Search Results (264)

Taconis oscillations represent spontaneous excitation of acoustic modes in tubes with large temperature gradients in cryogenic systems. In this study, Taconis oscillations in hydrogen and helium systems are enhanced with a porous material resulting in a standing-wave thermoacoustic engine. A theoretical model is developed using the thermoacoustic software DeltaEC, version v6.4b2.7, to predict system performance, and an experimental apparatus is constructed for engine characterization. The low-amplitude thermoacoustic model predicts the pressure amplitude, frequency, and temperature gradient required for excitation of the standing-wave system. Experimental measurements, including the onset temperature ratio, acoustic pressure amplitudes, and frequencies, are recorded for different stack materials and geometries. The findings indicate that, independent of stack, hydrogen systems excite at smaller temperature differentials than helium (because of different properties such as lower viscosity for hydrogen), and the stack geometry and material affect the onset temperature ratio. However, pressure amplitude in the excited states varies minimally. Initial measurements are also conducted in a cooling setup with an added regenerator. The configuration with stainless-steel mesh screens produces a small cryogenic refrigeration effect with a decrease in temperature of about 1 K. The reported characterization of a Taconis-based thermoacoustic engine can be useful for the development of novel thermal management systems for cryogenic storage vessels, including refrigeration and pressurization. Full article

The rapid urbanization process has accelerated the degradation of ecosystem services (ESs) in peri-urban rural areas of the Yangtze River Delta (YRD), leading to increasing landscape ecological risks (LERs). Establishing a scientifically grounded landscape ecological risk assessment (LERA) system and corresponding control strategies is therefore imperative. Using rural areas of Jiangning District, Nanjing as a case study, this research proposes an optimized dual-dimensional coupling assessment framework that integrates ecosystem service value (ESV) and ecological risk probability. The spatiotemporal evolution of LER in 2000, 2010, and 2020 and its key driving factors were further studied by using spatial autocorrelation analysis and geodetector methods. The results show the following: (1) From 2000 to 2020, cultivated land remained dominant, but its proportion decreased by 10.87%, while construction land increased by 26.52%, with minimal changes in other land use types. (2) The total ESV increased by CNY 1.67 × 10⁹, with regulating services accounting for over 82%, among which water bodies contributed the most. (3) LER showed an overall increasing trend, with medium- to highest-risk areas expanding by 55.37%, lowest-risk areas increasing by 10.10%, and lower-risk areas decreasing by 65.48%. (4) Key driving factors include landscape vulnerability, vegetation coverage, and ecological land connectivity, with the influence of distance to road becoming increasingly significant. This study reveals the spatiotemporal evolution characteristics of LER in typical peri-urban villages. Based on the LERA results, combined with terrain features and ecological pressure intensity, the study area was divided into three ecological management zones: ecological conservation, ecological restoration, and ecological enhancement. Corresponding zoning strategies were proposed to guide rural ecological governance and support regional sustainable development. Full article

Mental health disorders, particularly depression and anxiety, have become increasingly prevalent among elite athletes, exacerbated by factors such as competitive pressure and the Coronavirus Disease 19 (COVID-19) pandemic. This study analyzes trends in the use of antidepressants, anxiolytics, and cannabinoids (delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD)) among Italian athletes from 2011 to the first half of 2023 (FH2023), referring to anti-doping reports published by the Italian Ministry of Health. Data from 13,079 athletes were examined, with a focus on non-prohibited medications, banned substances, and regulatory impacts, including threshold adjustments for THC since 2013 and the legalization of CBD. The results show fluctuating use of antidepressants/anxiolytics, with peaks in 2021 and the FH2023, coinciding with post-pandemic awareness. Positive THC cases rose following regulatory changes, reflecting socio-cultural trends. Gender disparities emerged, with THC use predominantly among males (e.g., nine males vs. one female in 2013), though female athletes were underrepresented in testing. This study highlights the need for personalized, evidence-based strategies that balance therapeutic efficacy and anti-doping compliance. Clinicians should carefully consider prescribing selective serotonin reuptake inhibitors (SSRIs) and benzodiazepines to address depression and anxiety and should monitor the risks of CBD contamination. Future research should adopt longitudinal, gender-sensitive approaches to refining guidelines and combating stigma in professional sports. Full article

