Chemical Index Research Articles

Spectrum-effect relationship between HPLC fingerprints and antioxidant activity of Qi-Fu-Yin based on multiple statistical correlation analysis.

Qi-Fu-Yin has been used to treat Alzheimer's disease (AD) in China. Oxidative stress has been recognized as a factor in AD progress. To date, there is no quality control method to ensure batch-to-batch consistency of Qi-Fu-Yin, and the potential antioxidant compounds in Qi-Fu-Yin remain uncertain. The aim of this study is to identify the potential antioxidant compounds of Qi-Fu-Yin and establish quality control standards for Qi-Fu-Yin. High-performance liquid chromatography was used to establish and quantify the fingerprints of Qi-Fu-Yin from various batches. Ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS) was used to identify the common peaks. Bivariate correlation analysis, partial least squares regression analysis, and gray correlation analysis were used to establish the spectrum-effect relationship. Forty-nine common peaks were determined through the establishment of fingerprints. Among them, 35 common peaks were preliminarily characterized. The multiple statistical correlation analysis methods identified six compounds as potential antioxidant constituents of Qi-Fu-Yin, and their antioxidant activities were validated in vitro. All six antioxidant compounds derived from two herbs. Therefore, three chemical index compounds derived from other three herbs were added to the quantitative analysis, while for two herbs, no peaks could be included. Eventually, six antioxidant constituents and three index compounds were quantitatively determined to provide a relatively comprehensive quality control for Qi-Fu-Yin. The study elucidated the antioxidant substance basis of Qi-Fu-Yin and provided a relatively comprehensive approach for the assay of Qi-Fu-Yin, which is a promising advance in the quality control of Qi-Fu-Yin.

Combined Aerobic Fermentation of Maricultural and Agricultural Solid Waste: Physicochemical Property and Bacterial Community Structure

The large-scale production of maricultural solid waste is not used effectively and has a significant impact on the environment. However, there is no report on the utilization of solid waste in mariculture of maricultural and agricultural solid waste. At present, aerobic composting is a simple and feasible means of waste resource utilization, but it also seriously pollutes the environment. This paper studied the change of physical and chemical properties (T1: solid waste + straw, T2: solid waste + cow dung + straw, T3: solid waste + cow dung + straw + 5% biochar, T4: solid waste + chicken dung + cow dung + straw + 5% biochar) and microbial succession in the composting process (T4: solid waste + chicken dung + cow dung + straw + 5% biochar) and the effect of decomposed products on seed growth. The results showed that the mixed compost of various materials had a good regulating effect on the physical and chemical indexes, and the highest temperature could reach 69.4 °C. Biochar could extend the high temperature period by 1–2 days. The germination indexes of seeds treated with T1–T4 were 75%, 80%, 81%, and 94%, respectively. Through the change of the seed germination index, it could be seen that the bacterial community structure changed significantly during composting. The Chao 1 index and Shannon index showed that the bacterial abundance and diversity index increased and then decreased. The analysis of the bacterial community structure showed that Proteobacteria and Acinetobacter were the main bacteria in composting, and the relative abundance of Proteobacteria was 81.9% at the phyla level. Acinetobacter and Pseudoxanthomonas were the main bacteria in the process of composting. Acinetobacter was the dominant bacteria in the heating stage, with an abundance of 67.2%.

Geochemistry of Mallampalli Group Phyllite from Pakhal Supergroup, Western Belt of Pakhal Basin in Pg Valley, Telangana: Implications for Provenance & Source Area Weathering

Phyllites from the Mallampalli group from the Pakhal Supergroup rocks of Pakhal Basin in PG Valley, Telangana,India was analyzed for their major and trace element geochemistry in order to constrain their provenance and source area weathering. The analyses of the phyllites generally define a single geochemical group by their major- and trace-element abundances. The metamorphosed sediments may be classified as immature by their high index of compositional variability values of mostly < 1. HREE are generally depleted whereas LREE are typically enriched relative to average Proterozoic upper crust. Such geochemical characteristics suggest that the source of the phyllites dominantly consisted of felsic rocks. Average Cr and Ni abundances and Cr/Ni ratios of average phyllites of the Mallampalli metasediments indicate that the source consisted of granitic material. Major element data, plotted in Al2O3 – (CaO+Na2O) – K2O ternary diagram indicate that the phyllites have not undergone significant post-depositional K metasomatism. Low to moderately high chemical weathering of the source terrane is indicated by pre metasomatized chemical index of alteration values of 60 – 86. The geochemical data further suggest that the sediments were deposited within a passive margin setting and mostly supplied by the adjacent basement granitoids.

