bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of Regional Atmospheric Circulation in Interannual Variability of the Ocean Heat Advection in the Nordic Seas
Authors: Iakovleva D. A , Bashmachnikov I. L.
Published: April 2024

More than 90% of oceanic heat enters the Arctic Ocean with the Norwegian Current. In this paper we examine the mechanisms of variability of the oceanic heat flux in the Norwegian Current (across the Svinoy section in the southern Norwegian Sea) in 1993–2019. GLORYS oceanic reanalysis with a spatial resolution of 1/12° is used. It is found that the variability of oceanic heat flux is associated with that of water transport, which, in turn, is associated with variability of the sea level gradient across the Norwegian Current. It is shown that an increase in water transport of the Norwegian Current is a result of a decrease of the atmospheric pressure over the central part of the Norwegian Sea. The latter intensifies the southwesterly winds along the Scandinavian Peninsula. The sea level gradients across the Norwegian Current, formed by the winds, are primarily associated with Ekman pumping towards the coast, as well as with the wind stress curl. Both have a significant impact on the variability of water transport through the section. Another factor is variability of the steric sea level gradient, which significantly affects the water transport during the period of a rapid temperature rise of in the Norwegian Current (1995–2005).
Atmospheric Planetary Waves at Ionospheric Heights Measured at the Moscow Observatory (IZMIRAN)
Authors: Riabova S. A. , Shalimov S. L.
Published: April 2024

The variations of the ionospheric current in the lower ionosphere and the plasma density of the upper ionosphere have been studied based on the monitoring of the horizontal component of the geomagnetic field induction and high-frequency sounding of the critical frequency of the ionosphere F-layer at the Moscow Observatory. It is shown that in the spectra of time variations of the geomagnetic field and the critical frequency of the F2 layer in the range of planetary waves in winter, there are both harmonics associated with solar activity and harmonics corresponding to quasi-5, 10, and 16-day planetary waves. Involvement of geomagnetic field registration data for a twenty-year time interval (from 2001 to 2020) made it possible to identify more subtle effects, namely, the harmonics associated with the modulation effect of longer-period variations and tidal effects were identified.
DYNAMIC PROPERTIES OF MIXED FULLERENOL/BOVINE SERUM ALBUMIN FILMS ON WATER SURFACE
Authors: ISAKOV N. A. , NOSKOV B. A.
Published: April 2024

The properties of a mixed fullerenol (C60(OH)20)/bovine serum albumin film on a water surface depend on the method of film preparation. When the components are adsorbed from a solution of their mixture, the properties of such a film are mainly determined by the protein, which is more surface-active. At the same time, the compression isotherms of such films noticeably deviate from the results obtained for the films of the pure protein. When one of the components is adsorbed on a surface that contains a film of the other component, a synergistic effect is sometimes observed. In this case, the surface pressure and the dynamic surface elasticity modulus are markedly higher than their values for solutions of individual components due to strong interactions between the components and the formation of fullerenol/protein complexes in the surface layer.
ANALYSIS OF ENTROPY PRODUCTION OF IMMISCIBLE MICROPOLAR AND NEWTONIAN FLUIDS FLOW THROUGH A CHANNEL: EFFECT OF THERMAL RADIATION AND MAGNETIC FIELD
Authors: YADAV PRAMOD KUMAR , Kumar Ankit , FILIPPOV A. N.
Published: April 2024

This paper aims to analyze the thermal characteristics, entropy production, flow velocity and Bejan number profile for immiscible nature of micropolar and Newtonian viscous fluid within a channel. Here, the authors emphasize the influence of thermal radiation and oriented magnetic field on the thermal profile and entropy generation of two different types of non-miscible and incompressible micropolar and Newtonian fluids in a channel. The viscous dissipation and thermal radiation effect are also considered in the thermal energy equation. In this work, the entropy production is analyzed within a channel due to oriented magnetic field and thermal radiation. A constant pressure gradient acts on the entry zone of flow domain and static walls of the channel are isothermal. In this problem, we tried to simulate thermal radiation in energy equation by adopting the Rosseland’s diffusion approximation. According to geometrical configuration of the problem, the conditions of no-slip at the walls of the channel and continuity of thermal exchange, microrotation, shear stress, flow velocity and heat flux at the interface of immiscible fluids are used. The governing equations for the flow of immiscible fluids are solved by reliable technique and exact solution for thermal characteristics and flow field are evaluated. The mathematical results of thermal profile and flow characteristics are used to obtain the Bejan number profile as well as the entropy production number profile. The influence of various thermo-physical governing parameters such as radiation parameter, Reynolds number, inclination angle parameter, viscous dissipation parameter, micropolarity parameter and Hartmann number, which describe the physical significance of the present model, on the flow and thermal characteristics of the model are discussed graphically. The newly obtained results of this study are verified with previous published results.
INERTIAL DEPOSITION OF SUBMICRON AEROSOLS IN MODEL FIBROUS FILTERS COMPOSED OF ULTRAFINE FIBERS
Authors: KIRSH V. A.
Published: April 2024

The influence of the inertia of submicron particles on their deposition from a Stokes flow in model fine-fiber filters is considered at low Reynolds numbers. The fiber collection efficiencies are calculated by the limiting trajectory method for a cell model of the filter and for a row of parallel fibers oriented perpendicularly to the direction of the gas flow for the ranges of interception parameter R = 0.01–1, Stokes number Stk = 0–20, and Knudsen number Kn = 0–1. The simulation results are consistent with the experimental data.
WATER-SOLUBLE INTERPOLYELECTROLYTE COMPLEX BASED ON POLY(DIALLYLDIMETHYLAMMONIUM CHLORIDE) AND SODIUM POLYACRYLATE AS A COMPONENT FOR CREATING STABLE BIOCIDAL COATINGS
Authors: PIGAREVA V. A. , BOL’SHAKOVA A. V. , MARINA V. I. , SYBACHIN A. V.
Published: April 2024

