bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of the Maneuver to Ensure a High Velocity of the Spacecraft Entry into the Atmosphere
Authors: Konstantinov M. S.
Published: April 2024

The transfer scheme that provides a parabolic entry of the spacecraft into the Earth’s atmosphere has been optimized. Such a maneuver can be of interest in experimental testing of the spacecraft reentry from the Moon or after interplanetary missions. It is assumed that the spacecraft is inserted into a low Earth orbit and is equipped with a chemical propulsion system and a limited-thrust engine, which should provide a maneuver to bring the spacecraft into the Earth’s atmosphere. The optimization criterion takes into account the characteristic velocity of the maneuver. The developed method of optimizing the transfer scheme and the spacecraft trajectory itself is based on the maximum principle. Single-revolution and multi-revolution transfer trajectories are analyzed. It is shown that for single-revolution trajectories there is an optimal time and an optimal angular distance of flight. Their values and the minimum characteristic velocity of the maneuver are evaluated. Unlike single-revolution trajectories, the characteristic velocity for multi-revolution trajectories monotonically decreases with increasing transfer duration. The dependence of the characteristic velocity on the transfer duration for single-, two-, three- and four-revolution trajectories is given. The transfer duration ranges in which it is advisable to use each type of trajectory are analyzed.
COHERENCE ASSEMBLY IN STRUCTURES WITH HEAVY METAL CLUSTERS
Authors: Pervukhina N. V. , Borisov S. V. , Magarill S. A.
Published: April 2024

A crystallographic analysis of two structures, monoclinic Nа8[{Re4(PO)4}(CN)12]⋅18H2O⋅CH3OH (I) and orthorhombic [(C6H5)4P]4 [Ta6I12(CN6)] (II), in which clusters of heavy atoms are significantly rarefied in space, so that their mutual arrangement cannot be explained only in terms of chemical interaction, has been performed. In structure I the crystallographic planes with a high atomic density (“skeletal” planes) are located in the regions with dhkl = 10–5.5 Å and dhkl 3 Å. The planes in which atomic groups [Re4(PO)4] (playing the role of unified bulk objects) are concentrated are in fact selected in the first region. In the second region, ordering is implemented at the level of individual atoms. A crystallographic analysis showed that the structure basis is determined by the sites of heavy Re cations. A striking fact is that there are 1152 subcells and only 32 Re atoms per unit cell in this structure; i.e., only the fraction of 1/144 provides the basis of structure stability. In structure II “skeletal” planes are also absent in the range of dhkl from ∼7 to ∼4 Å. The planes in the range of large dhkl characterize cluster ordering, whereas the planes in the range of small dhkl characterize ordering of separate atoms. The geometry and local symmetry of the cluster group (Та6 octahedron) dictates the basis of translational symmetry—unified sublattice of sites, most of which are free of these atoms. The considered structures demonstrate the key role of heavy atoms in the formation of translational symmetry—the fundamental difference of the crystalline state from other condensed states. The newly formed structure retains partially local symmetry of cores (templates) of atomic groups, bound by strong chemical interactions, including the interactions between heavy and light atoms. The process of formation of a crystal structure from randomly oriented and randomly located templates—coherence assembly—is implemented according to the laws of dynamics of elastic media, where masses of atoms rather than their chemical characteristics are important.
AUTOMATED TEM DIFFRACTION MAPPING SOFTWARE PACKAGE
Authors: Karateev I. A. , Ovcharov A. V. , Karateeva K. G. , Presnyakova N. N. , Kamyshinsky R. A.
Published: April 2024

The results of developing a software package for automated orientational mapping based on diffraction data are presented. The experimental module of the software is responsible for the communication with a microscope and acquisition of diffraction maps. The analytical module automatically processes and solves diffraction patterns obtained by transmission electron microscopy. The test data analysis has shown the diffraction mapping results to be consistent with the model data.
Objective Criteria for Estimation of Initial Parameters for the Modeling of Micelle and Liposome Structures from Small-Angle X-ray Scattering Data
Authors: Petoukhov M. V. , Shtykova E. V.
Published: April 2024

The structures of hydrophobic membrane proteins are studied using matrices, which serve as models of cell membranes and are formed by the appropriate amphiphilic molecules, e.g., by surfactant or lipid molecules. To study the structure of a protein incorporated into an artificial membrane, first of all it is necessary to determine the structure of the membrane. The ELLLIP and ELLMIC algorithms were previously developed to address this issue by small-angle X-ray scattering. These algorithms allow the construction of models of ellipsoidal vesicles based on the atomic structure of a lipid or surfactant monomer. However, the results of modeling depend, to a large extent, on the subjective assessment of the initial values of the structural parameters of the matrices and may be wrong due to the ambiguity in the solution of such problems. Here, we present an independent approach to the determination of the initial sizes of model membranes for their subsequent structural modeling, which is based on the analysis of the pair-distance distribution functions derived directly from the small-angle X-ray scattering curve.
ATOMIC FORCE MICROSCOPY AND THE BUILDING PARTICLE IN THE FLUCTUATION THEORY OF CRYSTAL GROWTH
Authors: Rakin V. I.
Published: April 2024

