Search Results (23)

An in-depth study of the genetic mechanisms of graphite in shear zones is crucial for understanding crustal weakening and the origins of inorganic carbon. This research focuses on mylonitic marble (MM) and cataclastic marble (CM) from the Tongyuanpu shear zone of Eastern China. The occurrences, nanostructures, carbon sources, and genesis of graphite were systematically investigated through micro- to ultra-microscale analysis. The results reveal that the MM contains two graphite varieties: C-foliation-aligned bands and stylolite-derived serrated aggregates. Both exhibit strong Z-axis LPO, indicating a deformation temperature below 200 °C. In contrast, the CM features individual graphite particles within fragmented grains. Near-ideal graphite structures are characterized in both types; however, a higher TOC content and a greater graphitization degree are observed in the CM. Raman thermometry indicates metamorphic peak temperatures of 588–673 °C (MM) and 540–682 °C (CM), with the former showing a significant discrepancy from the EBSD results. The δ¹³C_ORG values (−12.21‰ to −8.06‰) suggest fluid-derived carbon sources. We propose that reduction reactions involving high-temperature metamorphic fluids supplied the essential carbon source. Ductile shearing accelerated the graphitization of these carbonaceous materials through the accumulation of local strain energy, while subsequent brittle deformation with frictional sliding further facilitated structural transformation. Full article

Diamond, a crucial carbon phase in the deep Earth, forms under ultrahigh-pressure (UHP, P > 4 GPa) conditions and serves as an important indicator mineral for the UHP environment. Based on their host rocks, diamonds are classified into mantle-derived diamonds, UHP metamorphic diamonds, impact diamonds, etc. While carbon constitutes the primary component of diamonds, nitrogen represents one of the most significant impurity elements. The study of the occurrence mode of nitrogen and the C-N isotope composition is essential for exploring the formation mechanism of diamond. Nitrogen primarily exists in diamonds as either isolated atoms (N) or aggregated forms (N2 or N4), with the dominant mode being controlled by temperature and residence time in the mantle. As temperature and residence time increase, isolated nitrogen progressively transforms into aggregated forms. As a result, mantle-derived diamonds typically contain nitrogen predominantly as N2 or N4, whereas metamorphic diamonds and impact diamonds mainly retain isolated N. Global C-N isotopic composition of over 4400 diamonds reveals a wide compositional range, with δ¹³C ranging from −38.5‰ to +5.0‰, and δ¹⁵N from −39.4‰ to +15.0‰. These values significantly exceed the typical mantle δ¹³C and δ¹⁵N values of −5‰ ± 3‰, indicating that the diamond formation may be influenced by subducted crustal materials. During crystallization, diamonds can encapsulate surrounding materials as inclusions, which are divided into three types based on their formation sequence relative to the host diamond: preformed, syngenetic, and epigenetic. Syngenetic inclusions are particularly valuable for constraining crystallization conditions and the genesis of diamonds. Furthermore, geochronology studies of radioactive isotope-bearing syngenetic inclusions are helpful to clarify the age of diamond formation. Usually, mantle-derived diamonds exhibit Archean age, whereas metamorphic diamonds are associated with subduction, showing younger ages that could be associated with metamorphic events. Therefore, the formation conditions and genesis of diamonds can be clearly constrained through integrating investigations of inclusions, nitrogen occurrence modes, and C-N isotopic compositions. The characteristics of occurrence modes, inclusions, and C-N isotope compositions of different types of diamonds are systematically reviewed in this paper, providing critical insights into their genesis and contributing to a deeper understanding of diamond formation processes in Earth’s interior. Full article

The occurrence of gypsum in clastic rocks of continental saline lake basins reflects complex depositional and diagenetic processes. However, its genesis remains relatively understudied. Based on core descriptions and thin-section analyses, this study investigates the occurrence types and genetic mechanisms of gypsum in the Bottom Sandstone Member of the northern Tabei Uplift. Five types of gypsum occurrences are identified: layered gypsum, gypsum clasts, spotted gypsum, gypsum nodules, and a mixed deposition of clastic rocks and gypsum. The mixed deposition of clastic rocks and gypsum includes gypsiferous mudstone, muddy gypsum, gypsiferous mudstone containing muddy clasts, and sandy gypsum. Layered gypsum, spotted gypsum, gypsiferous mudstone, and muddy gypsum mainly result from in situ chemical precipitation during periods of high evaporation and reduced runoff. In contrast, gypsum clasts, gypsiferous mudstone containing muddy clasts, and sandy gypsum reflect processes of transportation and reworking induced by flood events. Seasonal variations in hydrodynamic conditions play a critical role in the formation and distribution of gypsum. During dry periods, surface runoff weakens or ceases, and the salinity of lake water or pore water in clastic deposits increases due to intense evaporation, promoting gypsum precipitation. During flood periods, increased runoff can erode previously formed gypsum, which is subsequently transported and deposited as gypsum clasts. The morphology of gypsum varies with its transport distance. These findings enhance our understanding of clastic–evaporite mixed systems in arid continental lacustrine settings and provide insights into sedimentary processes influenced by seasonal climatic fluctuations. Full article