Polycation-based coatings represent a promising class of protective antimicrobial coatings. Water-soluble complexes of poly(diallyldimethylammonium chloride) (PDADMAC) with sodium polyacrylate (PANa) have been studied by turbidimetry. It has been shown that the addition of the polyanion (12 mol %) to the polycation leads to the formation of an interpolyelectrolyte complex (IPEC) stable with respect to phase separation in water-salt media with salt concentrations as high as 0.1–0.2 M. In contrast to the traditional method of obtaining coatings from IPEC by layer-by-layer deposition, we have studied the preparation of the coatings directly from a solution of water-soluble IPEC on a hydrophilic glass surface and a surface of more hydrophobic polycarbonate. It has been found that the formation of IPEC makes it possible to increase the resistance of the coating to wash-off with water compared to the individual PDADMAC coating on both types of substrates.
IN SITU ENCAPSULATION OF NICKEL NANOPARTICLES IN POLYSACCHARIDE SHELLS DURING THEIR FABRICATION BY ELECTRICAL EXPLOSION OF WIRE
Authors: SAFRONOV A. P. , BEKETOV I. V. , BAGAZEEV A. V. , MEDVEDEV A. I. , MURZAKAEV A. M. , TERZIYAN T. V. , ZUBAREV A. YU.
Published: April 2024

Nickel nanoparticles are obtained by electrical explosion of wire under the action of a high-voltage discharge followed by condensation in an inert gas medium. When butane is added to the gas medium, a carbon shell is deposited onto the condensing nickel particles. Immediately after the synthesis, liquid-phase modification of nanoparticles is carried out with aqueous solutions of polysaccharides agarose and gellan. As a result, a polymer shell is formed on particles of Ni and nickel particles coated with a carbon shell (Ni@C). The dispersity, crystalline structure, and magnetic properties of Ni and Ni@C nanoparticles are characterized by transmission microscopy, X-ray diffraction analysis, and vibration magnetometry. The total carboncontent on the surface of the nanoparticles is determined by thermal analysis with simultaneous mass spectrometry. It is shown that, under the studied conditions, polysaccharides are deposited onto the nanoparticles in amounts up to 2 wt % to form a shell with a thickness of about 4 nm. When agarose is used as a modifier, the content of the polysaccharide increases with the concentration of the modifying solution. When gellan is used as a modifier, a more complex concentration dependence is observed: an initial increase is followed by a decrease in the amount of deposited polysaccharide. The results are discussed from the viewpoint of the influence of the molecular weight of a polymer on the adsorption process.
MOLECULAR SIMULATION OF WATER STRUCTURE IN NARROW SLITLIKE PORES
Authors: FOMIN YU. D. , TSIOK E. N. , BOBKOV S. A. , RYZHOV V. N.
Published: April 2024

The structure of water in narrow slitlike pores has been studied by the methods of molecular dynamics simulation. Pores with interwall distances of 6.2–15.5 Å have been considered. Water structures resulting from spontaneous crystallization upon cooling to T = 300 K have been clarified on the basis of twoand three-dimensional order parameters. It has been shown that the observed structures can be described as sections of FCC or HCP crystals.
ON THE EFFECT OF VISCOSITY RELAXATION ON ELECTROMAGNETIC RADIATION INTENSITY OF AN OSCILLATING CHARGED DROPLET
Authors: GRIGOR’EV A. I. , KOLBNEVA N. YU. , SNIRYAEVA S. O.
Published: April 2024

Theoretical asymptotic calculations linear with respect to small dimensionless amplitude of oscillations have been employed to study the influence of the viscoelastic properties of a charged droplet of an electrically conducting viscous liquid on the intensity of its electromagnetic radiation. It has been shown that allowance for the effect of viscosity relaxation leads to a decrease in the damping decrement value, which is determined by energy losses for electromagnetic wave emission, and the intensity of high-frequency electromagnetic radiation; a substantial reduction in the viscous damping decrement of small cloud droplets; and an essential dependence of the viscous damping decrement on the characteristic relaxation time. It has been found that the viscosity relaxation of a liquid has no significant effect on damped capillary oscillations and electromagnetic radiation of rain droplets. Viscoelasticity and viscosity of the liquid do not influence the conditions critical for the realization of the electrostatic instability of a droplet with respect to its own charge.
Effect of Aging and Modification on the Interfacial Interaction in Asphalt Mastics
Authors: Dudareva T. V. , Krasotkina I. A. , Gordeeva I. V. , Nikolsky V. G. , Gorelisheva L. A. , Garmanov V. N.
Published: April 2024

In the temperature range –10–30°С the influence of thermo-oxidative aging, frequency and deformation on the interfacial interaction according to the parameters K–B–G* and К–В–δ in asphalt mastics and modified mastics based on bitumen grade BND 60/90 has been investigated. The filler was introduced into bitumen in the ratio of 1/1 by weight. Active powder of discretely devulcanized rubber (APDDR) as a modifier was introduced in the ratio bitumen/APDDR = 87.5/12.5 by weight. It is shown that the modification of APDDR provides a greater thickness of adsorbed layer on the surface of filler particles under various conditions of external influences compared to mastic, and this thickness depends on the sequence of introduction of filler and APDDR.
Etoposide-Loaded Colloidal Delivery Systems Based on Biodegradable Polymeric Carriers
Authors: Merkulova M. A. , Osipova N. S. , Kalistratova A. V. , Ermolenko Yu. V. , Gel’perina S. E.
Published: April 2024

