Saint Petersburg Mining University

Pegmatites with miarolitic cavities have not previously been reported from the Larsemann Hills, East Antarctica, and their age and origin remain poorly constrained. We report the first geochemical and geochronological data for fluorapatite from a newly discovered pegmatite with miarolitic cavities in the Larsemann Hills. Large Fe-rich fluorapatite crystals (up to 5 cm) contain abundant oriented monazite-(Ce) inclusions and display elevated REE (1397–7966 ppm), relatively high Y (945–4192 ppm), and low Sr (52.2–83.5 ppm). Their trace-element signatures plot within the fields of partial melts, high-grade metamorphic rocks, and evolved fluid-rich magmatic systems. U–Pb dating of fluorapatite yields concordant ages of 519 ± 4 Ma (ID-TIMS) and 521 ± 31 Ma (LA-ICP-MS), indicating crystallization during the D4 stage of the Pan-African orogeny. The isotopic equilibrium between apatite and monazite inclusions suggests synchronous formation and late-stage fluid overprinting. Combined geological, geochemical, and isotopic evidence shows that the pegmatite formed in situ as a product of anatexis of the Broknes paragneisses and evolved within a volatile-rich magmatic–hydrothermal system. These results provide the first direct age constraints on pegmatites with miarolitic cavities in Antarctica and shed new light on the final stages of East Gondwana assembly.

An analysis of the renewable energy sources potential in Vietnam has shown that the energy balance in the context of energy transition can be transformed and include solar, wind, hydrogenation, as well as biomass energy production. The purpose of the study is to develop a methodological approach to a comprehensive feasibility study of renewable energy sources, considering their competition, and substantiate the prospects for developing low-carbon energy in Vietnam. The subject of the study is various technical, economic, social, and environmental parameters of renewable energy sources. A methodology has been developed for a comprehensive feasibility study of renewable energy sources, including the statistical data collection and analysis, basic technologies analysis, and the hierarchy method for predicting the energy balance structure. It has been established that, according to the technical characteristics, small hydroelectric power plants and biomass-based generation are the most mature and efficient, solar generation is the least expensive and most effective type according to economic indicators, all types of renewable energy are comparable and supported by the public according to environmental criteria, and biomass energy production significantly loses, while other types of generation are comparable. The study results showed the role of renewable energy sources in Vietnam’s energy strategy and priorities in their development in terms of the competitiveness of various types of renewable energy sources. The study results can be used to plan the energy balance structure and select government support measures for the energy sector.

Taxonomic composition and biostratigraphic distribution of organic-walled microfossils and trace fossils are analyzed in Skvieryki-1s and Vychulkovskaya-201 boreholes at the southern Podlassko-Brest Depression in Belarus. The studied sections host three assemblages: two of the Lower Cambrian age corresponding to Rovno–Lontova and Dominopol’–Vergale–lower Rausve regional stages and one in the Lower–Middle Cambrian strata (upper Rausve–Kybartai regional stages). The new data expand the paleontological characteristic of the Lower Cambrian. For the first time, isolated sclerites of Wiwaxia sp. and undescribed microfossils provisionally interpreted as fragments of a mollusk radula are found in the Bug and Velikovichi formations in Belarus. These stratigraphic units also host horizontal and vertical burrows. These biostratigraphic data will help for future paleobiological, stratigraphic and paleogeographic studies.

Accurate prediction of the rheological behavior of heavy crude oil mixtures is essential for pipeline transport under cold climate conditions. This study presents a physically based non-Newtonian rheological model that incorporates the coupled effects of temperature and mixture composition through temperature- and concentration-dependent expressions for the consistency coefficient and flow behavior index. The model was calibrated and validated using 88 experimental rheological measurements on binary mixtures of heavy Severo-Komsomolskoye and light Vankor crudes over a temperature range of 5C–60 °C, heavy-oil concentrations of 0%–100%, and shear rates of 1–300 s -1 . The proposed model predicts shear stress with a mean relative deviation of 8.7% and a root mean square error below 0.95 Pa, outperforming conventional Arrhenius, Refutas, and classical power-law correlations by a factor of 2–3. The model accurately captures the transition from non-Newtonian to near-Newtonian behavior with increasing temperature and dilution, providing a practical tool for hydraulic calculations and flow assurance design in cold-region pipeline systems.

Venepuncture is the most common invasive procedure in modern medical practice, with the nurse playing a pivotal role in ensuring its quality and safety. This paper presents a comprehensive approach to performing venepuncture, encompassing patient preparation, establishing effective communication, selecting optimal consumables, and assessing the cost-effectiveness of the systems used. The algorithm for preparing and performing the procedure is analyzed in detail, along with the specifics of working with different patient categories and methods for preventing complications. Particular emphasis is placed on the nurse's educational role and the formation of patient motivation for active cooperation. It is demonstrated that the quality of consumables directly impacts not only the reliability of laboratory test results but also the ergonomics of the nurse's work, the frequency of repeated procedures, and the overall cost-effectiveness of the diagnostic and treatment process.

