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We present the derivation of simple analytical expressions for calculating the widths of Rydberg states with small orbital angular momenta in Zn+, Cd+, Hg+ ions of group IIb of the periodic system of elements induced by blackbody radiation (BBR) at ambient temperatures from 100 to 3000 K. The probabilities of radiative transitions from excited nS, nP, nD and nF states to all dipole-accessible states of ions are calculated. The wave functions of the quantum defect (QD) method for the initial and final states of the Rydberg electron are used to calculate the amplitudes of transitions between bound states. The dependences of the probabilities of induced decays and excitations on the BBR temperature, the principal and orbital quantum numbers of the Rydberg ion are determined. Analytical expressions are derived for numerical estimates of the contributions of the probabilities of thermally induced decays and excitations to the width of the Rydberg energy level. The numerical values of the coefficients of interpolation polynomials representing asymptotic expansions in powers of the principal quantum number n for the relative probabilities of decays and excitations of Rydberg states with large values of n and small orbital angular momenta l = 0, 1, 2, 3 are calculated.

The results on thermal stability of the microstructure and mechanical properties of Zr – 1 wt.% Nb and Ti – 45 wt.% Nb ultrafine-grained alloys subjected to long-term thermal annealing at a temperature of 400°С are presented. It is shown that in a Zr – 1 wt.% Nb ultrafine-grained alloy an increase in the annealing duration from 5 to 360 hr leads to a growth of the structural elements (grains, subgrains, fragments) of the α-Zr matrix phase and β-Nb particles. This is a consequence of the recrystallization processes, which gives rise to softening of the alloy and a decrease in their microhardness and yield stress. It is found out that an annealing treatment for as long as 360 hr does not affect the structural element size of β-phase in the Ti – 45 wt.% Nb alloy but favors a noticeable grain growth in α- and ω-phases. It is demonstrated that disordering of the Ti – 45 wt.% Nb alloy and a decrease in its mechanical characteristics are due to the recovery processes at the grain boundaries, an increase in the nanosized grains of α- and- ω-phases, and their decreased contribution to dispersion hardening.

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

Based on the rules for summing oscillator-strength moments, we derive analytical expressions for environmentally (thermally) induced energy-level shifts and broadenings of circular Rydberg states with maximum orbital (l) and magnetic (m) quantum numbers, l = |m| = n – 1. The formulae for the energy of interaction with blackbody radiation are presented in the form of series expansion in even powers of the small parameter η = Z 2/(n 3 k B T) ≪ 1 in the region of high temperatures T and principal quantum numbers n (Z is the charge of the residual ion). The expression for the thermally induced width contains a negative temperature-independent term coinciding in absolute value with the spontaneous width, so that the temperature-independent term is absent in the expression for the sum of the spontaneous and thermally induced widths. A similar expansion in powers of η for the thermally induced shift also contains a temperature-independent term proportional to 1/n 6.

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.

The stage-like character of the stress-strain curves and microstructure in the fracture zone of coarse-grained and ultrafine-grained specimens of the VT1-0 and Zr–1Nb alloy specimens under quasistatic loading are investigated using the temperature curves obtained by the method of IR-imaging. New experimental data are obtained, which provide evidence on a considerable influence of the ultrafine-grained state on the evolution of plastic deformation and fracture in the VT1-0 and Zr–1Nb alloys.

Analytical expressions for spontaneous and induced by blackbody radiation energy shifts and widths of atomic circular states are derived. The features of asymptotic behavior of the total width and energy shifts for highly excited Rydberg circular states in the blackbody radiation field are described. Approximate equations are proposed for simple evaluations of energy characteristics and an absence of temperature-independent spontaneous contribution to the total energy width in a range of high temperatures and principal quantum numbers is demonstrated.

