bluuebunny/crossref_metadata_2025 huggingface dataset:
Digital PCR as a Highly Sensitive Diagnostic Tool: a Review
Authors: Kopylova K. V. , Kasparov Ed. W. , Marchenko I. V. , Smolnikova M. V.
Published: April 2024

Nowadays digital PCR (dPCR) is a nucleic acid quantification method widely used in genetic analysis. One of the most significant advantages of dPCR over other methods is the possibility for absolute quantitative determination of genetic material without construction of calibration curves, which allows one to detect even single molecules of nucleic acids, and, hence, early diagnosis of diseases. A specific characteristic of dPCR is the detection of the analyzed biological object in each microreaction, followed by the presentation of the analysis results in a binary system, thereby giving the method name. The key aspects of developing the dPCR method, i.e. from the first devices based on microfluidic chip technology to modern systems capable of measuring a target at a concentration of up to 1 in 100 000 copies were shown in the current work. We analyzed the data on the detection of various pathogens using dPCR, as well as summarized various study results demonstrating the innovativeness of this method “point-of-care”. Both the possibilities of multiplex dPCR analysis and its potential in clinical practice were presented. The review also addresses the issue of the dPCR role in the development of non-invasive methods for oncological diseases to be analyzed. Possible ways of developing dPCR technology were emphasized, including the use as a “point-of-care” systems.
Analysis of the Tomato Aspermy Virus Complete Genomes Suggests Reassortment in Russian Isolates from Chrysanthemum
Authors: Sheveleva А. А. , Krasnov G. S. , Kudravtseva А. V. , Snezhkina А. V. , Bulavkina E. V. , Chirkov S. N.
Published: April 2024

Tomato aspermy virus (TAV, genus Cucumovirus from the family Bromoviridae) is one of the most common and harmful chrysanthemum viruses, causing severe flower distortion, size reduction and color breaking. Metatranscriptome sequencing of chrysanthemum plants of the Ribonette and Golden Standard cultivars from the collection of the Nikita Botanical Garden (Yalta, Republic of Crimea) generated TAV-related reads. The complete genomes of two Russian isolates of the virus were assembled from the reads obtained. This is the first report of full-length TAV genomes from Russia. Typically of cucumoviruses, the segmented TAV genome is represented by three single-stranded positive-sense linear RNA molecules with a length of 3412 (RNA1), 3097 (RNA2) and 2219 (RNA3) nucleotides. Five open reading frames (ORF) have been identified that encode replicase (ORF1), RNA-dependent RNA polymerase (ORF2a), silencing suppressor protein (OFR2b), movement protein (OFR3a) and the virus coat protein (ORF3b). The identity of the TAV genomes from the two chrysanthemum cultivars was 99.8% for all three viral RNAs, and with other TAV isolates from Genbank – 97.5–99.7 (RNA1), 93.8–99.8 (RNA2), and 89.3–99.3% (RNA3). Phylogenetic analysis showed that RNA1 and RNA3 of the Russian isolates were assigned to heterogeneous groups of TAV isolates found on various plant species in different regions of the world. At the same time, RNA2 clearly clustered with tomato isolates SKO20ST2 from Slovenia and PV-0220 from Bulgaria and, to a lesser extent, with the Iranian isolate Ker.Mah.P from petunia and the Chinese isolate Henan from chrysanthemum. The incongruence of phylogenetic trees reconstructed from different segments of the viral genome suggests pseudo-recombination (reassortment) in the Russian TAV isolates.
Effects of Hydrogen Sulfide Donor GYY4137 on the Proteasome Pool of Colon Cancer Cells
Authors: Grigorieva E. V. , Astakhova T. M. , Burov A. V. , Karpov V. L. , Morozov A. V.
Published: April 2024

Cancer cells are characterized by an increased level of metabolism and are highly dependent on the correct functioning of the processes that ensure homeostasis. Reactive sulfur species (RSS) are important molecular modulators of metabolic processes in both healthy and tumor cells. The effect of RSS and, in particular, H2S, on key cellular systems, including the ubiquitin-proteasome system (UPS), which ensures the destruction of most intracellular proteins, has been shown. The main components of the UPS are proteasomes ‒ multisubunit protein complexes, within which protein proteolysis occurs. At the same time, data on the effect of H2S directly on the pool of proteasomes in tumor cells are insufficient. Here, we studied the effect of incubation of SW620B8-mCherry colon adenocarcinoma cells expressing a fluorescently labeled proteasome subunit with 50, 100, and 200 µM of hydrogen sulfide donor GYY4137. The effect of the substance on the proteasome pool was assessed 6, 24, 48, and 72 h after administration. It was shown that the chymotrypsin-like and caspase-like proteasome activity decreases in cells incubated with 200 µM of the GYY4137 for 24 h. This coincided with an increase in the expression of proteasome subunit genes. In lysates of cells incubated with 200 µM GYY4137 for 48 h an increase in the content of the constitutive β5 subunit was observed. Against this background, the activity of proteasomes in cells levels off. Following prolonged incubation with GYY4137 (72h), an increase in the expression levels of some proteasome genes was also observed, though this did not have a significant effect on the activity and subunit composition of proteasomes. Thus, the data obtained indicate the modulation of proteasome activity by the hydrogen sulfide donor, as well as the effect of GYY4137 on the levels of transcription and translation of proteasome genes.
Characteristics of δ-Aminolevulenic Acid Dehydratase of the Cold-Water Sponge Halisarca dujardinii
Authors: Kravchuk O. I. , Shagimardanova E. I. , Mikhailov V. S. , Zhurakovskaya A. I. , Gornostaev N. G. , Adameyko K. I. , Ziganshin R. H. , Mikhailov K. V. , Finoshin A. D. , Lyupina Yu. V.
Published: April 2024

