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Sodium liquid glass silicate compositions modified with boron cluster anions [B10Cl10]2− or [B10H10]2− or SiO2 nanoparticles have been studied. It is shown that in the silicate matrix, the presence of the polyhedral anions results in nanoscale supramolecular structures formed due to their interaction with silanol groups of silicates. In the range of 20–600 °C, the TMA method is used to study the formation of supramolecular associates, as well as the deformation stability of the modified silicate matrix and the softening temperature of the modified polysilicates formed upon thermal exposure. Resumen: Se han estudiado composiciones de silicato de vidrio líquido de sodio modificadas con aniones poliédricos [B10Cl10]2− o [B10H10]2− o nanopartículas de SiO2. Se muestra que en la matriz de silicato, la presencia de los aniones poliédricos da como resultado estructuras supramoleculares a nanoescala formadas debido a su interacción con grupos de silicatos de silanol. En el rango de 20–600 °C, TMA se ha utilizado para estudiar la formación de asociados supramoleculares, así como la estabilidad a la deformación de la matriz de silicato modificado y la temperatura de reblandecimiento de los polisilicatos modificados formados tras la exposición térmica.

Studies were carried out in this work to establish the influence of thermal cyclic and mechanical cyclic loads that simulated the factors of operational impact on structural stability and crystal lattice dilatation of zirconium alloys. It is shown that during cold cyclic deformation at the first moment of loading the Zr–2.5Nb alloy is characterized by significant instantaneous deformation. The effect of anomalous thermal deformations of the zirconium alloy crystal lattices, which are typical for phase transitions of type I and type II, was detected in the operating temperature range (250–350 °C). The absence of phase transformation in this temperature range allows us to suggest the existence of a causal relationship between the anomalous thermal expansion effects of zirconium crystal lattices with orientation changes and phase transformations in grain boundaries. The performed calculations showed the presence of an anomalous change in the crystallite size distribution at a given temperature. The coincidence that temperatures were correlated with size effects and phenomena such as blistering and flecking has been established. The hypothesis of grain-boundary transformations is indirectly confirmed by the results of the second thermal cycle, during which a second jump of the crystal lattice thermal deformations, not related to structural phase transitions, was detected in the range of 550–650 °C.

Reservoirs-coolers are a typical component of technological schemes of large energy complexes. Thus, it is important to maximize the efficiency of their exploitation. The present paper discusses the possibilities of the increase in the efficiency of reservoir-cooler usage on the example of the Magnitogorsk Iron and Steel Works (further, PJSC “MMK”), which produces the greatest amount of rolled steel on one industrial site. A reservoir-cooler created on the basis of the Magnitogorsk Reservoir of Ural river is considered. The schemes for the location of the enclosing and diverting dams is suggested on the basis of hydrodynamic modeling in a 2D approach. The calculations are performed for different scenarios where both extreme climatic and technological conditions and the ones characterized by the highest repeatability are considered. To increase the stability of the reservoir-cooler functioning in a short periods of extremely high air temperatures, the scheme of the organization of selective water intake from the deep layers of the reservoir-cooler characterized by lower temperatures is worked out on the basis of hydrodynamic modelling in 3D approach.

The effect of acoustic wave propagating in the direction of temperature gradient on a stability of stationary plane-parallel flow of binary fluid, generated by horizontal temperature and concentration gradients in a horizontal layer is investigated for two types of thermal boundary conditions: perfectly conductive and adiabatic boundaries. The study is performed analytically for the longwave perturbations and numerically for finite-wavelength perturbations. Stability maps for fixed Prandtl number value Pr = 0.01 and different values of Schmidt number and acoustic Reynolds number are obtained. The most dangerous instability modes and critical perturbation structure are discussed. Comparison with the case where acoustic wave is absent is performed. It is shown, that longwave perturbations are always stabilized by acoustic wave. Numerical investigation demonstrates, that acoustic wave also stabilizes the flow with respect to finite-wavelength perturbations when negative concentrational Grashof number is higher in modulus than certain value depending on acoustic wave intensity.

