bluuebunny/crossref_metadata_2025 huggingface dataset:
The Plutonium Uptake by Plants (Review)
Authors: Shupik A. A. , Edomskaya M. A. , Synzynys B. I. , Shavrina K. E.
Published: April 2024

The article summarizes information on the accumulation of plutonium by plants. The factors influencing the process of plutonium migration in the “soil-plant” system are considered. A review is given of plutonium transfer factors by plants as quantitative indicators of migration. It is shown that the plutonium transfer factors by plants are very variable and cover six orders of magnitude. It is noted that for a territory subject to global fallout, the transfer factors of plutonium are significantly lower than for a polluted one. For this, special publications of the IAEA, publications on the study of the accumulation of plutonium for background territories and territories subject to radioactive contamination, were considered. The data on the influx of plutonium into various agricultural crops grown at the Semipalatinsk test site are given. Transfer factors of plutonium by agricultural crops are in the range n × 10–5–n × 10–1 for the territory of the Semipalatinsk test site. Literature data on the accumulation of plutonium by wild vegetation growing in the Chernobyl fallout territory, etc. are considered. Transfer factors of plutonium by herbaceous vegetation for the territory of Chernobyl fallout are at the level of n × 10–2. The article summarizes and presents information on the plutonium transfer factors by various plants organs. In general, based on the analysis of literature data, the plutonium transfer factors are in the range n × 10–7–n × 10–1.
On the Relationship of Natural and Modified Radioresistance with Mast Cell Reactivity
Authors: Ushakov I. B. , Kordenko A. N.
Published: April 2024

This study was caused by accumulation of the data concerning: 1) relationship between the general reactivity of the body and radioresistance; 2) essential role of mast cells in the formation of radiobiological effects; 3) significant individual features of body radioresistance. Purpose of the study was to identify the relationship of radioresistance indicators with the state of body reactivity, manifested by constitutionally determined features of connective tissue mast cells. Natural radioresistance and modifying effect of hypoxia, hyperoxia and indralin radioprotector were considered. The study was performed on 369 white male rats weighing 215–240 g. To determine the individual characteristics of radioresistance, total and cranio-caudal irradiation of animals was performed. As a hypoxic test, hypoxic gas mixture with 8% oxygen content was used. The criteria of radioresistance were 5- and 30-day survival, weight loss, early transient disability. Index of reactivity of skin mast cells was considered as the diagnostic sign. Relationship features between the level of mast cell reactivity and radioresistance indicators were revealed. It has been shown that the minimum level of natural radioresistance is typical for animals with a high index of mast cell response to hypoxia. The modifying effect of hypoxia during irradiation was manifested in all animals. Also, the highest level of modified radioresistance was observed in rats with average values of the mast cell reactivity index. At the same time, When indralin was used, its radioprotective effect was most pronounced in the group of animals with the maximum reaction of mast cells. The radiomodifying effect of oxygen is mostly expressed in rats with the maximum values of the mast cell reactivity index and is characterized by a decrease in 5-day survival and average life expectancy. The relationship between the characteristics of mast cells and radioresistance can serve as a basis for the development of methods for predicting individual natural and modified radioresistance.
Outlooks of Using Small Extracellular Vesicles as a Transport Vehicle through the Blood–Brain Barrier
Authors: Khaspekov L. G. , Yakovlev A. A.
Published: April 2024

The review summarizes the results of recent studies on the mechanisms mediating the crossing by small extracellular vesicles through blood-brain barrier (BBB). The kinds of vesicular transport through the BBB, including receptor-mediated and adsorptive-mediated transcytosis, are considered. The possibilities of optimizing the penetration of vesicles into the parenchyma of the brain through the BBB are shown.
Neurospecific Proteins as Transdiagnostic Markers of Affective Disorders
Authors: Levchuk L. A. , Bokhan N. A. , Ivanova S. A.
Published: April 2024

Mental disorders have many differences in pathogenesis and clinical symptoms, however, they are characterized by general neurobiological processes that occur with a damage of nervous tissue, disturbance of blood-brain barrier, inclusion of autoimmune mechanisms, neurodegenerative processes and release of neurospecific proteins into the liquor and into the blood. We presented a review of current literature devoted to studies of the role of neurospecific proteins in the pathogenesis of affective disorders. Glial fibrillar acidic protein (GFAP), S-100 protein, myelin basic protein (MBP), and neuron specific enolase (NSE) reflect damage of neurons, astrocytes and oligodendrocytes in depressive disorders and they could be considered as transdiagnostic nonspecific markers of affective disorders.
Role of Brain Monoamines in the Formation of Audiogenic Myoclonic Seizures in Krushinsky–Molodkina Rats
Authors: Litvinova S. A. , Voronina T. A. , Kudrin V. S. , Narkevich V. B. , Surina N. M. , Poletaeva I. I. , Fedotova I. B.
Published: April 2024

