When solving problems based on the nonlinear Korteweg–de Vries (KdV) equation, it is necessary to understand how calculations should be performed taking into account the dissipative component. This issue is quite urgent, and the main purpose of this report is to find the analytical representation of the solution of the dissipative KdV equation. The main method of solving the dissipative KdV equation used in this study is a formal transition to a new variable, which allows one to represent the solution in the form of a soliton in a very compact form. The analysis given in this Letter makes it possible to automatically take into account attenuation, which can be of a diverse nature, depending on the real environment with which the soliton interacts. This result is the main conclusion of this study.

The results of a study by transmission electron microscopy of the structural state of α-Ga2O3 film with a thickness of about 1 micron, grown on the prismatic m-face sapphire by the method of chloride vapor phase epitaxy, are presented. The influence of the substrate orientation on the formation of the dislocation structure is discussed. Threading dislocations, including those with the Burgers vector 1/3< 1120 >, and dislocation half-loops are revealed. The inclined propagation of dislocations and the formation of dislocation half-loops result in the reduction of the threading dislocation density near the surface.. Keywords: dislocations, gallium oxide, TEM.

The influence of the orientation of Ti–Al interphase boundary on the intensity of mutual diffusion, as well as the influence of its deformation of Ti at temperatures above the melting temperature of Al, were studied by the method of molecular dynamics. Zope and Mishin EAM potentials were used to describe interatomic interactions in the Ti–Al system. Three orientations of the boundary relative to the hcp Ti crystal were considered: $$(0001)$$ , $$(10\bar {1}0)$$ , and $$(10\bar {1}1)$$ . It was found that the orientation of the interfacial boundary affects the intensity of diffusion in the Ti phase: Al atoms diffused more intensively into the titanium lattice at the $$(0001)$$ orientation and less intensively at the $$(10\bar {1}0)$$ and $$(10\bar {1}1)$$ orientations. This influence of the orientation of the interphase boundary is associated with the probability of detachment of the Ti atom from the crystal–liquid interface and is determined by the difference in the energies of the Ti atoms in the aluminum phase and those built into the boundary of the crystalline phase. At the initial stage of mutual diffusion, the boundary between the crystal and liquid metal was observed to shift from the very interface between Ti and Al by two or three atomic planes into the aluminum phase—a thin layer of aluminum near the boundary remained in the crystalline state, repeating the crystal lattice of titanium. This is due to the fact that the Ti–Al bonds at the boundary are much stronger than the interatomic bonds in liquid aluminum. When studying the effect of elastic deformation on the intensity of mutual diffusion, it was found that, in almost all cases, the intensity of diffusion increases with tension and decreases with compression, which is associated with a corresponding change in the free volume, which largely affects the diffusion mobility of atoms.

This work presents computer modeling of reimination of 1,2-ditert-butylethanediimine in aqueous acetonitrile medium with the formation of 2,4,6,8,10,12-hexaacetyl-2,4,6,8,10,12-hexaaxatetracyclo-[5,5,0,03,11,05,9]dodecane. At the level of density functional theory, using BP86 and the def2-SVP basis set, a hypothetical mechanism of reimination reaction was modeled in the conductor-like polarizable continuum model of solvent at 298.15 K. The change of Gibbs functions G at 298.15 K and internal energy U at 0 K for all stages of the hypothetical mechanism was compared. It was established that formation of the target cyclic product is possible by the method of reimination of 1,2-ditert-butylethanediimine in aqueous acetonitrile medium in aminoacetic acid. Due to the significant influence of the entropy factor in the intermediate stages, a decrease in temperature should facilitate the synthesis.

The article presents the results of studies of the optical and photocatalytic properties of titanium oxide thin films deposited by cathodic arc deposition in an oxygen-containing atmosphere. It has been shown that thin films with various oxidation degrees are deposited depending on the oxygen flow rate into the operating chamber. Study of the obtained films has shown that the films obtained in the transition mode between the deposition of Ti metal films and TiO2 dielectric films have the maximum photocatalytic activity. This deposition mode is observed when the oxygen flow rate into the operating chamber is from 9 to 12 cm3/min.

