Search

The article discusses the features of the radiation of ultrafast point clusters of charged particles moving uniformly near a gyrotropic medium interface. It is shown that some types of electromagnetic radiation – transient and/or Cherenkov radiation – have the characteristics of superchiral fields. Therefore, they can be effectively used to study chiral structures (for example, to detect circular dichroism, the frequency characteristics of refractive indices), various materials, including biomaterials. Ultrafast (relativistic) particles can serve as a «tool» not only for studying the structure of various materials. They can also be used as «generators» of quasiparticles that determine the «dynamic» properties of the materials under study, as well as the features of their interaction with radiation of various nature and response to external influences. In this paper, some types of circularly polarized EM waves propagating in optically active (magnetoactive, naturally active, gyrotropic, and chiral) media are considered. Using the generalized reciprocity theorem for media characterized by the Hermitian permittivity tensor, we consider the transient and Cherenkov radiation excited by a uniformly moving bunch of charged particles when it crosses (or moves along) the interface of media, one of which is an optically active gyrotropic medium. It is shown that the superchiral electromagnetic fields of the transition and Cherenkov radiation of dipoles can serve as a source of chiral collective excitations in magnetoactive and naturally active media. The investigated mechanisms of interaction of electromagnetic radiation with chiral materials (structures and media) are one of the possible physical approaches to solving the problem of the chiral purity of the biosphere and to elucidate the factor of deracemization of the organic primeval environment. A new hypothesis is presented, suggesting that ultra-high-speed clumps of charged particles of cosmic origin can cause deracemization of the prebiosphere.

The paper presents the results of studies of the spectral properties of a photosensitizer based on indotricarbocyanine dye when accumulating in tissues of experimental animals. Using laser fluorescence spectroscopy, the in vivo and ex vivo fluorescence spectra of tissue-localized indotricarbocyanine dye were obtained for different time counts after intravenous administration. The profile of the pharmacokinetics of its accumulation and withdrawal was determined from the change in the intensity of fluorescence in the tumor and healthy muscle tissues of the photosensitizer. A monotonic deformation of its fluorescence spectrum was revealed in the tissues of tumor nodes and muscles of the thigh when registered through the skin over time after intravenous administration. The achievement of the maximum accumulation of the photosensitizer in the tumor correlates with the stabilization of the shape of its in vivo fluorescence spectrum. Thus, the maximum shift can be used as a diagnostic indicator of the maximum accumulation of indotricarbocyanine photosensitizer in the tumor tissues. The results were confirmed for two groups of animals: the first one – black mice of the C57Bl/6 line with an inoculated tumor of Clone M3 melanoma, the second – white mice of the ICR line with an inoculated tumor of Ehrlich ascites carcinoma. The analysis of the shape of the fluorescence spectrum of the photosensitizer during registration through the skin for animals with different colors has been carried out.

In this paper, we studied the effect of heat treatment on the texture characteristics of Co-Mo/Al2O3, a catalyst for the synthesis of carbon nanotubes (CNTs). It has been experimentally proved that the heat treatment conditions at the stage of obtaining the metal oxide catalyst have a significant effect not only on its morphology, but also on its activity in the process of synthesis of CNTs. It was found that the implementation of the heat treatment of the starting components in one stage (decomposition) allows to obtain a catalytic system with a specific surface of ~ 14 ? 26 m2/g and a specific yield of ? ~ 5.2 ? 9.4 gС/gcat, and in two stages (decomposition / calcination) - Scat ~ 30 ? 147 m2/g and ? ~ 18.6 ? 30.0 gС/gcat. The smallest degree of defectiveness (ID / G ~ 0.53 ? 0.72) includes CNTs synthesized on a catalyst formed as a result of thermal changes for 10 min at 350 ° C and calcination at 500 °C, the diameter of the nanotubes is 15 ? 19 nm. The use of a metal oxide catalyst during the synthesis of CNTs, which has been calcined at higher temperatures (700 °C and above), leads to an increase in the speed and degree of defectiveness of the resulting nanostructures. Thus, the introduction of an additional heat treatment stage — calcination in the process of obtaining the Co-Mo/ Al2O3 catalyst — makes it possible to flexibly control the quality parameters of not only the formed metal oxide systems, but also the CNTs synthesized on them.

