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Purpose of research is to develop and test a technique and perform an experimental study of the vibration strength of D16 aluminum alloy joints welded applying resistance spot welding.Methods. Test coupons were made from 1 mm thick D16 aluminum alloy sheet blanks applying resistance spot welding. A feature of the proposed test is the implementation of a symmetrical loading cycle. During the tests, the number of cycles to failure depending on the range of vibrations was recorded. Annealing and thermomechanical straightening were carried out to exclude helical bending after cutout. After deburring and root facing, the surface of the coupons was prepared for welding using chemical etching. The coupons were welded using a TECNA 8214N spot welding machine. The welding current was 30 kA, the welding duration was 0.1 s, the electrodes force was 180 daN. The static shear strength of the welded joint was studied using a UTS 110M-5 1-U tensile testing machine. The breaking force was 3.66 kN. The peculiarity of the proposed test is the implementation of a symmetrical loading cycle. During the tests, the number of cycles to failure depending on the range of vibrations was recorded.Results. As a result of the statistical analysis of the study results, a linear mathematical relationship between the logarithms of the number of cycles to failure and the amplitude of vibrations was obtained. Depending on the range of vibrations, characteristic zones of destruction were revealed. To provide the possibility of comparing the results of vibration obtained under different conditions of fixing the samples, it is proposed to use the range of vibration displacement per unit length of the work[iece as the ordinate.Conclusion. A technique or studying the vibrational strength of joints welded by resistance spot welding under conditions of a symmetrical loading cycle is proposed and tested. For the studied coupons, the equality of the welded joint to the base metal is achieved at the value of the logarithm of the ratio of the range of vibration displacement per unit length of the coupons equal to 0.01.

We presented a clinical case of the successful treatment of a severe course of polysegmental pneumonia caused by the novel coronavirus infection, that developed in the postoperative period after bariatric surgery in the patient with morbid obesity, comorbid type 2 diabetes mellitus, ischemic heart disease, arterial hypertension, pulmonary embolism (in past medical history), and stage 3 chronic obstructive pulmonary disease. The given clinical case demonstrates the possibility of successful treatment of coronavirus infection in the polymorbid patient at an extremely high risk of an unfavorable outcome, given timely diagnosis, combination therapy using drugs that block cytokine storm, and strict adherence to clinical recommendations.

—The round-the-world Antarctic expedition of the Russian Navy that took place from December 2019 to June 2020 on board the Russian Navy oceanographic research vessel (ORV) Admiral Vladimirsky was supported by the Russian Geographical Society and was dedicated to the 200th anniversary of the discovery of Antarctica and the 250th birthday anniversary of Admiral Ivan Kruzenshtern. One of the expedition’s main objectives was to instrumentally determine the position of the South Magnetic Pole (SMP) whose latest location had been measured more than twenty years before. Planning of magnetometric research, its monitoring and processing of obtained data were carried out by members of the Chair of Geophysical Methods of the Earth’s Crust Study of the MSU Department of Geology and the Fedorov Institute of Applied Geophysics. Based on a set of instrumental determinations (modular proton-precession differential magnetometers, vector three-component flux-gate magnetometers, the ship compass), the SMP position was measured to a precision of ±5 km. Proceeding from the 1980 and 2000 instrumental SMP determinations, it is proven that over the past 40 years, the SMP has been shifting at a consistent velocity in the same direction.

The study area occupies the southwestern part of the Indian Ocean, where the Mozambique and Madagascar ridges are located. Ideas about the tectonic structure of these ridges are still debatable. The anomalous structure of the crust of these ridges can be explained either by underplating — thickening of the oceanic crust from below due to magmatism, or by stretching and thinning of the continental crust. Based on the data on anomalous gravitational and magnetic fields, seismotomography, and other geological and geophysical information, density modeling was performed for four profiles, which revealed differences in the crustal structure and evolution of the Mozambique and Madagascar ridges.