The review is focused on the etoposide delivery systems based on colloidal carriers, i.e., nanoparticles and micelles made of synthetic and natural polymers. Etoposide, a topoisomerase II inhibitor, occupies an important place in the chemotherapy of a number of tumors; however, its use is often limited due to severe side effects. The application of colloidal delivery systems makes it possible to change the pharmacokinetic parameters of etoposide and increase its accumulation in tumors leading to an increase in the antitumor effect. Of particular interest are stimuli-sensitive systems that respond to specific conditions in the tumor microenvironment, which can significantly increase the selectivity of the drug.
Effect of Biological Contamination of Copper Surfaces with Extreme Wettability on Their Antibacterial Properties
Authors: Omran F. S. , Kaminsky V. V. , Emelyanenko K. A. , Emelyanenko A. M. , Boinovich L. B.
Published: April 2024

Bacterial health care-associated infections (HCAI) are one of the acute problems of modern healthcare. One of the promising directions for solving this problem is the development of materials that either have a bactericidal effect against HCAI pathogens or prevent the transmission of bacteria deposited on their surface by patients and staff contacts with such surfaces. In this work, the antibacterial effectiveness of copper contact surfaces with different wettability was investigated. Particular attention was paid to studying the effect on this efficacy of surface contamination by both human contact sweat and bacterial life-supporting substances, using a peptone solution as an example. Due to the high cost of copper, the possibility of replacing bulk copper material with less expensive sprayed copper-coated materials was also investigated. The test results showed that the bactericidal efficacy against Staphylococcus aureus strain of both control copper and superhydrophilic copper samples, as well as of sputtered copper films, is close to 100% and almost unchanged after contamination with peptone solution or sweat excretions. Superhydrophobic copper surfaces have less bactericidal efficacy, but due to the non-wettability effect and low cell adhesion to such surfaces, they remain uncontaminated longer and thus also promote reducing the transmission of infections through the touch surfaces made of them.
Lipid Nanoparticles for Lutein Encapsulation and Delivery
Authors: Shirokikh A. D. , Guruleva Yu. A. , Marinets E. A. , Koroleva M. Yu.
Published: April 2024

Recently, lipid nanoparticles have been intensively studied as carriers of lipophilic drugs. In this work, we have studied the stability of nanoemulsions with paraffin oil, solid lipid nanoparticles with stearic acid, and nanostructured lipid particles with paraffin oil and stearic acid in a mass ratio of 1 : 1. The obtained results have shown that all studied lipid systems stabilized with nonionic surfactants Tween 60 and Span 60 were stable to aggregation and subsequent sedimentation for more than 30 days. The incorporation of lutein into the lipid particles has almost no effect on their stability, while the size of solid lipid nanoparticles and nanostructured lipid nanoparticles decreases from 28–30 to 15–17 nm. The bioavailability of lutein loaded in lipid nanoparticles is evaluated from their effect on the restoration of blood flow velocity by simulating hemic hypoxia. Almost immediately after the application of lipid nanoparticles, the blood flow velocity ceases to decrease, and a tendency to its restoration is observed in 5–10 min. This shows that lipid nanoparticles with paraffin oil and stearic acid are promising candidates for the delivery of lipophilic drugs.
The Role of Dispersed Particles in the Physicochemical Behavior of Nanofluids
Authors: Emelyanenko A. M. , Boinovich L. B.
Published: April 2024

Nanodispersions can be used to solve various practical problems, such as increasing the efficiency of heating systems, cooling of electrical equipment, intensifying oil recovery, etc., because dispersing nanoparticles in liquid media provides an inexpensive and convenient way to significantly improve various functional properties of a base fluid. Although the influence of dispersed particles on surface phenomena in systems comprising nanofluids has been studied for more than 30 years, due to a number of factors, the problem of appropriate and self-consistent description of the behavior of nanofluids will apparently remain to be the focus of scientific attention in the coming decades. This paper presents a brief review of recently published results that are of general importance for understanding the behavior of the surface tension of nanofluids, as well as the processes accompanying wetting with nanofluids and their spreading over various surfaces.
RECYCLING OF NANOPARTICLES STABILIZED EMULSION NANOFLUID MEMBRANE FOR THE REMOVAL OF DICLOFENAC: STABILITY AND PERFORMANCE ASSESSMENT
Authors: SHARMA ANSHUL , KOHLI HIMANSHU P. , CHAKRABORTY MOUSUMI
Published: April 2024

Emulsion instability is the main concern of the emulsion liquid membrane process for industrial use. The present investigation focuses on the removal of Diclofenac (DCF) from an aqueous solution by multiwall carbon nanotubes, Fe2O3, and SiO2 nanoparticles stabilized emulsion nanofluid membrane (ENM). The current study also emphasizes the recycling of nanoparticles and assesses the stability and performance of the ENM system. The optimization of parameters like treat ratio, emulsification time, and agitation speed was carried out by the application of Box−Behnken design and interaction plots were used for understanding the interdependence between the parameters and their combined effect on the % extraction of DCF. The optimum values for maximum removal of DCF were observed in the range: agitation speed: 400–500 rpm, emulsification time: 2.5–5 min, and treat ratio: 10–14. The ENMs were characterized by ATR-FTIR, DLS, photomicrographs, and Turbiscan. Emulsion recycling was also carried out for the reutilization of nanoparticles and the membrane phase. Turbiscan analysis of recycled ENMs was performed to examine the stability of ENMs after each cycle.
Simulation of a Multifractal Turbulent Electromagnetic Field in Cosmic Plasma
Authors: Levashov N. N. , Popov V. Yu. , Malova H. V. , Zelenyi L. M.
Published: April 2024

