Search Results (113,762)

Water-sediment regulation Scheme (WSRS) is a crucial artificial control method for water and sediment in the lower reaches of the Yellow River (YR). During this period, the impact of high flow discharge and high sediment concentration on the distribution and transport of heavy metals in the Yellow River warrants particular attention. This study analyzes heavy metals in water and suspended sediments across different phases of the WSRS. During the WSRS, the lower Yellow River showed decreased levels of dissolved heavy metals. Evaluations of the ecological risk posed by Cd, Cu, Ni, Pb, Zn, and Cr in suspended sediments suggested an absence of risk or minimal risk levels. A greater percentage of Cd and Pb was found in bioavailable forms. And RAC analysis further revealed that Cd poses a relatively higher migration risk. Compared to the water regulation stage (WRS), the sediment regulation stage (SRS) was characterized by lower dissolved heavy metal concentrations but higher particulate heavy metal contents. Over 85% of heavy metals were transported by SPM in WSRS. During the sediment regulation phase, the mean particulate transport proportion for heavy metals surpassed 96%. This phase accounted for more than 50% of the total heavy metal flux delivered to the sea throughout the entire regulation period. These findings offer valuable insights into controlling and managing heavy metal risks during WSRS in the YR. Full article

The increasing occurrence of extreme rainfall events often leads to flash floods, infrastructure damage, loss of human life, and significant economic impacts. There is a pressing need for data-driven assessments and the application of robust analytical approaches to better understand these changes. Analyzing ground-level daily rainfall data from 1985 to 2023 from 26 monitoring stations, this study first employs the Mann–Kendall test using robust statistics including minimum, median, various quartiles, and maximum rainfall values for detecting long-term trends across Saudi Arabia. Next, the k-means clustering technique is applied to characterize the annual rainfall cycles across different regions of the country. Finally, the Peaks Over Threshold (POT) approach within Extreme Value Theory (EVT) is employed to identify site-specific thresholds for extreme rainfall using the Generalized Pareto Distribution (GPD). This automated, data-driven method offers a more objective alternative to the commonly used ad hoc percentile-based threshold selection, thereby enhancing the rigour and reproducibility of extreme rainfall analysis. Local specific thresholds were computed ranging from about 16 to 47 mm from Arar and Jazan, respectively. These thresholds were then used to calculate the frequency and intensity of extreme rainfall events. The fitted GPD parameters were further used to estimate return levels (RLs) for different return periods (2-, 5-, 10-, 20-, 50-, and 100-year) into the future. The results underscore considerable spatial variability in extreme rainfall behaviour across Saudi Arabia, with a higher likelihood of intense and infrequent precipitation events in the coming decades. Full article

An unmanned aerial vehicle (UAV) multi-spectral system provides a monitoring platform to rapidly obtain crop spectral information that can reflect crop nitrogen status for the generation of dynamic variable-rate nitrogen (VRN). To improve the accuracy of VRN prescription maps, a method of generating VRN prescription maps on the basis of the vegetation index was proposed, and the effects of UAV flight time and altitude on VRN prescription maps were analyzed. The experimental site was located in Dacaozhuang, Hebei Province, China, and the experimental crop was winter wheat (Lunxuan 145). The flight altitudes of the UAV system were set to 50, 70 and 90 m. The flight times were set to 8:00 a.m., 11:00 a.m., 2:00 p.m. and 5:00 p.m. local time. The flight area was 1.18 ha with a 60° rotation angle under a three-span center pivot irrigation system with an overhang. UAV flight missions were executed during the jointing, heading, and grain filling phases of winter wheat. There were 90 management zones with pie shapes in total, which were composed of a 10° angle in the rotation direction and 4 sprinklers along the lateral direction. The vegetation indices (VIs) which are closely related to crop nutrient status were selected and used to generate distribution maps, which were superimposed with the management zones to generate VRN prescription maps. The results demonstrated that the red-edge soil adjusted vegetation index (RESAVI) was relatively more sensitive to the nitrogen status of winter wheat than the other VIs were. The RESAVI distributions were stable during periods with a solar elevation angle greater than 50° (11:00 a.m.–2:00 p.m. local time), and the VRN prescription maps were similar, with the overlap percentage of the same fertilization grade being greater than 80% and the relative error of the fertilization amount being less than 5%. Compared with that at 2:00 p.m., the overlap percentage of the same fertilization grade was 56.6% in both seasons at 8:00 a.m., whereas flights at 5:00 p.m. exhibited overlaps of 70.9% and 44.6% in the 2023 and 2024 seasons, respectively. Conversely, the flight altitude had little influence on the fertilizer amount and VRN prescription maps. The difference in the amount of fertilizer used was less than 3% at different flight altitudes. The required time is half of that for a 50 m flight when the flight altitude is 70 m and one third of that when the flight altitude is 90 m. Our study recommended operating the UAV multi-spectral system at solar elevation angles greater than 50° when generating VRN prescription maps of winter wheat, and the flight height can be adjusted according to the field area and the endurance time of the UAV. Full article

