cryogenic temperatures ‐ were presented. Possible nature of such phenomenon is discussed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Distribution of a liquid and the effective potential in a bounded system with special geometry

We evaluate the density of the distribution of a liquid bounded by a system of coaxial cylinders with a fixed near-wall potential. The problem is solved in the smooth-inhomogeneity approximation for a near-wall potential of arbitrary type. Based on the obtained solution, we analyze the special case where the near-wall potential is essentially short range and remains constant inside each of the sublayers in its range of action. In this case, we evaluate the effective near-wall potential for which the density distribution is a continuous function in the entire domain.     

Side-chain alkylation of toluene with methanol over zeolite catalysts

Catalytic properties of NaX-type zeolites modified by alkali metal cations under hydrothermal conditions have been studied. The highest process efficiency is obtained for CsNaX catalysts. The effect of operation conditions on the process results was examined.     

On the numerical modelling of the turbulent layer penetration into a stably stratified fluid

The improved numerical models based on the algebraic representations of the Reynolds stresses and fluxes and the use of the differential equation for the transfer of the dispersion of fluctuations of the vertical velocity component are considered for describing the processes of a vertical turbulent exchange in a stably stratified reservoir. Numerical modelling of the penetration of a turbulent layer of a mixed fluid in a linearly stratified medium under the action of constant shear stress is carried out. Computational results agree well with known experimental data and point to a substantial influence of the anisotropy of the flow on its main characteristics.     

Gasification of carbon-bearing raw materials in plasma-arc electric furnace with heater and risk of explosion in syngas mixtures

Saw dust was gasified at combined and separated impact of the heater and arc discharge on the raw material. It is shown that because of combustion of a part of produced syngas in the heater the raw material can be gasified with power inputs reduced by 20–25 % in comparison with plasma gasification. Data on parameters of combustion and detonation of syngas mixtures with oxygen and air at a change in the ratio between fuel components CO and H₂ and between fuel and oxidizer are shown for the first time.     

A note on maximizing the permanent of a positive definite hermitian matrix, given the eigenvalues

As a step toward understanding the unsolved problem of determining how large the permanent of a positive semi-definite matrix can be, given the eigenvalues, we note that a necessary condition for A to be a permanent maximizing matrix is that A commute with its permanental adjoint.     

Spectroscopic calculations of CH bond dissociation energies for ethene, propene, and benzene chlorine derivatives

CH bond dissociation energies have been determined by spectroscopic and quantum-chemical calculations for ethane, propene, and benzene chlorine derivatives. The spectroscopic values of CH bond dissociation energies were obtained from the fundamental absorption bands in an anharmonic approximation using the variation method and the Morse harmonic basis. Quantum-chemical calculations were carried out using the 6-311G(3df,3pd)/B3LYP basis. The resulting tendencies of variation of bond dissociation energies are discussed in relation to changes in the structure of the molecule.     

一水甲酸锂晶体二阶非线性光学系数的理论计算

采用有限场方法和含时耦合微扰方法,在6-31+G*基组水平上并考虑了电子相关效应和色散效应的影响,计算了一水甲酸锂晶体的宏观二阶非线性光学极化率和二阶非线性光学系数。其中非线性光学系数d31和d32与Roberts报道的相符,而另一个系数d33则比文献值大。计算结果还表明,在非共振情况下,电子相关效应对非线性光学极化率的影响远远超过了色散效应,同时表明Roberts报道的非线性光学系数比Singh等人报道的更为合理。