A two-dimensional model of a multifractal turbulent electromagnetic field is proposed that allows flexibly varying the width of the multifractal spectrum and the level of intermittency. The electromagnetic field is modeled using a superposition of wavelets that are distributed uniformly throughout the computational domain. By means of a special distribution of amplitudes, we ensure that the resulting field is multifractal and intermittent. This model was used to study the effect of multifractality and intermittency on the acceleration of charged particles in a turbulent field in the Earth’s magnetotail. It was shown that, in the case of a multifractal field, individual particles are able to achieve higher energy values in comparison with monofractal turbulence.
Research for Optimal Programs for Controlling the Relative Motion of a Spacecraft with Limited Thrust
Authors: Ishkov S. A. , Filippov G. A.
Published: April 2024

The problem of optimal control of the relative motion of a spacecraft with a finite thrust engine in arbitrary circumcircular orbits using the Pontryagin’s maximum principle is considered. Motion is studied in an orbital cylindrical coordinate system, using variables written in the form of secular and periodic components of relative motion in the orbital plane. The main attention is paid to the analysis of the optimal control structure with a free and transversal orientation of the thrust vector in the presence of passive areas on the trajectory. As a criterion for choosing the optimal control, the motor operating time of the corrective motors was considered. Characteristic control structures for various areas of initial driving conditions have been determined, and estimates of the marginal costs of motor time have been obtained.
Study of the Green Coronal Line with Altitude from Out-of-Eclipse Observations during Solar Cycle 24
Authors: Guseva S. A. , Shramko A. D.
Published: April 2024

The results of studies of the coronal emission line λ = 5303 Å (Fe XIV) for the period of solar cycle 24 are presented. The spectral data were obtained with an out-of-eclipse Lyot coronagraph at the Mountain Astronomical Station of the Pulkovo Observatory, Russian Academy of Sciences (near Kislovodsk). As a result of processing of out-of-eclipse observations, a database of three types of daily coronal maps of green line intensity I5303 was created with a height distribution h from 1R☉ to 1.38R☉ (R☉ is the radius of the Sun). Irregularities along the λ = 5303 Å line were found and identified, which were associated with the configuration of magnetic fields in the solar corona above active regions. The length of the green line from the position angle of the Sun was calculated. We have shown that the time distribution of the line length in the polar regions has two maxima, which coincide with the times of the reversal of the polar magnetic field on the Sun. The maximum values of the average length of the coronal line along the entire limb occur in 2012–2014. For different phases (the rise, the period of maximum, the decline, and the minimum solar activity) of this solar cycle and for different regions of solar activity, dependences of the height variations of the I5303 values were plotted and studied. The regression equations for these fitting curves are presented. The variation in I5303 with height for the polar regions is most likely determined by a logarithmic function, and the approximating trend curves for the remaining latitudinal zones are determined by a third-order power function.
The Optimal Control by the Thrust Vector of Air-Breathing Electric Propulsion to Maximize the Apogee Altitude of Orbit with an Ultra-Low Perigee
Authors: Filatyev A. S. , Yanova O. V.
Published: April 2024

The problem of changing the apogee altitude of orbits with ultralow perigee (altitude 120–250 km) is considered. To compensate for the aerodynamic drag of the spacecraft, an air-breathing electric propulsion (ABEP) is used, the fuel for which is the gases of the outboard atmosphere. The decrease in the efficiency of an ABEP with an increase in the angle of attack and the possibility of ABEP operation only at a sufficient gas concentration in the ionization chamber are taken into account. The problem is solved on the basis of the Pontryagin maximum principle under the assumption that the aerodynamic drag and thrust are small compared to the gravitational forces. The results of studies of optimal programs for controlling the thrust vector of an ABEP depending on the parameters of the orbit, the layout of the spacecraft, the engine, and the power of the energy source are presented.
Space–Time Structures in the Auroral Oval: Approaches to Modeling
Authors: Kozelov B. V.
Published: April 2024

The interaction of the magnetospheric–ionospheric (MI) system surrounding the Earth with the environment (solar wind) occurs in the form of a series of transient processes at different scales. The largest of them, magnetic storms, are obviously triggered by disturbances in the solar wind (direct driving). The role of the internal dynamics of the MI system, which is caused to a large extent by the nonlinearity and temporal delays of the loading–unloading processes of energy and particle from the solar wind into the magnetosphere, becomes more significant at smaller scales (substorms, pseudobreakups, injections, and activations). A typical dynamic state of the MI system is characterized as self-organized criticality or turbulence, which are characterized by statistical scale invariance (scaling) in the fluctuation distributions of many characteristics. The dynamics of the MI system is projected into the region of the auroral oval, the very existence of which is due to this dynamics. The space–time structure of auroral disturbances largely reflects the structure of processes in the MI plasma. The description of this structure is important both for studying the fundamental study of plasma processes and for many topical applied problems related to the propagation of radio waves in the ionosphere and vital activity at high latitudes. The paper discusses approaches and developments for constructing a model of the space–time structure of the auroral oval, based on fractal and multifractal characteristics.
Fe Ion Composition in Solar-Wind Streams in the Solar Corona and Heliosphere
Authors: Goryaev F. F. , Slemzin V. A. , Rodkin D. G. , Shugai Yu. S.
Published: April 2024