Analytical expressions are obtained for the constants determining the energy of the long-range (at large distances exceeding the LeRoy radius R LR ≈ 4n 2) polarisation interaction of the multipole electric moments of two atoms in identical Rydberg states with large principal (n) and maximum orbital (l) and magnetic (m) quantum numbers (|m| = l = n − 1). Asymptotic expansions in powers of n are found for the components of the van der Waals interaction tensor, which determine the dependence of the dispersion energy on the orientation of the interatomic axis. The spontaneous and thermally induced broadenings of the energy levels of circular states are represented analytically as functions of the principal quantum number and temperature. It is found that analytical formulae for the sum of spontaneous and thermally induced line widths in the region of high temperatures and large principal quantum numbers (assuming n 3 k B T >> 1) do not contain a temperature-independent contribution of the spontaneous part of the broadening. Closed analytical expressions are also obtained for the Farley − Wing function and for the n- and T-dependent corrections to the asymptotic behaviour of the thermally induced shift.

In this paper, we experimentally studied the limiting conditions for the combustion of hydrogen, methane, and propane in mixtures with air or oxygen at pressures below atmospheric. A significant effect is shown for the size of the reaction vessel and the ignition energy on both the minimal pressure value and the change in the concentration range of flame propagation. The dimensions of the reaction vessel and the magnitude of the ignition energy, the increase of which does not lead to a change in the minimal pressure and concentration region of flame propagation, are established. The minimal pressures Pmin of gas mixtures, below which flame propagation is impossible, were determined. A qualitative interpretation of the data is presented.

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 results of investigation of the influence of the structural element size and phase state of the Ti – 45 wt.% Nb and Zr – 1 wt.% Nb binary alloys on their mechanical properties are presented. The structural states of the alloys with the structural elements of different dimensions were formed from the ultrafine-grained state via annealing. The curves of dependence of the yield strength and microhardness on the average size of the structural elements, d –1/2, are obtained using the Hall–Petch relation. It is shown that for the Zr – 1 wt.% Nb alloy, the Hall–Petch relation is fulfilled in the entire range of sizes under study, from ultrafine-grained to finegrained states 0.2–1.9 μm. For the Ti – 45 wt.% Nb alloy, in the analysis of the Hall–Petch relationship within the structural element size range 0.43–45 μm, its phase composition is taken into consideration, specifically, the presence of dispersion-strengthened β-phase grains, α-phase subgrains, nonequilibrium nanosized ω- phase, and the bimodal grain-subgrain structure.

The characteristics of microstructure, deformation and fracture of Zr – 1 wt% Nb and Ti – 45 wt% Nb bioinert alloys in the coarse- and ultrafine-grained states are investigated. It is shown that the ultrafine-grained structure formed in them ensures excellent mechanical properties of the alloys and affects the stages of the stress-strain curves and the behavior of the maximum temperature vs. deformation time plot. The formation of an α-phase in the Ti – 45 wt% Nb ultrafine-grained alloy suppresses the linear stage VI characterized by a constant strain hardening coefficient. In stage VII, the strain hardening coefficient rapidly becomes negative, which indicates the material softening prior to its failure.

Ti–Nb alloy with 40 wt % of Nb is obtained from a composite Ti–Nb powder by means of selective laser melting. The Ti–Nb alloy has a two-phase microstructure. The main β-phase of the solid titanium–niobium solution forms grains ranging in size from ~2 to 20 μm. A nonequilibrium α″-phase is found in the forms of lamellar, globular, and packet martensite inside the grains of the β-phase and along their boundaries.

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.

Experimental data of thermal stability of the microstructure and mechanical properties (exemplified by the microhardness tests) of the ultrafine grained (UFG) Ti–45 wt % Nb alloy after long-term thermal influence were presented in the paper. UFG structure in the alloy was formed with the severe plastic deformation (SPD) method. It was proved that the SPD method including the multiple abc-pressing and multi-pass rolling and further pre-recrystallizing annealing enhances the formation of UFG structures with the mean element size of 0.25 µm. Samples of Ti–45 wt % Nb alloy in UFG state were annealed at 350 and 400°C during 1, 5, 10, 24, 120, 240 and 360 hours. It was shown that the UFG structure was stable after annealing at 350 and 400°C as a result of thermal influence within the time range up to 360 hours. Stability of mechanical properties depended on the temperature and duration of annealing, i.e. microhardness of 3200 MPa was remained during 120 hours of annealing at 350°C, while microhardness of 3000 MPa was remained during 10 hours of annealing at 400°C.

