bluuebunny/crossref_metadata_2025 huggingface dataset:
CALCIUM-ACCUMULATING ABILITY OF RAT LIVER MITOCHONDRIA DURING HYPOTHERMIA OF VARIOUS DURATIONS
Authors: Khizrieva S. I. , Khalilov R. A. , Dzhafarova A. M. , Abdullaev V. R.
Published: April 2024

Calcium is one of the most important intracellular messengers that regulate physiological and biochemical processes in the cell. Mitochondria are able to deposit calcium ions and are involved in the regulation of the calcium signal. Hypothermic conditions in homoiothermic animals can lead to disruption of this important function of mitochondria and pathological consequences. The aim of this study is to study the effects of moderate (30°C) hypothermia of varying duration on the calcium-accumulating capacity of rat liver mitochondria. The experiments were carried out on male rats Wistar. Hypothermia was induced by external cooling of the animals in Plexiglas chambers with a jacket through which cold water circulated. Mitochondria were isolated from the liver of decapitated rats by differential centrifugation. The calcium-accumulating capacity of mitochondria was assessed by the kinetics of calcium-induced swelling of mitochondria and their calcium capacity. A study of the kinetics of calcium-induced swelling of mitochondria showed that during short-term moderate (30°C) hypothermia, the rate of swelling of mitochondria decreases, prolongation of hypothermia to 1 h contributes to a further decrease in the swelling rate, and to 3 h, its normalization. A positive correlation was found between the rate of calcium-induced swelling and the calcium capacity of mitochondria (r = 0.79). Thus, with prolonged exposure to the cold factor in rats, a number of compensatory-adaptive reactions are activated. The decrease in the rate of Ca2+ – induced swelling and calcium capacity of mitochondria at the initial stages of hypothermia may be associated with the formation of mitochondrial pores and is reversible.
FUNCTIONAL SYNERGY ENSURES A TRAMPOLINE JUMP STOPPING
Authors: Moiseev S. A. , Mikhaylova E. A.
Published: April 2024

The paper considers the structure of intermuscular synergetic interaction that ensures the athlete’s body stopping on the trampoline after a jump. We compared the spatio-temporal characteristics of muscle synergies extracted from the skeletal muscles electroactivity amplitude and frequency of biopotentials data. The objective of the study was to find out whether the extracted kinematic modules represent the central mechanisms for the movement structure controlling as well as to determine the variables which should be stabilized by muscle synergies activity. The extraction of synergies was carried out using the matrix factorization method. It has been established that trampoline jump stopping can be performed using common patterns of muscle synergies spatio-temporal activation. The synergistic effects obtained using different approaches of instrumental assessment of skeletal muscle electroactivity probably reflect different control mechanisms implemented at different levels of the central nervous system. Muscle synergies are aimed at the stabilizing of the certain anthropometric points movement, as well as body segments, combined into kinematic modules. The structure of the kinematic modules themselves indicates the effective organization of intermuscular interaction, indirectly reflecting the central control mechanisms of complex multi-joint movement.
POSTСOLITIS ALTERATIONS IN NOCICEPTIVE PROPERTIES OF NEURONS IN THE RAT RAPHE MAGNUS AND DORSAL RAPHE NUCLEI
Authors: Sushkevich B. M. , Sivachenko I. B. , Lyubashina O. A.
Published: April 2024

Dysfunction of the brain serotonergic system is thought to play a leading role in the pathogenesis of chronic abdominal pain and comorbid somatic hyperalgesia, which disturb a significant proportion of patients with digestive tract diseases, even in remission. However, the specific changes in the serotonergic structures nociceptive properties that can be initiated by organic pathology and persist after its resolution remain unclear. The aim of our neurophysiological study on anesthetized rats – healthy and recovered from colitis – was to identify the alterations in the raphe magnus (RMg) and dorsal raphe (DR) nuclei neuronal responses to visceral (colorectal distension) and somatic (squeezing of the tail) noxious stimulations that persist after resolution of intestinal inflammation. It has been shown that both nuclei contain different groups of nociceptive neurons: 1) responding with activation only to colorectal distension (visceral); 2) excited only by tail squeezing (somatic); 3) reacting with excitation to the both irritations (general); 4) responding with discharge inhibition to any of the stimulations (inhibited). Compared with healthy animals, in RMg of colitis-exposed rats the number of the inhibited cells was increased and the total proportion of excited nociceptive neurons was reduced. Distension of the inflammation-undergone intestine caused enhanced RMg neuronal inhibition, whereas squeezing of the pathology-unaffected tail led to increased excitation of the RMg selective somatic and general nociceptive cells. In turn, in the DR of postcolitis rats the inhibited neuron proportion was reduced, while the increased population of excited neurons included fewer visceral and more somatic selective cells. This was accompanied by an increase in the selective reactions of the latter to somatic pain stimuli and by an increase in non-selective DR neuron excitation by visceral and somatic pain signals. The identified neuronal alterations can contribute to the postcolitis impairment of the studied raphe nuclei functions in the endogenous control of visceral and somatic pain sensitivity.
DISTRIBUTION OF PARVALBUMIN-EXPRESSING NEURONAL POPULATIONS IN THE CAT CERVICAL AND LUMBAR SPINAL CORD GRAY MATTER
Authors: Veshchitskii A. A. , Musienko P. E. , Merkulyeva N. S.
Published: April 2024

