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The surface layer of an obstacle made of U8 steel is investigated after high-speed exposure to a flow of powder particles. After analyzing the frames of high-speed photography, the average velocities of movement of particles of tungsten and titanium carbide powders were determined. It is shown that the shock-wave loading of the barrier material and the effect of particles accelerated by the explosion energy provide a change in the physical and mechanical properties of the surface and the volume of the steel barrier material.

This work is devoted to studying the structural and morphological properties of a silver colloidal solution obtained by the method of electrical-spark discharge in distilled water. Silver nanoparticles are formed as a result of metal sputtering from the surfaces of silver electrodes, between which a high-voltage electric discharge is generated. The solution is stabilized by forming a layer of anions around the nanoparticles. The structural characteristics of the colloidal solution are studied by small-angle X-ray scattering and transmission electron microscopy. The ionic composition is determined qualitatively using electrospray ionization mass spectrometry, while silver concentration is measured by inductively coupled plasma atomic emission spectrometry.

Two variants of gene-activated hydrogels based on sodium alginate containing plasmid DNA with the gene of vascular endothelial growth factor (VEGF-A) are developed. The former represented alginate hydrogel without additional components; the latter contained up to 25 wt % of octacalcium phosphate (OCP) micrograins. Alginate-based hydrogels without OCP are characterized by a honeycomb structure with the pore size of 50–200 μm and mechanical compression strength of 0.2 MPa. Addition of OCP micrograins results in filling of the polymer framework by them and an increase in the compression strength to 0.57 MPa at 16.7 wt % of OCP with a decrease to 0.49 MPa with an increase in the OCP content to 20 wt %. Both variants of gene-activated hydrogels induce reparative myogenesis in the central zone of muscle defect; a larger number of MyoG+ cells and newly formed MyH7B+ muscle fibers are identified as compared to analogous hydrogels without plasmid DNA after two weeks after surgery (p < 0.05).

The issue presents the results of studies of methods for increasing the corrosion resistance of fuel claddings made from zirconium alloy E110, performed at the SRC RF TRINITI, using coatings (Al, Al2O3, Cr) by pulsed laser deposition, as well as magnetron sputtering and galvanic deposition of chromium. Also presented some results of studies of adhesion, microstructure and corrosion resistance of chromium coatings deposited by various methods. It was revealed that the corrosion resistance of the cladding of fuel rods with chrome coatings at temperatures of 1100 – 1200 °С practically does not depend on the method of their application. However, the coating method has a significant effect on their adhesion, with coatings obtained by atomic deposition methods and characterized by a continuous uniform structure have the greatest adhesion. The depth of oxidation of the outer surface of the cladding of a fuel rod when applying a chromium coating decreases by an average of 30 times for sponge-based alloy E110.

The presented system for the theoretical and experimental evaluation of images obtained in a holographic microscope can be directly used for the diagnostics of industrial products during the manufacturing process. It is found that controlling the positioning of the cathode–research object in a holographic microscope can be effectively carried out by monitoring the substrate current. The resolution of the coordinate-sensitive detector of the microscope is calculated to be 400−0.4 nm. It is shown that continuous monitoring of the conditions of experimental research is necessary to obtain an informative image because each object under study is essentially unique. Test studies of thin aluminum films are performed.

Experiments were conducted on high-energy surface treatment of a structural steel substrate with a flow of tungsten, nickel, and titanium nitride powder particles. The impact pressure of the steel target and particles accelerated by explosion energy was estimated using the momentum conservation equation and the linear equation of the particle material shock adiabat. It was found that the impact pressure of the target and particles is 62 GPa for a tungsten particle, 48 GPa for a nickel particle, and 41 GPa for a titanium nitride particle. The heating temperature of particles during their collision with the steel target surface was calculated taking into account the conditions of mass and momentum conservation at the shock wave front. The maximum heating temperature of particles at the point of their collision with the substrate surface (at a particle velocity of 2000 m/s) is 1103 K for tungsten particles, 755 K for nickel particles, and 589 K for titanium nitride particles. It was shown that the steel target strength increases when it is subjected to high-energy treatment with a flow of particles. The maximum hardening of the steel target surface layer increases by 32–55 % compared to initial microhardness and is observed at a depth of 2–4 mm from the treatment surface. Then it decreases to the value of starting material microhardness (170 HV) at a distance of 15–20 mm from the treated surface.

The technology for producing metallized coatings on superporous carbon fiber materials from colloidal solutions by means of electrophoresis is studied. Technologies and equipment for the deposition of silver nanoparticles and other metal nanoparticles on rolled carbon materials are considered. The carbon materials consist of fibers 6 μm thick and are used as an electrode materials for current sources.