The purpose of the study is to monitor the efficiency of wheat resistance genes to the causative agent of brown rust (Lr-genes) in the Rostov region. Brown rust is the most widely spread and harmful wheat disease which annually occurs on the crops from poor development to epiphytoties. Soft wheat varieties grown in the region are variously resistant to this pathogen. To breed the brown rust resistant varieties, it is necessary to expand genetic basis of the varieties grown in the region and to attract new Lr-gene donors. Due to it the study of the monitoring of pathogen populations and the effectiveness of the known Lr-genes to the Rostov pathogen population is of great importance nowadays. For this purpose, the isogenic lines of the variety “Thatcher” with Lr-genes are annually studied in the Agricultural Research Center “Donskoy” on the infectious plots and in the laboratory conditions in the sprouting phase. This paper presents the monitoring results of the populations in the period of 2015–2017. The variety “Tarasovskaya 29” served as a universally susceptible variety. In this work, there were used generally accepted methods of working with brown rust pathogen in the “sprouting” and “grown-up” periods. It has been established that in the “grown-up” period, 10 lines showed a high resistance to the disease (0% of damage), 6 lines did not exceed 10%, and 11 lines had moderate susceptibility (30–40% of damage) to the pathogen. The remaining lines were susceptible to the pathogen population. The virulence analysis of the plants in the sprouting phase showed high efficiency of the Lr9, Lr19, Lr24, Lr28, Lr29, Lr41, Lr42, Lr45, Lr47, Lr50, Lr51, and Lr53 genes. The phenotypic (racial) composition of the Rostov fungus population was identified using 20 TcLr-lines. In 2016–2017 in the Rostov population there were identified 6 phenotypes. RNTH, RNTKG and TNTTH were common phenotypes in both years of research. The identified effective Lr-genes can be used to develop resistant wheat varieties, taking into account the plants’ ontogenesis.

Trivalent gallium compounds are structural analogs of the elements with variable valency in (+3) oxidation state that can be used as cathode materials for electrochemical power devices (iron, vanadium, chromium). Literature data about gallium(III) sulfate are quite scarce. So, we developed a preparation technique for synthesizing Ga2(SO4)3 from Ga(CH3COO)2OH as a starting material. The latter was dissolved in sulfuric acid. Then gallium(III) sulfate hydrate was precipitated under cooling. The obtained precipitate is extremely hygroscopic, and it deliquesces quickly under aerobic ambient conditions. The synthesized gallium(III) sulfate hydrate was dried on the filter and then kept in vacuum at 10-2 torr for two hours to remove traces of water and acetic acid. Gallium(III) sulfate, its intermediates and products of its thermal treatment were studied by differential thermal analysis (DTA) and X-ray diffraction phase analysis. The content of crystallization water in gallium(III) sulfate hydrate was determined, and the composition of the crystallohydrate was established as Ga2(SO4)3·18H2O. (The original X-ray diffraction pattern of the latter is disclosed below in this paper.) The mentioned crystallohydrate lost its water in six steps within 40-350 °С temperature range and formed anhydrous Ga2(SO4)3, which, in turn, decomposed at 700 °С and produced nanocrystalline gallium oxide, Ga2O3. Anhydrous gallium(III) sulfate is slightly hygroscopic, so it should be stored in a desiccator. It was found that propanol-2 (isopropanol) can be used to precipitate gallium(III) sulfate from aqueous sulfuric acid: isopropanol extracts acetic acid and, thus, exhibits salting-out activity. The formed amorphous precipitate partially loses its mass when heated up to 400 °С. However, a single phase Ga2(SO4)3 specimen could not be synthesized by this method. Considering similarities between gallium and indium, it can be assumed that Ga2(SO4)3 precipitate is contaminated by gallium oxosulfate.

The low level of complexity in the processing of raw materials at mining and processing enterprises adversely affect the environment causing considerable damage to it. Meanwhile technological waste is a cheap source of raw materials for liquid products of functional purpose, particularly inorganic filler which are widely used in the manufacture of paints and building materials, paper, plastics, insulating and protective materials. Improved performance and physical and chemical properties of materials are achieved by optimizing the composition and dispersion of the particles. By the example of the research subjects received from the flotation waste nepheline ore-dressing, it has been shown that a high degree of homogenization to obtain fine mixtures (75 % of 3–4 micron fraction) composite filler powders the ultrafine grinding method achieved by using a planetary ball mill for a short period of time (at least 1 hours). The use of other grinding methods, for example by means of ball mill or a vibration such effect is not obtained. At the conditions of ultrafine grinding the ionization and amorphization of the surface layer of powder material particles (mechanical activated processing) are occurred. This increases its activity by reacting with organic and inorganic binding, and provides high performance. The obtained filler has been tested in the composition of temperature-controlled sealants and glues used in the aerospace industry, shipbuilding and electronics. To obtain such materials sphene and nepheline received from industrial tailings of Khibiny apatite-nepheline ore deposits are used