Amid declining fish diversity and human pressures in freshwater ecosystems, robust basin-scale assessments are vital for effective fisheries management. This study collated nearly four decades of fishery yields from the Pearl and Yangtze Rivers to identify conservation priorities in the Pearl River Basin. It introduced a novel cumulative effect indicator based on zeta diversity—a biodiversity pattern metric—integrated with cumulative effects analysis for management decision-making. The research employed a multi-site generalized dissimilarity model to examine the non-linear relationships between fish species composition (ζ_n) and human pressures, environmental factors, and geospatial variations across elevation gradients. The cumulative effect indicator, reflecting responses to anthropogenic stress when assessing ζ₂ (related to β diversity), helped evaluate basins for conservation or restoration needs based on their unique or homogenized biotic communities. The results suggest that ζ diversity in low-elevation sub-basins has a stronger filtering effect on ζ by human pressures than in mid- to high-elevation sub-basins, where community aggregation is more random. The impact varied with diversity aspects (nestedness vs. turnover) and zeta order. A negative correlation between cumulative effects and community uniqueness validated the novel cumulative effect indicator’s effectiveness for guiding restoration in the Pearl River Delta, potential fishing bans, and karst conservation. This approach offers a theoretical basis for prioritizing areas for freshwater fish diversity conservation and fishing restrictions in the Pearl River Basin. Full article

Amid the global drive to enhance public sector performance in the digital economy era, improving government spending efficiency has become a critical governance objective. This study investigates the impact of digital inclusive finance on government spending efficiency from a digital finance systems perspective using county-level panel data in China’s Yangtze River Delta for the period 2014–2022 and constructing the fixed-effects model and instrumental variable method to estimate the effect of digital inclusive finance and explore its underlying mechanisms. Heterogeneity across regions with varying economic development levels is analyzed, and fiscal pressure is examined as a potential mediating factor. The results indicate that (1) digital inclusive finance significantly enhances government spending efficiency, primarily through broad service coverage and deep usage of digital financial services such as mobile payments, digital credit, and insurance; (2) the positive effect is more pronounced in counties with lower government spending efficiency and economic development; and (3) fiscal pressure acts as a key transmission channel, with broader digital inclusive finance coverage helping to alleviate fiscal stress and improve government spending efficiency. These findings offer empirical insights into the role of digital finance in promoting effective and adaptive public financial governance. Full article

Achieving the synergistic effect of pollution reduction and carbon mitigation (PRCM) is a core pathway for promoting green and low-carbon transition and realizing the “dual carbon” goals, as well as a crucial mechanism for coordinating ecological environment governance with climate action. Based on panel data from three major urban agglomerations (Beijing–Tianjin–Hebei, Yangtze River Delta, and Pearl River Delta) between 2008 and 2019, this study employs network centrality and structural holes to characterize urban network positions (UNP), and systematically investigates the impact mechanisms and spatial heterogeneity of urban network positions on PRCM synergy using a dual fixed-effects model. The findings reveal that (1) urban network positions exert significant inhibitory effects on the overall synergy of PRCM, meaning higher centrality and structural hole advantages hinder synergistic progress. This conclusion remains valid after robustness checks and endogeneity tests using instrumental variables. (2) Heterogeneity analysis shows the inhibitory effects are particularly pronounced in Type I large cities and southern urban agglomerations, attributable to environmental governance path dependence caused by complex industrial structures in metropolises and compounded pressures from export-oriented economies undertaking industrial transfers in southern regions. Northern cities demonstrate stronger environmental resilience due to first-mover advantages in heavy industry transformation. (3) Mechanism testing reveals that cities occupying advantageous network positions tend to reduce environmental regulation stringency and research and development investment levels. Conversely, cities at the network periphery demonstrate late-mover advantages by embedding environmental regulations and building stable technological cooperation partnerships. This study provides a theoretical foundation for optimizing urban network spatial configurations and implementing differentiated environmental governance policies. It emphasizes the necessity of holistically integrating network effects with ecological effects during new-type urbanization, advocating for the establishment of a multi-scale coordinated environmental governance system. Full article