A vacuum holographic microscope is designed to probe the atomic structure of thin metal films. The experimental setup is based on the use of a source of a monochromatic low-energy electron beam induced by a tip cathode spaced from the sample at a distance of several tens of nanometers. The visual resolution of atoms of the object requires a microscope magnification of at least 105, which necessitates high-accuracy movement of the electron source. The parameters of principal nodes of the microscope, which are responsible for the generation and recording of useful signals, are studied and optimized, as well.

Measurements of field emission energy distribution (FEED) by the retarding potential method have been performed for electron emission from the top of mono crystal macroemitter, made by the sublimation method, N doped (n-type) on 4 deg. off 4H-SiC wafers (0001-C). A peculiar feature, revealed from the FEED patterns is the existence of two maxima.

Today LED lamps are used more and more widely in various fields of human activity. The operation of LEDs substantially depends on the thermal dissipation power and temperature. In this regard, one of the mandatory stages in the process of creating such lamps is the analysis of their thermal mode, which is necessary for the development of a heat sink. In order to analyze the thermal mode and design the heat sink for powerful LED lamps, the authors synthesized the structure of the problem solver. The new structure was based on the structure of the basic laplacianFoam solver and the application of the swak4foam library functions, which is a part of the OpenFOAM computational fluid dynamics toolbox. The results of the thermal mode simulation of the LED thermal model (a plate with a rectangular heat source) obtained using a modified solver were compared with those obtained by the proprietary solver of the CAD/CAE SolidWorks system and those obtained by analytical computation. The data adequacy of the modified solver was estimated and its practical application verified. The thermal mode of the Samsung LC009D LED, which is placed on the flat-plate finned heat sink, was analyzed. The Kaufer 5204 glue ability to be used in such design with natural convection cooling of the heat sink was tested. The glue thickness was 0.1 mm and its thermal conductivity was 1,5 W/(m•К). The heat sink’s heat transfer coefficient was 10 W/(м2•К). The paper presents corresponding temperature distributions and shows that the new technique can be used for solving problems that arise when designing LED lamps

One of the final stages of microprocessor development is thermal testing. This procedure is performed on a special stand, the main element of which is a switching PCB with mounted microprocessor sockets, chipsets, interfaces, jumpers and other components which provide various modes of microprocessor operation. Changing the case temperature of the microprocessor is carried out typically using a thermoelectric module. The cold surface of the module with controlled temperature is in direct thermal contact with the microprocessor housing designed for cooler installation. On the hot surface of the module, the radiator is mounted which dissipates the total heat flux from the microprocessor and the module. High density PCB layout, the requirement of free access to the jumpers and interfaces, and the presence of numerous sensors restrict the space for radiator mounting and require the use of an extremely compact radiator, especially in air cooling conditions. One of possible solutions for this problem may be to reduce the area of the heat-transfer surfaces of the radiator due to a sharp growth of the heat transfer coefficient without increasing the air flow rate. A sharp growth of heat transfer coefficient of the radiator can be achieved by making several conic or combined conic-cylindrical dead-end cavities with extra finning in the heat-transfer surface. Such cavities should absorb the impact air jets. In this study, CFD simulation of such radiators has been conducted. It is determined that when the air velocity at the nozzle entrances is 50—100 m/s, the investigated designs of impact-jet radiators have a thermal resistance in the range of 0.5—2.2°Ñ/W. This is quite sufficient for the thermal testing of some types of microprocessors with setting a number of operational modes and performing of certain types of test computations. It is shown that the use of combined dead-end cavities with extra finning is the best of the considered solutions and allows for a sharp (up to 44%) intensification of heat transfer in the radiator in comparison with cylindrical dead-end cavities, but at a cost — the loss of air pressure increases up to 20%. As a result of the study, it was found that the impact-jet radiator with dead-end tapering cone shaped cavities and combined cone-cylinder shaped cavities with extra finning, can successfully solve the problem of heat removal from microprocessors during thermal testing. However, it should be noted, that such radiators have a high aerodynamic resistance and require a high pressure air source for operation.

The deficiencies of existing standard iron and nickel samples for calibration by means of X-ray diffraction are noted. These standards cannot be used in calibration by magnetic noise recording. A new calibration method based on X-ray diffraction is proposed, using plane samples of the material employed in the manufacture of the actual structures. Theoretical analysis provides the basis for the development of null standards in which a plane sample is deformed by pure flexure or in a cantilever-beam configuration.

