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Metal matrix composites based on Fe – Cr – Mn – Mo – N – C system and obtained by the aluminobarothermic variant of self-propagating high-temperature synthesis (SHS) are studied. The possibility of uniform carburizing of a melt obtained by aluminobarothermic synthesis in the cooling crucible is shown. An artificial neural network model is suggested, which makes it possible to predict the carbon content in the studied composite during carburization in the cooling crucible of an SHS reactor (the average approximation error is 9 – 14% depending on the training method). The results of training of the artificial neural network model using the Adam optimization algorithm and the Levenberg–Marquardt method are compared. It is shown that under the conditions of a limited set of initial data, it is effective to use a perceptron with one hidden layer containing three target neurons and one displacement neuron. [ABSTRACT FROM AUTHOR]

The results of high-precision direct determination of CO2 in the surface waters of the Black Sea are presented. These measurements made possible to obtain high precision characteristics of the content and intra-annual variations in pCO2 for the first time. The average annual value of pCO2 is 436 µatm, which is higher than the average annual value in the near-sea surface layer of the atmosphere (420 µatm). The seasonal variability has revealed decrease of pCO2 in seawater from late spring to fall. The minimum values of pCO2 are detected in January–February; the maximum ones, in July. The seasonal variations in the CO2 content in the near-sea atmosphere reveal an inverse relationship, with maximum values in February and minimum values in July. This indicates different mechanisms of the evolution of CO2 in the air and seawater. The content of CO2 in the atmosphere is determined by external sources and depends on the burning intensity of organic carbon. Variations in pCO2 in water is significantly affected by abiotic factors, such as the influence of temperature change on CO2 solubility and the state of the carbon system. In the summer–fall season, pCO2 is determined by a combination of abiotic and biotic factors, including variations in temperature and intensity of biological processes of organic matter transformation. Both the intensity and effect of these factors vary throughout the year, but the abiotic factor remains primay during the entire year. [ABSTRACT FROM AUTHOR]

Assessing the risk of landslides as a result of intense seismic vibrations is an urgent problem in engineering geology. In this article, to assess slope stability, a method is proposed for normalizing the internal deformation of a slope, based on a probabilistic-stochastic approach. The cumulative Newmark displacement is considered as a normalized value, for which empirical relationships have been selected among the accumulated displacement, the level of seismic impact, and the critical acceleration specified by the material parameters of the slope. The method takes into account the uncertainties in the position of possible earthquake sources in the next 50 years in the vicinity of the studied slope, the magnitude of the event(s), and the level of seismic impact. The uncertainties in the physicomechanical parameters of the slope are also taken into account. Normative biases are estimated using reference exceedance probabilities (10 and 5%). The obtained values are compared with the threshold characteristics, and based on this, a decision is made on the slope stability to seismic loads. The value of 10 cm was taken as the lower threshold at which the slope can be considered stable. The technique was successfully tested on a well-studied area of the western slope of Mt. Bolshevik (the south of Sakhalin Island). The balanced estimate of the normative displacement for a 5% exceedance probability was slightly less than 10 cm. The study also provides recommendations for further improvement of the methodology. [ABSTRACT FROM AUTHOR]

The paper presents a computational and theoretical analysis of kinetic processes in methane, nitrogen, and oxygen mixtures for non-self-sustaining direct current discharges supported by an electron beam. Within an approximate approach, the kinetic coefficients in plasma under the simultaneous action of an applied electric field and an electron beam are determined. In a zero-dimensional (spatially homogeneous) approximation, the quasi-stationary composition of charged particles is calculated. The rate constants for generation of chemically active neutral particles of various types in plasma are calculated along with the energy efficiencies (G-factors) of the production of these particles depending on the magnitudes of the reduced electric field and the beam current. Similarity rules are proposed for the relation between the rates of production of active particles under the action of an electric field and an electron beam. It is shown that, by varying the applied field, it is possible to influence the composition of the produced hydrocarbon radicals. [ABSTRACT FROM AUTHOR]

Using a complex of analytical methods, clay minerals were studied in Pleistocene sediments from Hole ODP 1038B (120.50 m deep), drilled on the northwestern edge of the Central Hill (Escanaba Trough, Gorda Ridge) near the hydrothermal source with a temperature of 108°C, as well as in Pleistocene background terrigenous sediments from reference Hole ODP 1037B, drilled in the Escanaba Trough 5 km south of the Central Hill. The terrigenous clay mineral assemblage in sediments from Hole 1037B consists of the mixed-layer smectite-illites, smectite, chlorite, illite, and kaolinite. Sediments from Hole 1038B in the interval from the bottom surface to a depth of 5–7 m are composed of terrigenous clay minerals. In the rest of the sedimentary section, clay minerals are represented by the newly formed biotite, chlorite, and dioctahedral smectite. They were formed during the basaltic melt intrusion into the Escanaba Trough with the formation of a laccolith and the subsequent rapid cooling of its flank. The intrusion was accompanied by the ascent of high-temperature hydrothermal fluid in the central discharge channel, interacting with the adjacent sediments. As a result, the fine-dispersed biotite was formed in sediments at the high-temperature stage of this interaction due to the primary terrigenous clay minerals, K-feldspar, and amphiboles. The rapid cooling of the hydrothermal fluid to a temperature of presumably 270–330°C promoted the partial replacement of biotite by chlorite. The further rapid cooling of the hydrothermal fluid to 200°C and lower and its mixing with seawater seeping into sediments of the Central Hill fostered the formation of smectite. [ABSTRACT FROM AUTHOR]

