Search Results (5,294)

Land use change is closely related to land surface temperature (LST). Based on remote sensing data from 2001 to 2020, this study analyzed the spatiotemporal variations and driving mechanisms of daytime and nighttime LST in the Urumqi Metropolitan Area (UMA) by combining traditional methods with the eXtreme Gradient Boosting (XGBoost)–SHAP coupled model. Although the average LST trend in the region was one of warming, the pixel-level significance analysis indicated that statistically significant warming (p < 0.05) is concentrated mainly in the urban core (2.65% of the area), while the majority of the region (70%) showed a non-significant warming trend. LST displayed significant spatial clustering, with Moran’s I remaining above 0.990, indicating a positive spatial autocorrelation in spatial distribution. With the advancement of urbanization, the proportion of impervious surfaces increased from 0.87% to 1.14%, while wastelands consistently accounted for approximately 50% of the total area. Different land use types showed distinct effects on the urban heat island (UHI) phenomenon: water bodies, grasslands, and forests played cooling roles, whereas barren land and impervious areas were the main heat contributors. The XGBoost-SHAP analysis further revealed that the importance ranking of driving factors has evolved over time. Among these factors, Elevation dominates, while the influence of population-related factors increased significantly in 2020. This study provides a scientific basis for regulating the thermal environment of cities in arid regions from the perspective of land use. This study provides a scientific basis for regulating the thermal environment of arid-region cities from the perspective of land use. Full article

This research examines how perceived social support shapes the legal motivation of Chinese university students by unraveling the underlying psychological pathways. Integrating the relational legal socialization framework with self-determination theory, we test a moderated mediation model in which subjective social support, comprising emotional and informational resources from families, peers, and institutions, exerts both a direct effect on legal motivation and an indirect effect through core self-evaluation, which is characterized by stable, positive self-beliefs. Additionally, we investigate the role of objective social support, defined as concrete resources and formal assistance, in moderating the link between subjective support and core self-evaluation. Utilizing survey responses from 365 undergraduates across mainland China, mediation and moderated mediation analyses with bootstrapped confidence intervals demonstrate that subjective support significantly enhances legal motivation, partially via improvements in core self-evaluation. Crucially, the mediating influence of core self-evaluation is stronger when objective support is high, confirming the moderation hypothesis. These findings enrich legal socialization theory by bridging individual psychological processes with behavioral outcomes in a Chinese context and underscore the importance of simultaneously cultivating perceived support experiences and strengthening formal support structures to foster legal motivation and compliance among college students. Full article

The concrete protective layer in hydraulic tunnels is prone to abrasion by high-velocity sand-laden water, reducing structural durability. Accurate prediction of abrasion depth is key to rational hydraulic structure design. Existing studies have limitations: classical empirical models consider only a single factor, while early machine learning models fail to cover two core abrasion mechanisms (friction and impact) and lack meta-heuristic algorithm-based parameter optimization, leading to insufficient generalization and stability. This study aims to (1) establish a multi-source database with 690 cases (463 friction-dominated, 227 impact-dominated) covering multiple test standards (ASTM C944, ASTM C779, BIS: 1237-1980, ASTM C1138); (2) optimize hyperparameters of LightGBM, XGBoost, and CatBoost using Genghis Khan Shark Optimizer (GKSO) to build a hybrid ensemble model; (3) verify model performance and identify key factors via SHAP analysis. After preprocessing, input features were simplified to five: water–cement ratio, FA/CA (fine aggregate/coarse aggregate), age, T/V (test duration/velocity), and WRA content. Results show that GKSO-CatBoost performed best (test set R² = 0.982, RMSE = 0.1231 mm). SHAP analysis identified T/V and the water–cement ratio as key influencing features, providing clear directions for optimizing concrete mix proportions under different standard scenarios. This study provides a new method for hydraulic concrete abrasion prediction and a scientific basis for durability design oriented to specific test standards. Full article