Delta-aminolevulinic acid dehydratase (ALAD) is a key enzyme in the cytoplasmic pathway of heme biosynthesis. Here, a primary structure of the ALAD gene of the marine cold-water sponge Halisarca dujardinii, a multimeric structure of the ALAD/hemB protein, and the ALAD gene expression during the sponge annual reproductive cycle were analyzed. On the base of results obtained one can suppose that the sponge ALAD gene expression is regulated by the transcription factor GATA-1 and DNA methylation. Re-aggregation of the sponge cells was accompanied by a decrease in ALAD expression and a change in the cellular content of the active ALAD/hemB form. Further study of heme biosynthesis and the role of ALAD/hemB in morphogenesis of basal animals may provide new opportunities for correcting pathologies in higher animals.
Identification of the 67-kDa Melittin-Like Proteins Interacting with Na+/K+-ATPase
Authors: Varfolomeeva L. A. , Klimanova E. A. , Sidorenko S. V. , Fedorov D. A. , Lopina O. D.
Published: April 2024

Melittin, a peptide from bee venom, was found to interact with many proteins, including calmodulin target proteins and ion-transporting P-type ATPases. It is assumed that melittin mimics a protein module involved in protein-protein interactions within cells. Previously, a Na+/K+-ATPase containing the α1 isoform of the catalytic subunit was found to co-precipitate with a protein with a molecular weight of about 70 kDa that interacts with antibodies against melittin by cross immunoprecipitation. In the presence of a specific Na+/K+-ATPase inhibitor (ouabain), the amount of protein with a molecular weight of 70 kDa was increased in the precipitate. In order to identify melittin-like protein from murine kidney homogenate, a fraction of proteins (with a molecular mass of approximately 70 kDa) was obtained using affinity chromatography with immobilized antibodies specific to melittin. By mass spectrometry analysis, the obtained protein fraction was found to contain three molecular chaperones of Hsp70 superfamily: mtHsp70 (mortalin), Hsp73 and Grp78. These data suggest that chaperones from the Hsp70 superfamily contain a melittin-like module.
Effect of Rock on Aquathermolysis Reactions at Laboratory Scale (A Review)
Authors: Luis Miguel Salas-Chia , Paola Andrea Le�n Naranjo , Adan Yovani Le�n Berm�de
Published: April 2024

Enhanced recovery methods are an important stage in the oilfield development and exploitation program. They allow generating an increase in production related to the decrease of the remaining oil in the reservoir, which was not possible to remove in previous production schemes. Among them, steam injection is one of the methods used, whose main objective is to reduce the viscosity of the crude oil. In the literature there are researches where is evident an interaction between the steam and the crude oil in the reservoir, giving way to the occurrence of chemical reactions called Aquathermolysis. This transformation is a chemical result that occurs at temperatures between 200 to 325°C typical for steam injection. However, the investigations have been focused more on the fluid-fluid interaction than the rock-fluid synergy. The present work aims to better understand the synergy generated in the fluid-rock interaction through a systematic review of the research found in the literature associated with the use of rock fragments, minerals, or porous media in steam injection conditions. For analyzing the data, a descriptive bibliometric study was made with the selected studies where a rock sample was used. As a result, the addition of the mineral and rocks over the reactions generates a catalytic effect observed in the physical and chemical crude oil properties changes. This additional effect is generated for the presence of some minerals in the rock sample and this behavior could change according to its composition. Also, the gas production and its variation under different operational parameters are evidence of rock presence benefits over the process.
Research on Nano Inhibition and Plugging Potassium Amine Polysulfonate Drilling Fluid System to Prevent Wellbore Instability in Deep Complex Formations
Authors: Shuo Yang , Song Deng , Yixin Zhang Xiaopeng Yan , Hongda Hao , Caibao Wang , Lei Wang
Published: April 2024

The wellbore instability caused by complex strata is a common problem in drilling engineering, which not only causes economic losses, but also reduces the field drilling efficiency. This paper has taken Block A of Junggar Basin as an example to explore the causes of wellbore instability in complex strata and establish corresponding solutions. Studying the core samples in this area and analyzing the logging data, it is concluded that the micro-fractures developed in the rock layer of the block provide natural channels for the entry of filtrate. At the same time, the water-sensitive clay minerals in the formation have hydration after encountering the filtrate. By optimizing the composition, the corresponding nano-strong inhibition and strong plugging potassium amine polysulfonate drilling fluid system (NPAP-2) was established. The overall use of asphalt anti-sloughing agent, nano-and micro-scale cracks (gaps) for physical plugging, wetting inversion control surface water absorption, chemical inhibition of internal hydration. The performance test shows that the HTHP water loss of the drilling fluid system is less than 10 mL, the recovery rate of rock sample is more than 86%, the viscosity is reasonable, the expansion rate is more than 89%, and the filtration loss is reduced from 8.0 to 5.0 mL. The results show that the NPAP-2 can reduce the liquid activity to enhance the inhibition, effectively improve the settlement stability of drilling fluid, reduce the filtration and ensure the wellbore stability.
Dehydrogenation of Ethylbenzene to Styrene over Rhenium- and Tungsten-Containing Porous Ceramic Converters
Authors: Fedotov A. S. , Grachev D. Yu. , Bagdatov R. A. , Tsodikov M. V. , Uvarov V. I. , Kapustin R. D. , Pol' S. , Dyumen'il' F.
Published: April 2024

