Search Results (2,929)

Cold exposure may influence reproductive health through vascular changes, yet its mechanisms remain underexplored. This study aimed to investigate the impact of cold exposure on uterine blood vessels and the expression of the AMPK/PGC-1α gene and protein in adult female SD rats. A primary dysmenorrhea model was established in female Sprague Dawley rats and subjected to continuous cold exposure. Changes in body weight, ear temperature, and estrous cycle were observed. Superoxide dismutase (SOD) activity and adenosine triphosphate (ATP) levels were measured to assess oxidative stress. Uterine tissue morphology was assessed via small animal ultrasound, microcirculation observed using RFLSI imaging, and vascular morphology along with caspase-3 and AMPK expression evaluated histologically and immunohistochemically. CD31 and TUNEL double immunofluorescence were used to assess vascular endothelial apoptosis levels. Western blot was used to analyze Bax, BCL-2, and pAMPK/AMPK expression levels. In vitro injury models were used to treat human umbilical vein endothelial cells (HUVECs) with cold stimulus using the AMPK inhibitor Compound C. RT-PCR quantified Bax, AMPK, p53, and PGC-1α expression. Hypothermia-exposed rats exhibited significantly reduced body weight and ear temperature (p < 0.05), prolonged estrous cycle (p < 0.01), and decreased uterine index (p < 0.01), accompanied by reduced SOD and ATP levels (p < 0.01, p < 0.05). Ultrasound and flow imaging revealed decreased uterine blood flow velocity in the hypothermia group (p < 0.01). Histomorphology revealed disorganized uterine cell arrangement, reduced uterine vessel count (p < 0.01), and increased mean vessel area (p < 0.01) in cold-exposed uteri. Immunofluorescence detection revealed increased vascular endothelial cell apoptosis (p < 0.05). Western blot results showed that proapoptotic protein Bax was upregulated (p < 0.01), Bcl-2 was downregulated (p < 0.05), p-AMPK and p-AMPK/AMPK ratio were elevated (p < 0.01) after cold exposure; Rt-qPCR results indicated that Bax and P53 mRNA were increased (p < 0.01), while PGC-1α expression was elevated (p < 0.01). Rt-qPCR results showed elevated Bax and p53 mRNA (p < 0.01), along with increased AMPK and PGC-1α expression (p < 0.01) in the cold-exposed group. In human umbilical vein endothelial cells (HUVECs), compound C attenuated cold-induced effects (p < 0.01) and downregulated Bax and AMPK expression (p < 0.01). Cold exposure exacerbates uterine oxidative stress and energy imbalance, disrupts microcirculatory homeostasis, and induces endothelial cell apoptosis. Excessive phosphorylation of AMPK may co-activate PGC-1α, jointly contributing to cold-induced uterine dysfunction and exacerbated dysmenorrhea. This study reveals potential signaling pathways underlying cold-induced uterine vascular abnormalities, providing novel theoretical foundations and targeted intervention strategies for the prevention and treatment of primary dysmenorrhea. Full article

Understanding how climate extremes affect crop growth in humid–subtropical hilly regions is essential for climate-smart agriculture, yet phenology-resolved evidence remains limited. We combined 20 ETCCDI extreme climate indices (1960–2024) with field records of wheat and maize production (2005–2024) from the hilly area of southwest China, and quantified climate–crop linkages using Mantel tests and generalized additive models; persistence and prospective tendencies were evaluated using Hurst (H) and Mann–Kendall statistics. Warming extremes intensified, with significant increases in TXx (0.22 °C decade⁻¹), SU25 (2.48 days decade⁻¹), and DTR (0.47 °C decade⁻¹), while TNx and TNn declined and frost days increased; most precipitation intensity indices showed no significant trends except CDD, which increased by 1.73 days decade⁻¹. Seasonally, warm extremes and CDD strengthened during the maize season, whereas climatic conditions during the wheat season were comparatively more favorable. Climate impacts on crop growth were stage-dependent, typically lagging by 1–2 months: wheat biomass was positively associated with TXx/TNx (strongest near heading), whereas maize production was more sensitive to temperature extremes (negative) and precipitation frequency indices; CDD significantly affected both crops. These findings suggest that compound heat–drought risks for maize could increase under the persistence and trend signals observed in the historical record, while modest warming may benefit wheat but cold extremes could remain a constraint for management. Full article

