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The most promising directions of the development of heat-resistant alloys (HRAs) based on refractory metals are analyzed. The microstructures characteristic of HRAs, which it is advisable to form in promising alloys, are considered. The stability factors of the microstructure with respect to the diffusion coarsening of the hardening phases are discussed. Two groups of alloys are considered as the most promising HRAs based on refractory metals. First, the principles for design of HRAs based on (Pt, Ir)-Sc with heterophase γ-γ’ microstructure, where γ-matrix is a (Pt, Ir) solid solution with a FCC lattice, and γ’ is a strengthening phase with the structure L12 by analogy with Ni-base superalloys, are developed. The resistance of γ-γ’ microstructure in Ni, Pt and Ir alloys against the process of diffusion-limited coarsening is analyzed. It is shown that the diffusion permeability of Pt is several times less than that of Ni, so one should expect that Pt-based HRAs will not be inferior to Ni-based HRAs in terms of structural stability. The second group includes HRAs based on many not noble refractory metals. It is shown that solid solutions of the system (Ti, Zr, Hf, Ta, Nb) with a BCC lattice can be considered as a matrix of advanced refractory HRAs. The results of experimental studies of alloys based on (Ti, Zr, Hf, Ta, Nb) additionally alloyed with elements contributing to the formation of strengthening intermetallic and silicide phases are discussed. The issues of segregation of alloying elements at the grain boundaries of refractory alloys and the effect of segregation on the cohesive strength of the boundaries are considered.

The study explores the dynamics of public transport regulation, deregulation, and reform within the context of Tver in Russia. As developing nations face increased transportation demand and industrialized regions grapple with environmental concerns policymakers are challenged to choose appropriate regulatory frameworks. Historically, different stages of economic development have led to diverse approaches, ranging from publicly owned enterprises to natural monopoly regulation. Primary objective of the study is to conduct a spatial analysis of the new public transport route network in Tver and its suburb, examining alterations, accessibility, and travel times. To achieve this, methodologies, and data parameters such as Geographic Information System (GIS) tools for spatial analysis, creation of buffer zones around public transport stops to assess accessibility, population coverage analysis to understand the demographic impact, and isochrones mapping to evaluate changes in travel times and accessibility were employed. These methods allowed for a detailed assessment of the network's alterations, accessibility, and the impact on travel times following the transfer of planning authority. Additionally, population access to transport services was assessed through demographic coverage analysis, determining the proportion of the population within a designated distance from stops. These quantifications provided insights into the effects of transferring planning authority on the regional public transport system's accessibility and efficiency. Tver's experience illustrates the potential outcomes of transport reform, with intracity and intraregional routes merged into a unified passenger transportation system. This transformation holds promise for regional development. In summary, this study offers insights into public transport regulation and reform dynamics, using the Tver case to analyze the consequences for accessibility and service quality. [ABSTRACT FROM AUTHOR]

The article presents a literature review of pediatric abdominal surgical emergencies in the Russian Federation. The article considers the issues of the development of laparoscopic surgery in pediatrics, the current state of this problem in surgical hospitals, the difficulties associated with transition to minimally invasive surgical interventions, in providing emergency surgical care for children. The possible risks of laparoscopic access and methods for their reduction were analyzed. The advantages of this technique were specified in comparison with open surgical interventions. The reliable economic efficiency of the offered technique was demonstrated. The analysis of the literature sources showed that there was no consensus on laparoscopic treatment for complicated abdominal diseases after previous open repair; and there were also no clear algorithms in clinical practice for complete transition to laparoscopic surgery in children. The analysis revealed very few economic studies on the efficacy of laparoscopic interventions.

The modern approach to the design of heat-resistant metal alloys (HRAs) is analyzed, according to which the creep rupture characteristics of an alloy are mostly determined by the strength of interatomic bonding at grain boundaries (GBs) and in the bulk of a matrix phase. The main attention is paid to the concept of “low alloying additions” to polycrystalline alloys with transition metals, because of which the cohesive strength of the GBs and the cohesion energy of the alloy matrix are increased. This approach is especially important in relation to alloys obtained by powder metallurgy, which, in the compacted state, are fine-grained polycrystals. The methodology for calculating the key parameters of the theory (the energy of impurity segregation to the grain boundaries Egb and to the free surface Efs, as well as the values of the partial molar energy of the cohesion of the alloys) from the first principles is given. The results of applying the theory to the study of Ni-, Cr- and Ti-based alloys and the development of new HRAs based on them are presented. Typical defects in the microstructures of objects obtained using additive technologies (AT) and the application efficiency of standard methods of processing powder alloys (Hot Isostatic Pressing (HIP), heat treatment (HT)) to improve the microstructure and increase the mechanical properties are considered.

We use ab initio calculations to analyze the influence of 4d and 5d transition metal alloying elements on cohesive properties of the bulk and a representative grain boundary in Cr within the framework of the Rice–Thomson–Wang approach. The results obtained for Cr are combined with the analogous results for Ni to select Ta and Nb as promising alloying additions to dual-phase (α/γ) Cr-Ni-base high-temperature alloys. Ta and Nb are added to the alloying system of an existing alloy I (Cr-Ni-W-V-Ti) in an attempt to design a chemical composition of a new alloy II (Cr-Ni-W-V-Ti) + (Ta-Nb). Investigation of the microstructure of the Ta-bearing Cr-Ni-alloy reveals a Ta enrichment of large γ-areas near GBs in α-matrix that we consider as potency to increase the cohesive strength of GBs and the cohesive energy of the bulk in γ-phase. Mechanical testing of alloys I and II demonstrates that the alloy II has improved tensile strength and creep resistance at high temperatures.