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This paper concerns a local volatility model in which the volatility takes two possible values, and the specific value depends on whether the underlying price is above or below a given threshold. The model is known, and a number of results have been obtained for it. In particular, option pricing formulas and a power-law behaviour of the implied volatility skew have been established in the case when the threshold is taken at the money. In this paper, we derive an alternative representation of option pricing formulas. In addition, we obtain an approximation of option prices by the corresponding Black–Scholes prices. Using this approximation streamlines obtaining the aforementioned behaviour of the skew. Our approach is based on the natural relationship of the model with skew Brownian motion and consists of the systematic use of the joint distribution of this stochastic process and some of its functionals. [ABSTRACT FROM AUTHOR]

This work implements a method for specific in vivo biotinylation of recombinant proteins M1 and B7 of the variola virus during biosynthesis in CHO-K1 cells. To do this, co-expression of the biotin ligase BirA and target genes encoding the ectodomains of the M1 and B7 proteins with a C-terminal avi-tag was carried out in CHO-K1 cells in the presence of biotin in the culture medium. The optimal biotin concentration for the expression of the M1 and B7 proteins was 125 μM. The production of biotinylated recombinant proteins has been complicated by low yields. To increase the production of target proteins, low molecular weight enhancers were added to the culture medium: lithium acetate, sodium valproate, and caffeine. The enhancers increased the yield of the target protein by 1.3–4.9 times and did not affect the efficiency of biotinylation. The highest yield of biotinylated protein was achieved with the simultaneous addition of a concentration of 10 mM lithium acetate and 2.5 mM sodium valproate. [ABSTRACT FROM AUTHOR]

The cross section for the neutron-induced fission of 237Np nuclei in the neutron energy range of 0.3–500 MeV has been measured using the time-of-flight spectrometer of the GNEIS neutron complex at the Petersburg Nuclear Physics Institute, National Research Center Kurchatov Institute. The 237Np(n, f) fission cross section has been measured with respect to the 235U(n, f) fission cross section and fission fragments have been detected by low-pressure position-sensitive multiwire proportional counters. The data obtained have been compared to the previous experimental results and to estimates from various evaluated data libraries. [ABSTRACT FROM AUTHOR]

This article describes the structure of an intelligent user support service system and research on solving the problem of finding relevant answers to user queries using a neural network of the Transformer architecture, which provides representation of queries in vector form and further search for the closest vectors in a database of frequently asked questions to generate an answer. [ABSTRACT FROM AUTHOR]

Head and neck surgeries require skilled surgeons to avoid facial nerves and blood vessels. Using straight surgical instruments to create a deep and sealed operating environment is difficult. Continuum robots are particularly effective in head and neck surgery due to their extensive range of motion, adaptability, and ability to navigate confined anatomical spaces. This paper presents a new approach to examine the flexibility of the continuum robot in head and neck surgery, motivated by the advantages of continuum robots. This method uses a discretized kinematics model with a constant curvature and a piecewise assumption-fitting-approximation (PFA) method to find closed solutions for the continuum robot's problem. We introduced the concept of spatial solid angle to assess the dexterity of the continuum robot, utilizing the inverse solution of the target point position as a reference. An intuitive dexterity index and dexterity area were proposed. The length of the continuum segment was optimized by simulation, and the efficacy of the approach was then validated through experiments. Experiments demonstrate that the piecewise assumption can cause the dual-section continuum robot to deform as expected. In comparison to previous similar tasks, the robot has exceptional position accuracy, with a position error of only 1.72 % of the overall length. Additionally, it exhibits excellent real-time performance, with a maximum time consumption of 3.9 ms. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of rock magnetic studies and relative paleointensity determinations from sediments of Lake Shira, Khakassia. Carrier minerals of natural remanent magnetization (NRM) were identified through hysteresis loop parameter measurements, thermomagnetic and X-ray diffraction (XRD) analyses. The sediment age was determined by radiocarbon dating; according to age estimates, the studied sediment sequence covers approximately the past 9100 years. To obtain high-quality relative paleointensity results, the determinations were made on linear segments of the pseudo-Arai‒Nagata diagrams. The quality was assessed by the criteria of the number of points in the calculations of slope, quality criterion (q), NRM fraction destroyed in the paleointensity determination interval, and relative paleointensity determination error (σ). According to the rock magnetic studies and XRD analysis, the magnetic carriers are mainly single-domain (SD) and pseudo-single-domain (PSD) magnetite and hematite. The comparison of the obtained relative paleointensity data with model paleointensities calculated for the Shira coordinates from the various models (CALS10K.1b (Korte et al., 2011), PFM9k.1 (Nilsson et al., 2014), HFM.OL1.AL1, CALS10k.2 ARCH10k.1 (Constable et al., 2016)), with absolute paleointensities and with the collection of results from the studies of sedimentary and igneous rocks and archaeomagnetic objects has shown that these data are in good agreement and share common trends. This provides grounds for applying this approach to paleointensity determination from bottom sediments of modern lakes using the pseudo-Thellier method. [ABSTRACT FROM AUTHOR]

