Simulation of variations in mechanical properties of polyurethane elastomers modified with carbon nanotubes

The addition of extremely small portions of single-wall carbon nanotubes causes an anomalous change in mechanical properties of a cross-linked polyurethane-amide-urea elastomer containing 10% of polyamide-6; namely, with a nanofiller content of hundredths and thousandths of a percent, local maxima of elastic modulus and ultimate stress are observed. In the work, the anomalous variation in the elastic modulus is simulated relying on the concept of intermediate phase layer formation at the boundary of contacting particles of the initial material.     

Some coercive problems for the system of Poisson equations

In the paper, two boundary value problems for the system of Poisson equations in three-dimensional domains are studied.     

Electrical and magnetoresistive properties of nanogranular CoFeB-CaF2

The electrical properties and magnetoresistance of (Co₄₁Fe₃₉B₂₀) _x (CaF₂)_{100 ? x} composite are investigated. The principal mechanisms of electric charge transfer at low temperatures are determined. The effective density of localized states at the Fermi level and the average number of localized states between adjacent granules at various concentrations of the metal phase are estimated.     

Properties of MnSb/GaAs heterostructures

MnSb layers are deposited on GaAs(100) via the laser ablation of Mn and Sb targets. The magnetic field dependences of the transverse Kerr effect display magnetic anisotropy and magnetization jumps. Measurements of the Hall effect reveal a hysteresis loop at temperatures of up to 300 K.     

Describing weak leptonic processes on the basis of currents with complex coupling constants

Cross sections of elastic (anti)neutrino-electron scattering and neutrino annihilation of an electron-positron pair are obtained and analyzed based on the interaction between diagonal neutral currents and complex or purely imaginary coupling constants.     

New experimental data on the 10B(n, αt)4He reaction

A new technique is described that makes it possible to detect reaction products with the escape of charged particles occurring on components of working gas under the action of fast neutrons. This technique is unique since it offers the possibility of studying reactions for which more than two charged particles are generated in an output channel. This work studies interactions between neutrons and ¹⁰B nuclei, where two α-particles and tritium nucleus are produced as reaction products.     

Probabilities of delayed processes for nuclei involved in the r-process

Delayed fission, along with induced and spontaneous fission, is responsible for the suppression of the production of superheavy elements both during the r-process and after its completion. Beta-decay strength functions are required for calculating delayed fission. In the present study, respective strength functions are calculated by relying on the theory of finite Fermi systems and by predominantly employing nuclear masses and fission barriers predicted by a generalized Thomas-Fermi model. The probabilities for delayed fission and for the emission of delayed neutrons are calculated for a number of isotopes. On the basis of calculations performed in order to determine the probabilities for delayed processes, it is shown that some of the delayed-fission probabilities calculated thus far were substantially overestimated. The application of these new results to calculating the r-process may change substantially both the r-process path and the yields of superheavy nuclei.     

Studies of concentration and temperature dependences of precipitation kinetics in iron-copper alloys using kinetic Monte Carlo and stochastic statistical simulations

The previously developed ab initio model and the kinetic Monte Carlo method (KMCM) are used to simulate precipitation in a number of iron-copper alloys with different copper concentrations x and temperatures T. The same simulations are also made using an improved version of the previously suggested stochastic statistical method (SSM). The results obtained enable us to make a number of general conclusions about the dependences of the decomposition kinetics in Fe-Cu alloys on x and T. We also show that the SSM usually describes the precipitation kinetics in good agreement with the KMCM, and using the SSM in conjunction with the KMCM allows extending the KMC simulations to the longer evolution times. The results of simulations seem to agree with available experimental data for Fe-Cu alloys within statistical errors of simulations and the scatter of experimental results. Comparison of simulation results with experiments for some multicomponent Fe-Cu-based alloys allows making certain conclusions about the influence of alloying elements in these alloys on the precipitation kinetics at different stages of evolution.