Schizothorax wangchiachii, as a cold-water fish, is a predominant or common species in high-altitude areas with large population sizes. It is among the main edible economic fish species in the production area. We used genotype sequencing (GBS) technology to analyze the genetic diversity and population structure of 10 wild populations in the Jinsha River and Yalong River basins of the upper Yangtze River. A total of 724,858 single-nucleotide polymorphisms (SNPs) were detected in these 10 wild populations. The population genetic diversity was low; however, the degree of genetic differentiation was not significant. The populations from the Jinsha River and Yalong River could not be clustered separately on the basis of the SNPs. The Panzhihua (PZH) and Wudongde (WDD) populations from the Jinsha River exhibited gene flow with the Yajiang (YJ) population from the Yalong River, and a secondary pulse of gene flow subsequently connected the PZH and WDD populations to the upper-Jinsha population Suwalong (SWL). The demographic history of S. wangchiachii, reflected in its effective population size (N_e), has been influenced by the uplift of the Qinghai–Tibet Plateau (QTP). Furthermore, the identified SNPs are functionally associated with key cellular processes, environmental adaptation, and metabolism. These findings provide critical genomic insights that can inform conservation strategies and support the sustainable utilization of wild S. wangchiachii resources. Full article

Rural households in cold regions still rely heavily on coal for cooking and domestic hot water, while single renewable energy sources suffer from intermittency and limited system-level assessment. This study proposes a solar–biogas complementary energy supply system integrating evacuated-tube solar collectors, an above-ground anaerobic digester, thermal storage, and biogas utilization for rural residential applications in Minqin, Northwest China. A dynamic system-wide model was developed by coupling TRNSYS with nonlinear representations of anaerobic fermentation and biogas boilers, enabling hour-by-hour simulation of energy production, conversion, storage, and consumption. Field measurements were used for validation, and the root mean square deviation between simulated and measured temperatures and gas production remained below 10%. During the heating season, the solar subsystem supplied 10% of the digester heating demand and 90% of the domestic hot-water load, while the biogas subsystem contributed 9.29% and 90.71%, respectively. The system delivered 4728.96 MJ of heat against a seasonal demand of 4636.22 MJ, fully meeting user requirements. A comprehensive 3E (energy–environment–economic) assessment shows that, compared with traditional rural energy supply modes, the proposed system reduces CO₂ and NOx emissions by 65.85% and 98.13%, respectively, and demonstrates favorable economics with a benefit–cost ratio of 2.41 and a discounted payback period of 3.27 years. The proposed modeling and evaluation framework provides a replicable solution for clean energy substitution and circular waste utilization in rural areas. Full article

The reuse of milled pavement material, known as RAP (Reclaimed Asphalt Pavement), represents one of the major current challenges in highway engineering worldwide. There is no doubt that the most valuable application of this residue is its use in the production of new hot asphalt mixtures, incorporating the highest possible RAP content, a process that requires adaptations in residue processing at asphalt plants. In Brazil, the RAP content added to these mixtures is limited to a maximum of 25%. Consequently, alternative applications have gained prominence in the country to increase RAP utilization in pavement engineering, such as its use in cold premixed asphalt mixtures. This study aimed to evaluate the performance of cold asphalt mixtures containing different RAP contents through mechanistic-empirical analyses of a reference pavement structure, using the modelling framework adopted in the Brazilian Asphalt Pavement Design Method (MeDiNa). After Marshall mix design and volumetric and mechanical characterization of mixtures containing 0%, 10%, 20%, 30%, and 40% RAP, stiffness and fatigue parameters were used to estimate the evolution of cracked area in the reference pavement, with each mixture applied as the surface layer under different traffic levels. The results demonstrated that pavement performance improved for all RAP contents evaluated compared to the mixture without RAP, with the mixture containing 30% RAP showing the best overall performance. Full article

