Search Results (7,650)

Dolostone is an important reservoir for hydrocarbons, and significant hydrocarbons have been produced in the Middle Permian Qixia Formation dolostone reservoirs in the southeastern Sichuan Basin. The origin and formation process of the dolomite reservoir in the research area are studied through thin-section, geochemical, and sedimentary cycle analyses and U-Pb geochronology. Three types of dolomites were identified, including stratiform fine-crystalline dolomite (D1), patchy fine-crystalline dolomite (D2), and saddle dolomite cement (SD). D1 and D2 exhibit a range of δ¹³C values from 3.39‰ to 4.21‰ and a range of δ¹⁸O values from −6.06‰ to −5.75‰, indicating a mild depletion of δ¹⁸O relative to coeval seawater while maintaining seawater-equivalent δ¹³C signatures. Their ⁸⁷Sr/⁸⁶Sr ratios and REE patterns indicate seawater-derived fluids for D1 and D2 (both test results showed a U-Pb age of ≈274 Ma) and hydrothermal origin for SD. Sedimentary cycle analysis found that the regression process in the fourth-order sequence is conducive to the formation of dolomite under the background of regression in the third-order sequence. Exposure of bioclastic shoals enabled evaporated seawater reflux, forming penecontemporaneous D1 in fluid-saturated settings. Selective dolomitization occurred in the bioturbation structure with good porosity and permeability, forming D2. In the burial stage, the hydrothermal fluid had a slight transformation on the dolomite and formed SD. This model highlights transgressive–regressive cycle controls on reservoir development, providing exploration criteria for analogous carbonate systems. Full article

Nutritional and cooling strategies to abate the negative effects of heat stress during the dry period have been used to improve the performance of dairy cattle. The objective of this study was to evaluate the effects of feeding an immunomodulatory supplement (OmniGen-AF^®, OMN) before, during, and after exposure to either heat stress or active cooling during the dry period on immune function and mammary development in dairy cows. During late lactation (at least 60 d before dry off), cows were provided with evaporative cooling systems (shade, fans, and soakers) and assigned to two groups: placebo (56 g/d of AB20^® top-dressed; CON) or OmniGen-AF^® (OMN, 56 g/d top-dressed). Cows were dried off ~46 d before the expected calving date and further split into evaporative cooling (shade, fans, and soakers; CL) or heat stress (only shade; HT) pens. Thus, after dry off, there were four treatment groups: heat stress with placebo (HT, n = 17), HT with OMN supplementation (HT + OMN, n = 19), CL with placebo (CL, n = 16), and CL with OMN supplementation (CL + OMN, n = 11). From a subset of cows (n = 6–8 per group), four blood samples were collected during the dry period (−43, −39, −32, and −21 d relative to calving) to evaluate neutrophil function and blood hematology. In addition, mammary biopsies (4–6 cows/treatment) were collected at −43, −39, −32, and −21 d relative to calving to evaluate mammary gland gene expression and histology, i.e., Tdt dUTP nick-end labeling (TUNEL) and Ki67. Genes related to autophagy, apoptosis, and cell proliferation were analyzed by qRT-PCR. Relative to CL, HT downregulated the expression of beclin-2 (BECN2) but upregulated the expression of beclin-1 (BECN1) on days −43 and −39 relative to calving, respectively. Also, relative to CL, HT upregulated the expression of BAX and FAS on day −39 relative to calving. These differences in gene expression were followed by HT cows having a lower total cell apoptosis rate during involution relative to CL cows. Further to these effects, HT leads to a lower alveoli number relative to CL cows. As in the CL treatment, OMN cows have a higher total cell apoptosis rate and alveoli number relative to CON cows. In addition, OMN cows have higher total cell proliferation relative to CON. Prolactin (PRL) and cortisol concentrations were evaluated during the dry period at days −45, −26, −3, and −1 relative to calving. Relative to CL, HT cows had higher PRL at day −45 but lower PRL on day −1 relative to calving, and a similar trend was observed for cortisol concentrations. In summary, HT impacts mammary gland gene expression, compromises mammary involution, reduces alveoli number, and alters hormone dynamics throughout the dry period. Following the same trends as the CL treatment, OMN increases mammary gland turnover by having a higher cell apoptosis and cell proliferation rate and lower connective tissue relative to CON cows. Full article