Parvalbumin is a classical marker of interneuronal populations in the central nervous system. Analyzing the cervical and lumbar spinal cord segments of cats (Felis catus), both individual cells and entire populations of neurons expressing parvalbumin were identified in most of the gray matter laminae. These populations have strict laminar and nuclear localization. Numerous neuronal clusters are located in the medial part of lamina V–VI and in laminae VII of cervical and lumbar enlargements. We believe that the first one located in segments C4–C8 and L4–L7 may participate in the modulatory mechanisms of locomotor activity via the convergence of cutaneous and proprioceptive afferentation from the limbs. Neuronal populations in lamina VII consist of Ia interneurons and Renshaw interneurons that participate in the motoneuron inhibition. Less numerous populations of parvalbumin-immunopositive cells found in laminae III possibly participated in the regulation of cutaneous sensitivity. Another population located in lamina VIII possibly forms commissural and propriospinal connections and participates in modulating the activity of motoneurons. Immunopositive interneurons also revealed in the precerebellar nuclei: central cervical nucleus and Clarke’s nucleus; unlike the general population of these nuclei, neurons revealed are interneurons. Scarce immunopositive cells are found in lamina I of L6–L7 segments, as well as in laminae II, IV, and X of all segments investigated.
THE INHIBITION OF AUTOPHAGY AND APOPTOSIS BY INSULIN AS A BASIS OF ITS NEUROPROTECTIVE ACTION ON RAT BRAIN CORTICAL NEURONS UNDER CONDITIONS OF OXIDATIVE STRESS IN VITRO
Authors: Zakharova I. O. , Bayunova L. V. , Avrova D. K. , Avrova N. F.
Published: April 2024

Insulin is one of the most promising neuroprotectors. A significant gap in understanding the mechanism of its action is the lack of data on whether it is able to prevent autophagic neuronal death. The aim of our work was to evaluate the contribution of autophagy and apoptosis to the death of rat cerebral cortex neurons in culture under oxidative stress and to study the ability of insulin to prevent this death and inhibit autophagy and apoptosis in neurons. The influence of hydrogen peroxide and insulin on the level of two main autophagy markers (LC3B-II and SQSTM1/p62) and apoptosis marker (cleaved сaspase-3) was studied. To assess the viability of neurons, the MTT test was used, and Western blotting was applied to measure the level of marker proteins. It was found that oxidative stress caused the activation of autophagy and apoptosis in neurons. This is manifested in a significant increase of the autophagy marker LC3B-II and apoptosis marker (cleaved сaspase-3) and in a decrease in the SQSTM1/p62 protein level. The content of SQSTM1/p62, which is involved in the formation of autophagosomes, decreases with the activation of autophagy, as this protein is degraded in lysosomes. Hydrogen peroxide causes autophagic and apoptotic death of neurons, as the inhibitors of autophagy (3-methyl adenine) and apoptosis (z-DEVD-FMK) were shown to increase the viability of neurons in conditions of oxidative stress. Insulin, in its turn, prevents the death of neurons and hinders autophagy, causing a decrease of the level of lipidated form LC3B-II and the increase of the SQSTM1/p62 protein level, it hinders apoptosis as well decreasing the level of cleaved caspase-3. The protective effect of insulin is mediated by the activation of specific signaling pathways associated with receptors of insulin and IGF-1, as the inhibitor of these receptors BMS-754807 completely blocks the neuroprotective effect of insulin. Thus, the pronounced activation of autophagy under oxidative stress is one of the causes of neuron death, and the protection of neurons by insulin is associated with the suppression of not only apoptotic, but also autophagic cell death.
ANALYSIS OF THE FUNCTIONAL STATE OF ASTROGLIA IN THE HIPPOCAMPUS OF RATS GENETICALLY PRONE TO AUDIOGENIC SEIZURES
Authors: Grigorieva Y. S. , Naumova A. A. , Nikolaeva S. D. , Glazova M. V.
Published: April 2024

It was shown that abnormalities in astrocyte functions can cause alterations in neuronal excitability and promote the development of epilepsy, however, this question claims further investigation. The aim of the present work was to analyze the functional state of astrocytes in the hippocampus of Krushinsky-Molodkina (KM) rats genetically predisposed to the reflex audiogenic seizures. Adult naïve animals with fully-established audiogenic sensitivity were recruited in our experiments. Rats of parental Wistar strain were used as a control. Obtained results revealed unchanged protein expression of such astocytic markers as GFAP, ALDH1L1, and NFIA suggesting the absence of the reactive astrogliosis in the hippocampus of KM rats. SPARC and aquaporin 4 expression also did not differ from the control indicating no violations in astroglia regulation of synaptogenesis and water balance. Analysis of glial proteins responsible for reuptake and metabolism of neurotransmitters revealed normal expression of GABA transporter GAT-3 and glutamine synthetase, while glutamate transporters EAAT1 and 2 were significantly elevated pointing on enhanced activity of glutamate removal from synapses. In addition, decreased expression of the key glycolytic enzyme aldolase C, probably, indicated insufficient activity of glucose metabolism in astrocytes. Thus, obtained data pointed on genetically determined alterations of astroglia functions in the hippocampus of rats with inherited reflex epilepsy.
PARAMETERS OF ENERGY METABOLISM AND ADENYLATE SYSTEM OF MYTILUS GALLOPROVINCIALIS TISSUES (LAMARCK. 1819) IN CONDITIONS OF MODERATE HYPOXIA
Authors: Kokhan A. S. , Soldatov A. A. , Golovina I. V. , Bogdanovich Yu. V. , Shalagina N. E. , Rychkova V. N.
Published: April 2024