A considerable proportion of perishable goods, including fruits and vegetables, deteriorate prior to reaching customers. Inadequate refrigeration infrastructure, particularly in developing nations with arid climates and markets distant from agricultural sources, accounts for most of these losses. A food cold chain has three primary phases: pre-cooling, cold storage, and refrigerated transportation. All phases of the cold chain rely fundamentally on refrigeration to preserve perishable products at designated temperatures, relative humidity, and CO₂ concentrations, thus prolonging their shelf life. Solar-driven or aided refrigeration systems use solar energy to power cooling systems and preserve the food in the cold chain. These systems are especially beneficial in off-grid or developing areas for preserving perishable goods such as fruits, vegetables, and other food items, mitigating postharvest losses that can exceed 30–50% in areas with inconsistent energy supplies. Despite progress in efficiency and scalability, numerous research gaps remain across technological, economic, social, policy, and regional dimensions, including technical aspects, optimization, and integration. There is a need to enhance energy-efficient designs, particularly by managing solar intermittency to address non-uniform cooling, which leads to inconsistent ripening and spoilage, and by integrating sustainable refrigerants to mitigate environmental impact. Further development is necessary for micro-scale, transportable, or decentralized systems designed for small farms, while economic and financing obstacles include high upfront costs and limited financial accessibility. Substantial deficiencies exist in creating affordable models and funding channels for small-scale agriculturalists. Addressing these deficiencies could expedite adoption, thereby reducing global food loss and waste (accounting for 8–10% of GHG emissions) while improving food security. Future research must emphasize multidisciplinary methodologies that amalgamate engineering, economics, and social sciences to provide comprehensive solutions. Full article

Rapid urbanization has significantly increased energy demand in buildings, which now represent nearly 30% of global energy use. In India, buildings are built across highly varied climatic conditions, from hot-dry and warm-humid to cold, high-altitude areas, making climate-responsive envelope design essential to enhance thermal performance. Among envelope components, roofs are the most exposed to solar and outdoor thermal loads, playing a key role in managing indoor heat transfer. This study offers a parametric analysis of climate-responsive roof design strategies for India’s five main climatic zones, using transient simulations and statistical evaluation. The effectiveness of insulation placement, insulation material and thickness, and external surface absorptivity was systematically assessed based on roof heat gain and heat loss. Results indicate that over-slab insulation can lower roof heat gain by approximately 15–35% compared to under-slab insulation in warm-humid, hot-dry, composite, and temperate zones. In comparison, under-slab insulation decreases heat loss by about 10% in colder areas. Among insulation materials, 50 mm polyurethane foam (U = 0.433 W/m²·K) consistently outperformed extruded polystyrene and expanded polystyrene, achieving 82–83% reductions in maximum heat gain in cooling-dominated climates and 89% reductions in heat loss in cold regions relative to uninsulated roofs. When combined with a white reflective surface finish (α = 0.26), the total heat transfer reduction increased further to 89–92%. Surface treatments alone cut heat gain by 37–51% in non-cold climates, highlighting their potential as cost-effective retrofit options. Statistical analysis confirmed that dry-bulb temperature is the primary climatic factor influencing roof heat transfer (R² = 0.86–0.98, p < 0.0001), while solar radiation had a weaker effect, especially in optimized roof systems. The findings emphasize the importance of climate-specific roof design and demonstrate that insulation U-value has a greater impact on thermal performance than surface absorptivity, although both are significant. This research offers practical, climate-adjusted guidance for architects, engineers, and policymakers to enhance the thermal performance of roofs in Indian buildings. It supports the development of more resilient, energy-efficient building envelopes. Full article

Dinophysis acuminata, the main agent of diarrhetic shellfish poisoning (DSP) worldwide, shows a high variability in morphology and toxin content between strains from contrasting habitats. Most frequent uncertainties in morphological discrimination are within the “D. acuminata complex”, but confusion with other species (e.g., D. norvegica, D. fortii) also occurs. Here we describe a unique PTX2-containing population of Dinophysis cf acuminata observed during opportunistic samplings in San Rafael Lagoon (Chilean Patagonia), the only tidewater glacier lagoon remaining in the glacier with the world’s lowest latitude. Dinophysis acuminata was the only Dinophysis species observed during three seasonal surveys in the well-mixed cold (4–7° C) and brackish (salinity 14–15) waters of the lagoon. Cell densities ranged from 500 cells L⁻¹ (winter) to 2800 cells L⁻¹ (summer). Partial sequences of their ITS rDNA aligned them with D. acuminata strains from Europe and North America, and sequences of their stolen plastids 23S rDNA confirmed ciliates of the Mesodinium rubrum + major complex as their prey and plastid source. All these reasons make this lagoon a highly sensitive area and natural laboratory for climate change-related topics and Dinophysis issues related to (i) the effect of long-term exposure of marine fauna to pectenotoxins and (ii) the adaptations of D. cf acuminata to persist in a unique ecosystem with austral water characteristics located in a warm temperate latitude light regime. Results here add knowledge to the biogeography and habitat ranges of D. acuminata and the problems faced to monitor and provide early warning of its distribution. Full article