The hydrological response to meteorological drought is often nonlinear, due to physiographic features and human activities, necessitating methodologies that surpass simple drought indices. This study investigates whether drought propagation can be statistically modeled, identifies factors influencing the time lag between meteorological and hydrological droughts, and evaluates the most suitable temporal scales of drought indicators. Meteorological droughts were detected using Standardized Precipitation Index (SPI), while hydrological droughts were identified by the Adapted Threshold Level Method (ATLM), which balances available reservoir volume and the water demand, including withdrawals and evaporation losses. Castanhão, Banabuiú, and Orós reservoirs, in the State of Ceará, Brazil, were used to study drought events, across three aggregated time scales of 12, 24, and 36 months. The propagation time was determined using three indicators, corresponding to onset (Δb), peak (Δp), and conclusion (Δe) lags. Longer meteorological droughts were found to propagate more slowly to hydrological systems, with temporal lags following a consistent order of Δp > Δb > Δe. The combination of SPI-12 and ATLM-36 droughts provided the strongest and most consistent positive correlations (95% confidence level) between drought duration and all three lag markers. This combination offers a robust framework for modeling drought propagation dynamics and improving water resource management strategies. Full article

The Ulan Buh Desert represents a quintessential desert ecosystem in the arid northwest of China. As the key factor to maintain the stability of ecosystem, the chemical characteristics of groundwater and its water relationship with vegetation need to be further studied. Through field sampling, hydrochemical analysis, hydrogen and oxygen isotope testing and the Bayesian mixing model (MixSIAR), this study systematically analyzed the chemical characteristics of groundwater, spatial distribution and vegetation water sources in the study area. The results show that the groundwater is predominantly of the Cl⁻–SO₄²⁻ type, with total dissolved solids (TDS) ranging from 0.34 to 9.56 g/L (mean: 2.03 g/L), indicating medium to high salinity and significant spatial heterogeneity. These characteristics are jointly controlled by rock weathering, evaporative concentration, and ion exchange. Soil water isotopes exhibited vertical differentiation: the surface layer (0–20 cm) was significantly affected by evaporative fractionation (δD: −72‰ to −45‰; δ¹⁸O: −9.3‰ to −6.2‰), while deep soil water (60–80 cm) showed isotopic enrichment (δD: −29‰ to −58‰; δ¹⁸O: −6.8‰ to 0.9‰), closely matching groundwater isotopic signatures. Vegetation water use strategies demonstrated depth stratification: shallow-rooted plants such as Reaumuria soongorica and Kalidium foliatum relied primarily on shallow soil water (0–20 cm, >30% contribution), whereas deep-rooted plants such as Nitraria tangutorum and Ammopiptanthus mongolicus predominantly extracted water from the 40–80 cm soil layer (>30% contribution), with no direct dependence on groundwater. Full article

This present investigative work proceeds with the statistical study of the heat transfer coefficient (CTC) in the different flow transitions that are formed in a horizontal pipe with variation in the angles of inclination in a collector/evaporator component of a heat pump of solar assisted direct expansion (DX-SAHP) by using R600a refrigerant as working fluid in Quito - Ecuador. The dimensions of the collector/evaporator are 3.8 and 1000 mm inside diameter and length, respectively. To determine the results obtained, five practical tests are carried out with inclination angles of 10, 20, 30, 40 and 45°, with speeds or mass flows that vary between 203.24 and 222.28 kg·m⁻²·s⁻¹, the heat fluxes reached values between 200.58 and 507.23 W·m⁻². The correlations proposed by Kattan, Kundu, and Mohseni, and the experimental data were considered for the analysis of the effects of heat transfer on flow patterns. The results obtained from the investigation show that the maximum CTC is 6163.83 W·m⁻²·K⁻¹ with an inclination angle of 45°. Statistical analysis was performed considering the direction of Pearson presented results that for the angle of inclination of 10° a greater inverse direction of −0.316 is obtained. Full article

