Solid Echo in Three-Spin Groups with Arbitrary Constants of Dipole–Dipole Interaction

Applied Magnetic Resonance - The suggested approach allowed us to derive analytical expressions for modeling the shape of solid-echo signal and its time evolution for a system of three-spin groups...     

Dislocation Structure Evolution in Low-Stability States of Solid Solutions of Alloys Under Their Deformation

Russian Physics Journal - The results of a study of the dislocation structure evolution in polycrystals of homogeneous solid solutions in low-stability states in Cu-Mn-based alloys with FCC crystal...     

Properties of nanocomposites based on crosslinked elastomeric polyurethane and ultrasmall additives of single-wall carbon nanotubes

It is shown for the first time that the addition of ultrasmall amounts of single-wall carbon nanotubes leads to a significant increase in the main mechanical characteristics of the crosslinked poly(urethane urea) elastomer. The elastic modulus and the tensile strength pass through maxima as the nanotube concentration is increased from 0 to 0.018 wt %; at a nanotube concentration of 0.002 wt %, the maximum values of the modulus and strength are higher by factors of 2.5 and 1.5, respectively, than the corresponding values for the unfilled polymer. The thermomechanical, spectral, and structural characteristics of nanomodified elastomers are investigated, and possible causes of change in their mechanical parameters are discussed.     

The behavior of crowdions and their complexes in weakly stable states of materials

Using the method of molecular dynamics, both single crowdions and their complexes are investigated in an fccmaterial being in a low-stability state with respect to an external thermal force. The system’s state with single crowdions is shown to be weakly stable, and their complexes therefore present a more favorable interstitial position. It is established that even under moderate external action (thermal activation or propagation of a standing wave) single crowdions form a dumbbell defect. In a low-stability state that is developed in the vicinity of structural-phase transformations, it is the crowdion complexes which represent more stable configurations. In addition, the bulk crowdion complex appears to be most favorable, being virtually unaffected by the phonon friction.     

Bioconversion of D-glucose in heavy water: Effect of water isotopomeric composition on deuterium fragment distribution in ethanol

The relative distribution of deuterium between methyl and methylene groups in ethanol at the bioconversion of D-glucose in heavy water was studied.     

Kinetics of a bimolecular chemical reaction in the liquid phase with association of both reactants

Mathematical modeling of a bimolecular chemical reaction in the liquid phase was carried out taking account of association of both reactants. The formally simple chemical reaction is thus transformed into a multistage process, which results in the formation of temporal dissipative structures. It was found that, apart from the usual dynamic modes, there appear oscillations of the concentrations of intermediates, characterized by two considerably differing periods.     

Features of the kinetics of chemical reactions in a nanostructured liquid

A review of the literature on the supramolecular structure of a liquid medium and the kinetics of formation of the structure has been presented. The models that relate the kinetics of chemical reactions to the liquid medium structure have been discussed. It has been shown that the results of the mathematical modeling of the kinetics of reactions in a nanostructured liquid medium taking into account the difference in the reactivity of molecules of the reagents and associates are consistent with the experimental data; in particular, they can be used to explain the cause of the observed kinetic anomalies.     

Mathematical Simulation of Low-Frequency Mechanical Action on Bimolecular Reaction Kinetics in a Structured Liquid

A mathematical model of the physicochemical processes that occur under low-frequency mechanical action on bimolecular reaction kinetics with consideration for the association of reagents is presented. As a result of the mathematical simulation, special features of the kinetics and stability of the reaction modes were established. It was shown that, in a structured liquid, a formally simple reaction occurs as a complex process with the appearance of bistability regimes, the formation of a temporal dissipative structure, and the complex structure of intermediate concentration oscillations. The possibility of controlling transitions from stable to unstable reaction conditions and vice versa under changes in the external action amplitude was demonstrated.