Search

Adsorbents based on Silipore 200 silica noncovalently modified with complex compounds of nickel(II) with acetylacetone, benzoylacetone, and ethyl acetoacetate were obtained. The interaction of the vapors of aromatic compounds with the silica surface was studied by gas chromatography: the Henry constants were calculated, the thermodynamic characteristics of adsorption of the class of compounds under study were determined based on chromatographic data, and the contributions of modifying additives to the retention of adsorbates were calculated. The effects of the ligand functional groups in the chelate complex on the differential molar heat of adsorption and the change in the adsorption entropy were studied. The possibility of using the sorbents for gas chromatographic separation of complex mixtures of organic compounds was shown. [ABSTRACT FROM AUTHOR]

The surfaces of solids (gold, silver, and polymers) have been modified with adsorption layers of various compounds. Optimal modification conditions have been determined using the methods of contact angle measuring and quartz crystal microbalance. The degree of surface coverage with the adsorption layer has been calculated and the data obtained have been compared with the results of the direct measurements of adsorption. The surface energy of the modifying layers has been determined and the potential application fields of the modified solids as functional materials have been demonstrated. [ABSTRACT FROM AUTHOR]

The self-gravitating Higgs field of a scalar charge is studied in the case of an asymmetric scalar doublet containing not only the canonical but also a phantom component. We show that in the zeroth and first approximation in the smallness of the canonical and phantom scalar charges, the gravitational field of the scalar charge is described by the Schwarzschild–de Sitter metric with a cosmological constant determined by a stable equilibrium point — the vacuum potential of the canonical Higgs field and the zero value of the scalar potential. An equation for the perturbation of the stable value of the potential is obtained and studied, and the asymptotic behavior in the near and far zones is found. The averaging of microscopic oscillations of the scalar field is carried out and it is shown that the sign of the contribution of microscopic oscillations to the macroscopic energy of the scalar field is completely determined by the values of the fundamental constants of the Higgs potential of the asymmetric scalar doublet. Particular attention is paid to the case where the contribution of oscillations to the macroscopic energy and pressure densities is strictly equal to zero. Possible applications of the obtained solutions are discussed. [ABSTRACT FROM AUTHOR]

Actinobacteria cells Rhodococcus erythropolis 4-1 and Rhodococcus erythropolis 11-2 and Proteobacteria Alcaligenes faecalis 2, which have amidase activity, were immobilized by entrapping barium alginate and agarose into the gel structure, as well as by obtaining biofilms on thermally expanded graphite (TEG). The operational stability of such immobilized biocatalysts after storage in frozen and dehydrated form was determined, and a prototype of a conductometric acrylamide biosensor based on such a bioselective agent was developed. The most preferred method for storing immobilized cells was freezing at temperatures from –20 to –80°C; long-term storage is also possible wet at 4–25°C. It was shown that these cells were most preferable for the biodetection of acrylamide A. faecalis 2, immobilized in an agarose gel structure. An agarose gel with bacterial cells immobilized in its structure had greater mechanical strength and stability during successive cycles of conversion of acrylamide into acrylic acid compared to barium alginate gel. The mechanical strength of barium alginate gel can be enhanced by the addition of carbon nanomaterials during cell immobilization. Growing biofilms on carbon materials used for manufacturing electrodes is also promising. Biofilms of R. erythropolis 11-2 on TEG are capable of converting acrylamide into acrylic acid in more than 20 reaction cycles while maintaining at least 50% amidase activity. [ABSTRACT FROM AUTHOR]

The spatially distributed ECOMAG runoff formation model was used to calculate physically based changes in the water regime in the Ural River basin in the XXI century with the use of data of an ensemble of Earth system models and scenarios of anthropogenic impact on the climate system, leading to a considerable decrease in the uncertainty of the existing estimates of the future runoff of the Ural River. Water management calculations for the Ural River were made with the use of the VOLPOW simulation model, which implements the solution of water balance equation by time intervals. The results of variations of the annual and seasonal runoff of the Ural River at different sections were obtained taking into account the effect of the Iriklinskaya Hydropower Station and the Sakmara River under scenarios RCP 4.5 and RCP 8.5 in the nearest future and in the late XXI century. The current potential of runoff regulation in the Ural River by reservoirs was evaluated, and variants of reservoir operation curves for the optimal use of the available water resources are presented. Variants are proposed for adaptation of the rules of runoff regulation by the Iriklinskoe Reservoir and its operation characteristics under expected climate changes in the XXI century, based on water management calculations with the use of long-term series of daily water inflow, determined by the ECOMAG model under scenarios RCP 4.5 and RCP 8.5 relative to the base period 1976–2005. [ABSTRACT FROM AUTHOR]

