Search

The problem of chip processing of aluminum alloy containing scandium is considered. The difficulty of remelting due to easy oxidation of the alloy components is noted. It is proposed to dispose of the shavings without transferring the metal to liquid state. The aim of the work is to construct technological scheme for the processing of waste chips of the Al—Mg—Sc alloy formed as result of machining cast billets by cutting. Results of experiments including cold briquetting, hot extrusion and drawing are presented. The mechanical properties of the product obtained according to several variants of the technological scheme are measured. The possibility of continuous drawing of semi-finished product is shown. The conclusion is made about the possibility of using the scheme in the production process.

Infectious bovine keratoconjunctivitis (IBK) - a widespread, polietiologic, acute and rapidly spreading disease of cattle. The pathology is also known as moraxellosis. The infection is manifested by fever, oppression and damage to the eyes – catarrhal conjunctivitis, purulent-ulcerative keratitis, photophobia, lacrimation, hyperemia of the vessels of the conjunctival membranes, serous-purulent discharge, opacity and ulceration of a cornea, deformity of the eyeball, painful reaction to light, partial or complete loss of vision. The disease is common to many species of ruminants around the world, including deer, bison, antelope, camels, goats, sheep, etc. In Russia, primarily cattle is affected by moraxellosis, due to its widespread distribution. The IBK is considered the most dangerous animal eye disease in the world, and gram-negative bacteria of the species Moraxella bovis and Moraxella bovoculi are considered its main pathogens. In the case of infection development, it is possible to simultaneously damage both eyes, or one of them, but at different stages of the disease. Despite the low mortality rate, infectious keratoconjunctivitis is characterized by the high morbidity and mass disposal of animals, since a significant decrease in productivity is observed in blind animals.

The processes of radiative recombination and impact ionization in light-emitting structures based on bulk semiconductors, heterostructures with high potential barriers, nanostructures with deep quantum wells, and nanocrystals with quantum dots are reviewed. It is shown that enhancement of the quantum efficiency and luminescence optical power in all the investigated structures is caused by a common physical mechanism, specifically, the creation of additional electron–hole pairs during impact ionization by hot carriers heated at the high band offset at the heterointerface under current pumping or by the multiplication of carriers in nanocrystals upon multiexciton generation under illumination by high-energy photons.

NpCdS nanocrystals are prepared by a microbial synthesis technique at the NRC “Kurchatov Institute”—GOSNIIGENETIKA. The stabilizing layer of nanocrystals consists of proteins, and the composition of the protein layer depends on the strain used in nanoparticle (NP) biosynthesis. The morphology and size, hydrodynamic diameter, zeta-potential, and luminescence properties of the biogenic NPs are investigated using electron microscopy, dynamic light scattering, and spectrofluorimetry, and the NPs are identified as quantum dots. The effects that temperature, pressure, and solvents have on the stability and luminescence intensity of biogenic NPs are studied in collaboration with the National Research Center Kurchatov Institute—IREA. For the aqueous NpCdS suspension, the dependence of luminescence intensity on the NP concentration range is established. The feasibility of incorporation and identification of NpCdS in an epoxy resin, polyimide, and polyvinyl alcohol is evaluated. Polymer nanocomposites find use in optoelectronics, biomedicine, and agriculture.

We report on the electroluminescent and I–V characteristics of the n-InAs/n-InAsSb/p-InAsSbP heterostructure grown by metalorganic vapor-phase epitaxy. In the spectral range of 0.23–0.29 eV, the high-intensity electroluminescence at a temperature of T = 77 K has been observed. The position of the maximum of the main emission band ( $$h\nu $$ ~ 0.24 eV) has shown a noticeable blue shift with increasing forward bias. Based on the investigations, a conclusion about the existence of a type-II staggered heterojunction at the InAs0.84Sb0.16/InAs0.32Sb0.28P0.40 heterointerface has been drawn, which is confirmed by the calculated energy band diagram.

