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The article provides an overview and analysis of seismicity within the boundaries of the Arctic region for 2016–2017, a description of seismic station networks, and processing methods. The catalog of earth-quakes in the Arctic region was compiled on the basis of catalogs of several organizations and seismological centers. In total, 875 earthquakes are included in the earthquake catalog. Most of the earthquakes that occurred in 2016–2017, including all the strongest earthquakes, were located within the mid-ocean ridges of Mon, Knipovich. and Gakkel. In the offshore territories, most of the earthquakes were confined to the Svalbard archipelago, in particular, to the seismically active zone in the Sturfjord strait. Within the shelf areas, seismicity is also character-istic of the "continent-ocean" transition zone of the Barents-Kara region. Most earthquakes within the transition zone are confined of the trenches. For 39 earthquakes, the focal mechanism parameters are presented according to the Global CMT catalog.

In this paper, we consider the method of generating gravitational waves by means of a system of standing electromagnetic waves at the difference frequency in electromagnetic resonators and their further registration based on various types of detectors. As a factor of amplification of the amplitude of gravitational waves induced by the proposed method, the inverse dependence of their amplitude on the square of the difference frequency is considered, which is a consequence of Einstein’s equations for the studied configuration of electromagnetic fields in the resonator. The characteristics of gravitational waves associated with the electromagnetic field inside the resonator and gravitational waves in empty space are compared. The possibility of conducting an experiment on the generation and detection of gravitational waves with controlled parameters of the source and detector (Hertz experiment) on the basis of the proposed method has been investigated. Various types of existing and promising detectors of low-frequency gravitational waves are considered and an estimate of the source characteristics necessary for the successful detection of gravitational waves generated by this method is obtained. The effectiveness of the proposed approach is compared with other methods of generating gravitational waves. The specificity of the considered method of generating gravitational waves is noted, associated with the possibility of obtaining in laboratory conditions low-frequency gravitational waves with a frequency close to the frequency of gravitational waves of astrophysical sources and the amplitude significantly exceeding the amplitude of high-frequency gravitational waves, which can be generated on the basis of previously proposed methods

The paper presents long-term measurement results concerning the Kullback --- Leibler divergence variations for electric current fluctuations in electrolytic cells and relative dispersion variations for electric current fluctuations in tunnel diodes. It is possible to transition from investigating current fluctuations in electrolytic cells to measuring similar fluctuations in tunnel diodes due to the charge carrier mass in diodes being considerably lower than masses of electrolyte ions. This decrease in mass leads to an increase in the sensitivity of the experimental installation. We found that the magnitude spectrum of Kullback --- Leibler divergence variations has a maximum corresponding to a period of 25.25 days (606 h). As for the magnitude spectrum of relative dispersion variations, its maximum is observed at the signal period of 25.88 days (621 h). These periods are close to the sidereal period of the Sun, that is, 25.38 days (609 h). We propose to use tunnel diodes with high peak current values and high direct forward voltage applied in order to increase the sensitivity of the experimental installation

The study centers around the possible existence of high-frequency relic gravitational waves, focuses on specialized gravitational antennas necessary for their registration, and proposes to use low-frequency optical resonance laser gravitational antennas. Within the study, we calculated the sensitivity of the Fabry --- Perot interferometer, which uses the phenomenon of low-frequency optical resonance, and obtained formulasto describe the radiation transmitted by the Fabry --- Perot interferometer and the spectral density of the response to the action of a gravitational wave. The study reveals the possibility of registering relic gravitational waves in the high-frequency part of the spectrum, and estimates the limiting sensitivity of a laser gravitational antenna. Findings of the research show that the main factor limiting the sensitivity of a laser gravitational antenna is photon noise. To reduce the contribution of photon noise, we propose to significantly reduce the power of laser radiation transmitted through the Fabry --- Perot interferometer, which can be achieved using low-frequency optical resonance. We estimated the required power of the radiation transmitted through the interferometer to achieve the limiting sensitivity of the laser gravitational antenna. The mathematical modeling confirmed the presence of low-frequency optical resonance in the high-frequency part of the radiation spectrum that passed through the Fabry --- Perot interferometer. We found that in the high-frequency region the resonant response exceeded by 2 orders of magnitude the non-resonant effect on the Fabry --- Perot interferometer

