The electroluminescent characteristics of the InAs/InAs1-ySby/InAsSbP asymmetric light-emitting diode heterostructures with high InSb mole fraction in the active region (y>0.09) in the temperature range 4.2-300 K have been studied. Stimulated emission was achieved in the wavelength range 4.1-4.2 μm at low temperatures (T<30 K). It was found that the electroluminescence spectra were formed as a result of the superposition of contributions from different channels of radiative recombination of charge carriers near the type II heterointerface. The effect of the quality of the type II InAsSb/InAsSbP heterojunction on the radiative interface transitions with an increase in the content of InSb in the ternary solid solution is considered. Keywords: heterojunctions, InAs, antimonides, electroluminescence, light-emitting diodes.

The electrical and luminescent characteristics of the heterostructure with a 20 nm-wide n-InAsSbP/n-InAs0.95Sb0.05/p-InAsSbP single quantum well, grown on an n-InAs substrate by the MOVPE method, have been studied. An intense room temperature electroluminescence (EL) with a maximum near the photon energy of 0.34 eV and a FWHM of 32 meV was discovered. It was established that the EL in such single quantum well has been emitted due to type I radiative transitions between the ground levels of electrons and holes both at forward and reverse bias. The characteristics of heterostructures with a single quantum well and the active region based on a bulk InAsSb layer of the same composition have been compared.

The field dependence of the magnetization of a silicon nanosandwich observed at room temperature exhibits quite a complicated character, mainly due to the contribution of the quantum magnetic effect, which is interpreted as the de Haas–van Alphen effect at integer and fractional filling factors. Based on the earlier found two-dimensional carrier density of carriers, the critical fields for the corresponding filling factors have been calculated. Simulation of the de Haas–van Alphen oscillations has been performed at a high temperature ( T=300 K) based on the given energy density distribution of the silicon nanosandwich states in the neighborhood of the Landau levels by means of a calculation procedure realized at a supercomputer. The dependence of the effective mass of carriers on the strength of an external magnetic field that we revealed earlier has been taken into account.

Electroluminescent (EL) properties of asymmetrical InAs/InAs1-ySby/InAsSbP heterostructures with the y = 0.09 and y = 0.11 InSb content in the active layer were studied in wide temperature range T = 4.2-300 K. The stimulated emission in the spectral range 4.1-4.2 & mu;m has been observed at low temperatures (T < 30 K). It was estimated that EL spectra were formed owing to different channels of radiative recombination depending on the ambient temperature. The influence of the quality of the type II InAsSb/InAsSbP heterojunction on radiative recombination transitions has been considered.

Subject of study. In this study, methods for the topology formation of elements based on laser-induced periodic surface structures for implementing various visual effects and structural features in a security hologram recorded directly on the surface of AISI 430 stainless steel are investigated. Purpose of work. The process of recording images based on laser-induced periodic surface structures on bulk metals for creating dynamic images is optimized to solve problems in security holography. Method. The method is based on the formation of laser-induced periodic surface structures under the action of scanning laser radiation with simultaneous rotation of the polarization of laser radi-ation. The recording process is implemented using nanosecond fiber laser radiation with a wavelength of 1.064 mu m in a two-dimensional scanning system with a flat field objective. Main results. A technique is developed for creating a protective hologram comprising a set of laser prints filled with diffractive microgratings with different spatial orientations. The radiation polarization and beam scanning trajectory are the main factors influencing the laser-induced periodic surface structures' spatial orientation during the formation of structures with a given topology and observed visual dynamic effects based on elementary diffractive microgratings. The period of microdiffraction gratings is equal to the wavelength of the acting laser radiation and approximately 1 mu m. Practical significance. The proposed method for the elementary diffractive micrograting formation facilitates the generation of holographic elements/images with different spatial topologies, including various visual and structural features that meet the requirements for modern security holograms in their main application areas.(c) 2023 Optica Publishing Group

The electroluminescent characteristics of the InAs/InAs1−ySby /InAsSbP asymmetric light-emitting diode heterostructures with high InSb mole fraction in the active region (y > 0.09) in the temperature range 4.2−300 K have been studied. Stimulated emission was achieved in the wavelength range 4.1−4.2 μm at low temperatures (T < 30 K). It was found that the electroluminescence spectra were formed as a result of the superposition of contributions from different channels of radiative recombination of charge carriers near the type II heterointerface. The effect of the quality of the type II InAsSb/InAsSbP heterojunction on the radiative interface transitions with an increase in the content of InSb in the ternary solid solution is considered.