Cadmium sulfide (CdS) and zinc sulfide (ZnS) biogenic nanoparticles (NPs) were produced by microbial synthesis using bacteria of different taxonomic groups: Gram-negative (Shewanella oneidensis MR-1) and Gram-positive (Bacillus subtilis 168) bacteria in a liquid medium under aerobic conditions in the presence of salts of the respective metals and sulfur. It was shown that the stabilization of nanoparticles in aqueous suspensions is due to the presence of certain protein molecules of the outer membrane of cells, that is, proteins of the families of various receptors, porins, and flagellin, on the nanoparticle (NP) surface. The effect of the protein coating on stability, luminescence, zeta-potential, hydrodynamics diameter and other physiochemical characteristics of nanoparticles was studied. Decolorization of methylene blue dye under the exposure to UV irradiation was used as a model to demonstrate the photocatalytic properties of NPsCdS. This opens the possibility of using biogenic nanoparticles in photocatalysis for industrial wastewater treatment.

At the NRC “Kurchatov Institute” – GOSNIIGENETIKA, NpCdS nanocrystals were obtained by microbial synthesis. They were stabilized with proteins, which composition is determined by the strain used for biosynthesis of nanoparticles. Biogenic nanoparticles were studied and described by size, shape, hydrodynamic diameter, ζ potential, luminescence level, and defined as quantum dots applying methods of electron microscopy, dynamic light scattering, and spectrofluorimetry. The influence of temperature, pressure and solvents on the stability of biogenic nanoparticles and the luminescence intensity was evaluated in collaboration with IREA (NRC “Kurchatov Institute”). The luminescence intensity of the aqueous suspension of NpCdS was determined depending on the range of nanoparticle concentrations. The possibility of introducing and identifying NpCdS in epoxy resin, polyimide, and polyvinyl alcohol was assessed. Polymer nanocomposites are used for optoelectronic, biomedical and agricultural applications.

A methodology for the modernization of technological processes for the hot forging of aluminum alloy forgings based on computer simulation has been developed. The modernization procedure is outlined, including the analysis of an analogous technological process, the development of a virtual technological process structure, the creation of forging and die models in the SolidWorks program, the formulation of a computer simulation problem, the input of simulation parameters, the launch and analysis of a computer technology model, and the development of recommendations for modernizing an existing process with subsequent pilot testing of technology. An example of the methodology was the die forging technology “Rack” made of 5083 alloy, which is a single-plane complex-shaped panel with stiffeners. The analysis of the technology-analogue made it possible to formulate the problem of finding the possibility of reducing operations. Temperature, speed, and power deformation modes were introduced, which were a deformation rate of 0.3 mm/s, billet-heating temperature 450 °C, and the temperature of a die 400 °C. The output was a database of the process. At the end of the virtual experiment, the technology was tested on laboratory equipment, and a comparative analysis of the two technologies was carried out, which presented the advantages of the proposed isothermal die forging technology and developed recommendations for updating the existing technology. The transition to isothermal die forging will reduce the number of passes from three to one. All this will lead to an increase in metal utilization rate from 0.44 to 0.77.

The design and technology for the fabrication of an asymmetric stepped InAs/InAs1 –ySby/InAsSbP heterostructure with an ultimate InSb content (up to y = 0.17) in the narrow-gap active region by vapor-phase epitaxy from metal-organic compounds are developed. The electroluminescence characteristics of long-wavelength LEDs based on the proposed heterostructure, which emits in the spectral range of 4.6–5.3 μm, are studied. A linear decrease in the quantum efficiency of the electroluminescence with increasing InSb content in the active layer of the LEDs obtained is revealed. The advantage of using the asymmetric heterostructure for fabricating LEDs with a working wavelength of more than 4.5 μm is shown.