The evolution of the microstructure and mechanical properties (for example, microhardness) of biodegradable alloy Mg−0.8 wt % Ca after multi-pass rolling in grooved rollers at different accumulated strain values e = 0.4, 0.9, 2.0 was investigated. As a result of multi-pass rolling under cumulative deformation e = 2.0, the recrystallized structure with average grain size of 1.4 µm and ultrafine grain volume ratio of up to 35% were formed in the alloy. It was proved that the absence of alloy strengthening after rolling was associated with the fact that the strengthening due to grain size refinement was compensated by annealing, as a result of dynamic recovery. This also resulted in further redistribution of the phase composition with decreasing volume ratio and Mg2Ca particle dispersion.

Phase composition and microstructure of Ti–Nb alloy produced from the composite titanium and niobium powder by selective laser melting (SLM) method were studied in the present research. Ti-Nb alloy produced by SLM is a monolayer and has zones of fine-grained and medium-grained structure with homogenous elemental composition within the range of 36–38 wt.% Nb. Phase state of the alloy corresponds to the main phase of β- solid solution (grain size of 5–7 μm) and non-equilibrium martensite α″-phase (grain size of 0.1–0.7 μm). Grains of the α″-phase are localized along the boundaries of β-phase grains and have a reduced content of niobium. Microhardness of the alloy varies within the range of 4200–5500 MPa.

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.

In present paper Ti-Nb alloys produced via high-energy powder metallurgy method were studied. Ti-Nb alloys were obtained in form of layers on Ti substrate. The energy source was an electron beam emitted to the atmosphere, penetrating into deep layers of the powder. Electron energy was 1.4 MeV. It is shown that it is possible to produce alloys with predictable elemental and phase compositions via relativistic electron beam. Depending on the content of Nb, such phases as α′, α″ or β are formed. Produced alloys are non-toxic for cells. Due to this, manufacturing of small medical implants from this material is possible.

This paper focuses on the development of the microstructure and mechanical properties of bioinert Ti-40 wt.% Nb alloy after severe plastic deformation. Primary Ti40Nb cast billets were exposed to a combined two-stage severe plastic deformation method, including abc-pressing and multi-pass rolling in grooved rollers. It was proved that a relatively large amount of micron grains and subgrains were produced from the alloy through severe plastic deformation (SPD) method. Local shear zone, twins and low-angle grain boundaries were created in meantime. The misorientation angles of less than 6.45° constitutes 53.8 % of the alloy. SPD method intensified the formation of ultrafine-grained structure in Ti40Nb billet bulk with average element size of 0.3 µm. This, in its turn, improved the material strength. Microhardness of the alloy increased from 1730 MPa to 3000 MPa.

Results of analyzing the overall balance of materials, the oxygen balance, and the thermal balance within a 120-t arc smelting furnace are presented. It is found that the heat influx in the oxidation of iron and other batch components is so great that the thermal conditions and the process as a whole become autogenous. The significant losses in complete chemical combustion indicate unsatisfactory organization of the aerodynamic fluxes within the furnace. The aerodynamic fluxes and temperature fields in the region of the cold batch between the electrodes and the inner surface of the furnace wall are discussed on the basis of SolidWorks Flow Simulation software. Recommendations are made regarding the configuration of the gas–oxygen burners, the oxygen lances, and the units for injection of the carbon-based materials into the bath.

The microstructure and mechanical properties of bioinert titanium, zirconium, and niobium alloys in the ultrafine-grain state are investigated. The ultrafine-grain structure is obtained by severe plastic deformation, including multicyclic abc pressing at specified temperatures, multipass rolling in shaped rollers at room temperature, and low-temperature non-recrystallizing annealing. Annealing increases the plasticity of the ultrafine-grain alloys, without changing the grain size. As a result of two-stage treatment—severe plastic deformation and annealing—ultrafine-grain structure with grains and subgrains of mean size 0.16–0.25 μm is formed. That considerably improves the mechanical properties (ultimate strength, yield point, and microhardness) of the alloys. At the same time, the formation of ultrafine-grain structure in the alloys does not change the elastic modulus, even with considerable increase in the ultimate strength and plasticity.

