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A series of heterometallic tetrahedral cluster complexes with the general formula [{MxRe4−xSe4}(CN)12]n− (M = Mo, W; x = 2, 3) were obtained using the reaction of ReI3 and MO3 with selenium and KCN at elevated temperatures. Compounds [ReW3Se4(CN)12]6− and [Re2W2Se4(CN)12]6− are the first rhenium–tungsten heterometallic clusters. Crystal structures, electrochemical properties in aqueous solutions and magnetic properties of crystalline samples have been studied in detail. It has been shown that new cluster anions demonstrate a regular change in geometric characteristics and redox potentials depending on the composition of the cluster core.

Quasi-2D layers of transition metal dichalcogenides are promising candidates for creating saturable absorbers for pulsed lasers. However, the peculiarities of intense electromagnetic radiation’s influence on such structures have not been thoroughly studied. This paper explores the dynamics of photoexcited carriers in WSe2 flakes through experimental studies. These studies found that WSe2 flakes significantly change their optical properties under the influence of a high-power optical pump, allowed estimating the thermalization time of these structures (about 2 ps), and found that full relaxation takes more than 10 ps. The concentration of carriers in the semiconductor surface layer was estimated to be about 1028 m–3. It was found that standard description models of the optical response based on exciton resonances and absorption by free carriers could not adequately describe the experiments’ results. Thus, for an accurate description of the optical response, it was necessary to consider the effects associated with Coulomb screening that are caused by the high concentration of photo-excited carriers of the optical pumping densities used in this experiment.

The objects of research are oligomers-hardeners obtained by aminolysis of secondary polyethylene terephthalate (PET) and polycarbonate (PC) household waste with an aliphatic amine (PEP).The epoxy-diane resin of the ED-20 brand was chosen as the binder cured by the obtained oligomers due to its availability, good properties, acceptable viscosity, and wide applicability. The study of some parameters of the curing of thermosetting resin by industrial and synthesized hardeners is carried out.The gelation times at elevated temperatures (in the range from 50 to 100°C) and the activation energies of epoxy compositions were determined, and the conversion of epoxy groups during curing at room temperature was studied. The analysis of the obtained data showed that the structural features of macromolecules caused by the introduction of PET and PC fragments have a negligible effect on the activation energy and affect only when cured at room temperature and increase the viability of the compositions, while the gelation time at elevated temperatures in the case of all the studied hardeners is almost the same.

The research continues the direction of intensification of glass-making processes by completely replacing soda ash in the glass batch with sodium hydroxide to obtain a well-classified intermediate two-component raw material. A method for obtaining a modified synthetic raw material (SRMm) for producing sodium-calcium-silicate glass based on quartz-containing raw material and sodium hydroxide is considered. SRMm consists of two parts, the chemical composition of one of which corresponds to the low-melting eutectic on the Na2O-SiO2 diagram, in contrast to the prototype SRM, the chemical composition of which corresponds to the chemical composition of silicate glass. The products of the synthesis of parts of quartz sand and sodium hydroxide are mixed with the rest of the components of the glass batch of alkali-silicate glasses, followed by possible agglomeration by known methods. The results of a comparative X-ray phase analysis of experimental charges, as well as heat-treated pelletized samples, show more pronounced glass formation processes in a charge based on SRMm than using the prototype. The use of experimental charges can intensify the physicochemical reactions at the stage of melting in a glass-making furnace, reduce the maximum melting temperature of glass, reduce the carryover of dust-like components of the charge and the technogenic load on the environment.

A two-phase control system designed for thermally regulating the electronic equipment of the spacecraft is presented. The system comprises three capillary pumps installed in parallel, a common radiator and a radiant subcooler. Two capillary pumps are identical, while the third, smaller in volume and overall dimensions, functions as an active temperature controller. The system is equipped with measuring equipment for facilitating experimental work.