The effect of moderate hypoxia on the processes of energy metabolism in the tissues (gills, hepatopancreas) of the Mediterranean mussel (Mytilus galloprovincialis, Lamarck, 1819) was studied experimentally. The control group of mollusks contained 6.8–6.9 mgO2 l–1, the experimental group at 1.9–2.0 mgO2 l–1. In both cases, the water temperature was 22 ± 1°C, the salinity was 17–18‰. The exposition – 72 hours. The oxygen content in the water was lowered by bubbling with nitrogen gas for 4–5 hours. In conditions of moderate hypoxia, a complex of reactions aimed at maintaining the energy status of tissues developed in the body of the Mediterranean mussel. Aerobic processes were clearly limited, as evidenced by a decrease in succinate dehydrogenase (SDH) activity. At the same time, the processes of anaerobic glycolysis intensified. The activity of aldolase, malate dehydrogenase (MDH) increased, the content of pyruvate in tissues increased. This was not accompanied by an increase in lactate dehydrogenase (LDH) activity and an increase in lactate content. The tissues retained their original energy status. The content of the ATP fraction remained at the level of control values, which reflected the adaptive orientation of the reorganization of tissue metabolism. The ability of hepatopancreas to accumulate ADP and AMP fractions from circulation systems under experimental hypoxic load was noted.
CORRECTION OF COGNITIVE IMPAIRMENTS AND SIGNALING PATHWAYS IN THE HIPPOCAMPUS OF RATS WITH TYPE 2 DIABETES MELLITUS USING INTRANASALLY ADMINISTERED INSULIN AND GANGLIOSIDES
Authors: Zakharova I. O. , Bayunova L. V. , Derkach K. V. , Shpakov A. O. , Avrova N. F.
Published: April 2024

Insulin controls both systemic glucose homeostasis and the functional activity of the brain. Insulin content and the activity of the insulin signaling system decreases in the brain in diabetes mellitus type 2 (DM2). It gives rise to disorders of energy metabolism, including hypometabolism of glucose in the brain, and to cognitive dysfunctions. The deficiency of hormone in the brain can be restored by intranasally administered insulin (IAI). It is also reasonable to use it in combination with substances with neuroprotective properties, including complex glycosphingolipids gangliosides, in order to increase the effectiveness of IAI for the correction of brain functions. Intranasal way of ganglioside delivery (IAG) to the brain can be explored as well. The aim of the research comprised the evaluation of efficiency of separate and combined IAI and IAG use to correct the cognitive impairment in Wistar rats with DM2 using the Morris water maze (MWM) and analysis of expression of proteins (BDNF, GLUT-1, GLUT-3, GLUT -4, GFAP, PSD95) and activity of protein kinases (Akt, GSK3β, ERK1/2) involved in learning and long-term memory formation in the hippocampus. IAI and IAG improved spatial orientation of rats with DM2in the MWM, and the effect of combined use of IAI and IAG was similar to the effect of each substance used separately. Owing to combined IAI and IAG the activity of effector protein kinases (Akt and ERK1/2) was maintained at the same level as in control rats while IAI monotherapy resulted in the reduced level of their phosphorylation. The level of GSK3β phosphorylation at Ser9 was also increased after combined treatments with insulin and gangliosides which is protective against tauropathy. Thus, the combined application of IAI and IAG improves the functional state of the components of the insulin system in the brain of rats with DM2, although it does not significantly enhance the effects of IAI on long-term memory.
ALLOSTERIC SITES AND ALLOSTERIC REGULATORS OF G-PROTEIN-COUPLED RECEPTORS: GRAY CARDINALS OF SIGNAL TRANSDUCTION
Authors: Shpakov A. O.
Published: April 2024

Membrane G protein-coupled receptors (GPCRs) are key components of most eukaryotic signaling systems, transducing external signals to intracellular effector proteins. Activation of GPCRs occurs through the specific binding of ligands of different nature to their orthosteric site. However, regulation of the affinity of an orthosteric agonist for the receptor, control of its effectiveness, and selection of the preferentially activated intracellular signaling cascade is carried out using allosteric mechanisms. This is due to the presence in GPCRs of many allosteric sites, which differ in structural and functional organization and topology in the receptor molecule, and are located in all its functional subdomains. The endogenous regulators of these sites are simple ions (Na+, Zn2+, Mg2+, Ca2+, Cl– and others), lipids (cholesterol, phospholipids, steroids), amino acids and their derivatives, polypeptides, as well as signaling proteins that form functionally active complexes with GPCRs (G proteins, β‑arrestins, RAMPs), and autoantibodies to the extracellular regions of GPCRs. Based on pharmacological activity, ligands of allosteric sites of GPCRs are divided into positive, negative or silent modulators of the effects of orthosteric agonists, as well as full and inverse agonists or neutral antagonists, which affect the basal activity of the receptor in the absence of an orthosteric agonist, although combining the properties of a modulator and an agonist is also possible. The multiplicity of allosteric sites and allosteric regulators, complex interactions between them, and the involvement of allosteric mechanisms in the formation of receptor complexes play a key role in fine-tuning the functional activity of signaling cascades, in biased agonism, and predetermine the processes of receptor desensitization and the fate of the receptor complex after hormonal signal transduction. The review summarizes and analyzes current concepts and new trends in the field of studying the allosteric regulation of GPCRs, the localization and functional role of allosteric sites, and their endogenous and synthetic ligands. As an example, synthetic allosteric regulators of the receptors of thyroid-stimulating and luteinizing hormones, as potential drugs for the correction of endocrine disorders, are discussed in detail.
Crystal Structure and Properties of Complex Oxides (Nd,Ba)(Co,Fe)O3–δ
Authors: Aksenova T. V. , Volkova N. E. , Legonkova V. S. , Cherepanov V. A.
Published: April 2024

