## The renormalization-group analysis of the ground state of the spin-antiferromagnetic chain

Published in category «Condensed matter physics»

We are interested in the anisotropic spin-1 antiferromagnetic chain. System of particles with an arbitrary «large» spin is described directly from the first principles, based on the symmetry law. The ground state of the one-dimensional s = 1 pseudo-Heisenberg antiferromagnet with single-ion anisotropy is calculated using the renor-malization group analysis. Excitations of the chain in the form of linear spin waves are considered. The excitation spectrum has a gap.

## The Frenkel pairs formation in the silicon under high energy electron and proton irradiation

Published in category «Condensed matter physics»

The analysis of defect formation in silicon is made under the irradiations used for modeling of radiating belts of the Earth. It is shown the occurrence of microareas of silicon single-crystals with high concentration of vacancies in which reactions with formation of divacancy and their complexes with impurity atoms intensively proceed; there is a basic distinction in influence of a proton irradiation.

## Phase transitions in Li[002](K[05]Na[05])[0[[gg]]NbO[3] perovskite determined by powder diffraction of synchrotron radiation

Published in category «Condensed matter physics»

A study of perovskite-like dielectric with high piezoelectric constants is presented. The powder diffraction method was used. As a result a sequence of phase transitions was followed, determining phase transition order. The information on temperature evolution of cell parameters, volume and spontaneous deformation was obtained.

## Far-infrared radiation emission by hot two-dimensional electrons in single CaN/AICaN heterojunction

Published in category «Condensed matter physics»

The spontaneous emission of far-infrared radiation from a single GaN/AlGaN heterojunction under heating of two-dimensional electrons in the lateral electric field is investigated experimentally. Dependence of the hot electron temperature on applied electric field is determined with help of current-voltage characteristic analysis. It is shown that the observed radiation emission is well described in the framework of thermal emission of the hot two-dimensional electrons. Effect of nonequilibrium optical phonon accumulation on the integral intensity of radiation is discussed.

## Electron transport in CVD-grown graphene of centimeter size

Published in category «Condensed matter physics»

We present the results of the experimental study of the electron transport in graphene samples grown by the CVD-technology. The data on the thermopower behavior in such samples are presented for the first time. A brief analysis of the obtained results in comparison with the ones for graphene samples prepared by the scotch-tape method and demonstrating the best properties with respect to practical applications is performed.

## Modification of the energy spectrum parameters under doping in the Bi[2]Sr[2]CaCu[2]О[у] system

Published in category «Condensed matter physics»

We present the results of the quantitative analysis of the temperature and concentration dependences of the thermopower in Bi-based HTSC-samples of Bi2Sr2Ca|_;(YcCu20>, (x = 0 + 0.5) and Bi2Sr2_,cKxCaCu20J, (x = 0 + 0.4) compositions on the basis of three different models of the electron transport. The parameters of the energy spectrum and charge-carrier system in investigated samples were determined and a character of their changes with increasing impurity contents was analyzed. Potassium in the Bi2Sr2....xKxCaCu20;), system is proposed to introduce additional states into the conduction band.

## Longitudinal quantum transport of holes in silicon nanostructures

Published in category «Condensed matter physics»

Authors offer the calculation method to calibrate detectors in radioactive aqueous medium using a computer program — «МСС 3D». First of all radius of sphere with radioactive substance has been calculated. This volume is similar to infinite matter with this substance. Then the calculation time reduction method was presented. As a result the detector response function was obtained and compared with experimental data.

## Validation study of the model to predict heating and vaporization of a liquid droplet

Published in category «Simulation of physical processes»

Validation study is presented of the model that predicts droplet heating and evaporation with the internal temperature gradient and liquid recirculation taken into account. Two evaporating liquids having significantly different evaporation rates (acetone and water) and the range of parameters characterizing ambient atmosphere (temperature, humidity, flow velocity) are considered. Reasonable agreement of measured and predicted droplet temperatures, diameters, sedimentation velocities has been obtained. For water, such an agreement has been demonstrated both for large (1 to 3 mm) and small (0.04 to 0.06 mm) droplets.

## Simulation of droplets collisions in gas-drop jet

Published in category «Simulation of physical processes»

The focus of this work is modelling of droplets collision in turbulent evaporating spray. To predict the collision frequency, two modeling approaches — the O'Rourke's method and the NTC (No Time Counter) method are applied. The Brazier-Smith model is used to predict a possible collision outcome which is either droplet coalescence or grazing collision. The effect of droplet collisions on vapor concentration in turbulent evaporating spray has been demonstrated using the in-house code Fire3D. It has been found that droplet coalescence causes the increase of droplet size which leads to the reduction of the evaporation rate. As a result, neglecting droplet collisions in simulations of a starting spray may cause considerably underestimated vapour concentration along the spray axis.

## Simulation of sputtering of the silicon carbide surface under bombardment by ions and clusters

Published in category «Simulation of physical processes»

Characteristics of sputtering of the cubic silicon carbide (111) surface under low-energy bombardment by Si[N] and C[N]ions and clusters (TV =1 — 60) have been presented. An analysis of the correlations between non-additive increase of the sputtering yields and the features of the collision cascade in the target versus the incident cluster size and energy was carried out.