The specific features of application of a low-energy atomic-force microscope (AFM) for studying the dynamic process of face growth in terms of the fluctuation model of crystal growth are discussed. It is shown that the probe interaction with an area of growing crystal surface on the time scale characteristic of a sequence of free energy fluctuations is a limiting factor for constructing an image of growing face surface.Agreement between the phenomenological and quantum (according to the uncertainty relation) descriptions of the effect of limiting magnification for a growing crystal face in an AGM is demonstrated. Specific features of detecting a growth stage on a crystal face using a transmission/scanning high-resolution electron microscope in a gas medium are also discussed. The effect of ultimate magnification when observing crystal growth in an АСМ is a basis for discussing the concept of the transient state of matter in the topochemical reaction of crystal growth and the phenomenon of building particle.
COMPLEXES OF ETHYLENEDIAMINETETRAACETIC ACID WITH AMINES. MOLECULAR STRUCTURES OF BIS(MONOETHANOLAMINIUM) ETHYLENEDIAMINETETRAACETATE AND BIS[TRIS(HYDROXYMETHYL)METHYLAMINIUM] ETHYLENEDIAMINETETRAACETATE TRIHYDRATE
Authors: Semenov V. V. , Zolotareva N. V. , Novikova O. V. , Petrov B. I. , Lazarev N. M. , Fukin G. K. , Cherkasov A. V. , Razov E. N.
Published: April 2024

Tetrabasic ethylenediaminetetraacetic acid H4L binds two molecules of monobasic amines to give the corresponding salts: ethylenediaminetetraacetates of bis(monoethanolaminium) H2L2–⋅2+H3NCH2CH2ОН, tris(hydroxymethyl)methylaminium H2L2–⋅2+H3NС(CH2ОН)3⋅3H2О, diethylaminium H2L2–⋅2+H2N(C2H5)2⋅H2О, tert-butylaminium H2L2–⋅2+H3NС(CH3)3⋅5H2О, and triethanolaminium H2L2–⋅2+HN(CH2CH2ОH)3. Dibasic hexamethylene-1,6-diamine, triethylenediamine, and tetramethylethylenediamine form the following 1 : 1 adducts: H2L2–⋅+NH3(CH2)6NH , H2L2–⋅+NH3CH2CH2(OCH2CH2)2NH , H2L2–⋅ +HN(CH2)3NH+⋅H2О, and H2L2–⋅+H(CH3)2NCH2CH2N(CH3)2H+. The molecular structures of bis(monoethanolaminium) ethylenediaminetetraacetate and bis[tris(hydroxymethyl)methylaminium] ethylenediaminetetraacetate trihydrate were determined
LUMINESCENCE OF TWO-DIMENSIONAL ZnO NANOSTRUCTURES: NANOWALLS, NANOSHEETS, NANOCOMBS
Authors: Tarasov A. P. , Zadorozhnaya L. A. , Nabatov B. V. , Volchkov I. S. , Kanevsky V. M.
Published: April 2024

Preliminary comparative studies of the photoluminescent properties of two-dimensional ZnO nanostructures with morphology of nanowalls, nanosheets, and nanocombs, fabricated by gas-transport synthesis, have been performed. All structures exhibited near-band-edge (NBE) UV emission of the same order of intensity. Unlike nanocombs, whose spectrum contains a comparatively strong green luminescence band, nanowalls and nanosheets are characterized by a large ratio of the UV and visible components. This distinction is presumably due to the difference in the mechanisms of structure formation: nanowalls and nanosheets are formed according to the vapor–liquid–solid mechanism, whereas nanocombs grow according to the vapor–solid mechanism
Preliminary X-ray Study of Crystals Obtained by Co-Crystallization of Hypoxanthine‒Guanine Phosphoribosyltransferase from Escherichia coli and Pyrazine-2-Carboxamide Derivatives
Authors: Abramchik Yu. A. , Zayats E. A. , Timofeev V. I. , Shevtsov M. B. , Kostromina M. A. , Fateev I. V. , Yurovskaya D. O. , Karanov A. A. , Konstantinova I. D. , Kuranova I. P. , Esipov R. S.
Published: April 2024

A highly effective producer strain Escherichia coli C3030/pET23d+-EcHGPRT, allowing production of recombinant hypoxanthine‒guanine phosphoribosyltransferase from E. coli (EcHGPRT) in a soluble form, has been created. A method for isolating and purifying the recombinant protein has been developed. The specific activity against the natural substrate and pyrazine-2-carboxamide derivatives has been determined. Crystals of the EcHGPRT complexes with 3-hydroxypyrazine-2-carboxamide (T-1105) and 6-fluoro-3-hydroxypyrazine-2-carboxamide (T-705), suitable for X-ray diffraction analysis, have been grown by capillary counter diffusion. X-ray diffraction sets with a resolution of up to 2.4 and 2.5 Å have been collected at the ESRF synchrotron (France, station ID23-1) at a temperature of 100 K. The crystals belong to the sp. gr. P3(1)21; the independent part of the cell contains two enzyme molecules.
Decomposition of Small-Angle Scattering Profiles from Two Conformational States of 3-Isopropylmalate Dehydrogenase Using Evolving Factor Analysis
Authors: Konarev P. V. , Volkov V. V.
Published: April 2024

The separation of two conformational states of 3-isopropylmalate dehydrogenase molecules from Thermus thermophilus in solution on a gel chromatographic column, attached to a sample cell of a small-angle X-ray scattering synchrotron beamline, has been simulated. The scattering intensity profiles from the open and closed forms of the enzyme molecules were restored by evolving factor analysis (EFA) using the synthetic data set with added Poisson noise at the relative level of 3–5%. Thus, the efficiency of the EFA algorithm is confirmed in the case of two-component mixtures consisting of particles with the same molecular masses.
THE STUDY OF GROWTH DEFECTS IN CUBIC SINGLE CRYSTALS OF SYNTHETIC DIAMOND USING X-RAY TOPO-TOMOGRAPHY
Authors: Anisimov N. P. , Zolotov D. A. , Buzmakov A. V. , Dyachkova I. G. , Asadchikov V. E.
Published: April 2024

