Numerical Analysis of the Boundary-Value Problem for a Nonlinear Korteweg–De Vries–Burgers Equation

The paper presents the results of a numerical analysis of the boundary-value problem for a nonlinear Korteweg–de Vries–Burgers equation with two small parameters at the high-order derivatives. An approximation of higher order of accuracy is used to construct an iterative difference spline scheme and to obtain a numerical solution of the third-order equation subject to certain relationships between the two small parameters and the space and time increments. The behavior of the solution of the boundary-value problem is investigated for various parameters at the second and third derivative and for various time and space increments of the difference grid. The interaction of the solution of the degenerate problem (without the third derivative) with the solution of the equation containing two small parameters is investigated numerically.     

Copper in Cross-Coupling Reactions: I. Sonogashira-Hagihara Reaction

Russian Journal of Organic Chemistry - The review addresses the problem of using copper catalysts in the palladium-free version of the Sonogashira-Hagihara reaction. Particular attention is paid to...     

Gd-doped SrTi<Subscript>0.5</Subscript>Fe<Subscript>0.5</Subscript>O<Subscript>3–δ</Subscript> mixed ionic-electronic conductors: structural,thermal, and electrical properties

The effect of Sr by Gd substitution on the structural, thermomechanical, electrical, and electrochemical properties of SrTi_0.5Fe_0.5O_3–δ was investigated in the present work. The powders were synthesized by a solid-state reaction method at 1150 °C with following sintering of the ceramic samples at 1350 °C. The unit cell parameters of the sintered Sr_1–x Gd _x Ti_0.5Fe_0.5O_3–δ (x = 0–0.4) ceramics were found to decrease with a gradual increase in Gd content, and a change in the crystal symmetry from cubic to tetragonal at x ≥ 0.1 was observed. It was found that the Gd doping enhanced the stability of the ceramic samples in a reducing atmosphere and reduced the thermal expansion coefficient value. Gd doping in the amount of 5 mol% can be used for long-term stabilization of the SrTi_0.5Fe_0.5O_3–δ material’s conductivity in reducing atmospheres with no significant alteration to the transport properties and oxygen permeability.     

Arylation of Adamantanamines: X. Palladium- and Copper-Catalyzed Heteroarylation of Adamantane-Containing Amines with Bromopyridines

Russian Journal of Organic Chemistry - The catalytic efficiencies of palladium(0) and copper(I) complexes in the amination of 2-bromopyridine and its fluorine-containing derivatives with...     

Doped (Nd,Ba)FeO3 oxides as potential electrodes for symmetrically designed protonic ceramic electrochemical cells

Journal of Solid State Electrochemistry - The design of new electrode materials with high redox stability has great potential for the fabrication of solid oxide fuel and electrolysis cells having a...     

Electrophysical properties of materials based on BaGdCo2O5 + δ

The phase composition, linear thermal expansion coefficient, electroconductivity (in the temperature interval 600–900°C and partial pressures of oxygen 10⁻⁵–0.21 atm) of solid-oxide materials based on gadolinium-barium cobaltite doped with 3d-elements BaGdCo_{2 − x} Me _x O_{5 + δ}, Me = Cu, Fe; x = 0.0, 0.2, …, 2.0 were investigated. The homogeneity regions of samples were established by means of X-ray phase analysis. It was shown that the linear thermal expansion coefficient of cobaltite decreases with an increase in the copper or iron concentration. It was established that the electroconductivity of BaGdCo_{2 − x} Me _x O_{5 + δ} decreases with an increase in x. We concluded that upon a decrease in p(O₂), the electroconductivity of samples first decreases and then reaches a horizontal plateau.     

Structural Changes in С36 Laves Phase Intermetallic Compound TiCr2 During Hydrogenation–Dehydrogenation Process

Russian Physics Journal - The paper deals with melting of titanium and chromium metal powders in plasma of abnormal glow discharge which results in the formation of the hexagonal С36 Laves...     

Structural and electric properties of the Ce0.8(Sm1 ? xCax)0.2O2 ? δ system (x = 0.0–1.0)

CeO₂-based solid solutions with a fluorite structure are promising materials as electrolytes of medium-temperature electrochemical devices. This work presents the results of systematic studies of structural and electric properties and oxygen nonstoichiometry of the Ce_0.8(Sm_{1 − x} Ca _x )_0.2O_{2 − δ} system in a wide range of concentrations of 0 < x < 1 performed in order to establish the causes affecting the system conductivity and its behavior in a reducing medium. It is found that a single-phase solid solution of the fluorite type is formed in the whole concentration range. Parameters of its lattice cells decrease linearly at an increase in the concentration of Ca²⁺. Conductivity in air grows when calcium is added due to a decrease in the grain boundary resistance. The maximum conductivity in air was obtained for the composition of Ce_0.8(Sm_0.8Ca_0.2)_0.2O_{2 − δ} and is 13.71 × 10⁻³ S/cm at 873 K. Studies of the dependence of conductivity of the partial pressure of oxygen showed that electron conductivity is observed at a higher oxygen partial pressure at an increase in the temperature and calcium concentration. The critical partial pressure of oxygen ( p_O2 ^* )\left( {p_{O_2 }^* } \right) for the compositions of Ce_0.8(Sm_{1 − x} Ca _x )_0.2O_{2 − δ} with x = 0; 0.2, and 0.5 is 1.83 × 10⁻¹⁶, 1.73 × 10⁻¹³, and 3.63 × 10⁻¹³ atm at 1173 K, respectively, and 2.76 × 10⁻²¹, 5.05 × 10⁻¹⁸, and 1.31 × 10⁻¹⁸ atm at 1023 K.     

Promising membrane materials based on strontium titanate

Electroconductivity of SrTi_1?x Fe _x O_3?δ(x = 0–0.5) specimens was studied by four-probe method. An opportunity was studied to produce hydrogen by high-temperature electrochemical conversion using SrTi_0.5Fe_0.5O_3?δ as the membrane material of the best conductivity. The effective ambipolar conductivity values calculated for SrTi_0.5Fe_0.5O_3?δ from the leakage experiment were found different from the ambipolar conductivity values calculated by the four-probe data processing because ambipolar conductivity corresponds to bulk transfer of complex oxide particles, taking no surface phenomena into account.     

Copper in Cross-Coupling Reactions: II. Arylation of Thiols

Russian Journal of Organic Chemistry - The review presents an analysis of the recent literature on the use of copper catalysis in the formation of a C-S bond between aryl halides and thiols. The...