Polymerization of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane is the main method for manufacturing methylphenylsiloxane rubbers, and copolymerization of octamethylcyclotetrasiloxane and 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane is the main method for production of high- and low-molecular weight dimethylmethylphenylsiloxane rubbers. The molecular weight, viscosity, and other properties of the obtained polymers depend on the purity of cyclosiloxanes. The technology of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane production by thermocatalytic decomposition of methylphenylsiloxanes in the presence of lithium hydroxide or lithium silanolate, followed by vacuum rectification, makes it possible to obtain a product containing 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclotetrasiloxanes, tetraphenyldimethyldisiloxane as impurities and trace amounts of phenyl-containing siloxanes of cyclic and linear structure. The impurities of polycyclic and polyhedral structures have not been previously described. In this study, the method of gas chromatography-mass spectrometry is used to analyze compounds that can be present as impurities in technical-grade 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane. The use of the previously described regularities of the fragmentation of siloxanes of different structures made it possible to identify a number of siloxanes which are absent in the NIST 11 mass spectra library. It is shown that polycyclic and polyhedral compounds containing methylsilsesquioxane units have a short fragmentation path. They are characterized by ionization with the elimination of the methyl group and benzene in case of two phenyl groups in the molecule. The siloxane skeleton of such cations is rather stable, so they more readily lose another methyl group thus transforming into double-charged cations. The impact of electron ionization on the molecules with siloxane units containing different organic substituents at silicon leads to randomization of those substituents and rearrangement of the siloxane skeleton. Analysis of the results revealed that silanes, siloxanes of linear, cyclic, polycyclic and polyhedral structures are present in technical grade 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane.

The impurities contained in lead and lead-based alloys, which are widely used in various branches of industry, i.e., nuclear, medical, electrical engineering, etc., affect their physicochemical properties which necessitates developing of the reliable method for the impurity determination. Photometric, spectral, and chemical — spectral methods used to address this problem are labor-intensive and do not always have the required sensitivity. A method of inductively coupled plasma mass spectrometry (ICP-MS) coupled with High Matrix Introduction (HMI) technology has been proposed as alternative easy to use procedure designed to be more sensitive. The Agilent HMI Sample Injection System provides inline dilution of the sample aerosol (supplied from the spray chamber to the burner) with pure argon. This method of sample introduction provides for analysis of the solutions with a solute content of up to 1% and higher. The aerosol dilution reduces concentration of the matrix and solvent at the inductively coupled plasma interface without conventional dilution. In this case, the matrix suppression of impurities is almost eliminated and CeO⁺/Ce⁺ is reduced to 0.2%, while the typical CeO⁺/Ce⁺ ratio for the Agilent 7500 mass spectrometers is 1 – 2%, but no more than 3%. We present application of this method to the analysis of Mg, Ca, Fe, Cu, As, Ag, Sn, Sb, Bi in lead by an Agilent 7500cx ICP-MS with preliminary acid digestion of lead samples in a microwave autoclave. The use of the HMI system made it possible to exclude the stage of sample dilution, reducing the possibility of sample contamination with a diluent, and to determine the content of impurities in a highly concentrated matrix at a level of 10^–4 – 10^–5 %. The efficiency of the method, as well as the possibility of using multi-element standard solutions prepared with 1% nitric acid for analysis of the samples with high lead content is shown.

The largest deposits of graphite in the Russian Federation are located in the Middle and South Urals. However, several manifestations, e.g., «Opytnyi» sector, which have not yet been placed under production, require substantiation of the strategies for their integrated development, which, in turn, requires gaining the reliable data on the content of graphite in carbon-containing rocks. A method for simultaneous determination of organic and native carbon in carbon-containing rocks using an ELTRA CW MULTIPHASE carbon and water analyzer is proposed. The method is based on the combustion of organic carbon (coal, shale) in a stream of oxygen at 550°C and native carbon (graphite) in the temperature range 550 – 1000°C with subsequent IR-spectroscopic determination of the content of gaseous carbon dioxide. The interfering effect of magnesium carbonate and calcium carbonate on the determination of organic and native carbon was taken into account in the calculations. The carbonate content was determined using a separate sample in a nitrogen flow by decomposition of magnesium carbonate at 550°C and calcium carbonate within a temperature range of 550 – 1000°C. The content of chemically bound water in the composition of the minerals of carbon-containing rocks, was determined simultaneously with carbon. The only one type of carbon — graphite — was observed in the studied samples of the carbon-containing rock from «Opytnyi». The different combustion capacity of graphite was revealed: some of the crystals almost completely burn out at a temperature below 800°C and others above 800°C, which suggests the presence of cryptocrystalline and explicit crystalline graphite in the rocks. The developed method is rapid and corresponds in accuracy to the method for native carbon determination ±0.27 C % – 0.01 C % developed and approved by the Research Council for Analytical Methods of Research (NSAM).