It is known that a number of neurodegenerative diseases, also called diseases of waiting, are associated with the expansion of the polyQ tract in the first exon of the ATXN2 gene. In the expanded polyQ tract, the probability of occurrence of non-canonical configurations (hairpins, G-quadruplexes, etc.) is significantly higher than in the normal one. Obviously, for their formation, the occurrence of open states (OSs) is necessary. Calculations were made for these processes using the angular mechanical model of DNA. It has been established that the probability of the large OS zones genesis in a DNA segment depends not only on the “strength” of the nucleotide sequence but also on the factors determining the dynamics of DNA; localization of the energy in the DNA molecule and the potential energy of interaction between pairs of nitrogenous bases also depend on environmental parameters. The potential energy of hydrogen bonds does not remain constant, and oscillatory movements lead to its redistribution and localization. In this case, OSs effectively dissipate the energy of oscillations. Thus, mathematical modeling makes it possible to calculate the localization of mechanical energy, which is necessary for the OSs formation, and to predict the places of their origin, taking into account the mechanical oscillations of the DNA molecule. Full article

The Dapingzhang Cu-polymetallic deposit in Yunnan is a volcanic massive sulfide (VMS) deposit, located on the western edge of the Lanping–Simao block. Recently, gold-rich polymetallic orebodies with significant economic value have been discovered. However, the occurrence and enrichment mechanisms of the gold remain unclear. This study investigates the massive sulfide orebodies (V₁) through detailed geological surveys. Techniques such as optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron probe microanalysis (EPMA) were used to clarify the occurrence of gold, and to reveal the enrichment mechanisms. The genesis of the orebodies consists of three stages: (I) pyrite–quartz, (II) pyrite–chalcopyrite–sphalerite–galena–quartz, and (III) pyrite–chalcopyrite–sphalerite–galena–quartz–calcite. Gold precipitated during each of these mineralization stages, and it may be described as multiphase mineralization. Gold predominantly exists as invisible gold (≤0.1 μm), with minor visible gold as native gold and independent minerals (küstelite, electrum, calaverite). Invisible gold mainly occurs as gold microinclusions (Au⁺) in pyrite, chalcopyrite, and sphalerite. Combined with the previous research, comprehensive analysis determined that deep-circulating seawater, driven by a magmatic hydrothermal system, leaches and dissolves mineralizing materials from underlying volcanic rocks. The mineralizing fluid, mixed with magmatic fluid, migrates upward through volcanic conduits or is expelled to the seafloor. Changes in physicochemical conditions lead to the co-precipitation of gold and sulfides, forming a mineralization structure with lower channel facies and upper eruptive facies. Full article

The North Aegean Sea region in Greece is located at the convergence of the Eurasian, African, and Anatolian tectonic plates. The region experiences frequent seismicity ranging from moderate to large-magnitude earthquakes. Tectonic interactions and seismic events in this area have far-reaching implications for understanding the broader geological processes in the eastern Mediterranean region. This study aims to conduct a comprehensive investigation of the seismic activity of the North Aegean Sea region by employing advanced seismological techniques and data analyses. Data from onshore seismological networks were collected and analyzed to assess the characteristics of the earthquakes in the region. Seismicity patterns, focal mechanisms, and seismic moment calculations were performed to assess current seismic activity. The present study combined spatiotemporal analysis with the analysis of genesis mechanisms, and this resulted in more results than those of previous studies. Detailed analysis of the seismic data showed patterns in the occurrence of earthquakes over time, with periodic episodes of increased seismic activity compared to activities followed by quieter periods. Finally, this study proves that recent earthquakes in the study area (2017, 2020) highlight the complexity of seismicity as well as the consequences of strong earthquakes on people and buildings. Overall, these findings suggest that the North Aegean Sea is becoming increasingly seismically active and is a potential risk zone for adjacent regions. Full article