We report on the unusually large blue shift of electroluminescence spectrum with increase of the drive current at 77 K in a double-barrier nanoheterostructure with a deep AlSb/InAs0.83Sb0.17/AlSb quantum well grown by MOVPE on n-GaSb:Te substrate. The rise of drive current from 20 to 220 mA led to shift of the electroluminescence spectrum maximum towards higher photon energies by 100 meV. It was shown that this effect is due to indirect (tunneling) radiative transitions between electrons in InAsSb quantum well and heavy holes localized near AlSb/p-GaSb heterointerface. Energy of radiative transition was linearly dependent on applied voltage. In the drive current range of 50–220 mA electroluminescence blue shift was accompanied by the spectrum narrowing by 40 meV and noticeable change of the spectrum shape. With rise in drive current superlinear increase of electroluminescence intensity caused by the nonlinear dependence of tunneling radiative recombination rate on transition energy was observed at 300 and 77 K.

Health preservation is one of the urgent priorities for any group of people. There is a lot of research currently underway on diagnosing and monitoring health using data from social media. In this paper, the problem of the automatic classification of users of the Russian-language social network VK.com in terms of whether they lead a healthy lifestyle is considered. To solve this problem, various types of information was collected from user profiles: text, numerical and graphic data. The users then took a lifestyle and health survey. The results of this survey were used in order to split the users into groups according to the degree of adherence to a healthy lifestyle. The survey results were used to train various binary classifiers. The best results (about 0.76 F1-score) in our experiment were shown by a model that was trained on combined features (images from users public “walls”, as well as N-gram features compiled from text from the users public “walls”). These results were achieved using the following machine learning models “multilayer perceptron”, “naive Bayesian classifier” and “k nearest neighbours”.

Asymmetric n-InAs/InAs(1 – y)Sby/p-InAsSbP heterostructures with a narrow-gap active layer and a composition range y = 0.09–0.16 were grown by vapor phase epitaxy from metalorganic compounds. Room-temperature electroluminescence was observed at a wavelength of up to λ = 5.1 μm at a spectral maximum. The study of low-temperature electroluminescence spectra provided the possibility to establish the existence of two radiative recombination channels caused by the nature of the InAsSb/InAsSbP heterointerface. The effect produced by the chemistry of the active layer on the composition of the grown barrier layer and the formation of the InAsSb/InAsSbP heterojunction with an increase in the antimony content in the InAsSb solid solution was demonstrated.

Asymmetrical double InAs/InAsSb/InAsSbP heterostructures are grown by metalorganic vapor phase epitaxy. Two types (A and B) of light-emitting diodes with wavelengths of 4.1 and 4.7 μm at the emission-spectrum maximum are formed from these heterostructures. The room-temperature I–V and electroluminescence characteristics of the light-emitting diodes are investigated. The emission powers of light-emitting diodes A and B in the quasi-continuous mode (at a frequency of 512 Hz) at a current of 250 mA are 24 and 15 μW, respectively. In the pulsed mode (at a frequency of 512 Hz and a pulse length of 1 μs), the emission powers of light-emitting diodes A and B at a current of 2.1 A reach 158 and 76 μW, respectively. The developed light-emitting diodes can be used as high-efficiency emission sources in optical absorption sensors for detecting carbon dioxide and monoxide gases in the atmosphere.

This article presents first tephrochronological data on the volcanic activity in the valley of the Jom-Bolok River (East Sayan Mountains, Siberia), which is the largest manifestation of the Holocene eruptions in Central Asia. The data results from our study of the proglacial Kaskadnoe-1 Lake situated near the Jom-Bolok basalt field. The lake sediments include a series of tephra-rich layers. Radiocarbon dating of the lake sediments provided a robust age model which allowed us to build timing of eruptions formed the Jom-Bolok volcanic field. We recognize two large phases of volcanism separated by almost 5 thousand years dormant phase. The first phase is traced back to ca. 14.3 cal ka BP and lasted until 6.3 cal ka BP. Ten clusters of microtephra layers in the sediments of the first phase show 300-800 years recurrence of the volcanic events weakening upward. The event of 14.3-13.3 cal ka BP probably represents the strongest eruptions of the Jom-Bolok. The second phase started ca. 1.6 cal ka BP and highly likely continues in our days. Its strongest eruptions occurred between 1.6 and 0.8 cal ka BP with periodicity of 200 years. This tephrostratigraphy shows a multiplicity of the Jom-Bolok volcanic events and amplifies the earlier built scheme resulted from investigations of the stratified basalts, pyroclasts and lake damming events.