GEOCHEMISTRY OF PAB SANDSTONE EXPOSED IN LAKI RANGE LOWER INDUS BASIN: PROVENANCE AND TECTONIC IMPLICATIONS

Geochemistry of the late Cretaceous Pab Sandstone deposited at the Laki Range, Southern Indus basin, was carried out in order to acquire a better knowledge of the source rock and paleoclimate. The unit in the studied region comprise predominantly sandstone, with some mudstone. The major element geochemistry of Pab Sandstone suggests that the samples were composed of abundant SiO2, Al2O3, CaO, and Fe2O3. Other major oxides comprises less than 2 wt. %. Major element discriminatory diagrams additionally imply that Pab sediments originated from a granitic source. The idea that the Pab sediments were generated by a granitic source is further supported by the rich concentration of trace elements including Zr, La Th, Ba, and Sr, in contrast to V, Ni, Cr, Co, and their ratio. It is conceivable that the Pab Sandstone was formed by sediments from granitic rocks, as indicated by the La/Sc and Th/Co model, as well as the TiO2 and Zr plots. The measured Plagioclase Index of Alteration (PIA) values, which range from 59.94 to 89.44, and the Chemical Index of Alteration (CIA), which ranges from 61.12 to 83.75, indicate that the studied sediments experienced moderate to strong weathering under warm, humid climate conditions. Geochemical findings indicate that the Pab Sandstone sediments originated from the vast Indian Shield (Craton); probably from the Malani Igneous Suite in India and the Nagar Parkar Igneous Complex in Pakistan.

Geochemical and depositional environment of an Upper Cretaceous greensand giant (Münsterland Cretaceous Basin, Germany)

Based on integrated geochemical, mineralogical and stratigraphic-sedimentological analyses of core section KB 4507/1001 Essen-Bedingrade from the Münsterland Cretaceous Basin (northern Germany), the geochemical and depositional environment of a Late Cretaceous greensand giant has been elucidated. The >100-m-thick Cretaceous succession comprises the Essen Greensand (Cenomanian), Büren (lower Turonian), Duisburg (middle Turonian to lower Coniacian) and Emscher formations (middle to upper Coniacian), essentially consisting of alternating greensand and marl lithofacies. X-ray diffraction analyses showed that the abundant green grains undoubtedly constitute glauconitic minerals with high-order, 1M-type layer stacking. The depositional environment can be characterized as a shallow-marine setting in which nearshore greensands interfingered with mid-shelf marls. Inorganic geochemical analyses normalized to Al and compared to average shale (AS) show that most element/Al (E/Al) ratios are higher than AS values, including the chemical index of alteration (CIX). This suggest that an intensely chemically weathered wet hinterland provided for a constant supply of essential elements required for nearshore glaucony authigenesis under variably reducing or oxidizing conditions and slightly increased palaeoproductivity. The leaching of paleosols and swamp-like coastal wetlands during transgressive phases related to eustatic early Late Cretaceous sea-level changes was an important source for trace metals and nutrients while the considerable influx of terrestrial organic matter suggests a significant input of K related to plant decay. In a nutshell, our new integrated data from the Münsterland Cretaceous Basin provide important novel insights into the formative processes of authigenic glauconitic minerals during warm-humid climate phases of Earth history.

Middle Ordovician climatic and oceanic destabilization in a slope-setting of the Yangtze platform, South China, and its role as a regional brake on the Ordovician radiations