In this study, we investigated the impact of incorporating energetic substituents such as –NO₂, –NH₂, –Cl, –F, N-methyl-N-nitro (CH₃–N–NO₂), and picryl on the detonation performance and stability of acridone-based compounds. The B3LYP/cc-pVTZ approach was applied to investigate the influence of substitutions on the stability and detonation properties of acridone derivatives. The results obtained exhibit the significant influence of both the type and position of substituents on the energetic performance and stability of the compounds studied. Notably, the acridone derivative bearing a picryl group and four –NH₂ substituents exhibited energetic properties superior to those of 2,4,6-trinitrotoluene (TNT). Its calculated velocity lies in the range [7.45–7.66] km/s, and its detonation pressure is [22.49–24.36] GPa; however, its stability is lower than that of core compounds. This reduction, however, is dependent on both the nature and number of substituents introduced. Full article

This study focuses on highway service areas. Building upon prior research that identified key influencing factors through surveys and ISM–MICMAC analysis, it constructs a tripartite evolutionary game model involving the government, service area operators, and carbon reduction technology providers based on stakeholder theory. Combined with MATLAB simulations, the model reveals the dynamic patterns of the carbon reduction system. The results indicate that government strategies exert the strongest influence on the system and catalyze the other two parties, followed by service area operators. Carbon reduction technology providers adopt a more cautious stance in decision-making. Government actions shape system evolution through a “cost-benefit-incentive” triple mechanism, with its strategies exhibiting significant spillover effects on other actors. Enterprise behavior is markedly influenced by Xinjiang’s regional characteristics, where the core barriers to corporate carbon reduction lie in the costs of proactive equipment and technological investments. The willingness of technology providers to cooperate primarily depends on two drivers: incremental baseline benefits and enhanced economies of scale. The core trade-off in government decision-making lies between the cost of strong regulation (Cg1) and the cost of environmental governance under weak regulation (Cg2). An increase in Cg1 prolongs the government’s convergence time by 233.3% and indirectly suppresses the willingness of enterprises and technology providers due to weakened subsidy capacity. Enterprises are relatively sensitive to the investment costs of carbon reduction equipment and technology, with convergence time extending by 120%. Technology providers are highly sensitive to incremental baseline returns (Rt), with stabilization time extending by 500%. Compared to existing research, this model quantitatively reveals the “cost-benefit-incentive” triple transmission mechanism for carbon reduction coordination in “grid-end” regions, identifying key parameters for strategic shifts among stakeholders. Based on this, corresponding policy recommendations are provided for all three parties, offering precise and actionable directions for the sustainable advancement of carbon reduction efforts in service areas. The research conclusions can provide a replicable collaborative framework for decarbonizing transportation infra-structure in grid-end regions with high clean energy endowments. Full article

The origin of life remains one of the most profound and enduring enigmas in the biological sciences. Despite substantial advances in prebiotic chemistry, fundamental uncertainties persist regarding the precise mechanisms that enabled the emergence of the first cellular entity and, subsequently, the foundational branches of the tree of life. After examining the core principles that define living systems, we propose that life emerged as a novel property of a prebiotically assembled system—formed through the integration of distinct molecular worlds, defined as sets of structurally and functionally related molecular entities that interact via catalytic, autocatalytic, and/or self-assembly processes. This emergence established a permanent system–process duality, wherein the system’s organization and its dynamic processes became inseparable. Upon acquiring the capacity to replicate and mutate its genetic program, this primordial organism initiated the evolutionary process, ultimately driving the diversification of life under the influence of evolutionary forces and leading to the formation of ecosystems. The challenge of uncovering the origin of life and the emergence of biodiversity is not solely scientific, it requires the integration of empirical evidence, theoretical insight, and critical reflection. This work does not claim certainty but proposes a perspective on how life and biodiversity may have arisen on Earth. Ultimately, time and scientific inquiry will determine the validity of this view. Full article