Sleep deprivation (SD) is a recognized risk factor for atrial fibrillation (AF), yet the precise molecular and electrophysiological mechanisms behind SD-induced AF are unclear. This study explores the electrical and structural changes that contribute to AF in chronic partial SD. We induced chronic partial SD in Wistar rats using a modified multiple-platform method. Echocardiography demonstrated impaired systolic and diastolic function in the left ventricle (LV) of the SD rats. The SD rats exhibited an elevated heart rate and a higher low-frequency to high-frequency ratio in a heart-rate variability analysis. Rapid transesophageal atrial pacing led to a higher incidence of AF and longer mean AF durations in the SD rats. Conventional microelectrode recordings showed accelerated pulmonary vein (PV) spontaneous activity in SD rats, along with a heightened occurrence of delayed after-depolarizations in the PV and left atrium (LA) induced by tachypacing and isoproterenol. A Western blot analysis showed reduced expression of G protein-coupled receptor kinase 2 (GRK2) in the LA of the SD rats. Chronic partial SD impairs LV function, promotes AF genesis, and increases PV and LA arrhythmogenesis, potentially attributed to sympathetic overactivity and reduced GRK2 expression. Targeting GRK2 signaling may offer promising therapeutic avenues for managing chronic partial SD-induced AF. Future investigations are mandatory to investigate the dose–response relationship between SD and AF genesis. Full article

The Woka-Cuona rift zone on the southeastern side of the Qinghai-Tibet Plateau is characterized by complex geological background conditions, comprising three independent or semi-grabens that traverse from south to north across the Himalayan and Gangdise terranes. Conducting research on the distribution patterns and genesis mechanisms of geothermal resources within the Woka-Cuona rift zone has certain guiding significance for understanding the genesis mechanisms of the geothermal system in the southern Tibetan rift and its exploitation. This paper utilized methods such as data collection, ground investigations, and geochemical analyses to analyze the distribution characteristics and evolutionary processes of geothermal waters in the Cuona rift area based on the geological background conditions of the study area. The research findings demonstrate a significant correlation between the occurrence of geothermal waters in the Cuona rift zone and geological structures, with most geothermal waters primarily distributed near intersections of graben boundary faults and east–west-trending faults. Different regions exhibit variations in the intensity of geothermal activity and geochemical characteristics, with the genesis of geothermal waters associated with deep magmatic activity, characterized by Na⁺ and K⁺ as the primary cations and Cl⁻ as the primary anions. Geothermal waters mainly originate from atmospheric precipitation and snowmelt water from surrounding mountainous areas, with recharge elevations ranging from 4500 to 6200 m and an average elevation of 5400 m. Full article

Sirtuins (SIRTs) are stress-responsive proteins that regulate several post-translational modifications, partly by acetylation, deacetylation, and affecting DNA methylation. As a result, they significantly regulate several cellular processes. In essence, they prolong lifespan and control the occurrence of spontaneous tumor growth. Members of the SIRT family have the ability to govern embryonic, hematopoietic, and other adult stem cells in certain tissues and cell types in distinct ways. Likewise, they can have both pro-tumor and anti-tumor effects on cancer stem cells, contingent upon the specific tissue from which they originate. The impact of autophagy on cancer stem cells, which varies depending on the specific circumstances, is a very intricate phenomenon that has significant significance for clinical and therapeutic purposes. SIRTs exert an impact on the autophagy process, whereas autophagy reciprocally affects the activity of certain SIRTs. The mechanism behind this connection in cancer stem cells remains poorly understood. This review presents the latest findings that position SIRTs at the point where cancer cells and autophagy interact. Our objective is to highlight the various roles of distinct SIRTs in cancer stem cell-related functions through autophagy. This would demonstrate their significance in the genesis and recurrence of cancer and offer a more precise understanding of their treatment possibilities in relation to autophagy. Full article

