Search Results (2,942)

Quantifying dynamic urban resilience is critical for climate adaptation. This study assesses the spatiotemporal resilience of 6838 flood-affected communities across 39 Chinese cities using high-resolution human activity data. By establishing a multi-phase framework, we extract six metrics characterizing resistance and recovery trajectories. Results reveal a distinct resilience paradox: coastal cities, despite suffering deeper instantaneous shocks from typhoons, exhibit superior adaptive capacity compared to inland cities, which face chronic recovery deficits under rainstorm stress. Unsupervised clustering identifies 12 distinct resilience phenotypes, ranging from brittle collapse to adaptive growth. Structural analysis confirms a Matthew Effect where functional diversity and economic vitality enable resource-rich communities to bounce forward, while peripheral areas remain trapped in vulnerability. These findings underscore the need for resilience-based regeneration policies that prioritize spatial justice and resource optimization over static engineering standards. Full article

Cave microbiota comprise metabolically diverse organisms, including microalgae, among which Bacillariophyta (diatoms) represent one of the most prominent groups, inhabiting a wide range of substrates within cave ecosystems. In contrast to aerophytic cave habitats, aquatic cave environments remain poorly studied. Therefore, the main aims of this study were to determine the diversity, spatial distribution, and seasonal dynamics of diatom assemblages in the Ponorac Stream flowing through Ravništarka Cave, and to assess the influence of environmental variables on diatom diversity and distribution. Samples were collected from six sites along the Ponorac stream in May and November 2023. Physical and chemical water parameters showed only minor variation among sampling sites. In total, 148 diatom taxa belonging to 54 genera were recorded, including several rare diatom taxa. Diatom assemblages in the Ponorac stream were characterized by high taxonomic richness, high α-diversity, and pronounced community heterogeneity. Many taxa occurred in both seasons and across multiple sites, whereas several were restricted to a single season or exhibited clear site specificity. Most diatom index values indicated generally high ecological status. This study highlights the importance of aquatic cave habitats as reservoirs of diatom diversity and their value in studying temporal and spatial variation of their communities. Full article

Retronasal aroma strongly influences the flavor quality of low-alcohol Jiangxiangxing Baijiu. This study investigated the retronasal aroma differences between high- and low-alcohol samples (Sample-High and Sample-Low). Dynamic sensory evaluation revealed roasted, grain, floral and fruity, hay, and caramel notes were more pronounced in Sample-High, whereas Sample-Low exhibited stronger fatty and smoky notes, indicating insufficient retronasal aroma richness in Sample-Low. Analysis of 67 compounds showed no significant concentration differences, yet their retronasal olfactory thresholds varied markedly between alcoholic systems (ratio 1.04–4.75), leading to higher dose-over-threshold (DoT) values for several compounds in Sample-Low. Further analysis of the DoT distribution intervals showed Sample-High presented a more balanced distribution, whereas Sample-Low was strongly driven by several high-contribution compounds, which reduced the relative contributions of others. This unbalanced distribution may underlie the lower retronasal aroma richness observed in Sample-Low. These findings provide a new perspective for understanding retronasal aroma in low-alcohol Jiangxiangxing Baijiu. Full article