The condensation of 3-formylchromones and 6-amino-5-((3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)amino)-1,3-dimethyl-pyrimidine-2,4(1H,3H)-dione allowed us to synthesize chromone based hybrids containing additional pharmacophores - xanthine and sterically hindered phenol fragments. Novel compounds have been characterized by 1H and 13C NMR spectroscopy, mass spectrometry and elemental analysis. The molecular structure of compound 2 was determined by single crystal X-ray diffraction studies. Compounds 2-9, 11, 12 exhibit cytotoxic activity against human colon carcinoma cells HCT116 and breast carcinoma cells MCF7 at submicromolar concentrations. Compound 11 containing 6,8-dimethylchromone core has the highest cytotoxicity against tumor cells and lowest at non-tumor fibroblasts - this is leader compound of the obtained series with acceptable in vitro selectivity. Synthesized compounds exhibit antioxidant activity comparable to the reference drug Trolox. Combination of promising antioxidant activity and a selective antitumor cytotoxicity in vitro determines the prospects of these compounds as chemotherapy agents.

The impact of mechanochemical activation and methods of addition of non-hydrolyzing salts of NaCl, NH4Cl, NH4Br и MgCl2∙(either dry powder or solution) on the reaction rate and yield of hydrogen production upon magnesium hydride oxidation by water was investigated. It was established that addition of halides increases the hydrogen yield from 22% to 99% (of theoretical value) while the rate of hydrogen production has increased from ∼220 to 1700 mL/min g (MgH2). The addition of dry salts during the mechanochemical treatment of the hydride always results in much higher reaction rate compared to the use of the same salt solutions. It was observed that activation by NH4Cl and MgCl2 results in bell-shaped change in the hydrogen release rate. Of all evaluated halide salt activators, the greatest overall yield (∼99%) was achieved in the presence of 0.17 M NaCl solution. The reaction rate at these conditions was rather slow; it took up to 4 h to complete the oxidation. The highest rate of oxidation, when 94% of theoretical yield was achieved in 3 min, was observed in the presence of 0.85 M NH4Br.

In the present investigation (2002) the current-voltage characteristics (CVCs) of break junctions in polycrystalline $MgB_2$ samples have been studied in the temperature range $4.2 K < T < T_c$. An inelastic Cooper pair tunneling accompanied by the emission of Leggett plasmons has been found for the first time in $MgB_2$ Josephson contacts. A fine structure in the CVCs of $MgB_2$ Andreev point contacts caused by a resonant emission of Leggett plasmons has been observed for the first time. An energy of the Leggett plasmon has been estimated: $E_0$ ~ 4 meV. Distinct two-gap structures have been found in the CVCs of $MgB_2$ tunneling contacts and $MgB_2$ Andreev point contacts with 7.5 meV $< Δ_L, 20 pages (8 pages - preface, 7 pages - electron copy of the "V. Tarasov's Readings" International conference proceedings published in December 2002, 4 pages - electron layout of references and figures), 6 figures. On the occasion of 20th anniversary of the first experimental observation of the Leggett collective plasma oscillation in MgB2

The possibility of constructing a multi-position direction finding system for the case of a priori uncertainty, based on the application of the principles of multiplication of single marks of the location of the emitting target (multistructure principle) and their subsequent partition into classes (clustering principle) is considered. The criteria and algorithms for detecting the resulting cluster and for constructing the optimal estimation of target location stable to anomalous measurement errors are presented, taking into account the time costs of their computer realization. Practical recommendations and results of comparative analysis of different algorithms are given., Automation and Remote Control, Выпуск 4 2023