An obvious trend in domestic and foreign aquaculture in recent years is usage of biologically active substances of various mechanisms of action. It was clearly demonstrated that such biologically active substances as adaptogens, probiotics, vitamins, amino acids have a positive effect on the fish organism, increasing economic parameters of the industry. In particular, usage of "Irkutin" adaptogen in early ontogenesis of fish increased survivability of larvae during transition to exogenous nutrition, survivability of the fry, growth rate, endurance and it also reduced the level of cannibalism and stress. Therefore, the search for new substances with the properties of adaptogens for fish farming is of great importance. There is reason to believe that "cytrimin" can become such new substance. "Cytrimin" is a complex of tris-(2-hydroxyethyl) amine with zinc bis-(2-methylphenoxyacetate) and has the formula: (HOCH2CH2)3N Zn(OOCCH2OC6H4CH3-2)2. A study of the spectrum of physiological activity of "cytrimin" (one of the representatives of protatrans) showed that it protects blood vessels from formation of cholesterol plaques, it is also an antidote to alcohol and can increase performance, claiming to be an adaptogen. So far, "cytrimin" has not been used in fish farming. The aim of the work was to study the effect of "cytrimin" on parameters of blood system, in particular, on the structure of leukocyte formula of the African sharptooth catfish. It was found that there were no significant changes in the content of the total number of leukocytes in the blood of African catfish in case of "cytrimin" application, however, a redistribution of functionally different groups of cells in the leukogram of the African catfish was revealed. This redistribution was expressed in a slight decrease in the proportion of lymphocytes with a significant increase in the proportion of segmented neutrophils and monocytes within the physiological norm.

Enrichment of artemia with biologically active substances has three main ways - through the intestines, gills and integuments. The possibility of enrichment of artemia through the body integuments exists only for the first two days after hatching, when nauplii have soft and thin integuments. Enrichment through the intestines becomes possible only at the stage of metanauplii, which comes after the first molting when the mouth appears and the digestive system is formed. We chose enrichment through the skin of nauplii of the 1st development stage, since early nauplii are an ideal food for fish larvae at the stage of transition to exogenous feeding. The purpose of the research is to develop enrichment technology and to obtain live starting feeds with the vitalizer properties containing biologically active substances: adaptogens, probiotics, a vitamin and amino acid complex that heal the fish body, form intestinal microbiocenosis, increase growth and development rate, endurance, resistance to psychogenic and oxidative stress, increase survivability, reduce the level of cannibalism. As a result, we obtained Artemia nauplii enriched with Sporothermin probiotic, Irkutin adaptogen, Chiktonik vitamin-amino acid complex, which were used to rear larvae and fry of the African catfish. The results of the studies showed that usage of enriched nauplii accelerates fish growth, increases the proportion of "giants" with a mass more than twice the average for the population, reduces the level of cannibalism, increases survivability of fish, retaining these tendencies throughout the entire rearing period.

Measurements of the field dependences of the static magnetic susceptibility demonstrate de Haas-Van Alphen and Aharonov-Bohm oscillations at high temperatures and low magnetic fields in silicon nanosandwich structures (SNS). In the case of the deposition of DNA oligonucleotides into the edge channels of the SNS, a change in the oscillation period is observed. The possibilities of using the obtained data to identify the properties of DNA oligonucleotides are discussed.

An analysis of the advantages of laser marking is carried out in comparison with other methods of forming a given surface relief of structural materials, forming barcodes, and reading them. The necessary conditions for stable reading of barcodes, described by the value of the contrast ratio, are formulated. The elements of the prints of the laser exposure pattern that make up the barcode are classified, and an example of measuring and calculating the contrast ratio of samples using spectrophotometry is given. The parameters of the surface relief in the areas of the applied barcode are measured using scanning probe microscopy. The analysis of the influence of the parameters of laser radiation on the geometric characteristics of the elements of the barcode and the value of its contrast ratio is carried out.