Small and micro wetlands exhibit enduring ecological dynamics that critically inform urban development planning and biodiversity conservation strategies. Focusing on Wuxi City (a representative area under high-intensity anthropogenic pressure in China’s Yangtze River Delta urban agglomeration), we employ the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. By integrating multi-temporal remote sensing imagery (1980–2020) with field surveys, we quantitatively assess spatiotemporal variations in habitat quality, with particular emphasis on their enhancement effects. The key findings were as follows. (1) The overall habitat quality in Wuxi City declined significantly during the period of 1980–2020 based on 30 m resolution land-use/land cover (LULC) data. The area of “good” habitat increased marginally by 1.02%, while “fair” and “excellent” habitats decreased by 19.4% and 1.64%, respectively. Conversely, the area of “poor” habitat rose markedly by 28.71%. (2) Small and micro wetlands were identified using Support Vector Machine (SVM) classification on Landsat imagery, showing a transformation from abundance to scarcity and then back to abundance. Before 2000, these areas grew rapidly, reaching a peak of 4.04 × 10⁴ hm² in 2000. Afterward, there was a sharp decline from 2000 to 2005, followed by stabilization. (3) A comparison of two land-use scenarios revealed that incorporating small and micro wetlands significantly expanded high-quality habitat areas and reduced low-quality areas. The most notable expansion occurred in 2000, with high-quality habitat areas increasing by 12.30%. This study demonstrates that directly using existing land-use data for habitat quality simulation overlooks the influence of small and micro wetlands. It is recommended that habitat quality simulations include extracted small and micro wetland data to ensure accurate assessments. Full article

The Yangtze River Delta (YRD) region, located inside the Yangtze River Basin, functions as a vital ecological and economic area in China, with its natural environment directly impacting human existence. This study seeks to elucidate the spatial and temporal evolution of rural resilience in the Yangtze River Delta region and its underlying mechanisms by establishing a comprehensive assessment framework for rural resilience, thereby offering a scientific foundation and policy guidance for the region’s sustainable development. The research first established the DPSIR (driving force–pressure–state–impact–response) assessment index system. Subsequently, the entropy weighting method and TOPSIS were utilized to assess and rank the rural resilience levels in the Yangtze River Delta region (Shanghai, Jiangsu, Zhejiang, and Anhui) from 2012 to 2022. Ultimately, partial least squares structural equation modeling (PLS-SEM) was employed to examine the intrinsic logical relationships among the five dimensions of the DPSIR framework and to extract conclusions. The study effectively met the goals of SDG 7 (clean water and sanitation), SDG 8 (decent work and economic growth), and SDG 11 (sustainable cities and communities). The research indicated that (1) the resilience level in the Yangtze River Delta region initially declined, then increased, and eventually attained a condition of stabilization. Changes in the “driving force”, influenced by the “response level” and environmental “pressure”, have affected the resilience level of rural areas. There is heterogeneity in the assessment values and ranges of change among provinces, with the “impact” component exhibiting the most substantial evaluation value. The findings yield policy recommendations for the implementation of diverse regional governance, the establishment of connectivity mechanisms, the customization of strategies to address the specific deficiencies of each province, and the systematic enhancement of rural resilience. Full article

In the past 5 years, the COVID-19 pandemic has experienced frequently changing variants contextualizing immune evasion. The emergence of Omicron with >30–50 mutations on the spike gene has shown a sharp divergence from its relative VOCs, such as WT, Alpha, Beta, Gamma, and Delta. The requisition of prime boosting was essential within 3–6 months to improve the Nab response that had been not lasted for longer. Omicron subvariant BA.1.1 was less transmissible, but with an extra nine mutations in next variant BA.2 made it more transmissible. This remarkable heterogeneity was reported in ORF1ab or TRS sites, ORF7a, and 10 regions in the genomic sequences of Omicron BA.2 and its evolving subvariants BA.4.6, BF.7, BQ.2, BF. 7, BA.2.75.2, and BA.5 (BQ.1 and BQ.1.1). The mutational stability of subvariants XBB, XBB 1, XBB 1.5, and XBB 1.6 conferred a similar affinity towards ACE-2. This phenomenon has been reported in breakthrough infections and after booster vaccinations producing hybrid immunity. The reduced pathogenic nature of Omicron has implicated its adaptation either through immunocompromised individuals or other animal hosts. The binding capacity of RBD and ACE-2, including the proteolytic priming via TMPRSS2, reveals its (in-vitro) transmissibility behavior. RBD mutations signify transmissibility, S1/S2 enhances virulence, while S2 infers the effective immunogenic response. Initial mutations D614G, E484A, N501Y, Q493K, K417N, S477N, Y505H, and G496S were found to increase the Ab escape. Some mutations such as, R346K, L452R, and F486Vwere seen delivering immune pressure. HR2 region (S2) displayed mutations R436S, K444T, F486S, and D1199N with altered spike positions. Later on, the booster dose or breakthrough infections contributed to elevating the immune profile. Several other mutations in BA.1.1-N460K, R346T, K444T, and BA.2.75.2-F486S have also conferred the neutralization resistance. The least studied T-cell response in SARS-CoV-2 affects HLA- TCR interactions, thus, it plays a role in limiting the virus clearance. Antigenic cartographic analysis has also shown Omicron’s drift from its predecessor variants. The rapidly evolving SARS-CoV-2 variants and subvariants have driven the population-based immunity escape in fully immunized individuals within short period. This could be an indication that Omicron is heading towards endemicity and may evolve in future with subvariants could lead to outbreaks, which requires regular surveillance. Full article

