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The effect of carbon (3 wt %) on the electrical resistivity of alloys based on aluminum nickelides Ni–Al and Ni–Al–C synthesized by electrothermal explosion in the temperature range of 300–1300 K in a vacuum of 2 × 10–3 Pa has been studied. At an electrothermal explosion in a powder reaction medium, a Ni–Al-based melt is formed in which carbon dissolves. It is shown that, during the crystallization of the final product, due to its low solubility in Ni–Al, carbon is located at the boundaries of intermetallic grains of Ni–Al in the form of multilayer graphite nanofilms 50–80 nm thick, filling the intergranular space. It is shown that the synthesized alloys have a metallic character of conductivity, and the electrical resistivity in the measured temperature range of 300–1300 K increases monotonically for Ni–Al from 16 to 40 μΩ cm and for the carbon-bearing alloy Ni–Al–C from 22 to 60 μΩ cm. In this case, an increase in the temperature coefficient of resistance (TCR) is also observed from 1.45 × 10–3 K–1 for Ni–Al to 1.77 × 10–3 K–1 for Ni–Al–C. The slope of the curves of the dependence of electrical resistance on temperature in the studied temperature range of 300–1300 K remains constant and is well described by a linear function.

—A theoretical analysis of various single-sideband modulation formats used in fiber-optic communication lines with an external electrooptical two-electrode Mach–Zehnder modulator for generating optical signals resistant to dispersive power degradation has been performed. A family of new single-sideband modulation formats is presented, the features of their use, advantages, and disadvantages are considered. A decrease in nonlinear distortions of signals during their transportation through dispersive optical fiber is assumed.

This work is devoted to the description of a new design solution for the gas distribution mechanism of a reciprocating compressor. The study of the factors that have a significant effect on the vibration and noise performance of hermetic refrigerant compressors allows the authors to conclude that the world leaders in the cost and sales of compressors are manufacturers whose products have a sound power level in the range of 32-36 dBA. The authors propose a new design solution for a unified valve plate for use in a parametric range of hermetic piston refrigerant compressors of the SKO series. The proposed valve train contains a 1.015 mm thick composite valve plate containing five 0.203-mm Sandvik 20-C valve steel plates that are bonded with anaerobic adhesives. Laboratory studies revealed the advantages of S-KO compressors in terms of the average sound power level at 4.8-5.54 dBA; supply coefficient (refrigeration coefficient) decreased by 27.4 ÷ 14.4%. Such results were achieved due to the use of anaerobic adhesives, which made it possible, instead of a machined valve plate, to use a composite 1.015 mm thick and provide a stronger contact between the surfaces of the plates.

A composite material based on the Ni–Al–C system is synthesized by the method of an electrothermal explosion at a pressure of 96 MPa. During the electrothermal explosion in a reactive powder medium (Ni + Al + C), a Ni- and Al-based melt is formed, in which carbon dissolves. In the process of crystallization of the final product, carbon, due to its low solubility in NiAl, is located on the surface of intermetallic grains of NiAl in the form of multilayer graphite nanofilms 50–80 nm thick and fills the intergranular space. The microhardness of the synthesized material is 3084 MPa.

Problems associated with the radiography of objects made of steel having thickness of 100 mm and more are outlined. The classical method of gathering information provides for mounting semiconductor photo detectors directly on scintillators. As a result, gamma radiation scattered in a scintillator enters photo detector increasing the image noise and providing a negative effect on processing electronics. A method to design a recording system using a wavelength-shifting fiber having no disadvantages of the classical technique is proposed. This method makes it possible to decrease the image noise, to remove electronics from direct effect of gamma radiation and to increase the registration efficiency. Various approaches of implementing the method proposed to detect signals are explored experimentally with selecting the optimal techniques. This research enabled developing a design base to engineer recording element. The results on measuring parameters of the registering element are presented.

Aim. Production of recombinant viral antigens of the main immunodominant proteins: glycoprotein (GPΔMLD), nucleoprotein (NP) and matrix protein (VP40) of the Marburg virus, as well as the study of their antigenic and immunogenic properties.Materials and methods. To create recombinant proteins GPΔMLD, NP and VP40 of the Marburg virus, synthesized nucleotide sequences encoding these proteins cloned into the pET21a expression vector were used. The immunogenic and antigenic properties of the obtained recombinant proteins were tested using a number of biomodels (mice, chickens, and guinea pigs).Results and discussion. Recombinant plasmids containing genes encoding proteins GPΔMLD, NP, VP40 of the Marburg virus, as well as Escherichia coli producing strains, with the yield of purified preparations of recombinant proteins GPΔMLD, NP, VP40 from one liter of culture fluid – 5, 10, and 10 μg were obtained, respectively. When mice are immunized, recombinant proteins GP, NP, and VP40 MARV induce the synthesis of high titer antibodies (recombinant proteins NP and VP40 – more than 409600, and recombinant protein GPΔMLD – 12800). Mouse antibodies specific to recombinant proteins interact in an enzyme-linked immunosorbent assay (ELISA) with the antigen of inactivated MARV. Antibodies of chickens immunized with virus-like particles containing the surface glycoprotein of the Marburg virus and antibodies of guinea pigs immunized with an experimental DNA vaccine containing the GPΔMLD MARV gene recognize the recombinant GPΔMLD protein and the viral protein in the inactivated MARV. The resulting recombinant proteins are immunogenic/antigenic and can be used for the development of enzymelinked immunosorbent assay systems.