This paper investigates the mechanisms of proton-relaxation polarization and thermally stimulated currents of depolarization (TCDP) in hydrogen bonded crystals (HBC) using methods of quasi-classical kinetic theory. Established generalized expressions for the complex dielectric permittivity (CDP) and polarization incorporates the main frequency of varying polarization field in the infinite approximation of perturbation theory with respect to a small parameter. It is revealed that that the effects of interaction among the relaxation modes of volume charge density starting from the main frequency of the field have already caused abnormally high polarizing nonlinearities in the range of strong fields (10-1000 MV/m) and ultra-high temperatures (550-1500 K). Generalized along the field expressions are established for kinetic equation coefficients. These expressions allow revealing reveal the influence of the field parameters (amplitude and frequency of the EMF) on the microscopic acts of transfer of physical relaxation oscillators (protons) through the potential barrier. The expression for the density of thermally stimulated currents of depolarization in HBC carried out in the wide range of fields (100-1000 MV/m) and temperatures (1-1500 K) is formulated on the basis of the general kinetic equation solution (for the model of a double symmetric potential well with a parabolic barrier). A numerical computation scheme for characteristic parameters oscillators is developed using the minimization comparison function method (MCF-method)., Методами квазиклассической кинетической теории исследуется механизм протонно-релаксационной поляризации и термостимулированной деполяризации в кристаллах с водородными связями (КВС). Построены обобщенные выражения для комплексной диэлектрической проницаемости (КДП) и поляризации, выполняющиеся на основной частоте переменного поляризующего поля в бесконечном приближении теории возмущений по малому параметру. Установлено, что эффекты взаимодействия релаксационных мод объемной плотности заряда уже на основной частоте поля обусловливают аномально высокие поляризационные нелинейности, проявляющиеся в области сильных полей (10-1000 МВ/м) и сверхвысоких температур (550-1500 К). Построены обобщенные нелинейные по полю выражения для коэффициентов кинетического уравнения, позволяющие выявить влияние параметров поля (амплитуда и частота ЭДС) на микроскопические акты перебросов физических релаксаторов (протонов) через потенциальный барьер. Из решения общего квазиклассического кинетического уравнения (для модели двойной симметричной потенциальной ямы с барьером параболической формы) построено выражение для плотности тока термостимулированной деполяризации в КВС, выполняющееся в широком диапазоне полей (100-1000 МВ/м) и температур (1-1500 К). Предложена схема численного расчета характеристических параметров релаксаторов методом минимизации функции сравнения (МФС-методом).

Diffraction of waves of different physical nature is one of the most important and studied phenomena of nature in connection with its versatile use in devices and measuring techniques. The influence of media motion on the diffraction pattern attracted the attention of researchers in connection with the development of the theory of the electrodynamics of moving media and continues to attract attention in connection with a number of unsolved problems of physics. In this paper, we consider a model of the diffraction of waves on the slit and lattice, located on amovable substrate (medium). Analytical relations for the calculation of the diffraction pattern intensity distribution are obtained. The significant influence of the medium motion on thediffraction pattern is established. The position of the zero-order maximum does not depend on the motion of the medium, on the one hand, the distance between the diffraction maxima decreases, on the other hand, increases, until they disappear. The conditions under which the motion of themedium leads to an asymmetrical appearance of the diffraction intensity distribution, which is not observed in a stationary medium, are established. Generalized conditions of diffraction minima are obtained taking into account the motion of the medium. Shows the effect of the direction of thevelocity of motion of the medium on the intensity of the diffraction pattern.

High-purity hydrogen is required for clean energy and a variety of chemical technology processes. A considerable part of hydrogen is to be obtained by methane conversion. Different alloys, which may be wellsuited for use in gas-separation plants, were investigated by measuring specific hydrogen permeability. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones), and identify the limiting factors. This paper presents a nonlinear model of hydrogen permeability in accordance with the specifics of the experiment, the numerical method for solving the boundary-value problem, and the results of parametric identification for the alloy V85Ni15.