The spatial distribution of linear defects in cuboctahedral single crystals of synthetic diamonds, grown under laboratory conditions by the high-pressure high-temperature (HPHT) method near the diamond–graphite equilibrium line, has been studied. Synthetic diamonds of this type have been studied for the first time by the X-ray topo-tomography using a laboratory X-ray source.
INVESTIGATION OF THE ULTRAFAST MAGNETIC DYNAMICS IN Co/Pt MULTILAYER STRUCTURES AND EXAMPLES OF OTHER STUDIES AT THE EUROPEAN XFEL FACILITY
Authors: Lobanova E. Yu. , Suturin S. M. , Molodtsov S. L. , Romanov A. E.
Published: April 2024

The European X-ray Free-Electron Laser (EuXFEL) Facility is the leading international scientific center for studying the structure and properties of materials using coherent X-rays with high temporal and spatial resolution. The results of the collaboration of the EuXFEL experts and the researchers of the ITMO University in 2015–2022 are briefly described. The unique possibilities of the EuXFEL are demonstrated by an example of studying the ultrafast magnetic dynamics by the researchers of the ITMO University in 2019.
SOLUTION-GROWN TRANS-STILBENE SINGLE CRYSTAL AND ITS SCINTILLATION PROPERTIES
Authors: Lyasnikova M. S. , Kulishov A. A. , Yurasik G. A. , Postnikov V. A. , Karakash A. I. , Voloshin A. E.
Published: April 2024

Trans-stilbene single crystals are of great interest for researchers as scintillators characterized by a high specific light yield. Bulk trans-stilbene single crystals have been grown from an anisole solution. The transmission and photoluminescence spectra have been recorded, and the single-crystal photoluminescence quenching kinetics has been investigated. The scintillation properties of an element (17 × 12 × 5 mm in size) prepared from a grown trans-stilbene crystal, irradiated by γ radiation and X rays, have also been investigated. It is shown that the specific light yield of the obtained crystal is no less than that of a scintillation detector (31.5 × 10 mm) based on a trans-stilbene crystal grown from melt.
Determination of the Shape of a Helix Particle Based on Small-Angle X-ray Scattering Data: Modification of the “Simulated Annealing” Algorithm
Authors: Grigorev V. A. , Konarev P. V. , Volkov V. V.
Published: April 2024

The modified “simulated annealing” algorithm implemented in the DAMMINV software allows one to obtain 10 to 15 different nanoparticle models fitting small-angle X-ray scattering data. This method is based on the mode of intermittent weights of the objective function, which balances between minimization of the penalty coefficients, responsible for the model meaningfulness, and the discrepancy between the experimental and model scattering data. The effect of noise on the scattering curves on the quality of three-dimensional helix shape reconstruction has been investigated, and the results are compared with the data obtained using standard programs. The method has been verified on noise-free model data and data with superimposed Poisson noise by the example of a helix particle with a thickness of turns comparable to the characteristic size of the space between them. A comparative analysis of the reconstructed models and the three-dimensional shapes obtained using standard modes of the “simulated annealing” algorithm has been performed.
Harmonic Analysis of the Polarization Reversal of the Rb2ZnCl4 Crystal in the Incommensurate Phase
Authors: Gorbatenko V. V. , Prasolov B. N. , Gorbatenko S. A. , Datsenko N. V.
Published: April 2024

The polarization reversal of Rb2ZnCl4 crystals in the incommensurate phase near a ferroelectric phase transition (PT) under the action of harmonic electric field has been studied using harmonic analysis. During polarization reversal of a test sample under the action of harmonic electric field, a PT induced by the electric field from the incommensurate phase to the ferroelectric phase and a PT from the field-induced ferroelectric phase back to the incommensurate phase occur. The study of the active and reactive contributions to the amplitudes of current density harmonics made it possible to determine the current values of harmonic electric field intensity at which the corresponding PTs occur.
DIFFRACTION OF X-RAYS IN CRYSTALS: A TENSOR APPROACH
Authors: Oreshko A. P. , Ovchinnikova E. N. , Dmitrienko V. E.
Published: April 2024

The use of X-ray synchrotron radiation makes it possible to observe the polarization, spectral, and angular dependences for diffraction reflections. Their theoretical study calls for application of a tensor approach to describe the interaction of X-rays with atoms of matter. Various representations of the tensor atomic scattering amplitude, results of experimental observations of the anisotropy of resonant X-ray scattering, and the relationship of the electric and magnetic multipole moments on atoms with the properties of forbidden resonant reflections are considered.
EVOLUTION OF THE DEFECT STRUCTURE OF Pd–11.3 at. % W ALLOY DURING RELAXATION AT MULTIPLE HYDROGENATION
Authors: Avdyukhina V. M. , Revkevich G. P.
Published: April 2024

The influence of the hydrogen and vacancies introduced into an alloy matrix as a result of electrolytic hydrogenation on the structural state of Pd–11.3 at % W alloy after fourfold hydrogenation has been studied. It is established that nonmonotonic changes in the sample defect structure are determined by the transformation of single vacancies into vacancy complexes (micropores and small dislocation loops), their decay during relaxation, and migration of vacancies from the matrix to the boundaries of coherent-scattering regions (CSRs) and backwards. The vacancy transformation rate into defect complexes depends on their concentration. Long-term relaxation of the alloy leads to almost complete transfer of vacancies from the matrix to the CSR boundaries. An interpretation of the obtained experimental data within the theory of development of hierarchical defect structures is proposed.
STRUCTURAL AND MAGNETIC TRANSITION IN MULTICOMPONENT R5X4 COMPOUNDS
Authors: Smirnov A. V. , Ovchenkova Yu. A. , Bogdanov A. E. , Morozkin A. V. , Tereshina I. S. , Nikitin S. A.
Published: April 2024