The temperature distribution in the working space of an electric-arc steelmaking furnace built by the company “Danieli” and equipped with radially positioned fuel-burning devices is analyzed. It is concluded that the temperature field is quite nonuniform, and the suggestion is made to reposition the gas-oxygen burners into a tangential configuration. Computer modeling is used to determine the temperature distribution in the furnace’s working space for radially and tangentially arranged burners.

Results are presented from an analysis of the motion of gas flows created by fuel-burning devices in existing electric-arc steelmaking furnaces and recommendations are made on how to efficiently arrange this equipment in the furnace. Controlled annular motion of the aerodynamic flows in the part of the working space between the furnace wall and the electrodes increases convective heat transfer to the cold solid charge, forms a reliable and uniform slag crust on the water-cooled wall, and alleviates the deposition of process dust on the electrodes. A numerical study is performed using the SolidWorks Flow Simulation program and boundary conditions that reflect the actual operating conditions in the furnaces.

Total probabilities Anl of spontaneous radiative transitions, which determine lifetimes τnl = 1/Anl of nS-, nP-, nD- and nF-states in singly charged ions of the group IIa (Be+, Mg+, Ca+, Sr+, Ba+) and IIb (Zn+, Cd+, Hg+) elements, were calculated in the single-electron Fues’ model potential (FMP) method. An asymptotic dependence is determined for highly excited states with small angular momentums and presented in the form τnl = τl(0)n3Ql(1/n) and numerical values of the factors τl(0) and coefficients of the cubic polynomial Ql(x) are calculated, which approximate results of numerical computations with relative error below 2% in the range of states with principal quantum numbers from n = 7 to n ≈ 2000. The comparison of the numerical results with data in literature is presented, and applicability and reliability of single-electron model calculations are discussed in detail for positive singly charged ions of the group II elements.

The paper presents the experimental data observed in the microstructure and phase composition of ultrafine-grained Ti–40 mass % Nb (Ti40Nb) alloy after high-temperature annealings. The ultrafine-grained Ti40Nb alloy is produced by severe plastic deformation (SPD). This method includes multiple abc-pressing and multi-pass rolling followed by further pre-recrystallizing annealing which, in its turn, enhances the formation of ultrafine-grained structures with mean size of 0.28 µm involving stable β- and α-phase and metastable nanosized ω-phase in the alloy. It is shown that annealing at 500°C preserves the ultrafine-grained structure and phase composition. In cases of annealing at 800°C the ultrafine-grained state transforms into the coarse-grained state. The stable β-phase and the nanosized metastable ω-phase have been identified in the coarse-grained structure.

The synthesis of 1-[(2-R-o-carboran-1-yl)methyl]benzotriazoles (R = Me, Ph) is described. α-Deprotonation of these compounds followed by reactions of the generated carbanions with MeI give the corresponding α-methylated products. Even at room temperature, they exist in solution as an equilibrium mixture of two conformers due to steric crowding around the Cα atom. In contrast, the anions generated by deprotonation of α-ferrocenyl derivatives of 1-methyl- and 1-ethylbenzotriazoles are ambident and are attacked by electrophiles at both the Cα and N(3) atoms.

Blackbody-radiation-induced transitions from Rydberg states in S-, P-, D-series of neutral potassium are investigated at temperatures T = 100 - 2000 K . Key features of such transitions are described. The improved approximation for rates of blackbody-radiation-induced decays and excitations from Rydberg states is proposed with an adaptation for wide range of temperatures.

General properties were determined and asymptotic approximation formulas for probabilities of spontaneous decay and photoionization cross-sections were derived on the basis of numerically calculated amplitudes of bound-bound and bound-free radiation transitions from Rydberg nS-, nP- and nD-states of alkali atoms with high principal quantum numbers, up to n = 1000. The departure of data from the asymptotic formulas for states with principal quantum numbers in the range between n = 10 and n = 2000 from originally calculated data does not exceed 0.1–1%, and may be useful for estimations of natural radiation widths for arbitrary high Rydberg levels.