The homogeneity ranges and crystal structure of solid solutions of Nd1−x1BaxCo1−y1FeyO3−δ3 composition were detected. Depending on introduced barium concentration Nd1−x1BaxCo1−y1FeyO3−δ3 oxides have been crystallized in the orthorhombically distorted (x = 0.05, sp. gr. Pbnm), cubic (0.6 ≤ x ≤ 0.9, sp. gr. Pm-3m) perovskite structure or double perovskite structure NdBaCo2−x2FexO5+δ5 (0.0 ≤ x ≤ 1.4, sp. gr. P4/mmm). The dependencies of unit cell parameters versus composition of the Nd1−x1BaxCo1−y1FeyO3−δ3 solid solutions were obtained. It is shown that the values of oxygen nonstoichiometry in Nd1−x1BaxCo1−y1FeyO3−δ3, determined by a thermogravimetric method within the temperature range 298–1373 K in air, increased with the raise of barium and cobalt content. Average values of thermal expansion coefficients for the Nd1−x1BaxCo1−y1FeyO3−δ3 oxides (0.8 ≤ x ≤ 0.9 and 0.7 ≤ y ≤ 0.9) visibly increased with temperature from (13.5–14.5) × 10–6 K–1 at 300–700 K up to (23.2–26.2) × 10–6 K–1 at 700–1373 K.
Effect of UV Radiation on Dissipative Processes in Polyacrylates of Different Elasticities
Authors: Aslamazova T. R. , Kotenev V. A. , Lomovskaya N. Yu. , Lomovskoi V. A. , Khlebnikova O. A. , Tsivadze A. Yu.
Published: April 2024

Dynamic mechanical relaxation spectroscopy is used to study the relaxation behavior of elastic alkyl(met) polymers. The items of interest are acrylates on metal substrates before and after UV irradiation of different durations. Analysis is based on comparing the intensity of local dissipative relaxation in irradiated and non-irradiated polymers, along with their glass transition temperatures and elastic properties.
Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate
Authors: Dobrydnev S. V. , Aleksandrova O. A. , Novikov A. N.
Published: April 2024

The degree of dissolution of nickel(II) hydroxide in mixtures of aqueous solutions of ammonia and ammonium bicarbonate has been studied. The equilibrium between the solid and liquid phases was reached in 11–12 h after the start of experiment. Nickel(II) hydroxide showed higher solubility in the ammonia–carbonate mixture compared with aqueous solutions of ammonia and ammonium bicarbonate. The ratio of ammonium bicarbonate and ammonia concentrations in solution at which the highest degree of dissolution of Ni(OH)2 was achieved was determined. An analytical description of the ion-molecular equilibrium in the ammonia– carbonate mixture was given, and the equilibrium concentrations of molecules and ions in the system were calculated. A stoichiometric equation describing the dissolution of nickel(II) hydroxide in an ammonia–carbonate solution was given.
From Hydrophylicity to Surface Hydrophobicity: Variation of the Wettability of a Material on a Substrate Due to Local Vibrational Effects during Its Interface Synthesis
Authors: Golubina E. N. , Kizim N. F.
Published: April 2024

A system of an aqueous solution of a lanthanide salt di-(2-ethylhexyl)phosphoric acid in a diluent (heptane, toluene, carbon tetrachloride) is used to show that the local vibration on the interfacial layer in a system of two immiscible liquids during interfacial synthesis can produce a qualitative change in the wettability of the substrate onto which the material of interfacial formations is transferred. This makes the surface hydrophobic or hydrophilic due to different structuring, as in the lotus leaf effect. By varying the composition of the system, the conditions of the process, and the parameters of the external force field, a material with a given angle of contact (30° to 163°) can be obtained, improving the consumer qualities of its carrier.
Activation of Viscous Flows of Water–Acetone–Methyl Ethyl Ketone Solutions with High Contents of Water, Compared to Water–Alcohol–Acetone Solutions
Authors: Grineva O. V.
Published: April 2024

Values of kinematic viscosity and density are determined for water–acetone–methyl ethyl ketone solutions for the first time in the region of high contents of water and the 20–40°C range of temperatures. Results are used to calculate the molar kinematic viscosity (νm), the Gibbs energy of viscous flow activation (ΔG≠νΔ), and the entropy of viscous flow activation. The viscometric characteristics of this system are compared to those of water–ethanol–acetone, water–2-propanol–acetone, and water–2-butanol–acetone systems studied earlier. Dependences on the concentration of one organic component at a fixed content of a second are presented for different properties. The viscometric parameters of ternary solutions with methyl ethyl ketone, calculated based on size/molecular weight of the components (νm and ΔG≠νΔ), are close to those obtained for solutions with ethanol but notably higher for solutions with 2-propanol and 2-butanol. It is concluded that molecules participating in the formation of intermolecular hydrogen bonds as proton donors (alcohols) raises viscosity more than an increase in size/mass (methyl ethyl ketone). Different ways of calculating the entropy of viscous flow activation (ΔS≠νΔ) are compared on the basis of literature data. It is found that ΔS≠νΔ is higher than that of water in the studied range of concentrations of the ternary water–acetone–methyl ethyl ketone system, which is also typical of other aqueous solutions.
Constants of Stability of Cobalt(II) Complexes with Glycylglycinate Ions in Aqueous Acetone Solutions
Authors: Isaeva V. A. , Molchanov A. S. , Shishkin M. V. , Sharnin V. A.
Published: April 2024

Potentiometric titration is used to determine constants of stability of cobalt(II) glycylglycinate complexes at a temperature of 298 K and the ionic strength of 0.1 M solutions in aqueous acetone solutions. It is established that in contrast to aqueous solutions, cobalt(II) mono-glycylglycinates, bis-glycylglycinates, and tris-ligand complexes can all form in water–acetone mixtures. The stability of cobalt(II) complexes with glycylglycinate ions grows along with the concentration of acetone in a solution.
Potassium–Sodium Ceramics Modified with Metal Oxide Additives: Synthesis, Microstructure, and Properties
Authors: Kaleva G. M. , Politova E. D. , Mosunov A. V. , Stefanovich S. Yu. , Sadovskaya N. V.
Published: April 2024