The structure, magnetic, magnetothermal, and magnetoelastic properties of Gd5Si2-xGe2-xIn2x (x = 0–0.1) intermetallic compounds have been studied in the region of magnetostructural phase transitions. It is shown that introduction of indium creates the effect of negative pressure, leading to a change in the critical temperature of the magnetic phase transition in the monoclinic phase of the compounds studied and to partial separation of the magnetic and structural phase transitions in them.
ON THE HISTORY OF THE BEGINNING OF X-RAY STRUCTURAL STUDIES AT MOSCOW UNIVERSITY
Authors: Oreshko A. P. , Yakuta A. A.
Published: April 2024

In the general context of the history of the origin of X-ray diffraction analysis in Russia, an interesting episode of the early stage of domestic X-ray structural studies—recording of “hole photographs” by Professor of Moscow University P.N. Lebedev in 1896, which can be interpreted as diffractograms of crystals—is highlighted. In authors’s opinion, specifically this scientific result is the starting point of the development of experimental X-ray methods of studying the crystal structure in Russia. Due to this, P.N. Lebedev can be considered as the inspirer of the famous pioneer scientific works of G.V. Wolf and N.E. Uspenskii in this area.
Magnetically Induced Effects in Ferroelectric Triglycine Sulfate Crystals with Chromium Impurity
Authors: Ivanova E. S. , Petrzhik E. A. , Eremeev A. P. , Gainutdinov R. V. , Lashkova A. K. , Ivanova A. G. , Volk T. R.
Published: April 2024

The influence of a permanent magnetic field on macro- and nanoscopic properties of triglycine sulfate (TGS) crystals with impurity chromium (TGS-Cr) has been investigated. This work continues the previous studies of magnetically induced effects in ferroelectrics. A specific feature of TGS crystals is the presence of a nanoscale relief on a polar (010) cleavage; this nanorelief is a qualitative characteristic of the crystal defect structure. It is shown that the exposure of a crystal in a magnetic field of 2 T leads to a change in its dielectric properties, accompanied by a long-term transformation of the nanorelief. The results obtained are indicative of a magnetically induced change in the defect crystal structure. A qualitative difference is found between the magnetically induced effects in TGS-Cr crystals and undoped TGS crystals. The relationship between the magnetically induced effects and structural defects is discussed.
Flat Spots Within Cenozoic Sediments of the Nansen Basin, Arctic Ocean: Indicators for Serpentinization, Gas Generation and Accumulation Processes
Authors: Sokolov S. Yu. , Geissler W. H. , Abramova A. S. , Ryzhova D. A. , Patina I. S.
Published: April 2024

Flat spot anomalies in the Quaternary part of the section of the Nansen Basin are imaged in seismic records and are interpreted to be related to gas-rich fluid accumulations. The flat spots are mainly located above basement highs between magnetic spreading anomalies C20 (~43 Ma) and C12 (~33 Ma). The complex morphometric analysis of flat spots show that serpentinization processes identified from modelling of gravity anomalies could be original gas source. This process also makes smoothing of the basement highs amplitudes. The depth of the top of the flat spots below the seafloor has an almost constant value of ~390 m indicating the ascent of gases from variable basement depths to a common subsurface fluid trap. The depth of the anomalies below the seafloor corresponds to a theoretical thickness of gas hydrate stability zone in the studied region. Gravity modeling along the Arktika-2011-03 section showed the position of the upper mantle blocks with lower (to 2.95 g/cm3) density within the highs of the acoustic basement. The flat spot anomalies occur above basement highs, below which blocks with lower density typical of serpentinized rocks are modeled. Thus, the serpentinization of the upper mantle ultramafic rocks is considered a main geochemical process, which can explain generation and accumulation of gas in oceanic abyss at a 1–3 km thick sedimentary cover, as well as small vertical movements of the basement blocks due to density reduction and expansion of serpentinized rock.
Are There Restrictions Related to the Land Plants Appearance for Reconstruction of the Different River’s Categories?
Authors: Maslov A. V. , Melnichuk O. Yu.
Published: April 2024

The article analyzes the position of the mudrock data points (points of individual and average samples) of almost 40 sedimentary sequences of the Neoproterozoic-Ordovician (the era of the absence of land plants) and the Devonian-Holocene (the time of the emergence and widespread distribution of land plants, the “green era”) on the diagrams (La/Yb)N–Eu/Eu*, (La/Yb)N–(Eu/Sm)N and (La/Yb)N–Th with classification fields of silty-pelitic particulate matter of estuarine parts of different modern rivers categories. No fundamental differences between the rivers of the “green era” and the pre-Silurian rivers have been revealed in this material. This suggest (in combination with other data) that in the absence of terrestrial vegetation (and not only in the Neoproterozoic–Ordovician), the categories of rivers that drained catchments of different square and composition and transported fine-grained particulate material to the shelf zones were not fundamentally different from those at present.
Biocidal Activity of Chitosan Asparaginate Nanoparticles
Authors: Shipovskaya A. B. , Lugovitskaya T. N. , Zudina I. V.
Published: April 2024

Abstract—The biological activity of chitosan asparaginate particles formed in the chitosan‒L-aspartic acid‒water system at the initial stage of phase separation was investigated. Cultivation of Staphylococcus aureus 209 P and Escherichia coli 113-13 in the medium supplemented with nanoparticles resulted in massive death of bacterial cultures. The biocidal activity against gram-positive bacteria was most pronounced. Biological tests revealed high biocompatibility of chitosan nanoparticles and their ability to accelerate the proliferative activity of the cultures of epidermal and epithelial cells. Our results indicate that chitosan asparaginate nanoparticles are promising for medico-biological and pharmaceutical applications.
Microbiological Characteristics of Three Stratified Lakes in the Nizhny Novgorod Region
Authors: Gorlenko V. M. , Vainshtein M. B.
Published: April 2024