A series of tubular porous ceramic converters modified with mono- and bimetallic catalytic systems based on rhenium and tungsten were prepared by a combination of self-propagating high-temperature synthesis and the sol–gel method. These converters were tested in dehydrogenation of ethylbenzene to styrene. Among the tested samples, a monometallic tungsten-containing converter exhibited the optimal properties as it achieved the highest target product production performance. Within the temperature range of 550–600°C, this converter provided a yield of styrene up to about 15 wt % and styrene productivity up to about 22 g h–1 dm–3, with the carbonization of the sample not exceeding 5 wt % over about 6 h of reaction.
Increasing the Efficiency of Demulsification Treatment in Petroleum Industry Using a Multicomponent Demulsifier Package
Authors: Azizollah Khormali
Published: April 2024

In this work, a multicomponent demulsifier package (named BDTXI) was developed for increasing the demulsification performance of the water-in-oil emulsions. Optimized demulsifier formulation consists of three active components (1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide, dodecyltriemthylammonium chloride, trioctylmethylammonium chloride), xylene, and isopropanol. A positive synergistic effect was observed among the active components of BDTXI. The concentrations of the components of the developed demulsifier package are determined based on obtaining the best synergistic effect. The demulsification efficiency of BDTXI was higher than commercial reagents at any concentration, water content, and temperature. The optimal concentration of BDTXI was 50 ppm, at which its demulsification effectiveness was more than 97%. The developed demulsifier package could adsorb at the oil-water interface, promote the colloidal dissolution of the emulsion layers, and form a hydrophilic surface characterized by a weak structural strength. The demulsification mechanism of BDTXI was based on minimizing the interfacial tension in order to be able to break the film and increase the frequency of droplet collisions. The change in the temperature and water content of the emulsions did not affect the demulsification performance of BDTXI. Moreover, the average reduction in the asphaltene flocculation parameter with the use of BDTXI and commercial reagents was about 19 and 11%. The results of the analysis of the backscattering light intensity, turbiscan stability index, zeta potential, and shear rate of the emulsions in the presence of various demulsifiers showed that BDTXI could separate the water in the emulsions more efficiently and faster than the commercial reagents.
Promising Applications of Polyethyleneimine as a Ligand in Rhodium-Catalyzed Tandem Hydroformylation/Hydrogenation of Olefins
Authors: Gorbunov D. N. , Nenasheva M. V. , Kuvandykova E. A. , Kardashev S. V. , Karakhanov E. A.
Published: April 2024

Three rhodium-containing catalytic systems active in tandem hydroformylation/hydrogenation of unsaturated substrates were developed based on polyethyleneimine (PEI): a homogeneous system with distillation of the product; a biphasic system with segregation of the product and catalyst into a non-polar phase and a polar phase, respectively; and a solid catalyst prepared from PEI and (3-chloropropyl)triethoxysilane with its centrifugation from the product mixture. All the systems were shown to be reusable over multiple cycles in hydroformylation/hydrogenation, with the catalytic activity being partially sustained in both steps of the tandem process. Methylation of PEI (or its NH and NH2 moieties in the case of solid material) was found to be critical for the catalytic activity in hydroformylation.
Synthesis and Properties of Polyurea Greases Based on Silicone Fluids and Poly-α-olefin Oils
Authors: Lyadov A. S. , Kochubeev A. A. , Parenago O. P.
Published: April 2024

The paper describes an investigation of lubricants synthesized by thickening a dispersion medium consisting of silicone oil (PES-5) and poly-α-olefin oil (PAOM-12) with diureas of different compositions. The study revealed the effects of the compositions both of the dispersion medium and urea thickener, as well as their ratio in the lubricating formulation, on the major physicochemical properties of resultant greases. Increasing the content of the hydrocarbon component of the grease was shown to improve the physicochemical properties. Finally, the optimum grease composition was identified: introducing a polyurea thickener that contained diphenylmethane-4,4'-diisocyanate resulted in the synthesis of greases that had adequate operating characteristics and an improved wear performance.
tert-Butyl Ethers of Renewable Diols as Oxygenate Additives to Automobile Gasolines. Part II: Ethers of Ethylene Glycol and 2,3-Butanediol
Authors: Samoylov V. O. , Stolonogova T. I. , Ramazanov D. N. , Tyurina E. V. , Sultanova M. U. , Lavrent'ev V. A. , Krasnoshtanova S. S. , Chernysheva E. A. , Kapustin V. M.
Published: April 2024

The results obtained in the second part of the study of vicinal (tert-butoxy)alkanols as additives to automobile gasolines are presented. Mono-tert-butyl ethers of ethylene glycol (ETBE) and 2,3-butanediol (BTBE) were prepared by direct acid-catalyzed alkylation of the corresponding diols with tert-butanol. The substances obtained were characterized by main physical properties (density, viscosity, boiling point, crystallization point, specific heat of combustion) and were studied as additives to automobile gasolines. The effect of ether additives on the main physicochemical properties of gasolines (fractional composition, saturated vapor pressure, concentration of actual resins, knock resistance), including ethanol-containing gasolines, was studied. The mean research/motor blending octane numbers for ETBE and BTBE were 130/103 and 115/97, respectively. Inclusion of ETBE/BTBE into the formulations of ethanol-containing gasolines allowed the cloud point to be considerably reduced without unambiguous synergistic effect on the knock resistance.
Performance of Polysulfones as Components of Ashless Antistatic Additives
Authors: Repina O. V. , Tarazanov S. V. , Nikul'shin P. A.
Published: April 2024