MRI is widely used in radiation therapy planning, particularly in stereotactic radiosurgery for brain metastases. The article addresses the geometric distortion of MRI images, which can lead to errors in radiation therapy planning. A series of experiments with a simple phantom were conducted on two MRI scanners with 0.5 and 1.5 T magnetic fields. Deviations in the positions of the phantom objects from their actual locations were observed. The detected deviations can reach up to 5 mm. A theoretical dependence of the magnetic field gradient on the distance to the center of homogeneity was calculated, which agrees well with the approximation of experimental data. An assessment was made of the dependence of the image area distortion of objects located at the center of the field homogeneity on their actual sizes. It was found that the area deviation can reach up to 20 . [ABSTRACT FROM AUTHOR]

We present new results of geochronological, rock magnetic, paleomagnetic and paleointensity studies of the olivine gabbro dyke located at the northern part of the Murmansk craton, NE Fennoscandia (the Kola Peninsula). According to its geochemistry, petrographic and geochronology features, the dyke belongs to the 2.68 Ga dyke swarm, as confirmed by Sm-Nd mineral isochron. We find a significant difference in the rock magnetic and paleomagnetic characteristics of the central and marginal parts of the dyke, which is independently supported by petrography and geochemistry. It is shown that the rocks of the central part of the dyke retained not only their primary mineral composition, but also the primary component of the natural remanent magnetization. We use its direction to determine the 2.68 Ga virtual geomagnetic pole for the Murmansk craton: Slat = 68.64292° N, Slong = 37.7945° E, N = 41 specimens, Plat = –73.5°, Plong = 138.9°, dp/dm = 3.2°/3.4°, paleolat = –65.9°. We also obtain reliable estimates (17 samples) of the Earth's magnetic field intensity at ca. 2.68 Ga: VDM value is found to be 1.85 × 1022 A m2 corresponding to the geomagnetic field several times weaker than the present-day field. [ABSTRACT FROM AUTHOR]

Abstract—A collection of igneous rocks of the Ukrainian Shield sampled from the Korsun-Novomyrhorod pluton (age interval 1760–1735 Ma, Ingul Domain) and from the Korosten pluton (age 1760–1750 Ma, North-Western Domain) is studied. The magnetic and thermomagnetic properties of samples were studied and X-ray diffraction analyses were carried out to obtain reliable determinations of paleointensity (Banc), It is shown that the carriers of the characteristic component of natural remanent magnetization are single- and small pseudo-single-domain magnetite grains. Banc was determined by two methods: through the Thellier‒Coe procedure with pTRM checks and by Wilson method. Paleointensity determinations are obtained from five sites and shown to meet quality criteria. For all sites, Banc and the virtual dipole moment (VDM) values are extremely low, varying within the ranges 3.6–9.76 μT and (0.92–2.43) × 1022 Am2, respectively. The analysis of the data from the paleointensity world database (WDB) indicates that the geodynamo operation mode in the Proterozoic can be characterized by an alternation of strong and weak dipole regimes, but the validity of this conclusion entirely depends on the reliability of data reported in the literature and presented in the WDB. [ABSTRACT FROM AUTHOR]

The planishing of the surface of solids is aimed to minimize its roughness, downgrade a content of larger cracks in the modified layer, and, in general, reduce a thickness of the latter one. However, the abrasive processing induces residual stresses in the surface layer. The stresses relax through the motion of dislocations but in superhard materials like corundum or silicon dioxide, is extremely limited. In the present work, the role of the modified surface layer in corundum was studied within the context of the method and regime choice which affect the surface processing the mechanical characteristics of corundum. An efficiency of the abrasive treatment was assessed by comparison with the properties of surfaces processed with the ion polishing, sheared surface, and natural face of crystal from the viewpoint of reaching the high mechanical damage resistance of the surface. [ABSTRACT FROM AUTHOR]

This study shows the need for a common structured approach to designing control systems for electron-beam welding, surfacing, and additive shaping plants. The main controlled parameters of the process are highlighted. The three-level hierarchical structure of the control system is described. The control processes are differentiated taking into account the process requirements for electron-beam treatment processes and the features of the vacuum system, the electron gun, and the positioning system, as well as the system of taking images of the treated area according to the signal of backscattered electrons. The types and quantitative characteristics of the parameters of the signals necessary for running the system are given. It is shown that it is effective to divide the control processes in three groups, depending on the requirements on the rapid response of the actuators, as well as on the need for synchronizing some processes with others over time. The presented differentiation is used to propose a method for selecting technical facilities for each of the mentioned groups. An example is provided of constructing a control system for an electron-beam process plant using hardware components available for purchase. [ABSTRACT FROM AUTHOR]