During the Middle Ordovician, the Great Ordovician Biodiversification Event (GOBE) saw an accelerated diversification pulse in the marine metazoan richness, which has been linked to the oceanic and climatic changes. Here we have examined a deep-water slope succession, Xijinhe section, in Lower Yangtze region by integrating sedimentological and geochemical methods. This study highlights that the climatic and oceanic destabilization might have substantially impacted the marine biodiversity during the Middle Ordovician in South China. Three phases are identified based on lithological and geochemical variations. During Phase I across the Early–Middle Ordovician transition (Floian–Dapingian), the TOC and abundances of redox sensitive elements (RSE) are relatively depleted, suggesting a suboxic-oxic environment in the slope area of Yangtze Sea. The continental chemical weathering intensity transits from stable to unstable in Phase I indicated by CIA (chemical index of alteration) that gradually fluctuate to lower values, potentially caused by the secular cooling. The slowly ameliorating climate and redox conditions advanced the biodiversification across the Early–Middle Ordovician transition. During the Phase II in the Darriwilian, the continental chemical weathering intensity continues to decrease and the concentrations of RSE start to rise. The values of Mn(%)*Co(ppm) become consistently lower than 0.4, and the bio-limited elements such as P, Ba, and Ni are substantially enriched correspondingly. This phenomenon implicates that a secular cooling climate would have resulted in oceanic destabilization by improving upwelling of deeper anoxic/euxinic and eutrophic water into epicontinental sea, potentially causing a deceleration in the biodiversification during the Darriwilian in South China. The Phase III across the Middle–Late Ordovician transition, witnesses the continuous decrease of CIA values and highest abundances of TOC and RSE though some minor fluctuations, indicating a possibly even more drastic oceanic destabilization relative to Phase II. Deeper anoxic/euxinic water continuously intruded and shoaled into the shelf area during the Phase III due to the enhanced upwelling. Consequently, the habitat of marine organisms in shallow water was contracted, and becoming harsher. Additionally, bio-limited elements such as P were released from anoxic sediments and recycle into the seawater during the Middle Ordovician, boosting primary productivity level and may further deplete oxygen in seawater. This unstable oceanic state during the Middle Ordovician, particularly Darriwilian, represented by high nutrients content in epi-continental sea and expanding anoxic/euxinic water, could be attributable for the deceleration of biodiversification in South China and potentially the spatially variable paces of biodiversification in different paleo-continents during the main phase of the GOBE.

Analyzing polycyclic aromatic hydrocarbons using topological indices and QSPR analysis to reveal molecular complexity

Polycyclic aromatic hydrocarbons (PAHs) have distinctive chemical structures and are well known for their wide range of uses and environmental relevance. This work explores the impact of these structural characteristics on eccentricity-based topological indices offering information about the arrangement of atoms within the molecules. This study uses quantitative structure-property relationship (QSPR) analysis to construct prediction models for understanding and forecasting specific PAHs including Dibenzo[e,l]Pyrene, Heptacence, Heptaphene, Naphthacene, Naphthalene, Naphto[1,2a]pyrene, Naphtho[2,3a]pyrene, perylene, Perylene, Picene, Phenanthrene, Pyrene, Tetraphene, Tribenzo[b,n,pqr]perylene, Tribenzo[a,fg,op]tetracene and Triphenylene. Furthermore, regression analysis applies to clarify the quantitative correlations between the factors under study and improves the interpretability of the data produced. The combined use of these diverse approaches advances a thorough comprehension of the mutual influence of chemical structure, topological indices and predictive modeling about PAHs.

Source and Migration Pathways of Heavy Metals in Soils from an Iron Mine in Baotou City, China

The exploitation of iron ore could cause heavy metals pollution in the soils, which threatens the ecosystem and human health. In this study, soil, stream sediment, tailings, rock, and atmospheric deposition samples were collected from an iron mine in Baotou City. The concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, Al2O3, CaO, K2O, MgO, Na2O, SiO2, and Fe2O3, as well as the mineral composition and heavy metal speciation of the samples, were analyzed for pollution assessment and source identification of heavy metals. The results reveal that the concentration of Cu in the soils was significantly higher than the background value, and an unpolluted to moderately polluted state was the main pollution level. By analyzing the relationship between Cu/Al2O3 and CaO in different samples, as well as the characteristics of the chemical index of alteration (CIA), mineral composition, and the chemical speciation of Cu in soils and profiles, the results suggest that tailings were the source of Cu pollution in soils. The distribution characteristics of Cu and CaO in stream sediments indicated that hydraulic transport may be one of the main migration pathways. In addition, wind transport may also be a pathway of migration.