Methylene blue is known for a wide spectrum of biochemical activity: being reversibly oxidized and reduced, it acts as a hydrogen carrier and can be considered as a model of the active group of the enzyme dehydrase. When harmonic vibrations with a frequency of 7--30 Hz are introduced into an aqueous solution containing methylene blue and ascorbic acid, the kinetics of redox transformations changes: the kinetic dependences of the influence of the acoustic vibrations differ from the data obtained in the absence of low-frequency influences. Under certain conditions, effects such as acceleration and inhibition of the sonochemical process are observed. The paper studies the reaction of hydrogen transfer in the field of low-frequency oscillations. The purpose of the study was to elucidate the role of factors accompanying the effect: we determined the influence of oxygen, the emerging radical forms of methylene blue, and ascorbic acid. By absorption spectroscopy and EPR spectrometry, we specified the parameters of the compounds formed at the intermediate stages of the methylene blue reduction process. Relying on experimental data, we introduce a method for countering the COVID-19 virus using methylene blue

The paper uses the example of the Brownian motion to kinetically describe the process of entropy increment in a nonequilibrium medium. The study shows that depending on the degree of nonequilibrium, the convergence to an equilibrium state occurs according to different laws. In the case of a strongly nonequilibrium medium, the entropy increment is described mathematically by the weakest logarithmic law, and in the case of a close-to-equilibrium medium, the entropy seeks a maximum value according to the strongest mathematical law --- the exponential law. The obtained expressions describing the Brownian motion can be extended to all other nonequilibrium processes. Mathematical modeling made it possible to calculate the process of entropy increment for an arbitrary degree of nonequilibrium and establish the parameters at which the transition from logarithmic to exponential law of entropy increment occurs when the thermodynamic system seeks an equilibrium state

The study statistically describes Brownian motion in a locally nonequilibrium medium, taking into account the production of entropy, and proposes to describe the nonequilibrium fluctuations of the velocity of a Brownian particle using a linear integro-differential equation. The characteristic functions of fluctuations of the Brownian particle velocity are obtained, which make it possible to carry out a complete statistical description of Brownian motion in a medium with the production of entropy. Findings of research show that the variance of these fluctuations increases with time according to the logarithmic law. The correlation function of fluctuations of the Brownian particle velocity is calculated and it is shown that it consists of two terms. The first term, which has a power-law dependence, describes equilibrium fluctuations, and the second, which has a logarithmic dependence, describes nonequilibrium fluctuations

According to generally accepted international standards, the characterization and confirmation of the quality of biological pharmaceutical substances requires the use of not only a combination of physicochemical and biological tests, but also an in-depth knowledge of the production process and its control. The study of such an industrial process involves considerable expenditure of time and material resources. Gaining a deep knowledge of the production process is greatly facilitated by using laboratory models of industrial installations that effectively reproduce large-scale processes in a research laboratory. On the basis of a laboratory bioreactor for the cultivation of eukaryotic cells with a working volume of 2 L, a scale-down model of a pilot bioreactor has been developed, linearly scalable to a production volume of 1000 L. The laboratory model reproduces the key parameters of cultivation on a pilot scale: the ratio of the geometric dimensions of the reactor, the peripheral speed of the mixer, the specific power input, the coefficient of oxygen mass transfer, the type and intensity of aeration, strategies for defoaming, feeding and maintaining the pH level. Experiments using the developed model showed high similarity in the kinetics of cell growth, productivity and quality of the expressed monoclonal antibodies in laboratory and pilot bioreactors. Key words: cultivation, CHO cells, monoclonal antibodies, scale-down model

The paper describes the process of generating a coupled gravitational wave as a result of two electromagnetic waves propagating in a vacuum, the frequency of one wave being two times that of the other. We show that when a coupled gravitational wave interacts with two strong electromagnetic waves, lower frequency harmonics are generated. We consider the case of generating a coupled standing gravitational wave by means of strong standing electromagnetic waves and recording said gravitational wave as it interacts with these electromagnetic waves. We determined that the sensitivity of modern SQUID magnetometers is adequate for successfully conducting a laboratory experiment in generating and recording coupled high-frequency gravitational waves.