In 2018, Mishik Airazatovich Kazaryan received the highest award of the International Association for Alternative Energy and Ecology - Order of Antoine de Saint-Exupery “For Improving the Quality of Life on the Planet of People” (IAAEE) on nominating the Award Committee of the Editorial Board of the International Scientific Journal for Alternative Energy and Ecology (ISJAEE). The award was given for his outstanding contribution to development of alternative energetics and ecology. M.A. Kazaryan's prominent contribution to the development of alternative energetics and ecology is based on his pioneering works in the field of development of methods for producing hydrogen as environmentally friendly safe fuel, as well as works in the field of processing organic compounds by various physical methods. As a part of joint research with colleagues from Lebedev Physical Institute of RAS (LPI), M.A. Kazaryan participated in creation of new methods for producing hydrogen from various chemical compounds. The method of conversion of liquid-phase compounds in plasma discharges under the influence of intensive ultrasonic cavitation occupies a special place. In the course of these works, it is shown that low-temperature plasma initiated in liquid-phase media in discharge between electrodes is able to effectively decompose hydrogen-containing molecules of organic compounds and form gaseous products where the part of hydrogen is more than 90%. Estimations of energy efficiency calculated taking into account hydrogen combustion heat and initial substances, as well as electricity costs, showed an efficiency level of about 60–70% in depending on the composition of the starting mixture. Another notable contribution of M.A. Kazaryan to the development of alternative energetics was the work on the optimization and justification of technological and structural parameters of energy discharge devices based on high-voltage pulse-periodic discharge for creating a reactor for plasmachemical processing of polymer wastes into hydrogen and other valuable compounds.

In this work, it was shown that low-temperature plasma initiated in liquid-phase media in the discharge gap between the electrodes is capable of efficiently decomposing hydrogen-containing molecules of various organic compounds and their mixtures with the formation of gaseous products in which the proportion of hydrogen is more than 90% according to gas chromatography data. In the course of work, an experimental setup for hydrogen production was designed and manufactured, which includes a steel reaction chamber with a cooling jacket, a power supply with adjustable parameters, an ultrasonic generator and transducer, and a gas extraction system. Optimal conditions for the production of hydrogen (yield and selectivity) have been found, and principles have been developed for the automation of the process and the design of a semi-continuous pilot plant in order to increase productivity. The reaction products and the purity of the obtained hydrogen are characterized by a set of instrumental methods of physicochemical analysis, including gas and liquid chromatography, microscopy, calorimetry, and other methods. Preliminary estimates of the energy efficiency, calculated taking into account the heat of combustion of hydrogen and the initial substances, as well as the consumption of electricity, showed an efficiency level of about 60–70%, depending on the composition of the initial mixture. Theoretical calculations of the voltage and current of the discharge were also carried out during the simulation of the process, which are consistent with the experimental data. A by-product of hydrogen production by the acoustoplasma discharge method during the decomposition of organic liquids is carbon, which is formed in the form of agglomerates of nanoparticles of various structures and is deposited during the reaction at the bottom of the reaction chamber. As shown by the results of analyzes and stoichiometric calculations, the formation of these by-products consumes most of the carbon and oxygen contained in the molecules of the initial liquid, thereby the resulting gaseous mixture is significantly enriched in hydrogen. The resulting nanoparticles and their agglomerates can also be used as fillers, dyes, components of composite materials.

A series of bis(phenoxy-imine) (FI) titanium(IV) and zirconium(IV) complexes have been synthesized. The effect of the nature of the activator (MAO, combinations EtnAlCl3-n + Bu2Mg and iBu3Al + [Ph3C]+[B(C6F5)4]−) on the catalytic activity and properties of the resulting polymers was studied. It was found that Ti-Fi complexes, despite the nature of the outgoing ligands (Cl or iPrO) in the presence of Al/Mg activators, effectively catalyze the polymerization of ethylene (with the formation of UHMWPE); copolymerization of ethylene with 1-octene (with the formation of ultra-high molecular weight copolymers); and the ternary copolymerization of ethylene, propylene and 5-vinyl-2-norbornene (with the formation of polyolefin elastomers). It has been shown that Zr-FI complexes are not activated by these Al/Mg compositions. The resulting UHMWPE can be processed by a solventless method into high-strength and high-modulus oriented films; however, their mechanical characteristics do not exceed those obtained using MAO.