Background/objectives: Pharmaceutical cocrystals have emerged as a promising strategy to enhance the solubility and bioavailability of poorly water-soluble drugs. Indomethacin (IND), classified as a Biopharmaceutics Classification System (BCS) Class II drug, exhibits low solubility but high permeability. This study aims to develop a synthesis method, evaluate cocrystal solubility/stability and the physicochemical properties of the pure components, and describe cocrystal solubility using a mathematical model. Methods: Cocrystals were synthesized via solvent evaporation, using ethanol, methanol, and ethyl acetate. The pure components, IND and benzoic acid (AcBz) were dissolved in each solvent and maintained in a thermostabilizer for 24 h. Cocrystal formation was confirmed by UV-V spectroscopy, differential scanning calorimetry (DSC), and infrared (IR) spectroscopy. Results: The results showed that the solubility of the cocrystals decreased with increasing benzoic acid concentration. Mathematical modelling revealed that solubility can be expressed as the product of the solubilities of the individual components and the stability constant of the solution complex. Among the solvents tested, ethanol exhibited the highest solubility and equilibrium constant (K_eq) for IND–AcBz cocrystals, suggesting a greater molecular affinity and enhanced cocrystal formation. Conclusions: These findings demonstrate that the formation of the novel INDAcBz cocrystal significantly enhances Indomethacin solubility and thermodynamic stability. These results validate benzoic acid as an effective coformer and establish phase solubility diagrams (PSD) as predictive tools for rational cocrystal design, supporting the future development of optimized pharmaceutical formulations. Full article

As a key zero-carbon energy carrier, the accurate measurement of liquid hydrogen flow in its industrial chain is crucial. However, the ultra-low temperature, ultra-low density and other properties of liquid hydrogen can introduce calibration errors. To enhance the measurement accuracy and reliability of liquid hydrogen flow, this study investigates the heat and mass transfer within a 1 m³ non-vented storage tank during the calibration process of a liquid hydrogen flow standard device that integrates combined dynamic and static gravimetric methods. The vertical tank configuration was selected to minimize the vapor–liquid interface area, thereby suppressing boil-off gas generation and enhancing pressure stability, which is critical for measurement accuracy. Building upon research on cryogenic flow standard devices as well as tank experiments and simulations, this study employs computational fluid dynamics (CFD) with Fluent 2024 software to numerically simulate liquid hydrogen flow within a non-vented tank. The thermophysical properties of hydrogen, crucial for the accuracy of the phase-change simulation, were implemented using high-fidelity real-fluid data from the NIST Standard Reference Database, as the ideal gas law is invalid under the cryogenic conditions studied. Specifically, the Lee model was enhanced via User-Defined Functions (UDFs) to accurately simulate the key phase-change processes, involving coupled flash evaporation and condensation during liquid hydrogen refueling. The simulation results demonstrated good agreement with NASA experimental data. This study systematically examined the effects of key parameters, including inlet flow conditions and inlet liquid temperature, on the flow characteristics of liquid hydrogen entering the tank and the subsequent heat and mass transfer behavior within the tank. The results indicated that an increase in mass flow rate elevates tank pressure and reduces filling time. Conversely, a decrease in the inlet liquid hydrogen temperature significantly intensifies heat and mass transfer during the initial refueling stage. These findings provide important theoretical support for a deeper understanding of the complex physical mechanisms of liquid hydrogen flow calibration in non-vented tanks and for optimizing calibration accuracy. Full article

