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The reliability of the scientific research results is largely determined by the level of adequate selection and complexity of methods, obtaining objective data. It is also a determinant of the scientific information structure and content quality, its processing and generalization. The purpose of the study was to select and characterize a methodic complex for obtaining objective data of monitoring the students’ performance in the process of swimming training. Material and methods. We used theoretical analysis of scientific and methodical data, sources of the Internet, documentary sources, system analysis, historical and logical, comparative analysis and extrapolation, synthesis and modeling. Results and discussion. The implementation of the system of training students swimming cannot take place without correct control over this process. Due to the need of objective evaluation the effectiveness of different methodical content of training swimming programs, there is a need to find the complex of indicators (based on available diagnosis methods and techniques). For in-depth and extensive study of student youth’ indicators in the process of swimming training and implementation of basic control tasks in pedagogical research proposed 22 methods for determining the physical development and functional condition, 15 tests and exercises for determining the physical fitness of students, 5 indicators for determine psychophysiological characteristics and more than 20 indicators for monitoring the swimming preparedness of students. Conclusion. The theoretical part of any research involves in-depth study and characterization of physical education external and internal factors at different educational levels. For substantiating, developing, and implementing the main research results we used scientific and methodological data, significant number of basic research in the field of physical culture and sports, regulations and management protocols of physical education in higher education institutions etc. Tests complexes for evaluation of physical fitness, findings of physical development, psychophysiological indicators, data of swimming fitness, and objective indicators of the functioning the basic systems of the students’ body are formed with taking into account the recommendations of special literature. The research provides appropriate metrological requirements, which allow selecting tests that are easy to reproduce and provide simple but reliable ways to results fixation

The results for thermal stability of the microstructure and mechanical properties of ultrafine-grained alloys Zr-1 wt. % Nb and Ti-45 wt. % Nb alloys after long-term thermal annealing at temperature of 400°C are presented. It is shown that in the Zr-1 wt.%Nb alloy in the ultrafine-grained state, increase in the annealing duration from 5 to 360 hours leads to growth of the structural elements (grains, sub-grains, fragments) of the matrix phase a - Zr and the particles β-Nb. This fact is due to the processes of recrystallization. It leads to softening of the alloy and decrease of microhardness and yield stress. It was also found that annealing up to 360 hours does not affect the size of the structural elements of the matrix β-phase in the Ti-45 wt. % Nb alloy, but contributes to the noticeable growth of the α-phase and ω-phase grains. According to our results, softening of the Ti-45 wt. % Nb alloy and decrease in its mechanical characteristics are associated with the processes of return at the grain boundaries, as well as with growth of the nanoscale grains of α-phase and ω-phase and decrease in their contribution to dispersion hardening.

New TiNb-based alloys, such as Ti–6Al–7Nb, are currently being studied around the world as an alternative to other Ti alloys, e.g., instead of Ti–6Al–4V. We conducted a pilot study where thin (approximately 1.2 micron) CaP coatings containing low doses of Zn2+ (0.4–0.8 wt.%) were prepared by the radio frequency magnetron sputtering (RFMS) of Zn-hydroxyapatite (HA) target on Ti–6Al–4V and Ti–6Al–7Nb substrates and investigated their physicochemical properties, in vitro solubility, cytotoxicity, and antibacterial and osteogenic activities. The thickness of the obtained coatings was approximately 1.2–1.3 microns. Zn substitution did not result in roughness or structural or surface changes in the amorphous CaP coatings. The distributions of Ca, P, and Zn were homogeneous across the film thickness as shown by the EDX mapping of these elements. Zn doping of CaP coatings on both types of Ti-based alloys statistically influenced the results of the scratch-test. However, obtained values are satisfactory to use Zn-CaP coatings on biomedical implants. Increased Zn2+ release vs. tapered output of Ca and phosphate ions occurred during 5 weeks of an in vitro immersion test in 0.9% NaCl solution. Ti–6Al–7Nb alloy, unlike Ti–6Al–4V, promoted more linear biodegradation of CaP coatings in vitro. As a result, CaP-based surfaces on Ti–6Al–7Nb, compared with on Ti–6Al–4V alloy, augmented the total areas of Alizarin red staining in a 21-day culture of human adipose-derived mesenchymal stem cells in a statistically significant manner. Moreover, Zn–CaP coatings statistically reduced leukemic Jurkat T cell survival within 48 h of in vitro culture. Along with the higher solubility of the Zn–CaP surface, a greater reduction (4- to 5.5-fold) in Staphylococcus aureus growth was observed in vitro when 7-day extracts of the coatings were added into the microbial culture. Hence, Zn–CaP-coated Ti–6Al–7Nb alloy with controllable biodegradation as prepared by RFMS is a prospective material suitable for bone applications in cases where there is a risk of bacterial contamination with severe consequences, for example, in leukemic patients. Further research is needed to closely investigate the mechanical features and pathways of their solubility and antimicrobial, antitumor, and osteogenic activities.

