Local field of spin-spin interactions in the nuclear spin system of n-GaAs

At low lattice temperatures the nuclear spins in a solid form a closed thermodynamic system that is well isolated from the lattice. Thermodynamic properties of the nuclear spin system are characterized by the local field of spin-spin interactions, which determines its heat capacity and the minimal achievable nuclear spin temperature in demagnetization experiments. We report the results of measurement of the local field for the nuclear spin system in GaAs, which is a model material for semiconductor spintronics. The choice of the structure, a weakly doped GaAs epitaxial layer with weak residual deformations, and of the measurement method, the adiabatic demagnetization of optically cooled nuclear spins, allowed us to refine the value of nuclear spin-spin local field, which turned out to be two times less than one previously obtained. Our experimental results are confirmed by calculations, which take into account dipole-dipole and indirect (pseudodipolar and exchange) nuclear spin interactions.Comment: 23 pages, 6 figures, 1 tabl

Simultaneous measurements of nuclear spin heat capacity, temperature and relaxation in GaAs microstructures

Heat capacity of the nuclear spin system (NSS) in GaAs-based microstructures has been shown to be much greater than expected from dipolar coupling between nuclei, thus limiting the efficiency of NSS cooling by adiabatic demagnetization. It was suggested that quadrupole interaction induced by some small residual strain could provide this additional reservoir for the heat storage. We check and validate this hypothesis by combining nuclear spin relaxation measurements with adiabatic remagnetization and nuclear magnetic resonance experiments, using electron spin noise spectroscopy as a unique tool for detection of nuclear magnetization. Our results confirm and quantify the role of the quadrupole splitting in the heat storage within NSS and provide additional insight into fundamental, but still actively debated relation between a mechanical strain and the resulting electric field gradients in GaAs.Comment: 11 pages, 4 figures, 1 tabl

АНАЛИЗ РАБОТЫ ГАЗООЧИСТНОЙ УСТАНОВКИ ОБЖИГОВОГО УЧАСТКА ПОЛУЧЕНИЯ ТЕХНИЧЕСКОГО СЕЛЕНА

There was considered process of recovery of selenium dioxide in calcination-selenide technology of selenium obtaining in metallurgical shop of copper plant of Polar division MMC «Norilsk Nickel». There was established that discharge of selenium in the air occurred as fine dispersed condensation aerosols SeO2, which did not recovery by the apparatus of «dry» and «wet» gas cleaning. The content in aerosols of crystalline phases of sodium selenite, copper and nickel is negligible. During researches there were proposed measures on improvement of hollow scrubber operation and substitution of jet-foaming apparatus for foam scrubber. Outfit of scheme of scrubbing by spray-type absorber-condenser, in which will be realized steam condensing enlargement of aerosols of SeO2, will allow more effectively recover aerosols and transform engineering scrubbing into sanitary one.Рассмотрен процесс улавливания диоксида селена в обжигово-селенидной технологии получения селена в металлургическом цехе медного завода ЗФ ОАО «ГМК «Норильский Никель». Установлено, что вынос селена в атмосферу происходит в виде тонкодисперсных конденсационных аэрозолей SeO2, которые не улавливаются аппаратами «сухой» и «мокрой» газоочистки. Содержание в аэрозолях кристаллических фаз селенатов натрия, меди и никеля невелико. В ходе исследований предложены мероприятия по улучшению работы полого скруббера и замене струйно-пенного на барботажно-пенный аппарат. Оснащение схемы газоочистки орошаемым абсорбером-конденсатором, в котором реализуется пароконденсационное укрупнение аэрозолей SeO2, позволит более эффективно их улавливать и трансформировать технологическую газоочистку в санитарную

MORPHOLOGY OF THE SURFACE OF COOKED SAUSAGES MADE WITH THE COLLAGEN-CONTAINING PROTEIN ADDITIVE “BILKOZYNE”

The purpose of this study was to investigate the effect of the collagen-based additive Bilkozyne on the texture of cooked sausages. This additive is a food ingredient obtained by partial hydrolysis of a beef skin split. We suggested that Bilkozyne usage in the formulae of meat products will allow reducing production costs and improving the texture of the final product. We used scanning electron microscopy (SEM) regarded as a unique tool in the comprehensive research of the texture of food products. Prior to that, we had developed a protein stabiliser (PS), based on Bilkozyne and other hydrocolloids, in order to distribute fats uniformly in the protein matrix of mincemeat. The influence of PS on the surface morphology of dried samples of cooked chicken sausages made from the mincemeat has been investigated. The main component (60 %) of the PS was collagen containing the protein Bilkozyne. The PS levels in the cooked sausages were 10 % and 15 %. Qualitative changes of the texture of cooked sausages have been examined by means of high resolution SEM. The following morphological parameters of the samples have been examined: the number of holes per 1000 µm2 of the area of the sample; the average area of the holes, µм2; the holes ellipticity; the average area of the surface without the holes per 1000 µм2 of the area of the sample. It has been shown that adding 10 % of the PS in the hydrated form results in essential improvement of the morphological features of the sausages as compared to those made with non-hydrated PS. It has been found that an increase of the PS in the formulae from 10 % to 15 % has a negative impact on the texture of the final products, causing a significant decrease in the hydration degree of the myofibrillar proteins of the meat’s muscle tissues. Bilkozyne has a positive effect on the distribution of fats and proteins in the mincemeat. This makes it possible not to change the source of fats in cooked sausages. Thus, the inclusion of Bilkozyne into the formula of cooked sausages results not only in the improvement of their texture, but also in the increase of essential amino acids content.</p