Hydrogen leakage is a critical safety concern for high-pressure storage systems, where orifice geometry significantly influences dispersion and risk. Previous studies on leakage and diffusion have mostly focused on closed or semi-closed environments, while thorough exploration has been conducted on open and unshielded environments. This work compares three typical orifice types—circular, slit, and Y-type—through controlled experiments. Results show that circular orifices generate directional jets with steep gradients but relatively low concentrations, with a 1 mm case reaching only 0.725% at the jet core. Slit orifices exhibit more uniform diffusion; at 1 mm, concentrations ranged from 2.125% to 2.625%. Y-type orifices presented the highest hazard, with 0.5 mm leaks producing 2.9% and 1 mm cases approaching the 4% lower flammability limit within 375 s. Equilibrium times increased with orifice size, from 400–800 s for circular and slit leaks to up to 900 s for Y-type leaks, some of which failed to stabilize. Response behavior also varied: Y-type leaks achieved rapid multi-point responses (as short as 10 s), while circular and slit leaks responded more slowly away from the jet core. Overall risk ranking was circular < slit < Y-type, underscoring the urgent need for geometry-specific monitoring strategies, sensor layouts, and emergency thresholds to ensure safe hydrogen storage. Full article

Against the global rollout of Carbon Border Adjustment Mechanisms (CBAMs), carbon tariffs have emerged as a core tool for developed economies to internalize environmental externalities—especially for energy-intensive imports that dominate cross-border carbon flows. However, emission information asymmetry, a critical barrier to implementing cross-border energy and environmental policies, undermines the design of optimal carbon tariffs, as it distorts the link between tariff levels and actual fossil energy-related emissions. This study develops a two-country analytical model to examine how biased assessments of exporters’ carbon intensity influence optimal tariff settings, exporters’ strategic behavior, and aggregate carbon emissions—with a focus on energy-intensive production contexts. The results show that underestimating carbon intensity reduces exporters’ compliance costs, incentivizing emission concealment; this weakens tariffs’ environmental stringency and may raise global emissions. Overestimation, by contrast, inflates exporters’ marginal costs, discouraging green investment and causing emission displacement rather than reduction. The analysis highlights a policy feedback loop wherein misjudged emission information distorts both trade competitiveness and environmental performance. This study concludes that a transparent, accurate, and internationally verifiable carbon accounting system is essential: it not only facilitates the effective implementation of CBAM but also aligns optimal carbon tariffs with CBAM’s dual goals of climate action and trade equity, while supporting global energy transition efforts. Full article

Urbanization in Cyprus has accelerated significantly over the past 35 years, driven by population growth, infrastructure development, and the expansion of urban centres. This rapid urban transformation has contributed to notable changes in the local climate, primarily through the intensification of the Urban Heat Island (UHI) effect—a phenomenon where urban areas experience significantly higher temperatures than surrounding rural regions. As global climate change continues to influence regional weather patterns, understanding and mitigating local climatic variations such as UHI becomes increasingly critical for sustainable development and public health. In Cyprus, the cities of Nicosia, Limassol, Larnaca, and Paphos have witnessed considerable land use changes, with a growing contrast between densely built urban cores and less developed surrounding areas. This contrast results in uneven energy absorption, reduced vegetation cover, and altered surface temperatures, further exacerbating the effects of climate change at the local level. Full article

The presence of fling step and forward directivity, as distinctive features of near-fault ground motions, can lead to substantial alterations in the seismic performance of reinforced concrete bridges. This study examines the seismic performance of reinforced concrete bridges with various deck slabs subjected to two distinct sets of earthquake events. One set is of forward-directivity records, and the other set is of fling-step records. Three-dimensional finite element models for the analyzed reinforced concrete bridges are constructed using the CSI-BRIDGE v26 software package, incorporating appropriate material and geometric nonlinearities. The developed bridge models are of three spans and have different deck slab systems, namely, box girder, RC girder, and hollow core slab bridges. Extensive nonlinear response time-history analyses of various configurations representing the examined RC bridges are performed to elucidate the impact of seismic loads, including forward-directivity and fling-step records, on the seismic response of supporting columns and deck slabs in the longitudinal direction. The numerical simulations indicate that ground vibrations with fling step significantly amplify the seismic response demands in both substructure and superstructure elements. Moreover, bridge type substantially influences the induced seismic responses, particularly supporting columns and deck slabs. Full article