Analysis of the distributions of Fe ions over the stages of ionization in solar-wind (SW) plasma provides valuable information on the formation of SW streams and plasma heating processes, as well as for identifying SW sources on the Sun. When passing SW plasma through the corona, its ion composition evolves and finally “freezes” at distances of the order of several solar radii from the solar surface, remaining further practically unchanged in the heliosphere. This makes it possible to obtain information about the physical conditions in its source and the solar corona from the SW charge state. Average charge QFe, which is usually used to characterize the distributions of Fe ions, does not take into account all the features of the evolution of the ion composition, which does not allow one to extract more detailed information about the state of SW plasma. In this study, to describe the charge state of Fe ions, three parameters q4, q8, and q12 are introduced, which characterize the relative fractions of ions with charges Z = 0–7, 8–11, and 12–20, respectively, and conditionally correspond to “cold,” “medium,” and “hot” SW plasma components. According to the measurements of the Fe ion composition in 2010 on the STEREO-A spacecraft, the characteristic values of these parameters for different types of SW streams are given. The problem of modeling ion distributions in SW plasma based on diagnostic data on the parameters of coronal sources is considered. Using the example of the event associated with coronal-mass ejection on August 18, 2010, it is shown that the parameters of the charge state of Fe ions calculated from the model distributions are in good agreement within errors with the measurement data.
Automatic Detection of Bow Shock and Magnetopause Positions at Mercury’s Magnetosphere Using MESSENGER Magnetometer Data
Authors: Nevskii D. V. , Lavrukhin A. S. , Alexeev I. I.
Published: April 2024

The MESSENGER spacecraft completed more than 4000 orbits around Mercury during 4 years of operation on orbit around the planet. Using the onboard magnetometer data, we determine the bow shock and magnetopause crossings in Mercury’s magnetosphere by automatic methods and compare the accuracy of these methods with the results of manual data processing. The developed algorithm makes it possible to significantly increase the magnetometer data processing rate and can be used in the future when analyzing data from the BepiColombo spacecraft, which is going to enter Mercury’s orbit in 2025.
OPTICAL ISOLATORS ON SURFACE ELECTROMAGNETIC WAVES IN PT-SYMMETRIC GYROTROPIC STRUCTURES. I: SPECIAL CASES
Authors: Furs A. N. , Novitsky A. V.
Published: April 2024

It is shown that a twinned PT-symmetric gyrotropic structure, composed of semi-infinite media with oppositely directed gyration vectors, lying in the interface plane, exhibits valve properties for surface electromagnetic waves. More specifically, a surface wave can be excited in one direction lying in the interface plane, which is perpendicular to the gyration vectors, and cannot be excited in the opposite direction. This surface electromagnetic wave is linearly polarized, and its characteristic penetration depth is inversely proportional to the small gyration parameter.
GROWTH OF KR3F10 (R = Tb–Er) COMPOUNDS BY THE VERTICAL DIRECTIONAL CRYSTALLIZATION METHOD. III: MELTING CHARACTER AND NONSTOICHIOMETRY OF CUBIC KHo3F10AND KEr3F10 SINGLE CRYSTALS
Authors: Karimov D. N. , Buchinskaya I. I. , Grebenev V. V.
Published: April 2024

KR3F10 (R = Ho, Er; sp. gr. ) crystals have been grown by the vertical directional crystallization. The incongruent melting of these compounds is experimentally established, and the temperatures of the corresponding thermal effects are determined. Narrow regions of homogeneity are found for the studied crystals; these regions are also characteristic of the entire series of KR3F10 crystals under study. The cubic lattice parameter monotonically decreases along the crystal length and varies in the range of 11.5782(2)–11.5654(5) Å for KHo3F10 and 11.5225(1)–11.5102(4) Å for KEr3F10. The conditions for growing KR3F10 crystals of optical quality from melt are optimized.
POSSIBILITIES OF MODERN SCANNING TRANSMISSION ELECTRON MICROSCOPY FOR STUDYING BORON CARBIDES
Authors: Pavlov I. S. , Bondarenko V. I. , Vasiliev A. L.
Published: April 2024

A promising method of scanning transmission electron microscopy is the use of integrated differential phase contrast. Its advantages include high sensitivity to light elements, almost linear relation between the generated image contrast and atomic numbers of Z atoms contained in a sample, noise suppression, and much more. Using the modeling and mathematical processing, prospects of this technique for studying the crystal structure of materials consisting of light atoms have been analyzed by the example of boron carbide polytypes. It is shown that the sensitivity of the technique makes it possible to distinguish columns of boron atoms from columns consisting of carbon. Recommendations on using this technique for analyzing the structures consisting of light elements are formulated.
GALLIUM NANOPARTICLES OBTAINED ON SILICON SUBSTRATES BY THERMAL EVAPORATION METHOD
Authors: Kozhemyakin G. N. , Belov Yu. S. , Trufanova M. K. , Artemov V. V. , Volchkov I. S.
Published: April 2024