The influence of topography and transport history on the composition of clastic deposits from the Jurassic Tlaxiaco basin, southern Mexico: limitations on the use of mineral and chemical indices as proxies for paleoclimate

ABSTRACT The mineral and chemical composition of clastic deposits is commonly used as a proxy for reconstructing the climatic history of the Earth. A mineralogical and chemical study of clastic deposits from the Jurassic Tlaxiaco basin of southern Mexico illustrates that the entire sedimentary system in which detritus is generated, subaerially transported, and deposited exerts a major control on the composition of sedimentary rocks, placing some constraints on the use of mineral and chemical indices as paleoclimatic proxies. Since clastic deposits of the Tlaxiaco basin were formed under similar humid climatic conditions, but in sedimentary systems with different topography and transport histories, they represent a natural laboratory for testing the control that these parameters exert on the composition of clastic rocks. Our petrographic and chemical results show that, in sedimentary systems associated with low relief and in which detritus had the possibility of being temporarily stored in floodplains and meandering bars, parent rocks and the derivative detritus interacted with weathering fluids over a long time, producing clastic deposits with composition that is representative of the weathering conditions and climate of the region. On the other hand, in environments associated with steep and tectonically active relief, the rates of sediment transport and burial exceed the rate at which weathering can generate detritus, producing sedimentary deposits with composition that largely underestimates potential weathering and provide unreliable information on climate. Mineral and chemical indices should be considered as reliable paleoclimate proxies only when sedimentological data indicate that the sedimentary system allowed sediment interaction with weathering fluids over a long time.

A novel inherent safety index for reactive hazard evaluation integrating thermal and pressure effects

Chemical reactive hazard is one of the main causes for accidents in chemical production, inherent safety indexing methodology is considered the most effective method for reactive hazard evaluation. Traditional reactive inherent safety indices often neglect pressure-related risks in runaway scenarios. This work introduced a chemical reactive risk index (CRRI), filling the gap in pressure risk assessment. CRRI integrates a semi-quantitative method based on risk analysis principles, consisting of the probability of reaction runaway and the severity of its consequences. The consequence of the whole runaway process is evaluated, and the severity of thermal and pressure effects are considered comprehensively. The PVA, TBHP and PFA production processes are utilized as case studies to demonstrate the application process and evaluation effectiveness of CRRI. The results illustrate the superiority of CRRI in comprehensive assessment of reaction risks, indicating CRRI as a reliable safety assessment tool for chemical reactions, helping to select inherently safer reaction processes.

Effects of Aviation Mutagenesis on Soil Chemical Indexes, Enzyme Activities, and Metabolites of Dahongpao (Camellia sinensis) Tea Trees.

Aviation mutagenesis is a breeding method for the rapid selection of superior plant varieties. In this study, rhizosphere soil chemical indexes, soil enzyme activities, and soil metabolites were measured in Dahongpao tea trees with aviation mutagenesis (TM) and without aviation mutagenesis (CK). The main soil metabolites distinguishing TM and CK and their relationships with soil chemical indexes and soil enzyme activities were analyzed and obtained. The results showed that there was no significant change in the rhizosphere soils' pH of TM tea trees compared to CK (p = 0.91), while all other chemical indexes of TM were significantly higher than CK (p < 0.05). In addition, the activities of enzymes related to soil nutrient cycling such as urease, protease, sucrase, acid phosphatase and cellulase, and enzymes related to soil antioxidants such as superoxide dismutase, catalase, peroxidase, and polyphenol oxidase were significantly increased (p < 0.05) in the rhizosphere soils of TM tea trees compared to CK. Soil metabolite analysis showed that the main soil metabolites distinguishing CK from TM were carbohydrates, nitrogen compounds, and amines. Of these, carbohydrates and nitrogen compounds were significantly positively correlated with soil chemical indexes and soil enzymes, whereas amine was significantly negatively correlated with soil chemical indexes such as organic matter, total nitrogen, total potassium, available nitrogen, available phosphorus; amine showed significant negative correlation with soil enzymes such as catalase, peroxidase, polyphenol oxidase, and urease. It can be seen that aviation mutagenesis is conducive to improving the ability of tea tree rhizosphere aggregation and transformation of soil nutrients, increasing the total amount of soil nutrients and the content of available nutrients, which is more conducive to promoting the uptake of nutrients by the tea tree, and thus promoting the growth of the tea tree.