Integrated additional cooling channels offer precise thermal management for solid-oxide fuel cells (SOFCs), mitigating temperature gradients. This research studies the thermal–hydraulic performance of cooling channels integrated between SOFC interconnectors, including a Diamond-type triply periodic minimal surface (TPMS), a conventional topology-optimized structure, and a topology-optimized lattice-filled structure. A conjugate heat transfer analysis is employed to investigate the influences of flow rate within the range of Reynolds numbers from 300 to 5000, and the effects of coolant type, including air and liquid metals, as well as the impacts of structural material. The results demonstrate that the topology-optimized lattice-filled structure, generating high turbulence mixing, achieves superior temperature uniformity, especially at high flow rates, despite having higher thermal resistance and pressure loss than the conventional topology-optimized design. The coolant types show the largest influence on thermal–hydraulic performance, and the use of liquid gallium in the conventional optimized design obtains the best temperature uniformity, yielding differences between the maximum and minimum temperatures of less than 5 K. Moreover, the higher-thermal-conductivity material improves temperature uniformity, even at low flow rates. Overall, the optimized-baffle designs in the conventional topology-optimized model, utilizing high-conductivity coolant and structural materials, could be the most suitable for thermal management of the SOFC. Full article

Saltwater Intrusion (SWI) is threatening coastal archaeological sites, particularly in Crotone, southern Italy. The study area has been experiencing notable SWI due to over-pumping of groundwater, rising land subsidence, and climate change. Consequently, this study examines the applicability of polycaprolactone (PCL), a common biodegradable polymer, as a protective barrier for archaeological conservation. PCL films were synthesized via solvent casting and dried under controlled conditions. Physicochemical properties of the films were evaluated using six analytical techniques: (1) contact angle measurements for surface hydrophobicity, (2) Fourier-Transform Infrared Spectroscopy (FTIR) for chemical stability, (3) Scanning Electron Microscopy (SEM) for morphological characterization, (4) permeability testing for evaluating saltwater diffusion, (5) mechanical testing for tensile properties, and (6) biodegradability assays for degradation rates. All samples were evaluated at 0, 30, 60, and 90 days in natural seawater. Results from these tests indicate that unmodified PCL films exhibited moderate hydrophobicity, partial hydrolytic degradation, resistance to permeability, declining mechanical strength, and limited biodegradability over the testing period. Full article

Depression affects millions of people worldwide. Traditional management relies heavily on periodic clinical assessments and self-reports, which lack real-time responsiveness and personalization. Despite numerous research prototypes exploring Internet of Things (IoT)-based mental health support, almost none have translated into practical, mainstream solutions. This gap stems from several interrelated challenges, including the absence of robust, flexible, and safe architectural frameworks; the diversity of IoT device ownership; the need for further research across many aspects of technology-based depression support; highly individualized user needs; and ongoing concerns regarding safety and personalization. We aim to develop a reference architecture for IoT-based safe and personalized depression management. We introduce IoTMindCare, integrating current best practices while maintaining the flexibility required to incorporate future research and technology innovations. A structured review of contemporary IoT-based solutions for depression management is used to establish their strengths, limitations, and gaps. Then, following the Attribute-Driven Design (ADD) method, we design IoTMindCare. The Architecture Trade-off Analysis Method (ATAM) is used to evaluate the proposed reference architecture. The proposed reference architecture features a modular, layered logical view design with cross-layer interactions, incorporating expert input to define system components, data flows, and user requirements. Personalization features, including continuous, context-aware feedback and safety-related mechanisms, were designed based on the needs of stakeholders, primarily users and caregivers, throughout the system architecture. ATAM evaluation shows that IoTMindCare supports safety and personalization significantly better than current designs. This work provides a flexible, safe, and extensible architectural foundation for IoT-based depression management systems, enabling the construction of optimal solutions that integrate the most effective current research and technology while remaining adaptable to future advancements. IoTMindCare provides a unifying, aggregation-style reference architecture that consolidates design principles and operational lessons from multiple prior IoT mental-health solutions, enabling these systems to be instantiated, compared, and extended rather than directly competing with any single implementation. Full article