A procedure and a setup for determining the spatial distribution of the concentration of droplets in a spray cone formed as a result of liquid dispersion by sprayers are described. The proposed procedure is based on measurement of the spectral coefficient of spray cone transmission during laser scanning over the chords of the different sections of the spray cone with subsequent solution of the corresponding inverse problem (of Abel′s equation). The characteristics of the structure of the spray cones obtained with the use of ejective and centrifugal sprayers are given.

The existing excimer lasers with pulse durations in the nanosecond range and high pulse and average power afford a unique possibility of influencing the surface of materials and developing new, efficient technologies. It is shown in this article that surface treatment with a periodic-pulse UV laser cleans surfaces by removing oxides, reduces roughness, and increases hardness. Different variants of pulsed laser deposition of aluminum and Al2O3 are used to form protective, composite, cermet layers that suppress surface corrosion of EP-823 steel fuel-element cladding in lead in contact with air at 650–720°C.

The created experimental magnetron sputtering system allows preliminary cleaning of the substrate surface and subsequent deposition of coatings on long cylindrical products within a single system using a coaxial magnetron discharge at a working gas pressure of 150 mTorr. The coating discharge has reverse electrodes polarity relative to the cleaning discharge. A theoretical calculation of the discharge parameters has been carried out.

A calibration technique for cryogenic temperature sensors is proposed and implemented. The experimental setup is based on the helium cryogenerator, providing calibration of the temperature sensors of various types in wide temperature range, including cryogenic band (25-100K). A condensation thermometer with hydrogen, neon, argon and xenon as working gases is used as a reference sensor. The experimental setup was successfully used for precise (0.1K precision) calibration of platinum resistive temperature detectors (Pt-100) for international nuclear physics experiments MuSun and PolFusion. The setup can also be used for calibration of temperature sensors of the other types.

Suggested is a new explanation for the phenomenon of superdeep penetration of shock-accelerated particles into solid targets in terms of the so-called barodiffusion mechanism. The suggested concept of barodiffusion mechanism opens up new horizons for further studies in the field under consideration.

The authors consider the possibility of intensification of heat transfer in fluid heat exchangers with cavity-pin finning by changing the shape of the cavities. It is shown that the transition from circular to elliptic cavities leads not only to a significant intensification of heat transfer but also reduces the size and weight of the heat exchanger.

In this paper the application technology of the ultrasonic testing method in the process of the PS-90A aircraft engine manufacturing is considered. It is known that the development and implementation of monocrystalline turbine blades for aircraft gas turbine engines are aimed at ensuring the material effectiveness or increasing the blade service life in comparison with polycrystalline blades. It is achieved at the cost of the increased long-term material strength in the same temperature range. Based on the results of the process and metallographic studies analysis, it has been established that during the structure formation under the internal stress action, hot crystallization cracks with an opening from 3 to 8 μm or more and a length of 3 to 35 mm along the grain boundaries can appear. Grains formation in most blades happens with their subsequent exit to the lock end, a bridge. The formation of hot cracks most likely occurs at a large grain disorientation angle (more than 25°). Grain boundaries on blades with hot crystallization cracks are located, as a rule, on the bridge at the junction of the blade root with the blade shank (“bottleneck”) with orientation along the blade axis. The method of contact laser-ultrasonic flaw detection (CLUFD) was tested on blades in the region of bridges using both pilot samples and standard parts in order to solve an urgent production and technical problem, that is timely detection of hot crystallization cracks in rotating turbine engine blades at the manufacturing stage. The use of the phased antenna array technology (PAR) in combination with a portable X-32 flaw detector represents a new level of blade ultrasonic testing. The flaw detector operates in a wide frequency range, which allows solving a very large range of various ultrasonic testing problems. The advantages and possibilities of the PAR technology with the portable X-32 flaw detector can be considered on the example of the turbine blade lock testing. S-scan (sector-scan) makes it possible to interpret the received signals quickly and easily.

The features of the total energy distribution of electrons emitted from highly oriented pyrolytic graphite, multiwall CNT and graphene-like structure were studied experimentally by the retard potential method. It was established that in all cases there is a noticeable shift of the maximum of the energy spectrum relative to the Fermi level. The appearance of the second maximum, which is shifted from the main peak by 2 – 2.5 eV, was also found out. The half-width of the distribution is broadened in both cases when electric field increases