As a critical raw material in the semiconductor and new energy sectors, antimony is a strategic mineral resource for nations to safeguard industrial chain security. However, the scarcity of its resources and the complexity of its trade pattern underscore the urgency of antimony-related research. This study aims to reveal the structural characteristics of the global antimony trade network and explore the external factors influencing trade. Based on global antimony trade data from 2007 to 2022, the characteristics of the antimony trade network were analyzed using the complex network analysis method, and the influencing factors of antimony trade were examined via the fixed effects model. The results show that the global antimony trade network maintains a density of 0.05–0.06, with an average path length of 2.4–2.7 and a network diameter that mainly fluctuates between 5 and 6. The average clustering coefficient fluctuates within the range of 0.35–0.45. Overall, the network exhibits the characteristics of stable transmission efficiency, loose overall connectivity, and local agglomeration without a consistent upward or downward trend. Countries such as Germany, China, and the United States occupy core positions in the network. The fixed effects model indicates that GDP and LOGISTICS development are key factors promoting trade, while TARIFFS and REGULATORY policies have a significant inhibitory effect on trade. Therefore, ① Focus on the High-End Development of the Antimony Industry Chain and Promote the In-Depth Integration of Antimony Trade with the Semiconductor and New Energy Industries; ② Improve the Cross-Border Logistics and Warehousing System for Antimony Trade to Ensure the Efficient Circulation of Strategic Resources; ③ Promote; Promote Tariff Liberalization in Antimony Trade and Eliminate Market Access Barriers; ④ Strengthen the Government’s Strategic Support for the Antimony Industry to Enhance Global Discourse Power in Antimony Trade; Trade; ⑤ Maintain Macroeconomic Stability and Flexibly Manage Exchange Rates to Safeguard the Resilience of Antimony Trade. Full article

To accurately analyze the dynamic response and driving mechanism of forest carbon sequestration in the core area of the Loess Plateau’s Returning Farmland to Forestry Project, this study takes the Beiluo River Basin as the research area. Using spatial autocorrelation, gravity model, a geodetector, and spatiotemporal geographically weighted regression models, it analyzes the spatiotemporal evolution of forest carbon sequestration and the spatial heterogeneity of its influencing factors based on 2000–2023 data. The results show the following: (1) Forest carbon sequestration in the basin increased by 13.55% from 2000 to 2023; its spatial pattern shifted from “middle reaches concentration” to “stable middle reaches core plus significant upper reaches growth”, with the gravity center moving “southeast then northwest”. (2) Forest carbon sequestration had significant positive spatial correlation, with hotspots in soil–rock mountain forest areas and cold spots in ecologically fragile or high-human-activity areas. (3) Natural ecological factors dominated forest carbon sequestration evolution, socioeconomic factors enhanced synergy, and evapotranspiration and NDVI had significant impacts. (4) Factor impacts had spatiotemporal heterogeneity, such as the decaying positive effect of precipitation and the “positive-negative-equilibrium” change in forestry value-added. This study provides scientific guidance for basin and Loess Plateau ecological restoration and “double carbon” goal achievement. Full article

Ore leaching constitutes a core step for achieving efficient utilization of mineral resources, primarily encompassing acid leaching and alkaline leaching methods. Currently, acid leaching technology has reached a high level of maturity and is widely applied in industry due to its advantages of fast reaction kinetics and broad applicability to various mineral types. However, the theoretical framework underpinning alkaline leaching systems remains relatively weak. Given the distinct advantages of alkaline leaching in processing ores containing alkaline gangue minerals, this review systematically examines chemical and microbial leaching techniques for metal ores under alkaline conditions. It focuses on elucidating the mechanisms and key influencing factors associated with different alkaline matrices, oxidants, external pressures, and microbial strains. Future development prospects are also discussed. The aim is to provide a theoretical foundation and practical guidance for advancing metal ore leaching technologies towards greener and more efficient directions. Full article