This study explores the hydrochemical and thermal characteristics of a fault-controlled geothermal field within the Northern Qinghai Lake Coalfield Area on the northeastern Qinghai–Tibetan Plateau (QTP). This research integrates hydrochemical analyses, isotopic tracers, and the regional geological framework to define hydrochemical signatures, identify recharge sources and flow paths, assess cold–hot water mixing, estimate reservoir temperatures, determine circulation depths and residence times, and explain the geothermal system’s formation. Systematic sampling included geothermal waters, cold springs, and surface waters, followed by laboratory analysis of major ions, stable isotopes (δ²H, δ¹⁸O), radiocarbon (¹⁴C), and tritium (³H). The geothermal water is categorized as a low-temperature, weakly acidic to near-neutral HCO₃-Ca•Mg type, exhibiting temperatures from 35.6 to 46.2 °C. Isotopic analyses indicate that cold spring and river waters align with the local meteoric water line, while geothermal waters display distinct isotopic signatures, suggesting deeper circulation. A silica–enthalpy mixing model reveals substantial cold-water mixing during upwelling, with mixing ratios between 74.5% and 85.6%. The corrected recharge elevation is estimated to be 4378–4456 amsl, implying a primary recharge zone in the branch of the Qilian mountains—the middle section of Datong Mountain to the northeast. Geothermometry, employing quartz and chalcedony temperature scales and accounting for mixing, estimates reservoir temperatures of 150–202 °C. The calculated circulation depth spans 3211–4291 amsl. Low tritium levels and carbon dating suggest a deep-cycling system predating 1952, characterized by deeply circulating “ancient water”. The geothermal system’s development is associated with regional tectonics, fault systems, and the Kesuer Formation (J_xk) acting as the reservoir. This study provides a scientific foundation for the development and sustainable use of geothermal resources in the northern Qinghai Lake region and offers insights applicable to comparable fault-controlled geothermal systems across the QTP. Full article

With the rapid development of the social economy, island ecosystem services (ESs) are facing increasingly severe disruptions from human activities. This study constructs an integrated analytical framework of spatiotemporal changes–driving mechanisms–trade-offs/synergies. It aims to support regional sustainability by assessing the spatiotemporal patterns of ESs in the Zhoushan Archipelago, identifying key ecological functional zones and areas with high trade-offs and synergies, in order to formulate management strategies for long-term ecological balance. The results indicate that all four ESs in the Zhoushan Archipelago exhibited declining trends from 2000 to 2020. Spatially, these four ESs collectively exhibit a distribution pattern characterized by higher values in the south and lower values in the north. The cold spot and hot spot analysis results indicate that both the significant cold spot areas and significant hot spot areas have expanded, with noticeable changes occurring on Zhoushan Island, Daishan Island, and Liuheng Island. Based on these spatiotemporal variation characteristics, ecological functional zoning was conducted. The results show that the area of ecologically vulnerable zones has significantly increased, while the area of other functional zones has decreased. Driving factor analysis reveals that the land use/land cover, annual average precipitation, digital elevation model, slope, and normalized difference vegetation index have the most significant impact on the spatial heterogeneity of ESs. Furthermore, trade-off/synergy analysis among ESs was conducted. Spatially, high-trade-off areas are primarily located in central Zhoushan Island, Liuheng Island, Jintang Island, Daishan Island, and Sijiao Island. High-synergy areas are mainly distributed in northern Zhoushan Island, Qushan Island, Taohua Island, and the Ma’an Archipelago. These findings provide a scientific basis for the ecological conservation and restoration of the Zhoushan Archipelago, offering significant reference value for promoting sustainable development in island regions. Full article