TS-13 (sodium 3-(3'-tert-butyl-4'-hydroxyphenyl)propyl thiosulfonate) is a synthetic antioxidant that in numerous studies has demonstrated biological effectiveness in modeling pathological conditions in vivo, in particular, in the model of Parkinson's disease. To establish whether these effects are indirect or associated with, among other things, the direct effect of TS-13 on the organs and tissues of animals, in this work we determined the concentration of TS-13 in the blood plasma and brain of rats after intragastric administration. After a single intragastric injection of TS-13 solution at a dose of 100 mg/kg to male Sprague Dawley rats (n = 57), biomaterial (blood, brain) was collected over 24 h. To measure the concentration of a substance in samples, a bioanalytical technique using high-performance liquid chromatography with UV detection was developed and validated. The quantitative determination method was developed by us for the first time and validated before the study. It has been established that the calculated values of the calibration samples meet the acceptance criteria (have the required accuracy and precision) in the concentration range from 0.05 to 6 μg/mL, R = 0.9998. The results of determining the concentration of TS-13 in the blood plasma and brain of rats showed that after a single oral administration the compound enters the blood, where it is detected within 15 h (average retention time 7.94 h, half-life 7.59 h, elimination constant 0.13 h–1, total clearance 40.1 L/(kg h)), and also penetrates the blood–brain barrier, quickly entering the brain (maximum concentration is achieved after 1 h). The compound has low affinity for brain tissue (tissue availability 0.32), and, therefore, its concentration does not reach high values; however, slow elimination of the substance is observed—average retention time 6.56 h, half-life 6.43 h, elimination constant 0.11 h–1. After a single intragastric administration to rats, TS-13 enters the blood, where at least part of it is detected unchanged after 30 min, reaching maximum values after 1 h. A similar kinetics of the substance is characteristic of the brain, where it is found in smaller quantities. Thus, as a result of the study, it was shown that TS-13 penetrates the blood–brain barrier and is able to directly affect brain structures, which, however, does not negate the possibility of an indirect effect, mediated by the ability to change the activity of intra- and intercellular signaling systems. [ABSTRACT FROM AUTHOR]

This article discusses the features of using elastic bush–pin couplings. Calculation and selection of fits is presented for the case of using elastic bush–pin coupling halves of different designs with different diameters of landing holes. The connection between the shaft of an A280S8 electric motor and the shaft of the WVP'1-25 vacuum pump with an elastic sleeve-pin coupling was chosen as the object of research. It has been found that the electric motor shaft connection with a 80 mm coupling during assembly using the pressing-in method should be assigned an H8/t6 fit, and when heating the coupling, H8/t7. To connect the shaft of WVP'1-25 vacuum pump with a coupling of 65 mm, for any type of assembly, one can assign an H8/t6 fit, in which the maximum tension is four microns higher than the maximum established limit of technological tension, which can lead to destruction of the cast iron coupling. In this regard, it is recommended to the coupling manufacturer to increase the equipment accuracy in order to provide a fit for the connection of the vacuum pump WVP'1-25 shaft with a coupling of 65 mm in the form of H7/t6, which will meet the calculated accuracy requirements. [ABSTRACT FROM AUTHOR]

The authors studied the possibility of using the wire arc additive manufacturing (WAAM) technology for creating blanks by gradually depositing layers of three grades of stainless steel using a wire. Metallographic studies, ferromagnetic analysis, tensile and fatigue tests were carried out. It has been established that the chemical composition of the utilized grades of stainless steel has a significant effect on the morphology and degree of development of dendrites formed during the deposition process. The absence of incomplete fusion and other technological defects at the weld bead interface promoted the possibility of using WAAM to create biand tri-metal deposits. The analysis of the fracture surfaces of the samples confirmed the high quality of fusion of various grades of austenitic steels with each other and the uniformity of the deposited metal. The presence of ferromagnetic phases in the samples immediately after the additive process is significantly lower than the calculated values for steel 07Cr25Ni13 and practically reaches the values that are characteristic for this steel after heat treatment. [ABSTRACT FROM AUTHOR]

The fracture strength and dislocational structure of hard alloys and the wear resistance of wear-resistant nanostructured coatings are studied. The strength of structural elements in the alloys is assessed. Recommendations are made regarding the selection of the hard alloy and nanostructured coating for high-speed machining. [ABSTRACT FROM AUTHOR]

The fabrication of ternary Cu–Mn–Al alloys through self-propagating high-temperature synthesis and their thermoelectric properties, such as electrical resistivity and the Seebeck coefficient in a wide range of temperatures, were studied. XRD analysis identified the Heusler compound Cu2MnAl in the synthesized compositions as a main precipitated phase. In addition, different secondary phases (Al2Cu, Cu3Al AlCu, and Mn) appear depending on an excess of aluminum or manganese in the green mixture. The magnetization (M–H) curves constructed for the studied alloys showed their weakly ferromagnetic behavior. [ABSTRACT FROM AUTHOR]

The article presents the results of studies subject to establish the dependencies of thermal, mechanical and technological properties of highly filled polyphenylene sulfides depending on the mineral fillers introduced into the glass-filled polyphenylene sulfide. Mineral fillers differed in chemical and physical structure and nature. It is shown that the filling of glass-filled polyphenylene sulfide with powdered fillers does not affect the level of electrophysical properties, but significantly affects the physical, mechanical and technological characteristics of highly filled materials. [ABSTRACT FROM AUTHOR]