The surface currents in coastal areas are closely related to the ecological environment and human activities, and are influenced by both local and remote factors of different timescales, resulting in complex genesis and multi-timescale characteristics. In this research, 9-year-long, hourly high-frequency radar (HFR) surface current observations are utilized together with satellite remote sensing reanalysis products and mooring data, and based on the Empirical Orthogonal Function (EOF) and correlation analysis, we revealed the multi-timescale characteristics of the surface currents in Fremantle Sea (32°S), Southwestern Australia, and explored the corresponding driving factors as well as the impact of El Niño-Southern Oscillation (ENSO) on the nearshore currents. Results show that the currents on the slope are dominated by the southward Leeuwin Current (LC), and the currents within the shelf are dominated by winds, which are subject to obvious diurnal and seasonal variations. The strong bathymetry variation there, from a wide shelf in the north to a narrow shelf in this study region, also plays an important role, resulting in the frequent occurrence of nearshore eddies. In addition, the near-zonal winds south of 30°S in winter contribute to the interannual variability of the Leeuwin Current at Fremantle, especially in 2011, when the onshore shelf circulation is particularly strong because of the climatic factors, together with the wind-driven offshore circulation, which results in significant and long-lasting eddies. The southward Leeuwin Current along Southwestern Australia shows a strong response to interannual climatic variability. During La Niña years, the equatorial thermal anomalies generate the westward anomalies in winds and equatorial currents, which in turn strengthen the Leeuwin Current and trigger the cross-shelf current as well as downwelling within the shelf at Fremantle, whereas during El Niño years, the climate anomalies and the response of coastal currents are opposite. This paper provides insights into the multi-timescale nature of coastal surface currents and the relative importance of different driving mechanisms. It also demonstrates the potential of HFR to reveal the response of nearshore currents to climate anomalies when combined with other multivariate data. Meanwhile, the methodology adopted in this research is applicable to other coastal regions with long-term available HFR observations. Full article

Various types of pores, including organic and inorganic variations, exhibit distinct impacts on the storage capacity of shale gas reservoirs and play a significant role in shale gas occurrence. However, there is a limited number of studies that have quantitatively addressed the developmental characteristics of these diverse pore types and their primary controlling factors. This paper explores the development of inorganic pores, specifically interparticle pores and intraparticle pores, as well as organic matter (OM) pores within the shales of the Wufeng–Longmaxi Formation in the Upper Yangtze region. Parameters such as areal porosity, pore diameter, and pore number based on the FE-SEM and image digitization are discussed. Additionally, the influence of the sedimentary environment on the development of various pore types through integrated wavelet transform techniques and geochemical analysis are analyzed. This analysis reveals the distinctive mechanisms governing the development of pore types under the sequence stratigraphic constraints. The findings reveal that the Wufeng–Longmaxi Formation within the study area can be classified into four systems tracts (transgressive systems tracts TST1 and TST2, and highstand systems tracts HST1 and HST2). Within TST1+HST1, OM pores emerge as the predominant pore type, contributing to over 65% of the porosity. TST2 similarly displays OM pores as the dominant type, comprising over 45% of the total porosity, with an average OM areal porosity of 7.3%, notably lower than that of TST1+HST1 (12.7%). Differences in OM pore development between TST1+HST1 and TST2 shales are attributed to variations in OM abundance and type. In HST2, inorganic pores are the dominant pore type, primarily consisting of interparticle pores associated with clay minerals, contributing to more than 50% of the porosity, while OM pores remain almost undeveloped. The frequent sea level fluctuations during the sequence stratigraphic evolution caused variations in sedimentary environments across different depositional sequences. These differing depositional environments lead to varying OM content and types, mineral genesis, and content, ultimately resulting in disparities in the development of shale pore types within different sequences. Full article

Selenium and Te are two important critical metals, which are often produced as by-products in Au-Cu deposits related to magmatic–hydrothermal systems, such as porphyry and skarn deposits. The Jilongshan Au-Cu deposit is a typical skarn deposit located in the middle and lower parts of the Yangtze River metallogenic belt. Previous studies show that it has valuable Se and Te resources, but their occurrence, particularly the relationship between the texture and composition of pyrite, and the enrichment mechanism of Se, Te, and Au remain unclear. Here, the textures and the major and trace elements of the Jilongshan pyrites were studied by using an optical microscope, EMPA, and LA-ICP-MS to reveal the occurrence of Se, Te, and Au in pyrite, as well as their genetic links with the pyrite mineralogical signature. The results show that there are three types of ores in the Jilongshan deposit, including granite porphyry-hosted, skarn-hosted, and carbonate-hosted ores. All of these ores contain major amounts of pyrite, which can be divided into four different generations. The first generation of pyrite (Py1) belongs to sedimentary genesis with a typical framboid texture and its Co/ Ni ratios are less than 1, whereas Py2, Py3, and Py4 belong to hydrothermal genesis and their Co/ Ni ratios are between 1.0 and 30.2. Selenium concentrations in Py2 and Py3 are relatively high (median, 138 ppm and 344 ppm, respectively), which are mainly present as isomorphism and a small amount as selenite in pyrite. Compared with granite porphyry-hosted and skarn-hosted ores, pyrite from carbonate-hosted ores has the highest Se concentrations. The latest generation of pyrite (Py4) contains the highest concentrations of Te (average, 140 ppm) and Au (average, 12 ppm) among the hydrothermal pyrites. Therefore, the precipitation of Se mainly occurs in pyrite during the early high-temperature stage, whereas higher concentrations of Te and Au are mainly enriched in pyrite during the late stage with low temperatures. Full article