The rheological properties of polymer systems determine their deformation behavior and the relationship between stresses, strains and strain rates. We present the results of determining the melting points of solid polymer compounds by the rheological method. Tests were carried out using a rotary rheometer in an oscillating mode. Using the obtained thermomechanical dependences, the experimental data were compared with the values determined by standard analytical (capillary method) and thermal (differential scanning calorimetry) methods. The viscous and elastic behavior of the samples were analyzed using the dependence of the oscillating stress or strain on the angular velocity or frequency. It is shown that the temperature dependences of the storage and loss moduli, as well as the angle of mechanical losses, determine the physical and relaxation transitions in polymers upon their heating. The obtained results can be used in analysis of the effect of conditions of polymer processing on their properties, as well as in optimization of the technological processes of product manufacture and modeling the behavior of materials under operation conditions at the stage of development.

Developing of nanotechnology-based electronics entails developing of new carbon nanocrystalline materials with predetermined physicochemical properties, e.g., obtained by synthesis of polyacrylonitrile (PAN) in conditions of heat treatment. We have studied the properties of PAN heat-treated in air in the temperature range 150 – 250°C and the effect of stabilization on the kinetic parameters of synthesis and thermochemical properties of carbon material upon heat treatment in N₂ atmosphere. It is shown that an increase in the temperature of a preliminary treatment up to 200°C leads to a decrease in the activation energy and pre-exponential factor compared to the corresponding values characteristic for the initial polymer (from 90.9 and 3.1 × 10⁶ to 53.3 kJ/mol and 1.1 × 10³ min^–1, respectively), which indicates to the occurrence of diffusion limitations. When the temperature of a preliminary treatment in air increases from 180 to 250°C, the difference between temperature peaks for DSC and TGA curves decreases due to appearance of a «core-shell» structure. XRD data indicate that the initial PAN structure does not change up to 150°C. Further increase in the temperature leads to significant changes in the initial structure of the polymer which are manifested in a decrease in the peak area in the X-ray diffraction pattern of the polymer. The results obtained can be used in the development of a method for the synthesis of carbon materials with controlled properties predetermined at the stage of stabilization.

An increase in the strength of steels is associated with a decrease in the content of impurities, which have a negative effect on the mechanical properties of steels. One of those impurities is hydrogen. It is known that at ultrahigh frequencies, due to the peculiarities of the distribution of alternating current over the cross section of a metal conductor, the conductivity is carried out by a thin surface layer (skin-effect). We present the results of using high-frequency currents for determination of the hydrogen content in a metal. The absorption of hydrogen by thin subsurface layers of steel is determined proceeding from a change in the voltage drop across the samples which depends on the resistance of the layers. The voltage drop as a function of the alternating current frequency is measured using a high-frequency generator, an HF-voltmeter, and an HF-galvanometer. Wire samples made of high-quality U8A carbon steel were used during testing procedure. At the same time, the amount of hydrogen absorbed by the steel was determined by the method of anodic dissolution. It is shown that the cathode-introduced hydrogen is unevenly distributed over the cross section of the sample. During the aging of cathodic hydrogenated steels of a U8A type, hydrogen diffusion from steels into the air takes place with an insignificant penetration of hydrogen into the deeper metal layers. Moreover, the hydrogen content and the resistance of the subsurface layers of the material increase with an increase in the current density during cathodic polarization. The results obtained can be used in nondestructive testing of the degree of hydrogenation of ferromagnetic products.

Operational integrity of structures under complex combined modes of a loading depends on a significant number of combinations of operational parameters of thermomechanical impacts in part of loads, temperatures, duration, number of cycles, and deformation rates. The main laws governing the deformation of structural materials under complex loading are determined in conditions of combined standard, unified and special tests in laboratories. Using representative substantiations of physical and mechanical models for deformation diagrams in a wide range of loading conditions, taking into account the different scales of models, the structure of materials and the responsibility of structures, a stepwise consideration of the corresponding types of deformation is proposed: elastic, sign-variable flow, progressing accumulation of strains and their combination. At the same time, calculations of the structures can be carried out in the form of a hierarchical system in which each next level specifies the boundaries of permissible impacts towards expansion of the range of acting loadings, temperatures, rates and modes of deformation, which entails an increase in the bulk of the required initial data and complicates the calculations. The proposed methods of schematization of the physicomechanical properties and types of the equations of state for description of the deformation curves take into account the requirements of compactness of the initial data and the need of using both standard and unified methods for determining the characteristics of cyclic inelastic deformation and special methods as well. To describe the kinetics of deformation diagrams under aforementioned conditions both from the theoretical point of view and from the point of view of practical applications, power equations appeared most suitable; to reflect the role of the temperature factor exponential dependences should be used; whereas power dependences are useful to take into account time factors, strain rate, and conditions of two-frequency loading. The refined calculations at the higher and more complicated steps of the considered hierarchy providing the maximum possible use of the deformation and strength reserves of the materials and structures are to be based on the kinetic laws describing processes of low cycle deformation under complex modes of loading.