The Okavango River is a transboundary waterway that flows through Angola, Namibia, and Botswana, forming a significant alluvial fan in northwestern Botswana. This fan creates a Delta that plays a vital role in the country’s GDP through tourism. While research has primarily focused on the Delta, the river’s catchment area in the Angolan highlands—its main water source and critical for downstream flow—has been largely overlooked. The basin is under pressure from development, water abstraction, and population growth in the surrounding areas, which negatively affect the environment. These challenges are intensified by climate change, leading to increased water scarcity that necessitates improved management strategies. Currently, there is a lack of published research on the basin’s hydrology, leaving many hydrological parameters related to streamflow in the catchments inadequately understood. Most existing studies have employed single-site calibration methods, which fail to capture the diverse characteristics of the basin’s catchments. To address this, a SWAT model has been developed to simulate the hydrologic behaviour of the basin using sequential multisite calibration with data from five gauging stations, including the main river systems: Cubango and Cuito. The SUFI2 program was used for sensitivity analysis, calibration, and validation. The initial sensitivity analysis identified several key parameters: the Soil Evaporation Compensation Factor (ESCO), the SCS curve number under moisture condition II (CN2), Saturated Hydraulic Conductivity (SOL_K), and Moist Bulk Density (SOL_BD) as the most influential. The calibration and validation results were generally satisfactory, with a coefficient of determination ranging from 0.47 to 0.72. Analysis of the water balance and parameter sensitivities revealed the varied hydrologic responses of different sub-watersheds with distinct soil profiles. Average annual precipitation varies from 1116 mm upstream to 369 mm downstream, with an evapotranspiration-to-precipitation ratio ranging from 0.47 to 0.95 and a water yield ratio between 0.51 and 0.03, thereby revealing their spatial gradients, notably increasing evapotranspiration and decreasing water yield downstream. The SWAT model’s water balance components provided promising results, with soil moisture data aligned with the TerraClimate dataset, achieving a coefficient of determination of 0.63. Additionally, the model captured the influence of the El Niño–Southern Oscillation (ENSO) on local hydrology. However, limitations were noted in simulating peak and low flows due to sparse gauge coverage, data gaps (e.g., groundwater abstraction, point sources), and the use of coarse-resolution climate inputs. Full article

The Carboniferous–Permian strata in the Daning–Jixian Block, located on the eastern edge of the Ordos Basin, host multiple sets of tight gas reservoirs. However, systematic research on the characteristics and gas production differences of multilayer tight sandstone gas-bearing systems remains limited. Based on geochemical signatures, reservoir pressure coefficients, and sequence stratigraphy, the tight sandstone gas systems are subdivided into upper and lower systems, separated by regionally extensive Taiyuan Formation limestone. The upper system is further partitioned into four subsystems. Depositional variability from the Benxi Formation to the He 8 Member has generated diverse litho-mineralogical characteristics. The Shan 1 and He 8 Members, deposited in low-energy delta-front subaqueous distributary channels with gentle topography, exhibit lower quartz content (predominantly feldspar lithic sandstone and lithic quartz sand-stone) and elevated lithic fragments, matrix, and clay minerals (particularly chlorite). These factors increase displacement and median pressures, resulting in inferior reservoir quality. By comparing and evaluating the gas production effects under different extraction methods, targeted optimization recommendations are provided to offer both theoretical support and practical guidance for the efficient development of this block. Full article

This study assessed riverbank erosion and stability along the Mekong and Bassac Rivers to propose safe river corridors and mitigate erosion risks in the Mekong Delta. Using Landsat imagery (2000–2023), field surveys, and numerical simulations, we identified severe erosion hotspots, where erosion rates reach up to 40 m annually, in the meandering sections of the Mekong River,. In contrast, the Bassac River exhibited significant sedimentation, though this trend was diminishing due to upstream sediment deficits caused by hydropower dams. Stability assessments revealed optimal safety corridor distances ranging from 20 to 38 m, influenced by local geotechnical conditions and structural loads. A significant proportion of riverbanks in Dong Thap (88%) and An Giang (48%) do not comply with conservation standards, exacerbating erosion risks and threatening infrastructure. The results of this study highlight the urgent need for enforcing conservation regulations, implementing nature-based solutions like riparian buffers, and adopting sustainable land-use planning. By addressing the interplay between natural processes and anthropogenic pressures, these findings offer actionable insights to enhance riverbank stability, protect ecosystems, and sustain livelihoods in the Mekong Delta amidst growing environmental challenges. Full article

