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Shaganov Anton P., Vakhrushev Sergey B., Filimonov Alexey V., Ohwada Kenji

Coherent X-ray scattering as technique of nanoregions formation study in model PMNPT10 relaxor

Published in category «Condensed matter physics»

The paper describes a method for nanoinhomogeneous materials diagnostics using coherent X-ray (synchrotron) radiation through the example of a model ferroelectric relaxor lead magnesium niobate-lead titanate (PMNPT10). The results of X-ray scattering experiments on PMNPT10 show the presence of foci of polarization in the material both below and above the phase transition temperature. The results of modeling of scattering by simple two-dimensional lattices also are presented.

Views: 1694 Comments: 0

Komarova Olga S., Martynova Olga A., Gasumyants Vitaly E.

Cerium doping influence on the energy spectrum parameters in the Nd[2–x]Ce[x]CuO[y] system

Published in category «Condensed matter physics»

The temperature and concentration dependences of the thermopower in Nd[2–x]Ce[x]CuO[y] (х = 0.025 – 0.250) system have been analyzed using three models of the electron transport, i.e. Xin's two-band model, two band model with a linear T-term and narrow-band model. It is shown, that the best agreement of the experimental and calculated results can be achieved in the framework of the narrow-band model. The model parameters in studied samples were determined and a character of their variation with increasing cerium content was analyzed. This allows us to confirm the validity of the supposition that a new narrow conduction band is formed in the Nd[2]CuO[y] energy spectrum under cerium doping.

Views: 1331 Comments: 0

Veis Alexander N., Zhitinskaya Maria K., Lukyanova Lidia N., Kutasov Vsevolod A.

Peculiarities of bismuth telluride energy spectrum from optical measurements data

Published in category «Condensed matter physics»

Spectral dependencies of optical reflection and absorption coefficients in n- and p-Bi[2]Te[3] at T = 300 K have been investigated and analyzed. The band scheme of bismuth telluride corresponded to experimental data was put forward.

Views: 1242 Comments: 0

Borisov Vladimir L., Borisova Margarita E.

The determination of the carrier mobility in transparent ferroelectric ceramics

Published in category «Condensed matter physics»

The surface potential decay in transparent ferroelectric ceramics PLZT-9 determined by charge relaxation processes in ceramics has been studied. The experimental results were analyzed on the basis of dispersive transport model that proposed repeated trapping of charge carriers into deep traps with their consequent thermal releasing and moving through ceramics bulk. The time-dependence of carrier mobility at constant temperature was calculated.

Views: 991 Comments: 0

Tsakaev Abdul-Vakhab V., Kochereshko Vladimir P.

Effects of exciton spatial dispersion in zinc selenide quantum wells

Published in category «Condensed matter physics»

The phenomenon of the natural optical activity has been found and studied in ZnSe/ZnSSeMg single quantum well using reflectivity spectra at oblique light incidence.

Views: 925 Comments: 0

Pashchenko Vladimir P.

Controlled surface acoustic wave phononic crystal based on induced periodic domains

Published in category «Condensed matter physics»

A novel type of controllable phononic crystal controlled by external static electric field that induced periodic domains in ferroelectric thin film has been proposed. Finite element simulation results of frequency dependent of transmission coefficient and dispersion curves at first Brillouin zone are presented. The change of phononic band gap width via changing the electric field which induced the periodic domains in ferroelectric thin film was shown.

Views: 806 Comments: 0

Kozyrev Dmitry S., Burbaev Timur M.

Electron-hole liquid yellow-green photoluminescence in SiGe tunnel-transparent layers of silicon heterostructures

Published in category «Condensed matter physics»

The formation of quasi-two-dimensional multiparticle excitations − biexcitons, electron-hole liquid (EHL) and plasma in tunnel-transparent for electrons SiGe layers of Si/Si0.91Ge0.09/Si heterostructures has been investigated by methods of photoluminescence (PL) in the near-infrared (NIR) and visible spectral ranges. When the PL line form in the visible region was compared with the numerical convolution of the spectrum in the NIR region, corresponding to one-electron transitions in EHL, it was apparent that the radiation in the visible region at low temperatures and high levels of excitation were caused by the two-electron transitions in quasi-two-dimensional EHL.

Views: 825 Comments: 0

Abramov Alexei G., Kovalev Gordei A., Smirnov Evgeny M.