The failure of high-power synchronous motors leads to significant financial losses. This is of great importance for synchronous generators operating in high-power electrical networks and having an effect on a great many consumers. Sudden failure of the high-power generator results in heavy fines and repair costs, malfunction of the power-supply systems, and electric users. Troubleshooting of the equipment is aggravated by many interrelated factors. The method of measuring the external electromagnetic fields, which is widely used for the induction motors, is not used in practice for synchronous machines. Installation of field sensors inside the synchronous machine is not always possible, and measurement of external fields has weak methodological and factual bases. Simulation of the synchronous machine allows tracing the connection of a particular defect with the distortion of the external electromagnetic field of the machine. Full-scale experiments show the actual feasibility of measuring the magnetic fields in the off-synchronous generator housing. Investigation of an external electromagnetic field’s connections with specific machine defects, development of field measuring procedures and processing of the measurement result, and uncovering the diagnostic properties characterizing the state of an operating synchronous machine and allowing making a required decision, is an important scientific and technical issue.

The paper presents a method of describing Brownian motion in a non-equilibrium medium for the case of irreversible processes. We computed spectral density of velocity fluctuations for a Brownian particle in a non-equilibrium medium and determined that in the low-frequency region it is represented by flicker noise. We employed the method we developed to describe Brownian motion in a non-equilibrium medium to compute fluctuations of current in a small volume of an electrolyte. We derived estimations of the Hooge parameter magnitude and the randomisation time constant for ions in an electrolyte, which match the estimations obtained via experiments

Sub-nanosecond luminescence of Mn2+ in Mn-, Sn/Mn-, and Cu/Mn-doped Li2B4O7 ceramics is observed under laser excitation. Picosecond pulsed laser radiation (350–370 nm) generates the frequency-doubled radiation directly in a single microcrystal selected in a ceramic sample, with this secondary radiation falling within the impurity-induced VUV excitation bands of doped Li2B4O7. These excitation bands are attributed to the creation of an impurity-bound intra-anionic exciton in MeiO4–BO3–MnLi complex centres (Mei = Mn, Sn, or Cu). The exciton, in turn, interacts with a nearby Mn2+ ion due to mixing of the Mn2+ excited states with the excitonic states. Exciton annihilation involves Mn2+ energy levels as transient states and causes a sub-nanosecond radiative transition which is accelerated, being accompanied by rearrangement of the surrounding atoms. Excitation within the lower-energy bands is related to the other part of the complex luminescence centre, this is metal-to-ligand intra-anionic charge transfer, which makes an electron accessible to MnLi, while the hole is transferred only during relaxation of the excited structure. Mn2+ radiative transitions are not forced in the latter case, and slow Mn2+ luminescence decay is observed.

A systematic approach to characterizing the cell culture process of CHO-producers of monoclonal antibodies within the framework of the concept "Quality by design" (QbD) with the use of ambr15 mini-bioreactors (TAP Biosystems) is shown.

The results of measurements carried out in summer, 2007 in the north-western part of the Barents Sea are discussed. The ship weather station and the vessel mounted Acoustic Doppler current profiler VMADCP150 are used to carry out measurements in the vessel motion. CTD/LADCP-sensing is performed at the drift stations. The minimum horizontal scale of a temperature front is 0.5 km, whereas the maximum horizontal gradient of water temperature is 4 °C/km. The width of the North Cape Current Northern branch is ~8 km that is three times larger than the Rossby radius of deformation. Position of the temperature front coincides with that of the jet stream core. The characteristics of small-scale vertical structure of water dynamics and density stratification in the polar frontal zone are discussed. The averaged annual variability of temperature and salinity vertical structure in the area of the Spitsbergen Bank and the Hopen Deep are represented. The intra-annual variability of water salinity in the Hopen Deep calculated based on the historical database of hydrological data, revealed the presence of variations with a period of four months. Based on satellite observations, position of the temperature front in the area of research is defined.