The rapid pace of urbanization is contributing to ecological degradation and poses a threat to regional ecological security. Addressing these issues requires effective strategies to mitigate existing environmental challenges. Ecological networks, as the spatial foundation for ecosystem services, play a critical role in reducing environmental degradation. By reconfiguring the spatial relationship between human activities and natural ecosystems, anthropogenic pressures on land can be alleviated. However, most current research focuses on administrative boundaries, which limits spatial continuity and regional coordination. Therefore, constructing ecological networks from a cross-regional perspective is essential for integrated ecological management. This study uses the Yangtze River Delta Ecological Green Integration Demonstration Area as a case study. We construct a blue–green ecological network by applying ecological footprint analysis, Morphological Spatial Pattern Analysis (MSPA), landscape connectivity assessments, the Minimum Cumulative Resistance (MCR) model, and gravity modeling. Practical strategies for integrating the ecological network into territorial spatial planning are also explored. The key findings are as follows: (1) The demonstration area contains 33 ecological source areas, including 20 primary sources located near administrative boundaries and central lakeshore wetlands. A total of 333 ecological corridors were identified. First-grade corridors are primarily located in rural areas, traversing agricultural land and water bodies. (2) We recommend corridor widths of 200 m for first-grade corridors, 60 m for second-grade corridors, and 30 m for third-grade corridors. These widths are based on species characteristics and land use types, and are found to be conducive to species migration and habitat connectivity. (3) We propose the development of tourism landscape zones from a cross-regional perspective, leveraging existing ecological and cultural resources. The multifunctionality of corridors is redefined through the integration of ecological and social values, enhancing their spatial implementation. This framework provides a practical reference for constructing cross-regional blue–green ecological networks and informs spatial planning efforts in other multi-jurisdictional areas. Full article

Compound dry–hot events refer to climate phenomena where drought and high temperatures occur simultaneously. Compared to single extreme events, compound dry–hot events may have greater adverse impacts. This study uses high-spatial-resolution observational data (i.e., temperature, precipitation, and climate water balance) to cluster and identify spring compound dry–hot events in the Pearl River Basin over the past nearly 50 years. It further investigates the associated large-scale atmospheric circulation conditions during compound dry–hot events. Using three clustering methods and twenty-six evaluation criteria, six events are identified. These events primarily exhibit negative anomalies in precipitation and climate water balance and positive anomalies in temperature. The spatial distribution results show that moisture deficits during compound events are mainly concentrated in the eastern Pearl River Basin, especially in the Pearl River Delta region. An atmospheric circulation analysis indicates that spring compound dry–hot events in the Pearl River Basin are commonly accompanied by persistent abnormal high-pressure systems, relatively weak westerly transport from subtropical regions such as the Indian Ocean and the Bay of Bengal (20–25 °N), and limited moisture input from the western Pacific region. The results of this study can help to better understand and analyze the risk changes of extreme events in the context of global warming. Full article

Ozone (O₃) is a crucial atmospheric component that significantly affects air quality and poses considerable health risks to humans. In the coastal areas of the Yangtze River Delta, typhoons, influenced by the subtropical high-pressure system, can lead to complex ozone pollution situations. This study aimed to explore the causes, sources, and health risks of O₃ pollution during such events. Ground-based data from Jiaxing City’s key ozone precursor (VOCs) composition observations, ERA5 reanalysis data, and models CMAQ-ISAM and PMF were employed. Focusing on the severe ozone pollution event in Jiaxing from 3 to 11 September 2022, the results showed that local ozone production was the main contributor (60.8–81.4%, with an average of 72.3%), while external regional transport was secondary. Concentrations of olefins and aromatic hydrocarbons increased remarkably, playing a vital role in ozone formation. Meteorological conditions, such as reduced cloud cover during typhoon periphery transit, promoted ozone accumulation. By considering the unique respiratory exposure habits of the Chinese population, refined health risk assessments were conducted. Acrolein was found to be the main cause of chronic non-carcinogenic risks (NCRs), with NCR values reaching 1.74 and 2.02 during and after pollution. In lifetime carcinogenic risk (LCR) assessment, the mid-pollution LCR was 1.73 times higher, mainly due to 1,2-dichloroethane and benzene. This study presents a methodology that is readily adaptable to analogous pollution incidents, thereby providing a pragmatic framework to guide actionable local government policy-making aimed at safeguarding public health and mitigating urban ozone pollution. Full article