Gallium nanostructures have been obtained on silicon substrates by thermal evaporation in an argon atmosphere. The sizes, density, and shape of Ga particles have been determined by computer processing of electron SEM-images. The condensation of Ga on Si substrates for 10, 15, and 20 s ensured the formation of particles of several types: spherical, triangular, square, and in the form of rods and polyhedrons. The increase in the Ga condensation time to 20 s led to the increase in the density of spherical nanoparticles by 41%.
FILLING OF CHANNELS OF THE ZEOLITE FRAMEWORK IN TRIGONAL POLAR NONABORATE Ва3Na0.9(OH)1.9[B9O16][B(OH)3]
Authors: Topnikova A. P. , Belokoneva E. L. , Dimitrova O. V. , Volkov A. S. , Zorina L. V.
Published: April 2024

Crystals of the new trigonal borate Ва3Na0.9(OH)1.9[B9O16][B(OH)3] (sp. gr. P31c, a =10.23684(15) Å, c = 8.72926(13) Å) were prepared by the mild hydrothermal synthesis. The filling of the channels in the framework of the polar nonaborate was found to differ from that determined previously. It is consistent with the main features of this structure type with the preservation of sassoline molecules in the channels. The structure contains an additional ОН group, which is involved in the coordination of Ва.
Effect of Microgravity on the Crystallization of Cardiotoxin from the Venom of Spectacled Cobra Naja naja
Authors: Dubova K. M. , Dubovskii P. V. , Utkin Yu. N. , Samygina V. R.
Published: April 2024

Cardiotoxins, which belong to the family of three-finger toxins, are the main components of cobra venom. They exhibit various types of biological activity, including antimicrobial and cytotoxic against cancer cells. Data on the minimal structural differences between individual toxins are necessary for understanding the molecular mechanisms of their action. This information can be obtained by high-resolution X-ray diffraction analysis. The influence of microgravity on the crystal packing and diffraction quality of crystals of cardiotoxin from cobra Naja naja has been investigated. Cardiotoxin crystals, which were grown on the International Space Station, provided maximally high resolution for the structure of this toxin. Protein crystallized extremely in the hexagonal space group, whereas more than half of crystals grown under laboratory conditions belonged to the orthorhombic system.
State of Cyanobacteria Arthrospira platensis and of Associated Microflora during Long-Term Storage in the State of Anhydrobiosis
Authors: Kharchuk I. A. , Rylkova O. A. , Beregovaya N. M.
Published: April 2024

Abstract—The biochemical composition of Arthrospira (Spirulina) platensis (Nordstedt) Gomont after long-term storage in the state of anhydrobiosis (4 years, 17 years) was determined by the standard methods. It was shown that protein content (55.3–61.2%) and total carbohydrates content (13.0–15.6%) in cyanobacterial cells were in agreement with the data known from the literature and with our results obtained at the onset of storage. The biomass had low content of free nucleotides (1.8–2.6%), lipids (1.3–11.0%), and especially pigments (0.5–1.3, 0.03–0.12, 1.4–2.0, 0.03–0.05% for chlorophyll a, carotenoids, C-phycocyanin, and allophycocyanin, respectively). The content of nucleic acids content was 3.1–24.0 and 0.11–0.16% for RNA and DNA, respectively. Microscopic examination of A. platensis (17 years of storage) showed high numbers of irreversibly damaged and dead cells (34.2 and 65.8%, respectively). To determine the quantitative and morphological parameters of associated microflora, a complex physicochemical treatment (methanol, ultrasound, and centrifugation) of the reactivated cyanobacterial suspension proved the most efficient. Three main groups were distinguished in the morphological structure of the microbiome (rod-shaped, rounded, and convoluted forms). The community was dominated by rod-shaped forms: large and small rods accounted for 60.5 and 14.4%, respectively. Mycelial forms (thin filaments), cocci, and convoluted forms were less common. On average, the volume of a bacterial cell was 0.27 ± 0.04 µm3. The contribution of bacteria to the biomass of A. platensis varied from 3.3 to 11.3% (8.3 ± 4.4% on average) of the dry weight of A. platensis. It has been suggested that the biochemical parameters and viability of cyanobacteria were affected by the accompanying microflora.
The Effect of Atranes on the Growth of Rhodococcus qingshengii VKM Ac-2784D in the Presence of Various Carbon Sources and on Its Ability to Degrade Naphthalene
Authors: Belovezhets L. A. , Markova Ю. A. , Levchuk A. A. , Oborina E. N. , Adamovich S. N.
Published: April 2024

Abstract—Rhodococcus qingshengii VKM Ac-2784D isolated from the rhizosphere of Elytrigia repens, is a promising oil degrader. To increase its biotechnological potential, the effect of atranes (potential growth stimulants) on its growth and naphthalene degradation was studied. The effect of the studied atranes on R. qingshengii VKM Ac-2784D was shown to depend on the nature of the carbon source: addition of atranes had practically no effect on the growth rate of bacteria in the rich BTN medium; in the media 8E and 8E with glucose, it baused short-term activation of growth, characterized by a shorter lag phase. In the presence of naphthalene, atranes had a predominantly negative effect on the growth of R. qingshengii VKM Ac-2784D. The studied atranes had a negative effect on the rate of naphthalene decomposition by R. qingshengii VKM Ac-2784D, and also decreased the cell wall hydrophobicity and the synthesis of extracellular biosurfactants. It may therefore be assumed that the studied compounds will have a negative effect on the rate of naphthalene decomposition by this microorganism.
Comparative Assessment of Stress Responses of the Microalgae Prorocentrum cordatum (Ostenfeld) Dodge and Dunaliella salina (Teod.) to the Presence of Copper Nanoparticles
Authors: Solomonova E. S. , Shoman N. Yu. , Akimov A. I. , Rylkova O. A.
Published: April 2024