A series of mono- and polynuclear bis(phenoxy-imine) titanium and zirconium complexes were synthesized. The complexes were immobilized on an MgCl2 carrier prepared by different methods. The homogeneous complexes and supported catalysts were evaluated for ethylene polymerization. The effects of the nuclearity of the precatalysts, nature of organoaluminum activator and the polymerization temperature were examined. It has been shown that immobilized on MgCl2 catalysts are superior in activity to homogeneous precatalysts by the level of activity (up to 6.1 ton of PE (molM h atm)−1). The precatalysts obtained in situ by the interaction of FI complexes, Bu2Mg and Et2AlCl are suitable for preparing ultra-high molecular weight polyethylene (UHMWPE) with molecular weight up to 6 106 Da even at elevated reaction temperatures. In addition, supported precatalysts, in the presence of MAO, effectively catalyze the ethylene–higher olefin copolymerization (activity—up to 8.2 ton of copolymer (molM⋅h⋅atm)−1).

The synthesis of triammonium fulleride (NH4)3C60 by ion exchange of either K3C60 or Rb3C60 with NH4Cl in absolute toluene is reported. According to the Rietveld refinement of a synchrotron radiation-based X-ray diffraction pattern, (NH4)3C60 belongs to the same structure type as both K3C60 and Rb3C60 featuring an fcc lattice with intercalated cations occupying tetrahedral and octahedral cavities of the close-packing formed by fullerene С60 spheres. The ion exchange is incomplete and the final formulation of the product is [(NH4)2.88K0.12]C60. In contrast to earlier suggestions and tabulated ionic radii values, the (NH4)3C60 crystal structure is characterized by a lattice parameter slightly smaller than that of K3C60. A similar reaction between K4C60 and NH4Cl proceeds differently involving the redox step and affords [(NH4)0.48K2.52]C60 again emphasizing the fact that ammonium and potassium in the fulleride phase tend to form substitutional solid solutions. According to low-frequency inductive method, all (NH4)3C60-related phases studied are superconducting with similar temperatures of the superconducting transition around Tc = 16.4 K.

Rapid cytoplasmic streaming in characean algae mediates communications between remote cell regions exposed to uneven irradiance. The metabolites exported from brightly illuminated chloroplasts spread along the internode with the liquid flow and cause transient changes in chlorophyll fluorescence at cell areas that are exposed to dim light or placed shortly in darkness. The largest distance to which the photometabolites can be transported has not yet been determined. Neither is it known if lateral transport has an influence on the induction of chlorophyll fluorescence. In this study, the relations between spatial connectivity of anchored chloroplasts in characean internodes and fluorescence induction curves were examined. Connectivity between remote cell parts was pronounced upon illumination of a cell spot at a distance up to 10 mm from the area of fluorescence measurement, provided the spot was located upstream in the cytoplasmic flow. Spatial interactions between distant cell sites were also manifested in strikingly different slow stages of fluorescence induction caused by narrow- and wide-field illumination. Cytochalasin D, cooling of bath solution, and inactivation of light-dependent envelope transporters were used to disturb cyclosis-mediated spatial interactions. Although fluorescence induction curves induced by narrow- and wide-field illumination differed greatly under control conditions, they became similar after the inhibition of cyclosis with cytochalasin D. The results indicate that cytoplasmic streaming not only drives the lateral translocation of photometabolites but also promotes the export of reducing power from illuminated chloroplasts due to flushing the chloroplast surface and keeping sharp concentration gradients.