Phalaenopsis orchids are globally significant high-value ornamental flowers due to their strange flower shape, gorgeous color, and long flowering period. The successful implementation of reflowering technology is expected to double the economic value of the Phalaenopsis industry. This study selected the cultivated variety Phalaenopsis ‘Hatuyuki’ as the material to investigate the effects of exogenous gibberellin A₃ (GA₃) application (0, 50, 100, 150, and 200 mg/L) on its reflowering. Growth phenotype analysis indicates that exogenous GA₃ significantly promotes the occurrence of reflowering in Phalaenopsis ‘Hatuyuki’ after the first flowering, specifically manifested in elongated leaves, flower bud differentiation, flower stalk growth, and an earlier onset of flowering. The application of exogenous GA₃ significantly enhances the accumulation of starch, soluble sugars, and proteins in Phalaenopsis ‘Hatuyuki’, while inhibiting the synthesis of free fatty acids. Gibberellins (GA₃, gibberellin A₁ (GA₁), and gibberellin A₈ (GA₈)), cytokinins (6-Benzyladenosine (BAPR) and Kinetin (K)), and indole-3-acetic acids (IAAs) (tryptamine (TRA), indole-3-acetic acid (IAA)) are the core endogenous hormones responding to exogenous GA₃ spraying treatment. Transcriptome analysis identified a total of 3891 differentially expressed genes (DEGs). The KEGG enrichment analysis revealed that the most significantly enriched KEGG pathways included ‘Plant hormone signal transduction’. Key genes involved in the plant hormone signal transduction pathway (AUX, IAA, SAUR, DELLA, MYC2) were validated through qRT-PCR, suggesting that these genes may be crucial for the exogenous GA₃ application that promotes the reflowering of Phalaenopsis ‘Hatuyuki’. Additionally, this study highlights 202 core DEGs responsive to exogenous GA₃. Combined with the analysis of hormone signaling pathways, it provides a new perspective for uncovering the key molecular modules involved in GA₃-regulated reflowering of Phalaenopsis ‘Hatuyuki’. Overall, the findings of this study indicate that exogenous GA₃ application can promote the re-flowering of Phalaenopsis ‘Hatuyuki’. Full article

Phase change materials (PCMs) integrated into building envelopes can store and release latent heat, reducing indoor temperature fluctuations and shifting thermal peaks. This study quantifies the time lag and comfort impact of PCM plaster under free-running conditions using two identical, instrumented model houses in Bácsalmás, Hungary. One house served as a reference, while the other was retrofitted with interior PCM plaster panels on four walls (51.2 kg paraffin, ≈8.12 MJ latent heat capacity). The temperatures of the walls, indoor air, and outdoor environment were monitored every five minutes for 105 spring/summer days. Daily peak times were extracted using moving-average smoothing, and time lags between exterior and interior wall peaks were computed. The PCM house exhibited roughly double the average lag compared with the reference (≈200 vs. ≈100 min), with lag distributions well described by lognormal fits. Comfort evaluation based on exceeded degree-hours (EDH) relative to the adaptive comfort range (EN 16798-1) revealed that larger peak-time lags correlated with lower overheating. Results confirm that PCM plaster significantly delays and attenuates daily temperature peaks, extends comfort periods, and supports passive strategies such as night ventilation and demand-side load shifting in lightweight buildings. Full article