The goal of the study is to consider the effect of explosion welding, heat treatment and cold straightening (gagging) in production of 09G2S + 08Kh13 bimetal with a butt welded joint in the cladding layer on the evolution of residual internal stresses. The impact of technological operations on the change in the level of residual stresses in a bimetallic material with a welded butt joint in the cladding layer was carried out using a non-destructive method of the magnetic memory of metals (MMM). This method is based on the use of the intrinsic stray magnetic field formed in the zones of increased dislocation density. The results revealed the special features of the location of zones with maximum values of the stress field gradient (dH/dx) and their evolution upon production of 09G2S + 08Kh13 bimetal with a butt welded joint in the cladding layer. An increase in the level of residual stresses in the cladding layer occurs after manual electric arc welding of 2 parts of the cladding layer made of 08Kh13 steel. It is shown that after explosion welding the level of residual stresses change. The stress relaxation occurs in the zone of weld in the cladding layer. At the same time, an increase in the level of residual stresses is observed in the main and cladding layer of the bimetal. To reduce the high level of residual stresses, we used the subsequent heat treatment of the obtained bimetallic samples in two different modes. The optimal heat treatment mode (heating to 720 ± 20°C, holding for 2 h, cooling with a furnace) which excluded the crack formation in the cladding layer upon mechanical straightening of bimetal was specified for 09G2S + 08Kh13 bimetal sample with a butt welded joint in the cladding layer.

An analytical formula for a smooth description of the tension diagram of EK-181 steel and a method for rearranging the diagram when changing the direction of deformation are proposed for the first time. The process of straightening a quarter of an annular sample and further stretching is numerically modeled. It is shown that the conditional yield strength of the material of the straightened sample is 7.5% less than the actual conditional yield strength of steel. It is shown that the test for pure bending of a cantilever sample in the form of a semicircle with the processing of the bending diagram (by analogy with GOST 3565–80 for torsion) provides an estimate of the conditional yield strength which is 32% higher than the actual yield strength. The possibility of numerical reconstruction of the tension diagram from the diagram of pure bending of a cantilevered semi-ring sample is proved. It is shown that this procedure really gives the value of the conditional yield strength of steel EK-181 with a tolerance for the residual deformation of 0.2%. The analysis of the test procedure for the rings of fuel element cladding and the proposed algorithm for determination of the conditional yield stress of the ring material is carried out. Attention is drawn to the arbitrariness of the choice of the designed load on the two-stage diagram of the diametrical tension of the ring and to the lack of scientific substantiation of the possibility of determining the yield stress on the second part of the diagram. It is shown that this method in the current form contradicts GOST for tensile testing due to the absence of a base with a uniform stress state on the ring. Therefore, the considered method is not recommended for determining the values of the conditional yield strength suitable for strength calculations.

We report on solving the problem of forming a Russian-language text collection (dataset) consisting of bibliographic descriptions of scientific articles for training classifiers. Various approaches to creating such collections are considered. The expediency of using expert estimates for assigning class labels is assessed. The known datasets are analyzed, the requirements for the generated text array are formulated, and the choice of the subject area (Computer Science) is justified. We propose a technology of forming collection in conditions of the shortage of Russian-language articles. To do this we use automated translation of publications (bibliographic descriptions) from available English-language electronic libraries (ACM digital library, IEEE Xplore digital library, CiteSeerX) with additional expert quality control of the translation. The bibliographic collection thus formed was studied using methods of clustering (Latent Semantic Analysis) and visualization (Principal Component Analysis). Training and test samples were compiled and «standard» classifiers (K-Nearest Neighbor Method, Logistic Regression, Random Forest) were used. Then we calculated standard quality measures (accuracy, precision, recall). The rigid and soft classification were carried out. For rigid and soft classification all calculated measures (for the studied classifiers) ranged within [0.79; 0.87], and [0.91; 0.95], respectively. The experiments showed almost identical results for Russian and English bibliographic descriptions (the difference did not exceed 2%). The proposed method of forming text collections reduces the complexity of the labeling process compared to the expert approach, solves the problem of the lack of Russian-language documents, allows formation of sufficiently large balanced bibliographic datasets for training and testing classifiers.