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Purpose. The article presents the results of a comprehensive analysis of iron ore fragments found during the explorations of mound no. 51 of the Ust-Tartas site (Vengerovsky distric, Novosibirsk region). The fragments presented shapeless rock debris with ferruginous oxides and a specific. Two fragments turned out to be slag. Three fragments come from burial no. 17 while others were found in the mound fill and the arable layer, obviously moved from their original location. The samples were studied using binocular microscopy, X-ray phase analysis and scanning electron microscopy with energy-dispersive spectrometry.Results. According to the study, the presented goethite ores samples were classified as sedimentary swamp-lake ores of regional and local origin, which is characterized by a lower melting point and high quality of smelted iron. Apparently, the region landscape features made it possible to extract bog ore in the immediate vicinity of the places where the craftsmen lived. It has been suggested that the identified artifacts the professional activity of a Sargat community related to metal production, buried in the investigated mound or participat in the funeral ceremony.Conclusion. The studied site is of great scientific importance for the study of the Sargat culture, as a whole, and the phenomena associated with the Sargat society life. The importance of the methodological component of the samples study should also be emphasized.

Here we report a case of EBV-positive lymphoepithelioma-like carcinoma of the abdominal and retroperitoneal lymph nodes in a 17-year-old girl. This case is of special interest because of the rarity of the diagnosis (especially in adolescents), the unusual location of the tumor, the patient’s history of infections and autoimmune diseases (autoimmune hepatitis, Crohn’s disease) and the absence of standard treatment guidelines for this tumor. The patient and her legal representatives gave their consent to the use of the patient’s data, including photographs, for research purposes and in publications.

The effect of barothermal (HPHT) treatment on the structure and properties of carbides of refractory metals and their alloys is considered. The principal directions of studies are determined. The comparative analysis of data measured in studying the mechanical properties of WC–Co hard alloys after sintering at high pressures and temperatures is performed. It has been established that the crucial role in the formation of the structure and mechanical properties of WC–Co alloys in the process of HPHT treatment is played by the process temperature under constant pressure conditions.

The scientific basis for the development of working materials from waxy highly filled composites for FDM 3D printing using is not yet sufficiently developed. The need to develop such composites is due to the fact that highly filled waxy composites, on the one hand, have low 3D printing temperatures, and on the other hand, the fact that the waxy substance has a low ash content and is completely removed during annealing and subsequent sintering of the residual framework from the filler. Therefore, in this work, the influence of the binder content on the physical and mechanical properties of composite materials such as metal powder - waxy substance in the ratio of metal to waxy substance, as 50/50, 60/40, 70/30, 80/20 % (by volume), as well as the shape change of composite samples when they are heated at a temperature from 61 to 230 °C. Carbonyl nickel and carbonyl iron were used as metal powder, and beeswax and paraffin were used as a binder. It was found that the developed surface of particles significantly affects the density dependence, the microhardness and compressive strength of composites from the binder content, the actual density of the composite samples after pressing is less than the calculated by the additivity formula with the binder content up to 40 % (by volume) and only with an increase in the binder content to 50 % (by volume) does the actual density approach the calculated additive; the developed surface of nickel particles several times increases the strength of the composite in comparison with iron at the same binder content, at the same time, the dependences of the microhardness differ significantly: on Ni-wax samples, it tends to decrease with an increase in the wax content, and on samples Fe-paraffin - to an increase, which is due to the influence of such phenomena as adhesion and cohesion, mechanical adhesion. The level of strength of composite samples with a binder content of 40-50 % (by volume) is sufficient so that they do not collapse not only in 3D print head The resulting experimental data can be extended to other similar systems when creating working materials for FDM 3D printing based on carbonyl nickel and iron powders.

We study the corrosion and tribocorrosion behaviors of hard alloys of the VN20 + Cr3C2 and VN20 + VC systems in solutions based on 3% NaCl with different рН values. In alkali media, the corrosion currents and friction coefficients are lower than in acid media, which is explained by the inertness of nickel. The VN20 + 1 wt.% Cr3C2 alloy has the highest corrosion and tribocorrosion characteristics.

Residual thermal stresses in a three-phase cermet composite with a layer-structured refractory component (WC-coated SiC grains) are studied by analytical methods. The layer of residual thermal stresses in such alloys is found to significantly depend on the composition and volume content of the layers and binder phases. The data obtained for the alloys with a large amount of the binder phase are in good agreement with the results of calculation by a different numerical model.

The influence of the surface layer on the process of the electrochemical deposition of metals and semiconductors into porous silicon is studied. It is shown that the surface layer differs in structure and electrical characteristics from the host porous silicon bulk. It is established that a decrease in the conductivity of silicon crystallites that form the surface layer of porous silicon has a positive effect on the process of the filling of porous silicon with metals and semiconductors. This is demonstrated by the example of nickel and zinc oxide. The effect can be used for the formation of nanocomposite materials on the basis of porous silicon and nanostructures with a high aspect ratio.