As global climate change intensifies, hydrological processes in arid inland river basins are undergoing profound transformations, posing severe challenges to regional water security and ecological stability. This study aims to develop a coupled SWAT-LSTM model integrating glacier melt processes to simulate runoff dynamics in the Keria River basin under climate change, providing a basis for local water resource management. Based on natural monthly runoff observations from the Langgan hydrological station (1961–2015), glacier data extracted from Landsat 8 remote sensing imagery (2013–2019), and downscaled data from the CMIP6 Multi-Model Ensemble (MME), this study constructed a SWAT-LSTM coupled model to simulate future scenarios (2026–2100). Research indicates that this hybrid model significantly enhances the accuracy of hydrological simulations in high-altitude glacier-fed catchments. The Nash efficiency coefficient (NSE) during the validation period reached 0.847, representing a 15% improvement over the SWAT model. SSP5-8.5 is identified as a high-risk scenario, underscoring the urgency of emissions reduction; SSP1-2.6 represents the most desirable pathway, with its relatively stable pattern offering sustained advantages for long-term water resource management in the basin. The study further reveals a negative feedback mechanism between glacier ablation and runoff increase, validating the regulatory role of Jiyin Reservoir’s “store during floods to compensate for droughts” operation strategy in balancing basin water resources. This study explores the coupling path between the physical model and the deep learning model, and provides an effective integration scheme for the hydrological simulation of the global watershed with ice–snow meltwater as the main recharge runoff, especially for the adaptive management of water resources in inland river basins in arid areas. Full article

Salinization in the western Songnen Plain has limited regional ecology and land use for decades, with its primary cause closely tied to sediment transport. To elucidate sediment evolution and its role in soil salinization, a borehole from saline-alkali land in Taonan County, west of the Songnen Plain, was investigated within an AMS¹⁴C, OSL, and ESR dating framework. Grain size analysis, end-member modeling, and major-element geochemistry revealed four transport components—fluvial, aeolian, glacio-fluvial, and lacustrine. Five provenance stages from the late Early Pleistocene to the Early Holocene were found: (1) distal weathered volcanic rock transport with minor fluvial–alluvial input; (2) proximal alluvial–proluvial transport; (3) ice meltwater and wind-driven transport; (4) predominantly wind transport; and (5) renewed fluvial–proluvial transport. These shifts correspond to regional paleoclimate fluctuations driven by global ice volume cycles, which control sediment supply, hydrology, and consequently salt accumulation in warm humid periods and upward salt migration in cold dry periods. The findings of this study demonstrate that Pleistocene glacial–interglacial climate cycles are the dominant driver of sediment transport and salinization dynamics on the western Songnen Plain. Full article

Free-ranging hens are at risk of infection by parasites characterized by certain stages that develop in the soil until attaining the infective phase. To analyze the usefulness of a biological control strategy of helminths affecting pasturing hens, fecal samples containing eggs of the helminths Ascaridia galli and Capillaria spp. were collected and then homogenized with an electric mixer. A total of 64 small areas were established by placing wooden frames (15 × 40 × 30 cm) on the ground and then adding approximately 100 g of a fecal mixture (per area). Four batches of 16 areas were considered: G1, sprayed with 2 × 10⁶ spores of the parasitophagous fungus Mucor circinelloides (day 0) at 0.5 L/m² (=600 mL/area); G2, sprayed with spores twice (every two weeks); G3, sprayed four times (every week); and Control, sprayed weekly with water. After a four-week period, the egg viability reduced for ascarids and capillarids (26% and 27%, respectively) in the control group; 64% and 79% in G1; 71% and 82% in G2; and 79% and 80% in G3. It was concluded that spraying with fungal spores provides a very useful tool for preventing infection by helminths on free-range poultry. Full article

The COVID-19 pandemic was responsible for an unprecedented increase in psychological problems among post-secondary students worldwide. Drawing on data from a repeated cross-sectional (RCS) project, this study investigated changes in psychological symptoms, emotional regulation (cognitive reappraisal and emotional suppression), and academic, social, and personal–emotional college adjustment, and associations between these variables among students in two countries during the phases of lockdown (2021), lifting of restrictions (2022), and the endemic phase (2023). University students in Canada (n = 1014) and Spain (n = 447) completed online surveys during these periods. Students in both countries reported significant declines in perceived COVID-19 stress across the pandemic phases. In comparison with pre-pandemic rates, elevated psychological symptoms remained constant. There were some country differences, but sex differences were consistent. Psychological symptoms mediated the association between cognitive reappraisal and the adjustment measures among Canadian students during each pandemic period. Alternatively, they mediated the linkages of maladaptive emotional suppression with academic, social, and personal–emotional functioning of Spanish students at every phase, but only during the lifting of restrictions and the endemic phase for Canadian students. The results indicate the complexity of country and context in the role of emotional regulation during uncontrollable conditions and provide directions for intervention in stressful situations, including adjustment to university and future disastrous environmental events. Full article