Numerical simulation of circulation of steam-air mixture and film condensation on series of vertical tubes

Published in category «Simulation of physical processes»

The paper presents results of 3D steady-state RANS computations of turbulent convection of steam-air mixture performing a circulating motion in a confined enclosure under conditions of film condensation of steam on an infinite row of cooled vertical tubes located in the central part of enclosures. The aim of the computations is to study the influence of the distance between the tubes on the flow structure and heat transfer characteristics. Software implementation of the presented mathematical model of the processes under consideration has extended the possibilities of the in-house CFD-code SINF. On the base of the obtained computational results a comprehensive analysis of the structure of the velocity, temperature and concentration fields, as well as the distribution of the heat flux on the surfaces of the tubes is done.

Views: 1368 Comments: 0

Verkhovtsev Alexei V., Korol Andrei V., Solov'yov Andrei V.

Theoretical investigation of electron excitations in photoionization of nanoscale carbon-based systems

Published in category «Atom physics and physics of clusters and nanostructures»

We present the results of investigation of electron excitations in various carbon-based nanoscale systems in the process of photoionization. As a case in point, we consider a number of highly symmetric fullerenes, namely C[20], C[60] and C[80], as well as aromatic hydrocarbons: benzene (C[6]H[6]) and coronene (C[24]H[12]). The calculations are performed within the model approach, based on the plasmon resonance approximation, and the ab initio framework as well. Analysis of the results demonstrates that the main contribution to the photoionization spectra of nanoscale carbon systems is due to collective excitations of delocalized electrons, known as plasmons. Results of the model-based calculations are in close agreement with those of the more accurate quantum-chemical calculations and correspond also to the existing experimental data.

Views: 1510 Comments: 0

Skublov Alexei S., Sovkov Vladimir B., Ivanov Valery S.

Triplet states of heavy alkali metal dimers: observation and analysis

Published in category «Atom physics and physics of clusters and nanostructures»

The latest results on the study of the triplet states of the heavy alkali metal dimers have been summed up. The investigations were aimed at an analysis of the experimental data on the perturbation facilitated optical-optical double resonance (PFOODR) spectroscopy. The technique of such data treatment was described and demonstrated.

Views: 1294 Comments: 0

Serebryakov Alexander S., Moroz Andrei P., Berdnikov Yaroslav A., Miller Mikhail B., Efremov Yuri V., Khrunov Vladimir S.

The features of the silicon gamma-ray detector amplitude spectra

Published in category «Experimental technique and devices»

The paper considers the peculiarities in gamma-ray spectra collection by silicon detector. The computer model which takes into account inhomogeneous charge collection in the detector volume allows calculation of correct spectra for essentially different gamma-line energies which coincide with the experimental spectra rather well. The influence of incomplete charge collection in the crystal sensitive volume by amplitude spectra is demonstrated.

Views: 1477 Comments: 0

Berdnikov Yaroslav A., Berdnikov Alexander Ya., Yevseyev Valery A., Miftakhov Nail' M., Nikulin Vladimir N., Samsonov Vladimir M., Tarasenkova Olga P.

Muon arm upgrade and beampipe support in ALICE experiment at LHC

Published in category «Experimental technique and devices»

The paper describes the integration aspects of the ALICE Muon Arm upgrade, the beam-pipe support in particular. Two options were considered. The test bench built in order to estimate the uncertainties in the mechanical analysis caused by the bellow model was described. It was also demonstrated that simple model of the bellows gives reasonable description of the results.

Views: 1432 Comments: 0

Aronova Ekaterina S., Emelyanov Victor M., Shvarts Maxim Z.

Prediction of energy performance of multijunction A{3}B{5} photoconverters with optical concentrators in different geographic regions

Published in category «Experimental technique and devices»

In the paper the simulation of the response of the working parameters of multijunction A{3}B{5} photoconverters with optical concentrators on the change in the spectral composition of the solar radiation in different climatic conditions has been performed. Energy production of the photoconverters in several geographical locations was estimated. It was shown that inaccuracy of prediction of the energy production might be up to 16 % high in the case of neglecting photoconverter efficiency changing under the incident light spectral composition variation.

Views: 1214 Comments: 0

Mishin Maxim V., Alexandrov Sergey E.

Electrical potential distribution along the reactor with atmospheric pressure remote plasma

Published in category «Experimental technique and devices»

The original design of electrical probe and the investigation techniques for ion flux characteristics have been developed. The measurements were carried out in the reactor equipped remote low temperature plasma generated by radio-frequency (RF) helium discharge (13.56 MHz) at atmospheric pressure. The experimental data on distributions of ion concentrations and electrical potential along the reactor, outside of the discharge gap were given.

Views: 1316 Comments: 0

Babenko Tatiana N., Golyaeva Anastasia Yu., Lobanov Petr Yu., Manuylovich Ivan S., Sidoryuk Oleg E.