Abstract—Three karst lakes were investigated in the Nizhny Novgorod region: Staropustynskie lakes Svyato and Nekrasov Bay and Lake Svetloyar. The studied lakes belonged to the mesotrophic-eutrophic polyhumous type and were characterized by stable stratification with signs of meromixia. Their water columns were divided into aerobic and anaerobic zones, with the bottom water containing sulfide. Fe(II) compounds were also present in the Staropustynskie lakes. In the Lake Nekrasov Bay, the mixolimnion showed a high rate of oxygenic photosynthesis, up to 1.2 µg С L–1 day–1, as well as a maximum of anoxygenic photosynthesis in the chemocline (0.030–0.706 µg С L–1 day–1) at a depth of 1.5–2.5 m. The peak of dark CO2 assimilation (0.146 µg С L–1 day–1) occurred at a depth of 1.5 m in the oxycline zone. Anoxygenic phototrophic bacteria (APB) were found in the Lakes Zaliv Nekrasova and Svyato at the boundary of light penetration. Green sulfur bacteria with short cell prosthecate outgrowths, “Ancalochloris sp.,” predominated. Consortia “Chlorochromatium aggregatum” and filamentous chlorobacteria “Chloronema giganteum” were also found, their cell sheaths accumulated ferric iron salts. In the Staropustynskie lakes, various morphotypes of iron bacteria formed clusters in the microaerobic zone. In Lake Svetloyar the chemocline was located at a depth of 16 m, outside the photic zone, and the conditions were unfavorable for APB growth. In the studied lakes, heterotrophic aerobic bacteria played the main role in the aerobic oxidation of sulfur compounds in the chemocline zone.
Analysis of the Key Determinants of Naphthalene Degradation by Rhodococcus pyridinivorans 5Ар
Authors: Larchenka A. Yu. , Mandryk M. I.
Published: April 2024

Abstract—Wild-type cells of Rhodococcus pyridinivorans 5Ар were found to be highly efficient naphthalene degraders, completely utilizing this compound (500 mg/L) after 3 days, and may be used for remediation of naphthalene-contaminated aquatic ecosystems. Inactivation of the biodegradation genes narAa (encoding the large subunit of naphthalene dioxygenase) and narB (encoding cis-naphthalene dihydrodiol dehydrogenase) resulted it the loss of ability to use naphthalene as the sole energy source, which indicated the absence in the genome of R. pyridinivorans 5Ар of the determinants responsible for alternative pathways of naphthalene oxidation. Moreover, narB inactivation resulted in accumulation of a polar colored compound (probably a product of primary naphthalene oxidation) in the medium.
Phylogenetic Diversity of Prokaryotic Communities of the Upper Sediment Layers of the Kandalaksha Gulf, White Sea
Authors: Badmadashiev D. V. , Stroeva A. R. , Klyukina A. A. , Poludetkina E. N. , Bonch-Osmolovskaya E. A.
Published: April 2024

Abstract—Microbial communities of the sediments of the Kandalaksha Gulf (White Sea) remain insufficiently studied. While the data on the rates of some microbial processes are available, very little is known of the microorganisms inhabiting these sediments. In the present work, high-throughput sequencing of variable regions of the 16S rRNA genes was used to characterize the microbial communities of 47 Kandalaksha Gulf sediment samples, collected at 10 cm below from the bottom surface. Pseudomonadota and Desulfobacterota were the most abundant phyla, which together comprised about a half of all prokaryotes. Determination of the dominant genus-level taxon proved impossible. The most represented chemoorganotrophic microorganisms were uncultured Sandaracinaceae (up to 10.8%) and Woeseia (up to 7.5%). Sulfate-reducing bacteria were important community components in the studied upper sediment layers, with uncultured groups SEEP-SRB1 (up to 7.0%) and Sva0081 (up to 5.9%) among the most abundant. In some samples, the genera Sulfurovum (up to 15.5%) and Thiohalophilus (up to 7.0%), involved in the oxidation of sulfur compounds, were important components of the community. Among the archaeal ASVs, the genus Nitrosopumilus, oxidizing ammonium to nitrite, exhibited the highest relative abundance (up to 6.9% of the total number of prokaryotes). Numerous sequences identified as the 16S rRNA gene fragments of chloroplasts were found in the samples, indicating that the rate of organic matter delivery to the upper sediment layers exceeded the rate of its degradation.
Methane Production in a Temperate Freshwater Lake during an Intense Cyanobacterial Bloom
Authors: Kallistova A. Yu. , Kosyakova A. I. , Rusanov I. I. , Kadnikov V. V. , Beletskii A. V. , Koval’ D. D. , Yusupov S. K. , Zekker I. , Pimenov N. V.
Published: April 2024

