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.     

Micro-mechanical behaviors of SMA composite materials under hygro-thermo-elastic strain fields

An analytical procedure to evaluate the behavior of shape memory alloy (SMA) composite under hygrothermal environment is presented. The SMA wires are considered as inclusions embedded in a homogeneous matrix medium of the composite. The inhomogeneity associated with the phase transformation and thermal strains in the SMA wire as well as the hygrothermal strain in the matrix is homogenized using Eshelby’s equivalent inclusion method. In the present work, a similar approach adopted for SMA composites by Marfia and Sacco [Marfia, S., Sacco, E., 2005. Micromechanics and homogenisation of SMA-wire-reinforced materials. J. Appl. Mech. 72 (2), 259–268.] is considered in order to validate the response of SMA composite subjected to thermo-elastic strain field. However, in the present approach, certain modifications and new derivations for the inelastic strain tensors is carried out. First, the constitutive laws for the SMA wire and matrix are expressed in terms of the average strain in the composite. The evolutionary equations used to characterize the pseudoelastic (PE) behavior of the SMA wire are redefined in terms of the eigen strains (phase transformation and thermal strains) occurring in the SMA wire, which are then expressed in terms of the average strain in the composite. Further, the SMA composite constitutive law under coupled hygro-thermo-elastic strain fields is proposed. The generic homogenized hygric and thermal inelastic composite tensors required for the proposed hygro-thermo-elastic constitutive law are derived. Finally, the SMA composite lamina is characterized using Eshelby’s equivalent inclusion method. Using the proposed modifications and derivations, the analytical results are validated for the case of thermo-elastic strain fields and the procedure is then extended to evaluate the SMA composite behavior under hygro-thermo-elastic strain fields. The results include the effect of thermo-elastic and hygro-thermo-elastic strains on the transformation stresses and the nature of hysteresis due to hygric and thermo-elastic strains.     

Modeling and simulation of first and second sound in solids

We investigate the propagation of mechanical and thermal waves in solids at cryogenic temperatures. The latter are known as the second sound phenomenon. It occurs, e.g., in dielectric solids and differs greatly from the classical case in which the heat transport proceeds by diffusion. Since Fourier’s law of heat conduction fails for modeling second sound, we apply a non-classical one. During the last two decades, the non-classical thermoelastodynamic theory of Green and Naghdi enjoys steadily growing research activities.     

Quantum dynamics of single-photon detection

Dynamics of the elementary photoelectric conversion upon interaction of a single-photon mode with a bound electron in a one-dimensional rectangular potential well is considered. The spatial and temporal dynamics of the wave packet corresponding to a free photoelectron is investigated.     

Thermoelastoplastic deformation of a thick-walled cylinder with a radial crack

The thermoelastoplastic fracture mechanics problem of a thick-walled cylinder subjected to internal pressure and a nonuniform temperature field is solved by the method of elastic solutions combined with the finite-element method. The correctness of the solution is provided by using the Barenblatt crack model, in which the stress and strain fields are regular. The elastoplastic problem of a cracked cylinder subjected to internal pressure and a nonuniform temperature field are solved. The calculation results are compared with available data. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 173–183, May–June, 2008.     

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.