Mononuclear nickel complexes [NiL1(NCS)2]·2DMSO (I), [NiL1(NCS)2]·DMF (II), and [NiL2(NCS)2]·0.5CH3OH·1.5H2O (III) with the distorted octahedral coordination node, where L1 and L2 are the tetradentate ligand systems derived from the products of the condensation of diacetyl with 2-hydrazinoquinoline and 2-hydrazino-4,6-dimethylpyrimidine, respectively, are synthesized. The structures of the compounds are determined by IR spectroscopy and XRD (CIF files ССDС nos. 2219793 (I), 2142035 (II), and 2219794 (III)). The quantum chemical modeling of the axial parameter of magnetic anisotropy in the zero field (D) is performed for the synthesized compounds in the framework of the SA-CASSCF+NEVPT2 method. The complexes are shown to be characterized by three-axis magnetic anisotropy close to the light magnetization plane with positive D. The axial parameter of magnetic anisotropy (Dexp = 8.79 cm−1) determined by the approximation of the magnetometry data on complex [NiL2(NCS)2]·0.5CH3OH·1.5H2O is consistent with the calculated value (Dcalc = 11.5 cm−1). [ABSTRACT FROM AUTHOR]

We consider a class of well-known high-order trinomial linear difference equations and analyze the non-asymptotic behavior of their solutions under non-zero initial conditions from the unit box. It is shown that, for certain subsets of coefficients in the stability domain, there always exist initial conditions leading to peak, a large deviation of solutions from the equilibrium position, and that these deviations may take arbitrarily large values. Various special cases are studied, numerical examples are presented. [ABSTRACT FROM AUTHOR]

It is shown that the results of dispersion of various materials in the mode of pulsed current action correspond to theoretical estimates of the wavelength of MHD instability. The sizes of the obtained metal grain, including refractory ones, correspond to the modes of exposure, and their microstructure corresponds to the conditions of formation. Modeling in the Comsol Multiphysics environment at a qualitative level revealed the influence of the thickness of the surface layer of the current flow on the dynamics of the formation and separation of liquid metal droplets. It is shown that one of the operating factors that create and increase instabilities is the heterogeneity of the distribution of Lorentz forces in the current supply zone. [ABSTRACT FROM AUTHOR]

Routes of modification of 5,6,7,8-tetrafluoro-3-methoxycarbonyl-2-(4-methoxyphenyl)-4H-chromen-4-one and its decarboxylated analogs in the reactions with aliphatic amines were studied and the biological activity of both the starting compounds and the products was tested. It was found that 5,6,7,8-tetrafluoro-3-methoxycarbonyl-2-(4-methoxyphenyl)-4H-chromen-4-one under the action of primary amines underwent the flavone-coumarin rearrangement through the addition of the amine at the C(2) atom. 7-Amino-substituted flavones were formed as by-products in the reactions with methyl- and benzylamines and as major products in the reactions with pyrrolidine. The process of nucleophilic aromatic substitution at the C(7) atom becomes a key one in the reactions of decarboxylated tetrafluoroflavones with primary amines and pyrrolidine. Mechanisms for the studied transformations were proposed. The starting tetrafluoroflavones were found to exhibit high antifungal activity, while antigonorrheal agents were revealed among the products of their transformations. [ABSTRACT FROM AUTHOR]

Electrically conductive composite textile and textile combining electrically conductive and magnetic properties have been obtained on the basis of biocompatible non-toxic materials: commercial non-woven textiles, electrically conductive polypyrrole and magnetite (Fe3O4). The composite textile has been formed from two-layer fibers, where the fibers of the original textile are coated with a polypyrrole shell, and the textile combining electrically conductive and magnetic properties have had a three-layer structure, where magnetite particles are deposited on top of the polypyrrole shell. The composite textiles have retained the structure of the original fabric with free interfiber space: the specific surface area of the materials and their mechanical properties have been similar in value. The composition of materials, their electrically conductive, magnetic, and redox properties have been investigated. The interaction of the composite textile and the textile combining electrically conductive and magnetic properties with electromagnetic radiation in the frequency range of 4–8 GHz have been investigated in comparison with a commercial radio-absorbing material based on carbonyl iron. [ABSTRACT FROM AUTHOR]

Squalene-based adjuvant compositions that can provide effective induction of specific humoral immune response have been developed. Recombinant receptor-binding domain (RBD) of surface S-protein of SARS-CoV-2 was used to evaluate the properties of the composition. Immunization of mice with the developed squalene-based compositions in combination with RBD allows obtaining high titers of specific antibodies: from 105 to 2×106. The blood sera from immunized mice exhibit neutralizing activity against SARS-CoV-2 Delta variant (B.1.617.2) with a titer up to 1:2000. [ABSTRACT FROM AUTHOR]