Results of studies on predicting the biological activity of N-vinylsuccinimide and N-vinylpyrrolidone monomers using the PASS Online web resource and the CurveExpert program are presented. The possibility of assessing the biological activity of their polymeric derivatives is shown. It is found that monomers and polymers based on them have their own biological activity. The influence of the nature of initiator and polymerization degree on biological activity of polymers is considered.

An analysis of the required conditions for increasing the productivity of a thin slab caster is carried out. Theoretical and experimental findings reveal the main factors preventing an increase in the teeming rate. Quality indicators of concast slabs with a thickness of 90.5 mm are improved by upgrading the roller guide in the CCM segments by an increase in the number of rollers with a decrease in their diameter on the basis of the casting and rolling complex plant of JSC Vyksa Metallurgical Plant, thus increasing the CMM productivity.

Porous plastics are used in various fields of industry, including radio- and electrotechnical fields. They are characterized by good heat- and sound isolating, dielectric and mechanical properties as well as by resistance to effect of various external factors during operation. The problem of estimation of effective permittivity of foam-polymer materials with a large volume fraction of pores, in particular, polyepoxide foam materials, has been considered. Two methods for solving it, both based on the matrix have been proposed. In the first method the matrix is considered as a polyepoxide binder, and the cavities filled with gas are taken as inclusions. In the second method the polyepoxide walls, separating cavities, are taken as inclusions, and gas filling cavities is considered as a matrix. To obtain the formulas for calculation, both methods use a generalized singular approximation of the theory of random fields. Based on the obtained expressions, the model calculations of the effective permittivity of a macroscopically isotropic foam material with a polymer binder based on E-20 and the cavities filled with freon, depending on the apparent density of the material, have been made. The calculations in the generalized singular approximations have been carried out for two of its variants: when the matrix was considered as a comparison medium; and, also by the self-consistent method. In the calculations using the second method two variants of the shape of the cells of the material have been considered: a weakly leaked or heavily leaked polyhedron. The calculated dependences obtained by all me-thods have shown the qualitative compliance with the experimental data.

A 3D-printer for working with plastic mineral mixtures is developed, its kinematic scheme and principle of operation are described. The results of experiments on printing simple forms of plastic clay, using a piston-type extruder, are presented. In relation to an additive technology, a list of technological properties of mineral masses is defined The optimal amount of chemical additives has been established, which provides an increase in the uniformity of the raw material mass for printing products from light ceramics.

Electro-optic properties of Ba0.8Sr0.2TiO3 (BST) film with a thickness of 1 μm deposited on the MgO (001) substrate by the rf sputtering have been studied. Structural features of the film were identified by X-ray diffraction method. It was shown, that the BST film exhibited a predominantly linear EO behavior under the applied static electric field, that have been explained according to the strong compressive stresses in the film. The polarization distribution across the gap between the electrodes when electric field is applied was also investigated experimentally and calculated. The linear EO coefficient of Ba0.8Sr0.2TiO3 film with a thickness of 1 μm film was found to be rc = 99.4 p.m./V, that is promising for various EO applications, for example, high performance EO modulator.

Currently the majority of modern electric arc furnaces (EAF) are equipped with bottom eccentric taphole system. This design allows to tap metal from EAF to ladle with the minimum amount of furnace slag, leaving a part of the liquid metal in EAF for subsequent heats (“liquid start”), if this residue is sufficient. In this case, taphole has several disadvantages: - it is not completely excluded that the oxidized furnace slag enters the ladle, especially with a low level of liquid residue in the EAF, the mass of captured slag in the ladle increases; - tapping time is unstable during taphole system campaign and depends on the wear of its constituent refractories; - periodically required to replace taphole refractories, thus it’s necessary to stop EAF. Under the conditions of the casting and rolling complex JSC “Vyksa Steel Works” work has carried out to change shape EAF’s taphole system, which made it possible to reduce the effect of these disadvantages on the efficiency of the EAF.

