bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self-sustained Oscillations and Limit Cycles in Rayleigh System with Cubic Return Force
Authors: Kumakshev S. A. 
Published: April 2024

An oscillatory system with an excitation mechanism as in a Rayleigh oscillator, but with a nonlinear (cubic) returning force, is investigated. Using the accelerated convergence method and the continuation procedure for the parameter, limit cycles are constructed and the amplitudes and periods of self-oscillations are calculated. This is done for a wide range of feedback coefficient values, in which this coefficient is not asymptotically small or large. The proposed iterative procedure allows to achieve the specified accuracy of calculations. The analysis of the features of the limit cycle caused by an increase in the self-excitation coefficient is carried out. The results obtained are compared with the self-oscillations of a classical Rayleigh oscillator with a linear returning force.
LOW-TEMPERATURE ELECTROLYTIC PRODUCTION OF Al-REM ALLOYS IN CRYOLITE MELTS
Authors: Rudenko A. V. , Tkacheva O. Yu. , Kataev A. A. 
Published: April 2024

The process of electrolytic production of Al–Y and Al–Sc alloys in an electrolyte based on potassium cryolite KF–NaF(10 wt %)–AlF3 with a cryolite ratio (CR) of 1.5, containing Al2O3, Sc2O3, or Y2O3 oxides, in a cell with vertical electrodes has been studied. The Fe–Ni–Cu alloy served as an inert anode. The wetted cathode was a graphite plate coated with the aluminum diboride. The electrolysis was carried out at a cathode current density of 0.2 A/cm2 and a temperature of 830°C. The Al2O3 mass was calculated based on the value of the current efficiency of 60%. The Sc2O3 additive was introduced into the melt in an amount of 1 wt %. The mass of the Y2O3 additive was chosen based on its solubility in the melt under study. For this, the influence of Y2O3 additives on the liquidus temperature of the quasi-binary mixture [KF–NaF(10 wt %)–AlF3 (KO = 1.5)]–Y2O3 was determined and it was found that, in contrast to Sc2O3 additives, which lower the liquidus temperature of the cryolite melt, small additions of Y2O3 lead to its sharp increase. It has been found that the efficiency of the electrolytic reduction of Y2O3 is 10 times higher than that of the aluminothermic reduction. Other things being equal, the efficiency of the electrolytic reduction of Y2O3 is higher than that of Sc2O3. Alloys Al–Y and Al–Sc with a REM content of 0.6 wt % have been obtained. However, the time to reach the maximum recovery of yttrium significantly exceeds the time to recover scandium. Metallographic studies of the obtained alloys indicated the presence of Al3Sc and Al2Y intermetallic compounds. A conclusion is made about the fundamental possibility of low-temperature electrolytic production of Al-REM alloys in cryolite melts based on potassium cryolite in vertical cells with an inert metal anode and a wettable cathode.
Decolorization of Dyes in the Bioelectrochemical System Depending on the Immobilization of <i>Shewanella oneidensis</i> MR-1 Cells on the Anode Surface and Electrical Stimulation of the External Circuit
Authors: Samkov A. A. , Chugunova Yu. A. , Kruglova M. N. , Moiseeva E. V. , Volchenko N. N. , Khudokormov A. A. , Samkova S. M. , Karaseva E. V. 
Published: April 2024

The effect of the polarity of the electrical stimulation of the external circuit of the bioelectrochemical systems, as well as the immobilization of Shewanella oneidensis MR-1 cells containing the DyP peroxidase gene on the rate of discoloration of dyes of different types was found. For the crystal violet triphenylmethane dye, the maximum decolorization rate by suspended S. oneidensis MR-1 cells 2.05 ± 0.07 μM/h was noted in the case of connecting a 1.2 V direct polarity DC voltage source. One of the minimum rates was observed in the case of reverse polarity of the connection. In the case of cells immobilized on the anode, the rate was higher, reaching 2.91 ± 0.09 μM/h and did not decrease with increasing substrate concentration. The lowest values were also noted for the reverse connection of the voltage source. In case of the azo dye congo red, the maximum rate was found for a source with direct connection and an open circuit (0.26 ± 0.01 and 0.29 ± ± 0.02 μM/h, respectively), the minimum value is 0.11 ± 0.02 μM/h for reverse connection. For the crystal violet decolorization products, a significant decrease in the intensity of the main absorption peak at 590 nm band was found, with no notable hypsochromic shift. The qualitative changes in the decolorization products composition are indicated by the appearance, in case of a direct polarity of the ionistor connection, of a new absorption maximum in the region of 360 nm. The results may be of interest for the development of new methods of bioelectrochemical cleaning.
Comparison of Biochemical Properties of Recombinant Alpaca (<i>Vicugna pacos</i>) Chymosins Produced in Pro- and Eukaryotic Expression Systems
Authors: Belenkaya S. V. , Elchaninov V. V. , Chirkova V. Y. , Shcherbakov D. N. 
Published: April 2024