A criterion for estimating the instant of transition from the stage of development of the Richtmyer–Meshkov instability to developed turbulence on rough contact interfaces of layered gas systems is proposed. A number of laboratory experiments are simulated. In the first series of experiments, the Richtmyer–Meshkov instability arises on two contact interfaces of a thin gas layer after passage of a shock wave. In the experiments, a thin layer (corrugated gas curtain) is formed by pumping a heavy gas (SF6) through a nozzle block across an air-filled shock tube. In the second series of experiments, the shock wave passes across the contact interface of two gases of different densities (air-SF6 and He-SF6 layerings) perturbed along a sinusoid. In this series of experiments, the end face of the tube is either connected to the atmosphere or closed by a rigid wall. Development of the Richtmyer–Meshkov instability and transition to turbulent mixing are simulated using the implicit large eddy (ILES) method by means of the MIMOZA technique. A comparison with the available experimental information is made. [ABSTRACT FROM AUTHOR]

The structure is considered for a typical system to control electron beam welding deposition with supplying feed (wire). This approach is used today to implement additive technologies. The main features of the process are described. It is shown that the temperature of the underlying layer changes during surface deposition; therefore, it destabilizes the process through changing the temperature of the melt bath as well as the transverse dimensions of the formed layer. The need to use a feedback control system to stabilize the temperature of the welded layer is substantiated and an approach to its technical implementation is described. The results obtained for a prototype of a temperature stabilizer based on a microcontroller are presented. The fundamental potential is demonstrated to ensure the repeatability of the height of the welded layer and to prevent the wire from detaching the liquid melt bath during welding deposition of a multilayer cylindrical contour made of 316L steel. [ABSTRACT FROM AUTHOR]

Mathematical modeling is applied to study the electrothermal explosion conditions of a gasless system surrounded by a dielectric medium. It is shown how conductive heat exchange intensity and Joule heating power affect the formation of dimensionless temperature and concentration profiles, the integral depth of transformation, and the reaction front propagation velocity. The stages of ignition and reaction propagation are divided using a criterion that assumes a conversion depth of 0.99 at any point in the sample. The amount of product formed at the ignition stage is determined. It is demonstrated that a large transformation depth is achieved near critical conditions during ignition on the axis of the sample, thereby causing the displacement of the ignition zone from the axis to the surface of the sample. [ABSTRACT FROM AUTHOR]

The 243 Am fission cross section was measured for incident neutron energies from 0.3 MeV to 500 MeV on the time-of-flight spectrometer of the neutron complex GNEIS at the NRC "Kurchatov Institute" – PNPI. Fission fragments were registered using position-sensitive low-pressure multiwire counters, which made it possible to simultaneously measure the angular distributions of fission fragments. As a result of processing these distributions, the energy dependence of the angular anisotropy of fission fragments of 243 Am in a wide range of neutron energies was determined for the first time. The cross section of 243 Am(n, f) was measured relative to the 235 U(n, f) cross section. The obtained data are compared with the results of other experimental works. Theoretical estimates for the fission cross section and anisotropy of angular distribution of fission fragments for the 243 Am(n, f) reaction are presented and discussed. [ABSTRACT FROM AUTHOR]

The mechanisms of time-dependent impacts of classical nature (mechanical, magnetic, and electric) on quantum particles, including spin ones, have been theoretically analyzed. It is shown that the considered models allow two parametric mechanisms (Boltzmann and Pauli) for controlling the quantum states of particles. Methods for calculating the time–frequency and amplitude parametric gain regions have been defined and partially implemented for these mechanisms. [ABSTRACT FROM AUTHOR]

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We study properties of the eigenvalues of the Laplace–Beltrami operator on L2 S d N - 1 , restricted to the class of antisymmetric functions. We prove that Vandermonde type determinants generate a basis for the space of antisymmetric homogeneous harmonic polynomials. Based on this fact, we calculate the multiplicity of each eigenvalue for d = 1 and present an algorithm for calculating eigenvalues for d ⩾ 2. [ABSTRACT FROM AUTHOR]

This paper presents algorithms for several "passive" and "active" means of pilot-induced oscillations suppression developed by Moscow Aviation Institute (MAI). By conducting experimental studies using a ground-based simulator, the effectiveness of using these means in suppressing the pilot-induced oscillations is assessed. The integration of "passive" and "active" means is considered. [ABSTRACT FROM AUTHOR]

Titanium nickelide alloys have been prepared by pressure-assisted electrothermal explosion (ETE) synthesis. We have examined the effect of Joule heating power on ETE parameters and the physicomechanical properties of the synthesized alloys. The results demonstrate that raising the electrical voltage applied to the starting mixture leads to a decrease in ignition time and increase in the maximum ETE temperature. The ignition temperature was 350°C, independent of the Joule heating power. X-ray diffraction characterization showed that the major phase in the alloys was NiTi. According to uniaxial compression test results, the compressive strength of the alloys is 1980 MPa. Their microhardness HV is 6.4 ± 0.8 GPa. Instrumental indentation has been used to determine their hardness under load (HM = 9.4 GPa) and characteristics of their plastic and elastic deformation. The synthesized alloys have been shown to have high plasticity. [ABSTRACT FROM AUTHOR]