Among the seven-membered ketals of pyridoxine containing hydroxymethyl groups in various positions of the pyridine ring, an unusual ability of selenium dioxide to catalyze the reaction of nucleophilic substitution of the hydroxyl group by N,O-nucleophiles was found. Quantum chemical calculations have shown the possibility of the formation of selenium dioxide adducts with substrates and the formation of reactive intermediates—ortho- and para-pyridinone methides. The antioxidant and antimycotic activity of the obtained compounds was determined. [ABSTRACT FROM AUTHOR]

The review considers new quaternary ammonium compounds based on pyridoxine derivatives, which were obtained and studied in 2013–2023 at the Research and Educational Center for Pharmacy of the Kazan (Volga Region) Federal University. Four structurally related classes of compounds are discussed, including mono- and bis-ammonium derivatives of pyridoxine, pyridoxine derivatives with cleavable linkers bearing an ammonium moiety, and ammonium derivatives of the unnatural pyridoxine mimetic, 3-hydroxypyridine. Synthetic schemes, biological properties, and key structure–activity relationships of the target structural series are described. For the lead-compounds belonging to specific structural chemotypes, a comprehensive profile of pharmacological properties is described, including antibacterial activity against a wide panel of Gram-positive and Gram-negative bacterial strains including clinical isolates; in vitro and in vivo toxicity; influence on the development of drug resistance. The mechanisms of action of the considered compounds as well as the prospects for their practical use are discussed. [ABSTRACT FROM AUTHOR]

Archive data (1970–2024) on the results of monitoring the tritium content of surface liquid radioactive waste (LRW) storage reservoirs (special radioactive waste repositories) and of groundwater in the vicinity of the Mayak Production Association are analyzed. The tritium contamination existing today was formed before the 1970s and was initially accumulated (a) in V-2 reservoir (Kyzyl-Tash), which operated as a reservoir for recirculating direct-cooling of industrial uranium–graphite reactors (PUGRs) in case of failure of uranium slug cladding; (b) in V-9 (Karachay) and V-17 (Staroye Boloto) reservoirs, which were used for storage of intermediate-level tritium-containing liquid waste; (c) in groundwater as a result of tritium seepage from the reservoirs. After putting into operation the RT-1 radiochemical plant (1977), the major fraction of tritium was accumulated in a new LRW type, tritium condensate, which was stored in V-17 reservoir. The contaminated groundwater filtering from V-17 reservoir was discharged only into an inlet of V-10 reservoir of the Techa Cascade of Reservoirs (TCR). The maximal rate of tritium discharge was estimated at 0.11 TBq/year, and the specific activity of tritium in the TCR water, at 2 Bq/L. In the 2020s, the tritium discharge into the atmosphere from the RT-1 plant was ~34 TBq, which was ~2800 times lower than the maximum permissible discharge prescribed for the whole enterprise. The mean value of the annual effective dose from all the pathways of tritium intake by Ozyorsk inhabitants was 0.26 μSv, and the maximal value was 0.49 μSv, which is ~2000 times lower than the dose limit of 1 mSv for the population. The tritium emissions and discharges from the RT-1 plant are negligible and exert virtually no radiation impact on the population. [ABSTRACT FROM AUTHOR]

A numerical scheme of new class is presented for computing unsteady swirling flows in nozzles and pipes based on equations for a compressible inviscid gas. The main advantage of such schemes is that they are efficient as applied to unsteady multiscale problems. A scheme of this type is constructed using Godunov's well-known approach, according to which fluxes on faces of mesh cells (volumes) are computed by solving auxiliary one-dimensional problems near each face and by approximating conservation laws. An analysis of the current solution near the face is used to switch between explicit and implicit flux computation algorithms. The scheme is unconditionally stable, and it does not generate spurious oscillations. The performance of the scheme is demonstrated by computing unsteady swirling flows in nozzles and pipes. The features of the formulation of problems of this type are investigated, and variants of correct problem formulation are proposed. The properties of solutions of the swirling flow problem with a central body covering part of the axis of symmetry in the computational domain are studied. [ABSTRACT FROM AUTHOR]

We studied the influence of metabolites of permafrost microorganisms obtained at different temperature incubation conditions on activity of differentiation of regulatory (Treg) and effector T lymphocytes. It was found that the effect of metabolites is largely regulated by their type that depends on the temperature of production ("cold" at 5°C, "medium temperature" at 22°C, and "warm" at 37°C). The studied metabolites influenced the differentiation of Tregs (CD4+CD25hiCD127—) and the expression of markers of early (CD69), middle (CD25), and late (HLA DR) activation of CD4+ and CD8+ T lymphocytes. In the case of "cold" metabolites, the increase in Treg levels was associated with a decrease in the intensity of CD4+ T lymphocyte differentiation, and under the influence of "warm" metabolites — with a decrease in the activity of CD8+ T lymphocyte differentiation. Under the influence of "medium-temperature" metabolites, Tregs had approximately the same effect on the intensity of CD4+ and CD8+ T lymphocyte differentiation. [ABSTRACT FROM AUTHOR]