Recent discoveries in nonlinear optical properties of nanoparticle colloids make actual the challenge to lower the energy threshold of phase conjugation and move it into the domain of shorter pulse widths. A novel effect of the stimulated Rayleigh-Mie scattering (SRMS) in two-photon absorbing nanocolloids is considered as a promising answer to this challenge. We report the results of experimental and theoretical study of the two-photon-assisted SRMS in Ag and ZnO nanocolloids in the nanosecond-to-picosecond pulse width domain. For 12 ns 0.527 μm laser pulses, the four-wave mixing SRMS scheme provides lasing and amplification of backscattered anti-Stokes signal in Ag nanocolloids in toluene at the threshold 0.2 mJ and the spectral shifts up to 150 MHz. For 100 ps 0.532 μm pulses, we observed for the first time efficient (over 50% in signal-to-pump ratio of pulse energies) SRMS backscattering of the anti-Stokes signal in Ag nanocolloids in toluene and predominantly Stokes signal in ZnO nanocolloids in water, with the spectral shifts up to 0.25 cm−1. We develop the first order-in-perturbation model of the four-wave mixing two-photon absorption-assisted SRMS process which shows that at nanosecond pulses, amplification is predominantly due to the thermal-induced coherent oscillations of polarization while the slow temperature wave acts also as a dynamic spatial grating which provides a self-induced optical cavity inside the interaction region. At a picosecond pulse width, according to our model, the spectral overlap between pump and signal pulses results in formation of only the dynamic spatial temperature grating, and we succeeded at recovering the linear growth of the spectral shift with the pump power near the threshold.

Intercellular communication and transport is the essential prerequisite for the function of multicellular organisms. Simple diffusion as a transport mechanism is often inefficient in sustaining the effective exchange of metabolites, and other active transport mechanisms become involved. In this paper, we use the giant cells of characean algae as a model system to explore the role of advection and diffusion in intercellular transport. Using fluorescent dye as a tracer, we study the kinetics of the permeation of the fluorophore through the plasmodesmata complex in the node of tandem cells and its further distribution across the cell. To explore the role of cytoplasmic streaming and the nodal cell complex in the transport mechanism, we modulate the cytoplasmic streaming using action potential to separate the diffusive permeation from the advective contribution. The results imply that the plasmodesmal transport of fluorescent probe through the central and peripheral cells of the nodal complex is differentially regulated by a physiological signal, the action potential. The passage of the probe through the central cells of the nodal complex ceases transiently after elicitation of the action potential in the internodal cell, whereas the passage through the peripheral cells of the node was retained. A diffusion-advection model is developed to describe the transport kinetics and extract the permeability of the node-internode cell wall from experimental data.

The urgency of the work is due to the depletion of traditional fuel reserves and increasing the load on the biosphere because of emissions from burning coal, oil and gas. The solution of these problems are the development of nuclear energy. The advantages of nuclear energy are analyzed, namely: high calorific value of nuclear fuel, better economic indicators, less environmental pollution. The purpose of this work is to optimize the heat transfer processes in the secondary circuit of a nuclear power plant. It is proposed to take the second circuit of the third power unit of the Rivne nuclear power plant as the object of research. The need for knowledge of heat transfer processes and hydrodynamics is determined by the fact that nuclear reactors are energy-intensive thermal machines, in which these processes are manifested in a rather complex form. Therefore, measures to optimize heat transfer processes in the thermal circuit of the second circuit of the NPP in order to increase energy performance are considered. In order to remove from the system the hardness salts that settle on the walls of the equipment and impair the heat transfer processes, a reagent has been selected to bind the hardness salts. he addition of the PuroTech113 reagent to the working circuit of the secondary circuit made it possible to free the system from the deposition of hardness salts in it, as this reagent "binds" free calcium and magnesium ions. In turn, scale is no longer deposited on the walls of the heat exchange equipment, which allows to fully transferring the required amount of heat. Recalculation of the thermal balance showed that the efficiency of the unit is increased by 3%.The efficiency coefficient of the heat exchanger was chosen as the criterion of optimality. The efficiency of the heat exchanger in the general case is a function of the mode parameters, the scheme of mutual movement of heat carriers and features of hydrodynamics and heat transfer of real heat exchangers. The problem of optimizing the movement of heat carriers in intermediate heat exchangers is solved in paper.