Synthesis of polysulfones from individual α-olefins was investigated. The correlation between the specific electrical conductivity of diesel fuels (DF) and the structure of the initial alkene was identified. The antistatic properties of the synthesized polymers were investigated as a function of the polymer molecular weight and of the dispersant content. The low-temperature properties of DFs that contained a polysulfone as a component of an ashless antistatic additive were further determined.
Composition of Hydrocarbon Gases Formed by Dry Pysolysis of Domanik Shale Kerogen after Hydrothermal Experiment
Authors: Bushnev D. A. , Burdel'naya N. S. , Il'chenko A. A. , Sennikova Ya. D.
Published: April 2024

The composition of hydrocarbon gases formed by pyrolysis of residual Domanik shale kerogen at 800°C, preceded by hydrothermal treatment at 250–375°С, was studied by pyrolytic gas chromatography. Starting from the autoclave temperature of 320–325°C, the hydrothermal treatment of the shale affects the kerogen structures responsible for the formation of C2+ gases in pyrolysis at 800°C. An increase in the temperature of the shale hydrothermal treatment leads to a monotonic increase in the С1/С2+ ratio in the products of the residual kerogen pyrolysis at 800°C. The methane yield at 800°C does not correlate with the content of alkyl structures, determined in kerogen by IR spectroscopy, and the yield of С2+ gases linearly correlates with the content of alkyl structures.
Effects of Nickel Promotion on the Catalytic Performance of In Situ Synthesized Suspensions of Molybdenum Disulfide Nanoparticles
Authors: Zekel' L. A. , Batov A. E. , Visaliev M. Ya. , Kubrin N. A. , Dandaev A. U. , Kadiev Kh. M.
Published: April 2024

The study investigates the activity of in situ synthesized suspensions of nickel-promoted molybdenum disulfide particles in the hydroconversion of crude oil vacuum residues. The catalyst suspensions were prepared in situ from water-in-oil emulsions of aqueous solutions of precursors, specifically ammonium paramolybdate and nickel nitrate. The catalytic tests were carried out in a flow-type reactor at 430°C, WHSV 1 h–1, and 7 MPa hydrogen, with the Mo:Ni atomic ratio in the catalyst particles ranging from 1:0.022 to 1:1.43. The XRD of the toluene-insoluble solids (TIS) extracted from the hydrogenates identified sulfides such as MoS2, Ni3S4, and Ni3S2 in the dispersed catalyst. Increasing the nickel content in the catalyst favored its hydrogenation activity, which was indicated by an enhancement in the feed conversion, an increase in the content of paraffins and naphthenes, and a decrease in the sulfur content in the distillates and TIS derived from the hydrogenates. The conversion of high-molecular-weight feed components (resins, asphaltenes, and heavy aromatics) was enhanced as a result of the nickel promotion of the dispersed MoS2.
Monitoring of Shallow-Water Methane Seeps at Cape Fiolent (Black Sea)
Authors: Malakhova T. V. , Malakhova L. V. , Murashova A. I. , Budnikov A. A. , Ivanova I. N. , Krasnova E. A.
Published: April 2024

During the period from 2019 to 2021, complex studies of new shallow-water methane bubble gas emission sites were carried out in the coastal zone near Cape Fiolent (Southwest Coast of Crimea). The studies included determining the hydrocarbon and isotopic composition of bubble gas, measuring the concentration of methane and nutrients in the water in the areas of gas emissions, estimating the value of bubble flows, and measuring hydrophysical parameters over the sip sites compared to background areas. The seasonal type of Cape Fiolent methane seeps was noted, its active phases of gas emissions differed in duration in different years. The increased pore water silica concentration at the seep sites and their localization in the vicinity of freshwater slope springs may indicate its association with submarine freshwater discharge in the area. However, no significant desalination of both pore water and the bottom water layer above the siphons was recorded. Dissolved methane concentrations in pore water at seep sites were two orders of magnitude higher compared to background areas and reached 448 μmol/L. Also high values were obtained for surface water directly above the bubble gas emission points (maximum 353 nmol/L). Multi-hour monitoring of hydrophysical parameters above the active seeps showed a dissolved oxygen decrease compared to the background sites. The maximum difference in O2 concentrations was 3 mg/l. The carbon isotopic composition of bubble gas methane δ13C-CH4 (–62.84…38.27‰) and сarbon dioxide δ13C-CO2 (–16.83…–10.17‰) was corresponded to a mixture of isotopically heavy gas and near-surface isotopically light gas of microbial origin. The question remains open: what are the reasons for the change in the summer active and the cold season passive gas emission phases?
Seasonal Changes in Abundance, Biomass, and Species Diversity of Zooplankton in Areas Offshore the Crimea (Black and Azov Seas)
Authors: Zagorodnyaya Ju. A. , Drapun I. E. , Galagovets E. A. , Garbazey O. A. , Gubanov V. V. , Kudyakova A. S. , Litvinuk D. A. , Popova E. V.
Published: April 2024

New data are presented the seasonal changes in abundance, biomass of copepods and fodder zooplankton in areas offshore the Crimea. These investigations are based on the materials of five expeditions of the RV “Prof. Vodyanitsky” in the northern part of the Black Sea and the southern part of the Sea of Azov in different seasons of 2016. It was shown: 1) Seasonal differences in the taxonomic structure of the Copepoda taxocene from the shelf and deep waters were revealed. The warm-water invasive species Acartia (Acanthacartia) tonsa and Oithona davisae were relative numerous in the copepod assemblages on the shelf in summer and autumn. In the deep waters, with a low abundance of warm-water invaders, cold-water native species were dominating, and the structure of the Copepoda taxocene was more stable than on the shelf in these seasons. 2) Zooplankton abundance in 2016 was higher compared to 2010 and the 1990s. The data on zooplankton, supported by information about an increase in the species richness and abundance of fish larvae in recent years, make it possible to talk about the transition of the Black Sea ecosystem to a new, relatively stable state.
Influence of Regional Warming on Primary Production of the Kara Sea during the Last Two Decades (2002–2021)
Authors: Demidov A. B. , Gagarin V. I. , Sheberstov S. V.
Published: April 2024