## The dynamics of permafrost lakes thawing and climate changing

Published in category «Simulation of physical processes»

A model of dynamics of radius of a permafrost lake has been developed from the phase transition theory of Ginzburg — Landau using asymptotical approach. Applicability of the model to the problem of prediction of methane emission out of permafrost to the atmosphere was demonstrated.

## Laser diodes application to photodynamic therapy

Published in category «Experimental technique and devices»

Semiconductor lasers with 665 nm wavelength and optical power of 2 W in continuous mode at room temperature have been developed. Application of GalnP/GaAs quantum well structure and original emitter design allowed to obtain a high temperature and spatiotemporal stability of emission intensity, high lifetime and low noise level. Developed optical devices are highly suitable for application in medical systems to photodynamic therapy.

## A set of field structures with a symmetry plane for electron spectrography

Published in category «Physical electronics»

Electron-optical properties of a family of field structures which are inherent for electron spectrography and developed on the base of Eulerian uniform fields with a symmetry plane have been studied in this paper. This potential set under question was constructed using the Donkin's potentials which were conic ones generalized. The various operating modes of spectrograph in the process of particles motion in the symmetry plane were investigated. Afterwards the potential structure defined in the plane was restored into space using the algorithm worked out by the authors. The prospects for electron spectrographs based on these potential structures were analyzed.

## The diffraction of light by ultrasonic waves near the optical axis of gyrotropic crystal

Published in category «Physical optics»

The general solution for acoustooptic diffraction in anisotropic and gyrotropic medium is obtained. The task of ultrasonic plane light wave diffraction in the wide-band anisotropic diffraction geometry near the optical axis in the Te0[2] crystal is considered.

## An application of computer simulation to detector calibration in the aqueous medium

Published in category «Nuclear physics»

Authors offer the calculation method to calibrate detectors in radioactive aqueous medium using a computer program — «МСС 3D». First of all radius of sphere with radioactive substance has been calculated. This volume is similar to infinite matter with this substance. Then the calculation time reduction method was presented. As a result the detector response function was obtained and compared with experimental data.

## K[s]-meson suppression in central Au+Au collisions at center-of-mass energy of 200 GeV per nucleon pair

Published in category «Nuclear physics»

Measurements for K[s]-meson production at high transverse momentum in Au+Au collisions at center-of-mass energy of 200 GeV per nucleon pair are presented. A fourfold-fivefold suppression of the K[s]-meson yield in central Au+Au collisions is found.

## K[s]-meson production in Cu+Cu collisions at center-of-mass energy of 200 GeV per nucleon pair

Published in category «Nuclear physics»

Measurements for K[s]-meson invariant yields and nuclear modification factors at high transverse momentum in Cu+Cu collisions at center-of-mass energy of 200 GeV per nucleon pair are presented. A twofold-suppression of the K[s]-meson yield in central Cu+Cu collisions is found to authenticate of the hot and dense matter creation in the central ultrarelativistic Cu+Cu collisions.

## On phenomenological gradient dependences

Published in category «Mechanics»

Different means of introduction of the finite disturbance propagation velocity while the gradient dependences including in heat- and mass transfer theory are presented. The model of diffusion with finite velocity makes it possible to reveal the mechanism of molecular susceptibility to the local concentration distribution. The finite velocity of heart transfer is provided including the relaxation time in Fourier law. In fluid mechanics Maxwell body as a reologic model of viscoelastic medium leads to hyperbolic hydrodynamic equations, containing disturbance propagation velocity equal to sound velocity.

## Evaluation of thrust effectiveness for nozzles of rocket microthrusters

Published in category «Mechanics»

An influence of shear stress upon a thrust of conical nozzle with throat diameter of 10[-5]-10[-6] m has been under the study. Including of its input into determination of thrust was done with the use of the model of laminar boundary layer. It allowed to establish an existence of optimal nozzle length. This length was shown to depend essentially on throat diameter. An influence of properties of issuing gas and nozzle half-angle upon the thrust was studied. Developed method of estimation of nozzle thrust effectiveness can be used on preliminary step of design.

## Specific mechanical momentum of shock wave as a physical parameter of loading

Published in category «Mechanics»

The closeness of the parameters of shock waves at various ways of loading allows someone to use the specific mechanical momentum as a loading parameter. The application of this parameter in engineering applications is considered.

## An implementation of the functional approach to a posteriori error control of solutions in 3D elasticity

Published in category «Mechanics»

As an example of problems in 3D linear elasticity solved by ANSYS, the efficiency of the functional approach to a posteriori error control is investigated. The approach is implemented as an external FORTRAN-based computational module. The numerical investigations show that the approach is promising and provide the way to draw around the area for its reliable use.

## An antiplane crack partially penetrating an elastic circular inclusion with coating

Published in category «Mechanics»

An interaction of the semi-infinite crack of mode III with circular uncoated/coated inclusion is examined. As a result the use of the generalized integral transform of Mellin in the problem for the uncoated inclusion an exact analytical solution in the locked form is obtained. With the presence of coating the problem is brought to the solution of two integral Fredholm equations of second kind relative to displacements on the interfaces. The dependence of the stress intensity factor from the elastic modules of composition is studied.

## Spectral diagnostics of the interstellar radiative shocks

Published in category «Astrophysics»

A model of a radiative shock propagating through interstellar medium has been developed to study continuum and line emission produced in downstreams of such shocks. Being confronted with available observations of galactic supernova remnants, the computed spectra can help to reveal information about physical conditions in these objects.