The river ecosystems of the Qinghai–Tibet Plateau, recognized as a vital component of the “Asian Water Tower,” possess unique hydrological conditions and extreme environments that have shaped key indicator groups, most notably zooplankton. The community dynamics and structural characteristics of these zooplankton exhibit regular spatio-temporal distribution patterns across elevational gradients and seasonal successions. However, the intrinsic mechanisms underlying community succession and their correlations with environmental factors remain poorly understood, and the primary environmental drivers influencing community structure require further elucidation. Based on systematic zooplankton surveys and environmental data collection conducted across the Lhasa River basin from 2019 to 2021, this study established a comprehensive species inventory comprising 113 taxa across four major groups, alongside a multi-dimensional environmental dataset. We analyzed the spatio-temporal heterogeneities of zooplankton community structures—including abundance, biomass, and diversity indices—across different seasons and river reaches. The results revealed the composition and seasonal turnover of dominant taxa, with rotifers accounting for 39.82% of the total taxonomic richness. Mean zooplankton abundance and biomass across the basin were 1.18 ind./L and 343.60 × 10⁻⁵ mg/L, respectively, with peak values observed during autumn and within the Chabalang Wetland. The zooplankton community structure in the upstream, midstream, and downstream reaches, as well as associated wetlands, was significantly correlated with specific environmental factors (p < 0.05), including ammoniacal nitrogen (NH₄⁺-N), magnesium (Mg²⁺), total hardness (TH), potassium (K⁺), iron (Fe²⁺), sodium (Na⁺), sulfite (SO₃²⁻), nitrate ion (NO₃⁻), chloride ion (Cl⁻), total phosphorus (TP), and sulfide (S²⁻). Cl⁻, TH, Mg²⁺, SO₃²⁻, and elevation (Ele) were the key environmental drivers significantly influencing zooplankton abundance across seasons (p < 0.05). Furthermore, zooplankton abundance decreased significantly with increasing elevation during the winter. This research deepens our understanding of community assembly mechanisms in plateau river ecosystems and provides a scientific foundation for aquatic biodiversity conservation and ecological management in the Lhasa River basin. Full article

The tractor road, as the core scene for autonomous driving of grain transport vehicles, is unstructured, complex, and obstacle-rich, leading to poor real-time performance and accuracy of joint road and obstacle detection with existing YOLOv5s. Furthermore, the reliability of passable area evaluation is low solely based on environmental factors. Therefore, YOLOv5s-C2S is proposed, fusing multi-scale features, attention mechanism, and dynamic features for joint detection. Firstly, YOLOv5s-CC is proposed for road detection by fusing context and spatial details and introducing Criss-Cross attention. Secondly, YOLOv5s-SGA is proposed for obstacle detection by grouped and spatial convolution, parameter-free attention, and adaptive feature fusion. By reusing YOLOv5s-CC weights, YOLOv5s-C2S shares low-level features and decouples high-level specificity. Based on the tractor road and obstacle information, combined with vehicle factors, a weighted scoring–based comprehensive method for passable area evaluation is proposed. Finally, the method was verified through experiments with an intelligent tracked grain transport vehicle using self-constructed datasets, including VOC_Road (11,927 images) and VOC_Obstacle (21,779 images). Compared with existing YOLOv5s, Deeplabv3+, FCN, Unet and SegNet, the mAP₅₀ of road detection by YOLOv5s-CC increased by over 1.2%. Compared with existing YOLOv5s, R-CNN, YOLOv7, SSD and YOLOv8n, the mAP₅₀ of obstacle detection by YOLOv5s-SGA increased by over 2%. Compared with YOLOv5s-SD, the mAP₅₀ of joint detection by YOLOv5s-C2S increased by 9.3%, and the frame rate increased by 7.0 FPS. The proposed passable area evaluation method exhibits strong robustness and reliability in complex environments, meeting the accuracy and real-time requirements in autonomous driving of grain transport vehicles. Full article

By adding Ce to high-strength low-alloy steel, the effects of heating parameters and Ce on grain growth were examined through in situ observation and dynamic analysis of grain growth behavior during heating, combined with precipitated phase analysis and pinning force calculations. In situ observation of the heating process revealed the behavior of grain growth and grain boundary migration in real time, providing an intuitive and accurate illustration of the effect of Ce on grain growth behavior. The mechanism of Ce’s role in refining austenite grains was clarified. The results revealed that at 1050 °C, Ce had little effect on grain growth. Ce delayed the grain coarsening temperature from 1050–1150 °C to 1150–1250 °C, resulting in grain refinement. The predicted results from the established dynamic model were consistent with the grain growth process, demonstrating high predictive accuracy. After Ce treatment, the activation energy for grain growth increased from 172.058 to 193.703 kJ/mol, representing a 12.58% rise, rendering grain growth more difficult. Within the holding temperature range, small spherical Nb-rich (Nb, Ti)(C, N) and large rectangular Ti-rich (Nb, Ti)(C, N) existed. The addition of 0.0070% Ce delayed the dissolution of Nb-rich carbonitrides. Finer precipitated phases and high-melting-point, fine Ce₂O₂S and CeAlO₃ inclusions at grain boundaries provided greater pinning force, inhibiting grain growth. Full article