Recent developments in Deep Learning have opened the possibility for automated segmentation of large and highly detailed CT scan datasets of fossil material. However, previous methodologies have required large amounts of training data to reliably extract complex skeletal structures. Here we present a method for automated Deep Learning segmentation to obtain high-fidelity 3D models of fossils digitally extracted from the surrounding rock, training the model with less than 1%-2% of the total CT dataset. This workflow has the capacity to revolutionise the use of Deep Learning to significantly reduce the processing time of such data and boost the availability of segmented CT-scanned fossil material for future research outputs. Our final Unet segmentation model achieved a validation Dice similarity of 0.96. [ABSTRACT FROM AUTHOR]

We present the results of studying the influence of the geometric shape of the damper on its effectiveness and the overall efficiency of the emission–reception system. One of possible shapes for the damper is considered where it is a truncated cone with the generatrix tilted relative to the piezoelectric plate plane. A criterion for evaluating the efficiency of the damper operation is proposed. The study includes the results of computational-theoretical (using the finite element method) and experimental research on the influence of the tilt angle of the damper generatrix on the signal reflected from its rear part. The generatrix tilt angle at which the minimum of noise signal is achieved is determined. A study of the emission–reception system under load on the aquatic environment is carried out. A satisfactory agreement between the theoretical and experimental results is noted. [ABSTRACT FROM AUTHOR]

Clay minerals were studied in Pleistocene sediments from Hole 1038А (114.50 m deep) and Hole 1038Н (192.80 m deep) drilled near a hydrothermal vent with a temperature of 217°C on Central Hill, 275 m east of Hole 1038B. In sediments from Hole 1038A, at a depth of 8.52 m, <0.001-mm fraction consists completely of chlorite. In the rest of the sediment section in Hole 1038A, clay minerals consist of chlorite (from ~64 to ~98%) and illite. In sediments from Hole 1038H, clay minerals also consist of chlorite and illite. They were formed under conditions related to the intrusion of a basaltic melt as laccolith into the Escanaba Trough and the heating under its influence of a solution, during the interaction of which with sediments at a high-temperature stage biotite was formed. During the subsequent slow cooling of the laccolith and fluid, the newly formed biotite was replaced completely by chlorite. Illite was precipitated from a hydrothermal solution. At a depth of 183 m, in sediments from Hole 1038H, clay minerals consist of biotite, chlorite, and dioctahedral smectite, just as in sediments from Hole 1038B during their formation under conditions of rapid cooling of the laccolith flank and penetration of sea water into the sediments. The paper shows similarities and dissimilarities in the formation of clay minerals in Pleistocene sediments of the Central Hill, located above the slowly cooling part of the laccolith (Holes 1038A and 1038H) and in sediments located above the rapidly cooling laccolith flank (Hole 1038B). [ABSTRACT FROM AUTHOR]

The microstructure of the MgB2 core of the single fiber composite consisting of MgB2, the Nb barrier, and the Cu shell (MgB2/Nb,Cu), which is synthesized by the powder-in-tube method with an ex situ option and by subsequent annealing, has been studied. It is shown that a dislocation microstructure that exhibits high thermal stability is formed in the MgB2 core during cold deformation, in addition to powder compaction. A high dislocation density is observed inside MgB2 grains. Dislocations form walls with low misorientation angles between subgrains. Annealing at a temperature of 900°C for 1 h leads to a higher density of MgB2 ceramics, and the intergranular contact area increases. Moreover, MgO inclusions with a size of 10 nm or less are formed. Thus, various kinds of structural defects are formed, which can be considered as probable pinning centers for the magnetic flux. [ABSTRACT FROM AUTHOR]

The article presents the results of studying changes in the chemical composition of Upper Pleistocene sediments from Hole ODP 1036A drilled in the Middle Valley of the Juan de Fuca oceanic ridge at the Dead Dog hydrothermal field to a depth of 38.50 m, 9 m from a black smoker with a temperature of 268°C. The most significant changes in sediment chemistry occurred in the lower intervals of the hole. In the 20–30.70 m interval, the concentration of a large number of chemical elements increased and, accordingly, the hydrothermal fluid was depleted of these elements. Conversely, in the 30.70–38.5 m interval, the concentration of most chemical elements decreased, which led to significant enrichment of hydrothermal fluid in these elements. [ABSTRACT FROM AUTHOR]

Using the methods of scanning and transmission electron microscopy, the structural-phase states in the transition zone of a layer of fast-cutting S-2-9-2 steel (European standard) surfaced on 14331 medium-carbon steel (CSN standard) is investigated after tempering and electron-beam treatment. As a result of surfacing, a carbide network structure is formed, while there is no network in the transition zone. A plate-like martensitic structure is observed to form in the transition zone. The carbide phase particles measuring up to tens of nanometers demonstrate different morphology in the transition zone. They localize along the grain boundaries of martensitic crystals and austenitic interlayers and on dislocations in the bulk of the martensitic plates. [ABSTRACT FROM AUTHOR]