The results demonstrate and confirm the significant role of monoamine imbalance in the ictogenesis of Krushinsky–Molodkina rats with genetically determined audiogenic epilepsy and in the development of audiogenic kindling (AuK) in them. The experiments were carried out on rats of the Krushinsky–Molodkina (KM) line without sound stimulation (KM-background) and after the development of AuK (KM-AuK). The control group was rats of line “0”, in which convulsions in response to sound were completely absent. AuK was generated using 20-fold sound stimulation (120 dB). Neurochemical analysis was performed by HPLC/ED in the frontal cortex, hippocampus, hypothalamus, nucleus accumbens, and brainstem. It has been established that AuK in KM rats leads to the appearance of myoclonic and attenuation of stem convulsions, which is accompanied by a change in the functional activity of the noradrenergic and serotonergic systems of the brain. KM rats exhibiting tonic convulsions in the “background” have a low content of norepinephrine in the hippocampus and hypothalamus, and when audiogenic myoclonic convulsions develop, norepinephrine deficiency is observed in the frontal cortex. After the formation of AuK, the excessively intense serotonin metabolism revealed in KM slows down in the hippocampus, nucleus accumbens, and, especially, in the brainstem, and the serotonin deficiency in the striatum also disappears. The peculiarities of norepinephrine metabolism in KM rats before and after AuK emphasize the important role of the cortex in the development of myoclonic convulsions, and of the hippocampus and hypothalamus in the implementation of stem convulsions. Excessive functional activity of the serotonergic system, revealed in KM “background” rats, slows down in a number of brain structures during the production of AuK.
The Effect of Piracetam and Noopept on NMDA and 5-HT2A Receptors in the Brain of Mice with Congenital β-Arrestin Deficiency
Authors: Firstova Yu. Yu. , Kovalev G. I.
Published: April 2024

Based on the special role of the signal protein β-arrestin in the processes of neuronal plasticity and receptor activation, the effects of the nootropic drugs Piracetam (2-oxo-1-pyrrodinyl-acetamide, UCB 6215, 200 mg/kg, I.P.) and Noopept (ethyl ether N-phenyl-acetyl-L-prolyl-glycine, GVS-111, 0.5 mg/kg, I.P.) in mice with congenital deficiency of β-arrestin-2 (BARR2-KO mice) and in mice of the C57Bl/6 line (wild type for the BARR2-KO, WT line). Serotonin (5-HT2A) and NMDA-receptors of the brain, which play an important role in cognitive processes, but differ in the type of structure and activation mechanism, were chosen as the object of the study. Using radioligand analysis, it was found that the BARR2-KO mouse line differs from the C57Bl/6 mice by a significantly higher density (Bmax) of both NMDA-receptors in the hippocampus (by 85%) and 5-HT2A -receptors in the cerebral cortex (by 54%). Interestingly, both drugs after chronic administration increased the number of NMDA-receptors in the hippocampus both in the BARR2-KO strain (Piracetam – by 76%, Noopept – by 78%) and in the C57Bl/6 strain (Piracetam – by 112%, Noopept – by 49%). At the same time, the effect of both drugs on the density of serotonin 5-HT2A-receptors in BARR2-KO and C57Bl/6 mice was not the same. In particular, Piracetam caused an increase in the density of 5-HT2A-receptors in the cerebral cortex of BARR2-KO mice by 31%, whereas on the comparison line C57Bl/6 neither Piracetam nor Noopept had any effect. Thus, the absence of the β-arrestin signaling protein in BARR2-KO mice is accompanied by an increase in the density of NMDA- and 5-HT2A-receptors in the brain. At the same time, the different effects of Piracetam and Noopept on NMDA receptors both in the line with congenital β‑arrestin deficiency and in the line with normal expression may indicate that this type of receptor is a common primary target for the action of nootropics of various structures.
Estimated Gene Expression of SNARE Proteins in Hyppocampus of Rats after Modelled Spaceflight
Authors: Perevezentsev A. A. , Lebedeva-Georgievskaya K. B. , Kuznetsova O. S. , Shtemberg A. S.
Published: April 2024

Our recent researches demonstrate shifts in brain activity of rats, both at behavioral and biochemical levels, induced by one of modeled impacts of interplanetary spaceflight, i.e. space radiation. Thus emerges a question, whether such shifts occur in molecular underlying processes of brain function. We have investigated the gene expression for proteins of SNARE (soluble NSF attachment receptor), responsible for fusion of transport vesicles with terminal membranes. Our result is an evidence of changes in some SNARE elements after irradiation and an indirect evidence of a link between nature of such changes and animal nervous system typology. Thus, in order, impairments of brain activity after model irradiation compared to such of an interplanetary flight are observed at every level of nervous system structure.
Effect of Low Molecular Weight Nerve Growth Factor Mimetic GK-2 on Cognitive Function and Synaptic Transmission in Hippocampal Slices
Authors: Volkova A. A. , Povarnina P. Yu. , Rogozin P. D. , Kondratenko R. V. , Sharonova I. N. , Kamensky A. A. , Skrebitsky V. G.
Published: April 2024

Nerve growth factor (NGF) contributes to the proliferation, differentiation and maintenance of the viability and functioning of peripheral and central neurons. At the Research Zakusov Institute of Pharmacology a dimeric dipeptide mimetic of the NGF loop 4 bis(monosuccinyl-L-glutamyl-L-lysine) hexamethylenediamide (GK-2) was created. GK-2 activates PI3K/AKT and PLC-γ1 signaling cascades, without affecting MAPK/ERK, and appears to have procognitive properties. In the present study, we investigated the mnemotropic effects of GK-2 with a single intraperitoneal dose of 0.1, 0.5 and 5.0 mg/kg in the novel object recognition test in rats. GK-2 at a dose of 0.5 mg/kg statistically significantly improved the long-term memory of animals. In experiments on the rat hippocampal acute slices, we evaluated the effects of GK-2 on synaptic transmission and its plastic properties in the synaptic system Schaffer collaterals − CA1 pyramidal cell.
Cognitive Impairment and Nootropic Drugs: Mechanism of Action and Spectrum of Effects
Authors: Voronina T. A.
Published: April 2024