Single phase ceramic samples of new compounds (1 − x)(K0.5Na0.5)NbO3−xLa(Ag0.5Sb0.5)O3 (x = 0–0.15), modified by metal oxide additives ZnO, CuO, and MnO2, are prepared via a solid state reaction. The crystal structure, microstructure, and dielectric and ferroelectric properties of the samples are studied. It is established that a phase with a perovskite structure and an orthorhombic unit cell formed in each sample. Ferroelectric phase transitions are confirmed via dielectric spectroscopy. Generation of the second harmonic is observed, along with a drop in the temperature of transitions from the ferroelectric orthorhombic phase to the ferroelectric tetragonal phase, and then to the cubic paraelectric phase.
Structure and Properties of Composite Materials Sintered at High Pressure and Reinforced with Amorphous Boron Particles
Authors: Lukina I. N. , Chernogorova O. P. , Drozdova E. I. , Ekimov E. A.
Published: April 2024

Metal matrix composite materials (CMs) reinforced with boron particles are synthesized from powders of amorphous boron and metal (Ni, Ti) at a pressure of 8 GPa and temperatures of 500–1000°C. It is established that amorphous boron crystallizes during synthesis at temperatures above 800°С. Amorphous boron particles are characterized by a hardness of ~30 GPa, an indentation modulus of elasticity of up to 270 GPa, and an elastic recovery of more than 60%. The patterns of boride formation during high-pressure synthesis are studied. It is shown that the wear resistance of a Ni–B CM synthesized at 600°С grows by more than 30 times, relative to the wear resistance of pure nickel. Reinforcing titanium with 30% amorphous boron increases wear resistance by more than two orders of magnitude, but the coefficient of friction of CMs is reduced slightly.
Preparing Thin Gallium Sulphide Films via PECVD and Studying Their Properties
Authors: Mochalov L. A. , Kudryashov M. A. , Logunov A. A. , Vshivtsev M. A. , Prokhorov I. O. , Vorotyntsev V. M. , Malyshev V. M. , Sazanova T. S. , Kudryashova Yu. P. , Bulanov E. N. , Knyazev A. V.
Published: April 2024

Thin films of GaSх are obtained via plasma-enhanced chemical vapor deposition (PECVD) for the first time, while high-purity volatile derivatives of the corresponding macrocomponents (gallium chloride (GaCl3) and hydrogen sulfide (H2S)) are used as the initial materials. It is found that the nonequilibrium low-temperature plasma of an HF discharge (40.68 MHz) at a reduced pressure (0.01 Torr) is the initiator of chemical transformations. Components of reactive plasma formed in the gas phase are studied via optical emission spectroscopy (OES). Structural and electrophysical properties of the obtained materials are studied as well.
Membranes Based on PVdF–HFP and Alkylammonium Protic Ionic Liquids: Thermal and Transport Properties
Authors: Shmukler L. E. , Fadeeva Yu. A. , Stel’makh N. M. , Safonova L. P.
Published: April 2024

Casting from a solution is used to obtain proton-conducting membranes based on a poly(vinylidenefluoride-co-hexafluoropropylene) copolymer doped with diethylammonium hydrogen sulfate and diethylammonium mesylate with different levels of doping. An IR spectroscopic study is performed, and the phase behavior of the obtained membranes, their thermal and electrochemical stability, and specific electrical conductivity are investigated. It is established that doping protic ionic liquids into PVdF-HFP copolymer reduces the degree of its crystallinity. It has been shown that all membranes are thermally stable up to 290–300°C, and their conductivity at 145°C varies from 1.6 to 10.4 mS cm–1, depending on the level of doping.
Low-Temperature Three-Channel Gas Analyzers in Optical Monitoring of Fire Hazard Liquefied Natural Gas Outflows
Authors: Zagnit’ko A. V. , Zaretskii N. P. , Matsukov I. D. , Sal’nikov S. E. , Pimenov V. V. , Fedin D. Yu. , Alekseev V. I.
Published: April 2024

A network of three-channel low-temperature infrared-optical gas analyzers with a response time of 1 s is developed for detecting explosive and fire hazardous concentrations of gasified liquefied natural gas (LNG) at temperatures up to 150 K. Their characteristics are described in an analysis of its large-scale emissions into the atmosphere. It is shown that during pulsed LNG emissions in the form of submerged jets and spills on standard concrete and water, large-scale areas of mixtures of air, methane, and light alkane vapors form with an explosive concentration that fluctuates in time and volume. The evaporation of cryogenic methane droplets with diameters of more than 0.1 mm in air and methane vapor from temperatures T = 150–290 K has been studied theoretically and experimentally.
Reductive Treatment of δ-MnO2 with Sodium Borohydride: Method for Increasing the Electrode Material Capacitance
Authors: Arkhipova E. A. , Ivanov A. S. , Nikolenko S. K. , Maslakov K. I. , Savilov S. V. , Aldoshin S. M.
Published: April 2024