Abstract—Comparative assessment of stress responses of two microalgal species differing in their cell structure and habitats, Prorocentrum cordatum and Dunaliella salina, to the presence of copper oxide nanoparticles (NP) in the medium was carried out. The nanoparticles were found to have a similar effect on both species. Their toxic effect resulted in progressing production of reactive oxygen species in the algal cells, while their specific growth rates decreased, probably due to Cu2+ release from the oxide or to penetration of some nanoparticles into the cells. NP mechanical impact resulted in their aggregation at the cell surface and deformation of the cell envelopes. The presence in the toxicant in the medium caused a reliable increase in cell volume, plasmalemma perforation, and predominance of deformed cells of irregular shape in the cultures. Two species exhibited different resistance to CuO NP. The sublethal and lethal concentrations for P. cordatum were 400 and 520 µg/L, respectively, compared to 3000 and 3750 µg/L for D. salina. The possible causes for resistance of D. salina to CuO NP are discussed. D. salina is able to produce ligands (phytochelatins and metallothionenis) in high concentrations, which may be released into the medium and bind the Cu2+ ions. Moreover, the habitats of D. salina are extreme, which may promote its stress tolerance, probably a genetically determined feature and a part of their overall resistance to other contaminants. High resistance of D. salina to CuO NP may also be due to its ability to secrete extracellular polymers under stress conditions; they may form a protective layer preventing the interaction between the microalgae and NP. Application of P. cordatum for biomonitoring of NP-contaminated seawater environments is proposed. D. salina may be promising for water bioremediation.
Quorum Sensing in Chromobacterium subtsugae (Previously – C. violaceum) Is Inhibited by Gamma-Lactones, the Minor Components of Eucalyptus Leaf Extract
Authors: Inchagova K. S. , Duskaev G. K. , Deryabin D. G.
Published: April 2024

Abstract—The goal of the study was to investigate the mechanism of quorum sensing (QS) inhibition in the model bacterium Chromobacterium subtsugae 026 (previously – C. violaceum 026) by Eucalyptus viminalis Labill leaf extract, and to identify the plant-derived components that provide this biological activity. The raw extract showed pronounced anti-QS activity within a broad concentrations range which were an order of magnitude lower than required for bacterial growth suppression (the MIC50/EC50 ratio of 43.6). Chemical analysis of the extract revealed six small plant-derived molecules: pyrogallol, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-1, p-cymene, 4-((1E)-3-hydroxy-1-propenyl)-2-methoxyphenol, gallic and palmitic acids, whose inhibitory effect on QS in Chromobacterium spp. has previously been shown by in vitro experiments or predicted by in silico models. In addition, minor components γ-caprolactone and γ-octanolactone, structurally similar to acylated homoserine lactones, QS autoinducers in Chromobacterium spp., were found in the extract. Chemically synthesized analogs of these molecules showed anti-QS activity in the C. subtsugae 026 bioassay (ЕС50 = 354.2 and 145.6 µg/mL, respectively). Enrichment of the E. viminalis leaf extract with γ-caprolactone or γ-octanolactone significantly increased the anti-QS activity of these compositions, which was determined by isobolographic analysis as additive or superadditive effects.
A New Methanogenic, Hydrogenotrophic Archaeon from Spitsbergen Permafrost
Authors: Trubitsyn V. E. , Suzina N. E. , Rivkina E. M. , Shcherbakova V. A.
Published: April 2024

Abstract—A new strain of methanogenic archaea, designated VTT, was isolated from a sample of Spitsbergen permafrost. The cells were nonmotile curved rods, 2.7–5.3 × 0.3 µm. The optimal conditions for growth were 20°C, pH 6.6, and NaCl concentrations 0.03–0.05 M. The H2/CO2 gas mixture was the only substrate used. In the presence of H2/CO2, growth was stimulated by addition of yeast extract or rumen fluid. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strain VTT belonged to the genus Methanobacterium and was most closely related to M. lacus 17A1T (97.02% similarity). Comparison of the sequenced and assembled genome of strain VTT with the genomes of other members of this genus confirmed these results and revealed species-level differences. Our results indicate that this methanogenic isolate belongs to a new species of methanogenic archaea, for which the name Methanobacterium spitsbergensе sp. nov. was proposed, with the type strain VTT (=VKM B-3566T = JCM 39284T).
Pectinolytic Yeast Saccharomyces paradoxus as a New Gene Pool for Winemaking
Authors: Borovkova A. N. , Shalamitskiy M. Yu. , Naumova E. S.
Published: April 2024