The ability to control the bandgap in two-dimensional graphene-like semiconductors is an essential task for the development of optoelectronic and nanoelectronic devices. Complex compositions alloys of transition metal dichalcogenides, such as MoxW1-x Se2yS2(1-y), are the most optimal candidates for this purpose. Here we present spectrally selective photodetectors based on such quaternary transition metal dichalcogenides monolayers. It is shown that the spectral selectivity of optical detectors can be changed in a wide range if the composition of these quaternary monolayer transition metal dichalcogenides varies. This effect is directly related to the significant influence of the composition of such two-dimensional semiconductors on their bandgap. A theoretical model for estimation of quaternary transition metal dichalcogenides optical coefficients and optical detectors on their basis is proposed. The optical absorption simulation in created detectors was made, the results of which qualitatively coincided with the detectors performance. Thus, the obtained results can contribute to the development of valleytronics for two-dimensional semiconductor structures.

A procedure for obtaining foam materials based on an epoxide compound is presented, and the characteristic features of the process are considered. The rheological properties are studied, and the effect of the viscosity of the compound on the morphology of the foam materials being formed is found. Results of a study of the physical and mechanical and thermophysical properties of the developed foam materials are presented. The possibility of obtaining foam materials with physicomechanical and thermophysical operational properties controllable in a wide range is shown.

The article considers the rationale for the optimal mineral composition of friction geomodifiers for improving the tribological properties of friction surfaces. The practice of maintenance and repair of automotive equipment can be significantly supplemented by non-traditional tribotechnics for the non-selective restoration of worn-out friction interfaces and prevention of new equipment. The use of friction geomodifiers as an additive to lubricants dramatically changes the friction conditions. (Research purpose) The research purpose is in developing a methodology for selecting the optimal mineral composition for friction geomodifiers to the technologies of maintenance and repair of machinery and equipment. (Materials and methods) The article describes a study of 27 minerals for tribo-compositions using the ii5018 friction machine using the traditional method. (Results and discussion) A statistical analysis of the results of tribo-tests of different mineral compositions was performed to assess the effect of the petrocomposition on the effectiveness of friction geomodifiers...

A stabler ignition and combustion of the premixed air/fuel mixture remains a topic of great interest due to the high demand for effective and efficient propulsion systems in aerospace applications. Extensive experimental studies and numerical simulations have been carried out to understand and develop ignition systems using cold and non-thermal plasma in microwave streamer discharges. Use of sub-critical streamer discharge allows to ignite air/fuel mixture by an external electric field whose intensity is significantly lower than the intensity required to induce air breakdown. Ignition and combustion of air/propane mixture by microwave sub-critical streamer discharge in low- and high-speed flows is studied experimentally. Qualitative (flame structure) and quantitative (size of combustion region, temperature distributions) characteristics of the flame zone are provided for different flow speeds and equivalence fuel/air ratios, and conditions of discharge initiation with metallic microwave vibrator are studied. The streamer discharge makes it possible to create multiple ignition points providing almost instantaneous ignition of entire volume of the mixture. The results show that the sub-critical streamer discharge can potentially be used in various applications providing more rapid and efficient combustion.

The effect of dimethyl sulfoxide on the copolymerization kinetics and reactivity parameters of N-vinyl succinimide has been studied. Based on a comparison of the results obtained for the copolymerization kinetics of N-vinyl succinimide with vinyl acetate and styrene in dimethyl sulfoxide, general tendencies in changing N-vinyl succinimide reactivity are revealed. It is proven that the complexation between monomeric molecules and dimethyl sulfoxide as an electron-donor solvent leads to a decrease in the relative reactivity of N-vinyl succinimide. Changes in the Alfrey–Price Q–e parameters for N-vinyl succinimide in the course of complexation have been analyzed. The reasons for the change in the reactivity of the monomer are revealed.

A method is proposed for predicting the effective thermal conductivity of a matrix composite with several types of spherical inclusions, in the case of contact thermal resistance at the matrix–inclusion boundary. The method is based on generalized effective-field approximation for a inhomogeneous medium containing inclusions that have an outer shell. As an example, calculations are presented for a matrix tribocomposite with two types of inclusions.