The effect of reductive treatment on the phase composition, morphology, and electrochemical parameters of δ-MnO2 produced by the hydrothermal method from KMnO4 at a temperature of 160°C in the presence of HNO3 was studied. δ-MnO2 processing with 3 M NaBH4 aqueous solution leads to partial reduction of Mn(IV) to Mn(III) and Mn(II). The electrochemical characteristics of the obtained electrode materials were examined by cyclic voltammetry, galvanostatic charge–discharge measurements, and impedance spectroscopy. Reductive treatment increases the specific capacitance of δ-MnO2 in 1 M Na2SO4 up to 204 F g–1 at a current density of 0.1 A g–1, and also reduces diffusion limitations during cycling due to an increase in the specific surface area. The loss of specific capacitance after 2000 charge–discharge cycles does not exceed 2.6%, which confirms the high electrochemical stability of the obtained electrode materials.
Electrochemical Determination of Streptomycin on an Electrode Modified with a Composite of Graphene Oxide and Gold–Nickel Binary System
Authors: Shaydarova L. G. , Pozdnyak A. A. , Gedmina A. V. , Chelnokova I. A. , Murdasova D. A. , Budnikov G. K.
Published: April 2024

A procedure was suggested for voltammetric determination of streptomycin from the catalytic current on a glassy carbon electrode with a composite based on reduced graphene oxide and gold–nickel binary system. The working conditions of the electrode modification (volume of the graphene oxide and chitosan suspension, duration of the electrolytic reduction of immobilized graphene oxide and electrodeposition of the gold–nickel binary system) and the conditions for recording the catalytic current in the flow injection system were determined. The procedure for streptomycin determination in a flow, compared to the determination under stationary conditions, is more sensitive, reproducible, and rapid. The streptomycin detection limit was 0.45 nmol, and the productive capacity of the analysis was 60 samples per hour. The streptomycin determination procedure passed trials in analysis of cow milk.
Coagulating Ability of N,N-Diallyl-N,N-dimethylammonium Chloride-based Copolymers in the Separation of Rubbers of Various Grades
Authors: Churilina E. V. , Nikulin S. S. , Verezhnikov V. N. , Shatalov G. V. , Sergeev M. V.
Published: April 2024

The study assessed the coagulating ability of copolymers N,N-diallyl-N,N-dimethylammonium chloride with acrylamide and maleic acid when separating styrene/butadiene and nitrile/butadiene rubbers from latexes. The effect of the consumption of these cationic polymers, the concentration of the dispersed phase and temperature on the completeness of rubber separation was studied. It was established that the completeness of styrene/butadiene rubber separation from latex is achieved at a 0.5 kg t–1 consumption of cationic copolymer with acrylamide, and that of butadiene/nitrile rubber is achieved at 22 kg t–1. The introduction of maleic acid units into the cationic copolymer ensures the complete separation of styrene/butadiene and nitrile/butadiene rubber from latex at a consumption of 0.3 and 8 kg t–1, respectively. Vulcanizates obtained from rubbers isolated using copolymers meet the requirements of State Standard GOST 15627–2019.
Preparation, Structure, and Properties of Chitosan Microtubes
Authors: Shipovskaya A. B. , Gegel' N. O. , Babicheva T. S. , Golyadkina A. A.
Published: April 2024

Procedures were developed for forming hollow cylindrical structures with the wall thickness in the micrometer range (microtubes) from chitosan solutions in citric, lactic, and glycolic acids. The procedures are based on the phase-transfer neutralization induced by the transport of ions (hereinafter, ion-induced reaction), occurring at the liquid–liquid or solid–liquid interface, namely, on the polymer-analogous conversion of the salt form of the polymer to the base form in a NaOH or triethanolamine medium or formation of a water-insoluble polyelectrolyte complex with sodium dodecylbenzenesulfonate. Comparative analysis of the dependences of the morphological, structural, elastoplastic, physicomechanical, and biological properties of the structures on the reaction conditions and kind of the organic acid and neutralizing agent was made. The microtubes prepared from a chitosan solution in glycolic acid by ion-induced neutralization at the solid–liquid interface in a NaOH or triethanolamine medium exhibit the optimum levels of strength and elasticity, comparable with those of a fragment of human carotid artery and xenopericardial patch. The hemo- and biocompatibility and controlled biodegradation of these materials make them promising as analogs of biodegradable blood vessel implants.
Microstructure and Thermal and Rheological Properties of Low-Molecular-Mass Ethylene–Vinyl Acetate Copolymer
Authors: Morontsev A. A. , Karpov G. O. , Il'in S. O. , Dement'ev K. I. , Bermeshev M. V.
Published: April 2024

The microstructure of low-molecular-mass ethylene–vinyl acetate copolymers was studied by 1Н and 13С NMR spectroscopy. The vinyl acetate mole fraction, chain branching, and mean lengths of ethylene and vinyl acetate blocks were determined. The thermal properties of ethylene–vinyl acetate copolymers were studied by differential scanning calorimetry and thermogravimetric analysis, and the crystalline characteristics, by X-ray diffraction analysis. The degree of crystallinity of the copolymer decreases with an increase in the fraction of the polar comonomer. Rheological studies show that ethylene–vinyl acetate copolymers at room temperature tend to microphase segregation and form a microphase structural network.
Optimization of Arabinogalactan Sulfation in Process Scaling
Authors: Kostyro Ya. A.
Published: April 2024

To ensure the safety of the arabinogalactan sulfation process, the thermal effect of the reaction (148.26 kJ) was determined by the thermal flux balance method. The dependence of the dynamic viscosity of the reaction medium on the way of introducing the sulfating agent and on its particle size was studied by phase rheology. The stirring process was calculated to substantiate the optimum stirrer design and determine the quality parameters of stirring of the reaction medium. The data obtained allow optimization of the process for producing Agsular® substance in scaling of the production technology.
Calculation and Simulation of Flowsheets for Processing Flue Gases from Thermal Power Plants to Methanol
Authors: Galanova E. G , Magomedova M. V. , Chistyakov K. A. , Afokin M. I. , Bazhenov S. D.
Published: April 2024