The review provides information about the features of cognitive dysfunctions that occur in various diseases and conditions, and data on the history of the creation and characteristic features of nootropics. The review presents the mechanisms of action and the spectrum of pharmacological effects of nootropic drugs from various groups: drugs that affect brain metabolism, neurotransmitter systems (cholinergic, glutamatergic, gabaergic and others), cerebral vasodilators, neuropeptides and their analogues, antioxidants, membrane protectors and others. The free radical and mitochondrial concepts of aging and the possibility of using nootropics for the correction of cognitive impairments arising from aging, dementia and other neurodegenerative diseases are considered.
Features of Changes in Exogenous Heat Shock Proteins (HSP 27 and HSP 70) in Patients with Occupational Nervous System Pathology
Authors: Bodienkova G. M. , Boklazhenko E. V.
Published: April 2024

The aim of the study was to identify and compare changes in serum concentrations of heat shock proteins (HSP 27 and HSP 27) in patients with occupational nervous system pathology induced by exposure to physical and chemical factors. Patients with sensorineural hearing loss (SHL), chronic mercury intoxication (CMI), vibration disease (VD) formed both under the influence of local vibration and combined exposure to general and local vibration were examined. As a result of comparative evaluation and analysis of serum concentrations of heat shock proteins, peculiarities in their change were revealed. In individuals with SHL and VD due to local vibration exposure, a decrease in serum HSP 70 concentration was recorded, and in patients with CMI and VD due to combined local and general vibration exposure, high HSP 27 concentrations were recorded. The examination of patients in the linked sample at 3 years showed the absence of statistically significant differences and the preservation of changes in the content of exogenous HSPs, which confirms the progressive course of these diseases. The conjugation of the number of T-lymphocyte and B-cells subpopulations with the change in serum HSP concentrations was established, which confirms the role of HSP 27 and 70 in the regulation of the immune response in VD and allows them to be regarded as markers of cellular and tissue damage in the chronic course of diseases.
Metabolic Plasticity of a Developing and Aging Brain
Authors: Salmina A. B.
Published: April 2024

Brain plasticity is a fundamental phenomenon based on various types of intercellular interactions (synaptic activity, neuritogenesis, synaptogenesis and elimination of synapses, neuron-glia interactions), development, differentiation, migration of newly-born cells and cell death (neurogenesis/gliogenesis and neuronal or glial cell death, angiogenesis and regression of cerebral microvessels), adaptation of tissue metabolism to changing environmental conditions. In this review, we discuss our own data and available literature in the context of regulation of certain types of energy metabolism (glycolysis, mitochondrial respiration) in neuronal, glial, and endothelial cells, the signaling functions of metabolites in nervous tissue, the mechanisms of establishment of cerebral insulin resistance, pseudohypoxia and associated neuroinflammation in brain pathology, as well as some prospects for detecting novel molecular markers of pathobiochemical processes associated with impaired metabolic plasticity in the developing and aging brain.
State-of-the-Art: the Use of Extracellular Vesicles and Preparations Based on Them for Neuroprotection and Stimulation of Brain Tissue Regeneration after Injury
Authors: Basalova N. A. , Dzhauari S. S. , Yurshev Yu. A. , Primak A. L. , Efimenko A. Yu. , Tkachuk V. A. , Karagyaur M. N.
Published: April 2024

Extracellular vesicles are macromolecular complexes produced by virtually all types of eukaryotic and prokaryotic cells. According to modern concepts, they allow cells to exchange information, regulate each other’s activity and coordinate their actions during the complex processes of development, maintaining homeostasis, tissue regeneration, etc. Extracellular vesicles have a number of unique properties: the ability to accumulate certain types of proteins and nucleic acids, protect them from degradation and ensure their delivery to target cells, which can be used to create biomimetic approaches to the therapy of a wide range of diseases. The composition of vesicles, the preference for docking with a particular cell type, and ultimately their therapeutic potential are very flexible parameters and are highly dependent on the type and properties of the producer cell culture, as well as cultivation conditions. This review gives an idea of the state and prospects of the therapeutic strategies implied the application of extracellular vesicles for neuroprotection and stimulation of brain tissue regeneration after injury, and also considers existing clinical studies which use extracellular vesicles in the field of neurology and neurosurgery. Particular attention in the review is given to new promising approaches to increasing the production of extracellular vesicles, manipulating their contents, and increasing the efficiency of targeted docking in order to increase their therapeutic activity and specificity.
Role of VEGF in Angiogenesis and Motor Recovery after Ischemic Stroke
Authors: Kucherova K. S. , Koroleva E. S. , Alifirova V. M.
Published: April 2024