In this paper we investigate a linear stability of quasi-equilibrium states and supercritical regimes of thermal vibrational convection of a Williamson fluid between two rigid parallel plates, maintained at constant different temperatures in zero gravity conditions. Calculations are made for different angles of inclination of the vibration axis relative to the layer. It has been found that, as in the case of a Newtonian fluid, most dangerous are the hydrodynamic monotonic perturbations. Enhancement of viscoplastic properties of a fluid has a destabilizing effect at all angles of inclination of the vibration axis. An increase in the Prandtl number stabilizes the quasi-equilibrium states of the pseudoplastic fluids. In the viscoplastic limit, the critical value of the modified Rayleigh number, which determines the quasi-equilibrium stability threshold, does not depend on the Prandtl number and rheological parameters. The critical value of the perturbation wave number for pseudo- and viscoplastic fluids depends only on the angle of inclination of the vibration axis. The type of the convection excitation and the structure of the supercritical convective flows under longitudinal vibrations have been studied on the basis of full nonlinear equations of thermal vibrational convection. It has been found that the supercritical bifurcation takes place.

The work is devoted to studying the excitation of the Rayleigh-Benard-Marangoni convection in a two-layer system of immiscible fluids with a deformable interface and rigid perfectly heat-conductive external boundaries. The influence of thermocapillary effect on the linear stability of the conductive state of the system under vertical temperature gradient is analyzed. The problem is solved in the framework of the generalized Boussinesq approximation, which allows us to correctly take into account the deformations of the interface. It has been found that, depending on the properties of fluids, a thermocapillary effect can either stabilize or destabilize the longwave mode of instability associated with the deformations of the interface. In the case of a two-layer system of formic acid and transformer oil, strong destabilization takes place. Numerical calculations performed for this pair of fluids at arbitrary values of wave number have shown that the influence of thermocapillary effect on finite-wavelength monotonic and oscillatory instability modes is also destabilizing. However, the lowering of instability threshold to oscillatory finite-wavelength perturbations due to the thermocapillary effect is much weaker than that for both longwave and finite-wavelength monotonic instability modes. As the result, at sufficiently large values of the Marangoni number the conductive state becomes unstable only with respect to monotonic perturbations. Further enhancement of the thermocapillary effect gives rise to a thermocapillary finite-wavelength oscillatory instability mode, which occurs at Galileo numbers large in absolute value ( Ga - 80 ). Good agreement between the results of calculations and available experimental data has been obtained.

The paper is devoted to the investigation of the linear stability of homogeneous pulsating vertical seepage of mixture through horizontal porous layer with solute immobilization. The mixture flow through porous medium is studied within the standard Darcy-Boussinesq approach taking into account the solutal convection. The immobilization of solute particles by solid matrix of medium is described by the mobile/immobile media (MIM) model with second-order kinetics. It was shown earlier that the immobilization leads to oscillatory mode of convective instability due to transition of solute from the mobile phase to immobile one. This means that immobilization effect on the flow pulsations should be non-trivial. The equations for the convection with immobilization are derived, the regime of homogeneous filtration is obtained and its stability is investigated. The neutral curves in the parameter space are plotted. The effect of homogeneous filtration stabilization under intensification of external seepage and dynamics interphase exchange is studied. It is found that the effect of pulsations is significant in the case when frequency of pulsations is close to the natural frequency of instability. The parametric excitation of convection is not observed.

In this paper, we study the effect of vibrations on the stability of a stationary plane-parallel flow of a pseudoplastic fluid in an infinite vertical layer between two rigid perfectly heat conducting boundaries, maintained at different temperatures. It is assumed that the layer performs vertical high-frequency vibrations perpendicular to the imposed temperature gradient. Vibration intensity is characterized by the dimensionless parameter V, typical values of which in the terrestrial conditions vary from 0 to 1. The fluidity of liquid is found to increase with increasing vibration intensity. The stability of a stationary plane-parallel flow with respect to small plane normal-mode perturbations, periodic along the layer, is investigated for Prandtl number values Pr = 1 and Pr = 100. The results show that, for Pr = 1, at any values of rheological parameters under examination, the monotonic hydrodynamic perturbations having a form of immovable vortices at the boundary of counter-current flows are responsible for the instability of a stationary flow. The value of the modified Grashof number, which determines the base flow stability threshold, decreases monotonically as the pseudoplastic properties of fluid become stronger. Vibrations also produce a destabilizing effect. For Pr = 100 there are three instability modes: the monotonic hydrodynamic instability mode and the thermal oscillatory Rayleigh mode, which exist in the absence of vibrations, and the vibrational oscillatory mode. In the case of low-intensity vibrations, the thermal Rayleigh mode is the most dangerous one. An increase in the vibration intensity, vibration mode becomes the most dangerous. The growth of dynamic yield stress leads to a decrease in the value of the vibration parameter V at which the vibrational mode becomes the most dangerous mode.