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 LTRretrotransposon gtwin of Drosophila mel� anogaster was first cloned from the laboratory strain G�32, which is characterized by a strong amplification of copies of this transposable element (1). In addition, strain G�32 has a number of other unique features, such as the presence in the majority of studied species of a complex extended inversion in the third chromo� some, within which gtwin insertions are accumulated (2), as well as an increased frequency of occurrence of singlestranded DNA breaks, which cause recombina� tion processes and gene conversion (3). Currently, gtwin transpositions in strain G�32 are not observed; however, extrachromosomal circular copies of this ele� ment containing two polymorphic sites in the binding sequence of the tRNA primer for the synthesis of the minus strand of DNA were identified in the genome. Among the analyzed clones containing relevant 5'� untranslated region of circular gtwin molecules, the group with a mutant binding site for the tRNA primer represented by noncomplementary nucleotides at positions 497 and 503 was found to be the most numerous. In addition, four fulllength gtwin copies cloned from the genomic library of strain G�32 also belonged to the subfamily with the "incorrect" bind� ing site for the tRNA primer (4). In this work we performed molecular analysis of different copies of LTR retrotransposon gtwin, which were cloned from strain G�32, and showed that, although its genome contains variants with either nor� mal or mutant binding site for the tRNA primer for the synthesis of the minus strand of DNA, it is the mutant subfamily that was amplified. In addition, we searched different gtwin variants in 14 laboratory strains of D. melanogaster and in D. melanogaster Schneider 2 cells. We demonstrated the existence of two subfam� ilies of the

Regioselective bromination of 14β-hydroxydihydroquinopimaric acid methyl ester in acetic acid and methanol gave the corresponding 16S-bromo-, 19R-bromo-, and 16S,19R-dibromo-14β,20-epoxy derivatives whose structure was determined by X-ray analysis and NMR spectroscopy. The reactions of 16S-bromo ketones with thiourea afforded 2,1,3-thiadiazoles fused to diterpene fragment.

Direct aromatic C—H bond activation in the (Sa)-BINOL-derived phosphite (Sa)-HL afforded the dimeric cyclopalladated complex (Sa,Sa)-{Pd(η2-L)(μ-Cl)}2 (2) which is the first optically active PC-palladacycle bearing a phosphorus atom in an axially chiral environment. ortho-Palladated structure of dimer 2 was confirmed by spectral (1H and 31P NMR) examination of its mononuclear derivatives and by X-ray diffraction analysis of the phosphine adduct (η2-L)PdCl(PPh3) (4). The enantiomeric purity of the starting ligand remained unchanged in the PC-palladacycle under the thermal conditions used for the cyclopalladation (∼110 °C); this fact was confirmed by the 31P NMR spectroscopy after chiral derivatization in situ of dimer (Sa,Sa)-2 with the (RC)-valinate chiral auxiliary (Val). trans(N,C)-Configuration of the valinate complex (η2-L)Pd(Val) (5) was established by 1H NMR and supported by DFT calculations. The chirality transfer in the new PC-palladacycle was discussed on the basis of X-ray diffraction data for the phosphine adduct rac-4 and DFT calculations performed for both phosphine and valinate mononuclear derivatives.

The rare olean-18(19)-ene triterpenoids moradiol and moronic acid were synthesized from betulin, and their antiviral properties were investigated.

42 Mobile genetic elements account for a considerable part of eukaryotic genome and significantly affect its stability. They are involved in mutagenesis, regulation of gene expression, and occurrence of genomic rearrangements. In view of this, the study of the mechanisms by which the activity of transposable elements is regulated by cellular factors is of great interest. For this purpose, it is convenient to use model objects in the genome of which mobile genetic elements are transposed and amplified. The behavior of mobile genetic elements in different Drosophila species has been described sufficiently well so far. There are many Drosophila strains characterized by genetic instability caused by amplification and transposition of mobile genetic elements. In such strains, an increased frequency of mutations and reversions as well as occurrence of chromosomal rearrangements is observed. A characteristic feature of D. melanogaster laboratory strain G32 is unusual behavior of some mobile elements. In particular, this strain characterized by substantial amplification of the gtwin retrotransposon, which is closely related to gypsy , one of the most comprehensively studied mobile genetic elements. Evidences indicating that currently gtwin undergoes transpositions have not been obtained [1]. In addition, we detected a large chromosomal aberration in this linea with an increased number of sites where gtwin and some other mobile genetic elements are located [2]. It is known from published data that mobile genetic elements are inhomogeneously distributed over the genome, which leads to occurrence of clusters playing a major role in the regulation of transposition activity [3]. Taking into account this information and the fact that the number of gtwin copies in the G32 strain was approximately 30 (which is one order of magnitude larger than the commonly detected number of copies of this element), we assumed that different gtwin copies may be located in the immediate vicinity of one another. In this study, we tested a series of D. melanogaster strains for the presence of neighboring gtwin copies by PCR using genomic DNA as a template. The annealing sites for PCR primers were located at both ends of gtwin in the vicinity of its long terminal repeats (LTRs). Synthesis proceeded in the direction of the genomic environment of the element.