Resource-based cities face unique land use challenges due to resource dependence and path lock-in, yet the driving mechanisms and future trajectories of their land use transitions remain underexplored. This study examines the Huaihai Economic Zone (HEZ), a representative coal-rich region in eastern China, to analyze land use changes from 2000 to 2023 and simulate 2036 scenarios under different development pathways. Using land use transfer matrices, dynamic degree metrics, and the Patch-generating Land Use Simulation (PLUS) model, we systematically identified spatiotemporal evolution patterns, quantified the contributions of driving factors, and projected multi-scenario future land use patterns. Results reveal that land use change in the study area was dominated by the conversion of cultivated land to construction land, alongside spatial restructuring from a monocentric to a polycentric network pattern. Notably, construction land expansion was least evident in the central Mining-Affected Zone, where land use changes remained relatively sluggish compared to other sub-regions. Driving factor analysis indicates that socio-economic factors primarily influenced changes in construction and cultivated land, while natural factors strongly affected ecological land and unused land. Multi-scenario simulations for 2036 demonstrate diverging trajectories: an urban development scenario would accelerate cultivated land loss and unused land expansion; a natural development scenario would maintain current pressures; and an ecological protection scenario would effectively curb urban sprawl while actively promoting ecological land recovery. This study concludes that transcending simple land use control to actively orchestrate “mining-urban-rural-ecological” spatial synergy is critical for achieving a sustainable transition in resource-based regions facing similar transformation pressures. Full article

4D millimeter-wave radar provides high-precision ranging capability and exhibits strong robustness under adverse weather and low-visibility conditions, but its point clouds are relatively sparse and suffer from severe elevation-angle measurement noise. Monocular cameras, by contrast, provide rich semantic information and high recall, yet are fundamentally limited by scale ambiguity. To exploit the complementary characteristics of these two sensors, this paper proposes a radar-camera fusion 3D multi-object tracking framework that does not rely on complex 3D annotated data. First, on the radar signal-processing side, a Gaussian distribution-based adaptive angle compression method and IMU-based velocity compensation are introduced to effectively suppress measurement noise, and an improved DBSCAN clustering scheme with recursive cluster splitting and historical static-box guidance is employed to generate high-quality radar detections. Second, a disparity-domain metric depth recovery method is proposed. This method uses filtered radar points as sparse metric anchors, performs robust fitting with RANSAC, and applies Kalman filtering for temporal smoothing, thereby converting the relative depth output of the visual foundation model Depth Anything V2 into metric depth. Finally, a hierarchical fusion strategy is designed at both the detection and tracking levels to achieve stable cross-modal state association. Experimental results on a self-collected dataset show that the proposed method achieves an overall MOTA of 77.93%, outperforming single-modality baselines and other comparison methods by 11 to 31 percentage points. This study provides an effective solution for low-cost and robust environment perception in complex dynamic scenarios. Full article