Gold(III) compounds with tetrakis(4-tert-butylphenyl)porphyrin, [Au(TTBPP)][AuCl4] (I), and with tetrakis(4-isopropylphenyl)porphyrin, [Au(TIPPP)][AuCl4] (II), were synthesized for the first time. The obtained compounds were characterized by elemental analysis, 1H NMR spectroscopy, cyclic voltammetry, and X-ray diffraction analysis of solvated complexes (CCDC no. 2333206 (Ia) and 2333207 (IIa)). Study of the structures of the obtained gold(III) complexes confirmed their specific character consisting in the formation of additional Au⋯Au and Au⋯Cl contacts between neighboring complexes giving weak intermolecular bonds. [ABSTRACT FROM AUTHOR]

This article presents the systematic data on the effects of carbon and boron on the microstructure and phase elemental composition of the hybrid multi-component alloys, containing (wt pct) 5W–5Mo–5V–10Cr–2.5Ti–1Mn–1Si–Fe(balance). The nominal concentrations of boron were 1.5, 2.5 and 3.5 wt pct; at each boron level, the carbon content was 0.3, 0.7 and 1.1 wt pct. The following phases were identified in the alloys: (a) (W,Mo,V)-based borocarbide M2(B,C)5 (primary particles and eutectic fibers), (b) Ti-rich carboboride M(C,B) (primary dispersions); (c) (Cr,Fe)-rich carboboride M7(C,B)3 (eutectic lamellae); (d) boroncementite M3(C,B) (eutectic plates); (e) matrix. Boron was responsible for the M2(B,C)5 formation while the M(C,B) was controlled by carbon. Boron and carbon change the eutectic carboboride type as follows: M2(B,C)5 → M7(C,B)3 → M3(C,B). Furthermore, B and C deplete the matrix by chromium enabling the pearlite/martensite structure instead of ferrite. A microstructural map is proposed to select the composition for a specific wear condition. [ABSTRACT FROM AUTHOR]

Solutions in acetonitrile of three mixed complexes of rare-earth elements (terbium and samarium) with organic ligands with various pyridine substituents were studied in this work. The ratios of ligands and metals in the resulting complexes were determined, and the stability constants of samarium complexes were calculated using the spectrophotometric titration method. Measurements of absorption-, emission-, and excitation spectra of luminescence, luminescence kinetics of solutions of mixed complexes of rare-earth elements with an excess of metal relative to the ligand were carried out at various temperatures in the range 298–328 K. For the first time, an increase of luminescence intensity of a samarium ion in complex upon heating was observed. The dependences of the luminescence quantum yield and lifetime of mixed complexes on temperature were obtained. A thermometric parameter—the ratio of the integral luminescence intensities of samarium and terbium ions—was proposed, and the temperature sensitivity coefficient of this parameter was determined for different complexes. [ABSTRACT FROM AUTHOR]

The sealing cup selection procedure for shaft surfaces during repairs is substantiated theoretically and tested practically. The procedure consists of justifying the diameters of the repair dimensions of the shafts based on wear data and selecting sealing cups for these dimensions according to the internal diameter in order to ensure the same tightness as for new connections. The practical application of the procedure is considered on a transmission output shaft connection. [ABSTRACT FROM AUTHOR]

The chemical structure of organic matter (OM) pools in the 2–1-mm water-stable macroaggregates isolated from air-dry aggregates of the same size in arable horizons of noneroded, eroded, and depositional agrochernozems was studied with solid-state 13C-NMR spectroscopy. The changes in their chemical structure in the denudation–accumulative landscape are assessed. The overwhelming majority of water-stable macroaggregates in the erosional zone are newly formed due to dynamic replacement of OM in situ, which is clearly demonstrated by the integral chemical structure indicators in all OM pools in macroaggregates. Analytical data suggest the prevalent transport of newly formed macroaggregates. The destruction of macroaggregates during the transport phase is accompanied by the release of previously physically protected aggregated OM, which undergoes partial mineralization. Note that its most labile (hydrolyzable) part is predominately mineralized, whereas its stable part remains weakly changed or intact. Mineral-associated OM (clay and residue) weakly changes or does not change at all, retaining relative freshness, which indirectly suggests the prevalent migration of newly formed macroaggregates from the erosional zone. A greater degree of freshness of LFfr (free OM) in macroaggregates of depositional agrochernozem results from the abundance of fresh crop residues of the depositional zone together with the residues transported from the erosional zone. [ABSTRACT FROM AUTHOR]