The article presents the core results of lowered acoustic Doppler current profiler (LADCP) applied in the Black Sea within 2004–2014. Average features of the vertical structure of currents in the upper 600 m layer are outlined. The linear relation between vertical distribution of kinetic energy isopycnically averaged over the station ensemble and density is established. This relation is traced till the isopycn occurrence depth with density of 17 kg/m3 (500 m). The mean current velocity has near constant value about 4 cm/s in lower depth layers (>500 m), which is in a good agreement with autonomic buoys data. The averaged profile of current velocity vertical shears shows two well- separated maxima in the seasonal and main pycnocline layers. LADCP derived velocity shears are more than ten times exceed the geostrophic current shears. Turbulent vertical mixing coefficient, calculated by the G89 model (Gregg 1989) demonstrates the denominated minimum in the permanent pycnocline (4∙10-6 m2/s) and increases with depth to achieve value 2∙10-5 m2/s at 450 m depth. The profile of current velocity averaged by the ensemble casts in the near bottom boundary layer demonstrates near logarithmic relation.

Hydrogen exchange experiments reveal the existence of a foldon structure in Cytochrome c. We performed constant temperature Molecular Dynamics simulations of Cytochrome c to investigate the macroscopic behavior of the foldons. The results showed that the tertiary interactions in Cytochrome c play an important role in the stabilization of the N- and C-terminal helices. We also observed the macroscopic behavior of a black foldon in the process of thermal unfolding. Our results support that Cytochrome c folding occurs in accordance with the classical pathway concept of Levinthal.

The most probable parameters of the pure, doped, and mixed GaSe1−xSx (x ≤ 0.4) crystals (solid solutions) are presented together with the results of investigations of their crystal structure and defects, optical and mechanical properties, and damage thresholds.

Real defect structure, growing technology and physical properties of doped GaSe:S crystals are presented. From comparative experiment on CO 2 laser SHG at identical experimental conditions 1.45 times advantages of GaSe:S (2 wt%) in relation to pure and GaSe:In (0.1 wt%) crystals are developed.

Structural transformations in nickel films exposed to N+ ions were investigated through the use of electron diffraction, electron microscopy, Rutherford backscattering (RBS) of He+ ions, thermal desorption spectroscopy (TDS). With an increasing exposure dose, there occurred a smooth transition of the FCC structure of Ni to the HCP phase α-Ni3N with the lattice parameters a=0.266 nm and c=0.430 nm . The completion of the transition was observed once the implanted nitrogen concentration corresponding to the stoichiometric ratio of Ni3N was attained, this giving evidence for the chemical nature of the structural change observed. During annealing, structure variations were traced, enabling one to observe the following four nickel nitrides: (1) α-Ni3N with a disordered arrangement of nitrogen atoms (HCP-phase with a=0.266 nm and c=0.430 nm ), (2) β-Ni3N with an ordered arrangement of nitrogen atoms (two hexagonal lattices: one with a=0.266 nm , c=0.430 nm , and the other with a=0.466 nm and c=0.43 nm ), (3) Ni4N having a primitive cubic lattice structure with a=0.377 nm , (4) Ni8N having the FCC structure with a=0.725 nm . The results of an investigation have led to building up a phase diagram for the Ni–N system.

In this study angular dependencies of type-I and type-II phase matching in pure and doped GaSe were applied for efficient identification of their polytype structure and structural features. In turn the express analysis of optical uniformity is performed by crystal incorporation into the SHG scheme as an attenuator of the pump beam.

Physical properties of Al-doped GaSe or GaSe:Al(0.01, 0.02, 0.05, 0.1, 0.5, 1, 2 wt%) crystals in charge composition were studied in comparison with pure GaSe to reveal the potentials for sub- and microwave elec-trooptical application. Aluminium was not detected in GaSe:Al by X-ray chemical analysis. It was found that resistivity of GaSe:Al drastically increases with Al doping up to 105−107 in comparison with (1–3)·102 in pure GaSe and 103 Om-cm in GaSe:S(2 wt%). No significant changes in optical properties to that in GaSe (α≤0.1–0.2cm−1) were found at 0.01–0.02 wt% Al-doping but 2-fold to 3-fold increase in hardness at 0.5 wt% Al-doping. GaSe physical properties modified by Al-doping make it very attractive for mid-IR and sub-microwave electrooptic applications.