The dependence of the noise density in a signal of a fiber-optic towed streamer in a frequency band of 10 Hz–1 kHz on the towing speed in a range of 1 to 5 knots, on the coefficient of relative elongation of its elastic section, its type, and on the type of attachment of the elastic section to the towed body have been studied. In addition, the dependence of the tensile load on the studied streamer on the towing speed is obtained. The experimental data obtained during field tests on the streamer noise level and their analysis are presented. The reduction of the towing noise level when using an elastic section occurred by a factor of up to 3 in a frequency range of 180 to 600 Hz depending on the type of elastic section when attaching it to a strength member of the towed body, and up to 2 in the entire studied frequency range.

The propagation features and critical conditions of low-velocity detonation (LVD) in the high-density charges of finely dispersed ammonium perchlorate (APC) mixtures with combustible and explosive additives are studied. The effect of the relative charge density, the combustible component type, and the ratio of mixture components, including the mixtures strongly enriched with a combustible agent, on the propagation of detonation is considered. It is shown that the dependence of the detonation velocity on the relative charge density in the case of APC mixtures with combustible additives has a plateau-like region, in which the detonation velocity is at a level of 2000 m/s and is practically independent of the density and nature of the combustible component. Moreover, the critical charge density, above which the failure of LVD is observed, is revealed. In the case of ternary mixtures with a liquid explosive (nitromethane) additive, there is no similar dependence, and the detonation velocity monotonically grows with an increase in the relative density. The critical initiation pressures of compositions are also determined within the density range, where the density has no effect on the detonation velocity. The performed studies make it possible to refine the composition and characteristics of high-density mixtures, for which the application of LVD regimes can ensure the creation of efficient explosion-proof impulse devices.

A method is proposed for predicting the effective thermal conductivity of a matrix composite with several types of spherical inclusions with contact thermal resistance at the boundary of the matrix and inclusions. The method is based on a generalized effective-field approximation for an inhomogeneous medium with inclusions with a shell. Model calculations were performed for a matrix tribocomposite with two types of inclusions. Keywords: effective thermal conductivity, contact thermal resistance, composite material, matrix, inclusion with a shell, Maxwell—Garnett approximation, generalized effective-field approximation. alekc_sap@mail.ru

Designs are proposed for use in the automatic quenching of coke hot spots on conveyers and in automatic loading of fine coke in railroad cars.

In this paper we present an experimental study of the electron transport in composite samples based on an insulating matrix of polybenzimidazole with graphite nanoparticles as conducting filler. Based on a qualitative analysis of the temperature dependences of electrical resistance obtained for the samples with different filler concentrations, it was established that the electron transport occurred mostly by tunneling between conducting filler particles, with variable-range hopping conduction taking place at low temperatures.

The processes of phase formation in the Y-Ba-Co-O system doped with scandium are studied in the region of compositions 1:1:4:7. The mechanism of interaction of initial reagents changes with scandium concentration: at low scandium contents, the (Y1−yScy)BaCo4O7+x (R114) doped oxide is formed, similarly to the undoped system, through the YBaCo2O5+x (R112) phase; at significantly higher scandium contents (≥0.2), the role of the intermediate and the competing phase is played by BaCo1−yScyO3−x representing a number of solid solutions which are stable in wide ranges of temperatures and scandium contents. It is shown that scandium in the R114 structure preferably occupies the yttrium position (Y1−yScyBaCo4O7+x), and the maximum degree of substitution is ymax ≈ 0.3–0.35. When yttrium is substituted with a smaller (in terms of ionic radii) scandium atom, the size of the unit cell diminishes nearly isotropically, the maximum change of its volume being 2.0% (from 353.0 A3 to 345.9 A3).

Studies of the influence of vibration impact on the strength of foam-ceramic raw material, produced on the basis of chemically modified natural silicites, are presented. The natural oscillation frequencies of mineral particles are established, taking into account their size, density and ultimate shear stress of raw suspensions. It is shown that the coincidence of the natural and forced oscillations of the particles leads to an increase in the thixotropic effect. Using the technology of a controlled «sol-gel» transition in the structure of raw material, swelling under the influence of vibration load, samples of the material were obtained with a higher-quality macrostructure without the use of binders. Indicators of compressive strength and average density of raw and ceramics are given.