The preparation and study of the biological properties of the pVAKS-GPVM DNA immunogen containing a gene encoding Marburgvirus glycoprotein are described. The specificity of blood serum antibodies of guinea pigs immunized with DNA immunogen was analyzed by ELISA. Inactivated viral preparation, recombinant glycoprotein (GP) obtained in the prokaryotic system and virus-like particles based on the recombinant vesicular stomatitis virus exhibiting Marburgvirus GP were used as the antigens. The neutralizing activity of antibodies of immunized animals was tested in vitro using a pseudovirus system. It was demonstrated that the developed immunogen administered to guinea pigs induced the production of specific antibodies that neutralize virus-like particles and Marburgvirus in cultured Vero cells.

The aim was to study the possibility of inducing Marburg-neutralizing chicken antibodies (MARV) using various immunogens.Materials and methods. Recombinant vaccinia virus expressing the surface glycoprotein (GP) transgene MARV of Musoke strain and pseudovirus particles exhibiting GP of three strains of MARV – Popp, Musoke and DRC2000 based on lentivirus and recombinant strain of vesicular stomatitis virus (VSV) were used as immunogens. Two groups of birds were involved in the study. Chickens were immunized 9 times: first time they were injected with the recombinant vaccinia virus, and then 8 times – with pseudovirus particles (based on lentivirus and a recombinant strain of the vesicular stomatitis virus). The accumulation of specific antibodies was evaluated by enzyme-linked immunosorbent assay (ELISA). We used recombinant VSV exhibiting GP MARV, and natural MARV strain Popp for the analysis of accumulation of neutralizing antibodies.Results and discussion. We have developed an effective immunization schedule for chickens with three recombinant constructs presenting GP MARV, which results in the induction of chicken IgY antibodies against Marburg virus with a titer in ELISA from 1:100 to 1:1 million. The obtained IgY neutralize MARV pseudoviruses (Popp, DRC2000, Musoke) at a dilution of 1/256 to 1/1024 and the natural MARV virus of the Popp strain at a dilution of 1/8. More stable results were demonstrated by immunization using Freund’s incomplete adjuvant.

A step-by-step scaling-up of the production of recombinant human granulocyte-macrophage colony-stimulating factor has been carried out. The tenfold expantion of the technology made it possible to obtain 5 mg of the target protein with a purity of more than 96% from 1 g of wet cells. The produced protein series meets the requirements for recombinant proteins of the XIV edition of the State Pharmacopoeia of the Russian Federation. Conjugates of recombinant human granulocyte-macrophage colony-stimulating factor with dextran and molecular construct of the conjugates and double-stranded RNA were obtained. The adjuvant activity of the resulting preparations was shown in different models. Key words: granulocyte-macrophage colony-stimulating factor, chromatography, molecular construct We express our gratitude to the staff of the Laboratory of Immunochemistry of the SRC VB Vector N. V. Volkova, M. B. Borgoyakova, A. A. Isaeva and S. V. Belenkaya for assessing immunogenicity in the RBD model.

In this article, we present GaAs millimeter-wave pseudomorphic high-electron-mobility transistor (pHEMT) using sophisticated AlGaAs-InGaAs–GaAs heterostructure with an In0.22Ga0.78As quantum well located inside an external quantum well formed by space charge regions in AlGaAs layers. In a heterostructure with this design, high mobility [5800 cm2/( $\text {V}\cdot \text {s}$ )] and high density ( ${4.7}\times {10}^{{12}}$ cm $^{-{2}}$ ) of two-dimensional electron gas at 300 K were obtained. The localization of hot electrons in an external quantum well leads to an increase in their drift velocity and to enhance the dc and RF performances of the device. A field-effect transistor based on such a heterostructure with a T-gate of $0.14~\mu \text{m}$ in length shows a specific current density of about 0.7 A/mm, transconductance of about 250 mS/mm, gate–drain breakdown voltage in the range 23–31 V, which corresponds to more than 2 W/mm specific output RF power according to a simple estimate. The transistor demonstrates impressive RF characteristics, the maximum stable gain (MSG) of more than 15 dB at 40 GHz and more than 10 dB at 67 GHz, ${f}_{t} = {45}$ GHz and ${f} _{\text {max}} = {250}$ GHz. The MSG at 40 GHz increases with increasing distance between the gates in the drain and is almost constant in the range 25–55 GHz.