Thermal pollution of water bodies is an unavoidable consequence of thermal or nuclear power plant operation. To minimize the detrimental effects of these plants, one should assess the nature of dangerous zones. The most effective approach to solving these problems is the computational experiment. This paper presents the results of a numerical study of thermal pollution in one of the largest thermal power plants of Europe - Permskaya TPP, using the Kama Reservoir as a natural cooling system. Such problems are traditionally solved in 2D formulation using the “shallow water” approximation. However, with this approach it is impossible to take into account the vertical inhomogeneity of the temperature field. On the other hand, 3D models, which can take into account the effect of density stratification, require very large computational resources. In this work, a combined approach, based on a combination of computational models in the 1D, 2D and 3D formulations, is applied.

Numerical investigation of flows and heat and mass transfer during the directional solidification of high temperature SiGe alloys in the presence of rotational vibrations has been performed. It has been shown that the structure of a vibration-induced flow has the form of a vortex localized near the crystallization front and the direction of this flow is such that the fluid moves along the front from the symmetry axis to the wall of the crucible. With the increase of the vibration parameter the intensity of the vortex grows, and the concentration gradient on the crystallization front near the crucible wall increases. This causes an increase in the crystallization temperature in this region, the temperature of the melt in this area becomes lower compared to the crystallization temperature, and hence the melt becomes overcooled. For the germanium-silicon system, changes in the gravity force lead to the changes in the flow and heat and mass transfer regimes, which are accompanied by a hysteresis. The analysis of the obtained numerical results has revealed that rotational vibrations are responsible for the disappearance of the zone of non-uniqueness.

In this work, we experimentally investigated the dynamics of vapor-gas bubbles arising in distilled water under the action of ultrasound (US), near and on the surface of solid plates with various surface properties. In the experiments, we used the plates made of Teflon, acrylic glass, and amorphous quartz, with various hydrophobic properties (contact angle). The experiments showed a significant effect of surface properties on the dynamics of bubbles oscillating near and on a solid surface under the influence of ultrasound. In the case of a hydrophobic surface (Teflon), steady attachment of bubbles is observed, the surface area covered by the bubbles grows according to a law close to linear, and then it reaches a plateau. For less hydrophobic surfaces, the drift and rising of bubbles along the plates are observed, as a result of which, the area covered by the bubbles grows less rapidly over time. When the ultrasound is switched off some bubbles located near and on the surface of the acrylic plate float and drag other bubbles with them, differ from the surface of Teflon. This behavior of the bubbles limits both their maximum possible diameter and the maximum solid surface area covered by the bubble. In addition, experiments showed a significant effect of the concentration of gas dissolved in a liquid on the process of bubble formation: a decrease in gas concentration led to a qualitative change in the time dependence of the surface area covered by the bubbles; in the case of long-term degassing of water using ultrasound, the formation of extended bubble clusters on all solid surfaces becomes impossible.

The difficulties of beneficiation of the potash ores by flotation is controlled by the structural similarity of the soluble salt minerals such as halite NaCl and sylvite KCl leading to the same surface properties and reactivity of those minerals when cationic reagents are used as collector. In this work, the effect of sonication on the selective flotation and separation contrast between sylvite KCl and halite NaCl in saturated salt solutions was investigated. The flotation experiments were performed on the potash ore samples from the Verkhnekamskoye deposit, Russia, using primary amine as the collector. Different particle sizes (0.5–1 mm, 0.25–0.5 mm, and 0.1–0.25 mm) with similar contents of K (26–29 %) and Na (16.5–18 %) and the same mineralogical compositions were studied. Pulp sonication was performed during the conditioning and/or flotation stages at 30 % solid content in a mechanical flotation machine using an ultrasonic generator at powers from 10 to 75 W at a resonant frequency of 20 kHz. In the absence of the sonication, the maximum recovery of sylvite was obtained for the size fraction of 0.25–0.5 mm (93.99 %) while the sylvite recovery was low for the coarse-grained fraction (0.5–1 mm). The lowest flotation selectivity was observed for the fine-grained ore sample (0.1–0.25 mm). The combined ultrasonic treatment of this sample during conditioning and flotation approximately halved the recovery of NaCl in the potash concentrate (from 17.9 % to 9.9 %) and increased the KCl recovery from 89.9 % to 95.9 %. The addition of a frother increased significantly the sylvite recovery under sonication for coarse size fraction while the effect was less prononoced for the intermediate size fraction. The enhanced flotation selectivity between KCl and NaCl under sonication was attributed to the increased detachment of weak hydrophobic NaCl particles from air bubbles according to the particle size and mode of treatment. The collector desorption from the halite surface unrevealed by the diffuse reflectance infrared spectroscopy was suggested as a factor controlling the selective detachment of low hydrophobic particles under sonication. Therefore, based on our results, a balance must be established between the particle size, collector consumption, ultrasound treatment power, and sonication method (during conditioning with reagents or/and flotation) to optimize the separation between NaCl and KCl.