The first results of tephrochronological studies of Late Pleistocene–Holocene volcanic eruptions in the Zhom-Bolok River valley (Eastern Sayan) are reported. Based on the analysis of bottom sediments of the glacial lake Kaskadnoe-1, a detailed chronological scale of volcanic activity in this region has been worked out. It is established that the eruptions began at least 14 300 years ago and continued, gradually weakening, to 6280 years ago. In this period, ten groups of peaks of sediment enrichment in microtephra are registered for Kaskadnoe-1 Lake. The average interval between the stages of eruptions in this period was ~500–600 years. Between 14 300 and 13 400 years ago, the most large-scale volcanic events took place, eruptions were practically not interrupted, and the explosive activity was the most intense. The volcanic activity in the region in the period between 6280 and 2000 years ago is characterized by a relative rest. Later, eruptions resumed reaching peak values 1150 years ago and completing 800 years ago.

The electroluminescent characteristics of a type-II n-GaSb/n-InAs/p-GaSb heterostructure with a single deep quantum well grown by metalorganic vapor-phase epitaxy are investigated. The energy-band diagram of the structure and the positions of the electron and heavy-hole energy levels are calculated. The analysis of the current–voltage characteristics demonstrates that the dark current in the structure under study flows via the tunneling mechanism. Intense electroluminescence characterized by a weak temperature dependence was observed in the spectral range of 3–4 μm at T = 77 and 300 K. The main electroluminescence band (hν = 0.40 eV at 77 K) corresponds to direct radiative transitions between electrons from level E1 in the InAs quantum well and heavy holes from the continuum at the n-GaSb/n-InAs heterointerface. A low-intensity electroluminescence band at hν = 0.27 eV (T = 77 K) originates from indirect (tunneling) transitions from the first electron level in the quantum well to the second level of heavy holes localized in the valence-band “notch” at the n-InAs/p-GaSb heterointerface.

The article reveals the author’s position on the goals of education in the context of the development of a dialogue of cultures and global crises of our time. While considering the problems of European multiculturalism, the conclusion is made: what is good for one culture can be unacceptable and even destructive for another. In the context of considering global crises and possible comprehensive disasters, the emphasis is on the fact that the world’s population is now facing an increasingly acute problem of survival, forcing people to seriously rethink some of the priorities and values that are established in a civilized society. It is noted that the difference between the communist and capitalist ways of social development, which had been at war in the XX century, consists only in the economic and political mechanisms that determine the movement towards the same goal: satisfying the constantly growing consumer demands of the population. The author poses the question: “Is this goal true?” The article provides a rationale and a conclusion that the global strategic goal of modern education is to rid people of consumer psychology that has been formed over the centuries. People need to pay close attention to the moral side of their being and finally recognize the priority of spiritual values over material values.

The article considers an approach to assessing the indicator of protection of the population in an emergency situation at chemically hazardous facilities, leading to chemical contamination of the territory in a residential area, as well as the further development of this approach. The basis of this indicator is a numerical indicator of the toxic dose in an accident at a chemically dangerous object received by a person inside a residential building in comparison with a person outside buildings or premises. Based on the distribution of the toxic load and the comparison of its values with the studied indicator, the procedure for constructing an estimated scale of the security indicator is revealed, with the possibility of determining intervals for a qualitative assessment of the quantitative values of the security indicator.

We develop and test a flow diagram of the process of manufacturing of rods and wires from graded loose chip wastes of eutectic silumin based on the use solely of the procedures of plastic working and heat treatment. In its realization, we use the method of combined rolling–pressing of preliminarily briquetted chips with subsequent drawing of pressed rods. The possibility of getting semifinished and finished products with higher levels of strength and plastic properties as compared with cast silumin is demonstrated. The specific features of formation of the structure of the material after the realization of individual stages of the general flow diagram are indicated.