Based on the yeast Kluyveromyces lactis, a strain-producer of recombinant alpaca prochymosin (Vicugna pacos) was developed. A comparative analysis of the biochemical properties of recombinant alpaca chymosin obtained in the expression systems of K. lactis and Escherichia coli was carried out. It was found that the recombinant alpaca chymosin synthesized in K. lactis exceeds the analog obtained in E. coli by 12.9 times in the number of enzyme turnovers, and by 2.9 times in catalytic efficiency. Compared to chymosin expressed in E. coli, the enzyme obtained in a eukaryotic producer has a thermal stability threshold increased by 5°C. Replacing a prokaryotic producer with a eukaryotic one enhances the negative sensitivity of the milk-clotting activity of recombinant alpaca chymosin to an increase in substrate pH in the range of 6.1–6.9, which is accompanied by an increase in the duration of coagulation by 8–35%. With an increase in the concentration of CaCl2 in the substrate, the coagulation activity of the target enzyme synthesized in E. coli was 12–14% higher than that of its analogue obtained in K. lactis.
Fatty Acid Profiles Change and the Volatile Organic Compounds Formation During the Cow’S Milk Fermentation with Probiotic <i>Lacticaseibacillus paracasei</i> Strains
Authors: Moiseenko K. V. , Shabaev A. V. , Glazunova O. A. , Savinova O. S. , Fedorova T. V. 
Published: April 2024

In this work, a comparative analysis of the profile of fatty acids (FA) and volatile organic compounds (VOCs) for skimmed cow’s milk fermented by four different probiotic strains of Lacticasibacillus paracasei (ABK, KF1, MA2 and MA3) was carried out. Analysis of FA and VOC profiles was performed using gas chromatography with mass spectrometric detection (GC-MS). For additional visualization of odor changes and its intensity in the fermented milk samples, the E-nose “electronic nose” odor analyzer was used. In total, presence of 42 different FA was detected in all samples, of which 17 were saturated, 8 monounsaturated, and 5 polyunsaturated. The strain-specific differences between the studied samples were of a complex nature and could not be explained only by the variation in the contribution of several individual FAs. The FA-nutritional indices, characterizing the nutritional and biological value of the samples, were different for milk fermented by different strains. Analysis of VOCs showed that the main odor-forming compounds in the studied samples were FAs and their reaction products, 2-heptanone, 2-nonanone, and 2-nonanol, formed as a result of the following chain of transformations: β-oxidation → decarboxylation → reduction. The aroma of L. paracasei fermentation products, predicted on the basis of the odors of individual VOCs, generally coincided with their organoleptic assessment – a flavor typical of fermented milk (yogurt, curdled milk) with floral and fruity notes.
Military Doctors are Members of the Scientific Council of the Russian Academy of Sciences for Radiobiology
Authors: Grebenyuk A. N. 
Published: April 2024

From the moment of its creation in 1962 to the present, the Scientific Council of the Russian Academy of Sciences for Radiobiology (originally the Scientific Council at the USSR Academy of Sciences on the complex problem “Radiobiology”) has paid great attention to the damaging effects of radiation and medical radiation protection. Already the first composition of the Council included scientists who received significant experience in the field of radiobiology during active military service in educational, scientific and clinical institutions of the USSR Ministry of Defense – T.K. Dzharakyan, P.G. Zherebchenko, G.A. Zedgenidze, A.S. Mozzhukhin, V.P. Paribok. The first chairman of the Bureau of the Council was the outstanding Soviet radiobiologist A.V. Lebedinsky, who previously led radiobiological research at the Kirov Military Medical Academy. Over the years, the Council included current and retired military doctors – I.G. Akoev, E.A. Zherbin, V.I. Legeza, A.N. Grebenyuk. The Deputy Chairman of the Council, President of the Radiobiological Society of the Russian Academy of Sciences is currently I.B. Ushakov, who for a long time headed scientific institutions specialized for military radiobiology – the State Research Test Institute of Aviation and Space Medicine of the Ministry of Defense of the Russian Federation and the State Research Test Institute of Mi-litary Medicine of the Ministry of Defense of the Russian Federation. Throughout the existence of the Council, military doctors took an active part in its work, formed and supervised relevant research in the field of military radiobiology and medical radiation protection.
The Snow Depth in Forests and Fields on Lowlands of Russia under the Current Climate Conditions
Authors: Sosnovsky A. V. , Osokin N. I. 
Published: April 2024