Inter-annual (2002–2021) variability of the Kara Sea PP and associated environmental factors was assessed by MODIS-Aqua data and model calculations. Warming in the Kara Sea region during the last two decades was characterized by the pronounced positive trend of surface water temperature (T0) and weak positive trend of free-ice area (S) averaged for the growing season (April – October). During the investigated period T0 increased by 3.55°C with a trend of 10% y–1 and S increased by 110×103 km2 with a trend of 1.4% y–1, on average. The values of water column PP (IPP) statistically significant (p 0.05) decreased in the all of the Kara Sea regions (R2 = 0.22 – 0.59). For the entire Kara Sea the IPP declined by 38 mgC m–2 d–1 with a moderate trend of 1.1% y–1 (R2 = 0.37). The growing season averaged value of photosynthetically available radiation (PAR) weak, but statistically significant (p 0.05), decreased in the all of the Kara Sea areas (R2 = 0.20 – 0.31). Also, in the all regions the significant (R2 = 0.24 – 0.38) weak or moderate negative trends of surface chlorophyll a (Chl) were specified. The total annual PP (PPtot) increased insignificantly in accordance with increase of S (0.7% y–1, R2 = 0.08). The most significant decline of IPP was specified for spring (R2 = 0.28). In autumn the statistically significant positive trend of S (R2 = 0.24) was observed. Due to such increase of S, the strongest growth of PPtot was noted in autumn. In the present work was shown that decrease of IPP, resulting from decline of PAR and Chl, was the reason of moderation of PPtot. Weak increase in PPtot was observed in autumn and in the north area of the sea. It should be concluded that during the period of intense warming, the decrease in the IPP of the Kara Sea should affect the productivity of the higher trophic levels of the food web.
Physical Modelling of the Formation of the Meteor and Islas Orcadas Rises (South Atlantic)
Authors: Dubinin E. P. , Chupakhina A. I. , Grokholsky A. L.
Published: April 2024

The kinematic reorganization of the plate boundaries in the southeastern part of the Antarctic part of the South Atlantic, which expressed in the jump of the spreading axis of the Agulhas Ridge, has led to a restructuring of the structural plan of the region. This process resulted in the formation of the southern segment of the Mid-Atlantic Ridge (MAR), the extinction of the previously active Agulhas spreading ridge, and the formation of the Meteor and Islas Orcadas rises, marking the location of the MAR and located symmetrically about its axis. Based on the research results, the conditions for jumping the spreading axis were identified and an experimental model was constructed for the formation of accompanying structures, in which an important role was played by the accretion of the oceanic crust on the Agulhas Ridge and the westward migration of the Falkland Plateau. This resulted in the southward movement of the southern segment of the MAR, the formation of the Malvinas microplate, and a jump in the axis of the Agulhas spreading ridge, which led to the cessation of spreading on this ridge. An important role in the process of this kinematic restructuring was played by the activity of the Sean hotspot.
Spatial Structure of Deep-Sea Pelagian Ichthiocenes in the Northern Weddell Sea (Powell Basin) and Brunsfield Strait in the Summer 2020 and 2022
Authors: Kobyliansky S. G. , Mishin A. V. , Orlov А. М. , Gordeeva N. V. , Mukhametyanov R. Z.
Published: April 2024

A review of the composition and structure of deep-sea pelagic ichthyocenes in the Bransfield Strait and the northern part of the Weddell Sea (Powell Basin) in the Atlantic sector of the Southern Ocean is presented. The material was received in the summer of 2020 and 2022 at 26 stations at the layers from 120–0 to 2200–0 m. 901 specimens of juveniles and adult fishes belonging to 19 species from 10 families were collected. Statistical analysis made it possible to identify 4 significantly different regions, in which the dominant ichthyocenes were located in waters of different origin. These ichthyocenes are poor in the number of identified species, but often quite numerous. Relatively shallow-water representatives of the families Bathydraconidae, Channichthyidae, Liparidae, Nototheniidae, endemic to the shelf and slope of Antarctica, dominated in the area of the Antarctic Strait and on the shelf of the Antarctic Peninsula, while in the Bransfield Strait, the abyssal basin of the Powell Basin, as well as in the pelagic zone above deep-sea ridges and trenches, bordering it from the north are meso- and bathypelagic fish from the families Mycthophidae, Bathylagidae, Gonostomatidae, Paralepididae and Scopelarchidae. Near the northern boundary of the Powell Basin, the number of caught mesobatypelagic species and their average abundance were higher than in its central part (11 vs. 7 species and 63.5 vs. 84.1 ind./100 m2). In the central part of the basin, Bathylagus antarcticus dominated, with an average share of 40% in catches and 28.8 ind./100 m2, while in its northern part Electrona antarctica dominated, with an average share of 33% in – 27.4 ind./100 m2.
Concentration and Fluorescence of Chlorophyl a in the Atlantic Sector of Antarctic
Authors: Moiseeva N. А. , Churilova T. Ya. , Efimova Т. V. , Skorokhod Е. Yu. , Artemiev V. A. , Iushmanova A. V.
Published: April 2024