Objective The aim: Of the research is to study of the stress distribution in the "bone-implant" system for various cases of elbow flexion and semipronation in the event of the radial head arthroplasty with the developed bipolar radial head (RH) implant and the bipolar KPS endoprosthesis. Patients and methods Materials and methods: We developed a metal-metal bearing bipolar RH endoprosthesis providing an uncemented fixation due to a special porous coating and stem design. Using Solid Works software, we developed a geometrical model of the elbow joint with cartilaginous surfaces. Then, to refine the parameters of the finite-element model, calculation and visualization we transferred the model to the ANSYS complex. Results Results: The developed bipolar RH endoprosthesis with metal-metal bearing is a stiffer construction compared to the KPS endoprosthesis. However, the displacement fields in the joint and the value of arising maximum strains in the "bone-implant" system with the RH endoprosthesis have a smaller deviation from the strains arising in the healthy elbow joint than those in the "bone-implant" system with the KPS endoprosthesis. Conclusion Conclusions: The developed bipolar RH endoprosthesis does not cause any critical impacts on the joint surfaces and ligamentous apparatus of the elbow joint. All the elements of the developed bipolar RH endoprosthesis satisfy the requirements of an operative structure strength and stiffness. Strain fields arising in the bipolar RH endoprosthesis have a smaller deviation from the strains in the healthy joint in comparison with those occurring in the "bone-implant" system with the KPS endoprosthesis.

The electromechanical model for analyzing a homopolar electric motor with a magnetic system made using second-generation high-temperature superconductors (HTSC 2G) is described. Homopolar electric motors made with a disk-shaped rotor have the simplest design of their magnetic system and heavy-current contact. Owing to the use of HTSC 2G conductors for producing constant magnetic field in the rotor area, it becomes possible to achieve a higher current density in the windings, thereby increasing the motor power capacity. Due to the HTSC ability to operate at the liquid nitrogen temperature (77 K), it becomes possible to have a simpler cryostat design in comparison with magnetic systems based on low-temperature superconductors. For large-capacity homopolar motors, the use of liquid metal contacts for supplying current to the rotating rotor seems to be the most promising design solution. The advantage of motors of this type is that their torque depends linearly on the rotor current. The homopolar motor operation governed by a proportional-integral-differentiating (PID) controller was simulated using the SciLab Xcos software. The application of the analysis model for selecting the optimal PID-controller coefficients is demonstrated. The electric motor dynamic operation modes are analyzed. The numerical simulation results are compared with the previously obtained experimental data.

A pSVB-Cer plasmid vector has been developed that allows integrating an expression cassette containing the maral prochymosin gene into the genome of the commercial strain GG799 of the Kluyveromyces lactis yeast. Controlled expression of the maral prochymosin gene in the recombinant producer was achieved using a hybrid auto-inducible P350 promoter, which is activated in the absence of glucose in the culture medium. This promoter included a 3ʹ-fragment of the core sequence of the promoter of glyceraldehyde-3-phosphate dehydrogenase (GAP1) and a 5ʹ-fragment of the regulatory sequence of the promoter of isocitrate lyase (ICL1). As a selective marker, the gene of acetamidase (amdS) controlled by the promoter of the gene of alcohol dehydrogenase (ADH1) was introduced into the pSVB-Cer vector. Producer clones, which ensure the accumulation of recombinant maral prochymosin in the culture medium, were obtained. The influence of the initial glucose concentration, temperature, cultivation duration, as well as amounts of phosphoric acid salts and B group vitamins on the level of the target pro-enzyme accumulation in the culture fluid was established. The maximum yield of recombinant maral chymosin with an activity of 152 U/ ml was obtained by cultivating the producer strain for 114 hours at 22 oC in a medium containing 3% glucose, 0.75 g/l potassium hydrophosphate and 4.5 mg/l calcium pantothenate. Key words: recombinant maral chymosin, milk-clotting activity, producer, hybrid auto-inducible promoter, Kluyveromyces lactis The work was performed within the framework of the state task of the Ministry of Science and Higher Education of the Russian Federation (topic number FZMW-2020-0002, "Development of Recombinant Enzyme Producers for Cheese Making") and by financial support of Russian Foundation for Basic Research and the government of NSO according to the research project №19-44-543018