Abstract—Seasonal cyanobacterial blooms have a negative impact on freshwater ecosystems. The role of cyanobacteria in methane production and their relationship with methanogenic archaea are not yet well understood. The goal of the present work was to identify the features of methanogenesis in the water column and sediments of a profoundal part of the freshwater Lake Senezh (Moscow oblast) during a period of cyanobacteria over-bloom. Analytical, radiotracer, microscopic, molecular biological, and incubation techniques were used. Alkalization and oxygen oversaturation of the 0–2-m water layer were caused by intensive photosynthesis. The near-bottom water (4 m) was pH-neutral and hypoxic; the sediments were reduced. Methane was detected throughout the water column; its concentration in the surface water was an order of magnitude lower than in the near-bottom water and 4 orders of magnitude lower than in the sediments. Cyanobacteria of the species Microcystis aeruginosa predominated in the photic zone (up to 30% of the total number of the 16S rRNA gene fragments). The sequences of cyanobacteria and freshwater members of the SAR11 clade, which can potentially be involved in aerobic methanogenesis via decomposition of methylphosphonates (MPn), were also detected. The sequences of hydrogenotrophic methanogens of the genus Methanoregula, which are potentially capable of methanogenesis in cooperation with cyanobacteria, were revealed in oxygen-supersaturated water. Hydrogenotrophic and aceticlastic pathways of methanogenesis predominated in reduced sediments. Sequences of methanogens of to the orders Methanomicrobiales, Methanobacteriales, Methanosarciniales, and Methanomassiliicoccales were detected there. Cyanobacterial bloom promoted methanogenesis both in the photic zone of Lake Senezh (due to MPn decomposition and anaerobic methanogenesis in association with cyanobacterial aggregates) and in the near-bottom water and sediments (due to oxygen depletion and excessive release of substrates caused by sedimentation and degradation of cyanobacterial mortmass).
Anoxygenic Phototrophic Bacteria of the Meromictic Lake Bol’shie Khruslomeny (Oleniy Island, Kandalaksha Gulf, Murmansk Oblast, Russia)
Authors: Lunina O. N. , Grouzdev D. S. , Patsaeva S. V. , Zhil’tsova A. A. , Suzina N. E. , Krasnova E. D. , Voronov D. A. , Kokryatskaya N. M. , Veslopolova E. F. , Savvichev A. S.
Published: April 2024

Abstract—The composition and structure of the anoxygenic phototrophic bacterial (APB) community in the water column of Lake Bol’shie Khruslomeny during winter were investigated. The community developed at the depth of 4.25 m, and its activity during the ice-covered period was very low (6.2 µmol C L–1 day–1). The water in the zone of highest development of phototrophic bacteria was of an unusual lemon-yellow color, probably due to the production and accumulation of polysulfides. The near-bottom water was also of lemon-yellow color and was resistant to oxidation by the air oxygen. In the zone of peak APB development the content of BChl d from green-colored green sulfur bacteria was considerably higher than that of BChl e from brown-colored green sulfur bacteria: 77 and 23%, respectively. The cultures of green and purple sulfur bacteria were isolated from lake water, and their physiological and genetic characteristics were determined. Two strains of green sulfur bacteria (brown-colored BrKhr17 and green-colored GrKhr17) contained gas vacuoles in their cells. Phylogenetically they were most closely related to the green-colored strain Chlorobium phaeovibrioides DSM 265 and were identified as new Chlorobium phaeovibrioides strains.
Effect of Mutations in the Extracytosolic Domain of the Saccharomyces cerevisiae H+-ATPase on Its Activity and Regulation
Authors: Petrov V. V.
Published: April 2024

Abstract—Plasma membrane H+-ATPase (PMA1), the key enzyme of yeast metabolism, undergoes multiple phosphorylation during biogenesis and functioning. In the course of this process, the ATPase is getting activated (glucose effect). We have employed site-directed mutagenesis to determine the functional role of potentially phosphorylable amino acid residues located in the extracytosolic L9-10 loop (846-SENWTD). The mutant enzyme forms were expressed at the plasma membrane to examine the effect of substitutions on biogenesis and ATPase activity. Immunobloting revealed that the mutant ATPase expression was not significantly impaired. In the absence of glucose, basal activity of the mutant enzymes differed insignificantly from that of the wild type. At the same time, regulation of the mutant E847A, T850A, and D851A enzymes has been impaired; the level of enzyme activation by glucose was lower by 2.0−2.5-fold. On the contrary, the S846A mutant displayed elevated basal activity, maintaining the ability to undergo further activation. These data indicate that these residues (especially, Ser-846, Thr-850, and Asp-851) are essential for the normal functioning of the PMA1 and its regulation by glucose.
Attosecond Interferometry Involving Discrete States
Authors: Popova M. M , Yudin S. N , Gryzlova E. V , Kiselev M. D , Grum-Grzhimaylo A. N
Published: April 2024

In the paper we theoretically investigate the features of RABBITT (Reconstruction of Attosecond Beating By Interference of Two-photon Transitions) spectroscopy under conditions when transitions through discrete spectrum states play a significant role. Two approaches are applied in the article: the numerical solution of rate equations with continuum discretization and the perturbation theory up to the third order in amplitude. Both approaches use transition matrix elements and photoionization amplitudes obtained by the high-precision R-matrix method. Within the framework of these approaches, photoelectron spectra, the amplitude and phase of RABBITT oscillations were obtained, and the effect of the seed optical field intensity and detuning from a resonance upon excitation of discrete states was studied.
“Ideality” of a “Nonideal” Plasma
Authors: Khomkin A. L , Shumikhin A. S
Published: April 2024

Two chemical models of the plasma, which describe the mixture of free electrons, ions, and atoms, are derived using identity transformations based on the equation of state of the “physical” model of the plasma, in which an interacting mixture of electrons and nuclei (protons) us considered. These chemical models satisfy Onsager’s bookkeeping rule (the equation of state is independent on the position of the bookmark, viz., the boundary separating free and bound states). The effect of excited states of an atom on the equation of state and ionization equilibrium is analyzed. It is concluded that the contribution of the Debye attraction in traditional “chemical” models is overestimated. The relations obtained for the ionization potential lowering and the equations of state differ significantly from the generally accepted expressions and explain qualitatively the experimentally observed effect of “ideality” of a nonideal plasma.
BILATERAL SYNCHRONIZATION OF HIPPOCAMPAL THETA-OSCILLATIONS IN VITRO
Authors: Khalilov I. , Gainutdinov A. , Khazipov R.
Published: April 2024

