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Orbital invariants of integrable billiards on two-dimensional book tables are studied at constant energy values. These invariants are calculated from rotation functions defined on one-parameter families of Liouville 2-tori. For two-dimensional billiard books, a complete analogue of Liouville’s theorem is proved, action–angle variables are introduced, and rotation functions are defined. A general formula for the rotation functions of such systems is obtained. For a number of examples, the monotonicity of these functions is studied, and edge orbital invariants (rotation vectors) are calculated. It turned out that not all billiards have monotonic rotation functions, as was originally assumed by A. Fomenko’s hypothesis. However, for some series of billiards, this hypothesis is true.

This study investigates the extraction of rhenium using trialkylbenzyl ammonium chloride (TABAC) as an alternative to trialkylamine (TAA) for recovering rhenium from highly diluted solutions. Rhenium, present as ReO4− over a wide acidity range, was extracted via an anion exchange mechanism in single-stage experiments monitored by inductively coupled plasma mass spectrometry (ICP-MS). Key variables, including pH, acid concentration, and the concentrations of extractant and metal, were examined. The results demonstrated a high extraction efficiency exceeding 99% within a pH range of 2 to 7 and from solutions containing sulfuric or hydrochloric acid at concentrations of 0.1 to 3.0 M (mol/L). However, extraction from nitric acid solutions was less efficient, with less than 30% recovery. Performance for both TAA-kerosene and TABAC-kerosene followed the order H2SO4 > HCl > HNO3. The optimal TABAC concentration was 10−2 M (mol/L) in kerosene. TABAC also showed higher selectivity than TAA, with separation coefficients Re/Mo = 66.8 and Re/W = 55.8 in 0.1–1.0 M (mol/L) sulfuric acid. Based on equilibrium studies, the complexes formed during extraction were identified as [R3R′NH]ReO4. This approach may offer environmentally friendly and cost-effective benefits for large-scale industrial applications, enabling efficient recovery of valuable rhenium while reducing waste and environmental impact.

We consider integral Hamiltonian systems (IHSs) with two degrees of freedom containing noncompact fibers under the condition of energy constancy. For such systems, analogues of the edge orbital invariant are studied, classifying IHSs on regular, topologically stable Liouville foliation sections with noncompact fibers (planes and cylinders) with respect to orbital equivalence. It turned out that in the case of cylindrical fibers such invariant is the number of fibers with closed trajectories. If the fibers of two systems are homeomorphic to the plane, then the systems are smoothly conjugate on the corresponding regular parts of the Liouville foliation.

The structure and operating principle of a fuel cell with a polymer proton-exchange membrane are described. The morphology of superhydrophobic fluoroplastic coatings on the surfaces of carbon fibers of gas-diffusion layers under development is examined. The water resistance of gas-diffusion layers characterizing the resistance of this carbon-fluoropolymer composite to water flow is studied as a function of the fluoroplastic matrix content. The efficiency of using not only suspensions of polytetrafluoroethylene but also dilute lacs of modified polyvinylidene fluoride is confirmed. A comparative analysis found that the developed gas-diffusion layers had operating parameters (specific electrical resistance, porosity, thickness, surface density, and hydrophobicity) comparable to those of imported industrial analogs.

The article is devoted to an experimental study of the influence of wear-resistant coatings ZrN, TiN + ZrN, (Ti–Zr)N, ZrN–(Ti–Zr)N–TiN, and TiN, deposited on T15K6 hard alloy inserts, on the tribological and deformation characteristics of the process of turning 45 and 12Kh18N10Т steel workpieces, and subsequent comparison of the calculated values of the maximum temperatures of the rake face of the lathe cutter. When processing 45 steel, a significant reduction in contact and average temperature in the cutting zone is ensured by a combination of tribological and deformation indicators when using TiN + ZrN and ZrN + (Ti,Zr)N + TiN compositions. When turning 12Kh18N10T stainless steel, the presence of coatings on carbide inserts had a lesser effect on the course of deformation processes. The main effect of modifying the working surfaces of the tool is to change the thickness of the zone of secondary plastic deformations and to reduce the length of contact between the chips and the rake face. In this case, the greatest effect in reducing surface temperatures due to the influence on the complex of tribostrain indicators and enhancing the thermodissipative capabilities of the contact zone is demonstrated by ZrN and ZrN + (Ti,Zr)N + TiN coatings. Based on the results of full-scale experiments and digital modeling using the obtained experimental data, it was established that the temperature distributions in the area of tribocoupling of chips with the surface of a hard alloy in the presence of a multilayer coating on it are associated with the wear of metal-cutting tools, which makes it possible to evaluate the impact of wear-resistant coatings through changes in the temperature regime in the contact zone. Such an influence of surface modification on a set of tribostrain indicators, which also determine the nature of the distribution of contact temperatures, should be taken into account when developing new compositions and structures of wear-resistant coatings along with their physical and mechanical properties at the microlevel.