The near IR and sub-microwave range optical properties of AgGaS 2 -doped GaSe (GaSe:AgGaS 2 ) grown in accordance with chemical formula [2(GaSe)] 1−x :(AgGaS 2 ) x , x=0.1, in charge composition, were studied in comparison with that in 2 wt% and 10.2 wt% S-doped GaSe (GaSe:S) to reveal the potentials for phase matching and frequency conversion from near IR into sub-microwave range by down-conversion of fs Ti:Sapphire laser emission. The composition of grown GaSe:AgGaS 2 crystal is identified as GaSe:S (2.19 mass%). The crystal possesses 25% higher hardness comparing to that of GaSe:S(2 mass%) grown by traditional technique, can be cut and polished, and is useful in applied systems. It was found that GaSe:S possesses the best set of physical properties for sub-microwave and microwave generation among doped GaSe crystals.

Microdefects in dislocation-free Si-doped (n = (1–3) × 10 18 cm -3 ) HB GaAs crystals were studied by X-ray diffuse scattering measured with the help of a triple-crystal diffractometer. The intensity of the diffuse scattering as well as the isointensity contours around different reciprocal lattice points were analysed. A comparison of the measured isointensity contours with the theoretically calculated ones showed that the microdefects detected are interstitial dislocation loops with the Burgers vectors b = 1 2 lying in the planes #38;{110} and {111}. The mean radius of the dislocation loops R 0 was determined using the wave vector q 0 alpha; R -1 0 corresponding to the transmition point where the Huang diffuse scattering I ( q ) alpha q -2 ( q q 0 ) changed to the asymptotic scattering I ( q ) alpha q -4 ( q #62 q 0 ). The analysis of a D-shaped cross-sectional (111) wafer cut from the end part of the HB ingot showed that R 0 changed smoothly along the [ 2 11] symmetry axis of the wafer. The highly inhomogeneous “new-moon”-like distribution of the non-dislocational etch-pits was also obtained. The maximal loop radius obtained at the edges of the wafer, R 0 = 1 μm , corresponds to the wafer area enriched with etch-pits and the minimal one, R 0 = 0.3 μm , corresponds to the bound of the new-moon-like area denuded from etch-pits. Microdefects of a new type were detected in the denuded area. These microdefects consist of nuclei, 0.1 μm in radius, and an extended atmosphere of interstitials. The minimal microdefect radius in the centre of the wafer corresponds to the maximum local value of the lattice parameter a = 5.655380 A , and the minimum local value a = 5.65372 A was obtained at the wafer edges enriched with microdefect-related etch-pits. Absolute X-ray diffuse intensity measurements were used for microdefect concentration determination. Normalization of I ( q ) was based on the comparison of the Huang intensity with the thermal diffuse scattering intensity which is predominant for the wave vector q a R -1 0 . The microdefect concentration determined in this way appeared to be 4 × 10 9 cm -3 at the edges of the wafer and 4 × 10 11 cm -3 at the centre of the new-moon-like etch-pit denuded zone. The number of interstitial atoms forming dislocation loops is shown to be the same across the area of the wafer and equal to 10 16 cm -3 .

Microdefects related to the small etch pit background in LEC and HB GaAs crystals undoped and doped with Si, Te, In and Zn were studied by triple-crystal diffractometer measurements of X-ray diffuse scattering and selective etching. The microdefects related to these nondislocative etch pits have never been revealed by TEM, in spite of their high density. The similarity of the X-ray diffuse scattering features in all the samples characterized by such an etch pattern makes it evident that all these crystals contain a high density of microdefects of the same crystallographic nature that can be considered as As self-interstitial aggregates having a nucleus of a finite size and long-range diffuse boundary with the GaAs matrix. The density and size of these microdefects varied from 10 7 to 10 11 cm −3 and from 0.1 to 0.5 μm, respectively. The computer simulation of the diffuse scattering associated with different crystallographic types of defects showed that the microdefects observed are {113}-planar interstitial aggregates surrounded by the extended atmospheres of native point defects and/or impurities.

GaSe 1−x S x single crystals has been grown by Bridgman-Stockbarger technique. Structural quality has been evaluated with TEM observation. Terahertz time-domain spectroscopy has been applied for measurements of the frequency-dependent optical constant of doped GaSe crystals as a function of s-content.