Several flowsheets for processing flue gases from thermal power plants to commercial-quality methanol, differing in the steps of producing the feedstock for the methanol synthesis, were considered. The dependence of the methanol yield, energy efficiency, and carbon footprint of the technology as a whole (from the step of СО2 capture from flue gases to the step of methanol extraction) on the composition of flue gases (СО2 concentration) and temperature of their flow was studied. The option of processing flue gases with high initial flow temperature using the flowsheet involving high-temperature steps of СО2 separation and electrolysis was considered. Taking into account the recovery of the heat from flows and steam generation, this flowsheet has high efficiency.
Magnesium Hydrogen-generating Materials and a Hydrogen Generation Setup
Authors: Arbuzov A. A. , Mozhzhukhin S. A. , Lototskiy M. V. , Tarasov B. P.
Published: April 2024

The reaction of composites consisting of MgH2 and a graphene-like or nickel–graphene material with water or citric acid solutions of various concentrations was studied. The composites were prepared by mechanochemical treatment in a hydrogen atmosphere. The reaction of an aqueous citric acid solution with the composites is fast: 98% hydrogen yield is reached at the MgH2 : citric acid molar ratio of 1 : 1. A setup for preparing compressed hydrogen from the composites was developed. It can be used in autonomous mobile installations for hydrogen generation under high pressure, followed by filling balloons.
Low-Temperature Composite CO2 Sorbents Based on Amine-Containing Compounds
Authors: Sheshkovas A. Zh. , Veselovskaya Zh. V. , Selishchev D. S. , Kozlov D. V.
Published: April 2024

The use of technologies based on combustion of carbon-containing fossil fuel leads to emission of large amounts of CO2, one of the main greenhouse gases, into the atmosphere. To reduce the CO2 level in the atmosphere, systems for CO2 sorption from various gas sources are being developed. The systems allowing the CO2 sorption and desorption at low temperatures (25–200°С) are of most interest. Most frequently, such systems are composite materials consisting of a porous support and a CO2 chemisorbent dispersed on it. Low-volatile amine-containing compounds are the most promising among organic chemisorbents. Classification of the amine-containing sorbents with respect to the preparation procedure is discussed. The procedures include impregnation, covalent grafting, and in situ polymerization on the support surface. The impregnation procedure is simple and cheap in implementation. The sorption characteristics of materials prepared by impregnation depend on the efficiency of the dispersion of the active component, which is determined by the characteristics of the support pore structure, in particular, by the ability of the pore surface for chemical or electrostatic interaction with the supported amine-containing compound. The covalent grafting is based on immobilization of alkoxyaminosilanes on the surface of porous silica materials. The supports for implementing this approach should contain a large amount of silanol groups on the surface and should have the pore size sufficient for the efficient transport of CO2 molecules to amino groups. The main drawback of the grafting method is low thickness of the amine-containing component layers obtained. In situ polymerization is used for preparing materials with high content of grafted functional groups. Provided that the blocking of support pores is excluded in the course of in situ polymerization, materials of this type exhibit the highest sorption capacity for CO2.
Impact of Precursor Granulometry on the Synthesis of Calcium-Aluminate Phases
Authors: Trubitsyn M. A. , Furda L. V. , Yapryntsev M. N. , Volovicheva N. A. , Mikhaylyukova M. O.
Published: April 2024

Calcium aluminate phases were synthesized in the range 950–1450°C from available raw materials: carbonate rock and metallurgical alumina, predominantly in the γ form with different grain sizes. The calculations of the amount of raw materials were based on the requirement to ensure the chemical composition of the product: Al2O3 71–72 and CaO 27–28 wt %. The designed phase composition of the samples is 65 wt % CaAl2O4 and 35 wt % CaAl4O7. When alumina with a grain size of 90 μm and a spherulitic microstructure is introduced into the reaction, the formation of the CaAl2O4 and CaAl4O7 phases mainly occurs in the range of 1250–1350°C, and phase equilibrium is established at 1450°C. Reducing the size of γ-alumina grains to 10 μm and destroying their spherulitic microstructure shifts the formation of calcium aluminates to the temperature range below 1250°C, and also significantly increases the rate of synthesis of target products.
Homogeneous Equilibrium in Solutions with Limited Solubility of Components
Authors: Zevatskiy Yu. E.
Published: April 2024

The equilibrium position of a homogeneous reversible chemical reaction in solutions in the case when at least one component is of limited solubility in the reaction mixture differs from the state when all components are unlimitedly soluble. Calculations of the minimum Gibbs energy in the model of extremely dilute solutions, according to Le Chatelier’s principle allow formulating the rule: if all other things being equal and unaltered, an increase in the solubility of a component in the reaction mixture shifts the position of homogeneous equilibrium towards an increase in its content. The results obtained can be generalized to the kinetics of reactions in terms of the influence of solvents. The theoretical foundations of a new lever for optimization of chemical processes were developed.
Influence of the Moisture Content of Mesoporous Silica Gel on the Efficiency of the Chromatographic Recovery of Vanadyl Petroporphyrins with Benzene
Authors: Mironov N. A. , Tazeeva E. G. , Milordov D. V. , Yakubova S. G. , Yakubov M. R.
Published: April 2024