The results of investigations of the complexation of N-vinylsuccinimide (VSI) in monomer–solvent and monomer–monomer systems and the effect of these processes on the kinetics of copolymerization of VSI with monometers of differing reactivity are summarized. Conditions for the synthesis of compositionally homogeneous copolymers were established. Taking into account the electronic structure of VSI and co-components, a mechanism of complexation in VSI–dimethylsulfoxide, VSI–acetic anhydride, and VSI–maleic anhydride systems is proposed. The electron density redistribution in the VSI molecule upon complexation has been quantitatively assessed.

The results of experimental studies on the kinetics of copolymerization of 2-hydroxyethyl methacrylate with acrylic acid in water and propanol are generalized. The effect of the polarity of the medium on the relative activity of monomers and the microstructure of the obtained copolymers is analyzed.

The current-voltage characteristics of various compositions of nonlinear varistor ceramics based on ZnO (ZOC) and SnO2 (TOC) are studied in a wide range of electric current. On the basis of obtained data were determined the parameters that allow finding the coefficients kprs and kprl, which define the protection levels against the switching surge and the lightning surge for surge suppressors on the basis of ZOC and TOC varistors. The lower the value of these coefficients are, the significantly higher the efficiency of surge protection is. A relationship between kprs, kprl, and the effective linear resistivity ρlin limiting the current of intergranular barriers in varistor ceramics are established. It is shown that the values of kprs and kprl increase with increasing ρlin, which value is determined by the bulk resistance of the ceramic grains. The studied TOC compositions have 2-3 times larger values of ρlin and more high values of kprs and kprl than ZOC. ZOC-based varistors with lower kprs and kprl values provide more effective surge protection than TOC-based varistors.

In this review our recent results on the electron-beam domain writing (EBDW) on the nonpolar surfaces of LiNbO3 crystals of different compositions are presented. The obtained results permitted us to relate the main characteristics of domain formation (the domain sizes and velocity Vf of the frontal motion) to the irradiation conditions (the accelerating voltage U of scanning electron microscopy, EB-current I, the inserted charge Q). The domain depth Td is controlled by U via the electron penetration depth; the domain length Ld increases linearly with Q owing to the domain frontal growth by the viscous friction law. In optical waveguides, the matching of the Td value with the waveguide thickness D provides optimal values of the waveguide conversion to the second harmonic

The results of the experimental studies of underwater explosions of ideal and nonideal detonating charges in continuous water and water-containing air bubbles are presented. Charges weighing up to 50 g are exploded in a metal reservoir filled with water. The parameters of the compression waves in the water are recorded. The effect of the directional propagation of the shock wave in the water along the channel filled with air bubbles is shown. The mechanism of nonideal explosions of highly metallized compositions in water, including explosions in a bubble medium, is also discussed.

The effect of the oxidant composition on the detonation parameters of emulsion explosive sensitized by hollow microspheres was studied. It is shown that the replacement of part of ammonium nitrate by metal nitrates leads to a decrease in the detonation velocity at the same density of explosive. Qualitative changes in the structure of the detonation wave reaction zone were not detected. The best correlation between the results of calculations given in the literature and experimental data on the determination of the dependence of the detonation velocity on density obtained in this work is observed when the Becker–Kistiakowsky–Wilson (BKW) equation of state with a set of RDX coefficients is used.

The paper presents the results of thermal vacuum testing of space technology components and instruments using local helium cryo-panels (“shrouds”) in a liquid nitrogen thermal vacuum chamber. A structural description of prototypes and upgraded helium shrouds is given. The results of experimental layouts at the helium temperature level are presented.