In this paper we consider the problems arising in the numerical estimation of the ultimate load of welded joints of high-strength steels with slight hardening. The stress concentrator in the transition node from the deposited to the base metal is modeled based on the example of welding a roller wire on a plate made of high-strength steel. The use of welding wire with a yield point lower than that of the base metal allowed to simulate areas of the welded joint with heterogeneous mechanical properties. The geometry of three areas of the welded joint is studied, i.e. weld metal, heat-affected zone (HAZ) and the base metal. Mechanical properties of all three areas are determined by calculation and experimentally. For this purpose, it is proposed to consider the material in all sections as ideally elastic-plastic, and the yield strength is uniquely associated with the hardness in the indentation zone (a Rockwell diamond cone is used). Calculations of the inelastic indentation process by the finite element method (FEM) in axis-symmetric formulation allowed obtaining a linear relationship between the hardness and the yield strength with a coefficient of 0.418. Tests at a quasi-static three-point bend (with stretching in the surfacing area) were carried out on sample beams cut perpendicular to the direction of welding. The “force-deflection” diagrams are obtained and compared with the calculated curves (FEM in a three-dimensional formulation with an explicit consideration of the complex configuration of all sections and different yield stress in the areas determined by local hardness values). There is a good agreement between the calculated and experimental ultimate loads. The proposed method of the three-stage study (determination of local hardness, yield strength in the areas and the ultimate load) can be effectively used to assess the ultimate loads of the welded joints due to the low parametricity of the proposed models of materials inelastic deformation in areas for which it is impossible to manufacture standard samples for the study of mechanical properties. The experimental study of the strengthening effect of the seam with a stress concentrator in the form of an angle of 90 degrees on the value of the ultimate bending load showed that the removal of the deposited metal does not lead to an increase in the ultimate load of the welded joint when using the welding wire of low-carbon high-plastic steel.

Mesoporous C, S-doped TiO2 nanostructures were obtained by solvothermal sol-gel method followed by calcination at different temperatures. It was found that with increasing calcination temperature, the crystallite size remains in the same range of 9–10 nm, while the morphology of TiO2 nanoparticles significantly changes, and the anatase content increases from 42% to 95%. At the same time the nanoparticle size (from 85 to 45 nm), the specific surface area (200–130 m2/g), the mesoporous area (from 170 to 70 m2/g), and the carbon (0.80–0.41%) and sulfur (1.39–0.89%) contents decrease. Varying the calcination temperature allows TiO2 nanostructures to be obtained with a certain balance of these structural-dimensional characteristics that provides high photocatalytic activity in the processes of ceftazidime and doxycycline photodegradation.

The paper reports on the production of the maral recombinant chymosin in the Escherichia coli expression system (SHaffle express strain) and the study of its biochemical properties relevant for the cheese-making industry. The highest maral recombinant prochymosin content in inclusion bodies was observed when producer cells were cultured at 25°C for 6 h after the introduction of an inducer, 10 mM isopropyl-β-D-1-thiogalactopyranoside. The biochemical properties of the obtained enzyme were compared with those of bovine and dromedarian recombinant chymosins. It is shown that total proteolytic activity of the maral recombinant chymosin was comparable with that of the bovine enzyme and that it exceeded the activity of the dromedarian enzyme by about 3.8 times. The thermal stability of the recombinant chymosin from maral was found to be 5–10°C higher than that of the chymosins from the cow and dromedary. The patterns of dependence of milk-clotting activity on the pH level and calcium chloride concentration in cow’s milk on the enzyme from maral met the requirements set by the cheese industry. Its high proteolytic activity and thermal stability limits the scope of application of maral recombinant chymosin to the production of cheeses with short ripening and short storage times.

The compression and burning of a fusion target ignited by a focused shock wave produced at the action of a time-profiled second harmonic laser pulse of a Nd laser have been calculated and theoretically studied. The main energy features of the shock ignition scheme have been considered. The use of the second harmonic radiation corresponds to a higher energy and a longer laser pulse necessary for ignition by this method compared to the use of the third harmonic radiation. Nevertheless, the method of ignition by the focused shock wave with the second harmonic radiation makes it possible to reach the fusion target gain that is two or three times higher than that at the traditional spark ignition with the laser pulse energy higher than in the former case by a factor of 1.5. The numerical calculations have been performed with one-dimensional hydrodynamic codes.

The experimental study of the high-temperature interaction kinetics of a titanium-soot mixture under quasistatic compression in an electrothermal explosion (ETE) is described. Dependences of the heating rate of a sample mixture on temperature are obtained, and the effective values of the energy of ignition activation and thermal explosion are calculated. The formation of the microstructure of intermediate and final interaction products is investigated. It is shown that the formation of a final product occurs according to a shell-core mechanism. The high rate of the solid-phase interaction of titanium and soot is explained by the formation of micropores and microcracks in the intermediate product, which ensure the high rate of surface diffusion of carbon.

The study of an electrothermal explosion (ETE) of a titanium—soot mixture under quasistatic compression is described. Experimental dependences of thermal and electric parameters of the ETE on the power of electric heating are obtained. It is shown that the heating rate of a reacting mixture significantly affects the ignition temperature and maximum temperature of the ETE. It is determined that, at the stage of pre-explosion heating, the electric resistance of the mixture decreases by 90—95%, and the rate of the temperature rise during a thermal explosion is independent of the heating rate of the mixture. A technique for determining the ignition time and temperature, based on measuring the thermal and electric parameters of the ETE. Liquid-phase and solid-phase interactions in the titanium—soot mixture powders are discussed.