The combustion of mixtures consisting of titanium powder prepared by SHS hydrogenation and dehydrogenation and black carbon/ boron was studied. It was shown that the oxygen and hydrogen content in Ti powder makes an impact on the combustion characteristics of Ti + C mixtures. It was found that an increase in the hydrogen concentration reduces the combustion temperature, meanwhile, its value is increased with increasing the oxygen content. The mixture with 0.6 wt % hydrogen in synthesized Ti powder did not burn. At 1 wt % oxygen and 0.15 wt % hydrogen, the combustion temperature was showed to reach maximum values, about 3000°C. Contrary to Ti + C mixture, Ti + B mixture components reacted in the SHS mode without additional conditions and the combustion parameters are unaffected by the oxygen and hydrogen content in Ti powder. [ABSTRACT FROM AUTHOR]

The concentration of hydrogen peroxide and hydroxyl radicals in dependence of the intensity (strength) of water drop impact on a solid surface has been measured. The intensity was varied by changing the fall height from 1 to 4 m and the tilt angle of the surface onto which drops fell. It is shown that the content of hydrogen peroxide and hydroxyl radicals in solution increases after the drop impact on the solid surface. Apparently, the main mechanism of the observed effects is the generation of singlet oxygen and its further reduction. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of modern geodynamic movements in bottom structures of the White Sea (Baltic Shield). Based on expeditionary work in the White Sea, data were obtained on the formation of the seabed relief and thickness of unconsolidated sediments under the influence of modern seismotectonic events and geodynamic movements, as well as long-term neotectonic processes. It is shown that the Kandalaksha Bay depression is a modern graben developing along faults activated in the Quaternary. Graben development continues to the northwest, where a new Quaternary structure is being formed. Signs of modern geodynamic movements have been identified. The authors demonstrate the role of disjunctive tectonics in the formation of slopes and tectonic structures transverse to the strike of the bay, morphologically represented by relief ridges cutting the Sredny Ludy rise in Kandalaksha Bay. The influence of modern geodynamic processes on the distribution of thicknesses of Quaternary sediments of various genesis and the mosaic distribution of modern bottom sediments has been established. The influence of gravitational processes involved in the formation of underwater landslides, leading to the appearance of abnormally thick layers of the unconsolidated sedimentary cover, has been studied. [ABSTRACT FROM AUTHOR]

Abstract—Temporal characteristics of the localized damage development initiated by a short-time impact pointed loading of SiC ceramics which is widely applied as a protective material against the shock action upon engineering constructions and people were investigated. The statistics of crack nucleation and relaxation was studied with the methods of acoustic emission and electromagnetic emission, correspondingly. It was shown that the length of intervals between microcrack nucleations follows a power law specific to cooperative phenomena. The time distribution of decaying electric charges which appear on impact-induced crack edges and annihilate after the passage of impact wave was, in contrast, linear. The temporal pattern of the crack relaxation permitted identifying two sets of newly formed damages that are the tiny cracks localized in the grain bulk and those that interconnect grains. [ABSTRACT FROM AUTHOR]

The results of the study of the platinum group minerals of the Baimka gold placer cluster, Western Chukotka, Russia, are presented. Platinum group minerals belong to the iridium–platinum and platinum mineralogical-geochemical types with the Late Jurassic cumulative pyroxenite-gabbro complexes as a probable source. Platinum group minerals came to alluvial gold placers primarily from intermediate reservoirs, which is the Volgian volcanic-sedimentary sequence J3v2–3. Rounded silicate glass inclusions are a specific feature of platinum minerals from the Baimka placer cluster. [ABSTRACT FROM AUTHOR]

Experiments have been performed to investigate the efficiency of the process of thermostabilization of a high-temperature surface with dispersed flow of a heat transfer agent at a pressure of 0.2–0.6 MPa in it and at a mass rate of flow of heat transfer agent of (3.3–6.15)·10–3 kg/s and a surface sprinkler density of 1.67–3.11 kg/(m2·s). Assessments have been made of the amount of heat transfer agent evaporating in all investigated heat transfer regimes. An equation describing various heat transfer regimes has been obtained for heat transfer from a high-temperature surface to a dispersed flow of a heat transfer agent in a criterial form. Criterial equations qualitatively describe experimental data within a small error, which indicates their satisfactory reproducibility in the said range of regime parameters of the process. [ABSTRACT FROM AUTHOR]

A novel class of SARS-CoV-2 main protease (Mpro) inhibitors derived from 1,5,6,7-tetrahydro-4H-indazol-4-ones was designed. Virtual screening based on molecular docking followed by molecular dynamics simulation and MM/GBSA calculations was used for selecting compounds for synthesis and an evaluation. After testing 29 prepared compounds for activity against Mpro, two hits with IC50 values bellow 60 μM were found with the best result of 27.31 μM for racemic amide 9m. SAR and further possibilities for hit optimization were discussed. The effectiveness of different approaches (MM/GBSA and alchemical ABFE) for protein–ligand binding affinity prediction was assessed on the basis of obtained experimental data. The best convergence was achieved when we carried out long molecular dynamics simulations (200 ns) of complexes from docking followed by calculations of free binding energies with MM/GBSA method and explicit accounting of entropy. [ABSTRACT FROM AUTHOR]