Abstract—This paper studies the chemical composition stability of modified 1 mol % CaO ceramic composites which contain 50 mol % Al2O3 and 50 mol % [12Ce–TZP] or 50 mol % [3Yb–TZP] and are produced from powders synthesized by a hydrolytic sol-gel method. It is shown that the content of dangerous elements, such as As, Be, Cd, Cr, Pb, and Sb, in the new composites is below the maximum allowable limits. In addition, this paper establishes the high stability in the chemical composition of the composites after a long presence in a media that simulates the conditions of the body. The mass loss for Al is no more than 5 × 10–4 wt %; for Zr, it is no more than 1 × 10–4 wt %. [ABSTRACT FROM AUTHOR]

A multicomponent bulk nanostructured Al20Ti20Fe20Mn20Ni20 high-entropy alloy (HEA) was prepared by the powder metallurgy method. The process involved mechanical alloying of the elemental powders of equal wt% followed by cold compaction and conventional sintering in an inert atmosphere at different temperatures. The structural evaluation and morphological studies of the milled powders were carried out by HRTEM and XRD analysis. The crystal size and d-spacing of the milled powder significantly reduced with the milling duration. The effects of sintering temperatures on the microstructure, wear resistance, and the hardness of Al20Ti20Fe20Mn20Ni20 were investigated. The microstructural analysis showed that the prepared HEAs had a multiphase microstructure consisting of BCC and intermetallic compounds. As the sintering temperature grew, the microhardness and wear resistance increased, demonstrating that the properties of the current HEA were improved by using high sintering temperatures. The increase in density with sintering temperatures and the intermetallic phase contents acted as reinforcement might have enhanced the hardness of the HEA. The best hardness value and the least amount of wear were found in the sample sintered at 900 °C. [ABSTRACT FROM AUTHOR]

The formation of amorphous thin surface layers of nanoporous Ge with various morphologies during the low-energy high-dose implantation by metal ions of different masses, namely 63Cu+, 108Ag+, and 209Bi+, on single-crystal c-Ge substrates was experimentally demonstrated using high-resolution scanning electron microscopy. The structure of the obtained nanoporous Ge layers was studied using backscattered electron diffraction. Under irradiation with low-energy ions, such as 63Cu+ and 108Ag+, needle-like nanostructures constituting a nanoporous thin Ge layer form on the surface of c-Ge. However when employing havier 209Bi+, the implanted layer consists of densely packed nanowires. At high ion-irradiation energies, the morphology of the thin surface layers of nanoporous Ge undergoes a sequential transformation in shape from three-dimensional reticulated to spongy as the mass of the implanted ions increased. Such a spongy structure was formed by sparse individual intertwining nanowires. The general potential mechanisms for pore formation in Ge during low-energy high-dose ion implantation are discussed, including the cluster–vacancy mechanism, local thermal microexplosion, and localized heating accompanied by surface melting with effective sputtering. [ABSTRACT FROM AUTHOR]

Tribooxidation is the main mechanism to adapt the cutting tool to extreme mechanical and thermal loads during high-speed cutting. Wear and tribooxidation processes in the single layer TiAlCrSiYN and multilayer TiAlCrSiYN/TiAlCrN non-stoichiometric coatings on cutting tools after dry cutting with speed of 500 m/min on the running-in and steady wear stages were studied by the set of modern surface analysis methods. The reasonable preference of the multilayer coating comparing to the single layer one was demonstrated. It was established that oxide films with an amorphous-nanocrystalline structure are formed on the surface of the wear hole. Their composition is close to k Cr2O3, TiO2, Al2O3 (sapphire) and Al2O3 · 2(SiO2) (Mullite 1:2). Prospects of yttrium addition in the complex nitride were estimated by quantum chemical calculations, which has shown that such polyvalent metals as Ti+4, Cr+5,6, Y+4, Al+3 in a multicomponent nitride form a very complex spatially organized electronic structure of double and triple bonds with unoccupied π*-orbitals of nitrogen atoms. Quantum-chemical calculations of the oxidation susceptibility of these coatings with Y microadditions confirmed that this element is more inert than chromium and it is predominantly involved in the formation of interatomic bonds with Al, Ti, Cr affecting the mechanical properties of nitride coatings. [ABSTRACT FROM AUTHOR]

Recent publications of foreign and Russian researchers on the influence of niobium microalloying of pearlite steels and high-entropy alloys on their mechanical properties are briefly reviewed. The focus is made on the Nb effect on the microstructure and properties of rail steels and five-component (CoCrFeNiMn) Cantor alloys. The physical mechanisms of strengthening rail steels and high-entropy alloys are revealed and analyzed. An enhanced alloying effect in the case of a combined introduction of Nb + V and Nb + C into the high-entropy alloys is noted and interpreted. [ABSTRACT FROM AUTHOR]

The results of research works on improvement of technical characteristics of high-current photoelectron multiplier tubes manufactured by FSUE VNIIA used in scintillation detectors for studies of pulsed gamma-neutron radiation are given. The design is described and the results of introduction of new technological processes of photomultiplier manufacturing are presented. [ABSTRACT FROM AUTHOR]