Received August 11, 2023; revised August 27, 2023; accepted October 2, 2023Average values of maximum snow depths (MaxSD) estimated separately under conditions of forests and fields on lowlands of Russia were compared during the past 29 years. It was found that MaxSD in the fields for the current climatic period 1991–2020 increased by 5% compared to the period 1966–1990 and decreased by 8% in the forests. For the periods 1966–1990, 1981–2010, and 1991–2020, the ratio of MaxSD in a forest to similar one in a field (which we refer to as the snow survey coefficient) has been constantly decreasing. The snow survey coefficients for these periods were equal to 1.24; 1.12 and 1.08, respectively. In 1991–2020, the greatest values of this ratio were obtained in the northeast of the European part of the territory of Russia (ETR) and in the south of Western Siberia, where the maximum thickness of snow cover in the forest was found to be significantly higher than in the field. The lowest values were observed in some areas of the ETR center as well as in south-east and south-west, and in the south of Eastern Siberia. Here, for the periods 2001–2010 and 2011–2020, the values of the snow survey coefficients were estimated as 1.07 and 1.03 respectively. The coefficient for 1991–2020 decreased, on average, by 12% compared to 1966–1990. The maximum decrease in this ratio – by 15–25% – occurred in the south-west of Eastern Siberia and in a larger part of the ETR in the south. In 2011–2020, the MaxSD values increased in forests in the south-east of the ETR by 5–15%, and decreased in the south-west and the west of the ETR by 15–25% compared to 1966–1990. At the same time in fields, the MaxSD increased by 15–30% in the east of the ETR and the south of Siberia and decreased in the center and south-west of the ETR by 10–15%. The average value of the MaxSD in the field for the period 2011–2020 increased by 6% compared to 1966–1990 and decreased in the forest by 10%. Relative to other periods, the greatest increase in MaxSD was observed in 2001–2010. In the period 2011–2020, the MaxSD both in the forest and in the field mainly decreased relative to the period 2001–2010. In the current climatic period (1991–2020), the tendency for equalization of the MaxSD in forests and fields has been confirmed.
THE METHOD FOR CO-REGISTRATION OF DIGITAL TERRAIN DATA TO OBTAIN HYDROLOGICALLY CORRECT MODEL OF THE EARTH’S SURFACE<a href="#FN1"><sup>1</sup></a>
Authors: Kharchenko S. V. 
Published: April 2024

There are problems with the co-registration of digital terrain models which were created by drones to obtain useful data for a numerical hydrological or erosional modeling. The different surveys can be produced at different time of a day, in various seasons or even years, making it difficult spatially reference the data. Many co-registration algorithms usually perform the statistical fitting of point clouds or raster models. Such approach violates the hydrological correctness of the final data, it makes artifacts appearing, such as various escarps and visible joints. The search for the contour of “zero error” on the raster of elevations difference is the bases of presented algorithm. This contour is used for the stitching of original elevation models together. As criteria for the quality assessment of the final elevation models are used: 1) the statistical distributions of slope gradient, i.e. parameter that affects the results of modeling the water and sediment flows, slope stability, etc., 2) the constancy of the microcatchments geometric structure. The algorithm was tested on three sites located in plain, low-mountain and mid-mountain zones. In all examples, the high efficiency of the method was shown. At the same time, the technique was constructed for keeping the significant features of terrain morphology in data. The average slope does not deviate by more than 1° in comparison with the original data. The Spearman rank correlation of the slope varies in different cases at 0.9–0.99 (with an average value of 0.96). The coefficients of geometric similarity of microcatchment patterns on the final models in all cases show even larger values (1.09) than on the original data without any correction (0.98) in the areas their overlap.
SPECTRAL ANALYSIS OF LAND SURFACE WITH THE CONSTRUCTION OF A NEURAL NETWORK FOR GEMS SEARCH ON THE EXAMPLE OF THE LUK TIEN MOUNTAIN RANGE (NORTHERN VIETNAM)<a href="#FN1"><sup>1</sup></a>
Authors: Sergeev I. S. , Kuksa K. A. , Glebova A. B. 
Published: April 2024

