On the role of branched-chain (autocatalytic) reactions in the carbonaceous feedstock pyrolysis kinetics at oscillating temperature

A kinetic model of flash pyrolysis as a branched-chain process was presented. It was shown that, under unsteady temperature conditions, the branched-chain process significantly enhances carbonaceous feedstock processing.     

Plane stress state problems for notched bodies whose plastic properties depend on the form of the stress state

We consider one possible approach to the problem of describing the dependence of material plastic strain characteristics on the stress hydrostatic component arising in many porous, fractured, and other inhomogeneous materials. The plastic strain of the media under study is investigated under the plasticity assumption in the corresponding generalized form with the use of the form parameter of the stress state. The plasticity constitutive relations are stated on the basis of the plastic flow law associated with the accepted plasticity condition. For the conditions of plane stress state in the framework of the material rigid-plastic model, a system of partial differential equations is obtained and conditions for its hyperbolicity are determined. The relations for determining the stress fields and velocity fields in plastic domains are obtained, and their properties are investigated. The problem of tension of a strip with symmetric angular notches is solved, where the stress fields are determined and the continuous displacement rate field is constructed. The problem of uniform symmetric tension of a plane with a circular hole is considered. The stress fields in a strip with symmetric circular notches are examined. A comparison with solutions for plastically incompressible media whose properties are invariant with respect to the form of the stress state is performed.     

A multilevel Cartesian non-uniform grid time domain algorithm

A multilevel Cartesian non-uniform grid time domain algorithm (CNGTDA) is introduced to rapidly compute transient wave fields radiated by time dependent three-dimensional source constellations. CNGTDA leverages the observation that transient wave fields generated by temporally bandlimited and spatially confined source constellations can be recovered via interpolation from appropriately delay- and amplitude-compensated field samples. This property is used in conjunction with a multilevel scheme, in which the computational domain is hierarchically decomposed into subdomains with sparse non-uniform grids used to obtain the fields. For both surface and volumetric source distributions, the computational cost of CNGTDA to compute the transient field at N_s observation locations from N_s collocated sources for N_t discrete time instances scales as O(N_tN_slogN_s) and O(N_tN_slog²N_s) in the low- and high-frequency regimes, respectively. Coupled with marching-on-in-time (MOT) time domain integral equations, CNGTDA can facilitate efficient analysis of large scale time domain electromagnetic and acoustic problems.     

Polarization switching in heterophase nanostructures: PLZT relaxor ceramics

The polarization switching is experimentally investigated in hot-pressed PLZT-x/65/35 ceramics with a lanthanum content from 5 to 12 at. %. The specific features in the temperature dependence of the polarization switching in a heterophase state are interpreted by analyzing the change in the switched charge measured over wide ranges of fields and temperatures. Particular emphasis is placed on the role of depolarization fields induced by interphase boundaries. A model of the evolution of polydomain nanostructures with a change in the temperature and in the response to an external field is considered. It is assumed that the low-temperature dielectric anomaly and the temperature hysteresis are associated with the loss of stability of a large-scale domain structure and its transformation into a nanodomain state.     

Influence of the stress field of a tilt boundary on a Frank-Read source generating dislocations under the action of ultrasound

The influence of a nonuniform field of internal stresses and the generation of a dislocation loop by a Frank-Read source operating under the action of an alternating load is investigated by computer simulation. It is shown that the field of a tilt boundary affects every stage of development of a dislocation loop until its closure. The influence of the boundary field is determined by the ratio between the length of the source and the space scale of the field nonuniformities. It is established that not only the value of the dynamic yield point but also the form of its dependence on the ultrasonic frequency can vary in an internal stress field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 35–39, February, 1985.     

The Influence of CNT Network Functionalization in Gaseous Media CL2, NO2, O3 on Their Electrical Properties

Russian Physics Journal -     

Structure and biological properties of sodium and potassium 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionates

Sodium (1) and potassium (2) 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionates form crystal hydrates, which exist as both monomers and dimers. Quantum-chemical calculations in the PM6 approximation are used to determined the enthalpies of formation ?H _f ^po , thermal enthalpy H ^po, and entropy S ^po of the monomers and dimers, which are indicative of the possibility of existence of the dimers of propionates of alkali metals. The biological activity of these compounds in animal and plants is demonstrated to be dependent on their concentrations. Compounds 1 and 2 turned out to be efficient in the treatment of burn injuries, cancer, and radiation damage (in vivo and in vitro), as well as in promoting the growth of cereal plants.