Changes in chemical weathering regime of shelf sediments of the East China Sea controlled by sea-level and climatic changes since the last deglaciation

Chemical weathering of shelf sediments is important in driving the global elemental cycle and climate to maintain the earth’s habitability. However, the response mechanism between chemical weathering of shelf sediments and climate and sea-level changes is still unclear. This study focuses on core ECMZ located in the mud area of the East China Sea (ECS) inner shelf. The results indicate that the mechanisms controlling chemical weathering in the sediment of the ECS inner shelf differ at different timescales. On the orbital time scale, the Chemical Index of Alteration (CIA) indicates that the intensity of chemical weathering in sediments during the deglacial period was significantly higher than that during the Holocene. This was caused by shelf exposure during low sea-level periods when the sediments were fully exposed and the residence time in the weathering zone was long, leading the shelf sediments to undergo consistent and complete weathering under supply-limited conditions. In comparison, during cold events on the millennium-centennial time scale, such as Younger Dryas, 8.2 ka, and 4.2 ka, chemical weathering was weaker (lower CIA values) due to accelerated erosion as a result of lower temperatures and higher precipitation, which shortened the rocks’ residence in the weathering zone, resulting in the control of chemical weathering shifted from supply factors to kinetic ones, such as temperature and precipitation. Our findings suggest that on the orbital time scale, glacial shelf exposure could enhance chemical weathering, thereby reducing atmospheric CO2; on the millennium-centennial time scale, chemical weathering could rapidly respond to abrupt climate events.

Effects of the fermentation quality and microbial community of waxy maize mixed with fodder soybean silage.

Waxy maize (Zea mays L. sinensis Kulesh) is highly regarded for its high nutritional content and unique taste. Although the stalks and leaves contain high carbohydrate levels after ear harvesting, inadequate crude protein (CP) limits the utilization and promotion of waxy maize silage in animal husbandry. In this study, waxy maize and fodder soybeans were mixed for sowing in different proportions [1:0 (CK), 1:1 (A1), 1:2 (A2), 1:3 (A3), and 1:4 (A4)] to investigate the effects of different mixing ratios on the growth of the waxy maize, the chemical indices, fermentation quality, and the microbial community of the mixed silage after ear harvesting. The mixed planting of waxy maize and fodder soybeans in different proportions had no effect on the yield and quality of the waxy maize ears and increased the aboveground biomass after ear harvesting. After ear harvesting, the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents significantly decreased, and the CP content and relative feeding value (RFV) gradually increased in the mixed silage. The pH of the treatments was lower than 4.2 except for A4, and the lowest ammonia nitrogen (AN) concentration was observed in A3. With increasing proportions of fodder soybeans, the abundance of beneficial bacteria increased and that of harmful bacteria decreased; Firmicutes and Lactobacillus were the dominant phylum and genus, respectively, and both increased gradually. Redundancy analysis (RDA) revealed that the fermentation indices affecting the microbial community composition in the silage were inconsistent among the different mixed sowing combinations. The Mantel test showed that the composition of the microbial communities in the treatments was significantly correlated with the ADF, water-soluble carbohydrate (WSC), and propionic acid (PA) contents. Comprehensive analysis revealed that the optimal mixed sowing ratio of waxy maize to fodder soybeans was 1:3, and waxy maize and fodder soybeans silage can increase the utilization of aboveground biomass and improve the fermentation quality and feeding quality of silage by changing the microbial community. These findings lay a certain theoretical foundation for improving the utilization of waxy maize.

The association between mixed exposure to per- and polyfluoroalkyl substances (PFAS) and the risk of diabetes

IntroductionThis study aims to investigate the relationship between exposure to per- and polyfluoroalkyl substances (PFAS) and the risk of diabetes by analyzing a large dataset from the National Health and Nutrition Examination Survey (NHANES).Material and methodsThis study analyzed data from the US NHANES database from 2003 to 2018. Generalized linear regression models were used to examine the relationship between serum chemical concentrations and diabetes. Weighted quantiles and regression were employed to assess the association between mixed chemical exposure and diabetes. The 'mixture effect' between chemicals and diabetes was estimated using a Quantile g-Computation model.ResultsThe study involved 11,780 participants, with 1,451 individuals having diabetes and 10,329 being non-diabetic. Logistic regression analysis was to investigate the relationship between five PFAS chemicals and the diabetes risk, while controlling for all covariates. The results indicated that none PFAS chemicals exhibited a statistically significant association with an increased risk of diabetes. However, when exploring the positive and negative constraint models of the Weighted Quantile Sum (WQS), the coefficient of the chemical mixing index displayed a strong correlation with diabetes in model III, even after adjusting for covariates. Additionally, an evaluation of the 'mixture effect' using Quantile g-computation revealed that among the five chemicals, the combined exposure effect of Perfluorononanoate (PFNA) on diabetes was positive, whereas exposure to the other four chemicals had a negative impact.ConclusionsThe study findings suggest a possible connection between PFAS and an increased risk of diabetes, particularly highlighting PFNA's positive correlation with the combined exposure effect on diabetes.