The study area is located in the north of Vietnam in the province of Yen Bai and it is a large (14.5 × 6.5 × × 0.8 km) structural and denudational butte on the periphery of high-dissected low mountains Con Voi, and they are also slopes and bottoms of the neighbor rivers valleys. There are a lot of gemstone outcrops on the territory related with the vein formations in the strata of marbles. The area is relatively difficult to access for geological fieldworks. Therefore, in order to organize and conduct field geological prospecting work, the task was to obtain preliminary data on the possible localization of useful mineralization areas based on the analysis of available geological and geomorphological information. For the task, the spectral regularities of the land surface dissection spatially associated with veined geological formations in the near-surface part of the marble strata were studied, we used the discrete Fourier transform for this. The binary classification (for classes of potentially useful and useless areas) of the elevation amplitudes according with different spatial frequency of topographic dissection was provided with the simple neural network – two-layer perceptron. This algorithm is implemented on the basis of the scientific analysis libraries of the Python. The application of this technique made it possible to carry out a prediction for ruby-spinel mineralization in bedrock over a study area of more than 200 km2. Fieldworks in 2019 verified the predicted data by the ways of mineralogical and geochemical testing of the accessible part of the predicted points. An average estimate of the predictive strength of the method used was obtained as 35% – every third site predicted by the neural network actually contains the primary sources of rubies and spinels in the territory under consideration.
VEGETATION AND CLIMATE CHANGES IN THE SOUTHERN URALS IN THE LATE GLACIAL AND HOLOCENE DERIVED FROM POLLEN RECORD OF LAKE BOLSHOE MIASSOVO<a href="#FN1"><sup>1</sup></a>
Authors: Nigamatzyanova G. R. , Frolova L. A. , Nigmatullin N. M. , Yusupova A. R. , Nurgaliev D. K. 
Published: April 2024

A spore-pollen analysis of a 526 cm sediment core retrieved from Lake Bolshoe Miassovo, Southern Urals, was carried out. The obtained data made it possible to reconstruct the vegetation cover in the lake’s catchment area and the climatic situation of the region for 13 400 cal yr BP, which significantly expands and complements the paleogeographic chronicle of the Southern Urals. It was found that in the range of 13 400–12 700 cal yr BP in the conditions of a relatively warm and dry climate of Allerød, periglacial forest-steppe formations were widespread in the studied region. Steppe herb communities and birch-pine sparse woodlands with spruce grew on open landscapes. The pine degradation and replacement of spruce with more cold-resistant larch was most likely caused by a cooling in the period of 12 700–11 700 cal yr BP, which corresponds to the Younger Dryas. The periglacial forest-steppe formations are replaced by birch forests since 11 700 cal yr BP. The significant changes in the vegetation cover of the lake’s catchment area indicate warming and humidification of the climate at the beginning of the Holocene. The dominance of birch forests in the interval of 11 300–10 300 cal yr BP, probably, corresponds to the second half of the Pre-Boreal period. The distribution of pine and spruce in the range of 10 300–8300 cal yr BP indicates a warming of climatic conditions in the Boreal period. Since 8400 cal yr BP the proportion of broad-leaved species in the tree stand increases. The broad-leaved species cover reached its peak between 6000–4500 cal yr BP at the end of the Atlantic - the beginning of the Sub-Boreal period (Holocene climatic optimum). Some cooling of the climate was observed in the range of 4500–2000 cal yr BP, which presumably corresponds to the Sub-Boreal and the beginning of the Sub-Atlantic period. The birch forest with spruce and broad-leaved species grew in the lake’s catchment area. Some aridization and warming of the climate in the Sub-Atlantic period in the range of 1800–1000 cal. yr BP led to an increase in the role of pine and a reduction of spruce in the area around the lake. Since 1800 cal yr BP the vegetation of the territory adjacent to Lake Bolshoe Miassovo was similar to the modern one: pine-birch forests with an admixture of dark coniferous and broad-leaved species prevailed on the territory.
RELATIVE SEA-LEVEL CHANGE OF THE WHITE SEA IN THE LATE GLACIAL AND HOLOCENE: CASE STUDY OF THE SREDNYAYA TRET’ LAKE, EASTERN COAST OF THE GORLO STRAIT<a href="#FN4"><sup>4</sup></a>
Authors: Repkina T. Yu. , Kublitskiy Yu. A. , Leontiev P. A. , Gurinov A. L. , Vakhrameeva E. A. , Losyuk G. N. , Shilova O. S. , Lugovoy N. N. 
Published: April 2024

