Heterogeneous doping of sulfide-conducting phases based on calcium and barium thiolanthanates

The chemical method of preparation of oxide precursors was used to obtain sulfide-conducting ionic salts of CaY₂S₄, BaSm₂S₄ and heterogeneous additives of ZrS₂ and SiS₂, accordingly. The sintering modes for obtaining the heterogeneous systems of CaY₂S₄–ZrS₂ and BaSm2S4–SiS2 were chosen. Samples were characterized using the methods of X-ray phase analysis and microprobe analysis. The methods of thermogravimetric and differential thermal analysis were used to determine thermal stability of samples. The temperature and concentration dependences of conductivity and average ionic transport numbers were studied. The range of compositions of heterogeneous mixtures is determined in which conductivity considerably exceeds conductivity of the basic sulfide-conducting solid electrolytes.     

Study of “Racemic Compound-Like” Behavior of Diastereomeric Mixture of Pinanyl Sulfoxides by X-Ray Diffraction,IR Spectroscopy,and DFT Calculations

Abstract

The oxidation of a β-hydroxysulfide in the pinane series by use of m-chloroperbenzoic acid resulted in the formation of the corresponding β-hydroxysulfoxide as a mixture of two diastereomers in 4:5 ratio. According to single-crystal X-ray diffraction (XRD) results, it is established that the diastereomeric mixture of sulfoxides crystallizes in the “racemic compound-like” manner under formation of asymmetric dimers through S=O··H–O interactions. This asymmetric dimer formed from diastereomeric molecules is a structural unit in both crystal modifications, the triclinic and the monoclinic one. The behavior of the diastereomeric mixture of pinane derived sulfoxides in crystals, melts and in tetrachloromethane solutions was studied by IR spectroscopy. The density functional theory (DFT) method with 6-31G (d, p) basis set was used to calculate the optimized geometrical parameters and vibrational frequencies of different associates in solutions. The calculated vibrational frequencies are compared with experimental IR spectra.     

High-strength biocompatible hydrogels based on poly(acrylamide) and cellulose: Synthesis, mechanical properties and perspectives for use as artificial cartilage

New composite hydrogels based on cellulose and poly(acrylamide) have been synthesized via radical polymerization of acrylamide in cellulose swollen in a reaction solution. In this study, both a plant form of cellulose and a bacterial form—that cultivated by Acetobacter xylinum bacteria—were used. The behavior of synthesized hydrogels during swelling in water, as well as the behavior of the samples swollen at equilibrium during deformation under uniaxial compression under various test conditions, have been studied. A comparative analysis of the main mechanical characteristics of hydrogels and the appropriate data for various types of articular cartilage, one of which—rabbit knee meniscus—has been tested in this study, has been performed. An average-strength hydrogel is very close to articular cartilage in all mechanical characteristics. The degrees of loading at the highest compression deformations observed during the function of joint cartilage (30–50%) is in the range 4–12 MPa for this hydrogel, and the average values of the compression modulus in the deformation ranges of 10–15 and 25–30% are 8.8 and 23.7 MPa, respectively. The behavior of hydrogels and rabbit meniscus under cyclic compression with the amplitude of 50% has been studied. Hydrogels and meniscus under this test conditions demonstrate clear viscoelastic behavior, evidenced by noticeable hysteresis for the first cycle and a decrease in the value of the maximum load with an increase in the number of cycles. Structural features of hydrogels, which can affect the behavior of the hydrogels under study, have been considered. On the whole, the results demonstrate the possibility of modeling the mechanical behavior of cartilage with the use of hydrogels of this type.     

Reaction of N,N-Dichlorosulfonamides with Ethynyl(trimethyl)silane

Russian Journal of Organic Chemistry - Ethynyl(trimethyl)silane reacted with N,N-dichloroarenesulfonamides to give unstable N-[2,2-di­chloro-2-(trimethylsilyl)ethylidene]arenesulfonamides...     

Synthesis and antiherpetic activity of novel purine conjugates with 7,8-difluoro-3-methyl-3,4-dihydro-2H-1,4-benzoxazine

Chemistry of Heterocyclic Compounds - A method for the synthesis of novel purine conjugates with 7,8-difluoro-3-methyl-3,4-dihydro-2H-1,4-benzoxazine containing fragments of ω-amino acids with...     

Improvement of extreme controls and the steepest ascent method in the norm maximization problem on the reachable set

The maximization of the terminal state norm of a linear system is considered in the sense of searching for and improving extreme points of the reachable set. A sufficient optimality condition is formulated in terms of a special maximum function. A steepest ascent method for level surfaces of the objective function is constructed, and related procedures for improving extreme controls are described.     

The influence of deuteration on the phase transitions in (NH4)3 Me 3+F6 cryolites (Me 3+=Sc and Ga)

The heat capacity of partially deuterated crystals with a cryolite structure, namely, (NH₄)₃ScF₆ and (NH₄)₃GaF₆, is measured in the temperature range from 80 to 370 K. The p-T phase diagrams of these compounds are investigated at pressures up to p=0.6 GPa. It is revealed that the deuteration does not affect the sequences of phase transitions observed in the proton-containing ammonium cryolites studied earlier. The isotope effect most clearly manifests itself in significant changes in the thermodynamic parameters of the $I12/m1 - P\bar 1$ low-temperature transformation in scandium cryolite.     

Thermoelectrical regime of a vertical electrolyzer. Part 2: Numerical modeling of two-phase electrolyte convection

The results of numerical modeling of two-phase electrolyte thermo-and hydrodynamics in the working space of a separate electrolyzer cell with vertical electrode arrangement are presented. The problem is solved in a self-consistent formulation taking into account the electric current, Joule heat evolution, gas evolution, gas and liquid flows, and electric conductivity of the disperse phase. Within the framework of the proposed two-liquid approach, near-wall bubbly flow is calculated using a model of expanding gas plume, which is based on the introduction of an effective force acting upon the gas phase. The results of several variants of such calculations are compared. The numerical solution is also compared to approximate analytical solutions of the problem. The results of this study can be used to calculate estimations of the electrical and thermal regimes of vertical electrolyzers.