The article presents a numerical model of a high-temperature superconducting (HTS) transformer rated at 13.8 kVA, equipped with windings made of 2G ReBCO tapes. The model was developed to analyze the coupled electromagnetic and thermal phenomena occurring during the inrush current period of transformer energization. It describes the dynamic processes of critical current exceedance, resistive zone formation, and local temperature rise within the superconducting tape structure under realistic operating conditions. The geometry of the ReBCO tape is represented with its active superconducting layer and metallic stabilizer layers. Temperature-dependent material properties of each layer, such as electrical resistivity, thermal conductivity, and specific heat capacity, are incorporated into the model. This approach enables a detailed analysis of the temperature distribution across all layers of the superconducting tape. The results indicate that the highest thermal stress occurs during the first inrush current peak, whose amplitude exceeds the critical current of the winding. At this stage, a distinct temperature rise is observed in the stabilizer layers, followed by gradual cooling in subsequent cycles of operation. The simulated current and temperature waveforms show good agreement with experimental measurements performed on a liquid-nitrogen-cooled transformer prototype. The developed model enables quantitative evaluation of local overheating risks, analysis of Joule loss distribution, and assessment of the influence of supply parameters and circuit impedance on the thermal stability of the system. Its application supports the optimization of HTS transformer design and provides valuable insight into the reliability of superconducting windings under transient inrush current conditions. Full article

This study aimed to investigate the effects of dietary guanidinoacetic acid (GAA) supplementation on yak physiology by evaluating growth performance, serum biochemical indices and plasm metabolomic profiles to elucidate the underlying regulatory mechanisms. Twenty-four male yaks (4–5 years; 249.38 ± 11.69 kg BW) were randomly allocated to three dietary treatments (n = 8): CON (basal diet), GAA1 (basal diet + 0.055% GAA), and GAA2 (basal diet + 0.11% GAA), with 55:45 of concentrate:roughage (DM basis). After a 10-day adaptation period, the feeding trial lasted 90 days. Body weights were measured on days 0 and 90 for growth performance evaluation, with blood samples collected on the final day for separation into serum and plasma to assess serum metabolic and antioxidant parameters and for plasma metabolomic profiling. The result showed that growth performance parameters displayed a positive trend, with average daily gain (ADG) showing marginal improvement (p = 0.072). Serum biochemical analysis revealed that dietary supplementation of GAA had no effect on serum biochemical parameters while tendency decreased GSH-Px activity (p = 0.087). Non-targeted metabolomics identified 39–121 differentially abundant metabolites in plasma across treatment groups. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of these metabolites revealed pathways such as tryptophan metabolism, glycerophospholipid metabolism, and arginine metabolism. Among the differentially abundant metabolites, N(omega)-Hydroxyarginine and tryptophan metabolites such as 5-hydroxytryptophan and serotonin were specifically highlighted. In conclusion, dietary supplementation of GAA in yaks has been confirmed to improve ADG, with a 0.11% supplementation level being more effective, and this may be associated with GAA enhancing amino acid metabolism, particularly arginine and tryptophan metabolism. Full article

This study examines herding behavior in six MENA stock markets, with a focus on the impact of geopolitical risks and downward/upward market conditions during COVID-19/non-COVID-19 periods. Empirical results reveal significant differences among MENA countries regarding herding behavior and the impact of geopolitical events. We conclude that herding was more pronounced during the COVID-19 pandemic, especially during downward markets. Additionally, we found that geopolitical risks further amplified herding during dramatic market periods, particularly at lower quantiles. An exception was the Saudi stock market, which exhibited resilience to geopolitical risks, likely due to strong government support and robust policies. In contrast, Lebanon’s stock market has been exposed to an increased herding due to political instability. These findings suggest that regulators should enhance mechanisms to monitor market activities and introduce efficient policies to mitigate systematic risk and strengthen financial stability during downturns. Full article