One of the final stages of microprocessors development is heat test. This procedure is performed on a special stand, the main element of which is the switching PCB with one or more mounted microprocessor sockets, chipsets, interfaces, jumpers and other components which provide various modes of microprocessor operation. The temperature of microprocessor housing is typically changed using thermoelectric module. The cold surface of the module with controlled temperature is in direct thermal contact with the microprocessor housing designed for cooler installation. On the hot surface of the module a radiator is mounted. The radiator dissipates the cumulative heat flow from both the microprocessor and the module. High density PCB layout, the requirement of free access to the jumpers and interfaces, and the presence of numerous sensors limit the space for radiator mounting and require the use of an extremely compact radiator, especially in air cooling conditions. One of the possible solutions for this problem may reduce the area of the radiator heat-transfer surfaces due to a sharp growth of the heat transfer coefficient without increasing the air flow rate. To ensure a sharp growth of heat transfer coefficient on the heat-transfer surface one should make in the surface one or more dead-end cavities into which the impact air jets would flow. CFD simulation of this type of radiator has been conducted. The heat-aerodynamic characteristics and design recommendations for removing heat from microprocessors in a limited space have been determined.

It is demonstrated that the field emission from graphene-like structures (GLSs) has a very low excitation threshold (about two orders of magnitude lower than that of metals and semiconductors). It is shown that the total energy distribution (TED) of field emission electrons from GLSs differs considerably from the spectra obtained for metals. The existence of two maxima of this distribution (spaced 0.7–1.7 eV apart), significant broadening of the energy distribution, and a shift of these maxima depending on the electric field intensity are reported. The resonance nature of low-threshold field emission from GLSs is confirmed.

The work is devoted to the study of the influence of the parameters of ultrasonic shot peening on the physicomechanical properties of the surface layer of flat samples of 08ps steel, AMg2 and M2 alloys. The results of determination of residual stresses, microhardness are given. As a result, it was established that the processing time makes the largest contribution in the selected modes.

The high-velocity impact of a tungsten particle flux with the surface layer of steel (U8) samples is studied. High-speed photography which was used to record the motion of tungsten particles and detonation products shows that tungsten particles move with an average velocity of 2.4 km/s. Microstructure studies have revealed that upon the impact of tungsten particles with the surface of the target, the temperature in the active zone exceeds the temperature of the peritectoid reaction in the Fe-W system, and the polymorphic transformation of iron takes place with the formation of austenite and the dissolution of tungsten carbide in austenite under these temperature conditions.

Combustion synthesis of ZnS from Zn-S powder mixtures in a closed volume was found to equally readily proceed in a mode of deflagration or detonation. We have also found that Zn-S mixture represents a specific explosive whose brisance is close to that of high explosives but the fougasseness is exceedingly low. This mixture can be recommended for use in applications requiring short and strong impact on materials without destructive damage of the environment.

A helium-3 adsorption refrigerator cooled with a pulse-tube cryocooler is developed. The refrigerator has two stages of adsorption pumping. The first stage is designed for the condensing and pumping of helium-4, whose cooling capacity is used for the condensation of helium-3. The second stage is designed for pumping helium-3. The final temperature reached by the refrigerator is 0.305 K. This temperature is retained for at least 24 h. The time required for helium recondensation and the obtainment of low temperature is 1.5 h. The cryostat is a self-contained instrument, as it contains no external gas-supply pipelines and the working gas is stored directly within the working volume of the refrigerator. The work is performed in the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research.

Analytical expressions for the calculation of drawing stress and the optimal channel angle of the drawing tool, making it possible to operatively evaluate the influence of various manufacturing factors on the energy-power parameters of the process and on the longitudinal stresses in the layers of bimetallic composite, are derived for designing the drawing process of bimetallic wares. Disadvantages of the proposed formulas are noted.

When designing the drawing process of sections with a regular polygon profile, it is convenient to use analytical expressions that make it possible to operatively evaluate the effect of different manufacturing factors. A calculation procedure for stress in this process is proposed. The relationships are derived for the calculation of the drawing stress, the optimal angle for the drawing-tool channel, the limiting deformation rate with the use of a standard tool, and the stress-state characteristic in the axial part of the deformation zone. The application of a drawing tool with optimum angles decreases the accumulation rate for defects of the metal structure and makes it possible to decrease the number of intermediate thermal treatments during multiple drawing.

The results of an experimental study of drop motion and breakdown in a swirling flow of a viscous liquid at small Reynolds numbers are presented. It is shown for the first time that the drop breakdown is observed at some critical values of the Bond number at small Reynolds numbers. The dependence of the critical Bond number, corresponding to drop shape instability by the Rayleigh-Taylor mechanism, on drop motion regime at Reynolds numbers Re = 0.03–0.84 is experimentally found.

We describe specific features of an optical-fiber-based method of remote identification of the type of material and demonstrate the possibility of determining the main types of building materials from spectrograms of a plasma plume produced by a laser beam acting upon a material surface.