A comprehensive methodology for designing a magnetic deflection system for a technological electron gun is proposed. The feasibility of using deflection systems with an internal magnetic circuit and toroidal coil sections to form deflection fields that ensure azimuth beam rotation with a constant angle of deviation from the vertical axis is substantiated. The potential of computer modeling is shown both at the stage of calculating the deflection field and beam displacement and at the stage of creating the design of the system frame for its subsequent manufacture based on 3D printing. The main coil parameters are determined, and the circuit diagram of a current stabilizer with external control from a digital-to-analog converter is developed. Dependences are presented showing the relationship between control signals and deflection angles in the developed unit prototype. It is shown that the proposed technique is universal and can be used to create electron-optical gun elements providing deflection, scanning, parallel transfer or adjustment of technological electron beams. [ABSTRACT FROM AUTHOR]

The method of scanning contact potentiometry (SCP) was investigated in factory conditions, and the functional capabilities of the electrical nondestructive testing (NDT) method to detect structural heterogeneities and technological defects were demonstrated directly in the process of reactor equipment production. [ABSTRACT FROM AUTHOR]

The key points of the main evolutionary line of Articulata, leading from polychaetes to insects, are considered. The far-reaching similarity of the most primitive insects, jumping bristletails, with malacostracans, especially syncarids, leaves no doubt about the origin of the former directly from the latter. The similarity of mayfly nymphs to bristletails indicates that the evolution of Pterygota began with amphibiotic Palaeoptera. Myriapods are secondarily simplified descendants of early hexapods, having lost the division of the body into the thorax and abdomen and other ancestral characters due to transition to a cryptic lifestyle. Entognathous hexapods illustrate the initial stages of myriapodization of bristletails. Following Sharov, insect ancestry can be traced back into deep time via crustaceans to trilobitomorphs, Megacheira, and further to the most ancient arthropods, dinocarids—with grasping antennae but without walking legs! Many structural features of arthropods were formed in Polychaeta—the most primitive Articulata. The group most similar to arthropods are scale worms (Aphroditacea). By analogy with myriapods and entognaths, lobopods and non-arthropodan Ecdysozoa should be interpreted as side branches, which emerged from the dinocarid root of Arthropoda and simplified their body plans. Transformations of body plans occurred through heterochronies and heterotopies (including gamoheterotopies). [ABSTRACT FROM AUTHOR]

For an adequate assessment and effective management of biodiversity and ecosystem services in the vast and extremely heterogeneous territory of Russia, a multilevel approach is required that integrates the tasks of biodiversity conservation on different hierarchical levels (diversity of ecosystems and species) and on different levels of territorial administration. Using the example of the Central Federal District of the Russian Federation, a preliminary methodology for prioritizing territories for biodiversity conservation at three levels of government (federal district, subjects of the Russian Federation, and municipal districts) is considered. To prioritize the territories, the rarity indicators of generalized ecosystem types within these territories and the value of territories for the conservation of "red-listed" animal and plant species are used. It is shown that the high-priority for biodiversity conservation purposes generalized types of ecosystems can be distinguished both on different territorial levels and in different territories within the same level. There is also a contradiction between the management tasks of preserving the diversity of species, requiring spacious habitats and the conservation of rare ecosystems that have a small area. These contradictions can be resolved through the development of environmental strategies for different levels of territorial administration. [ABSTRACT FROM AUTHOR]

The paper describes a high-temperature superconducting magnetic system (HTS SMS) to equip an experimental stand intended for neuron activity researches under constant and low-frequency magnetic fields up to 1 T. The design of the magnetic system together with its electromagnetic and cryogenic parameters is briefly discussed. The test results of the preliminary experiments conducted in liquid nitrogen at 77 K for two interchangeable magnets are given. The first magnet was manufactured in the form of a double pancake coil wound with 4 mm high HTS tape. The second magnet was made of pure copper wire with no frame and was impregnated with a thermally conducting epoxy resin. The advantages of the HTS pancake coil were demonstrated in comparison with the cryo-resistive solenoid. Low energy consumption of the HTS magnetic system will allow conducting continuous non-invasive monitoring of biological objects in a magnetic field. [ABSTRACT FROM AUTHOR]