The work deals with the particular combustion characteristics of methane family hydrocarbons (methane, ethane, propane, butane) and wet natural gas with process oxygen at carbon dioxide and water steam dissociation in a state-of-the-art arc steelmaking furnace. An algorithm is developed to calculate chemistry, the amount and concentration of combustion products at carbon dioxide and hydrogen dissociation, their physical and thermophysical parameters; heating power, balance and actual temperature, heat and pyrometric factors are evaluated considering heat transfer by radiation into unbounded medium. Based on the calculation results the recommendations are given for development of cold charge material heating conditions in order to minimize dusting, carbon oxide and hydrogen and charge material loss.

First evaluations of the blackbody-radiation (BBR)-induced shift and broadening of highly excited Rydberg states were based on the account of only the first term of the expansion for the Planck’s distribution in powers of the ratio of the BBR-photon energy to the environmental thermal energy. The corresponding asymptotic expression for the shift is proportional to a sum rule for the oscillator strengths, which is identical for all states, independently of their principal and angular-momentum quantum numbers. The broadening appeared proportional to the sum of the oscillator-strength first moments, which is dependent on only the principal quantum number, being independent of the state’s angular momentum. In this article, we demonstrate that the account of higher-order terms of the Planck’s distribution expansion provides corrections revealing the dependence of asymptotic shift and broadening on the Rydberg-state principal and angular-momentum quantum numbers. The strongest corrections are observed for states with low angular momenta, in agreement with earlier performed numerical calculations. Sum rules for higher moments of oscillator strengths are used for evaluating the corrections for the BBR-induced broadening and shift of Rydberg-state energy levels in neutral atoms and ions of arbitrary nuclear charge Z.

An experimental investigation of flammability limits of hydrogen, methane and propane in air and oxygen at reduced pressures was carried out. A slow influence of sizes of an experimental vessel of a diameter higher than 125 mm on the flammability limits was revealed, but an influence of a type of an oxidizer (air or oxygen) and an ignition energy is significant. Critical values of an initial pressure for a possibility of a flame propagation were determined. The limiting values of the ignition energy were determined, for which an elevation of this parameter does not influence the critical pressure and the flammability region. A qualitative interpretation of obtained experimental results is given, which is based on a peculiarities of a flame initiation.

The objective of the present work is to develop recommendations for controlling the safety of nuclear power plants on the basis of risk assessments and safety certification of nuclear power plants. The Kursk nuclear power plant is considered as an example of a nuclear power plant with an RBMK reactor. The concept of risk assessment of a nuclear power plant consists in constructing a set of scenarios of the appearance and development of possible accidents followed by an evaluation of the realization frequency and determination of the scales of the consequences of each one. The result of an analysis is an evaluation of a system of risk indicators in accordance with the requirements of the safety compliance certificate of the nuclear power plant as well as the development of recommendations for increasing plant safety. In risk assessment, the consequences are divided into categories of the seriousness of the damage, for which their probability is evaluated separately. The graphical interpretation of risk due to any dangerous object consists of frequency-consequences curves. Recommendations are developed on the basis of the results of risk analysis.

The research is involved in producing a Ti-Nb alloy surface layer on titanium substrate by high energy beam method, as well as in examining their structures and mechanical properties. Applying electron-beam cladding it was possible to produce a Ti-Nb alloy surface layer of several millimeters, where the niobium concentration was up to 40% at. and the structure itself could be related to martensite quenching structure. At the same time, a significant microhardness increase of 3200-3400 MPa was observed, which, in its turn, is connected with the formation of martensite structure. Cladding material of Ti-Nb composition could be the source in producing alloys of homogeneous microhardness and desired concentration of alloying niobium element.

It was determined that there is components segregation in Ti-Nb alloy under electro arc melting and selective laser melting. It leads to two phase formation. The [beta]-phase forms in the areas enriched in Nb. [alpha]”-phase forms in the Nb-depleted areas. It is recommended to increase the Nb concentration in the alloy up to 45 wt. % to eliminate heterogeneity of phase and elemental composition.

The study presents the analysis of microstructure, phase composition and mechanical properties of Ti40Nb alloy exposed to severe plastic deformation. It was shown that isothermal multi-axial forging and further multi-pass rolling intensify the formation of ultra-fine grained structure in the bulk of a billet with the average element size of 0.3 μm. Such ultra-fine grained structure considerably improves the alloy mechanical properties.

The phase composition and microstructure of Ti-Nb alloy produced from composite titanium and niobium powder by selective laser melting (SLM) was studied. Produced monolayered Ti-Nb alloy enhanced the formation of fine-grained and medium-grained zones with homogeneous element composition of 36-38% Nb mass interval. Alloy phase composition responded to [beta]-alloy substrate phase (grain size was 5-7 pm) and non-equilibrium martensite [alpha]"- phase (grain size was 0.1-0.7 [mu]m). [alpha]"-phase grains were found along [beta]-phase grain boundaries and inside grains, including decreased niobium content. Alloy microhardness varied within 4200-5500 MPa.