The market and manufacturers of hydrogen fuel cells are analyzed. The main types of fuel cells and their operating principles are discussed. The main requirements applied to gas-diffusion layers and their main properties are identified. Domestic technology of gas-diffusion layers as carbon–carbon composite materials is described. A scheme for producing gas-diffusion layers as carbon–polymer composites based on carbon fibrous materials from cellulose hydrate or polyacrylonitrile is given. Hydrophobization of gas-diffusion layers is performed using fluoroplastics. The technology can be shortened and economized by fabricating gas-diffusion layers as carbon–polymer composites.

The article is a continuation of the research on creating the most complete and representative earthquake catalogs by combining all available data from regional, national, and international seismological agencies and reducing magnitudes to a uniform scale. The task of identifying and removing duplicates that arise during the merging process is solved using the authors’ modification of the nearest neighbor method. It is evident that the intelligent merging of different earthquake catalogs for the same territory will improve the completeness and representativeness of events in the final integrated catalog. In this article, the earthquake catalog of the western sector of the Arctic zone of the Russian Federation (AZRF) covering the period 1962–2022 was created by merging three regional Russian catalogs and the ISC catalog. The ratio of magnitude types in the catalog for different seismic networks was analyzed, and magnitude estimates were unified based on the obtained ratios. For analyzing seismic activity in the western AZRF, it is recommended to use earthquakes from the period 1998–2020 when the catalog was significantly cleaned from explosions and other events of the “non-earthquake” type.

The aim of the research was to study the transcutaneous diffusion kinetics of desloratadine from two types of matrix patches containing the active substance in ionic and nanostructured forms (in the form of micelles based on Tween-80). The study included an assessment of the efficiency of desloratadine transport through a cellulose membrane and through rat skin using Franz diffusion cells. Desloratadine and patch components were quantitatively determined using UV spectrometry. The results showed that matrix patches containing desloratadine in micellar form provided a more complete and prolonged release of the active substance in experiments with rat skin, which confirmed their potential for use as an effective form of transcutaneous delivery of this drug.

One of the main problems in a design of rigid bus structures in open switchgears devices is a structural stabilization under the influence of various dynamic loads. The implementation of rigid bus structures with large spans of pipe-bus showed a real danger of the wind resonance for cylindrical pipe-bus structures (aeroelastic oscillations). This phenomenon is dangerous in that at low wind speeds there are intense pipe's oscillations in vertical plane, adding to the static loads an essential dynamic component. Its level is comparable with the loads from the weight of the structures and can, in combination with the rest loads, cause stresses close to the maximum admissible for the 1st group of limit states. The problem of reducing the level of structural oscillations in many cases is associated with the need to increase the rigidity and reduce the material consumption, but it's important to meet the technological requirements imposed by operating conditions and protect people from harmful vibration. In a paper are considering a new method for damping oscillations for rigid bus structures under the action of a wind vortex excitation – damper as a rigid insert. Is presented a mathematical model of the joint work of the rigid bus structure with the damper as the rigid insert. Have carried out analytical researches of the joint work of the rigid bus structure with the damper as the rigid insert.

This work is dedicated to assessing the effect of TiN, ZrN, TiN + ZrN, (Ti–Zr)N, ZrN–(Ti–Zr)N–TiN nanostructured coatings, deposited on plates of hard alloy T15K6 by the PVD method, on tool wear and thermoelectric parameters of the process of turning work pieces from steels 45, 38HS, and 12H18N10T. The greatest decrease in temperature in the cutting zone was recorded during the processing of steels 45 and 38HS, characterized by high thermal conductivity coefficients, while the maximum effect was achieved due to TiN + ZrN and ZrN coatings, for low thermal conductivity steel 12H18N10T, the lowest temperature was provided by the ZrN, (Ti–Zr)N and ZrN + (Ti–Zr)N + TiN compositions. Analysis of the variable component of the thermo-EMF signal during cutting shows a decrease in the amplitude of oscillations for coatings that provide the greatest wear resistance of the tool. According to the results of the experiments, such an effect when turning steels 45 and 38HS at optimal speeds was demonstrated by ZrN + (Ti–Zr)N + TiN and TiN + ZrN coatings, and for stainless steel 12H18N10T, ZrN, ZrN + (Ti–Zr)N + TiN and TiN. The established relationship between the wear resistance of carbide inserts and the amplitude of fluctuations of the variable thermos-EMF component makes it possible to use it as an indirect criterion for selecting the optimal composition of the wear-resistant coating from the point of view of thermophysical compatibility with tool and machined materials.