GaSb/GaAlAsSb uncooled photodiodes for the 1.1–1.85 μm spectral range are fabricated and studied. A unique method for the growth of GaSb from lead solution-melts makes it possible to obtain a low carrier concentration in the active region: n = 2 × 1015 cm–3. The capacitance of the photodiodes is 70–110 pF for a sensitive -area diameter of 300 μm and 150–250 pF for a diameter of 500 μm. The photodiodes are characterized by a high (for GaSb devices) spectral sensitivity Sλ = 0.95 A/W at the maximum, a relatively low reverse dark current density j = (4–9) × 10–3 A/cm2 at Urev = 1.0–2.0 V, and high-speed performance (response time 5–10 ns).

Significant photocurrent/photoconductivity amplification is observed at low reverse biases in a type-II n-GaSb/InAs/p-GaSb heterostructure with a single quantum well (QW), grown by metal-organic vapor phase epitaxy. A sharp increase in the photocurrent by more than two orders of magnitude occurs under exposure of the heterostructure to monochromatic light with a wavelength of 1.2–1.6 μm (at 77 K) and the application of a reverse bias in the range 5–200 mV. The optical gain depends on the applied voltage and increases to 2.5 × 102 at a reverse bias of 800 mV. Theoretical analysis demonstrated that the main role in the phenomenon is played by the screening of the external electric field by electrons accumulated in the deep InAs QW and by the mechanism of the tunneling transport of carriers with a small effective mass. It is shown that the effect under study is common to both isotype and anisotype type-II heterojunctions, including structures with QWs and superlattices.

n-GaSb/n-InAs/p-GaSb heterostructure with a single InAs QW was grown for the first time by MOVPE. Photocurrent spectra were obtained at reverse bias in the range from 0 to 0.8 V. It was shown that the photocurrent increases nonlinearly. The maximum of differential photoconductivity is archived at low applied voltage up to 0.2 V. This effect was explained by electrostatic screening of electrons localized in QW.

Expression of inducible NO-synthase mRNA and myocardial infiltration with neutrophils were studied in rats with modeled permanent ischemia and ischemia/reperfusion models. Expression of inducible NO synthase mRNA in the ischemic region increased significantly in 3, 3.5, and 4 h in modeled ischemia/reperfusion and in 3.5 and 4 h in permanent ischemia. Myocardial infiltration with neutrophils was significantly higher than in intact controls throughout the experiment without significant intergroup differences. In non-ischemic myocardium, enhanced expression of inducible NO synthase mRNA and moderate neutrophilic-lymphocytic myocardial infiltration were also observed in 3.5, and 4 h after ischemia.

In March 2014, the Lake Baunt bottom sediments were drilled in the deepest part of the lake basin (33 m). The penetrated interval is 13.7 m thick, with the age of the base being evaluated at 28–30 ka. Lithological study of the penetrated sediments demonstrates the upper part of the section dominated by diatom ooze, whose concentration decreases gradually downward the section, up to the replacement of the ooze by silty clay. The obtained data on variations in petromagnetic parameters, concentration of biogenic silica, and sediment compaction indicate considerable variations of sedimentary environments during the Late Pleistocene and Holocene. Being compared with the previously reconstructed landscape and climate dynamics for the sedimentary succession of Lake Kotokel for this time interval, the above parameters reveal that the Lake Baunt bottom sediments reliably fix the regional paleoclimate signal. For the first time for lakes of the Baikal region, Gothenburg and Mono Lake magnetic excursions are identified in the paleomagnetic record of the Lake Baunt section.

In the article discusses the results of laboratory tests coal ash and slag mixture from the ash pound of Omsk’sTPP-4, working on the Ekibastuz coal.In the course of these studies identified the deformationproperties of this man-induced soil depending on the degree of compaction and moisture content. Suitability as a soil material for the construction embankments, subgrade of roads, and as the Foundation of buildings and structures was evaluated. The empirical dependence of the properties of ash and slag mixture from moisture and maximum dry density had been obtained in this research. Comparison of strength characteristics of ash and natural soil from our region also was carried out.