Analyzing a series of ligands against malaria through the application of molecular docking, molecular quantum similarity, and reactivity indices

Background The primary goal of this research is to underscore the significance of molecular docking in the context of malaria drug discovery. Molecular docking plays a crucial role in comprehending the interactions between prospective drugs and the target proteins found in Plasmodium parasites. The study delves into the docking interactions of various compounds, emphasizing the necessity of stabilizing the active site to formulate potent and selective drugs. Methods The research focuses on highlighting compound-specific interactions with residues, stressing the importance of stabilizing the active site to design drugs tailored to specific target proteins. Inhibiting the function of these target proteins disrupts the life cycle of the malaria parasite. Quantum Similarity Analysis, utilizing Overlap and Coulomb operators, is employed to identify electronic similarities. The resulting quantum similarity values guide subsequent chemical reactivity analysis. Global reactivity indices such as chemical potential, hardness, softness, and electrophilicity contribute to drug design by showcasing compound-specific indices that underscore the significance of stability and electrophilicity. Fukui functions are utilized to visualize regions for stabilization, providing insights crucial for potential malaria treatment. Results The enhancement of drug-target binding affinity is observed through stabilizing interactions in the active site. Understanding electrophilicity at the active site emerges as a critical factor in drug design and selectivity. The rational manipulation of electrophilic interactions holds promise for developing potent and selective drugs against malaria. Consequently, the integration of molecular docking, quantum similarity analysis, and chemical reactivity indices offers a comprehensive approach to malaria drug discovery. Conclusions The study identifies potential lead compounds, emphasizing the crucial role of stabilizing the active site. Additionally, it sheds light on electronic considerations vital for the design of effective and resistance-resistant drugs. The insights provided by Fukui functions into regions susceptible to -H bond formation make these compounds promising candidates for malaria treatment.

Geochemistry and mineralogy of beach sediments in the northern Gulf of Mexico, Tamaulipas state, Mexico: implication for provenance

Geochemical and mineralogical studies were performed in the La Pesca (LP) and Tesoro Altamira (TA) beach sediments, located in the Tamaulipas state, northern Gulf of Mexico. The main aim of this study is to infer the weathering history and provenance and to discriminate the tectonic environment of the beach sediments. The sediments are composed of quartz with small amounts of accessory minerals such as plagioclase, calcite, orthoclase, microcline, and zircon. Both beach sediments are classified as fine-grained and very well sorted, however LP has coarse skewed and leptokurtic sediments, whereas TA has fine-skewed and very leptokurtic sediments. The chemical index of weathering (CIW’) indicates intense weathering in the source area. The quartz grain microtextures in the LP and TA are classified into mechanical, chemical, and mechanical/chemical origin. Mechanical features such as fractures, pits, percussion marks, abrasion fatigue, and V-shaped marks favor high-energy littoral, fluvial, subaqueous-marine, and aeolian environments. The chemical features indicate solution pits and crystalline overgrowth, which suggests a silica saturated marine environment. The mechanical/chemical features display adhering particles and elongated depressions suggest formation in a sub-aqueous nearshore marine environment. Major and trace elements-based provenance discrimination diagrams indicate a felsic source derived from the Mesa Central (MC), Sierra Madre Oriental (SMOr) and Oaxaquia terranes. The major and trace element concentrations imply a passive margin setting for the northern Gulf of Mexico, which is consistent with the general geology.

Climates and sea-level controls on chemical weathering in the northern shelf of the Okhotsk Sea in the past 23 ka

The Okhotsk Sea, a subarctic marginal sea with a wide shelf and abundant weathering products, provides ample information about the chemical weathering in the geological past. However, insufficient investigation in the Okhotsk Sea, especially in its shelf, limits our knowledge of the intensity of chemical weathering in high-latitudes. In this study, high-resolution geochemical elements compositions of the core LV87-54-1 were measured to reveal the provenance change in the Northern Okhotsk Sea Shelf since the Last Glacial Maximum (LGM) and to discuss the influential factors of the deep-sea weathering records. The elemental ratios suggested that the sediment provenance remained stable during 23–11.4 ka, mainly transported from the Okhotsk-Chukotka volcanic belt; whereas the sediment input from the Kamchatka Peninsula to the study area has been enhanced since 11.4 ka. During 23–14 ka, the chemical index of alteration (CIA) was observed to align with climatic changes in the Northern Hemisphere. Synchronized climatic deterioration (i.e., cooling and drying) in the Northern Hemisphere mainly contributed to the reduced alteration of the sediments eroded from the Okhotsk-Chukotka volcanic belt. During 14–11.4 ka, the reworking of older weathered sediments caused by sea-level rise overwhelmed climates in controlling silicate weathering, resulting in an increased alteration of sediments. During the Holocene, the core sediment witnessed a lower weathering degree, compared to the LGM–Deglaciation. We attribute this to an increased sediment input from the Kamchatka Peninsula that supplied more weaker weathered sediments to the study area.