Hippocampal theta oscillations are pivotal for hippocampal functions of spatial navigation, learning and memory. In the behaving animals in vivo, hippocampal theta oscillations display bilateral synchronization. Internally generated oscillations in the theta frequency range have also been described in the intact hippocampus preparation in vitro. How theta oscillations are synchronized between the left and right hippocampi remains elusive, however. We used preparation of the intact hippocampi interconnected by the ventral hippocampal commissure prepared from juvenile and adult mice and rats in vitro. Local field potentials and multiunit activity were recorded using extracellular electrodes from the pyramidal cell layer and stratum radiatum of the left and right hippocampi. Neuronal network activity in the left and right hippocampi was organized in theta oscillations, which strongly modulated neuronal firing of CA1 neurons. Both neuronal activity and field potential theta oscillations showed high levels of bilateral synchronization. Theta oscillations persisted on both sides, but their bilateral synchronization was eliminated after surgical cut of the ventral hippocampal commissure. Thus, theta oscillations are synchronized in the left and right hippocampi in vitro, and their bilateral synchronization is provided by the ventral commissural connections.
CHANGES IN THE NEUROGENIC NICHE OF THE RAT HIPPOCAMPUS UNDER HYPOXIC EXPOSURE
Authors: Fedorova E. N. , Voronkov D. N. , Egorova A. V. , Baranich T. I. , Glinkina V. V. , Germanova E. L. , Lukyanova L. D. , Sukhorukov V. S.
Published: April 2024

One of the most vulnerable brain structures to hypoxia is the hippocampus. Maintenance of the neurogenic niche cell pool in the subgranular zone of the hippocampus (SGZ) is provided by adaptive mechanisms. Among them are changes in the functional activity of mitochondrial respiratory chain complexes and the reaction of astroglia, which provides metabolic support for neurons. In order to study the dynamics of adaptive changes in neurons and glia in the dentate gyrus of the hippocampus under hypoxic conditions on a model of intermitten hypobaric hypoxia (5000 m, equivalent to 10.5% O2), with a single (60 min) and multiple (8 and 20 episodes) exposure in low-resistant rats, immunomorphological methods revealed the features of localization and content in the neurons of complex IV mitochondrial respiratory chain (MTCO1), astrocyte marker proteins glutamine synthetase (GS) and GFAP, and doublecortin (DCX) in immature neurons. With a single hypoxia, the content of MTCO1 in neurons significantly increased, and after eight exposures, the amount of glutamine synthetase (GS) in astrocytes of the dentate gyrus of the hippocampus increased. Changes in the content of GS were most pronounced in the processes of astrocytes, which indicates a redistribution of GS. The number of DCX+ neurons in the SGZ significantly decreased after 20 episodes of hypoxia. At the same time, DCX+ cells of glial morphology were found in the polymorphic layer, and staining for GFAP showed an increase in the number of astrocytes. This may be due to a shift in the direction of cell differentiation in the neurogenic niche. Thus, in hypoxia, at the initial stage, a functional restructuring of the respiratory chain of neurons of the granular layer occurs. Subsequently, it is noted by the activation of astrocytes that modulate glutamate metabolism. The presence of a relationship between the dynamics of adaptive reactions of energy exchange in neurons and glia and changes in neurogenesis during 20 episodes of hypoxia suggests that during long-term hypoxia, the differentiation of neural precursors of SGZ in the direction of astroglia occurs, however, this issue requires further study in order to more accurately determine the nature of DCX+ cells.
Reconstruction of the Metabolic Activity of the Intestinal Microbiota in Children and Adults with Obesity and its Relationship with the Representation of Alkylresorcinols in Feces
Authors: Zabolotneva A. A. , Itov A. B. , Grigorieva T. V. , Vasiliev I. Yu. , Roumiantsev S. A. , Gaponov A. M. , Shestopalov A. V.
Published: April 2024

The human body is a superorganism that depends on the trillions of microbial cells that inhabit it. Developing along with the host during evolution, the microbiota forms the phenotypes of our ancestors. Mutations that arose in the process of natural selection led to the joint evolution of the host organism and microbial cells to environmental conditions and the development of adaptability to this environment. The composition and metabolic activity of the intestinal microbiota are found in various manifestations of processes, as well as in the development of pathological conditions and dysmetabolic diseases, including obesity. Alkylresorcinols (AR) are biologically active polyphenolic compounds of microbial origin that have the ability to highly influence host metabolism and the composition of their microbiota. In the present study, we performed metagenomic sequencing of microbial DNA isolated from the stool samples of 401 metabolically healthy and obese children and adults, and also determined the content of various AR homologues in these samples. Based on high-throughput sequencing data, we reconstructed the metabolic potential of the intestinal microbiota and assessed the correlations between the content of various AR homologues and the abundance of microbial enzymes. Based on the results obtained, we observed the features of functional changes in the intestinal microbiota observed in adults and children with obesity.
PROTEASE ACTIVITY IN THE SMALL INTESTINE OF THE NORTHERN FULMAR FULMARUS GLACIALIS BY INFECTION OF TETRABOTHRIUS MINOR (CESTODA: TETRABOTHRIIDAE)
Authors: Kuklina M. M. , Kuklin V. V.
Published: April 2024

The effect of infection of Tetrabothrius minor (Cestoda: Tetrabothriidae) on the protease activity of the mucous membrane of the small intestine of the Northern Fulmar Fulmarus glacialis was studied. Aspects of changes in the activity of proteases and protease subclasses (metalloproteases, serine proteases and cysteine proteases) by infection of T. minor, and the ability of T. minor to inactivate proteases from the intestinal mucosa and commercial trypsin were evaluated. It has been established that in the localization of T. minor (proximal and medial sections of the small intestine) decreased protease activity due to a decrease in the activity of serine proteases and metalloproteases. The dependence of the decrease of protease activity in the mucous membrane of the small intestine of the host on the parameters of infection with cestodes was found – the higher the infection intensity of T. minor, the lower the activity of proteases, including metalloproteases and serine proteases. The ability of T. minor homogenates to inhibit the activity of proteases from the mucosa of Northern Fulmar and the activity of commercial trypsin of different concentrations was noted.
MEDIATORS OF THE SYMPATHETIC NERVOUS SYSTEM ATP AND NORADRENALINE IN THE MODULATION OF ANTIBODY FORMATION DURING DEEP COOLING OF THE ORGANISM
Authors: Meyta E. S. , Kozyreva T. V.
Published: April 2024