The review discusses the basic biochemical properties of the known recombinant chymosins that are currently used in cheesemaking or may potentially be used as industrial milk coagulants. The parameters of the Michaelis–Menten kinetics, milk-clotting activity, proteolytic activity, specificity, and the dependence of coagulation ability on pH and calcium-ion concentration are considered.

C,S-Doped TiO2 nanoparticles with diameter 55-85 nm were obtained by a solvothermal sol-gel method with subsequent calcination; the diameter of the component crystallites was 9-11 nm. An increase in the thiourea concentration in the reaction mixture reduced the anatase content, while increasing the particle size, specific surface area, as well as carbon and sulfur contents. The photocatalytic activity of such materials in the degradation of doxycycline upon UV irradiation depends mainly on the anatase content and mesopore surface area, while such activity upon irradiation with visible light depends mostly on the presence of carbonate and sulfate groups.

For the first time, the chymosin gene (CYM) of a maral was characterized. Its exon/intron organization was established using comparative analysis of the nucleotide sequence. The CYM mRNA sequence encoding a maral preprochymosin was reconstructed. Nucleotide sequence of the CYM maral mRNA allowed developing an expression vector to ensure production of a recombinant enzyme. Recombinant maral prochymosin was obtained in the expression system of Escherichiacoli [strain BL21 (DE3)]. Total milk-coagulation activity (MCA) of the recombinant maral chymosin was 2330 AU/ml. The recombinant maral prochymosin relative activity was 52955 AU/mg. The recombinant maral chymosin showed 100-81% MCA in the temperature range 30-50°C, thermal stability (TS) threshold was 50°C, and the enzyme was completely inactivated at 70°C. Preparations of the recombinant chymosin of a single-humped camel and recombinant bovine chymosin were used as reference samples. Michaelis–Menten constant (Km), turnover number (kcat), and catalytic efficiency (kcat/Km) of the recombinant maral chymosin, were 1.18 ± 0.1 µM, 2.68 ± 0.08 s−1 and 2.27± 0.10 µm M−1·s−1, respectively.

Time series of acoustic emission pulses are recorded when the surface of MgAl2O4 ceramics is damaged by the introduction of a Vickers pyramid. Based on the data of the frequency analysis of the emitted sound, the ratio of the size of intra- and intergranular microcracks is estimated depending on the load on the indenter. The statistical analysis shows that the energy distribution in acoustic pulses is always random, typical of the uncorrelated development of a fracture.

Compared with optimizing electrical filter (EF) designs and increasing field numbers, optimizing the modes of the electric power supply of corona electrodes is more economical for increasing the level of degree of dust cleaning. Moreover, the simplest and least expensive way is to change the form of the supply voltage other than unipolar by applying, in addition to any kind of standard power supply, for example, a pulse from the console of a high-voltage pulse power source (PPS) in a microsecond duration based on high-voltage power thiratrons. Numerous experiments have been performed on an EF-type EGA-35-9-5-3 with a unipolar voltage of approximately -40 kV, which is supplied by a standard unipolar power source (i.e., ATF 600). The optimal pulse duration is determined to be 20 – 60 μsec (with a duty ratio of approximately 200%), and the repetition period is approximately 4 msec (250 Hz). A study aiming for almost a ten-fold increase in the service life of PSS auxiliary devices was reduced to the development of a new electron-beam switch ELV 50/100M instead of a high-voltage power thyratron TGI1-2500/35. The parameters of the electrical circuit were optimized via computer simulation. Results showed that replacing a power thyratron switch with an electron beam does not affect the output pulse parameters of auxiliary devices. In accordance with the minimum value of chimney dust emissions and a predetermined algorithm, the electric operating modes of PSS auxiliary devices were optimized for each of the boiler’s mode of operation by using an intelligent control system. The initial data on dust emissions for the control system were determined by using an optical dust meter. The electrical circuit of an intelligent control system for the automatic optimization of the PSS auxiliary device’s mode of operation is under development. Its implementation requires further verification in the field.