Failure analysis shows that 80–85% of emergency boiler shutdowns at power plants result from heating surface damage. When in service, the tubes are exposed to alternating thermo-mechanical loads, which trigger phase change affecting the individual service life. The service life sometimes differs significantly from its estimated value. This research is based on the hypothesis about the role and influence of internal structural stresses on the actual strength and long-term performance of tube products made of steels and alloys. The purpose of this work is to determine the limit state region of internal stresses of the first kind, in which microdamage will not lead to fracture. For that, we did a set of experiment studies to model the accelerated aging processes by thermal cycling and cold cyclic deformation. We chose a tube made of austenitic steel 10Cr13Mn12Si2Ni2Cu2Nb (Di59) as the object of research. The methods used were XRD analysis, microhardness testing, X-ray spectroscopy, and microstructure analysis. Due to redistributing properties, steel has no stable states: all its states are short-term and dependent on external disturbances. In accordance with the suggested hypothesis, the research findings make it possible to forecast the trends and direction of changes in the material properties. This allows us to evaluate the achievement of the limit state by the object and to use relaxations of internal stresses as a sign determining the conditions of crack initiation and propagation. The results are confirmed by the data obtained from the microstructure analysis of fractured tubes of a superheater from a functioning boiler.

The present paper is concerned with studying the onset and nonlinear regimes of convection in a binary liquid mixture with negative separation ratio in square cavity heated from above. The problem of temporal evolution of small perturbations of the non-stationary base state is solved in the framework of the linear approach. A direct numerical simulation based on the solution of full unsteady equations is carried out. The results of calculations show that the wavelength of the most dangerous perturbations and the time of the onset of instability decrease with the growth of solutal Rayleigh number (level of gravity) according to the power laws. The data on the structure of the critical perturbations and nonlinear regimes established after the loss of stability are obtained. The results of direct numerical simulation are compared with the dependencies of the onset time of instability and wave number of the most dangerous perturbations on the solutal Rayleigh number, obtained by solving the linear problem of temporal evolution of small perturbations; good agreement is found.

The effect of acoustic wave propagating in longitudinal direction on stationary convective flow in a horizontal channel of rectangular cross-section in the presence of horizontal temperature gradient and its stability is studied. It is shown that in the presence of sufficiently intensive acoustic wave stationary flow is of coaxial character, the fluid moves in the direction of temperature gradient near sidewalls and in the opposite direction in the interior of the channel. At Pr

The welding process has a significant impact on the chemical composition, structure and mechanical properties of materials in heat-affected zones. The existing approaches to the diagnostics cannot predict the properties of the welded joint nor do they guarantee its reliable performance throughout the projected service life. This becomes especially relevant when investigating the welds from heterogeneous steels applied in power engineering. The main goal of this paper is to offer modern approaches to the complex technical diagnostics of steam pipelines using X-ray investigation of heterogeneous weld structures. In this work, the following research methods were used: X-ray fluorescence analysis, X-ray diffraction method, and microhardness measurement. The object of the investigation is the composite weld of 12Cr18Ni9Ti austenitic steel and 12Cr1MoV pearlitic steel. The results of this investigation show that the properties of the weldable steel changed significantly as compared to its original state. The weld structure was represented by the internal structural stress gradients despite the application of the stress relief heat treatment. The proposed approaches to the study of steel welds can be used for selecting the rational mode of post-weld heat treatment. Combined with traditional inspection methods (visual or ultrasonic inspection, etc.), these approaches can serve as a basis for technical diagnostics and the selection of constructional materials.

The onset of convection in a horizontal layer of an electrically conducting fluid heated from below is studied in the presence of a horizontal magnetic field rotating about a vertical axis. Two different ranges of the rotation frequency are considered: (1) the case of high frequencies of rotation for which the averaging approach is used and (2) the case of finite frequencies for which the averaging approach might be implemented. It is shown that in general the magnetic field stabilizes the static state of pure thermal conduction. However, there exists a parameter range where the inhomogeneity of the magnetic field is strong enough to provide energy for the growth of disturbances even if the fluid layer is stably stratified.