Introduction: In all cases of cardiac arrest, adequate cardiopulmonary resuscitation (CPR) performance is crucial for survival. There are differences between the performances of CPR in pediatric cases compared to CPR in adults. In all cases in which CPR is needed, there is a possibility for the occurrence of CPR-related traumatic injuries. Aims and methods: We used all available forensic examination methods in order to provide objective forensic investigation conclusions and feedback to clinicians. Results: We present an untypical case of head trauma with intracranial bleeding caused via CPR-related traumatic injury. Although it is not connected with the mechanism and genesis of death, it should be noted as being practically casuistic. The child had a severe congenital heart malformation. The surgical team decided that surgery was absolutely necessary. Complications developed in the postoperative period. On the second postoperative day, cardiac arrest occurred, CPR was performed, and the girl survived for 15 minuntil there was a second cardiac arrest. A second CPR was performed, but she died. During the forensic autopsy, with the exception of expected findings, head bruising and intracranial bleeding were registered. Conclusion: The forensic conclusion was that the head trauma was caused accidentally during CPR due to the non-voluntary impact of the head with respect to the background of anticoagulant therapy, which was one possible factor for the massive bleeding. Full article

During the early development of marine invertebrates, planktic larvae usually occur, and their body surfaces often form specific types of cilia that are involved in locomotion and feeding. The echiuran worm Urechis unicinctus sequentially undergoes the formation and disappearance of different types of body surface cilia during embryonic and larval development. The morphological characteristics and molecular mechanisms involved in the process remain unclear. In this study, we found that body surface cilia in U. unicinctus embryos and larvae can be distinguished into four types: body surface short cilia, apical tufts, circumoral cilia and telotrochs. Further, distribution and genesis of the body surface cilia were characterized using light microscope and electron microscope. To better understand the molecular mechanism during ciliogenesis, we revealed the embryonic and larval transcriptome profile of the key stages of ciliogenesis in U. unicinctus using RNA-Seq technology. A total of 29,158 differentially expressed genes (DEGs) were obtained from 24 cDNA libraries by RNA-Seq. KEGG pathway enrichment results showed that Notch, Wnt and Ca²⁺ signaling pathways were significantly enriched during the occurrence of apical tufts and circumoral cilia. Furthermore, all DEGs were classified according to their expression pattern, and DEGs with similar expression pattern were grouped into a module. All DEG co-expression modules were correlated with traits (body surface short cilia, apical tufts, circumoral cilia and telotrochs) by WGCNA, the results showed DEGs were divided into 13 modules by gene expression patterns and that the genes in No. 7, No. 8 and No. 10 modules were to be highly correlated with the occurrence of apical tufts, circumoral cilia and telotrochs. The top 10 hub genes in the above three modules were identified to be highly correlated with ciliogenesis, including the reported cilium-related gene Cnbd2 and unreported cilium-related candidate genes FAM181B, Capsl, Chst3, TMIE and Innexin. Notably, Innexin was included in the top10 hub genes of the two modules (No. 7 and No. 8), suggesting that Innexin may play an important role in U. unicinctus apical tufts, circumoral cilia and telotrochs genesis. This study revealed the characteristics of ciliogenesis on the body surface of U. unicinctus embryos and larvae, providing basic data for exploring the molecular mechanism of ciliogenesis on the body surface. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 19 (COVID-19). COVID-19 can manifest with a heterogenous spectrum of disease severity, from mild upper airways infection to severe interstitial pneumonia and devastating acute respiratory distress syndrome (ARDS). SARS-CoV-2 infection may induce an over activation of the immune system and the release of high concentrations of pro-inflammatory cytokines, leading to a “cytokine storm”, a recognized pathogenetic mechanism in the genesis of SARS-CoV-2-induced lung disease. This overproduction of inflammatory cytokines has been recognized as a poor prognostic factor, since it can lead to disease progression, organ failure, ARDS and death. Moreover, the immune system shows dysregulated activity, particularly through activated macrophages and T-helper cells and in the co-occurrent exhaustion of lymphocytes. We carried out a non-systematic literature review aimed at providing an overview of the current knowledge on the pathologic mechanisms played by the immune system and the inflammation in the genesis of SARS-CoV-2-induced lung disease. An overview on potential treatments for this harmful condition and for contrasting the “cytokine storm” has also been presented. Finally, a look at the experimented experimental vaccines against SARS-CoV-2 has been included. Full article