Urban expansion and spatial restructuring significantly influence the urban thermal environment. This study investigates the central urban area of Jinan, developing a multi-dimensional spatial structure index system that integrates terrain, 2D/3D morphology, and layout based on multi-source data. Land surface temperature (LST) was derived from remote sensing imagery. Using road networks and triangulated irregular networks (TINs) generated from a digital elevation model (DEM), hybrid analysis units were created. Pearson correlation and bivariate global/local spatial autocorrelation analyses were applied to examine the mechanisms and spatial heterogeneity of how urban spatial structure affects LST. The results showed that (1) LST was strongly associated with urban spatial structure. Among the 12 significantly correlated indicators, building density showed the strongest positive correlation with LST (r = 0.5883), while DEM mean had the strongest negative correlation (r = −0.7444), indicating that compact built-up areas intensified heating, whereas terrain most strongly moderated surface temperature. (2) LST and indicator correlations varied with elevation. LST showed a negative correlation with the standard deviation of DEM, suggesting that greater terrain variability enhances cooling effects. This spatial variation in the dominant drivers of the thermal environment reflects a clear divergence of influencing factors across different elevational zones. The thermal environment exhibits a pronounced north–south split: cooling effects prevail in the south due to terrain, while warming effects dominate in the north due to building forms. (3) Bivariate spatial autocorrelation revealed clear spatial heterogeneity. High–high clustering of LST and spatial structure indicators in the northern plain denoted heat-aggregated zones. Low–low clustering in the topographically complex, sparsely built south formed cold-source zones, and transitional areas showed mixed high–low and low–high clustering. (4) Based on these findings, a zonal governance framework was advocated, prioritizing terrain assessment followed by spatial structure optimization. This promoted a shift from uniform to precise, zone-based thermal environment management, laying a scientific foundation for sustainable spatial planning. Full article

In the Yingjiang area of western Yunnan, precipitation is high throughout the year, making it one of the regions with the highest annual precipitation in mainland China. Extreme rainfall in this region often triggers severe flooding, yet the key mechanism of water vapor transport underlying abnormally heavy precipitation remains unclear. This study used automatic weather station observations of precipitation, the fifth-generation atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts, and Global Data Assimilation System (GDAS) data to analyze, for the first time, large-scale water vapor transport, precipitation mechanisms, and the primary water vapor sources and their contributions in this region. The results show the following: In the Yingjiang area, the water vapor sources at all height levels in summer are dominated by the southwest monsoon water vapor transport pathways, such as the Bay of Bengal and the Arabian Sea, with their total contributions to specific humidity and water vapor flux exceeding 70%. This indicates that low-latitude sea areas such as the Bay of Bengal and the Arabian Sea serve as key moisture source regions for Yingjiang in the global water vapor cycle. Water vapor transport over the windward slope causes strong low-level convergence and high-level divergence phenomena, and the suction effect leads to strong upward motion near the 850 hPa level. The pseudo-equivalent potential temperature isolines tilt along the mountain slope, maintaining an unstable stratification characterized by warm, humid lower layers and cold, dry upper layers, providing favorable thermal conditions for precipitation. In addition, in the summer of 2020, abnormally high southwest seasonal wind and air transport, combined with strong low-level convergence and high-level divergence of the vertical circulation structure, were key factors causing the abnormally high precipitation. This study provides an important reference for the prediction of extreme precipitation and the early warning of rainstorm disasters in the southwest monsoon region in the context of global climate change. Full article

