Amplification of ultrasound by transverse electric current in semiconductors with hot electrons

The possibility of amplification of ultrasound by the transverse electric current (i.e. when the drift of electrons in the direction of sound is absent) in a transverse magnetic field is shown for a semiconductor where the alternating heating of electrons by the sound wave is essential. The physical explanation of this phenomenon is given on the basis of concept of the motion of electron bunches created by the sound wave under the action of crossed electric and magnetic fields.     

On one approach to realization of the branch-and-bound method on a distributed system

The branch-and-bound method is one of most efficient search algorithms. However, parallel decomposition of this method is difficult even on architectures with common memory, not to mention distributed systems. The paper describes an algorithm for solution of the problems that can be solved with the branch-and-bound method on a distributed computer system. The results of testing of the proposed algorithm via solution of the chess-game problem are presented.     

Optimal control of a spacecraft with a solar sail

Analysis of the results indicates that:

Effect of preparation procedure on the properties of CeO2

The effect of preparation procedure on the physicochemical and catalytic properties of CeO₂ was studied. Differences in the electronic and structural characteristics of CeO₂ depending on preparation procedure and treatment temperature were found using X-ray diffraction analysis, transmission electron microscopy, UV-visible electronic spectroscopy, and X-ray photoelectron spectroscopy. With the use of the temperature-programmed reaction with CO, it was demonstrated that CeO₂ samples with a high concentration of point defects—oxygen vacancies caused by the presence of Ce³⁺—were characterized by an increased mobility of bulk oxygen. The samples of CeO₂ with a high concentration of structural defects—micropores of size 1–2 nm and stepwise vicinal faces in crystallites—exhibited a high catalytic activity in the reaction of CO oxidation.     

Detection of afobazole and its major metabolites using capillary gas chromatography-mass spectrometry

The possibility of detecting a target compound using Gas Chromatography-Mass Spectrometry has been demonstrated and the structure of these compounds has been confirmed. The possibility of sorption of these compounds in the chromatographic system has been analyzed. Results obtained using various sample injection modes have been compared. A highly sensitive method for detecting micromolar amounts of the compounds under investigation in samples with large volumes has been developed. The detection limits of the compounds studied equaled 5 × 10^?10 g in a sample of the model solution.     

Spin-injection radiation of terahertz waves in ferromagnetic structures

We propose and discuss the mechanisms of terahertz sd exchange radiation during transmission of the spin-polarized current in a structure from a thin steel rod pressured to an ultrathin ferromagnetic film. The two mechanisms considered are quantum transitions between the quasi-Fermi levels in the film near the rod and precession of injected spins around the film magnetization.     

Current induced exchange switching of magnetic junctions with cubic anisotropy of a free layer

The stability of equilibrium configurations of magnetic junctions with a free layer of cubic anisotropy with two axes in the layer plane has been analyzed. Variants of switching between different configurations have been considered. It has been demonstrated that the possibility exists of considerably decreasing the threshold current density necessary for switching. Numerical simulation of the dynamics of switching between different configurations has been performed.