The work addresses the issues of controllability of the microarc-oxidation process. This problem is mostly due to the difficulty of analytically characterizing the heterogeneous physical–chemical processes, which are nonlinear and nonstationary, that take place during microarc oxidation. To tackle this issue, a digital twin of the process is being developed, within which an analytical model is proposed to describe the behavior of the equivalent electrical circuit of the galvanic cell during coating deposition. The proposed analytical model of the process is nonlinear and nonstationary, which is attributed to the abrupt decrease in the active resistance of the coating during dielectric breakdowns. Based on experimentally obtained current and voltage oscillograms and the proposed analytical model, parametric identification of the electrical parameters of oxide coatings is performed using the matrix-operator method on the orthonormal Walsh basis. The matrix-operator method is selected because of its applicability to solving problems with both linear and nonlinear equations, as well as stationary and nonstationary parameters and variables, along with the relative simplicity of the mathematical and algorithmic implementation of computations. The calculations result in weight functions of the electrical model of the microarc-oxidation process, reflecting the relationship between the voltage and current in the galvanic cell (coating conductivity). The mean values of the weight functions (average conductivity) decrease during coating deposition, which confirms the adequacy of the proposed model and enables its use for implementing real-time procedures for monitoring coating properties. The scientific novelty of the work lies in the possibility of the real-time control of microarc oxidation through parametric identification of the electrical parameters of coatings using the matrix-operator method. [ABSTRACT FROM AUTHOR]

The effects of atmospheric aerosol, including smoke, on cloudiness are of great interest for understanding the current climate changes. However, the radiative effect of Siberian biomass burning aerosol (SBBA) on clouds in the Arctic has been little studied. Based on simulation with the CHIMERE chemistry transport model and WRF meteorological model, we analyze the processes responsible for origination of the semidirect radiative effect (SDRE) of smoke from Siberian wildfires over snow–ice surfaces in the Arctic, including time- and space-averaged changes in the radiative fluxes, cloud parameters in different cloud levels, and some meteorological characteristics associated with cloud generation due to the radiative effect of (SBBA). The results show that solar radiation scattering by SBBA particles increases the static stability of the atmosphere at altitudes of 2–4 km and suppresses vertical turbulent motions, which decreases the rate of water condensation, the optical thickness of clouds, and the mixing ratio in the medium- and partly lower-level clouds. The decrease in the optical thickness of clouds, in turn, causes origination of positive SDRE of SBBA at the top and bottom of the atmosphere. Radiation absorption by SBBA particles does not play an essential role in these processes, although additionally changes meteorological characteristics. Our results expand fundamental knowledge of aerosol–cloud interactions in the Arctic and can be used for improving climate models. [ABSTRACT FROM AUTHOR]

The studies reported here demonstrate that short probe signals at the output of a narrow-band piezoelectric transducer plate (damperless) mounted on soft tissue can be obtained. Signals of a particular shape are applied to the piezoplate, which allows the duration of the probe pulses to be controlled. [ABSTRACT FROM AUTHOR]

The article presents the results of studying alteration of the hydrothermal solution composition during its percolation in the Pleistocene sediments drilled by ODP Hole 858B (38.6 m deep) in the northern segment of Middle Valley, Juan de Fuca Ridge (Dead Dog hydrothermal field), 20 m away from the hydrothermal source with a temperature 276°C. Influence of sediments in Units I, IIB, and IID from this hole on the solution composition variation during the solution–sediment interaction has been established. The greatest influence on the solution composition occurred during its interaction with sediments of Units IIB and IID under high-temperature conditions (200–350°C) expressed in enrichment of the solution with a large amount of chemical elements. A possible alteration in the solution composition is shown in the process of solution–sediment interaction during its percolation in the sedimentary cover 250–300 m thick. [ABSTRACT FROM AUTHOR]

The preparation of Fe-based wear-resistant coating by high-speed laser cladding method can well solve the problem of poor wear resistance of aluminum alloy surface. However, due to the large expansion coefficient difference of Fe and Al, the Fe-based laser cladding layer on the Al surface often has cracks, poor molding morphology, and poor mechanical properties. In this work, La2O3 is added as an additive in order to improve the morphology and mechanical properties of Fe-based laser cladding layer on the surface of Al alloy. High-speed laser cladding technology was used to prepare the coating of 18Ni300 + XLa2O3(X = 0.5, 1, 1.5, 2 wt %) on ZL205A aluminum alloy. The morphology, microstructure, hardness, wear resistance and heat shock resistance of the cladding layer were studied. The morphology and crack characteristics of the fusion zone were observed by scanning electron microscopy. Under the present test conditions, the addition of La2O3 improved the forming morphology, refined the microstructure of the cladding, and significantly improved the mechanical properties of the cladding. The optimal addition of La2O3 with the best properties was 1.5 wt % which provided: flat cladding surface, absence of internal cracks, refined grain size, improved wear resistance and thermal shock resistance, 47% higher hardness when compared to 18Ni300. [ABSTRACT FROM AUTHOR]

A method is proposed for optimizing the specific flow of a substance at the outlet of filtration membranes with limitations on current, electroosmotic permeability, retention coefficient, and current efficiency at a constant transmembrane pressure. Based on analytical and empirical studies, engineering formulas have been obtained making it possible to calculate the specific output flow for flat-chamber devices with OFAM-K and OPMN-P nanofiltration membranes, which determines the productivity of the electrochemical nanofiltration process of separation of zinc-containing solutions in wide ranges of changes in the electric current density, electrical permeability, and membrane retention coefficient, as well as in transmembrane pressure. The adequacy of the proposed method was verified by comparing calculated and experimental data on the specific flow of matter at the output of the OFAM-K anode membrane and the OPMN-P cathode one. The verification has shown the effectiveness of the obtained engineering formulas in a wide range of changes in the current density on the membranes. [ABSTRACT FROM AUTHOR]

In the present work, a new delivery and dispensing system for root crops is developed. This system prepares the vegetables for subsequent processing. The dependence of the system's energy parameters and the rheological properties of the feed produced on the design parameters is established analytically. [ABSTRACT FROM AUTHOR]