Quality evaluation for optical glass-ceramics parts using laser phase-shifting interferometry

Published in category «Experimental technique and devices»

The article is devoted to refinement of the criteria of striae control of optical glass-ceramics, introduction of quantitative characteristics through the use of phase-shifting interferometry techniques with the construction of local wavefront distortion maps in the material volume.

Views: 1084 Comments: 0

Demkin Vladimir N., Stepanov Vladimir A., Shadrin Maxim V.

Rapid prototyping systems with laser scanning

Published in category «Experimental technique and devices»

The article considers the influence of the factors limiting the accuracy of the laser triangulation measuring instruments and especially their applications in rapid prototyping. Particular attention is paid to an abrupt change of the reflection coefficient, the influence of slope and shadow areas. To improve scanning accuracy and reduce the factors that limit the possibilities of triangulation gauges, we propose a new orthogonal to the optical design of the laser sensor.

Views: 1115 Comments: 0

Emelyanov Alexei Yu., Gabdullin Pavel G., Arkhipov Alexander V., Gnuchev Nikolay M.

Surface morphology and field emission of the magnetron deposited carbon films

Published in category «Physical electronics»

The influence of growth temperature of carbon films on their surface morphology and field emission has been investigated. Growth temperature range, where carbon-on-silicon films display the emission activity was found.

Views: 1580 Comments: 0

Kiesewetter Dmitry V., Ilin Nikita V.

The intensity distributions of the light near the output end of the optical fiber in the presence of optical vortices

Published in category «Physical optics»

The effect of rotation of speckle of multimode optical fiber has been confirmed experimentally when moving plane observations along the fiber axis near the surface of the output end. Using the calculation of cross correlation function between the distributions of intensity the angular speed of rotation of speckle was determined.

Views: 1171 Comments: 0

Kniazkov Anatoly V.

Polarize-optical light modulation

Published in category «Physical optics»

An analysis of polarize-optical modulation (POM) of the light flow by electro-optical (EO) medium has been performed. POM without aperiodic transformation and with the transformation of the spectrum was reviewed. It was shown that the electro-optical modulation occured with the transformation of the spectrum. The dependence of the contrast ratio POM of the width of the emission spectrum in the case of one EO medium and the optical transmission of the modulated radiation POM for the two EO mediums were obtained.

Views: 1137 Comments: 0

Arbuzov Vitaly A., Bufetov N.S., Aliukaeva Olga Z.

The determination of density and concentration of aqueous solutions of salts by optical way (lithium bromide as an example)

Published in category «Physical optics»

The results of investigation into a technique for determination of density and concentration of aqueous solutions of salts through a lithium bromide solution as an example have been presented, using changes of a refractive index that depend on solution density. Refractive index values for LiBr solution depending on concentration and temperature for monochromatic radiation at wavelengths of 660 and 532 nm were obtained.

Views: 1584 Comments: 0

Morozova Natalia E., Vedyaykin Alexey D., Sabantsev Anton V., Pobegalov Georgiy E., Murashov Sergey V., Khodorkovskii Mikhail A.

Membrane tether formation from human hepatocytes

Published in category «Biophysics and medical physics»

For the first time to our knowledge the mechanical properties (membrane tension and apparent viscosity) of human hepatocyte (HepG2 cell line) membranes were measured by membrane tether formation using optical trap. Membrane tension and apparent membrane viscosity were measured to be 40 ± 3 pN and 0.27±0.07 pN·s/µm respectively. The developed procedure can be used to study connections between liver cell membrane mechanics and different factors, including ethanol and drug consumption, aging, pathological processes, etc.

Views: 1602 Comments: 0

Skvortsov Nikita V., Samoilov Vladimir O., Larionov Ivan V., Boldyrev Alexander G.

An effective sorbent for elimination endotoxin in biological products of genetically engineered genesis and biological liquids

Published in category «Biophysics and medical physics»

An effective sorbent designed to eliminate endotoxin from biological fluids and products has been developed. A highly permeable biocompatible matrix based on regenerated cellulose was used as a base of the sorbent. The efficiency of the sorbent for endotoxin from model solutions and protein solutions were estimated.

Views: 1396 Comments: 0

Nikonorova Natalia A., Kapralova Victoria M., Castro Arata Rene Alejandro, Zhuravlev Dmitry A.