Induction changes in chlorophyll fluorescence are associated with photosynthetic electron transfer, generation of the transmembrane proton gradient, and production of carbohydrates in the CO2 fixation cycle. The reactions of photosynthesis are also accompanied by the outflow of photoproducts from illuminated chloroplasts and their long-distance transport. The exchange of metabolites across the chloroplast envelope membranes is carried out by transporters that are active in the light and cease to operate in darkness. Inactivation of light-dependent envelope transporters in Chara cells interrupts spatial signaling manifested as a transient fluorescence rise in response to illumination of a distant cell area. The dark adaptation was found to down-regulate the entry of metabolites from the streaming cytoplasm into shaded chloroplasts but had rather low influence on metabolite export from illuminated plastids. Fluorescence induction curves were quite sensitive to illumination or darkening of the sample area residing outside the region of photometric assay. The amplitude of slow fluorescence changes observed under dim illumination of the whole Chara internode was substantially larger than under narrow-field illumination of the fluorescence assay region. The results indicate that the slow increase in fluorescence during the induction period in characean cells results not only from photosynthetic activity of chloroplasts in the examined cell region but also from interactions between the analyzed and neighboring cell areas. When the cytoplasmic streaming was arrested by cytochalasin D, similar induction changes were induced by local and global illumination, indicating a disruption of long-range interactions. The results suggest that the liquid flow not only carries metabolites from illuminated to shaded cell parts but also facilitates the export of photometabolites from chloroplasts to the cytoplasm.

In this work, a low-temperature plasma initiated in liquid media between electrodes has been shown to be able to decompose hydrogen containing organic molecules resulting in obtaining gaseous products with volume part of hydrogen higher than 90% as well as nanoparticles of discharge electrodes material. As feedstocks, organic compounds (alcohols, esters) as well as direct water-hydrocarbon emulsions obtained by ultrasonic treatment are used. It is shown that hydrogen productivity from emulsions is not less than that from individual substances. The method of optical spectroscopy was used to confirm the formation of atomic hydrogen in the reactions of plasma decomposition of liquids and to study of plasma characteristics in this process. The measurement of the amount of the gas mixture and nanosized products formed during the decomposition of organic liquids shows that the output is highly dependent on the discharge current, and also on the volume of the discharge, which can vary depending on the distance between the electrodes in the reaction chamber. The dependence of the glow intensity of the discharge on its parameters and materials of the discharge electrodes is shown. In current experiments, the discharge current is from 4A to 8A, the discharge voltage depending on the type of liquid is 30–45 V. It has been found that the simultaneous excitation of an electric arc discharge and acoustic cavitation in water, organic liquids and their mixtures is an effective method for the synthesis of gaseous hydrogen and various types of solid nanoparticles. Ultrasonic action above the cavitation threshold intensifies heat and mass transfer processes in the treated medium, promotes the homogenization of dispersed systems, activation of the surface of solid particles, the appearance of defects in crystal structures due to dislocations and the formation of vacancy complexes, in combination with an electric discharge, which contributes to the appearance of an ionized state of matter (plasma); such an effect is capable of decomposing complex molecules to an atomic state with subsequent recombination and the formation of simple molecules. It has been shown that this is an energetically favorable method for the conversion of liquid-phase compounds, stimulated by thermally nonequilibrium plasma, which produces active particles – excited molecules and radicals, which makes it possible to initiate chain reactions, including energetically branched ones, and thereby significantly accelerate the process of liquid conversion and decrease the temperature allowing for such conversion. Synthesized metal and metal oxide nanoparticles from electrode materials possess activated surface due to the ultrasonic cavitation and can be subsequently used as functional nanoparticles, e.g. nanoparticles with antibacterial properties as well as components of polymer composite materials.

We present experimental data on the synthesis and investigation of the superconducting and structural properties of organometallic fullerides M(3−n)(NR4)(n)C60, where M = K, Rb; R = hydrogen H, deuterium D, methyl Me, ethyl Et, butyl Bu; n = 1, 2, 3, synthesized by exchange reactions of homofullerides of alkali metals of composition K3C60 and Rb3C60 with ammonium halides in the medium of absolute toluene or tetrahydrofuran (THF) at temperatures from 23°C to 110°C. We have studied also superconductivity in Rb2NH4C60 and Rb2ND4C60 samples with replacement of hydrogen for deuterium in ammonium, as well as in K2NH4C60 and K2ND4C60. The superconducting transition temperature did not change with replacement H by D within the measurement accuracy.