Single-crystal c-Ge plates implanted with Ag+ ions with an energy of E = 30 keV, current density of the ion beam J = 5 μA/cm2 and a dose of D = 2.5 × 1016 ions/cm2 were subjected to rapid thermal annealing by single light pulses of various durations from 1 up to 9.5 s. By scanning electron microscopy and optical reflection spectroscopy measurements it was shown that after ion implantation an amorphous porous Ag:PGe layer of spongy structure, consisting of Ge nanowires, is formed on the surface of c-Ge substrates. It was found that the annealing with an increase in the pulse duration up to 5 s successively leads to an increase in the Ge nanowire diameters from 26 to 35 nm. With longer pulses, the porous Ag:PGe structure is destroyed and Ag evaporates from the implanted layers. [ABSTRACT FROM AUTHOR]

The presence of financial constraints changes traditional auction theory predictions. In the case of multiple items, such constraints may affect revenue equivalence and efficiency of different auction formats. We consider a simple complete information setting with three financially constrained bidders and two items that have different values common to all the bidders. Using a laboratory experiment, we find that, as predicted by theory, it is more beneficial for the seller to sell the higher value item first. We then show that the first-price sealed-bid auction yields higher revenue than the English auction, with significant differences in learning of equilibrium strategies. [ABSTRACT FROM AUTHOR]

The results of measuring the electron temperature and density spatial distributions in plasma of the Globus-M2 tokamak using the Thomson scattering diagnostics are presented. The diagnostics provides measurements throughout the entire tokamak discharge, starting from time of gas breakdown. The Thomson scattering data were analyzed in order to determine the positions of the last closed flux surface, the plasma magnetic axis, and the radius of inversion during the saw-tooth oscillations. The results of measurements performed during the internal reconnection of magnetic field lines are presents, as well as the dynamics of spatial distributions of electron temperature, density and pressure during the plasma transition to the H-mode. The results of measuring the electron temperature distribution in the scrape-off layer using the Thomson scattering diagnostics are also presented for distances up to 4 cm outside the last closed flux surface. [ABSTRACT FROM AUTHOR]

The design of a flat-chamber electrobaromembrane apparatus for separating, concentrating, and purifying solutions and effluents in various industries has been updated. A distinctive feature of the updated design of the apparatus is cooling of the solution for separation in small separation chambers. A method has been developed to calculate the total volume of the solution being separated as well as the total volume of the apparatus body and its components, including the technological and design parameters of the cooling radiator, and to determine the mass of the structural materials for designing and constructing the apparatus. Comparative data showing the effectiveness of the developed design vis-à-vis the prototype is presented. [ABSTRACT FROM AUTHOR]

The GeN experiment aims to search for coherent elastic neutrino-nucleus scattering and to study the other rare processes. The experimental setup is located about 12 m from the center of the 3.1 GWth reactor no. 3 of Kalinin NPP providing the antineutrino flux of (3.6–4.4) × 10 particles cm–2 s–1. The intense antineutrino flux gives a possibility to detect coherent elastic scattering of reactor antineutrinos on Ge nuclei in the regime of full coherence, as well as to study other properties of neutrinos. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the effect of multi-step heat treatment on the formation of the microstructure of the alloy of Al–Mg–Si series, alloyed with scandium and zirconium at the ratio of Mg/Si = 0.3. For this purpose, the base AlMgSi alloy, containing no scandium and zirconium, as well as its modification AlMgSiScZr with additions of these elements were cast. Multi-step heat treatment of AlMgSiScZr alloy consisted of four steps of annealing: at 550°C for 8 h + at 440°C for 8 h + at 500°C for 0.5 h + at 180°C for 5 h. For AlMgSi alloy, it included two steps: at 550°C for 8 h + at 180°C for 5 h. The microstructure of AlMgSiScZr alloy was studied in the cast state, as well as after each step of heat treatment by scanning and transmission electron microscopy, while AlMgSi alloy was studied in the cast state and after the final heat treatment. After each step of heat treatment, the microhardness of the studied alloys was measured. It was found that during cooling of the ingot, in the alloys under consideration coarse intermetallics of Fe2Mg7Si10Al18 type were formed, which partially were dissolved during subsequent heat treatment. At the same time, in the alloy with scandium and zirconium additives, particles that can be attributed either to (AlSi)3ScZr or to the τ (phase) of AlSc2Si2 are present at the intergranular boundaries. No traces of intermittent decomposition of the scandium supersaturated solid solution during cooling of the ingot were found. Heat treatment at 550°C for 8 h + at 440°C for 8 h leads to the appearance of a phase that can be both AlSc2Si2 and Al5SiZr2, while no (AlSi)3ScZr nanoparticles are formed. Heating at 500°C for 30 min enables complete dissolution of the magnesium-containing particles. At the final step, β" (Mg5Si6) particles are formed in the investigated alloys, while scandium has no significant effect on their formation. [ABSTRACT FROM AUTHOR]