For prospective nonlinear crystals GaSe 1−x S x experimental study of second harmonic generation processes of Er3+:YSGG-, CO 2 - and CO-lasers has been performed, control experiment on difference frequency generation of two lines of CO 2 -laser has been realized, the transmission spectra and dispersion of complex refractive indices in terahertz range have been measured.

Thermodynamic calculations of homogeneity region of Sn-, Te- and Si-doped GaAs were carried out to analyse equilibrium and supersaturated native point defect behaviour during crystallization and postcrystallization cooling. Arsenic Frenkel, Schottky and antisite defects are included in the model with the Frenkel defects being dominating. Besides decomposition Ga- (or As-) supersaturated nonstoichiometric solid solution which takes place in the two-phase region of the phase diagram at temperatures below 800–1000°C, a great amount ( ≈ 1019cm-3) of arsenic vacancies and interstitials become overquilibric on postcrystallization cooling immediately after crystallization, which leads further to the high-temperature aggregation process. The great difference in point defect formation energies causes their transformation to each other and leads to significant decrease of increase of arsenic antisite concentration on cooling of Ga- or As-rich crystals respectively. Narrowing of low-temperature (850–1000°C) boundaries of GaAs homogeneity region on Sn and Si doping accomplished by a shift of congruent point to Ga-rich compositions stimulate Ga-supersaturated nonstoichiometric solid solution decomposion. The so-called superdilation phenomena may be due to the great amount of gallium interstitials formed at the very initial stage of the decomposition. Te-doping shifts GaAs homogeneity region to the As-rich compositions and makes lateral surfaces of existence region to twist around the axis of elongation of the latter.

This paper presents the results of investigation on influence of doping with sulfur and annealing in sulfur atmosphere on properties of promising nonlinear optical gallium selenide crystals, grown by the Bridgeman method from melts with content of sulfur 0.01-3 mass % and annealed in sulfur atmosphere.

In spite of the progress in GaSe growing technology (high-quality crystals grown by the latest technology are characterized by low values of optical losses with the absorption coefficient values lying below 0.1 cm−1) the work continues on improving crystal properties for nonlinear optical applications. This paper presents the results of investigations on the influence of annealing in a sulfur atmosphere and in a vacuum on the properties GaSe single crystals, grown by the Bridgman method from the melt. The objective of this work was to study the possibility of intercalating GaSe with sulfur from the gas phase, and to compare the influence of doping with sulfur from melt and vapor phase on the structure and properties of GaSe crystals. Three series of annealing experiments have been conducted at temperatures 773, 923, 1073 K and the samples obtained have been studied by Hall effect, photoconductivity, optical absorption, microhardness measurements and X ray diffractometry. The results obtained are explained by assuming the intercalating of sulfur to the interlayer space and substitution of Se with S.

This paper presents the results of investigations on the influence of sulfur doping on properties of gallium selenide crystals, grown by the Bridgman method from melts with sulfur content of 0.01–3 mass %, using the Hall effect, optical absorption, photoconductivity and microhardness measurements on GaSe: S. The results obtained are explained by assuming the formation of solid solutions of GaSxSe1−x and the presence of the competitive processes of point defects and structural disorder formation.

The theoretical and experimental results are presented which relate to flows over such simple bodies as a semisphere, a wedge, and a cone investigated in hypersonic wind tunnels of various classes at similar Mach and Reynolds numbers (M=7.0 to 8.0; Re/sub o//spl sime/135 to 210) and at different air flow velocities (790/sup m///sub s/, 2700/sup m///sub s/ and 6000/sup m///sub s/). Hypersonic resistor-type and arc-heating wind tunnels and a hypervelocity MHD-air acceleration wind tunnel, as well as their test equipment are described. Experimental data on pressure distribution on model surfaces, shock wave position and shape were obtained. For visualization purposes, an electron beam was used in the first wind tunnel and filming of natural flow glow was made by using neutral and interference light filters in the second and third wind tunnels. Use was also made of a specially developed shadow device based on the application of an abnormal dispersion effect of resonant emission of Na atoms. The experimental body flow data are compared with respective calculated results obtained by using the VSL theory and the Navier-Stokes equations. The data are in good agreement for the case of a perfect gas and satisfactory for the case of a gas with chemical reactions.