Much of modern molecular and cell biology research relies on the ability to purify cell types by fluorescence activated cell sorting (FACS). FACS typically relies on the ability to label cell types of interest with antibodies or fluorescent transgenic constructs. However, antibody availability is often limited, and genetic manipulation is labor intensive or impossible in the case of primary human tissue. To date, no systematic method exists to enrich for cell types without a priori knowledge of cell type markers. Here we propose GateID, a computational method that combines single-cell transcriptomics with FACS index sorting to purify cell types of choice, using only native cellular properties such as cell size, granularity and mitochondrial content. We validate GateID by purifying various cell types from the zebrafish kidney marrow and the human pancreas to high purity without resorting to specific antibodies or transgenes.

The linear stability problem of homogeneous vertical seepage of the liquid mixture through a closed region of porous medium is investigated. The problem is solved taking into account immobilization of the solute by the porous medium, which is described within the MIM approach based on the second-order kinetics model allowing for the saturation of the solid matrix of porous medium with immobilized solute. The stability of the homogeneous vertical seepage mode to two-dimensional perturbations has been considered for the case of square porous domain. It is assumed that the lower and upper boundaries are maintained at fixed different concentrations of solute and the lateral boundaries are impermeable to the mixture. It has been found that due to consideration for the solute immobilization the perturbation spectrum of the homogeneous vertical seepage mode exhibits oscillatory perturbations which are absent in the case of using the classical diffusion model. Neutral curves for the space of the respective parameters and plots of neutral perturbation frequency as the function of governing parameters have been obtained numerically. It has been shown that in the presence of the immobilization the stability of the examined seepage mode decreases as compared to the classical diffusion model. The numerical investigation has shown that the oscillatory mode of convection exists only in a certain range of parameters characterizing the intensity of sorption. The maps of oscillatory instability mode existence in the space of governing parameters have been obtained.

We investigate a linear stability of the lower boundary of the hydrate stability zone (or the HSZ boundary) for deposits located in permafrost regions under the conditions of the geothermal gradient in the gravity field. We consider porous layers, one of which is saturated with methane and hydrate and another is saturated with methane and ice. Porous layers are of different permeabilities. The two types of background porous systems are studied: a discretely layered porous medium comprising two porous layers of constant different permeabilities, and a continuously layered porous medium consisting of a layer with permeability continuously varying with depth. It has been shown, that an essential difference in permeabilities of layers leads to the excitation of the “local convection” within the lower more permeable gas-ice layer, whereas at close values of layer permeabilities the instability occurs in the form of a “large-scale convection” covering both the gas-ice and gas-hydrate layers.

The effect of high-frequency small-amplitude vertical vibrations on the stability of a conductive state of a two-layer system of immiscible fluids with a constant vertical heat flux imposed at external boundaries is studied within the framework of the generalized Boussinesq approximation taking into account the interface deformation. It is found that the long-wave instability is not affected by vibrations of small and moderate intensity. The impact of vibrations on the stability to the perturbations of finite wavelength is analyzed for the model system of fluids which have identical properties except densities and for the real system “formic acid – transformer oil”. For model system it is found that the stability boundary to the oscillatory finite-wavelength perturbations has the segment where vibrations make stabilizing effect and the segment of the destabilizing effect of vibrations. For real system “formic acid – transformer oil” vibrations reduce the conductive state stability to the monotonic finite-wavelength perturbations and increase the stability to the oscillatory finite-wavelength perturbations. As a result, the monotonic finite-wavelength perturbations become the most dangerous at high enough values of the vibrational Rayleigh number.

The effect of thermal boundary conditions on linear stability of stationary convective flow in a horizontal layer subjected to the longitudinal temperature gradient and propagating acoustic wave is studied. Two-dimensional shear instability and three-dimensional monotonic and oscillatory instabilities are analyzed. The stability maps for different acoustic Reynolds number values with respect to different perturbation types are obtained. The stabilization under the influence of acoustic wave at low Prandtl numbers is demonstrated. It takes place when two-dimensional shear or three-dimensional oscillatory instability modes are most dangerous. Three-dimensional monotonic mode is destabilized by acoustic influence. Energy analyses for two-dimensional and monotonic three-dimensional modes of instability is carried out.

Kinetics of the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) over Pd supported on hypercrosslinked polystyrene bearing amino-groups was studied at variation of the MBY-to-Pd ratio and reaction temperature. For the catalyst, containing 0.7 wt.% of Pd, optimal reaction conditions were found providing >98% of the MBE selectivity at 95% of the MBY conversion. Kinetic modeling and temperature variations as well as studies of a hydrogen consumption rate allowed us to suggest that a thermodynamic factor is most likely responsible for the high MBE selectivity.