Recent scientific studies indicate that angiogenesis and neurogenesis are interrelated processes that determine the functional outcome after ischemic stroke. This literature review presents current data on neurovascular interactions in ischemic stroke, describes the role of the family of vascular endothelial growth factors in the regulation of angiogenesis and neurogenesis, which play a leading role in neuronal survival and neuroplasticity. The authors searched the literature on the pathophysiological role of VEGF in acute cerebral ischemia using the relevant keywords into the PubMed and Google Scholar search engines, as well as Scopus, Web of Science, MedLine, The Cochrane Library, EMBASE, Global Health, CyberLeninka, eLibrary, and other databases. Clinical studies evaluating the role of VEGF in ischemic stroke are in most cases based on animal models, and their results are ambiguous, which is determined by the versatility of its action. VEGF is an important regulator of angiogenesis, neuroprotection and neurogenesis, but its negative effect has also been proven in the form of an increase in the permeability of the BBB and, as a consequence, cerebral edema, as well as the activation of inflammatory processes. Thus, further study of VEGF is needed to determine its role in functional recovery after ischemic stroke.
T-Cell Aspects of Some Neurological Diseases
Authors: Kvichansky A. A. , Bolshakov A. P.
Published: April 2024

Polyneuropathies are a heterogeneous group of immune-mediated diseases, among which Guillain–Barré syndrome and chronic inflammatory demyelinating polyneuropathy are the most frequent. On the contrary, amyotrophic lateral sclerosis is most often considered as a disease, whose development is practically not associated with changes in the function of the immune system. This review summarizes the latest data on changes in the T-lymphocyte subpopulations and their function in the blood and cerebrospinal fluid in the aforementioned diseases. These data suggest that regulatory T cells and NKT cells may play an important role in the development of the discussed pathologies. We stress the necessity of accumulation and analysis of data on T-cell subpopulations, as well as the sequence of T-cell receptors, HLA, and CD1 in patients for the development of approaches to the diagnosis and possible therapy of these diseases.
Quantitative Characteristics of Small Extracellular Vesicles from the Blood of Patients with Non-Suicidal Self-Harm
Authors: Mishin I. N. , Zinchuk M. S. , Druzhkova T. A. , Gulyaeva N. V. , Guekht A. B. , Yakovlev A. A.
Published: April 2024

Objective of the study – determination of quantitative characteristics of small extracellular vesicles (sEV) in the blood of patients with non-suicidal self-injury (NSSI) and comparison of the concentration and size of sEV’s in patients with major depressive disorder (MDD) with and without NSSI, as well as an assessment of the relationship between the sizes and concentrations of sEV in the sample with such parameters as the severity of situational and personal anxiety, depression and suicidal risk. The study included 28 patients (11 m./17 f.) with a current episode of major depression and at least five episodes of NSSI in the last 12 months (main group, mean age 28.3 years) and 28 patients with major depression identical in sex and age without NSSI throughout life (comparison group). Patient mental status was assessed using the MINI interview, the Beck Depression Inventory II (BDI II), and the Spielberger Anxiety Scale. Isolation of sEV from blood was carried out using polyethylene glycol (PEG) precipitation and gel filtration. The size and concentration of isolated particles were estimated using dynamic light scattering (DLS) and nanoparticle tracking analysis (ATN). The groups differed significantly in the severity of depression according to the BDI-II questionnaire, the Spielberger Situational Anxiety Scale, and the Spielberger Personality Anxiety Scale. The assessment of suicidal risk, carried out according to the corresponding module of the MINI questionnaire, revealed a significantly larger number of participants with medium and high suicidal risk in the group of patients with NSSI. The sEV fraction was isolated from the blood of the patients of the main group and the comparison group. There were no differences in the concentration and size of sEV between groups of patients with depression with and without NSSI. In our study, the dependence of the concentration and size of sEV on the severity of depression, situational and personal anxiety, and the severity of suicidal risk wasn’t revealed. Conclusion: NSSI in individuals with major depressive disorder is associated with a more severe course of the disorder (greater severity of depression, situational and personal anxiety), as well as a higher risk of suicide. Our study did not reveal any differences in the quantitative characteristics of sEV in patients with a depressive episode with and without NSSI. Future studies should focus on investigating the structural differences and functional features of sEV in NSSI.
The Role of Nonspecific Inflammation in the Development of Diabetic Polyneuropathy
Authors: Shchepankevich L. A. , Pervuninskaya M. A.
Published: April 2024

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes mellitus type 2 (DM2) and is associated with significant morbidity and mortality. The pathophysiological mechanisms leading to the development of DPN have not been fully studied and are still debatable. Currently, immune-mediated mechanisms of its development are being discussed. The aim of this study was to estimate the content of TNF-α in the blood serum of patients with DM2 complicated by DPN and to assess the significance of this factor in the development and progression of DPN. An open comparative study was conducted with the participation of 83 patients with DM2 of different duration. In patients with clinical manifestations of DPN and long-term course of DM2 (group 2), the level of TNF-α was significantly higher compared to patients with DM2 and duration of DPN less than 2 years, and both studied groups of patients with DM2 and DPN had a high level of TNF-α in comparison with the control group. The results obtained indicate a more aggressive immune-mediated process that develops with a longer duration of DM2 and makes a negative contribution to the functioning of the peripheral nerve fiber.
Change in the Charge State of MOS Structures with a Radiation-Induced Charge under High-Field Injection of Electrons
Authors: Andreev D. V. , Bondarenko G. G. , Andreev V. V.
Published: April 2024