The [{Re6Te8}(imzH)6]2+ cationic cluster complex prepared by the interaction of [{Re6Te8} (TeI2)6]I2·[{Re6Te8}(TeI2)4(TeI3)2]·I2 with imidazole (imzH) in a sealed glass ampoule at 200 °C for 48 h. The composition of the obtained compound is confirmed by 1H NMR spectroscopy and high-resolution mass spectrometry. The single crystals suitable for SC-XRD are prepared by slow diffusion of diethyl ether vapors into a solution of the complex in DMF. According to the SC-XRD data, the resulting complex has the composition [{Re6Te8}(imzH)6]I2·2/3DMF. The compound crystallizes in the monoclinic crystal system, P21/c space group, with the following unit cell parameters: a = 18.0379(4) Å, b = 17.9945(5) Å, c = 33.1318(7) Å, β = 115.1829(10)°, V = 9732.0(4) Å3, Z = 6. It is also shown that this compound exhibits solid-state luminescence with an emission maximum at 730 nm characteristic of octahedral rhenium cluster complexes. [ABSTRACT FROM AUTHOR]

Impact tests of low-alloy martensitic-bainitic steel AB2 showed that the scale of dynamic deformation and the fracture mechanism change in a threshold manner. The change in the mechanism and scale of fracture is triggered by the resonant excitation of large-scale structural elements of the material (grain conglomerates) due to plastic flow oscillations. In this case, the grain-boundary mechanism of dynamic fracture is replaced by a transcrystalline one. Beyond the strain rate threshold, mesoscopic elementary carriers of dynamic deformation are divided into two groups: low-velocity and high-velocity. Accordingly, the velocity distribution of mesoparticles shows two humps. The velocity spread of mesoparticles sharply increases under these conditions, while the mass velocity defect (change in the shock wave amplitude) becomes negative. The latter fact indicates the local acceleration of mesoparticles in discrete regions of the target (the so-called shooting of mesoparticles in the shock wave direction). Transcrystalline cracks are randomly distributed throughout the specimen and have a random orientation. [ABSTRACT FROM AUTHOR]

The proposed rotary shredder for root vegetables yields a product meeting the nutritional requirements for animal feed, with minimal energy requirements, because of the low rotor speed and the optimal cutting positions around the drum. The parameters of the shredder are calculated and their influence on its performance is studied. [ABSTRACT FROM AUTHOR]

By the metho ds of modern physical materials science the change in structural-phase state of AlCoCrFeNi high-entropy alloy (HEA) of nonequiatomic composition obtained by the metho ds of wire arc additive technology (WAAM) after irradiation by electron beams with energy density of 10–30 J/cm2, durality of 50 µs, frequency 0.3 s–1 is studied. In the initial state the alloy had a dendritic structure indicating the inhomogeneous distribution of elements. It is shown that electron beam processing forms the structure of high-velocity cellular crystallization with cell size of 100–200 nm, along boundaries of which the nano dimensional (15–30 nm) inclusions of the second phase enriched in Cr and Fe atoms are located. [ABSTRACT FROM AUTHOR]

The scientific and technical literature presents a large number of works dedicated to the experimental study of the critical out flow of saturated and subcooled liquid through cylindrical channels. Despite this, the available sources do not provide an assessment of the extent to which certain geometric parameters and operating conditions of experiments affect the critical outflow. This article is aimed at the analysis of experimental data using statistical methods and machine learning on critical outflow obtained at Elektrogorsk Research and Development Center (EREC, Russia). The purpose of the work is to identify statistical relationships between operating and geometric parameters, as well as to quantify the influence of these parameters on the critical mass flow rate and pressure. The analysis of experimental data for channels with a filleted inlet edge showed a strong influence of the inlet edge shape both on the value of the critical mass velocity and on the final pressure in the outlet section of the channel, which is established at the critical outflow mode. A comparison of the experimental data for channels with different shapes of the inlet section with the same operating and other geometric parameters showed that for channels with a rounded inlet edge, the critical mass velocity is approximately 25% higher than for channels with a sharp inlet edge. As the nozzle throat length increases, this difference decreases asymptotically. Among the regime parameters, the main contribution to the dispersion of the critical mass velocity is made by the undersaturation (subcooling) of the medium at the inlet which comprised 51% of the total influence of the regime and geometric parameters. An increase in the undersaturation and a decrease in the length of the channel throat lead to decrease in the back pressure necessary to establish the critical outflow mode. In extreme cases, the critical pressure ratio (outlet/inlet) can be 0.1, which is significantly lower than the generally accepted value of 0.5 in engineering practice. The results obtained can be used in the future for design of experiments aimed at expanding the range of operating parameters or optimization elements whose operation is based on the phenomenon of critical outflow. [ABSTRACT FROM AUTHOR]

Objectives. To study the general patterns and differences in macroscopic appearances of Broca's speech motor area in the left and right hemispheres of the brain in men and women. Materials and methods. The study was conducted using MRI images of the brains of nine men and nine women (36 hemispheres in total). All men and women were between 20 and 30 years old and had no mental or neurological diseases. The localizations and structures of the main sulci and gyri of Broca's speech motor area, i.e., the triangular and opercular areas, were studied; the topography of the main sulci in Broca's speech motor area, their shape, length, and relationship with other sulci were also analyzed. Results. These studies identified features of the localization of sulci in Broca's area and differences in the numbers of additional sulci in the triangular and opercular areas of Broca's speech motor area in the brains of men and women, as well as the degree of asymmetry of Broca's area in the left and right hemispheres of the brains of men and women. Conclusions. Broca's speech motor area shows differences in macroscopic structure in the brains of men and women. [ABSTRACT FROM AUTHOR]