Background/Objectives: Physiologically based kinetics (PBK) modelling provides (internal) exposure concentrations. We used a PBK model parameterized exclusively with in silico and in vitro data in a bottom-up approach to predict the pharmacokinetics of oxybenzone, a UV filter, present in two formulations (for which dose-normalized C_max and AUC from clinical studies were different). Methods: Skin absorption data were used to refine chemical-specific dermal absorption parameters for oxybenzone in a lotion and spray. The Transdermal Compartmental Absorption and Transit (TCAT) model in GastroPlus^® 9.9 was used to estimate vehicle and skin layer diffusion and partitioning and then used to simulate systemic exposure. The model was validated according to the OECD 331 guideline. Results: PK profiles simulated for both formulations after single and repeated applications correlated with clinical data profiles (used only to validate our approach), with a deviation from the C_max and AUC of <2-fold. Sensitivity and uncertainty analyses indicated that most input parameters had a medium to high reliability, whereas only a few parameters related to dermal delivery had a low reliability: the partition coefficient between vehicle and water for spray and the diffusion coefficient in stratum corneum for lotion. In vitro skin absorption results suggested that absorption kinetics were not statistically different between the formulations; however, parameters such as vehicle evaporation time were different. The fine-tuned TCAT model containing the absorption data suggested that the variability in clinical data might be due to other factors, e.g., the small number of subjects. Conclusions: These results demonstrate how formulation-dependent absorption kinetics improve confidence in estimated exposure, thanks to the PBK model with its bottom-up approach for nonanimal-based safety assessments. Full article

The Cochin Backwater region in Southern India is one of the most dynamic estuaries, strongly influenced by seasonal river runoff and seawater intrusion. This study explores the relationship between monsoonal rains, salinity, and stable isotopic composition (δ¹⁸O and δ¹³C) to estimate the contribution of freshwater fluxes at different seasonal intervals for the Cochin Backwater (CBW) estuary. Seasonal variations in oxygen isotopes and salinity revealed distinct trends indicative of freshwater–seawater mixing dynamics. The comparison of Local and Global Meteoric Water Lines highlighted the occurrence of enriched isotope values during the Premonsoon season, showing significant evaporation effects. Carbon (C) isotopic analysis in dissolved inorganic matter (δ¹³C_DIC) at 17 stations during the Premonsoon season revealed spatially distinct carbon dynamics zones, influenced by various sources. These characteristic zones were categorized as Zone 1, dominated by seawater, exhibiting heavier δ¹³C_DIC values; Zone 2, showing significant contributions of lighter terrestrial δ¹³C; and Zone 3, reflecting inputs from regional and local paddy fields with a distinct C₃ isotopic signature (−25‰), modified by estuarine productivity. In addition, different advanced machine learning techniques were tested to improve analysis and prediction of seasonal variations in isotopic composition and salinity. Although the data were sufficiently robust for demonstrating the feasibility and advantages of ML in isotopic hydrology, further expansion of the dataset would be essential for improving the accuracy of models, especially for δ¹³C. The combination of these advanced machine learning models not only improved the predictive accuracy of seasonal freshwater fluxes but also provided a robust framework for understanding the estuarine ecosystem and could pave the way for better management and conservation strategies of the CBW estuarine system. Full article

Photovoltaic/Thermal (PV/T) technology efficiently harnesses solar energy by co-generating electricity and hot water. Unlike conventional PV systems, PV/T systems improve thermal utilization, cool PV modules, and prevent performance degradation caused by high temperatures. Among the various PV/T configurations, micro-channel heat pipe (MCHP) systems are prominent due to their ability to enhance heat transfer through the use of vacuum-filled, refrigerant-sealed MCHPs. This study explores how factors such as working fluid type, evaporation section heat flux, fill ratio, and condensation section length impact system performance. A 3D steady-state CFD model simulating phase-change heat transfer was developed to analyze thermal and electrical efficiencies. The results reveal that R134a outperforms acetone in heat transfer, with thermal resistance showing a significant decrease (from 0.5 °C·W⁻¹ at a 30% fill rate to 0.3 °C·W⁻¹ at a 70% fill rate) under varying heat source powers. The optimal fill ratio depends on the heat flux; for powers up to 70 W, the fill ratio ranges from 30% to 50%, while above 70 W, it shifts to 60–80%. Additionally, a longer condensation section reduces thermal resistance by up to 30% and enhances heat transfer efficiency, improving the overall system performance by 10%. These findings offer valuable insights into optimizing MCHP PV/T systems for increased efficiency. Full article