A determination of enantiomeric purity of 1-substituted (Me, Ph, and Pri) 3-amino-1,2dicarba-closo-dodecaboranes by HPLC on chiral Chiralcel OD-H and Chiralpac AD stationary phases involving preliminary phthaloylation of 3-aminocarboranes has been suggested as a general method.

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 structure of Ti-40Nb alloy prototype obtained by selective laser melting (SLM) on “VARISKAF 100MV” installation was considered by the methods of optical metallography, scanning and transmission electron microscopy. It was revealed that the most of the specimens’ surface is uniform flowed surface with typical banded structure formed by laying-on molten pools. The process of the individual layer formation was followed by drop formation. This leads to the porosity formation on the specimen’s surface. The structure of entire specimen is not homogeneous throughout the transverse section. The porosity of three kinds is observed. They are cavities of not full contact and melting of the layers, drawholes, gas pores. The porosity optimization requires more careful SLM modes selection. The alloy has a grain structure with anisotropy from small (2–8 µm) to medium (8–20 µm) grain size. The anisotropy of the specimen is formed in each layer and is retained during building of the specimen. The grains of microstruct...

A retrotransposon of the Mag family was found in the Drosophila simulans genome for the first time. We also identified novel transposable elements representing the Mag family in seven Drosophila species. The high similarity between the 3' and 5' long terminal repeats in the found copies of transposable elements indicates that their retrotransposition has occurred relatively recently. Thus, the Mag family of retrotransposons is quite common for the genus Drosophila.

A consecutive aromatic nucleophilic substitutions of hydrogen in 1,2,4-triazine 4-oxides and an aza Diels−Alder reaction is a versatile route to carborane-functionalized bi- and terpyridines and their 1,2,4-triazine analogues. The heterocycles facilitate deboronation of the substituted carboranes, and the carborane moiety has a significant influence on the coordination properties of the ligands as well.

The reactions of 1-lithia-1,2- or 1,7-dicarba-closo-dodecaborane with 1,2,4-triazine 4-oxides can follow two competitive pathways: deoxygenative nucleophilic substitution of hydrogen to form 1-(1,2,4-triazin-5-yl)-1,2- or 1,7-dicarba-closo-dodecaboranes and the transformation of the 1,2,4-triazine ring into the triazoline ring giving rise to 1-(2-acetyl-1-aroyl-3-aryl-1,2,4-triazolin-5-yl)-1,2-dicarba-closo-dodecaboranes. Introduction of the electron-withdrawing triazine ring into the carborane cage substantially facilitates deboronation to give 1-(1,2,4-triazin-5-yl)-1,2-1,7-dicarba-nido-undecaboranes.

Theoretical analysis is presented of the natural lifetimes and blackbody-radiation (BBR)-induced shifts and widths of Rydberg states with small and large angular momenta l. Asymptotic presentations in elementary functions are derived for matrix elements of bound-bound, bound-free and threshold radiative transitions from hydrogenic-type states with large angular momenta, applicable to both hydrogen-like and many-electron atoms and ions. For states with small angular momenta two numerical methods based on the quantum defects were used and corresponding data are compared with one another and with the most reliable data of the literature. Asymptotic approximations are derived for natural lifetimes, thermal shifts and broadening of Rydberg states of small and high l and principal quantum numbers n ≫ 1.