Dielectric relaxation of grafted polyimides with long polytretbuthylmethacrylate side chains

Published in category «Physics of molecules»

Molecular mobility of polyimide brushes, grafed polymers with long polytretbuthylmethacrylate side chains, was investigated by dielectric method. In the glassy state two local relaxation processes, β and β1, whose molecular mobility depends weakly on side chain lengths, were found. In the viscous elastic state the α cooperative relaxation process caused by segmental motion of side chains was observed. For the α process, the molecular mobility decreases with the length of polytretbuthylmethacrylate side chains.

Views: 1361 Comments: 0

Alekseenko Sergei N., Shemyakina Tatiana A., Dontsowa Marina V.

Nonlocal resolvability conditions for systems of the first order partial differential equations

Published in category «Mathematics»

Conditions of a nonlocal resolvability of the Cauchy problem for a system of two quasilinear first order partial differential equations are received. The investigation of the considered problem is based on the method of an additional argument.

Views: 2489 Comments: 0

Gorev Boris V., Panamarev Victor A.

The integrated characteristics method for calculation of a bend of design

Published in category «Mechanics»

Possibility of use of integrated characteristics on a bend [1] for calculation of forming process and relaxations of details with a constant thickness from sheet and plates having surfaces close to developable from anisotropic alloys with different resistance to a stretching and compression at a flat stress state in the creep conditions is proved. The technique of definition of functional dependences parameters from processing of experimental diagrams on a pure bend of rectangular beams and torsion of square plates for calculation process of plates bending with use of the relationship between rates of change curvature and the moments for orthotropic materials in the assumption of identical properties on a stretching and compression is spent [2].

Views: 1254 Comments: 0

Larichkin Alexei Yu., Gorev Boris V.

The constructing shear strains from the pure torsion of round solid samples

Published in category «Mechanics»

Through the example of titanium VT-9 and aluminium alloys (D16T, AK4-1T, AMG-6M) the possibility of describing the creep and fracture on torsion of solid round samples has been demonstrated. The power law of creep was used. The kinetic creep equation in the energy form describes three stages of creep. Satisfactory agreement between the experimental and settlement data was obtained.

Views: 1207 Comments: 0

Ganin Pavel G., Schmidt Alexander A.

Estimation of diameter of the smallest secondary droplets taking into consideration a number of break up tеsts of the largest droplets in the apparatus with stirring

Published in category «Mechanics»

This investigation is devoted to substantiation of the smallest droplets presence in polydisperse emulsion in a liquid – liquid system with stirring. A model of the smallest size secondary droplets formation is proposed: a break up of the largest droplets in a three secondary droplets, the model taking into consideration the number of tests per a break up during a time of droplets presence in the stirring zone. Calculated values are compared with known experimental data.

Views: 1384 Comments: 0

Sanin Andrey L., Semyonov E.A.

Quantum two-dimensional oscillators with Pallen – Edmonds coupling potential

Published in category «Theoretical physics»

The numerical integration of the non-stationary two-dimensional Schrodinger equation was carried out. In the context of quantum wave-packets, dynamical means, frequency spectra, uncertainty relations, autocorrelators there were studied the dynamical properties for two quantum oscillators coupled by the Pallen – Edmonds potential. In the regime of the weak coupling the many-frequency oscillations are generated, the spectral component number is increased at amplification of coupling.

Views: 1314 Comments: 0

Charikov Yuri E., Globina Veronika I., Sklyarova Elena M.

Hard X-ray time delay spectra of solar flares: BATSE spectrometer data

Published in category «Astrophysics»

A time delays of X-rays in the energy range of 20 – 200 keV registered by BATSE spectrometer during a space flight of CGRO have been considered. Pair wise correlation functions for all time series with a significant count rates were computed. Delay spectra are based via X-ray energy for different phases of flares. In the initial phase of the burst the delays increase monotonically with increasing energy. At the peak of the radiation pattern of the spectrum of different bursts is changing: from U-shaped to monotonically decreasing. On the decay phase of the count rate the delay spectra rather repeat the same of the maximum. A comparison of the delay spectra to the delays, following the models of the transport of the accelerated electrons were carried out.

Views: 1180 Comments: 0

Morachevski Andrey G., Firsova Elena G.

Academician Pavel Ivanovich Walden (On the occasion of his 150th birthday)

Published in category «Chronicle»

The article is devoted to a life and scientific activities of P.I. Walden (1863 – 1957), who was an outstanding chemist and a historian of chemistry. He took part in the foundation of Polytechnical Institute in Saint Petersburg, then was a rector of Riga Polytechnical Institute, an ordinary academician of Petersburg Academy of Science, a foreign honorary member of the Academy of Science of the USSR. The scientist is known, first of all, for his works on physical chemistry and electrochemistry of non-aqueous solutions as well on stereo-chemistry.

Views: 1428 Comments: 0