The relative sea-level changes for the time interval of ~12.1–9.1 ka cal BP were reconstructed on the eastern coast of the Gorlo Strait using the results of paleolimnological, GPR and geomorphological analyses conducted in the basin of the Srednyaya Tret’ Lake (7.3 m a.s.l., 66.014009° N, 41.086294° E), as well as UAV surveying of the lake surroundings. Bottom sediments of the lake were studied from the four core sections and correlated with each other according to the results of GPR data interpretation. Lithostratigraphic descriptions of bottom sediment cores, grain-size and diatom analyses, radiocarbon dating (AMS), determination of LOI, Corg content and Corg /Norg ratio were performed. We present the reconstruction of the coastlines at heights of 4–5 and 12–15 m formed by currents and/or wave processes within the lower Ruch’i River valley and Srednyaya Tret’ Lake according to field observations and interpretation of space images. As a result, the position of the relative sea-level and the chronology of the Late Glacial (Younger Dryas) transgression and the early stages of the Holocene (Tapes) transgression were refined. Late glacial transgression finished earlier than ~12.1 ka cal BP, and its relative level was probably no higher than 15 m a.s.l. After a deep regression, the relative sea-level approached the modern again ~9.5 ka cal BP, and at the Tapes transgression maximum (~9.1 ka cal BP) it was near the lake runoff threshold (∼5 m). Though the coastline was near the lake basin, sea waters never entered the lake. Sands, carried by the wind, accumulated in the part of the basin facing the coast. The the Srednyaya Tret’ Lake basin was gradually filled by fresh water according to the results of diatom analysis.
LATE GLACIAL AND HOLOCENE HISTORY OF LAKE BOLSHOE MIASSOVO (SOUTHERN URALS) BASED ON DIATOM ANALYSIS OF BOTTOM SEDIMENTS<a href="#FN1"><sup>1</sup></a>
Authors: Valieva E. A. , Frolova L. A. , Palagushkina O. V. , Nigmatullin N. M. , Nigamatzyanova G. R. , Nurgaliev D. K. 
Published: April 2024

Bottom sediments are the most important “archive” containing information about the development of lake ecosystems. One of the most reliable and widely used methods of studying bottom sediments is diatom analysis (Juze et al., 1949). Currently, it is part of a group of guiding methods used to reconstruct the historical dynamics of the environment and climate (Rudaya et.al., 2012; Palagushkina et.al., 2018). In this work, the history of development of Lake Bolshoe Miassovo (Southern Urals) reconstructed using the taxonomic composition of diatoms found in the 526 cm long sediment core is presented. The maximum age of the sediments in the column was 13 500 years BP. According to the results of the study, 123 taxa of diatoms belonging to 47 genera were identified in the lake sediments. Diatom analysis of the bottom sediments of the studied lake allowed us to identify the main stages of the evolution of the reservoir during the Late Glacial and Holocene. During ~13 200–11 700 yr BP, in the period of a cool climate, the lake was a deep body of water with a constant water level and an extensive zone of shallow waters overgrown with macrophytes; then ~11 700–8500 cal. years BP against the background of cooling, the water level decreased; from ~8500–4600 cal. years BP was the stage of increasing water level in the lake in a warmer and wetter climate; in the period ~4600–2500 cal. years BP there was an increase in productivity of algal communities; during ~2500–800 cal. years BP against the background of decreasing temperature, a deep lake with low mineralized water, and presence of swampy shallow waters with acidification processes in them is finally formed.