The studies were carried out in cruise 79 of the R/V Akademik Mstislav Keldysh. The variability of the chlorophyll a specific light absorption coefficient of phytoplankton and the coefficient of correlation between the fluorescence intensity and chlorophyll a concentration at various optical depths under basic lighting conditions and after dark adaptation was studied. It is shown that in the absence of water stratification, there is no vertical variability in the chlorophyll a specific light absorption coefficient of phytoplankton. It was found that when measuring the intensity of chlorophyll a fluorescence with a submersible sensor, without preliminary dark adaptation, a decrease in the fluorescence intensity signal in the upper layer of water is observed, which is associated with the effect of illumination on the fluorescence quantum yield.
Hydrological Structure and Water Dynamics in the Powell Basin in January–February 2022
Authors: Mukhametianov R. Z. , Seliverstova A. M. , Morozov E. G. , Frey D. I. , Krechik V. A. , Zuev O. A.
Published: April 2024

In January–February 2022, a CTD/LADCP section across the Powell Basin in the Weddell Sea with hydrochemical observations was carried out in the Antarctic expedition of the R/V “Akademik Mstislav Keldysh”. Transect was located from the Antarctic Peninsula to the South Orkney Islands; thus, it crossed the Weddell Gyre in its northwestern part. As a result, we collected new data about hydrological structure and water dynamics in this area. In this study, we present new results on the data analysis related to the structure of the Weddell Gyre, Antarctic Bottom Water formation, as well as variability of hydrophysical and hydrochemical characteristics of waters in the Powell Basin. Only two of the three currents, Antarctic Coastal Current and Antarctic Slope Front, were identified in the structure of the Weddell Gyre. Velocities of these currents were about 10–15 cm/s. The structure of waters was typical for the Weddell Sea, but a change in the temperature maximum was recorded in the layer of Warm Deep Water.
The Hydrological and Hydrochemical Structure of the Waters of the Bransfield Strait in January 2022
Authors: Seliverstova A. M. , Zuev O. A. , Polukhin A. A. , Chultsova A. L. , Masevich A. V. , Mukhametnyanov R. Z.
Published: April 2024

The work is devoted to the study of the abiotic characteristics in the waters of the Bransfield Strait in January 2022. The cross-section of January 2020 was repeated from the Antarctic Peninsula to the Southern Shetland Islands, as well as new data – 2 cross-sections in the eastern and western parts of the Strait. The scheme of currents in the Strait reflects modern knowledge, absolute values have been measured up to 50 cm/s in the northeast direction and up to 35 cm/s in the southwest. In the studied area, the modified waters of the Sea of Bellingshausen are clearly distinguished (warm and least salted, with reduced values of total alkalinity and all nutrients), the modified waters of the Wedell Sea (colder and salty, with reduced values of silicates and nitrates), as well as Circumpolar Deep Water in layer 200–450 m (warm and salty, with low values of dissolved oxygen and pH and an increased content of phosphates, silicates and nitrates). In the bottom waters of the Strait, there were no serious changes in the structure. The amplitude of the interannual variability of the abiotic characteristics of the waters of the Bransfield Strait is poorly expressed, nevertheless it can serve as a marker of climatic changes in the Southern Ocean.
Spatial and Temporal Variability of the Thermohaline Structure of Waters in the Antarctic Sound
Authors: Zuev O. A. , Frey D. I. , Drozd I. D. , Krechik V. A.
Published: April 2024

The sea straits of the Antarctic Peninsula region are characterized by intense currents, the presence of sea ice and large icebergs, strong tides, and many other factors that form the thermohaline structure of the waters in this region and its temporal variability. The existence of local ecological communities depends on the thermohaline properties of the waters in the straits that determines the relevance of this work. From this point of view, the Antarctic Sound, which connects the Bransfield Strait with the western part of the Weddell Sea, stands out in particular. Based on new field data, a description of the thermohaline structure of this strait is given. Unique data from autonomous sensors installed on marine mammals were used for the first time and made it possible to track changes in the waters throughout the year. The transitional seasons, as well as the general boundaries of the thermohaline characteristics of the waters in the strait, have been determined. The spatial, seasonal and interannual variability of the thermohaline structure of the waters in the strait was studied on the basis of data over the last 40 years.
Reduced Sulfur Compounds in Bottom Sediments of Lakes at Different Stages of Separation from Kandalakshskiy Bay of the White Sea (Meromictic Lake Trekhtzvetnoe)
Authors: Losyuk G. N. , Kokryatskaya N. M. , Vakhrameyeva E. A. , Aliev R. A.
Published: April 2024

The paper presents the results of studying the bottom sediments of the lake Trekhtsvetnoe, which is situated at the meromictic stage of separation from the White Sea (Kandalaksha Bay). The geochemical parameters of the process of bacterial sulfate reduction are considered – the formation and accumulation of various forms of reduced sulfur in relation to the content of organic matter and reactive iron in sediments. A significant level of content of reduced sulfur compounds (up to 1.467%) and their distribution in the sediments of the lake. Tricolor, due to a fairly active process of sulfate reduction. The activity of the recovery processes is ensured by the entry of labile organic matter into the sediments, which is formed due to intensively developing microbial communities in the chemocline zone and in the lake water column.
Investigation of the Regimes of Seiche Oscillations Sevastopol Bay
Authors: Manilyuk Yu. V. , Lazorenko D. I. , Fomin V. V. , Alekseev D. V.
Published: April 2024