We present the results of a study on the preparation of dense titanium carbide by SHS compaction. It was found that the use of a mechanically activated reaction mixture of titanium and carbon black powders made it possible to obtain titanium carbide samples with a maximum relative density of 95%. The specific feature of this work is that the mechanical activation of the components of the Ti + C mixtures was carried out in a ball mill for several tens of hours. The influence of the modes of activated mixing on the characteristics of the reaction mixture and combustion parameters was studied. The influence of technological parameters on combustion characteristics and structure of consolidated titanium carbide was also investigated. It was found that the rate and temperature of combustion strongly depend on the size, mass, and density of charge compacts. With an increase in the diameter (20–58 mm) and weight (10–70 g) of pressed samples from mixtures with activated reagents, the combustion rate varied from 10 to 100 cm/s, and the combustion temperature varied from 2200 to 3100°C. A strong influence of the prepressing pressure (applied at the combustion stage) on the combustion rate and temperature was shown: in the pressure range of 0–10 MPa, the combustion rate sharply decreases from 100 to 10 cm/s. In the pressure range of 0–40 MPa, the combustion temperature decreases monotonically from 3000 to 2000°C. A mechanism of high-speed combustion of the reaction mixture of titanium and soot has been proposed, in which the determining factors are the mechanical activation of the components of the mixture (titanium and soot) and the formation of radial cracks (channels) in the pressed samples, which ensure the propagation of incandescent impurity gases into the inner layers and the initiation of the carbidization reaction in the volume of charge compacts. [ABSTRACT FROM AUTHOR]

Phase transformations taking place during synthesis of WC by electrothermal explosion (ETE) were investigated within the following range of process parameters: T = 293–3700 K, 49.8–50.2 at % C, P = 96 MPa, V = 10 V, I = 20 МА/m2, sample diameter of 20 mm. The thermogram of the ETE process was subdivided into four stages (I–IV). Stage I, warmup, temperature range of 293–563 K, endothermic reaction (isothermic plateau), input electric energy Q = 2.96 kJ, specific input energy Е = 111.6 kJ/mol. Low-temperature stage II, 563–1190 K, ignition, Q = 5.46 kJ, Еа = 109.2 kJ/mol. High-temperature stage III, 1190–2695 K, eutectoid decay, order–disorder transformation, Q = 14.25 kJ, Еа = 424 kJ/mol. Stage IV, melting, 2695–3695 K, Q = 14.31 kJ, Еа = 143.2 kJ/mol. The rate of ETE reaction is highly sensitive to applied pressure, concentration of reagents, sample shape, oxide film, etc. Variation in E affords facile control of the ETE process. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental study into the possibility of producing ultrahigh temperature ceramics constituting solid solutions of HfC and ZrC carbides by the single-stage electrothermal explosion (ETE) method under pressure. Adiabatic flame temperature and phase composition of the equilibrium final product were calculated on the basis of thermodynamic data. It was shown that, when the ZrC content in the final product is less than 20 wt %, the adiabatic flame temperature reaches 3800–3900 K, and the combustion product contains hafnium and zirconium carbides. The effect of mechanical activation modes in an AGO-2 planetary centrifugal mill used for a reaction mixture containing Hf, Zr, and C powders on its properties, phase composition formation, and the microstructure of carbide solid solutions was studied. It was shown that high-energy mixing in hexane leads to the destruction of the crystal structure of Hf and Zr particles and the formation of amorphous composite particles. The synthesized samples of ultrahigh temperature ceramics were studied by X-ray diffraction and microstructure analyses. It was shown that exothermic synthesis leads to the formation of single-phase solid solutions of HfC and ZrC carbides with the average particle size of 1.5–0.2 µm. The residual porosity of the binary carbides obtained is 10–12%. It was found that, despite the high temperature of sample heating during ETE under pressure, the particle size of the resulting solid solutions is significantly (by an order of magnitude) smaller than the particle size of similar complex carbides (20–50 µm) obtained by other methods (SPS and hot pressing). This is associated with the rapidity of the exothermic interaction of the reagents (10–50 ms) during ETE. [ABSTRACT FROM AUTHOR]

This paper is concerned with obtaining metal-ceramic composite materials through the method of SHS compaction. The study investigates the influence of mechanical activation of metallic components in reactive mixtures based on the Ti + C + Cr + Ni system on the structure and properties of the resulting composites. Mechanical activation of the Ti, Cr, and Ni metallic powders was performed using two methods. In the first method, Cr and Ni powders were activated separately from the other components of the reactive mixtures using grinding media in a ball mill, after which they were mixed with Ti and carbon black powders. It was shown that the preliminary mechanical activation of the inert components reduces the combustion temperature and rate, which increases the average size of carbide grains. The second method involved a joint processing of Ti + Cr, Ti + Ni, and Ti + Cr + Ni powder mixtures in a ball mill, which were then mixed with carbon black. This method provided mechanical activation of titanium particles while minimizing the impact of grinding media on Cr and Ni powders. This led to an increase in the combustion rate and temperature, a decrease in the average size of carbide grains, and an improvement in the uniformity of the composite structure. A mechanism of interaction between the reagents (Ti + C) involving activated Cr and Ni particles in the combustion and structure formation zones is proposed. According to this mechanism, the mechanical activation of inert components leads to their direct participation in the reaction between titanium and carbon, which determines the reduction in combustion rate and temperature and affects the dispersion and uniformity of the structure of compact composites. The results were used to enhance the uniformity and refine the structure of the STIM-3B composite (synthetic hard tool material grade 3B). [ABSTRACT FROM AUTHOR]