The construction and operation of nuclear power plants are characterized by significant capital costs associated with ensuring compliance with stringent nuclear safety requirements. To ensure a low estimated cost of electricity generated at nuclear power plants, it is especially important to increase their efficiency, which depends on the thermal efficiency of the turbine unit. Based on the criterion of economic efficiency, directions for increasing the thermal efficiency of nuclear power plants with pressurized water reactors (PWR) have been studied: increasing the fresh steam pressure, reducing the steam pressure in the condenser, optimizing the structure and parameters of the second circuit, and improving the efficiency of the turbine flow parts. Significant economic losses are caused by the use of a circulating technical water-supply system provided for at all designed nuclear power plants (according to Article 60 of the Water Code of the Russian Federation). It is noted that the ban on the use of direct-flow water supply systems contradicts the world experience of creating nuclear power plants. The difference in the efficiency of cooling systems of two types is clearly shown by the example of the design indicators of the Leningrad NPP-2 (LNPP-2) and the Tianwan NPP (power unit nos. 7, 8), which use identical reactor systems (RS) but different turbine units and technical water supply systems, which determines the difference in electrical power (up to 66 MW). Using data from the PRIS (power reactor information system) information system on power reactors around the world and the results of calculations by turbine construction companies, the level of thermal efficiency of low-speed turbines abroad, achieved through comprehensive optimization of technical solutions, was assessed. The reserves for increasing the economic efficiency of domestic nuclear power plants with PWR have been identified. It was noted that foreign companies do not stop working to improve the performance of the flow part of low-speed turbine units: models have been created with a last-stage blade length of 1905 mm. According to estimates, the total economic effect from increasing the efficiency of nuclear power plants when implementing all of the above measures, expressed through allowable additional investments, is 14 billion rubles, which is comparable to the cost of supplying all the key equipment of the power unit's turbine room. [ABSTRACT FROM AUTHOR]

The mechanical properties of 10Kh12N10Т and 08Kh18N9 stainless steel components in additive manufacturing are investigated. Selective laser melting (SLM) and wire arc additive manufacturing (WAAM) are considered. Components produced by selective laser melting are found to be stronger than those produced by wire arc additive manufacturing. Additional heat treatment reduces the strength but improves the plasticity, especially in wire arc additive manufacturing. The influence of structural porosity on the mechanical properties of the components is assessed. [ABSTRACT FROM AUTHOR]

A systematic study has been performed for the effect of nonionic surfactants (NSs), i.e., ethoxylated higher fatty alcohols with different ethoxylation degrees, on the ultrasonic dispersion of carbon nanotubes in aqueous solutions and on the colloid-chemical properties of the resulting dispersions, namely, their optical density and the sizes and electrokinetic potentials of the particles in the colloidal systems. A non-linear dependence of the characteristics of dispersions on the ethoxylation degree has been revealed. This dependence is associated with structural transformations in NS molecules. The most efficient ethoxylation degree and concentration of nonionic surfactants in a solution, which have the highest disaggregating and stabilizing effects upon the preparation of carbon nanotube (CNT) dispersions, have been determined. The influence of the ethoxylation degree of the ethoxylated higher fatty alcohols on the electrokinetic properties of CNT dispersions has been revealed. It has been shown that carbon nanotube dispersions can be used to modify the rheological and electrical properties of gel systems based on rarely crosslinked poly(acrylic acid). The effects of NSs and CNTs on the viscosity, shear yield stress, consistency index, mechanical stability, relaxation time, and viscous flow activation energy of the polymer gels have been studied. It has been shown that the incorporation of nanotubes increases the electrical conductivity of the gels. The ultrastructure of the gel samples has been studied by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

The 4π methods used to measure total reaction cross sections σR are presented; they are based on the detection of prompt γ rays and neutrons by scintillation spectrometers with a solid angle Ω close to 4π. The experimental setup based on a 12-detector CsI(Tl) spectrometer (Ω = 0.96 × 4π) is described, which has been used in experiments on measuring σR(E) for reactions with radioactive isotopes of He, Li, and Be. The above methods and the σR(E) measurement results for the 6He + 28Si,59Co,181Ta reactions are analyzed. The advantage of the method allowing for multiplicity of γ rays is shown. [ABSTRACT FROM AUTHOR]

A method for the determination of amitriptyline, a tricyclic antidepressant, in human urine by immunosensors has been developed using supramolecular systems based on hexamolybdenum cluster complexes. These complexes have electrochemical activity and give a stable analytical signal, which was used in the development of amperometric immunosensors. Luminescence and dynamic light scattering methods were used to demonstrate the formation of a supramolecular system of self-organized hexamolybdenum nanoparticles and chitosan molecules. A composite material based on hexamolybdenum cluster complexes in combination with reduced graphene oxide has been developed. The working range of amitriptyline concentrations to be determined by an amperometric immunosensor was 1 × 10–9–1 × 10–4 M, the limit of determination was at a level of 5 × 10–10 M, and the amitriptyline content of urine samples was at a level of (n – 7) × 10–8 M. A comparison of the results of analysis performed using an amperometric immunosensor and a fluorescence polarization immunoassay showed the absence of significant systematic errors. The ability to determine amitriptyline in biological fluids makes it possible to select an optimal therapeutic dose of the drug, that is, to develop approaches to creating personalized medicine. [ABSTRACT FROM AUTHOR]

The essence of the proposed methodology for monitoring the kinetics of damage to a deformed material is to establish a correspondence between micro-, meso-, and macrodamage, and the acoustic emission pulses generated in this case. During the loading process of a product, the recorded pulses are divided into pulse flows of low (H), middle (C), and high (B) energy levels, corresponding to the energy of destruction of structural bonds. By calculating the current values of the partial content of acoustic emission pulses in the H, C, and B clusters generated by micro-, meso-, and macrodamage, and comparing them with the threshold ones established during destruction, the load-bearing capacity current level of a product during loading is determined. Application of the developed methodology for identifying zones of developing damage and assessing the load-bearing capacity of the current state of stringers under loading conditions during interlayer shear tests is considered. [ABSTRACT FROM AUTHOR]