Based on the ADCIRC hydrodynamic finite element model, various regimes of seiche oscillations in a narrow extended deep-water bay are studied using the Sevastopol Bay as an example. Long waves penetrating into the bay through its entrance are considered as perturbations. Calculations are made for perturbations with periods of 2.5; 2.9; 6.2 min, belonging to the eigenmodes of the bay with different spatial structure: transverse; longitudinal-transverse, longitudinal, respectively. The impact of these perturbations leads to the generation of not only resonant modes with periods close to the perturbation period, but also an intense Helmholtz mode that occurs after the perturbation ceases and leads to a significant increase in the amplitude of level oscillations. In the studies of seiches caused by perturbations in the form of monochromatic long waves coming from the open sea, it was not possible to confirm that the greatest potential danger to the coastal zone of an elongated deep-water bay is represented by the so-called extreme modes having a transverse structure. A mode with a structure close to transverse was generated, but its maximum amplitude turned out to be 2.5 times less than that of the longitudinal-transverse and longitudinal seiches. The greatest amplification of the incident waves was noted for the longitudinal-transverse mode with a period of 2.9 min.
Population Status of the Ctenophores Mnemiopsis leidyi Agassiz, 1865 and Beroe ovata Bruguiere, 1789 in the Waters of the North and Middle Caspian Western Shelf in August–September, 2022
Authors: Ushivtsev V. B. , Sayapin V. V. , Oleynikov E. P. , Galaktionova M. L. , Kotenkov S. A.
Published: April 2024

The latitudinal distribution of the ctenophores Mnemiopsis leidyi A. Agassiz, 1865 and Beroe ovata Bruguière, 1789 in the Russian sector of the Caspian Sea has different borders of their ranges. Studies on the occurrence of ctenophores in the water column have demonstrated that each species has a characteristic temperature limit of its vertical distribution. Investigations into interactions between ctenophores showed a considerable abundance suppression of M. leidyi (particularly of smaller individuals) by B. ovata.
Acanthomorphic Acritarchs from the Vendian Deposits of Interior Areas of the Siberian Platform
Authors: Golubkova E. Yu.
Published: April 2024

The taxonomic composition of acanthomorphic acritarchs from the Vendian terrigenous deposits of the Prepatom, Nepa-Botuoba, Syugdzhera and Anabar structural-facies districts of the Siberian Platform has been studied. We have found acanthomorphic microfossils at three stratigraphic levels: in the lower and upper parts of the Nepa Regional Stage and in the lower subformation of the Byuk Formation of the Tira Regional Stage. Monographic description of new acritarchs Tanarium longidigitatum sp. nov., Tuberculum proteum sp. nov., Uniexcrescentia tubulosa gen. et sp. nov. and Pterospermopsimorpha mutabilis sp. nov. was carried out.
The Species Palmatolepis tatarica Ovnatanova et Gatovsky, 2020: History of Its Separation and Interpretation in the World Literature on Conodonts of the Late Devonian
Authors: Ovnatanova N. S. , Kononova L. I.
Published: April 2024

The article is devoted to a subspecies of Pa. subperlobata, the name of which changed for more than half a century from Pa.subperlobata subsp. a of Helms to the name Pa. subperlobata helmsi Ovnatanova, 1976 and subsequent renames associated, as it turned out later, with the preocupation of the name helmsi. In the article, this subspecies is considered as an independent species and the similarities and differences of the holotype species Pa. tatarica Ovnatanova et Gatovsky, 2020 (=Pa. subperlobata helmsi Ovnatanova) with the holotypes of species recommended as replacement of the preocupied name are discussed. The author’s scheme of phylogenetic development of the Pa. subperlobata group is proposed.
Palaeoulvaria Green Algae of the Vendian (Ediacaran) Berezovsky Trough (South of the Siberian Platform)
Authors: Kolosov P. N.
Published: April 2024

Microorganisms of unique preservation were found in the Byuk formation of the Vendian (Ediacaran) of the Berezovsky trough in the southeast of the Siberian platform. These microorganisms are present in the silicified colloform stromatolites, i.e. they inhabited the littoral and sublittoral zones. The microorganisms are characterized by a lamellar body-type, rods between plates that attach them, and reproductive organ on the stipe. Based on these characteristics typical of Ulvaceae, the described microorganisms are to be representatives of green algae (Chlorophyta), belonging to the order Ulvales Blackman et Tansley, and presumably corresponding to the family Anchicodiaceae Shuysky, 1987. A new genus Palaeoulvaria with the type species P. plate gen. et sp. nov. was identified.
The First Finds of Representatives of the Order Acrotretida Kuhn from the Frasnian (Upper Devonian) Deposits of Komi Respublic
Authors: Smirnova T. N. , Zhegallo E. A.
Published: April 2024

The structure and microstructure of the shell substance Acrotretella sp. on the protegulum, brephic and adult shell. The structure of the secondary layer, represented by interlayers with columnar-lamellar and spherulite structures, is characteristic. Wrinkles are developed along the edges of the shell.
New Nautilida from the Shakhtau Asselian-Sakmarian Reef Complex (Bashkortostan)
Authors: Leonova T. B. , Shedukhin A. Yu.
Published: April 2024

This paper describes new nautilids from the Shakhtau Asselian–Sakmarian reef complex. Their place in the nautilid system, which is still far from being completely understood, is discussed. Two species of two genera: Omorphoceras igori gen. et sp. nov. and Stenopoceras (Leptodomatoceras) bashkiricum subgen. et sp. nov. are assigned to the subfamily Domatoceratinae Miller et Youngquist, 1949, family Grypoceratidae Hyatt, 1900. The third, Foveroceras magnum gen. et sp. nov., is included in the exotic family Permoceratidae Miller et Collinson, 1953, which was previously considered monotypic and was known only from the Early Permian of Timor Island. The classification of the family Grypoceratidae is discussed, and the validity of the subfamily Domatoceratinae is questioned. The assumed phylogenetic relationship between the families Grypoceratidae and Permoceratidae is confirmed.
Some Morphofunctional Features of the Tail of Early Archosaurs in Relation to Swimming Adaptation
Authors: Sennikov A. G.
Published: April 2024