Volatile organic compound (VOC) monitoring is crucial for environmental safety and health, but conventional gas sensors often suffer from poor selectivity or lack spatial information. Here, we report a localized surface plasmon resonance (LSPR) gas sensor based on Au nano-urchins coated with a zeolitic imidazolate framework (ZIF-8) for both the quantitative detection and visualization of VOCs. Substrates were fabricated by immobilizing Au nano-urchins (~90 nm) on 3-aminopropyltriethoxysilane-modified glass and subsequently growing ZIF-8 crystals (~250 nm) for different durations. Scanning electron microscopy and optical analysis revealed that 90 min of ZIF-8 growth provided the optimal coverage and strongest plasmonic response. Using a spectrometer-based LSPR system, the optimized substrate exhibited clear, concentration-dependent responses to three representative VOCs, 2-pentanone, acetic acid, and ethyl acetate, over nine concentrations, with detection limits of 12.7, 14.5, and 36.3 ppm, respectively. Furthermore, a camera-based LSPR visualization platform enabled real-time imaging of gas plumes and evaporation-driven diffusion, with differential pseudo-color mapping providing intuitive spatial distributions and concentration dependence. These results demonstrate that ZIF-8-modified Au nano-urchin substrates enable sensitive and reproducible VOC detection and, importantly, transform plasmonic sensing into a visual modality, offering new opportunities for integrated LSPR–surface-enhanced Raman scattering dual-mode gas sensing in the future. Full article

This study presents a molecular dynamics (MD) investigation of water evaporation in copper nanochannels, with a focus on accurately modeling copper–water interactions through forcefield calibration. The TIP4P/2005 water model was coupled with the Modified Embedded Atom Method (MEAM) for copper, and the oxygen–copper Lennard–Jones (LJ) parameters were systematically tuned to match experimentally reported water contact angles (WCAs) on Cu (111) surfaces. Contact angles were extracted from simulation trajectories using a robust five-step protocol involving 2D kernel density estimation, adaptive thresholding, circle fitting, and mean squared error (MSE) validation. The optimized forcefield demonstrated strong agreement with experimental WCA values (50.2°–82.3°), enabling predictive control of wetting behavior by varying ε in the range 0.20–0.28 kcal/mol. Using this validated parameterization, we explored nanoscale evaporation in copper channels under varying thermal loads (300–600 K). The results reveal a clear temperature-dependent transition from interfacial-layer evaporation to bulk-phase vaporization, with evaporation onset and rate governed by the interplay between copper–water adhesion and thermal disruption of hydrogen bonding. These findings provide atomistically resolved insights into wetting and evaporation in metallic nanochannels, offering a calibrated framework for simulating phase-change heat transfer in advanced thermal management systems. Full article

The remediation of soils contaminated with heavy metals and radionuclides remains a significant environmental challenge. This study evaluated the phytoremediation potential of industrial hemp (Cannabis sativa L.) in soil collected from a historical evaporation dam, characterized by high levels of diverse metals, including Al, Cr, Fe, and radioactive elements (U, Th). Three treatments were applied: a control, a metal-spiked treatment (chelated with citric acid), and an NPK + spike treatment. A separate six-month greenhouse trial compared plants grown with and without NPK nutrients. Results demonstrated that the addition of a chelating agent significantly enhanced the bioavailability and subsequent uptake of key metals, including U, Se, and Pd. NPK fertilization combined with chelation resulted in the greatest plant biomass (≈4.5 g) and height (>18 cm), which correlated with higher total metal accumulation. Bioaccumulation factors (BAF > 1) were highest for B, Sr, Cd, and Bi, with values for Cd and U reaching 1.3 and 2.1, respectively. Foliar analysis revealed that leaves accumulated significantly higher metal concentrations than stems (e.g., Translocation Factor (TF) ~ 2.0 for Cd, Pb, and U), acting as the primary sink. This study concludes that hemp, particularly when assisted with chelating agents and adequate nutrition, is a highly effective candidate for the phytoremediation of multi-metal contaminated soils. The NPK + chelation strategy is the most promising for maximizing both biomass production and metal extraction efficiency. Full article