In experiments on rats, the participation of co-mediators of the sympathetic nervous system in the suppressive effect of deep cooling on the antibody-forming function of the spleen was studied. Studied: 1) the effect of deep cooling (decrease in deep temperature by 3–4°С), 2) the introduction of the mediator of the sympathetic nervous system norepinephrine (NE, 1 mg/ml), 3) its co-transmitter ATP (0.01 mg/ml and 10 mg/ml) and 4) P2X-purinergic receptor blocker PPADS on the number of antibody-forming cells of the spleen in response to immunization with sheep erythrocytes. Deep cooling as well as ATP inhibited, while NE stimulated antibody formation in the spleen. Blockade of P2X-purinergic receptors by PPADS stimulated antibody formation in the norm. Against the background of blockade of P2X-purinergic receptors, the inhibitory effect of ATP and deep cooling on antibody formation was not manifested. The results obtained indicate the opposite effects of co-mediators of the sympathetic nervous system on antibody formation in the spleen and suggest that the inhibitory effect of cold on antibody formation in the spleen occurs with the participation of ATP through P2X-purinergic receptors.
COMPARATIVE NEUROANATOMY OF DESCENDING NEURONS OF THE SUPRAESOPHAGEAL GANGLION OF COCKROACHES OF THE FAMILY BLABERIDAE (BLATTODEA)
Authors: Severina I. Yu. , Isavnina I. L.
Published: April 2024

A comparative study of the morphology of descending neurons connecting the supraesophageal ganglion and thoracic ganglia in cockroaches of the family Blaberidae, which differ in protective behavior and flight ability, was carried out. The neuronal structure of these families was compared with the descending neurons of the cockroach Periplaneta americana. The number, spatial distribution, and arrangement of axons and dendrites of descending neurons of cockroach Leucophaea maderae, Gromphadorhina portentosa, Blaberus craniifer, Nauphoeta cinerea (Blaberidae) were found to be similar. Neurons homologous to the ocellar, mechanosensory, and visual descending neurons described in the cockroach Periplaneta americana were found. It is suggested that during the evolution of the cockroach species, the adaptive behavior at danger was changed by transforming sensory inputs and motor responses, while the system of descending neurons remains stable.
NEUN EXPRESSION IN SPINAL NEURONS ORGANIZING PROJECTIONS TO THE CEREBELLUM
Authors: Veshchitskii A. A. , Pavlova N. V. , Shkorbatova P. Y. , Nikitina N. I. , Merkulyeva N. S.
Published: April 2024

We analyzed the peculiarities of the NeuN immunostaining of the cat spinal cord neurons located in four structures organizing projections to the cerebellum: the Clarke’s nucleus and border cells – in the L4 segment, the central cervical nucleus – in the C3 segment, and the Stilling’s nucleus – in the S2 segment. Morphometric and densitometric studies were carried out. It was shown that all neurons of interest have a striking feature: an extremely weak level of the cytoplasmic NeuN-staining, while maintaining a high level of the nuclear NeuN-staining. The soma size of neurons of interest was 1000–1850 mkm2, which is comparable to the size of another type of large neurons at slices – motoneurons (1140–1660 mkm2). Thus, we used a motoneuronal population of the corresponding segments to compare the values of optical density. The relative optical density of neurons of interest was several times lower than for the motoneurons (0.060 ± 0.030 vs 0.330 ± 0.127). There were no significant differences in optical density between different structures of interest. Given the morphological uniqueness and similarity of these four cell populations, we believe that the feature of NeuN protein expression can be used as a simple tool for the visualization of cells organizing projections to the cerebellum. It can be valuable both for targeted morphological examination and for histological control after a physiological experiment.
Topological Features of Parametric Structures of Bound Water
Authors: Lobyshev V. I. , Solovey A. B.
Published: April 2024

A review is presented of the authors’ own works on what they believe are the most important features of the model proposed by N.A. Bulienkov for parametric non-crystallographic structures of water associated with biopolymers. Characteristics of the internal parameters of bound water with a globular protein are considered, and the existence of twist baths in the structure of bound water is confirmed. The nature of water bonding with monosaccharides is analyzed. It is shown they complement parametric structures much more than they do the crystal structure of ice Ih. Important features of parametric structures include the possible formation of enantiomorphic structures and the accumulation of elastic stresses that can be used in the mechanochemical processes of molecular machines.
Synthesis of Ethylene–Vinyl Acetate Copolymers by Reversible Addition–Fragmentation Chain-Transfer Radical Polymerization
Authors: Karpov G. O. , Morontsev A. A. , Il'in S. O. , Sultanova M. U. , Samoylov V. O. , Bermeshev M. V.
Published: April 2024

Reversible addition–fragmentation chain-transfer radical copolymerization of ethylene with vinyl acetate in the presence of azobis(isobutyronitrile) and xanthate as a chain-transfer agent was studied. Products containing 12–42 mol % vinyl acetate units were prepared under varied reaction conditions. The glass transition points and degradation temperatures of the polymers were determined. The rheological properties of ethylene–vinyl acetate copolymers were studied in detail. The effect of additions of the copolymers synthesized on the rheological characteristics of diesel fuel was evaluated. The ethylene–vinyl acetate copolymers synthesized reduce the limiting filterability temperature of the diesel fuel.