—The productivity of rolling and pipe-rolling mills and the product quality may be improved by heating the metal billet in furnaces with minimum oxidation and decarburization. That is possible in annular furnaces, which are widely used in the rolling of pipe and railroad wheels. High-quality heating permits the creation of metal structure with specified thermophysical and operational properties, as well as the plasticity required for subsequent machining. In the present work, the operation of an annular furnace used to heat pipe blanks before rolling at PAO Chelyabinskii Trubokatnyi Zavod (ChTPZ) is analyzed. Thermal problems are considered: in particular, the high fuel consumption in heating blanks and high external temperatures of the walls and roof; the low rate of blank heating; and the serious leakage of air into the furnace’s working space. In addition, a defect of the gas-burner design is that the gas supply cannot be regulated, despite the wide load range (including periodic shutdown). Finally, practically no use is made of the thermal energy in the exhaust gases. In the analysis of these problems, the heating of the metal is calculated, and the thermal balance of the annular furnace is formulated. The analysis reveals factors that decrease the energy efficiency of the existing furnace design. Measures are proposed for furnace modernization so as to decrease the fuel productivity and increase the productivity: for example, the use of fiber refractories; regenerator burners; and barriers that are not water-cooled. To assess the effectiveness of these measures, we formulate the thermal balance of the redesigned annular furnace and analyze its thermal operation. The proposed measures are expected to provide significant economic benefit and to improve the heating of the metal, with decrease in fuel consumption and increase in productivity. In particular, after reconstruction, increase in the furnace’s total efficiency (by 18.1%) and thermal efficiency (by 31.0%) is expected, as well as decrease in fuel consumption by 48.3 kg CF/t.

The tribotechnical properties of unfilled and dispersed-filled epoxy polymers were studied. The coefficients of sliding friction and the wear rates of polymer composite materials were determined. The dependence of coefficient of sliding friction on type of filler and its content in the polymer composition was studied. The fabricated composite materials were tested for abrasion resistance against steel.

High productivity of rolling and pipe rolling mills, good quality of finished metal products is possible to provide in the presence of powerful heating furnaces, well heating the metal with minimal oxidation and decarburization. Such conditions are provided by ring furnaces which are widely used for heating the preparations at rolling of pipes, wheels and bands of the railway rolling stock. The purpose of the heat – receiving structure of the metal, providing a set of physical and working properties, or impart to these materials the ductility required for subsequent machining. The article deals with the design and thermal performance of the ring furnace operating at ChelPipe’s Pipe Rolling Plant No.2. The problems arising during the operation of the thermal unit are analyzed. The paper describes the calculation of heating of metal and heat balance of the ring furnace. In the course of the analysis of the results of design studies, the shortcomings of the existing heat recovery system are revealed and measures for the reconstruction of the furnace to reduce fuel consumption and increase productivity (replacement of the existing brick lining with fibrous, the use of regenerative burners, the use of non-water-cooled partitions, etc.) are proposed. The paper analyzes the design and thermal performance of the ring furnace for heating of pipe billets before rolling. It shows a heat balance of the ring heating furnace and provides measures for furnace reconstruction aimed at reduction in fuel consumption and increase in efficiency: replacement of the existing lining with fiber lining, use of regenerative burners, application of non-water cooled walls.

In the report the scheme and features of thermal work of the chamber furnace of drum type for heating of metal products under hardening are presented. The technical characteristics of the furnace, some results of thermal calculation are shown. Computer simulation of gas motion and heat exchange processes in the furnace are presented. The study was performed using CAE-system (CAE, Computer aided Engineering) – software module ANSYS Fluent. Boundary conditions of flow flow flow were set in this module. To verify the convergence of the calculations, the control of the current values and calculated temperature residuals was used. The simulation results are presented graphically and contain a visualization of the temperature and velocity distribution fields, as well as a vector distribution of gas flow velocities. The obtained results of computer simulation allowed to estimate the efficiency of thermal and gas-dynamic work of the developed design of the chamber drum-type furnace with a constant temperature of the working space. The developed design of the furnace for heating metal billets with the movement of billets in the furnace on the drum allows to solve some problems of resource and energy saving, can also be used for heat treatment of bars, pipes, strips, and rolled bars of various shapes.