Department of hydraulic engineering and hydraulics FGBNU «VNIIGiM them. A.N. Kostyakova «has a long history. For many years, the department’s staff has been such scientists and water engineers with extensive experience as M.A. Volynov, V.S. Verbitsky, S.S. Medvedev, N.V. Lebedev, B.C. Panfilov, T.G. Voynich-Syanozhentsky, V.A. Golubkova, G.V. Lyapin and others. The department solved a wide range of tasks, the main areas of research were the following: – theoretical and applied hydrodynamics and hydraulics, with reference to the open channel flows that affect the state and level of safety of the hydraulic structures; – integrated use and protection of water bodies – water sources and water sources of water resources used in land reclamation; – development of measures and technical solutions for the protection of objects from the negative effects of water; – theoretical substantiation of works to improve the safety level of the GTS (declaration); – development and implementation of digitalization methods for solving design, construction, operation and control of landreclamation facilities. Currently, promising areas of research is the development of a decision-making algorithm in the designation of measures to rationalize the provision of resources to water amelioration. The algorithm is developed on the basis of a detailed study, systematization and processing of data both on safety and on the efficiency of systems and structures, ensuring the delivery of irrigation water of the required quality and in sufficient quantity from a water source to the field.

The heating of current-limiting elements made of second-generation HTSC tapes stabilized with a stainless steel tape is studied experimentally. It is shown that the heating rate depends little on the degree of stabilization with stainless steel. Using a mathematical model that takes into account the heat sink parameters (the medium is liquid nitrogen), the capabilities and limitations of increasing the area of the current-limiting element for reducing its temperature in the current limiting mode are demonstrated.

Possibilities of increasing the electron beam energy concentration in the electron-optical system of a welding gun characterized by a traditional scheme in which a focusing lens and a deflecting system are installed sequentially along the beam and a new scheme based on a focusing–deflecting system with combined fields are considered. A technique based on solving the paraxial equations of trajectories and calculating aberration integrals is described, which allows one to determine the total diameter of the electron beam. Based on the described methodology, a model of a new focusing–deflecting system with combined fields has been developed. It is shown that the new scheme of the electron-optical system allows one to increase the energy concentration in the region of the interaction of the beam with the material in comparison with the traditional one.

In this work the design of a homopolar motor prototype is proposed. The magnetic system consists of a high temperature superconducting (HTS) stator and a disc rotor with liquid metal sliding electric contacts made of gallium indium tin alloy. The estimation of magnetic fields and torques is performed for the device. The possibility of using this motor as a servo actuator is considered. The results of the preliminary experimental attempts to control a single pole motor based on permanent magnets by means of a proportional–integral–derivative (PID) algorithm are presented.

The radiation hardness of neodymium-doped gadolinium vanadate crystal (Nd:GdVO4) has been investigated. Crystal with sizes of 4×4×8 mm doped to a level of 0.5% Nd3+ and (for comparison) undoped GdVO4 crystal were γ-irradiated by a 60Co source to an absorbed dose of about 106 to 107 rad. The photoinduced absorption spectra of the crystals have been studied. Intense lasing with a differential efficiency up to about 25% was obtained in an irradiated Nd:GdVO4 crystal. It is shown that irradiation of a crystal up to a dose of 107 rad does not reduce significantly its laser efficiency.

Diseases associated with porcine circoviruses (mainly with porcine circovirus type 2) have various manifestations, are common in pigs in countries having well-developed pig industry and responsible for significant economic losses. Porcine circovirus type 3 (PCV-3) causing systemic inflammation of unknown etiology in animals was detected the USA in 2015. Later, data on PCV-3 detection in Asia, Europe and South America were published. Analysis of literature data on current epidemic situation on PCV-3 infection in foreign countries as well as the disease clinical manifestations and postmortem lesions are described. Results of molecular and genetic tests of biomaterials collected from pigs in 51 holdings located in 28 regions of the Russian Federation are presented. A total of 280 samples of biological materials of different types (organs, tissues, stillborn piglets) collected from domestic pigs with respiratory, reproductive and neurological disorders, dermatitis and from emaciated pigs were tested and PCV-3 genome was detected in 11 samples from 9 holdings located in 5 regions of the Russian Federation. Porcine circovirus type 3 was detected in lung, bronchial and mediastinal lymph node, spleen tissues from grower and fattening piglets, adult pigs and aborted fetuses. Samples that were positive for PCV-3 DNA when tested with molecular methods (PCR, real-time PCR) were tested for other pathogens. The following pathogens were also detected in 6 out of 11 samples (55%): Actinobacillus pleuropneumoniae, Mycoplasma hyorhinis, Streptococcus suis, Haemophilus parasuis, Mycoplasma hyopneumoniae and Pasteurella multocida. Porcine circovirus type 2 was detected in one sample. Presented test results are indicative of probable combined etiology of respiratory and reproductive disorders in tested pigs that results in various clinical manifestations. Grower and fattening piglets were found to be the most susceptible to PCV-3-associated disease. Further studies are required for identification of actual PCV-3 pathogenicity and its prevalence in the territory of the Russian Federation.