We have developed a sensitivity analysis permitting effective estimation of the change in the impulse responses of a microthrusters and in the ignition characteristics of the solid-fuel charge caused by the variation of the basic macrokinetic parameters of the mixed fuel and the design parameters of the microthruster’s combustion chamber. On the basis of the proposed sensitivity analysis, we have estimated the spread of both the propulsive force and impulse and the induction period and self-ignition temperature depending on the macrokinetic parameters of combustion (pre-exponential factor, activation energy, density, and heat content) of the solidfuel charge of the microthruster. The obtained results can be used for rapid and effective estimation of the spread of goal functions to provide stable physicochemical characteristics and impulse responses of solid-fuel mixtures in making and using microthrusters.

We propose a method for characterizing and choosing solid mixed fuels for use as the solid-fuel charge of microthrusters of microelectromechanical systems. The method is based on the solution of the problem on the dependence of impulse responses of such a microthruster on the diameter of the outlet cross-section of its combustion chamber and the microkinetic parameters of the fuel. The variants of choosing the above fuels have been illustrated using glycidyl azide polymer/RDX as the example of a solid fuel mixture. The paper presents the characteristic criteria determining the composition of mixed fuels for the microthruster of a microelectromechanical system and considers the main types of "direct" and "inverse" problems arising in characterizing and choosing such fuels.

On the basis of macrokinetic calculations, the influence of the initial temperature on the impulse responses of the processes of ignition and combustion of the solid-fuel charge of the microelectromechanical system (MEMS) microthruster burning the solid fuel glycidyl azide polymer (GAP)/RDX has been investigated. It has been established that fuel heating/cooling in a wide range of temperature values from 150 to 450 K characteristic of the conditions of a satellite in orbital flight markedly affects both the thrust and the total impulse of the MEMS microthruster. In so doing, an increase in the initial temperature leads to a marked decrease in the induction period and an increase in the critical flux of fuel ignition. The influence of the change in the initial temperature on the self-ignition temperature of GAP can be neglected. To obtain stable characteristics of the microthruster, it seems expedient to use a thermostating system.

The process of ignition of the solid fuel from glycidyl azide polymer in the mini-engine of a microelectromechanical system has been considered. Macrokinetic calculations of the self-ignition temperature of the fuel and the induction period for different heat transfer conditions have been made. On the basis of the critical thermal flux determination, recommendations on the choice of the minimum power and size of the thermistor in the igniter of the solid-fuel mini-engine have been formulated.

On the basis of thermodynamic calculations we show that solid-fuel mixtures glycidyl azide polymer/RDX are promising for use in miniengines made on the basis of technologies of microelectromechanical systems of semiconductor microelectronics. It has been shown that small (up to 20 mass percent) additives of RDX to the glycidyl azide polymer markedly increase the values of the theoretical specific impulse and the thermal efficiency of the engine and decrease the quantity of undesirable solid carbon formed in combustion products of the mixed fuel. In so doing, these mixtures provide fairly low combustion temperatures not exceeding the thermostability limit of crystal silicon from which the miniengine case is made. The physicochemical factors influencing the value of the theoretical specific impulse of the mixed solid-fuel charge have been elucidated, and methods for its maximization have been proposed.

The densification kinetics of a powder system has been described by a relatively simple analytical expression, which consists of only two dimensionless parameters. The first of them has been shown to be equal to the ratio between the maximum rate of the linear contraction and the total contraction of the sample multiplied by the time, for which the densification takes place; the second has been found to be equal to the ratio of the time required for the attainment of the maximum contraction velocity to the total densification time. The densification rate vs. time diagram is given by a curve having one or two maxima depending on values of the parameters entering the model. The study has been aimed at modeling the densification in sintering hard alloy mixtures.

Software for speech signal research in patients with malignant diseases of the throat is considered in this work. Basic windows of this system are discussed. These windows represent voice parameters set by a speech therapist to diagnose the disease and to make a decision concerning therapy and rehabilitation.

A system for the ultrasonic (US) control of large hard alloy articles developed in the Institute of Superhard Materials of the Ukrainian National Academy of Sciences is described. Ultrasonic control detects defects with a size from 0.3 mm in the sintering stage, which substantially reduced the number of damages in critical friction units. We investigate the influence of the structure on the sound velocity, modulus of elasticity, and damping properties of VK6 and VK8 hard alloys supplied by different producers.

The structure of speech dialogue systems is analyzed. It is shown that the creation of speech recognition and synthesis systems is connected with the solution of direct and inverse problems as applied to the organization of speech dialogue. Attention is paid to the multilevel hierarchical organization of speech dialogue systems in which the interaction between recognition and synthesis channels is realized through a common knowledgebase. A generalized structure of data representation at different hierarchy levels is analyzed, and the hierarchy of qualities determining properties of a dialogue system is considered.