Riedel shears, formed under the action of shear stresses in rocks, are an important element in studying the nature of tectonic deformations. This work investigates their formation using acoustic emission (AE) during triaxial compression experiments. We identify four fracture stages: Stage 1: Dispersed microcracks at 40–80% peak stress. Stage 2: Localized macrofracture nucleation at 0.99σ (tensile strength), with AE activity surge (300–500% increase). Stage 3: Shear deformation along faults. Analyzing the mechanisms of formation of such fracture systems allows identifying patterns of rock failures, which in turn enables predicting the nature of geodynamic processes. This study examines the relationship between local geomechanical processes of Riedel shear formation and global tectonic faults. To address this issue, theoretical and experimental modeling of stress distribution in rock samples under triaxial compression was conducted, along with the analysis of geophysical data confirming the patterns of formation of en echelon fracture systems in natural conditions. As a result of the study, the features of Riedel shear development in idealized (modeled) and real geological environments were determined, and key factors indicating the connection between fracturing and shear deformation zones were identified. The obtained results can be used for interpreting tectonic structures and predicting geomechanical events. A new approach to the interpretation of acoustic emission for predicting shear deformations on the scale of a rock massif has been developed. A novel AE interpretation methodology links hypocenter concentration to shear zones, validated against the 2020 Bystrinskoe earthquake precursors. Results enable predicting geomechanical events and hydrocarbon migration paths.

The oil and gas industry uses austenite stainless steels because of their high strength, flexibility, and resistance to the impacts of the atmosphere, damp environment, acids, salts, and other harsh chemicals. Problems in machining of such steels are associated with the formation of drain chip, their adhesion to the edge of the tool with the formation of build-up and the emergence of vibrations, which complicates the machining process and reduces its quality. The complexity of machining places greater demands on the tool used, the rigidity of technological equipment mandates the use of coolant, and various ways of chip removal. The scientific novelty consists in the fact that development of a method matches local cryogenic treatment with mechanical processing, ensuring automatic chip breaking and increased productivity. The influence of the method of cryogenic treatment on the structure, properties and machinability of austenitic steels was evaluated on the most common steel grade 08Kh18N10T. The formation of a magnetic martensitic phase with increased hardness at the boundaries of austenitic grains, which causes a change in the mechanism and conditions of chip formation in the local zone, acts as a stress concentrator, resulting in drain chip segmentation and improved machinability. The main findings include an analysis of the method's impact on the dynamic stability of the mechanical processing technological system; reduction of surface roughness by 2 times during mechanical processing with local cryogenic treatment compared to conventional cutting; ensuring stable segmentation and uniform fragmentation of the chip.

The article is devoted to the analysis of modern methods of monitoring main pipelines used to identify dangerous deformation processes that can disrupt the integrity of the pipeline. The paper discusses technologies for in-line inspection, fiber-optic sensors, and highly accurate geodetic observations using an electronic total station, satellite positioning systems, and radar interferometry (InSAR). Special attention is paid to integrated approaches, including a set of methods that allow automated data collection and processing using machine learning algorithms. A two-stage monitoring is proposed: regional, including the zoning of vast territories according to the degree of risk, taking into account natural and climatic conditions, man-made factors, and local, based on the analysis of deformations of the «ground surface – pipeline» system, performed through observations of points of geodetic deformation networks. The key advantages of the approach are adaptability to various operating conditions, optimization of resource intensity and early warning of defects.

This study conducts a comparative geological and economic assessment of uranium resources in Russia and Iran, with a focus on their ability to support the development of domestic nuclear energy. Unlike previous research, which has predominantly examined Russian–Iranian cooperation from political or institutional perspectives, this work evaluates uranium availability using geological classifications and economic cost categories of reserves. It distinguishes between recoverable resources reported for Russia and in situ resources reported for Iran, with the latter converted to a comparable basis through the application of appropriate recovery factors. In addition to analyzing the structure and potential of the resource base, the study takes into account historical and projected uranium production as well as consumption scenarios for both countries. On this basis, long-term self-sufficiency horizons are estimated through 2045. The findings show that Russia possesses a vast and geologically diverse uranium base, capable of ensuring long-term supply if new mining projects are developed to offset the expected decline in production after 2030. Iran, by contrast, holds more limited and higher-cost reserves, concentrated mainly in metasomatite deposits, which makes the achievement of sustained self-sufficiency unlikely without external cooperation or technological breakthroughs. At the same time, geological similarities between the two countries create a basis for potential collaboration in uranium exploration and development. By addressing a relatively underexplored aspect of the literature, this study provides a structured assessment of uranium supply sustainability and introduces a comparative perspective relevant not only to Russia and Iran but also to other countries with emerging nuclear programs.