A general relativistic model of an astrophysical hypermassive extremely magnetized ultra-compact self-bound quark–gluon plasma (QGP: ALICE/LHC) object that is supported against its ultimate gravitational implosion by the simultaneous action of the vacuum polarization driven by nonlinear electrodynamics (NLED: ATLAS/LHC: light-by-light scattering)—the vacuum “awakening”—and the asymptotic freedom, a key feature of quantum chromodynamics (QCD), is presented. These QCD stars can be the final figures of the equilibrium of collapsing stellar cores permeated by magnetic fields with strengths well beyond the Schwinger threshold due to being self-bound, and for which post-supernova fallback material pushes the nascent remnant beyond its stability, forcing it to collapse into a hybrid hypermassive neutron star (HHMNS). Hypercritical accretion can drive its innermost core to spontaneously break away color confinement, powering a first-order hadron-to-quark phase transition to a sea of ever-freer quarks and gluons. This core is hydro-stabilized by the steady, endlessly compression-admitting asymptotic freedom state, possibly via gluon-mediated enduring exchange of color charge among bound states, e.g., the odderon: a glueball state of three gluons, or either quark-pairing (color superconductivity) or tetraquark/pentaquark states (LHCb Coll.). This fast—at the QGP speed of sound—but incremental quark–gluon deconfinement unbinds the HHMNS’s baryons so catastrophically that transforms it, turning it inside-out, into a neat self-bound QGP star. A solution to the nonlinear Tolman–Oppenheimer–Volkoff (TOV) equation is obtained—that clarifies the nonlinear effects of both NLED and QCD on the compact object’s structure—which clearly indicates the occurrence of hypermassive QGP/QCD stars with a wide mass spectrum ($0\lesssim {\mathrm{M}}_{\mathrm{Star}}^{\mathrm{QGP}}\lesssim$ 7 M_⊙ and beyond), for star radii ($0\lesssim R_{\mathrm{Star}}^{\mathrm{QGP}}\lesssim 24$ km and beyond) with B-fields (${10}^{14}\le {\mathrm{B}}_{\mathrm{Star}}^{\mathrm{QGP}}\le {10}^{16}$ G and beyond). This unexpected feature is described by a novel mass vs. radius relation derived within this scenario. Hence, endowed with these physical and astrophysical characteristics, such QCD stars can definitively emulate what the true (theoretical) black holes are supposed to gravitationally do in most astrophysical settings. This color quark star could be found through a search for its eternal “yo-yo” state gravitational-wave emission, or via lensing phenomena like a gravitational rainbow (quantum mechanics and gravity interaction), as in this scenario, it is expected that the light deflection angle—directly influenced by the larger effective mass/radius (${\mathrm{M}}_{\mathrm{Star}}^{\mathrm{QGP}}\left(B\right)$, ${\mathrm{R}}_{\mathrm{Star}}^{\mathrm{QGP}}\left(B\right)$) and magnetic field of the deflecting object—increases as the incidence angle decreases, in view of the lower values of the impact parameter. The gigantic—but not infinite—surface gravitational redshift, due to NLED photon acceleration, makes the object appear dark. Full article

The influence of CO₂ on the mechanical properties of shale is one of the key factors to consider for enhancing shale oil and gas exploitation and realizing CO₂ geological storage. In this paper, triaxial mechanical experiments of rock under real-time contact with CO₂ under different conditions were carried out for the Chang 7 shale of the Yanchang Formation in the Ordos Basin. The results show that under the influence of real-time contact with CO₂, the triaxial compressive strength of shale decreases with an average decrease of 3.77% and a maximum decrease of 6.58% under the experimental conditions. The elastic modulus increased with an average increase of 8.54% and a maximum increase of 11.95%. The core compression failure presents a small degree of multi-fracture complex failure. With an increase in CO₂ exposure time, temperature, and pressure, the triaxial compressive strength gradually decreases, the elastic modulus gradually increases, and the compression failure of shale core is gradually complicated. The variation in mechanical parameters with time, temperature, and pressure under the influence of CO₂ real-time contact was quantitatively described. The effect of gaseous CO₂ on shale mechanical parameters and core compression failure is significantly weaker than that of supercritical CO₂. This research provides theoretical and data support for supercritical CO₂-enhanced shale oil and gas recovery and carbon geological storage from a rock mechanics perspective. Full article