China’s Yangtze and Yellow River Basins exhibit divergent drought patterns, yet the underlying mechanisms driving these differences remain underexplored. This study compares their drought characteristics from 1961 to 2022 using the Standardized Precipitation Index, Standardized Precipitation Evapotranspiration Index, and Palmer Drought Severity Index, and identifies their drivers through attribution models and interpretable machine learning. Our results reveal two distinct paradigms: the Yangtze Basin is characterized by high-frequency, over 14% in all seasons, short-duration droughts, reflecting a rapid hydrological response, while the Yellow River Basin experiences low-frequency, long-duration events indicative of strong soil moisture memory. Quantitative attribution demonstrates that atmospheric evaporative demand (VPD) plays a significantly greater role in the Yellow River Basin, contributing over 20% to soil drought, far exceeding its 14.4% contribution in the Yangtze Basin. Furthermore, their large-scale drivers differ fundamentally: the Yangtze Basin responds primarily to the Atlantic Multidecadal Oscillation (AMO) and Arctic Oscillation (AO), whereas the Yellow River Basin is mainly influenced by solar activity and the El Niño-Southern Oscillation (ENSO). These findings reveal that Yangtze drought is primarily driven by precipitation deficits, while Yellow River drought is a composite phenomenon amplified by evaporative demand. This distinction underscores the need for basin-specific water management strategies. Full article

In semi-arid regions of Morocco, where the majority of water withdrawals are devoted to irrigation, optimizing irrigation practices in agriculture is a national priority in the face of recurring droughts and growing pressure on groundwater resources. However, the hydrological impacts of different drip-irrigation systems in the soil–plant–atmosphere continuum remain insufficiently understood. We monitored the stable isotope composition (δ²H, δ¹⁸O) across the two agricultural plots in Marrakech (Morocco) with surface drip and subsurface drip irrigation treatments for a complete hydrologic year (June 2022 to June 2023). Weekly to daily samples of rainfall, irrigation water, groundwater, and soil at various depths (5–50 cm) were sampled, and water from branch xylem was extracted using the cryogenic vacuum distillation method. We found that the subsurface irrigation treatment, which delivered water directly to the root zone, maintained narrow isotopic ranges in water of soils beyond 30 cm, as well as in branch xylem and leaf water. By contrast, surface irrigation treatment plots showed pronounced evaporative isotopic enrichment: summer topsoil water δ¹⁸O peaked at −1.1‰ (vs. −8.7‰ in subsurface irrigation treatment), and leaf water reached +13‰ (vs. +8‰ in subsurface). Despite this larger isotopic heterogeneity in surface irrigation site, branch xylem water δ¹⁸O remained within −6 to 2.5‰ across all soil depth, similar to subsurface irrigation treatment, which ranged between −5 and 0‰. This suggests that olive roots accessed soil water uniformly from the upper 50 cm under both irrigation treatments. Seasonal xylem isotopic enrichment in spring and midsummer mirrored shifts towards shallow, evaporatively altered soil water under surface irrigation, but not under the subsurface. The results suggest that subsurface drip irrigation can significantly improve drought resilience and water-use efficiency in the expanding olive sector of the Maghreb, while continuous isotope monitoring serves as a practical approach to enhance sustainable and adaptive water management in water-limited regions. Full article