The morphology of structural components in hot rolled pipes made of 38G2F steel has been studied by optical metallography. It is shown that the sections elongated along the rolling direction with a morphology different from pearlite are sections of upper bainite, the hardness of which is comparable to the hardness of pearlite (~290–300 HVμ). Plotting the thermokinetic diagrams (TKD) of the decomposition of supercooled austenite, as well as a joint analysis of the microstructure and hardness, allowed us to determine the minimum velocity Vcool ~ 0.5°C/s at which the bainite component in the pipe wall is formed. The temperature–time parameters of the decomposition of supercooled austenite with increasing austenitization temperature from 850 to 1000°C have been determined. [ABSTRACT FROM AUTHOR]

An original technique is suggested for pumping a pulsed CO2 laser by a longitudinal discharge in an alternating magnetic field. A small CO2 laser with active medium ∼200 mm long, pulse energy of ∼30 mJ, and efficiency of 3.4% is designed on the basis of this technique. It is revealed that the main factor which limits the generation energy of small lasers is the development of current instabilities in a longitudinal discharge over a cross section of the discharge tube. It is noted that the growth of the instabilities accelerates as the pressure of a CO2 : N2 : H2 : He gas mixture increases to more than 0.1 atm and the specific pump power becomes higher than 3 MW/cm3. The use of an external alternating magnetic field superimposed on a pulsed longitudinal discharge makes it possible to increase the total pressure of the gas mixture in the laser to 0.4 atm when maintaining the combustion of the volume discharge. [ABSTRACT FROM AUTHOR]

Ingots of a composite with a Fe−Cr–Mn–Mo–N–C matrix and reinforcing particles in the form of MgO, Al2O3, and AlN conglomerates have been produced by aluminothermy, which is a version of self-propagating high-temperature synthesis (SHS). The ingots differed mainly in carbon content. It has been found that with an increase in carbon content in the composite from 0.01 to 0.50 wt %, its hardness rises from 238 to 271 HV and its wear resistance improves. The wear resistance has been estimated by abrasive testing under the conditions of dry friction between the sample and a fixed abrasive−electrocorundum Р400 grit (28–40 μm) and Р80 grit (200–250 μm) abrasive paper. As a measure of wear resistance, we chose a decrease in sample weight after tests. The pressure with which the test material acted on the abrasive was roughly equal to 0.25 N/mm2, and the test time was 90 s. The loss in weight was been measured using VLR-200 balance. The hardness has been measured by Vickers hardness testing using an ITV-1-A hardness meter according to State Standard 2999-75 with a holding time of 10 s under a load of 30 kgf. It has been found that a rise in carbon content in the composite causes its embrittlement. It is noteworthy that in passing compressive strength tests samples with 0.01 and 0.16 wt % C remained intact, whereas those with 0.50 wt % C cracked. However, cracked samples continued deforming without complete breakdown up to a load that is maximum permissible for the test machine. The compressive strength has been estimated from the cracking load and has been found to be 3210 MPa. The ultimate compressive strength has been determined using an REM-100-A-2 multipurpose testing machine. [ABSTRACT FROM AUTHOR]

The structures of metal matrix composites based on the Fe – Cr – Mn – Mo system and fabricated by an aluminobarothermal process with the use of argon or nitrogen as the gas atmosphere in the reactor are compared. Chemical analysis for the content of the metals, nitrogen and oxygen in the samples is performed. The structure is studied in different conditions. The total hardness of the samples and the microhardness of their matrixes are determined. It is shown that the morphology of the reinforcing nonmetallic particles depends on the type of the gas atmosphere in the reactor during the synthesis and remains unchanged after a 2-h hold at 1250°C and water cooling. The determined coefficients of recovery of nitrogen from the nitrided chromium and the data of the diffraction analysis are used to show that the aluminobarothermal synthesis under nitrogen pressure is an optimum variant. [ABSTRACT FROM AUTHOR]

A cluster complex of the composition [{Re6Te8}(TeI2)6]I2·[{Re6Te8}(TeI2)4(TeI3)2]·I2 is obtained by a reaction between [{Re6Te8}Te7] and I2 in a sealed quartz ampoule at 400 °C. More than three times increase in the volume of the ampoule in which the reaction is performed with maintaining the other conditions is shown to lead to the formation of the previously described cluster complex [{Re6Te8}(TeI2)6]I2. An increase in the synthesis temperature to 450 °C leads to the formation of X-ray amorphous products of the unknown composition. The [{Re6Te8}(TeI2)6]I2·[{Re6Te8}(TeI2)4(TeI3)2]·I2 compound obtained at 400 °C crystallizes in the triclinic crystal system, space group , and unit cell parameters a = 11.0859(3) Å, b = 11.9021(4) Å, c = 21.1308(7) Å, α = 79.259(2)°, β = 85.533(2)°, γ = 66.220(2)°, V = 2506.55(14) Å3, Z = 1. The crystal structure consists of four layers of two types that alternate along the c parameter: 1) the layer formed by iodine anions and [{Re6Te8}(TeI2)6]2+ cluster cations and 2) the layer formed by neutral cluster complexes [{Re6Te8}(TeI2)4(TeI3)2] and crystallization I2 molecules. Weak interactions between the adjacent cluster complexes are observed in both layers along with I⋯I halogen bonds. The layers are linked with each other via I⋯I and Te⋯I interactions. [ABSTRACT FROM AUTHOR]