Due to the conditions that cause the spread of COVID-19, national health systems worldwide are under severe strain. Most countries face similar difficulties such as a lack of medical personnel and equipment and tools for diagnosis and treatment, overrun hospitals, and forced restriction of planned medical care. Public authorities in healthcare take the following measures due to increased pressure: limiting the transmission and spread of the virus (social distancing and quarantine), mobilizing medical personnel, ensuring the availability of diagnostic and treatment tools, and providing a sufficient number of premises, which are not always suitable for the provision of medical care (buildings and structures). To date, the stages of management decision-making to counter coronavirus infection and the risk of COVID-19 transmission at various facilities have not been analyzed. The authors propose a methodology for assessing the COVID-19 transmission risk at various social and transport facilities. A survey of 1325 respondents from Moscow demonstrated the most significant risk factors, such as visitation avoidance, infection risk, and facemask wearing. Risk categories were determined and objects classified according to high, medium, and low-risk levels.

High harmonic generation (HHG) opens a window on the fundamental science of strong-field light-mater interaction and serves as a key building block for attosecond optics and metrology. Resonantly enhanced HHG from hot spots in nanostructures is an attractive route to overcoming the well-known limitations of gases and bulk solids. Here, we demonstrate a nanoscale platform for highly efficient HHG driven by intense mid-infrared laser pulses: an ultra-thin resonant gallium phosphide (GaP) metasurface. The wide bandgap and the lack of inversion symmetry of the GaP crystal enable the generation of even and odd harmonics covering a wide range of photon energies between 1.3 and 3 eV with minimal reabsorption. The resonantly enhanced conversion efficiency facilitates single-shot measurements that avoid material damage and pave the way to study the controllable transition between perturbative and non-perturbative regimes of light-matter interactions at the nanoscale., Strong nonlinearities, like high harmonic generation in optical systems, can lead to interesting applications in photonics. Here the authors fabricate a thin resonant gallium phosphide metasurface capable of avoiding the laser-induced damage and demonstrate efficient even and odd high harmonic generation from it when driven by mid-infrared laser pulses.

Oxidation decomposition of titanomagnetite grains to the magnetite–ilmenite lattice during the formation of igneous rock can lead to thermochemical remanent magnetization (TCRM). Computer simulation of TCRM in the system of single-domain interacting particles and numerical simulation of the Thellier experiments to determine the paleointensity have been carried out. Contrary to the concerns, the Thellier technique factually applied to the TCRM-bearing samples yields a result that is very close to the true value of the external magnetic field applied to the sample during formation of the TCRM. Together with the recently published laboratory experimental data, these calculations are indicative of a good perspective for obtaining reliable paleomagnetic data on TCRM-bearing samples and can expand the class of rocks suitable for determination of the paleointensity.

Study review is given for mathematical models dedicated to induction motor non-symmetrical modes research. Papers are reviewed, featuring mathematical models based on magnetic-coupled electrical circuits theory, magnetic circuits theory, symmetrical components method. The article works out the possibility of studying various complexity non-symmetrical modes of induction machine. The conclusions and the summaries describing differences and peculiarities of these approaches are also formulated.

It is a common current practice in ophthalmology to use laser for coagulating deep-lying tissues. Laser techniques are sufficiently simple and accurate to be used in outpatient settings. Despite a limited penetration depth, laser coagulators are also widely used for treating corneal pathologies. The article discusses the therapeutic use of a 1.43-μm laser coagulator.

We report an experimental study of the effect of laser irradiation of aqueous salt solutions containing the 152Eu isotope in the presence of nickel nanoparticles on the gamma activity of the isotope. Nickel nanoparticles are generated using laser ablation of the target in water and added to the radionuclide solution before irradiation. Two types of Nd : YAG lasers with a pulse duration of 10 ns and different repetition rates are used to irradiate the solutions. It is found that the 152Eu activity as a result of repeated irradiation of solutions by a series of pulses decreases with each irradiation cycle. The obtained results are compared with data on the effect of maser radiation with a wavelength of 8 mm on the activity of the same isotope. Possible mechanisms of the effect of electromagnetic radiation on the 152Eu gamma activity are discussed.

A method for the production of pure solutions of hydrogen peroxide during water activation by the plasma of electrodeless microwave discharge has been developed. It is shown that activated water has a pronounced effect on agricultural plants, being a non-toxic and chemically pure regulator of biological activity. In particular, the treatment of seeds of agricultural plants with activated water solutions can improve their drought resistance.

Time-dependent nonlinear media, such as rapidly generated plasmas produced via laser ionization of gases, can increase the energy of individual laser photons and generate tunable high-order harmonic pulses. This phenomenon, known as photon acceleration, has traditionally required extreme-intensity laser pulses and macroscopic propagation lengths. Here, we report on a novel nonlinear material—an ultrathin semiconductor metasurface—that exhibits efficient photon acceleration at low intensities. We observe a signature nonlinear manifestation of photon acceleration: third-harmonic generation of near-infrared photons with tunable frequencies reaching up to ≈3.1ω. A simple time-dependent coupled-mode theory, found to be in good agreement with experimental results, is utilized to predict a new path towards nonlinear radiation sources that combine resonant upconversion with broadband operation., Photon acceleration, which can be used to generate tunable high harmonic radiation, typically requires high-intensity lasers and long propagation distances. Here, Shcherbakov et al. show efficient photon acceleration at low power input power from a semiconductor metasurface, less than a micron thin.