Upper Neogene climate change in northern Africa based on chemical weathering indices and clay mineralogy: a case study of southeastern Tunisia (Gulf of Gabès)

Upper Neogene climate change in northern Africa based on chemical weathering indices and clay mineralogy: a case study of southeastern Tunisia (Gulf of Gabès)

Climatic controls on water-mass chemistry in a Paleocene lacustrine setting, Subei Basin, eastern China

The Paleocene epoch was characterized by global climate fluctuations and major carbon-cycle perturbations. During the greenhouse climate that characterized the early Cenozoic, a short-lived late Paleocene global cooling event has been recognized from marine records. However, the response of the terrestrial system to this climate cooling event is poorly understood. Here, we present major- and trace-element analyses, iron speciation systematics, carbonate carbon isotope data, and mineralogical observations from lacustrine sediments in Member II of the Paleocene Funing Formation (E1f2), utilizing well-preserved drill core from the Subei Basin, eastern China. Both chemical (chemical index of alteration [CIA], Al/K ratios) and mineralogical (mineralogical index of alteration, clay/feldspar ratios) proxies yield consistent weathering and paleoclimatic interpretations, suggesting a transition from cool and arid climatic conditions to warmer and more humid climatic conditions. Correlation of carbon isotopes between the Subei Basin and deep-sea records implies that this terrestrial setting records the short-lived Paleocene climate cooling event. The combination of climate records and paleosalinity proxies (B/Ga and S/total organic carbon [TOC]) indicates a relatively high-salinity water column (brackish to saline) under cool and arid climatic conditions in the Subei Basin, suggesting that elevated salinity was likely produced via net-evaporative conditions, rather than marine incursions. A shift toward less saline brackish conditions up section reflects an increase in precipitation and freshwater runoff under warmer and more humid climatic conditions. Iron speciation and redox-sensitive trace-metal systematics reveal fluctuating redox conditions, from oxic through to anoxic ferruginous, but with the distinct development of better ventilated conditions as freshwater inputs increased under more humid conditions. Our findings demonstrate the sensitivity of terrestrial climate to the late Paleocene climate cooling event and further reveal the chemical response of a lacustrine setting to a cooling episode in a greenhouse world.

Antibacterial [Zn(nicotinamide)2Cl2] complex for the treatment of skin conditions: An experimental-theoretical study of physicochemical, microbiological and in silico pharmacokinetic properties

A dichlorobis(nicotinamide)zinc(II) complex, [Zn(nicotinamide)2Cl2], was crystallized through the slow evaporation method, and its vibrational, electronic, structural, and thermal properties have been characterized. Density functional theory (DFT) was used for the accurate analysis of intramolecular vibrational modes, obtaining chemical reactivity indices and comparative studies of geometric and electronic parameters, including solvation effects in methanol, ethanol, and water, as well as in vacuum. Additionally, the nature and strength of the bonds associated with the coordination sphere (Cl–Zn and N–Zn) were elucidated from the quantum theory of atoms in molecules and natural bond orbital analyses. Powder X-ray diffraction showed that the coordination compound belongs to a monoclinic symmetry with P21/a (C2h5) space group. Thermal analyses revealed that the material is stable up to 200 °C. From DFT calculations, the complex is chemically more stable in solvents compared to vacuum conditions, with the aqueous medium offering greater stability. The chemical stability was also analyzed by infrared and Raman spectroscopy, with the results showing spectral changes mainly for the vibrational spectra obtained in methanol, ethanol, and water against those obtained in vacuum. Biological experiments showed the complex antibacterial activity against Gram-positive and Gram-negative bacteria, mainly against the Cutibacterium acnes ATCC 6919 strain. A computational study of the absorption, distribution, metabolism, excretion (ADME), and drug-likeness were calculated to support the experimental data.