In the modern market of feed and feed additives, a new trend has emerged - functional feeding complexes that heal fish, correct its metabolism, and increase productivity and quality of fish products. Such feed additives include "PRAVAD" polyvalent functional feed additive. The aim of the research was to study the effect of the new feed additive "PRAVAD" on parameters of fish antioxidant system. In order to accomplish this, two groups of sexually mature African catfish were formed. The first experimental group received PRAVAD feed supplement containing probiotics, adaptogens, essential amino acids and vitamins. It was used in addition to the main diet - "Som" feeds of LimKorm company. The control group, which was the second, received only LimKorm “Som” feed. Three months later, the content of glutathione (GSH) and the activity of glutathione-S-transferase (GST) were examined. As for fish reared with application of "PRAVAD" polyvalent functional feed additive, the GSH level of males was two times higher than that of the fish of the control group. GST activity in the group of males and females fed with the feed additive was more than 30% higher than in fish of the control group. The obtained results indicate that application of "PRAVAD" polyvalent functional feed additive in the diet of African catfish is highly effective and leads to a decrease of the damaging effect of oxidative stress. This mechanism is realized by increase of glutathione level and glutathione-S-transferase activity, both of which increase resistance to free radical and peroxide processes.

The work is devoted to study of influence of African catfish age on reproductive ability and viability of its offspring. The problem is relevant, since the issues of age selection of producers have developed relatively recently in industrial aquaculture and have not been enough studied yet. As for practical fish farming, specialists often face the problem of low quality of fish gametes that are too young or old enough. The aim of the study was a comparative assessment of the age-related variability of reproductive ability and viability of African catfish offspring. African catfish breeders at the age of 12, 24, 48, 60 months were selected for the research, four experimental groups were formed. The parameters of fertility and the quality of reproductive products, linear and weight growth of the offspring, as well as its viability were studied. The results of the study showed age-related changes in the quality of reproductive products, embryos developing from them, and subsequent larvae. Differences in egg fertility, viability of embryos and larvae, and the size of larvae obtained from producers of different ages were established. All parameters indicate that the parents’ age significantly affects the quality of their offspring. As for study of reproductive products of female African catfish of different ages by a number of parameters, such as size and diameter of eggs, certain differences were established in morphometric and physiological parameters of eggs and sperm. The study of the effect of parental age on offspring survival rate in embryonic and postembryonic periods showed that the offspring survival rate of first spawning females was the lowest and increased as the parental individuals matured. The viability of offspring in middle-aged groups of breeders was the highest.

The article is devoted to development of aquaculture of Artemia (A. Salina). Decapsulated eggs and live Artemianauplii, which have a high nutritional value and a necessary set of biologically active substances, are widely used in cultivation of fish larvae. Biological characteristics of Artemia, such as rapid growth, high fecundity, the amount of cysts that are preserved and stored, contributed to its commercialization. The demand for Artemia eggs is growing from year to year in the world market, but the volume of their production in natural reservoirs supplies only 40% of the demand. The missing volumes of Artemia can be satisfied by artificial reproduction in aquaculture. The purpose of our research was to assess the factors that regulate the ontogeny and productivity of A. Salina in aquaculture. The results of the research showed that the cultivation conditions we created, such as270Ctemperature, illumination intensity of 1500 lux, saturation of the environment with oxygen (SO2) - 90%, pH 8.2,provided 82% hatching of nauplii within the first day, and the hatching increased and reached 96-97% on the second day. Experimentally selected abiotic and biotic factors that determine the effectiveness of Artemiacultivation have shown fairly good results. Analysis of literature sources and our own data showed that it is not enough to improve abiotic and biotic factors inn case of in vitro cultivationin order to obtain high productivity of Artemia, first of all, it is necessary to have high-quality material - Artemia cysts or eggs, which should belocallyproduced, cultivating Artemia in a closed cycle. Development of effective biotechnology for artificial reproduction of Artemia in vitro is of great practical importance.

Measurements of the field dependences of the static magnetic susceptibility demonstrate de Haas-Van Alphen and Aharonov-Bohm oscillations at high temperatures and low magnetic fields in silicon nanosandwich structures (SNS). In the case of the deposition of DNA oligonucleotides into the edge channels of the SNS, a change in the oscillation period is observed. The possibilities of using the obtained data to identify the properties of DNA oligonucleotides are discussed. Keywords: THz radiation, DNA identification, de Haas-Van Alphen, Aharonov-Bohm.