The state of the immune system is a critical indicator of the body’s viability. Population-immunity assessment is an important characteristic of adaptive capacities in resisting environmental physical and chemical stress factors. In modern conditions, populations of aquatic organisms experience toxic stress, which primarily affects the functioning of their immune systems. Speed and quantitative indicators of the development of a humoral immune response in stressed organisms decrease, and immunodeficiency develops. In a special case, in which immunosuppressive changes are recorded on a massive scale for a number of species in the trophic chain, this indicates an increasing crisis in the aquatic biosystem and a decrease in the resistance of the links of the trophic chain to anthropogenic impact. Uncompensated transformations occur in biophysical processes. To identify stress factors, a method of analyzing the forms of the immune response is needed, which should be easily applicable to the diagnosis of immunodeficiency immediately in marine research conditions. The authors develop an original method of analyzing the state of the immune system, which is applicable with the least complexity of laboratory studies to assess the adaptive capabilities of populations of mass fish species. The nature of secondary immunodeficiency has been studied on the example of fish inhabiting in the northern and southern parts of the Russian sector of the North Caspian. The study was conducted on the basis of a modified approach to the study of the immune system, consisting in the identification of a natural inhibitory factor in biological fluids. It is shown that the level of secondary immunodeficiency is an integral indicator that expresses not only the state of the immune system, but also the physiological status of the studied fish and their adaptive capabilities. In the studied areas of the North Caspian, the worst indicators of secondary immunodeficiency were found in gobies (family Gobiidae, genus Proterorhinus, Neogobius, Mesogobius) caught in the areas of Maly Zhemchuzhny Island. The formation of immunodeficiency is associated with prolonged exposure to gobies of flood waters contaminated with toxic substances. The most sedentary representatives of the aquatic fish community, which fully experience the physical and chemical effects associated with large-scale oil production in the North Caspian Sea, were specially selected as objects of research. The authors recommend using the results of immunochemical studies of the goby population as bioindicators for predicting the ecological state of all links of the trophic chain of the Caspian Sea.

The optimal shape of the ending part of a cathode for electrical-discharge machining of dielectrics, which provides an increased rate of removal of dielectrics without changing any physical and technical parameters of the discharge, is proposed in this study. It is established that the rate of removal of the material when using a cathode with a conical end is five times higher than in the case of using a cylindrical end, which is a consequence of the natural superposition of the ultrasound cavitation on pulsed discharges.

The results of experimental studies of the processes of fragmentation of liquid-biofuel droplets based on water, rapeseed oil, and biomass during heating in a high-temperature gaseous medium in the microexplosion and puffing modes are presented. The ranges of temperature variation are established at which the regimes of partial fragmentation and complete microexplosive disintegration of droplets are stably implemented. When processing videograms, the delay times for fragmentation and the total lifetime of droplets are calculated. The influence of the concentration of components in a droplet on the conditions of heating, evaporation, fragmentation, and their ignition has been determined.

The interference method for determining the velocity of objects using direct optical heterodyning (photonic Doppler velocimetry) has become widespread due to the ease of setting up the fiber-optic system, the unambiguous results that it produces, and the wide possibilities for varying the measurement accuracy and temporal resolution. The accuracy of velocity measurements can be fractions of a percent, but there are a number of factors that interfere with this. For example, a change in the velocity of an object, that is, its movement with acceleration, leads to a broadening of the signal spectrum with an increase in the working time window and, as a result, to a decrease, rather than an increase, in the accuracy of measuring the velocity. In this letter, a method is proposed that allows one to compensate for the effect of acceleration on the accuracy of velocity measurement. The proposed model for processing the registered signals makes it possible to determine both the acceleration and the velocity of the object. The applied algorithm made it possible to avoid the expansion of the spectrum with an increase in the time window and to improve the accuracy of measuring the velocity of a freely falling body by an order of magnitude.

We studied the ability of Cu 82.5 wt %–Al 13.5 wt %–Ni 4.0 wt % martensitic single crystals to perform work by moving a load with an impact during the shape-memory-strain recovery of reverse martensitic transformation. The dependence of this work on preload is studied. The transition to the impact mode occurs after the precompression of the crystal until the complete deformation of the shape memory (~9%) when the load exceeds the martensite detwinning stress by more than a factor of 2. Differential scanning calorimetry showed that, after such compression of the crystal to 200–250 MPa and more, the temperature range of the reverse martensitic transformation sharply narrows.