Pitaya (Hylocereus undatus) is a typical Crassulacean Acid Metabolism (CAM) plant with strong drought tolerance but high sensitivity to low temperatures. In this study, the responses of pitaya cultivated in the karst areas of Guizhou Province in southwest China to drought and low temperature were examined in winter seasons. The stems of ‘Zihonglong’ pitaya were used as materials to investigate the physiological responses to cold temperatures of pitaya stems under different water conditions, so as to understand the effects of drought stress on the response to low temperatures. The results showed that the severity of chilling injury in pitaya stems was influenced by cold degree and duration and temperature variation. Under sustained low-temperature conditions, the lower the temperature and the longer the duration, the more severe the chilling injury, particularly at 4 °C and below. Drastic temperature rise after exposure to low temperature of 5 °C aggravated the damage, especially when the temperature rise exceeded 10 °C. Compared to normally irrigated plants, those subjected to drought pretreatment exhibited milder chilling injury and higher survival rates under a temperature shift from 5 to 20 °C. The drought-treated pitaya stems had significantly lower membrane leakage and malondialdehyde (MDA) and reactive oxygen species (ROS) contents compared with the well-watered control under different temperature increases starting from 5 °C. Drought significantly reduced soluble sugars and soluble proteins but increased proline under a temperature shift from 5 to 20 °C. It significantly enhanced the activities of catalase (CAT) and ascorbate peroxidase (APX) under temperature shifts from 5 to 10 or 20 °C, but had no significant effect on peroxidase (POD) and superoxide dismutase (SOD). Drought also significantly increased ascorbic acid (ASA) content but significantly reduced glutathione (GSH). It is concluded that a drastic post-cold temperature rise causes more severe damage than the cold temperature itself. Drought pretreatment increases the chilling tolerance of pitaya stems. This effect involves an enhanced ASA-GSH cycle, which strengthens ROS scavenging and prevents membrane damage. Full article

Permafrost thickness serves as a critical indicator of hydrogeological conditions in cold regions and significantly influences the safety of engineering infrastructure. Due to the combined effects of climate, ecology, and human activities, the thermal characteristics and spatial distribution of permafrost in the Greater and Lesser Khingan Mountains of Northeast China exhibit high complexity, rendering existing permafrost thickness estimation methods largely inapplicable in this region. We developed an integrated estimation framework that bridges the gap between limited deep ground temperature measurements and regional-scale mapping. To overcome the scarcity of deep borehole (>20m) data, a physical-statistical inversion method was employed to derive permafrost base depths from shallow borehole temperature profiles, thereby expanding the foundational dataset to 104 representative sites. Integrating these ground observations with satellite-derived products (e.g., MODIS NDVI) and auxiliary environmental covariates (e.g., DEM-based topography and gridded climatic data), a Random Forest algorithm (RF) was applied to generate a 1 km-resolution permafrost thickness distribution map across Northeast China with a classification accuracy of 0.74. The results indicate that the average permafrost thickness in the study area is 47.71 ± 10 m, exhibiting a spatial pattern of thicker in the north and west, thinner in the south and east, and greater in mountainous areas than in plains. The top three influencing factors of permafrost thickness are atmospheric precipitation, surface thawing degree days (TDDs), and topographic position index (TPI), revealing that the thickness of discontinuous permafrost in northeastern China is primarily governed by local factors such as soil moisture, represented by the thick permafrost existed under a small patch of ground surface. This study provides a new methodological framework for estimating permafrost thickness in regions with limited ground temperature gradient measurement in deep boreholes. Full article

Snowmelt-season sediment hazards in cold regions are becoming increasingly complex under climate change, as rising air temperatures and rainfall-on-snow events enhance interactions between snow, meltwater, and sediment. Compound processes may generate hazard magnitudes that are inadequately captured when avalanches and debris flows are assessed independently. This study develops a first-order framework for assessing snowmelt-season sediment hazards, using the 2018 Nozuka Tunnel disaster in Hokkaido, Japan, as a case study. Numerical simulations for the three scenarios (avalanche flow, debris flow, and snow–sediment mixed flow) were conducted under identical topographic and numerical conditions to evaluate the influence of snow–sediment interactions on the flow behavior, affected area, and deposition characteristics. Key initiation and material parameters were constrained via inverse analysis (parameter-search calibration) using the observed deposition extent, and Sentinel-1 SAR-derived surface change areas were used as independent spatial information to assess the plausibility and spatial consistency of the simulated deposition footprint. Future hazard amplification was examined using projected climate conditions. The snow–sediment mixed-flow scenario produces larger affected areas and deposition volumes than simulations that treat avalanche- or debris flow processes independently, and its simulated deposition extent is spatially consistent with SAR imagery. Future hazards may be amplified under warmer and wetter conditions. The proposed framework integrates disaster records, topographic analysis, validated snow–sediment mixed-flow simulations, and impact-area estimations to support hazard assessment and disaster mitigation in snow-dominated cold regions. These insights support climate-adaptive, sustainable infrastructure risk management in snow-dominated cold regions. Full article