The influence of high-field electron injection modes on the charge state and defectiveness of metal–oxide–semiconductor (MOS) structures after irradiation is studied. It is shown that to erase the radiation-induced positive charge accumulated in the SiO2 film of MOS structures, it is necessary to apply high-field Fowler–Nordheim tunnel injection of electrons in electric field that do not cause the hole generation. It has been established that erasure of the radiation-induced positive charge in the SiO2 film of MOS structure and the generation of new interface traps are mainly determined by the magnitude of the charge injected into the dielectric. It has been found that, upon annihilation of the holes trapped in SiO2 as a result of the interaction with the injected electrons, a significant increase in the number of the interface traps is observed, which significantly exceeds the number of interface traps arising upon annealing of a radiation-induced positive charge at room temperature. A model is proposed that describes the annihilation of a radiation-induced positive charge upon interaction with injected electrons.
Increasing the Thermal Stability of the Submicrocrystalline Nickel Surface under High-Fluence Ion Irradiation
Authors: Borisov A. M. , Mashkova E. S. , Ovchinnikov M. A. , Khisamov R. K. , Musabirov I. I. , Shayakhmetov R. U. , Mulyukov R. R.
Published: April 2024

The results of an experimental study of the effect of high-fluence ion irradiation on the thermal stability of the microstructure and surface relief of submicrocrystalline nickel are presented and discussed. The submicron structure of nickel was obtained during the severe plastic deformation by torsion under high pressure of 6 GPa. Irradiation with argon ions with an energy of 30 keV and a dose of 3 × 1018 cm–2 was carried out. Ion irradiation of submicrocrystalline nickel was shown to lead to the formation of a cone-shaped surface morphology. This morphology is thermally stable to a temperature of at least 500°C. Using etching with a focused gallium ion beam with an energy of 30 keV, a surface layer 10 µm thick of irradiated submicrocrystalline nickel annealed at 500°С was studied. It was found that the ion-induced cone-shaped morphology of the surface could be preserved during annealing and block grain growth in the near-surface layer.
On Equilibrium Configurations of Charged Ions in Planar Systems with Circular Symmetry
Authors: Nikonov E. G. , Nazmitdinov R. G. , Glukhovtsev P. I.
Published: April 2024

The problem of finding equilibrium configurations of one-component charged particles, induced by external electrostatic fields in planar systems, is a subject of active studies in fundamental as well in experimental investigations. In this paper the results of numerical analysis of the equilibrium configurations of charged particles (electrons), confined in a circular region by an infinite external potential at its boundary are presented. Equilibrium configurations with minimal energy are searched by means of the hybrid numerical algorithm. The algorithm is based on the interpolation formulas, that are obtained from the analysis of the equilibrium configurations for an arbitrary finite number of charged particles, provided by the variational principle, developed in the circular model. The solution of the nonlinear equations of the circular model yields the formation of the shell structure which is composed of the series of rings. Each ring contains a certain number of particles, which decreases as one moves from the boundary ring to the central one. The number of rings depends on the total number of electrons. The interpolation formulas provide the initial configurations for the molecular dynamics calculations. Our results demonstrate a significant efficiency of using the method of classical molecular dynamics (MD) when using the interpolation formulas in comparison with algorithms based on Monte Carlo methods and global optimization. This approach makes it possible to significantly increase the speed at which an equilibrium configuration is reached for an arbitrarily chosen number of particles compared to the Metropolis annealing simulation algorithm and other algorithms based on global optimization methods.
Nuclear Physical Study of the Composition of Near-Surface Layers of Rapidly Solidified Foils of Al–Mg–Li–Sc–Zr Alloy after Thermal Treatment
Authors: Stoliar I. A. , Shepelevich V. G. , Tashlykova-Bushkevich I. I. , Wendler E.
Published: April 2024

The influence of thermal treatment on the lithium distribution over the depth of near-surface layers was studied for rapidly solidified foils of industrial Al–Mg–Li–Sc–Zr alloy (1421) produced by ultra-rapid quenching from the molten state using unilateral cooling on the internal surface of rotating copper drum. It was found by electron backscatter diffraction that as-cast foils had a micrograin structure with an average grain size of 12 μm and a texture [111]. Using atomic force microscopy, it was determined that the air-side surface was characterized by a fine cellular structure, which was also observed in the area of caverns and cavities on the drum-side surface. The surface roughness of the foils was from 44 to 57 nm. The patterns of the lithium depth distribution in annealed specimens were established by nuclear reaction analysis using a proton-induced reaction (p, α). It was found that during low-temperature annealing, the near-surface and deep layers of the samples were depleted in lithium, which was evenly distributed over the foil depth. A multiple increase in the lithium concentration found in the near-surface region of the foils was established during high temperature annealing, resulting in the formation of a composition-gradient foil structure. The effect of structure and phase changes caused by the decomposition of a supersaturated solid solution with the precipitation of lithium-containing phases on the behavior of lithium in the annealing temperature range 150–380°C is discussed.
Crystallographic Texture and Functional Properties of Powder Titanium Alloys after Thermomechanical Treatment
Authors: Markova G. V. , Ivankina T. I. , Levin D. M. , Volodko S. S.
Published: April 2024