Abstract—A large-scale screening of pectinolytic activity in the yeast Saccharomyces paradoxus isolated from various natural sources in Europe, Asia, North America, and the Hawaiian Islands was carried out. Of the 98 studied strains, pectinolytic activity was absent only in five Hawaiian and two European strains. Most strains were able to secrete active endo-polygalacturonase. North American strains UCDFST 52-225, UCDFST 61-359, UCDFST 61-220, 95-3, and UCDFST 62-186 had very high pectinolytic activity, comparable to or even higher than that of the experimentally obtained tetraploid strain S. cerevisiae VKPM Y-718. Comparative analysis of the nucleotide and amino acid sequences of pectinase genes showed that the North American and Far Eastern populations of S. paradoxus were more genetically diverse than the European and Hawaiian ones. Phylogenetic analysis confirmed the species specificity of the PGU genes of Saccharomyces yeasts. Of the eight Saccharomyces species, high pectinolytic activity is characteristic of S. bayanus and S. paradoxus. Five North American strains with the highest pectinolytic activity are of interest for further molecular genetic studies and breeding work with wine yeasts. The ecological role of endo-polygalacturonase is discussed.
Biological Activity and Composition of Metabolites of Potential Agricultural Application from Streptomyces carpaticus K-11 RCAM04697 (SCPM-O-B-9993)
Authors: Bataeva Yu. V. , Grigoryan L. N. , Bogun A. G. , Kislichkina A. A. , Platonov M. E. , Kurashov E. A. , Krylova J. V. , Fedorenko A. G. , Andreeva M. P.
Published: April 2024

Abstract—Strain K-11 was isolated from the highly saline brown semi-desert soil of the Astrakhan region. Based on analysis of the 16S rRNA gene sequence, this strain was identified as Streptomyces carpaticus K-11 RCAM04697 (SCPM-O-B-9993). Whole genome sequencing of the strain was performed. Phytotoxicity, antiviral, antioxidant, antifungal, and insecticidal activities of the strain were studied. All extracts and suspensions of S. carpaticus strain RCAM04697 had plant-stimulating activity. Antiviral properties was exhibited as suppression of development and propagation of viral pathogens in laboratory conditions: Tomato Mosaic Virus (ToMV) – 26.3%, Cucumber Mosaic Virus (CMV) – 33.8%, Y-Potato Virus (YVK) (Potato Y potyvirus, PVY) – 51.3%, Potato X-Virus (PVX) (Potato X potyvirus, PVX) – 41.3%. The highest antioxidant activity was shown by a suspension of S. carpaticus strain RCAM04697 (88.8%) and its aqueous-alcoholic (20 : 80) extract (76.0%). The strain inhibited growth of the phytopathogenic fungus Fusarium sporotrichioides to varying degrees. The insecticidal activity against Aphis fabae after 6 h of treatment was 100% in the variants with suspension treatment, water-alcohol (80 : 20, 50 : 50), methanol, and hexane extracts. The metabolites of the S. carpaticus RCAM04697 strain included flavonoids, alkaloids, glycosides, organic acids (isocitric, acetic, fumaric, lactic, pyruvic, and malic), alcohols, aldehydes, hydrocarbons, ethers, sulfur-containing compounds, and other groups of low-molecular weight organic compounds.
Biodegradation of Phthalic Acid Esters by the White Rot Fungus Peniophora lycii
Authors: Savinova O. S. , Shabaev A. V. , Fedorova T. V.
Published: April 2024

Abstract—The ability of the white rot fungus Peniophora lycii to degrade such phthalic acid esters (PAEs) as diethyl phthalate (DEP), dibutyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DiBP), and n-butylbenzyl phthalate (BBP) was studied. It was shown that DEHP was most efficiently biodegraded by the fungus (over 98% on day 6 of cultivation). The residual content of DBP and DiBP in the culture liquid of the fungus at the end of cultivation (10 days) was ~17–18%. BBP turned out to be the most difficult-to-degrade compound: its residual content on day 10 of P. lycii cultivation was ~40%. DEP was resistant to fungal biodegradation, and exhibited a toxic effect at 1.5 g/L: the rate of radial growth of the fungus on agar decreased threefold compared to the control, and the amount of fungal biomass during liquid-phase deep cultivation decreased by about 1.5 times. During the cultivation of P. lycii on media with PAEs, an increase in esterase activity by about 2 times and a significant decrease (by 2–4 times) in oxidase activity was shown compared to the control medium without phthalates.
Adaptation of the Acidophilic Fungus Sistotrema brinkmannii to the pH Factor
Authors: Ianutsevich E. A. , Danilova O. A. , Grum-Grzhimailo O. A. , Groza N. V. , Tereshina V. M.
Published: April 2024

Abstract—Investigation of the growth rate of Sistotrema brinkmannii at different values of pH values, temperature, and NaCl concentration showed that this fungus was a mesophile, preferred a salt-free medium, and was an obligate acidophile, since it had a pronounced growth optimum at pH 3.0–4.0 and did not grow at pH 7.0. To reveal the protective mechanisms allowing this fungus to develop under acidic conditions, the composition of its osmolytes and lipids was studied. This is the first report on occurrence of a large amount of trehalose (4.0‒6.6% of dry weight) in the mycelium of the fungus during its growth under optimal conditions, confirming the use of osmolytes by acidophiles for adaptation. At the same time, at the borders of the growth range (pH 2.6 and 6.0), the amount of trehalose in the mycelium of the fungus decreased by 2.5 times, which was in agreement with a narrow growth optimum of the fungus in its natural environments (pH 3.0–4.0). The composition of membrane lipids of the fungus was characterized by a high proportion of sphingolipids (up to 60% of the total), which decreased twofold in the course of growth under optimal conditions. The main membrane lipids, apart from sphingolipids, were phosphatidic acids, phosphatidylethanolamines, and sterols; the proportion of these lipids increased with time. The composition of membrane lipids of the fungus at pH 2.6 did not differ much from the optimal conditions, while in the near-neutral region there was a twofold increase in the proportion of sphingolipids, indicating their adaptive value. The simultaneous decrease in the proportion of sphingolipids and the increase in the level of trehalose in the growth dynamics suggest association of these compounds in the protection of cell membranes.