A simple scheme is proposed that allows one to verify the effect of nonlinear properties of an indium-tin oxide film on the transmittance of integrated silicon waveguides. In the proposed implementation, the transmittance of the waveguide depends on the transmitted light intensity. The scheme is adapted for direct experimental verification. To calculate characteristics and optimize geometry, nonlinear Maxwell equations are solved numerically in frequency space. Nonlinearity is introduced into the equations as a general function, without the usual expansion in a series in powers of the field, and is parameterized on the basis of experimental data. Simulation is performed in three-dimensional space. [ABSTRACT FROM AUTHOR]

We study the dependence of the parameters of the evolution of scalarly charged black holes (BHs) in the early Universe on the parameters of field theories of interaction, and the influence of the geometric structure of the relative position of BHs on the limitation of their maximum mass, The problem of the metric of a scalarly charged BH in a medium of expanding scalarly charged matter is discussed, the expression is obtained for the macroscopic cosmological constant at late stages of expansion, generated by quadratic fluctuations of the metric, connecting the cosmological constant value with the BH masses and their concentration. [ABSTRACT FROM AUTHOR]

Due to the abundant dielectric, ferroelectric, piezoelectric, and pyroelectric properties, dielectrics have found extensive applications in various fields. Particularly, the environmentally friendly and lead-free (1 − x)Bi0.5Na0.5TiO3−xBi0.5K0.5TiO3 (BNT-BKT) has attracted wide attention because of its well electrical polarization performance at the morphotropic phase boundary. Currently, so much research has been conducted on the property regulation of the BNT-BKT-based materials. However, there is still limited investigation into the influence of process parameters on electrical behavior using wet chemical methods. Meanwhile, the underlying mechanism also remains unclear. In this work, a series of BNT-BKT samples with fixed proportion have been prepared through adjusting the concentration of alkaline solution in hydrothermal method, followed by a detailed exploration of the microstructure, morphology, and various electrical polarization properties. The results indicate that BNT-BKT samples undergo the transition from rhombohedral to orthorhombic phase with increasing hydrothermal concentration. Moreover, higher concentration can effectively suppress the formation of strip-like grains due to element segregation. Furthermore, the enhancement in growth and stability of electric domains is observed, as well as the intensity and stability of electrical polarization behavior. The findings have guiding significance in performance modulation of lead-free dielectric materials and the design of related electronic devices. [ABSTRACT FROM AUTHOR]

FET-based charge carrier mobility measurements in low-conductivity materials, as well as semiconductor materials with a high density of trapping states, such as nanocrystals and polycrystalline films, are highly distorted due to charge accumulation in the transistor structure. In this work, a comparative study of the measurement of the mobility of charge carrier in conductive polymers, nanocrystals and polycrystalline films, using the analysis of output and transfer characteristics, was carried out. It is shown that using output characteristics instead of transfer characteristics for calculating the charge carrier mobility helps to avoid a systematic error in the measurement. [ABSTRACT FROM AUTHOR]

R-Oxo hydroformylation processes on rhodium phosphite complexes developed at LLC «RN-RD CENTER» are described – selective production of n-butyral from propylene (R-Oxo I), production of a mixture of n-butyral and isobutyral in equal parts (R-Oxo II), selective production of n-pentanal from a mixture of linear butenes (R-Oxo III). A scheme for the hydroformylation of propylene with membrane separation of the catalyst from the heavy reaction products is described.The analysis of the direction of using C3–C5 oxosynthesis products as raw materials for the production of ester lubricants is carried out. [ABSTRACT FROM AUTHOR]

A numerical-analytical method is developed for solving the problem of optimal recognition of a set of possible signals observed in the form of an additive mixture involving not only fluctuation measurement errors (with an unknown statistical distribution law), but also a singular disturbance (with parametric uncertainty). The method not only detects signals in the mixture, but also estimates their parameters as based on a given cost functional and accompanying constraints. Based on the idea of generalized invariant unbiased estimation of linear functionals, the method ensures decomposition of the numerical procedure and autocompensation of the singular disturbance without resorting to conventional state space extension. Parametric finite-dimensional representations of the signals and the disturbance are obtained using linear spectral decompositions in given functional bases. The measurement error is described using only its correlation matrix. The random and systematic errors are analyzed, and an illustrative example is given. [ABSTRACT FROM AUTHOR]

We study the self-gravitating Higgs field of a scalar charge. We show that in the zeroth and first approximation in the smallness of the scalar charge, the gravitational field of the scalar charge is described by the Schwarzschild–de Sitter metric with a cosmological constant determined by the vacuum potential of the Higgs field. An equation for the perturbation of the vacuum potential is obtained and studied. Particular exact solutions of the field equation are given. It is shown that in the case of a naked singularity, solutions of the field equation have the character of microscopic oscillations with a Compton wavelength. Asymptotic limit cases of the behavior of solutions are studied and their comparative analysis is carried out in relation to the Fisher solution. The averaging of microscopic oscillations of the scalar field is carried out and it it shown that at they make a negative contribution to the macroscopic energy of the scalar field, reducing the observed value of the black hole mass. A computer simulation of a scalar field demonstrates various types of the behavior of solutions. [ABSTRACT FROM AUTHOR]