Введение. Статья предоставляет обзор научных открытий, касающихся магнитотак-тических бактерий (МТБ). Результаты открытий используются в микробиологии, минералогии, лимнологии, физике, биофизике, химии, биохимии, геологии, кристаллографии и астробиологии. Магнитосомы МТБ организованы в линейные цепи и ориентируют клеточные тела вдоль силовых линий геомагнитного поля, причем вращательные движения жгутиков приводят к т. н. магнитотаксису. Материалы и методы. Обзорная статья о бактериях, чувствительных к магнитному полю, является компиляцией нескольких научных работ из различных научных учреждений. Наиболее важные моменты этого обзора сводятся к следующим положениям: 1) любая биологическая система способна создавать магнитные биоматериалы, такие как магнетит (Fe3O4) и грегит (Fe3S4); 2) навигация этих нанокристал-лов в биологической системе взаимосвязана с магнитным полем Земли. Результаты исследования. Исследователи, участвующие в изучении данной темы, показали, что магнитотактические бактерии действительно реагируют на магнитное поле. Это делает их привлекательными для медико-биологического и промышленного использования из-за наличия сильных электромагнитов, сверхпроводящих магнитов и постоянного магнита. Магнетические бактерии также могут быть использованы в качестве диагностического инструмента при обнаружении дефектов даже на наноуровне. Обсуждение и заключения. Несмотря на важность этой темы, которая пока находит лишь ограниченное применение в медицинской области, необходимо исследовать мир этих бактерий, которые являются кандидатами для использования в новых промышленных технологиях и терапевтических стратегий в медицины.Introduction. This outline explores the scientific discovery concerning the magnetotac-tic bacteria (MTB). The results of the discovery are used in microbiology, mineralogy, limnology, physics, biophysics, chemistry, biochemistry, geology, crystallography, and astrobiology. Magnetosomes of the MTB are organized in linear chains and orient the cell body along geomagnetic field lines while flagella actively propel the cells, resulting in so-called magnetotaxis. Materials and Methods. The review article about the magnetotactic bacteria is a collection of many research papers from different institutes. The emerging important points about this review lie in: (1) any biological system is capable of producing magnetic biomaterials such as magnetite (Fe3O4) and gregite (Fe3S4); (2) the navigation of these nano-crystals in the biological system is interconnected with the Earth's magnetic field. Results. The researchers involved in the study have shown that the magnetotactic bacteria do respond to a magnetic field. This makes them attractive for biomedical and industrial applications because of the availability of superior electromagnets, superconducting magnets and permanent magnet. Magnetic bacteria can also be used as a diagnostic tool in the detection of imperfections even at the nanoscale. Discussion and Conclusions. Although the importance of this issue is still limitedly used in medical area, more performance is necessary to explore the world of these bacteria that are candidate for new industry and new therapy strategies in biotechnology and medical fields.

The present paper deals with investigation of the possibility for application of laser welding-on technology for repairing the mold cavities of die casting dies. The surface of the samples, made of 32CrMoV12-28 (DIN) steel, was welded on by additional material – maraging alloy with chemical composition 0.02С–19.3Ni – 0.4V–2Cr-14.5Co–4.7Mo–0.25Al–0.2Mn–0.2Si, (wt %). The surface treatment was done by pulse laser AL 200 Nd:YAG with a wave length of 1064 nm. To estimate the possibility for additional hardening of the welded-on layers, the samples were heated for 1 hour at temperatures of 450, 500, 550 and 600 °С. The microstructure was investigated by light microscopy, the Vickers microhardness was measured with 100 g load and XRD-analysis was done. After laser welding-on the hardened surface layer was obtained. Its microstructure possesses dendrite morphology and consists mainly of ferrite oversaturated with alloying elements. The intermetallic compounds of the types Fe-Cr and Fe-Al are also observed. After ageing Ni-Al and Ni-Mo phases precipitate with maximal quantity at a temperature of 550 °C. After ageing at this temperature a maximal hardness of 600–650 HV, twice higher than that of the welded-on layer, was observed. The next temperature increase leads to the hardness decrease up to 400–450 HV due to the interruption of the coherent bonds between the phases and transformation of dendrite morphology to equiaxed crystals. As a result of the present investigation the application of the laser welding-on with additional material – maraging alloy, could be recommended for repairing the mold cavities of die casting dies.