Benzene proved to be a more effective eluent compared to chlorinated organic solvents traditionally used for chromatographic recovery of vanadyl petroporphyrins from the dimethylformamide (DMF) extract of asphaltenes on a column packed with mesoporous silica gel. Low eluting power of benzene can be compensated by moistening of the silica gel adsorbent. An increase in the silica gel moisture content from 0 to 7.7% does not lead to a decrease in the efficiency of the separation of vanadyl porphyrins from nonporphyrin components but leads to a tenfold decrease in the eluent consumption. A decrease in the eluent flow rate from 0.8 to 0.12 mL min–1 (per gram of the adsorbent) leads to a 1.5-fold increase in the yield of vanadyl porphyrins of required purity. An increase in the adsorbate : adsorbent weight ratio from 1 : 833 to 1 : 83 does not lead to a decrease in the efficiency of the vanadyl porphyrin recovery. Elution with benzene under optimum conditions (adsorbent moisture content, eluent flow rate, adsorbate : adsorbent ratio) allows the recovery of 3 times larger amount of petroleum vanadyl porphyrins from the DMF extract of asphaltenes than when using chloroform and dried silica gel under equal other conditions.
Reactive Extrusion of Multifunctional Conducting Nanocomposites Based on Polypropylene Random Copolymer and Ethylene–Propylene Block Copolymer
Authors: Kakhramanov N. T. , Allakhverdieva Kh. V.
Published: April 2024

The effect of extrusion parameters on the characteristics of nanocomposites based on polypropylene random copolymer and ethylene–propylene block copolymer with carbon black and aluminum nanoparticles and calcium stearate was studied. Printex XE 2-B carbon black with the nanoparticle size of 18–20 nm was used. Exхelor PO 1020 compatibilizer was used for improving the compatibility of the blend components. Introduction of the above fillers allows obtaining a multifunctional nanocomposite that exhibits high levels of electrical conductivity, adhesion to metals, and thermal conductivity and can be processed by pressure casting and extrusion. The effect of the temperature conditions in the extruder material cylinder on the breaking stress and relative elongation of the nanocomposites was considered. The optimum temperature conditions of the extrusion, ensuring relatively high properties of the composite, were determined.
MIGRATORY CONNECTIONS IN WATERFOWL OF NORTHERN WESTERN SIBERIA, BASED ON RING-RECOVERY DATA
Authors: Panov I. N. , Kharitonov S. P. , Rozenfeld S. B. , Litvin K. E.
Published: April 2024

Migratory connections in waterfowl in the north of Western Siberia are discussed as based on ring recoveries from the database of the Bird Ringing Center of Russia, A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences. Altogether, 3531 recoveries from waterfowl of 29 species were used. The waterfowl in the region are characterized by exceptionally wide migratory connections, occurring in different seasons in most regions of the Old World within the Northern Hemisphere: from Iceland to the Japanese Islands and from West Africa to the Indian Subcontinent and the Yangtze River basin. The long-distance flights of birds to molting sites, the interannual change of nesting grounds and wintering regions, as well as the distribution on wintering grounds are discussed. Ten wintering regions have been allocated. The available material on the migration of waterfowl is evaluated from the viewpoint of completing the description of their seasonal distribution and its significance in the study of ecological connections of the territory of Western Siberia.
DISTRIBUTION AND RANGE STRUCTURE OF THE BRISTLETAIL GENUS ALLOPSONTUS SILV. (MACHILIDAE, MICROCORYPHIA)
Authors: Kaplin V. G.
Published: April 2024

The distributions of all eight subgenera and 52 species of the large southern Palearctic genus Allopsontus are analyzed. Species of this genus are found mainly in open foothill and mountain habitats with steppe vegetation and rocky-gravelly substrates. The general distribution range of the genus lies within the Scythian (steppe), Sahara-Gobi (desert), European and Stenopean (broadleaf’s), as well as Mediterranean-Macaronesian and Ortrian (evergreen) regions of the Palearctic. The species of the nominative and most species-rich subgenus occupy most of the range of the genus. Phylogenetically, from the relatively primitive subgenus Kaplinilis to the most specialized subgenus Machilanus, there is a tendency to shift the ranges of the subgenera from north to south, which is accompanied by a shift in their habitats from the lower mountain belts to the upper ones with a rocky substrate. The center of subgeneric diversity of the genus Allopsontus is located in the mountains of the older Ural-Mongolian mountain system, whence its species could have spread to the mountains of the younger Alpine-Himalayan belt.
EXTENDED MOLTING AGAINST THE BACKGROUND OF CLIMATE WARMING IS THE MAIN REASON FOR THE EMERGENCE OF THE BAIKAL SEAL (PUSA SIBIRICA, PINNIPEDIA) TO COASTAL ROOKERIES
Authors: Petrov E. A. , Kupchinsky A. B.
Published: April 2024

An analysis of the video films taken at a Baikal seal rookery in 2011–2021 on the Long Island, Ushkany Islands, northern Lake Baikal, showed that the total number and time of the emergence of animals on the shore were determined by the time of the disappearance of ice in the northern part of the lake. Yet, regardless of the ice regime, a significant part of the animals (up to 80%) leaving land continued molting. At the same time, the nature of molting (its topology) was disturbed in the vast majority of cases, molting being diffuse in character, often with elements of pathological manifestations. The number of molting individuals (in %) decreased by autumn, but still remained large, even though such dynamics were observed not every year. Incomplete molting did not interfere with animals’ fattening, as most seals were well or very well fed (especially by autumn), with individuals leaving the rookery immediately after the disappearance of ice also being well fat. At the same time, animals in coastal haulouts showed pathologies of the skin and hairline annually, the occurrence of which was probably associated, among other things, with abnormal molting. A large number of animals seem to leave for wintering with an incomplete molt, with their further fate being unknown. The data obtained indicate that disturbing the dormancy of molting seals on rookeries is inadmissible, since the excessive factor of disturbance (observed at the rookery at the present time) can play significant negative roles through affecting the physical condition (health) of animals.