A relationship has been established between the crystallographic texture developed during various thermomechanical treatments and the functional properties of titanium-based alloys, in particular, titanium nickelide obtained by sintering calcium hydride powder. Thermomechanical treatment of sintered workpieces was carried out by rotary forging, radial shear rolling, or extrusion. The temperature of the last stage of deformation in all cases was 900°C. The neutron diffraction analysis of the samples was performed on a texture diffractometer SKAT at JINR (Dubna, Russia). The projection plane of the experimental pole figures was perpendicular to the sample axis and the deformation axis. The shape memory characteristics were determined by torsion deformation on wire samples cut from rods along the axis. The texture is most fully demonstrated by the sample after extrusion: the volume fraction of textured grains reaches 85%, and the maximum pole density is 2.76 m.r.d. (multiple of a random distribution). The functional properties under torsion deformation γstr = 2–16% are studied. Extruded samples and samples subjected to radial shear rolling demonstrate the best superelasticity in the austenitic phase γsuperеlast = 15% and maximum values of critical stresses γcr = 15%, starting from which the deformation becomes irreversible. A relationship between the sharpness of the crystallographic texture and the functional properties of the TiNi alloy after thermomechanical treatment has been revealed.
Simulation of Optical Parameters of Scintillation Position-Sensitive Detectors with Organic Light Guide
Authors: Trunov D. N. , Marin V. N. , Sadykov R. A. , Altynbaev E. V. , Glushkova T. I.
Published: April 2024

A new method for determining the coordinates in position-sensitive detectors with an organic fiber and silicon photomultipliers is described. This method differs from previously used spectrum-shifting fibers or an array of light-sensitive elements. It is based on the absorption of photons in the volume of the fiber and the reduction in the number of photons. Depending on the path length, the number of photons incident on the surface of the silicon photomultiplier varies. The optical parameters of a one-dimensional position-sensitive detector are simulated and the effect of the fiber coating on the amount of light is shown. Simulation of a two-dimensional position-sensitive detector of two types has been also carried out, optical parameters and intensity ratios from different ends of the fiber have been determined. A technique for obtaining maps of intensity ratios and features of their use for determining the coordinates are described. The main features of the manufacture of this type detectors and their influence on the resolution of the final detector are outlined.
Resonance Effects in Photoemission Spectroscopy of Rare-Earths in Intermetallic Compound La0.73Tb0.27Mn2Si2
Authors: Ponomareva E. A. , Korkh Yu. V. , Grebennikov V. I. , Gerasimov E. G. , Mushnikov N. V. , Kuznetsova T. V.
Published: April 2024

The electronic structure of the rare-earth intermetallic compound La0.73Tb0.27Mn2Si2 has been studied by resonant photoemission spectroscopy using synchrotron radiation, and its formation patterns have been established upon partial replacement of lanthanum atoms by terbium. The dependence of the valence band spectra shape on the photon energy near the absorption edges of the internal levels of manganese, lanthanum, and terbium is analysed. The processes of direct and two-stage production of photoelectrons, elastic and inelastic decay channels of these states with the emission of high-energy electrons due to intra-atomic Coulomb interaction have been studied. The dominant mechanisms of the decay of the excited states of the components under study were determined from the shapes of the spectra. For rare-earth metals elastic decay channel of the excited state is the most probable, while for manganese, it is inelastic, with the formation of a second hole in the valence band with subsequent enhancement of photoemission. Exciting photoemission near M5-absorption edges of rare-earth elements, the main contribution to the valence band comes from terbium 4f-states. Exciting photoemission near L3-absorption edge of manganese, the main contribution to the valence band is made by manganese 3d-states; with an increase in the photon energy in the region after resonance, an Auger channel for the decay of the excited state arises in the form of intensity maximum shift towards the binding energy growth. Features of the topography and magnetic domain structure of the La0.73Tb0.27Mn2Si2 surface were studied by atomic force and magnetic force microscopy at room temperature.
The Prospects of Use of Polarized Neutron Reflectometry to Study Helimagnetism in Rare-Earth Thin Films and Nanostructures on a Compact Neutron Source DARIA
Authors: Devyaterikov D. I. , Kravtsov E. A. , Proglyado V. V. , Zhaketov V. D. , Nikitenko Yu. V. , Khaydukov Yu. N.
Published: April 2024

The results of studying thin films and superlattices of rare-earth helimagnets Dy and Ho by neutron reflectometry are presented. It is shown that neutron reflectometry allows studying magnetic phase transitions in these nanostructures and obtain information about periodicity of magnetic helices in them. It is proposed to create a neutron reflectometer capable of conducting polarization analysis on a compact DARIA neutron source, optimized for studying long-period magnetic orderings in rare-earth helimagnets, and possible directions of this optimization are indicated.
Neutron Source from (γ,n) Reactions at a Laser-Plasma Accelerator and Its Use for Electron Beam Characterization
Authors: Gorlova D. A. , Zavorotny A. Yu. , Tsymbalov I. N. , Ivanov K. A. , Shulyapov S. A. , Volkov R. V. , Savel’ev A. B.
Published: April 2024