Fast-quenched ribbons with thicknesses of 200, 50, 30, and 20 μm have been obtained by melt spinning at hardening disk rotation speeds of 500, 1500, 2500, and 3500 rpm, respectively. The chemical composition of the ribbons has been determined by atomic emission spectroscopy on a Spectroflame Modula S spectrometer. X-ray diffraction patterns of the ribbons have obtained on a DRON-6 diffractometer (CuKα radiation) with a graphite monochromator. The effect of the melt cooling rate on the structural state of the contact and free sides of the Fe77Ni1Si9B13 alloy ribbons has been examined. It has been established that, by increasing the melt cooling rate, one can obtain fast-quenched Fe77Ni1Si9B13 alloy ribbons with different structures: X-ray amorphous at 3500, 2500, and 1500 rpm and crystalline at 500 rpm. Cooling of the melt at a quenching disk rotation speed of 500 rpm makes it possible to obtain Fe77Ni1Si9B13 alloy ribbons with crystallographic structures of three types: A2, C16, and D03 (A2 corresponds to the α-Fe(Si) phase; C16, to the Fe2B phase; and D03, to the Fe3Si phase). In the surface layers on the ribbon free side, texturing of the Fe3Si phase has been detected. It is noted that the crystal structure of the ribbons obtained by melt cooling on a quenching disk at a rotation speed of 500 rpm differs from the structure of the ribbons of this alloy crystallized from the amorphous state by annealing. [ABSTRACT FROM AUTHOR]

The design of a roll-type electric baromembrane purifier for separating, concentrating, and purifying industrial solutions is improved; its parameters are calculated. The relative effective area of separation is doubled. The volume of the separated solution is increased by 38.2% compared to the prototype purifier. [ABSTRACT FROM AUTHOR]

Using aluminium metal matrix nanocomposites has recently gained increased attention in the industry due to their high strength and ductility. In this paper, TiO2 nanoparticles in volume percentages of 5 wt. % were added to the AA2024 alloy using the stir casting method. Using a novel powder injection system, TiO2 nanoparticles with an average particle size of 30 ± 5 nm was added to the matrix. The influence of TiO2 content on the fatigue life before and after heat treatment was studied. The results showed the fatigue properties of AA2024 with TiO2 nanoparticles increased after heat treatment. The optimum improvement in fatigue properties was obtained at 5 wt. % TiO2 after heat treatment, with an improving fatigue life in 14.71% compared with sample based. This is due to an increased number of fine precipitates besides its uniformly distributed after heat treatment. The fatigue life of the composite materials with added nanoparticles was investigated using a finite element-based ANSYS workbench. There was a good match between what happened in the experiments and what happened to the numerical fatigue strength. For the composite materials, the difference between the experimental and numerical values of fatigue strength was not greater than 4% for the matrix. The results also, indicated that, after ageing, the precipitate-free zone at the inter-dendritic zone disappeared or became smaller. However, after adding 5 wt. % of titanium and, also, performing heat treatment, it is not possible to precipitate the Al2CuMg precipitates, and, instead of it, the Al3TiCu and Al7TiCu phases precipitates have been formed. [ABSTRACT FROM AUTHOR]

A new wire-arc additive manufacturing (WAAM) based on Cold Metal Transfer (CMT) welding process is used to fabricate iron-chromium-aluminum (Fe–Cr–Al) alloy by simultaneously feeding two separate wires. A wall of Fe–Cr–Al containing approximately 4.2% Al and 6.5% Cr was deposited over a steel substrate. Chemical composition test performed on the deposited alloy indicated a uniform material distribution of element throughout the deposited wall. It was also found that an increase in Al content or decrease in Cr content improved the hardness of the Fe–Cr–Al alloy. A macro and microstructural characterization revealed that the top region of the wall contained equiaxed grains, whereas columnar grain in the middle region and some acicular precipitates of Fe3AlC0.5 phase at the bottom were observed. The phases at different locations within the built wall were very different, especially, in the top section and bottom section. In the top and middle sections Fe3C carbide were found. The Cr3C2 carbides were found in the top section. No (Cr,Fe)xCy carbides were found at the bottom of the buildup wall. A comparison of bottom and top sections indicated that the (Fe,Cr)xCy carbides have the ability to prevent cracks from occurring. [ABSTRACT FROM AUTHOR]

The process of broadband KrCl laser λrad = 222 nm interaction with nitrogen dioxide in the atmosphere is considered. During the laser pulse, photofragmentation of NO2 occurs, followed by resonant excitation of several electronic vibrational levels of NO A2Ʃ – X2П, ν'ν''(2,2) and NO С2П – X2П, ν'ν''(0,4). The fluorescence intensity of NO A2Σ increases with increasing nitrogen pressure due to intermolecular nonradiative energy transfer from the metastable level of N2 A3Σ to the electronic level of NO A2Σ. [ABSTRACT FROM AUTHOR]

A version of strictly primitive recursive realizability for the language of the basis predicate logic is defined, which takes into account specific features of the language. It is proved that is sound with respect to this version of strictly primitive recursive realizability. [ABSTRACT FROM AUTHOR]

The main mechanisms of flotation activation by ions of metals are discussed and critically analyzed. It is shown that ions of metals can be both activators and depressants of flotation. Based on the mechanism of physisorption, it is revealed when metals act as activators and depressants. A method is proposed to stimulate selectivity of extraction of a target mineral in case of undesirable activation of flotation of associate components. The studies can be useful in selection of metal–activator, ratio of concentrations of activator and collector and pH of flotation system. [ABSTRACT FROM AUTHOR]