Here we present the results of the exciton states study in WSe2 and MoS2 monolayers. Thin WSe2 and MoS2 films obtained by CVD technique were studied by optical methods. The films two-dimensionality and homogeneity were confirmed by the methods of atomic force microscopy and luminescence spectroscopy. The second harmonic generation (SHG) spectroscopy technique was used for the exciton states study at room temperature in the pump photon energy range of 0.8-1.05 eV. The sevenfold SHG intensity resonance amplification was found for the 1.62 eV and 1.87 eV SHG photon energy for the WSe2 and MoS2 films, respectively, that corresponds to the exciton transition energy. These resonance peaks belong to optical A excitons with 1s energy level.

By means of a generalized effective-field approximation, formulas are derived for the effective thermal conductivity of a three-component tribocomposite based on a phenylone matrix with spherical strengthening inclusions (alumoborosilicate glass) and inhomogeneous antifrictional inclusions (spherical capsules of glycerin in a Kapton® shell). The thermal conductivity is investigated as a function of the concentrations of inclusions and the ratio of the internal and external radii of the antifrictional inclusions.

Bonding between cement and steel is currently believed to be of key importance in well integrity since it prevents the development of microannulus. Push-out test is often used to quantify the bonding strength between cement and steel in laboratory. Our experiments reveal a strong size-dependency of the push-out strength measured in these tests: the strength decreases with pipe diameter. This means that the push-out strength is not an intrinsic material parameter ("bonding strength") and therefore cannot be applied to field conditions before a proper correction is introduced. Such correction should take into account the large difference in diameter between the casing and the pipes typically used in laboratory tests. Finite-element simulations show that the experimentally-observed size-dependency could be, at least partially, explained by cement shrinkage that creates initial normal stress at the interface. The observed push-out strength is then not an intrinsic property of the interface between two materials (which would be an adhesive shear strength) but rather a result of interfacial friction. As the pipe diameter increases, the shrinkage-induced normal stress at the interface decreases, the frictional resistance decreases, and thus the measured push-out strength decreases, too, as observed in the lab tests. Simulations show, however, that shrinkage-induced decrease in push-out strength cannot fully explain the size-dependency since the decrease is much larger in the experiments than in the simulations. Another mechanism that could be at play is the common size effect: interfaces become weaker as their size increases because it is more likely that a larger interface contains an initial flaw of a given size. The decrease of push-out strength with pipe diameter has at least two practical implications: (i) the concept of bonding strength is misleading (unless it is specified explicitly that this parameter refers to frictional resistance at the interface rather than to an inherent adhesive strength) and (ii) the results of push-out tests can be used in well design only if a proper correction for the pipe diameter is introduced.

Thermovacuum tests of space technology samples using local cryo-screens cooled by liquid He in a thermobarochamber are reported. The constructions of the prototypes and manufactured He cryo-screens are described. Experimental results are given for test models(.) Application features of local cryo-screens cooled by liquid He that were found during the research are discussed.

The results of experimental studies on copolymerization kinetics of 2-hydroxyethyl methacrylate with carboxyl-containing monomers of acrylic, methacrylic, and maleic acids in water using the redox initiator system of ammonium persulfate–ascorbic acid are summarized. The effect of process conditions on the reaction rate, relative activity of monomers, composition, and microstructure of copolymers is analyzed.

A polymeric compound of poly(N-vinyl succinamic acid) and poly(vinyl alcohol) is obtained by conducting the polymerization of N-vinyl succinimide and reactions in the chains of its polymer in the presence of poly(vinyl alcohol). The possibility for the intermolecular acetalization and structuring of the (co)polymers of vinyl alcohol containing ionic units of N-vinyl succinamic acid with the use of glutaric aldehyde is determined. The swelling and moisture absorption of the structured (co)polymers and their ability to sorb low-molecular-weight biologically active substances with their prolonged release is studied.