Development of compact laboratory-scale neutron sources is of importance both for fundamental physical research and practical applications (for example, neutron radiography and spectroscopy). One of the most promising approaches to the development of such a source is the implementation of laser-plasma accelerated electrons or ions, and the subsequent initiation of nuclear reactions (γ,n), (p,n) or (d,n) with the emission of neutrons. In the present work, a neutron source produced via photodisintegration reactions (γ,n) using an electron beam from a one TW laser-plasma accelerator has been created and characterized. Maximum observed neutron flux was ~105 neutrons/s · srad with a ~106 neutrons per J of laser radiation efficiency. With constant efficiency and 10 times increase in the laser pulse energy the neutron flux will be sufficient for certain applications. Numerical Monte-Carlo simulations of neutron generation by an electron beam with parameters corresponding to those measured experimentally were also carried out. It was demonstrated that the number of generated neutrons can be used to estimate the charge and average energy of accelerated electrons. The obtained values are in good agreement with the values measured by the standard beam diagnostic tools.
Electronic Structure of Tin Dioxide Thin Films
Authors: Manyakin M. D. , Kurganskii S. I.
Published: April 2024

The electronic structure of tin dioxide (001) nanofilms in a wide range of thicknesses has been modeled by the method of linearized coupled plane waves in the framework of the density functional theory in the generalized gradient approximation. The spectra of the total and local partial densities of electronic states characterizing the electronic structure of atoms spread out in various layers of the films under consideration are calculated. It is shown that the influence of the surface leads to the appearance of energy features of the density of states localized in the bang gap. A model describing the layered transformation of the electronic structure during the transition from the surface to the volume of the crystal SnO2 is proposed. A film (001) with a thickness of 8 elementary cells for SnO2 is considered as a model object. It is found that the surface electronic states arising in the band gap in SnO2(001) films are spatially strongly localized – their density drops to almost zero by the third atomic layer from the surface. The applicability of the combined use of the layered superlattice method and the core hole method for modeling X-ray absorption spectra in nanofilms is considered. It is established that when calculating the XANES spectra for atoms in the surface layer of SnO2 nanofilms, the influence exerted by the surface is significantly greater than the influence exerted by the core hole. Therefore, when calculating the XANES spectra for atoms in the surface layer of nanofilms, the core hole can be neglected in the first approximation.
Surface Crystallization and Magnetization Reversal Processes in Amorphous Microwires
Authors: Aksenov O. I. , Fuks A. A. , Abrosimova G. E. , Matveev D. V. , Aronin A. S.
Published: April 2024

The bulk-inhomogeneous crystallization of amorphous microwires of composition Fe73.8Cu1Nb3.1B9.1Si13 has been studied. An assumption was put forward about the influence of the non-uniform distribution of tensile and compressive stresses in the bulk of microwires on their crystallization. It has been established that at the initial stages of crystallization the crystallization occurs in the near-surface region of a microwire with a thickness of about 2.5 μm. It has been established that the sizes of nanocrystals in the surface region of microwire are about 10 nm. It was found that the formation of an amorphous nanocrystalline layer on the microwire surface leads to an increase in the Mr/MS ratio (ratio of remanent magnetization to saturation magnetization), which is associated with a decrease in the magnetic anisotropy due to a decrease in the stress level during heat treatment and nanocrystallization. Chemical etching of annealed microwires leads to a significant increase in the Mr/MS ratio, which is due to an increase in the relative volume of the central domain layer. The results obtained indicate the potential for creating composite amorphous-nanocrystalline structures based on microwires. In the case of microwires of Fe73.8Cu1Nb3.1B9.1Si13 composition, the predominant crystallization of the surface layer can increase the effect of the giant magnetic impedance. Such objects may have potential applications in sensorics, in particular, in magnetic field and strain sensors.
Layered Composite Materials Based on Ti/Ta/Hf/Ceramic to Solve Tasks under Extreme Conditions
Authors: Kamynina O. K. , Vadchenko S. G. , Kovalev I. D. , Prokhorov D. V.
Published: April 2024

Layered composite materials Ti/Ta/Hf/ ceramic were produced via self-propagating high-temperature synthesis (SHS) of pre-structured samples using metal foils (Ti, Hf, Ta, Ni) and reaction tapes (Ti + 0.65C), (Ti + 1.7B) and (5Ti + 3Si). Reaction tapes were prepared by cold rolling from powder mixtures. The microstructure, elemental and phase compositions of the synthesized multilayer composite materials were characterized by Scanning Electron Microscopy (SEM) and X-ray analysis. Their flexural strength was determined according to the scheme of three-point loading at temperatures of 25 and 1100°С. The microstructure analysis of produced materials showed that the joining in the combustion mode of metal foils and reaction tapes is provided due to reaction diffusion, mutual impregnation and chemical reactions occurring in reaction tapes and on the surface of metal foils. The formation of thin intermediate layers in the form of cermets and eutectic solutions provides the synthesized multilayer materials with good strength properties (up to 275 MPa at 25°С, up to 72 MPa at 1100°С). These results are of interest for the development of construction materials operating under extreme conditions.
Detection of Surface-Silvering and Near-Surface Silver Enrichment on AD 253/254 Bosporan Staters by Electron Probe Micro-Analysis
Authors: Abramzon M. G. , Efimova Yu. Yu. , Koptseva N. V. , Gorlenko D. A. , Saprykina I. A. , Smekalova T. N.
Published: April 2024