The composition of the lipophilic components of Rhododendron adamsii Rehd. was studied. Acidic and neutral components were identified by gas chromatography-mass spectrometry. Methyl tert-butyl ether (MTBE), which offers all the advantages of diethyl ether but is free of its disadvantages, was used as the extraction solvent for the raw materials. It does not form peroxides or create increased gas pressure due to its higher boiling point. As a result, comparison with databases allowed identification of triterpenic, phenolcarboxylic, and aliphatic acids with chain lengths of 8 to 30 carbon atoms, including saturated, unsaturated, and dibasic acids. More than 150 triterpenic and aliphatic components of the unsaponifiable residue and acidic fractions were identified. Unsaponifiable residues of lipophilic extracts have previously received almost no research attention. Only components of the essential oils of Rh. adamsii and of other species of the genus Rhododendron have been studied in detail. For bioactivity testing, samples of the whole extract and of its fractions were prepared. Some of the studied samples showed inhibitory activity against the main protease of SARS-CoV-2. [ABSTRACT FROM AUTHOR]

The importance of creating hybrid photonic integrated circuits with complex architecture is due to the need for high-performance systems for transmitting and processing large volumes of data. A study is performed of three-dimensional photonic waveguide structures created by direct (3 + 1)D laser printing, with the aim of adding such structures to photonic integrated circuits. [ABSTRACT FROM AUTHOR]

We study the problem of the existence of a coordinate network of curves on a -smooth bordered surface consisting of geodesic lines covering it up to the set of zero Hausdorff measure and lines orthogonal to them. We additionally assume that the surface is symmetric with respect to some geodesic line. Finding this kind of network is reduced to finding a solution to the nonlinear conjugate Beltrami equation in the unit disk, which degenerates at the points at which the Jacobian of the mapping, carried out by the solution, turns to either zero or infinity. The need for this kind of parametrization is associated with the search for equilibrium forms of liquid droplets in a model that takes into account the presence of an intermediate layer when studying the equilibrium state of a two-phase medium. Using the two-fold method of successive approximations, we establish the presence of a mapping of the unit disk to itself satisfying the Beltrami equation. The constructed mapping is continuous on the closed disk. The real part of the map has the generalized first order derivatives square-integrable on the upper half of the disk and the generalized first order derivatives of the imaginary part are locally square-integrable on it, and the map has the Lusin property. The inverse map, defined almost everywhere on the disk, is almost everywhere injective in it and has the Lusin property. The map found defines an almost global semi-geodesic parametrization of the surface and is a natural generalization of the -quasi-conformal maps introduced by R. Finn and J. Serrin. [ABSTRACT FROM AUTHOR]

The mechanical fracture of silicon dioxide initiates the mechanoluminescence (ML) lighting due to multiple breakage of interatomic bonds with producing non-bridged oxygen groups of [≡Si–O–]. The detected ML signals consisted of series of pulses, the energy of which is proportional to the number of photons irradiated from the broken bonds. The comparative analysis of the energy distributions in ML series induced by the impact damage of the surface of crystalline and vitreous SiO2 before and after the Ar+-ion implantation was conducted. The interplay between random and correlated accumulation of broken bonds under the impact loading was found and discussed. [ABSTRACT FROM AUTHOR]

The paper presents parameters of two multi-spectral X-ray detectors based on high resistivity chromiumcompensated gallium arsenide, which convert X-ray signal directly into electrical signal. Detectors consist of 80×80 and 256×256 pixels on 250 and 55 μm pitches, respectively. Their sensitive layer thickness ranges between 500 and 550 μm. At 3–4 keV photon energy, detectors offer high-quality X-ray images in the X-ray radiation range of 10 to 30 keV. Detectors allow distinguishing average densities between 0.3 and 2.4 g/cm3 for 3D printed polymer composites. [ABSTRACT FROM AUTHOR]

Stabilized trimers of the HIV-1 envelope glycoprotein Env are capable of inducing a potent and sustained broadly neutralizing antibody response in laboratory animals and therefore are attractive targets for anti-HIV vaccine development. In this work, a stable producer of the trimer Env recombinant form CRF63_02A6 of HIV-1 was derived from the CHO-K1 cell line. Using immunochemical assays, the trimers synthesized in CHO-K1 cells were shown to be recognized by both monoclonal broadly neutralizing antibodies and sera from HIV-positive patients. The resulting trimers of the recombinant form CRF63_02A6 of HIV-1 can be used both for structural studies and as a candidate vaccine immunogen against HIV-1. [ABSTRACT FROM AUTHOR]