When designing new nuclear power plants, it is important to ensure cost-effective electricity production while complying with safety, reliability, and environmental protection requirements. One of the directions for solving this problem is to improve the equipment of nuclear power plants, in particular the search for the most suitable technical solutions for regenerative high- and low-pressure heaters (HPH and LPH) of steam turbine units (STU). Optimization of water subcooling to the saturation temperature of the heating steam (hereinafter referred to as subcooling) in the STU regeneration stages makes it possible to increase the power of the power unit or reduce the metal intensity of the heaters, depending on the expected economic indicators of the nuclear power plant, which leads to a reduction in the estimated cost of generated electricity. Unification of heaters will make it possible to simplify the processes of design, manufacturing, repair, and transportation of serially produced heat-transfer equipment, improve the layout of the turbine building, and reduce equipment development costs. The article presents the results of calculations of the technical and economic indicators of the heat-transfer equipment of the STU regeneration system type K-1200-6.8/50 LMZ, and draws conclusions about the possibility of finding a preferable solution based on the criterion of annual economic effect. A special feature of the methodology used is the determination of the most appropriate values of water subcooling in surface heaters of the STU regeneration system depending on operating conditions, the situation on the electricity and equipment market, as well as economic policy. The possibility of increasing the economic efficiency of the power unit by optimizing the weight and size characteristics and unifying the heat-transfer equipment of the regeneration system is shown. An additional economic effect can be obtained by using chamber-type heaters in a horizontal design, combining two heating stages in one housing. A promising layout option is that in which the entire LPH group is represented by unified surface-type devices in a horizontal design located in the condenser hood of a half-speed STU. [ABSTRACT FROM AUTHOR]

The magnetization curves of the Y2(FexCo1 –x)17 compounds were measured in the temperature range of 300–923 K along easy and hard magnetization directions. The magnetization curves were analyzed, and the magnetocrystalline anisotropy constants K1, 2 of the samples were calculated. The temperature and composition dependences of the anisotropy constants K1, 2 and the saturation magnetization Ms were discussed. It was shown that, with increasing relative iron concentration in the samples, the first anisotropy constant K1 increases and reaches a maximum value of 5.1 × 105 J m–3 at x = 0.29. [ABSTRACT FROM AUTHOR]

A new property of convex functions that makes it possible to achieve the linear rate of convergence of the Newton method during the minimization process is established. Namely, it is proved that, even in the case of singularity of the Hessian at the solution, the Newtonian system is solvable in the vicinity of the minimizer; i.e., the gradient of the objective function belongs to the image of the matrix of second derivatives and, therefore, analogs of the Newton method may be used. [ABSTRACT FROM AUTHOR]

Scale transformations of cosmological models based on a statistical system of degenerate fermions with a scalar Higgs interaction are studied. The similarity properties of cosmological models under scale transformations of their fundamental parameters are revealed. The transformation laws for the coordinates of singular points and eigenvalues of the characteristic matrix of the dynamical system of the cosmological model under its scale transformations are established. With the help of the transformation to new variables, the previously studied dynamical system of scalar-charged fermions is modified to a dynamical system with a nondegenerate characteristic matrix; for its nondegenerate branch, the singular points and eigenvalues of the characteristic matrix are found, which coincide with the corresponding values for the vacuum field model. Examples of numerical simulation of such cosmological models are given. [ABSTRACT FROM AUTHOR]

The condensation of diethyl phosphite with aldehydes and cyclic ketones under conditions of thermal catalysis and microwave radiation (MW) afforded new amino phosphonates based on secondary amines, including those containing gem-dichlorocyclopropane and cyclic acetal fragments. The optimization of conditions for obtaining the target products using MW radiation showed that dialkylamines are more active than the secondary amines used. [ABSTRACT FROM AUTHOR]

The mechanical properties of materials 3D-printed by wire arc additive manufacturing (WAAM) are studied. Thermal and vibrational treatment is found to decrease the anisotropy and improve the properties of the materials at low temperatures. This implies that heat treatment of small components and vibration treatment will be expedient in other cases. [ABSTRACT FROM AUTHOR]

We presented the results of experimental study of the synthesis of zirconium ceramic coatings partially stabilized with yttrium oxide using the electron-beam method in the forevacuum pressure range (1–100 Pa). The experiments were carried out with a forevacuum plasma-cathode electron source operating in the elevated (forevacuum) pressure range. In a high vacuum, at the initial stage of electron-beam heating and evaporation, the dielectric target can be charged to almost the full accelerating potential. This, in turn, negatively affects the efficiency of energy transfer from the electron beam to the irradiated target. The currently developed forevacuum plasma-cathode electron sources operate at a pressure of several to hundreds of Pascals, which is an order of magnitude higher than the operating pressure of hot-cathode or common plasma electron sources. The beam plasma generated in this range of pressure eliminates the charging effect of the dielectric target. Thereby practically all power of the electron beam is transferred to heating, facilitating evaporation of any refractory dielectric materials. The synthesized coatings with a thickness of over 100 µm were studied, and their mechanical and thermal conductive properties were measured. [ABSTRACT FROM AUTHOR]