This work represents the characterization of materials surface before and after laser processing with macrophotography, optical metallography, and scanning electron microscopy before and after thermal exposure. The factors influencing the reliability of the laser-induced code readability have been determined as color and contrast. The range of stability of the code readability under thermal influence on the structural materials under study was determined, which allows improving the reliability of the laser-induced marking codes readability. The research objects in this paper were samples of the following materials: alloys based on copper, aluminum, and iron with laser-induced codes of various types applied on the surface. This work aimed to research the stability of laser-induced codes readability after thermal exposure using macrophotography, optical metallography and scanning electron microscopy on structural materials of various purposes before and after laser processing (when forming a binary matrix code). The research results obtained and presented in this article on the stability of laser-induced codes reading under thermal action on structural materials can be used in different fields of industry, when marking products of heavy, general, medium, and precision engineering, as well as for marking metal products and blank parts. The results of this research are also planned to be used for further analysis of the occurring damage, leading to reading errors due to mechanical and chemical influences. It is planned to evaluate the limit values of the parameters that determine the degree of degradation at which the encoding will be considered to have lost the recognizing ability. Requirements for the quality and permissible code damage will also be developed to ensure their reliable identification.

The article contains results of the research on the influence of "Sporothermin" probiotics and "Chiktonik" vitamin-amino acid complex on the processes of free-radical oxidation of lipids in the muscle tissue of fish. Three groups of sexually mature African catfish were formed. The first test group received "Sporothermin" probiotic at a dose of 2 g / kg of feed. The second group received "Chiktonik" vitamin-amino acid complex at a dose of 2 ml / kg of feed, the third group was the control and received only LimKorm "Som" brand feeds. All groups were tested for malondialdehyde content (MDA) in three months. In the control group, the content of MDA of males was 7948.71 mmol / 100 g of tissue, females - 8119.65 mmol / 100 g of tissue. Fish reared with the probiotics had the lowest levels of lipid peroxidation. Males had the MDA level of 3931.62 mmol / 100 g of tissue, and females - 4273.5 mmol / 100 g of tissue. As for the second group, which received “Chiktonik” vitamin-amino acid complex, the MDA content was lower than in the control, but higher than in the group which received the probiotics and was 4358.97 mmol / 100 g of tissue (males), and 4957.26 mmol / 100 g of tissue (females). It can be concluded that the usage of "Sporothermin" probiotics and "Chiktonik" vitamin-amino acid complex in the diet of African sharptooth catfish leads to a decrease of free radical processes, reduces the activity of lipid peroxidation, stimulates the antioxidant system, provides resistance to oxidative stress, revitalizing and increasing the vitality of the organism fish.

The aim of the work was to study red and white blood composition of African sharptooth catfish, reared with application of innovative biotechnology elements, which involve usage of a complex of biologically active components, including Irkutin adaptogen, Sporothermin probiotics and Chiktonik vitamin and amino acid complex. Irkutin adaptogen was used to increase fish organism resistance to unfavorable environmental factors. Sporothermin probiotics was applied as an immunomodulatory agent to increase immunity, reduce the negative effects of stress factors, prevent infections, and regulate microbiocenosis. Chiktonik vitamin - amino acid complex was considered as a source of vitamins and amino acids, which the fish organism desperately needs when reared in recirculating aquaculture system. The object of the study was sexually mature males and females of African sharptooth catfish. The tasks of the work included assessment of the fish blood system reaction to components of our functional feed additive. The results of the research showed that application of Irkutin adaptogen in rearing of African catfish had an activating effect on the level of erythrocytes, leukocytes and hemoglobin content in the fish blood. Usage of Sporothermin probiotics also had a conspicuous effect on the content of blood corpuscles and hemoglobin content. However, Chiktonik vitamin-amino acid complex had the strongest activating effect on blood parameters, all parameters were significantly higher than in case of application of other biologically active components. The activating effect of each biologically active component did not go beyond the physiological norm.

Seismicity is one of the natural hazards characteristic of the Russian Federation territory. Seismic effects cause significant fluctuations not only in the surface of the earth but also in the buildings located on it. As is known, each construction has its own oscillation period, and when it coincides with the predominant period of seismic impact, a resonance effect may occur, which consists in a sharp increase in the amplitude of the oscillations. The paper shows examples of the resonance effect on the calculation of expected seismic impacts.