The article deals with the results of the EPMA investigation of surface of two groups of AD 253/254 Bosporan staters minted in the names of Rhescuporis V and Pharsanzes. It was found that a special silvering technique was used for each group. In the Phescuporis V’s coin production, depletion-silvering was executed by first tempering and oxidizing the flan, then attacking it with organic acids before striking. No silver coating was revealed on his coins. Meanwhile Pharsanzes staters have a silver coating with a thickness of up to 10 µm. The elements chlorine, calcium, sodium and magnesium that were first revealed in the surface layer suggest the use of a special paste for silvering the coins of this king. Its components could be chlorides of silver, sodium, ammonium, mercury, potassium hydrogen tartrate and chalk as a thickener. Both techniques for silver surface enrichment of coins were common practice in the Roman coinage from the late third to beginning of the fourth century AD.
Synthesis and Structure of the Nanosized Cobalt Coatings on Porous Aluminum Oxide
Authors: Valeev R. G. , Alalykin A. S. , Beltiukov A. N. , Kriventsov V. V.
Published: April 2024

The results of studies of the morphology and chemical structure of cobalt coatings deposited by magnetron sputtering on nanostructured surfaces of porous alumina with different morphologies are presented. The morphology of porous alumina was specified by the anodization voltage in solutions of sulfuric (25 V) and oxalic (40 and 120 V) acids. Using scanning electron and atomic force microscopy, it has been shown that the coatings have morphological features, which are hexagonally arranged nanoparticles formed at the boundaries between pores. With an increase in the size of nanopores on the surface of the substrates, the size and shape of the morphological features of the deposited coatings change. According to X-ray absorption fine structure spectroscopy and fine structure spectroscopy of the near region of the X-ray absorption edge, there are changes in the local atomic structure of cobalt, in particular, cobalt in a coating sample deposited on the surface of porous alumina obtained by anodizing at a voltage of 25 V in sulfuric acid, oxidized more strongly, which is associated with greater chemical activity due to the smaller sizes of the nanoparticles that make up the coating. The results obtained will allow in the future to make a directed change in the formation of structure-sensitive properties, such as chemical and electrochemical activity, magnetic sensitivity, of the resulting coatings.
Microstrip Silicon Detector for Study of Ultra-Fast Processes at the Synchrotron Radiation Beam
Authors: Aulchenko V. M. , Glushak A. A. , Zhulanov V. V. , Zhuravlev A. N. , Kiselev V. A. , Kudryavtsev V. N. , Piminov P. A. , Titov V. M. , Shekhtman L. I.
Published: April 2024

Present status of the development of the prototype of the Detector for imaging of explosions (DIMEX) based on silicon microtrip sensor is discussed. The prototype includes silicon p-in-n sensor with metal strips in direct contact with p-implants. Strips are 30 mm long and have 50 um pitch. Signals from the strips are read out with specially developed ASICs DMXS6A, that include 6 channels with DC compensation circuit at the input, four integrators, 32 analogue memory cells and output analogue shift register. The prototype detector has 96 registration channels provided with 16 DMXS6A ASICs. Each strip of the sensor is connected to the guard-ring through a 400 Ohm resistor and through 100 kOhm resistor to the input of the front-end ASIC. This resistive divider allows to adapt the dynamic range of the integrator of the ASIC to the full flux range of the beam line 8 at the VEPP-4M storage ring that includes 9-pole wiggler with 1.9 T B-field as SR source. The measurements of the dynamic range of the DIMEX-Si prototype demonstrate that maximum photon flux from one bunch that can be measured by this detector exceeds 100 000 photons per channel. For these measurements the sensor was inclined at an angle of 1.7 degrees with respect to the beam plane in order to increase quantum efficiency. The possibility to work in multi-bunch mode with bunches following in 55 ns is demonstrated, that proves that this detector can be successfully exploited at new SR-source SKIF that is under construction in Novosibirsk region.
Measurements of Thermophysical Characteristics of Thin Film Metal Filters for Extreme Ultraviolet Radiation
Authors: Lopatin A. Ya. , Luchin V. I. , Salashchenko N. N. , Tsybin N. N. , Chkhalo N. I.
Published: April 2024

Knowledge of the emissivity and thermal conductivity of thin metal films used in conjunction with multilayer mirrors for spectral selection of radiation in the extreme ultraviolet and soft X-ray wavelength ranges is necessary in order to correctly calculate the heating of film elements at high heat loads. Heating is associated with the absorption in the film of a significant fraction of the incident intensity, and the concept of a high heat load is somewhat arbitrary, since even at an absorbed intensity level of the order of 1 W/cm2 a freestanding film can be heated in vacuum by several hundred degrees. In the first approximation, to estimate the thermal conductivity coefficient, one could use tabular values for massive samples of the corresponding metals or use the well-known Wiedemann–Franz law which links the thermal conductivity and the electrical resistivity of the sample – the latter is easier to be measured. However, an analysis of the literature data indicates significant errors that are possible when using any of these approaches. Therefore, in this work, we have measured the thermal conductivity directly by processing the temperature distribution obtained by IR pyrometry over a film sample mounted on a heated frame or heated by a flowing electric current. Thermophysical characteristics (thermal conductivity and emissivity) were determined for samples of film absorption filters based on Mo, Al, and Be of submicron thickness (from 100 nm), as well as for films of copper – a metal whose bulk samples have high thermal and electrical conductivity. As expected, significant differences were found between the thermal and electrical properties of the film materials and the properties of the same metals in monolithic samples.