We presented the algorithm for ARC-PVD coating thickness calculation and rotation speed optimization. This approach was used to improve the coating thickness uniformity of complex surface samples. Established that the selected rotation speed increased the thickness uniformity from 0.5–9 µm range to 2–8.5 µm. Microhardness increased by an average of 30% compared with basic rotation speed. Scratch tests and roughness measurement did not have any significant changes. [ABSTRACT FROM AUTHOR]

The K + → π + π 0 π 0 γ decay is observed by the OKA collaboration. About 60 events of the decay observed with signal:noise ≈ 1 . The branching ratio obtained by normalization to K + → π + π 0 π 0 is measured to be (3.7 ± 0.9 (s t a t) ± 0.3 (s y s t)) × 10 - 6 for E γ ∗ > 10 MeV . The branching ratio, γ energy spectrum and angular distribution are consistent with ChPT prediction. [ABSTRACT FROM AUTHOR]

A method for quantitative evaluation of the porosity in carbon fiber reinforced plastic (CFRP) structures based on laser excitation of probe ultrasonic pulses is presented. The technique of estimating the porosity level in a material has been proposed using the experimentally measured phase velocity of longitudinal acoustic waves propagating in this material. By the example of control samples and actual CFRP structures, the possibility of obtaining maps of the local porosity distribution in the studied region of the structure has been demonstrated. It has been shown that in the structures studied, there are regions with a significant variation in the local porosity level. The proposed method can be used for quality monitoring of manufactured composite structures, as well as for studying the structural changes during operation of the structure. [ABSTRACT FROM AUTHOR]

The study of the fractal properties of the surface of Nd100 – xFex alloys in a wide range of concentrations х (х = 20–90) was carried out in the framework of the fractal thermodynamics model. To this end, we performed an analysis of scanning electron microscopy images of the surfaces of a series of Nd100 – xFex alloys synthesized by induction melting. A high degree of proximity of the surface structure of all the studied samples, both before and after etching, to fractals is shown. The values of the parameter δ characterizing the relative deviation of the studied samples from the fractal are in the range of 0.017–0.029. Three-dimensional diagrams of the fractal parameters Sf, Tf, Ef, and x and two-dimensional diagrams of the same parameters Sf, Tf, Ef, and x reflecting the nature of the state of the surfaces of Nd100 – xFex alloy samples before and after etching are constructed. For all investigated alloy samples, the values of the parameters of the fractal equations of state are calculated. The correlation of the maximum value of the coercive force Hc = 4.8 kE with the values of fractal entropy Sf = 39.86, fractal temperature Tf = 529, and fractal dimension D = 2.6530 of the Nd100 – xFex alloys at x = 20 has been established. [ABSTRACT FROM AUTHOR]

The base-catalyzed reaction between 4-phenyl-1H-imidazole-2-thiol and 1,5-diaryl-substituted (E)-pent-2-en-4-yn-1-ones proceeded with the involvement of the C≡CCH=CH moiety of the substrate and HS, HN groups of the reagents to give 5H-imidazo[2,1-b]-[1,3]thiazine derivatives (6-endo-trig cyclization). Under the same conditions, the reactions of these linearly conjugated enynones with 4,5-diphenyl-1H-imidazole-2-thiol proceeded with the furan ring closure (5-exo-dig cyclization). The difference in the reaction pathways involving 4-phenyl- and 4,5-diphenyl-substituted 1H-imidazole-2-thiols was explained by the steric effects arising in the transition state. [ABSTRACT FROM AUTHOR]

The review summarizes and analyzes information regarding the effect of nanoparticles (NPs) of metals, metal oxides and carbon on the biofilm formation and mature biofilms of microorganisms. The viability of individual microbial cells, including direct disruption of cell surface structures and oxidative stress associated with the formation of reactive oxygen species (ROS), as well as the effect on the production of the exopolymer matrix and the quorum sensing system are considered as the mechanisms of NPs action on biofilms. The effects of silver NPs, gold NPs, some metal oxides, and carbon nanomaterials on microbial biofilms have been described in more detail. The effects of metal and carbon NPs on microbial biofilms are compared. Both antibiofilm and probiofilm effects of NPs are noted, depending on their nature, and the prospect of their use as antimicrobial agents and carriers for the production of microbial biofilms of biotechnological significance are considered. [ABSTRACT FROM AUTHOR]

The Сd(II) complexes with redox amphoteric 2,6-di-(tert-butyl)-4-((2-hydroxyphenyl)imino)cyclohexa-2,5-dienone ligands L1 and L2 (adducts I, II, and III) are synthesized. The structures of coordinated complexes I, II, and III are determined by X-ray diffraction (XRD) (CIF files CCDC nos. 1838319 (II) and 1838310 (III)) and confirmed by the 1Н, 13С, and 113Cd NMR spectroscopy (for complexes I and III) and IR spectroscopy data. [ABSTRACT FROM AUTHOR]