In ancient and modern aquatic and semi-aquatic tetrapods, several types of structure of the locomotor apparatus are presented, providing various styles of swimming. In the course of evolutionary adaptation to swimming, an important role was played by the morphological transformations of the tail, which often performs the main propulsion function. Modern reptiles (except turtles) swim mainly with the help of horizontal tail bends, while mammals swim either vertical or horizontal ones. Among extinct reptiles, Sauropterygia probably used vertical tail mobility when swimming. In most archosauromorphs, the tail became high, laterally compressed, and they swam mainly with the help of its horizontal movements. Among early archosaurs, Proterohampsians and Doswelliids are distinguished by their wide and dorsoventrally flat tails, which may indicate an adaptation to swimming using its vertical mobility.
Shell Ontogeny of the Type Species of the Genus Neouddenites (Ammonoidea, Medlicottiidae) from the Kungurian of Western Verkhoyanie
Authors: Kutygin R. V.
Published: April 2024

Reconstructions of the cross sections of two specimens of the type species of Neouddenites, N. andrianovi Ruzhencev from the Kungurian of Western Verkhoyanie revealed features of its ontogenetic development. The species is characterized by slow extension of the medial spiral, which only stops at the last whorl. The shell shape continuously changes from very wide at the first whorl to very narrow at the last whorl. The umbilicus at the beginning of ontogeny expands slightly, making the shell evolute. The umbilicus then strongly narrows, and at the last whorls the shell acquires a completely involute shape. Significant changes in the shape of the whorl cross section are observed throughout ontogeny allowing recognition of four successive stages, designated as “Eocanites”, “Pronorites”, “Prouddenites”, and “Neouddenites”. Neouddenites andrianovi was found to lack lateral grooves and ventrolateral ridges, previously considered to be diagnostic characters of the genus Neouddenites.
Clarification of the Systematic Position of the Weevils (Coleoptera) Described from the Middle Eocene of Germany
Authors: Legalov A. A.
Published: April 2024

The genera Palaeoalatorostrum Rheinheimer, 2007 and Cryptorrhynchites Haupt, 1950 are transferred from the tribe Otiorhynchini of the subfamily Entiminae (Curculionidae) and from the tribe Cryptorhynchini of the subfamily Molytinae (Curculionidae), respectively, to the tribe Attelabini of the subfamily Attelabinae of the family Attelabidae; genera Palaeocrassirhinus Rheinheimer, 2007 and Palaeocneorhinus Rheinheimer, 2007 are transferred from the tribes Anypotactini and Cneorhinini, respectively, to the tribe Brachyderini. A key to the species of the genus Palaeocrassirhinus is given.
A New Species of the Family Electrotomidae (Hymenoptera, Symphyta, Tenthredinoidea) from the Baltic Amber
Authors: Rasnitsyn А. P. , Manukyan A. R.
Published: April 2024

The species Electrotoma kopylovi sp. nov. is described by the larva (prepupa) from the Upper Eocene Baltic amber. It is the second find of the fossil of Electorotomidae family. The new species differs from the only previously known E. succini Rasnitsyn, 1977 in the closer placed antenna and stemma, less shortened clypeus, symmetrical labrum and a richer head and thorax chetotaxy. The composition of E. kopylovi syninclusions proves the previously stated hypothesis suggesting a combination of some non-standard circumstances that caused electrotomids to get into the resin.
Ovis gracilis sp. nov. (Artiodactyla, Bovidae) in the Lower Pleistocene of the Taurida Cave in the Crimea and the History of the Genus Ovis
Authors: Vislobokova I. A.
Published: April 2024

А new species Ovis gracilis sp. nov. is described based on the study of fossil remains of Bovidae from the Lower Pleistocene of the Taurida Cave, the Crimea. This not very large sheep had the horn cores with homonymous torsion and short sinuses, and slender metapodia. The remains of Ovis from Taurida are among the oldest in Europe and the first evidence of the presence of Ovis in the Еarly Pleistocene of the Crimea. The species O. gracilis was a part of the fauna of the Taurida Cave, dated within 1.8–1.5 Ma. The appearance of this species in the south of Eastern Europe could be associated with one of the early waves of dispersal from Asia, along the Alpine-Himalayan belt just prior to the Olduvai paleomagnetic episode.
Small Ducks (Aves: Anatidae) from the Early–Middle Miocene of Eurasia. 2. The Fauna of Tagay Locality (Baikal Area; Eastern Siberia)
Authors: Zelenkov N. V.
Published: April 2024

Remains of small ducks are described from the boundary early–middle Miocene deposits of Tagay (Baikal area), the only locality in Asia with a representative bird fauna of the Miocene climatic optimum. New taxa Mioquerquedula palaeotagaica sp. nov. and Tagayanetta palaeobaikalensis gen. et sp. nov., corresponding in size to modern Anas crecca, as well as an even smaller duck Selenonetta lacustrina gen. et sp. nov. are described. A revision of the genus Mioquerquedula is undertaken; “Anas” integra Miller, 1944 from the Lower Miocene of North America is here transferred to this genus. Tagayanetta gen. nov. is here considered as an evolutionarily more advanced genus than Mioquerquedula, probably close to Anatini. Selenonetta gen. nov. is considered as a taxon close to the divergence between Mergini and other Anatinae. A similar form (possibly the same species) is present in the Sansan locality (France).