Composite materials for biomedical applications based on polylactide, a bioresorbable polymer, and nanosized calcium phosphate (hydroxyapatite) were produced using supercritical (SC) carbon dioxide. For composites with different polymer-to-mineral ratios, the bending stress-strain diagrams were investigated. The elasticity moduli of composites obtained in SC-CO2 from powdered bioresorbable polymer and bioactive nanoceramics ranged elastic modulus of natural bone. Experiments on adhesion of human embryonic fibroblasts demonstrated the suitability of generated samples for use in bone tissue scaffold engineering and regenerative medicine.

A holographic microscope is intended for investigation and visual observation of nanoobjects that are thin metal films or macromolecules. A module providing for the experimental research of such objects has been designed and built. The optimal thickness of the metal films has been estimated. Software for processing the interference patterns with the aim of obtaining a holographic image of nanoobjects has been developed.

In this work, the main parameters of a holographic microscope are studied with the aim of optimizing them. The optimum positions for the monochromatic electron-beam source with respect to the subject of research and for the screen detecting the interference pattern (the distance is 100 nm and 10 cm, respectively) are determined. The limiting thickness of the thin film of the subject of study (30 A) at which the interference pattern can be observed is estimated. The main parameters of the coordinate-sensitive detector providing signal gain up to 105 at the output are calculated.

We study the defects of a flap actuator of the wing of an An-124 aircraft. The fractographic and metallographic investigations of the surface defects of a screw-nut friction couple are performed. A device for wear tests under the conditions of fretting corrosion is developed. Recommendations concerning the reduction of possible damage to flap actuators are proposed.

A method is proposed for determining permeability of coals under conditions of steady-state deformation and stationary filtration mode by employing a reference core made of gas-non-sorbing material with a known permeability. The approach has been developed to assess the time of transition to the stable filtration.

The design of a compact ultrahigh-vacuum nitrogen-free helium cryostat is described. The volume of the helium vessel of the cryostat is 2.7 l, and the time of operation after filling it with liquid helium is >65 h. The cryostat satisfies the requirements imposed on ultrahigh-vacuum systems, allows heating to 200°C, and ensures operation at an evacuation level of 10−10 Torr.

In this paper original technology of electrode production with track membrane materials for electrical neurostimulation is described. Presented results show that the technology allows one to produce conducting structures with gas-and water-permeability in places of unfilled pores by metal. The created electrodes also have antiseptic properties.

Time differential perturbed angular gamma-gamma-correlation (TDPAC) method on 111Cd nuclei probes inserted in ZrZn1.9 is used to measure the magnetic hyperfine fields (MHF) at Zr and Zn sites and the electric field gradient (EFG) Vzz at Zn sites as a function of temperature at various pressures and as a function of pressure at the temperature 4 K. Our data indicate that the local magnetic moment of Zr in the magnetically ordered state is substantially larger than its value obtained from the macroscopic measurements and that there is also an induced magnetic moment at the Zn site. We conclude that ZrZn2 is not a simple ferromagnet and discuss a possible type of its magnetic ordering., 7 pages, 6 figures, submitted for publication

Polycrystalline and nanocrystalline samples of the CuCr2Se4 ferromagnetic spinel are synthesized. The mean size of nanocrystals is 50 nm. The Curie temperature of spinel nanocrystals (465 K) is higher than that of spinel polycrystals (435 K). Laser irradiation at a wavelength of 1.5 μm (in an external magnetic field) increases the magnetization of the noncrystalline powder. Most likely, this can be explained by the change in the orientation of magnetic moments of single-domain nanoparticles. The observed effect reaches a maximum in magnetic fields with a strength lower than that of the saturation field.

The possibility of local buckling of the free surface of the lower half-plane under compression is studied in a static formulation within the framework of plane deformation. It is shown that in some media small subcritical strains can lead to local buckling of the half-plane surface. It is found that two forms of local surface buckling correspond to one critical compression load.

A physicomathematical model and results of numerical studies of aerodynamics and combustion of liquid fuel in a coaxial swirling flow of a gaseous oxidizer are presented. The characteristics of liquid-fuel spraying by a centrifugal injector were determined on the basis of experimental data obtained under isothermal conditions. The influence of flow swirling on the burner characteristics is analyzed.

The profile of an atomic beam in the region where it forms is an important characteristic of a polar- ized atomic hydrogen (or deuterium) source. A mathematical model for a two-coordinate resistive detector of atomic hydrogen beams is presented. Metering equipment and a technique for measuring an atomic beam pro- file are described, and the results of our measurements are presented.

This paper reports results from experimental studies of the formation of secondary drops during impact interaction of a drop with a liquid surface. The experimental data are compared with analytical estimates of the parameters of the cavern formed and the Rayleigh column.