To feed a pulse modulator with quickly changing pulse duration, it is necessary to have a power supply source that will ensure voltage stability at uneven energy consumption due to rapid changes in pulse duration. A pulse modulator is an electrical device designed to convert the energy of mains-frequency voltage to the energy of high-voltage pulses. The power supply source wiring diagram compliant with energy-saving requirements consists of an adjustable mains rectifier, a primary energy storage adjusted by pulse-width modulation (PWM), a high-frequency (HF) bridge inverter, a stepup transformer, a high-voltage (HV) rectifier, and an intermediate secondary storage running in the saturation mode of a time-adjustable HV HF compensatory voltage stabilizer based on a hard-controlled switch, e.g., an electron beam valve or an assembly of HV transistors that provide cutoff of the charging current of the output storage capacitor of the resonant charging circuit of formative lines upon reaching the rated voltage value. The power supply source will have a servo system of charge voltage control and an efficiency of at least 95%. Computerized modeling allows optimizing the design parameters of electrical elements of the power supply source circuit and types of component parts of the circuit’s electrical elements so as to achieve the minimum prime cost and maximum reliability. The best kind of modeling is in EWB and Multisim.

The electric circuit of a modulator at an output voltage up to 10 kV, allowing one to quickly, during a pause between pulses of about 2 ms, to change the pulse duration at a load of 10–30 μs is considered. For the possibility of increasing the pulse amplitude up to 60 kV using a pulsed transformer. At a pulse duration of more than 5 μs is most appropriate to use artificial forming lines based on discrete elements, capacitors and inductors, collected in the form of Γ-shaped LC chains. The pulse duration at the load is changed by changing the number of units of such chains forming a line, collected on a ladder diagram. “Soft” management switches, such as HiPakTM IGBT module switching thyristors, type 5SNA 0400J650100, voltage 6500 V, and a current 400 A, with the lowest possible internal resistance, are used. Computer simulation in the program allows one to optimize previously obtained results of calculation of the forming line assembled from l-shaped LC combinations for the specified load value of about 500 Ω. We performed model optimization of circuit elements and switches. The modeled parameters of components, from the point of view of obtaining a minimum cost and reliability while maintaining the specified electrical characteristics, are given. The EWB and Multisim software are best used.

The human immunodeficiency virus (HIV-1) poses a serious risk to global public health. The development of a safe and effective vaccine could stop the HIV/AIDS pandemic. Much of the research focused on HIV-1 prevention through vaccination is aimed at developing immunogens and immunization strategies to induce the formation of antibodies with neutralizing activity against a broad range of HIV-1 isolates (bNAbs). The objective of this study was to develop immunogens capable of targeting an immune response to MPER, one of the regions of bNAb binding in Env. Two immunogens carrying MPER fragments on their scaffolds (protein YkuJ Bacillus subtilis and artificial polypeptide TBI) were constructed. Circular dichroism spectroscopy was used to show that the secondary structure of the immunogens was consistent with their theoretical models. The antigenic structure of the MPER-TBI and YkuJ-MPER proteins was characterized using bNAbs that recognize HIV-1 MPER (2F5, 4E10, and 10E8). The rabbit model made it possible to show the immunogenicity of the constructed recombinant proteins. The resulting serum was found to be cross-reactive with immunogens carrying MPER. The constructs designed and characterized in this study can be used for targeting the humoral immune response to MPER, which is known to be one of the sites of HIV-1 vulnerability.

The article deals with developing the model of a power supply voltage modulator for the electron-beam gun control electrode within the framework of the project aimed at elaborating scientific and technical fundamentals of controlling the electron beam additive form shaping process. Generally, this technology involves the use of high-power electron beams for sequentially fusing materials in the form of a metal wire. The electron beam electric current is controlled by applying the beam impulse on the fused metal wire. Despite the fact that active efforts are being taken by Russian and foreign companies for developing the technology, clear criteria for choosing the electron beam pulsed modulation parameters have not been determined and depend on the material being processed. The current technical solutions used for energizing the gun’s electron beam and controlling its power are briefly described. The electron beam current pulse modulation system is analyzed with a view to determine the electric voltage modulator optimum parameters and operating modes. A modulator model has been developed and proposed, using which it is possible to evaluate the impulse voltage parameters, to estimate the transients at the front and trailing edges of the modulator output voltage pulses with different duty cycles, and to select the proper components. The electrical circuit of the power supply voltage modulator for the electron-beam gun control electrode was simulated using the NI Multisim 11.0 simulation package.