Experimental results are discussed of the laboratory investigations into high-temperature mechanical properties of WC-Co hard metals as functions of the microstructure parameters (cobalt content, average sizes of carbide grains and cobalt interlayers), binder composition (carbon and cubic carbide contents) and the thermal and force action found in the literature. The effect of high temperatures on deformation characteristics in bending, tension and compression has been analyzed. The problems of short-and long-time strengths (high-temperature strength) and thermomechanical fatigue are discussed. The revealed mechanisms of the high-temperature deformation are considered.

Analytical approach to determining strength of the polycrystalline tungsten monocarbide in tension is evolved from the results of microstress analysis in the polycrystal. The self-consistency method with account of residual thermal stresses has been used as the calculation scheme. The ultimate strength in tension is defined by the condition for equality of the maximum tensile stresses at the grain boundary at the instant of compression or tension fracture. The agreement between the calculated and experimental results is fairly good.

Ordered nickel nanowire arrays formed by electrochemical deposition in a mesoporous silicon matrix have been studied by the ferromagnetic resonance technique. It is established that the samples exhibit uniaxial magnetic anisotropy of the easy-axis or easy-plane type depending on the matrix porosity. Values of the anisotropy field and g-factor in the samples are determined.

Er3+ and Yb3+ ions are introduced into porous silicon films, stabilized by oxidation in an oxygen plasma, in the form of a gadolinium oxychloride-based luminophor by means of thermal diffusion. An investigation is made of the luminescence and photoexcitation spectra of samples with Er3+ (10 and 30 wt.%), Yb3+ (10 wt.%), and Er3, Yb3++ (10 wt.% each). It is shown that the intense IR luminescence (1.00 and 1.54 μm) is caused by cross-relaxation effects. The most effective excitation of the luminescence has been observed in the UV absorption band of the porous silicon.

Based on investigation of the interaction of hard-alloy components with hydrogen and methane—hydrogen medium, new, efficient, and ecologically clean processes which do not involve the use of traditional carbon black have been developed. These processes enable the production of tungsten carbide powders with various particle sizes, and sintered carbides having a controlled carbon concentration and special properties. They also can be used to produce regenerated WC—Co hard alloys whose properties are not inferior to those of the standard materials.

We suggest a method of contact fatigue testing of cemented carbides. It involves cyclic loading of a specimen (half-space) with a flat circular punch by a pulsating compressive stress. Both the loading punch and the test specimens are made of cemented carbides. It is found that the parameters of contact fatigue of a cemented carbide include the depth of the punch penetration into the specimen, σ, after a given number of cycles, the form of the dependence of the penetration depth on the number of cycles, the number of loading cycles between abrupt changes in the growth of the σ values, and the number of these changes. With these parameters determined by laboratory tests on small specimens, we can predict the durability of large carbide components subjected in operation to contact cyclic loads.

We obtained porous silicon films modified at room temperature by an Eu3+-containing polymer complex. The most intense photoluminescence of Eu3+ implanted in the porous silicon was observed at the wavelengths of 611, 618, 691, and 704 nm. In this case, the intensity of the intrinsic photoluminescence of strongly irradiated specimens of porous silicon decreased, while the intensity of weakly emitting films multiply increased. An investigation of the photoexcitation spectra made it possible to establish the effect of Eu3+-containing complexes on the mechanism underlying the excitation of photoluminescence of porous silicon.

Tungsten carbide synthesis in a methane-hydrogen medium have been studied and the conditions for obtaining WC power with no free-carbon impurity determined. Hard alloys based on a “gas” carbide have been shown to exhibit high ductility. The results of the study have been used to develop a commercial process to produce high-ductile hard alloys for high-pressure equipment, stamping dies, and drilling tools.

A photoluminescence (PL) study is carried out on porous silicon (PS) layers of 50 to 60% porosity which are anodically oxidized in ethylenglycol NH4NO3 electrolyte. Such oxidation is found to make the PL intensity stronger and the peak wavelength shorter. The emission of partially linearly polarized light is observed for PS samples under linearly polarized light excitation. Transmission IR and reflectance spectra are recorded to characterize porous silicon. As a result, a strong shift of the absorption band edge and high silicon oxide content are found in PS sampl. This shift is supposed to be due to the quantum confinement mechanism, but the features of PL speak in favour of the important role of oxide in the light emission from PS. In particular, the polarization of the emitted light can be due to the oxide-induced elastic strains.

Porous silicon layers were produced by electrochemical etching of single-crystal silicon wafers with the resistivity 10 Ω cm in the aqueous-alcohol solution of hydrofluoric acid. Raman spectroscopy and infrared absorption spectroscopy are used to study the processes of interaction of porous silicon with undiluted acetylene at low temperatures and the processes of oxidation of carbonized porous silicon by water vapors. It is established that, even at the temperature 550°C, the silicon-carbon bonds are formed at the pore surface and the graphite-like carbon condensate emerges. It is shown that the carbon condensate inhibits oxidation of porous silicon by water vapors and contributes to quenching of white photoluminescence in the oxidized carbonized porous silicon nanocomposite layer.