Glass fiber-reinforced epoxy composites were modified with carbon nanotubes (CNTs), Al₂O₃, and TiO₂ nanoparticles to comparatively evaluate their influence on tensile, flexural, and low-velocity impact performance within an integrated experimental–numerical framework. Nanoparticles were incorporated at controlled weight fractions to identify dispersion-controlled reinforcement regimes and the onset of heterogeneity-driven mechanical transitions. Among all formulations, 0.5 wt% CNTs provided the most pronounced static mechanical enhancement, increasing tensile strength to 419.50 MPa (≈21% improvement over the reference GF laminate) and flexural strength to 230.23 MPa (≈26% increase). In contrast, impact performance exhibited a non-monotonic evolution; the highest absorbed energy (9.64 J) was observed at 2 wt% CNTs, indicating that dynamic energy dissipation mechanisms do not necessarily scale proportionally with static strength gains. Oxide-filled systems demonstrated stiffness-dominated behavior, where increasing filler content amplified elastic mismatch and progressively reduced strength despite modulus enhancement. Finite element simulations conducted in ANSYS LS-DYNA (MAT_022) reproduced global stiffness trends within the dispersion-controlled regime. Tensile strength predictions agreed within 0–9% at optimal CNT loading, whereas larger deviations (up to ~33%) emerged under bending-dominated loading in oxide-rich systems, reflecting amplified sensitivity to microstructural heterogeneity. The coupled evolution of stiffness–strength decoupling (SSDI) and FEM deviation (η) enabled identification of a Composite Heterogeneity Threshold (CHT), defined as the nanoparticle concentration beyond which stiffness enhancement no longer translates into proportional strength or toughness improvement. Beyond this threshold, dispersion-induced heterogeneity not only reduces mechanical efficiency but also marks the boundary of homogenized continuum model adequacy across static and dynamic loading conditions. Full article

Archaeological evidence for prehistoric placer tin mining is rare due to the ephemeral nature of the workings and the associated tools in the dynamic setting of active river systems. Here, we report an additional line of evidence for metallurgical activities at stream tin mining in Serbia at Mt. Cer and Bukulja. Rivers at these locations contain Pb-rich-glass grains, many of which are also enriched in Cu and Sn. Compositionally, the detrital grains of glass are similar to the vitreous infillings on a bleached ceramic sherd found at Spasovine, an archaeological site situated on the bank of the tin-rich Milinska River. The high-Pb-bearing (average 42 wt%) and Sn-bearing (average 0.7 wt%) composition of the glass, along with the inclusions of secondary cassiterite, indicate that the slag was derived from the refinement of leaded bronze (i.e., lead removal). Although the detrital glass slag grains lack direct archaeological context, broader archaeological observations limit their production to either the Roman or Medieval Periods. The presence of Pb-Cu-Sn metallurgical glass grains in a river at Bukulja provides the first concrete evidence of prehistoric tin mining at this locality, which demonstrates that sluicing for crushed glassy residues is a viable means to prospect for as yet undiscovered sites of ancient metallurgical activities. Full article

Colored potato cultivars are rich in phenolic compounds that confer high antioxidant capacity; however, these beneficial metabolites could be susceptible to oxidation by polyphenol oxidases (PPOs), leading to enzymatic browning and the loss of antioxidant potential. Despite the agronomic relevance of this trade-off, the dynamics of the PPO gene family (StPPOs) gene expression in pigmented potatoes remains poorly characterized. Here, we present an integrated biochemical and molecular analysis of two purple-fleshed Peruvian landraces (Siriñacha and Angashungo), a partially pigmented landrace (Sapa), and non-pigmented cultivars, including the commercial cultivar Desirée. We quantified the total phenolic content, antioxidant capacity, and enzymatic browning index (EBI) using colorimetric and spectrophotometric methods. We also generated gene expression profiles of ten StPPO genes using semi-quantitative and digital PCR. Purple-fleshed cultivars exhibited significantly higher phenolic content and antioxidant capacity but also displayed accelerated browning kinetics compared to non- or partially pigmented genotypes. Expression analysis revealed cultivar-specific StPPO patterns, with StPPO2 and StPPO8 being markedly upregulated in pigmented materials, particularly StPPO8. These findings provide the first integrated biochemical and transcriptional evidence linking specific StPPO isoforms to enzymatic browning in colored potatoes, and highlight their potential for biotechnological applications. Full article

Latitudinal gradients are widely recognized as a key macro-environmental driver shaping microbial biogeographic patterns; however, the spatial organization of sediment archaeal communities in estuarine ecosystems and the mechanisms underlying their assembly remain insufficiently understood. This study is based on sediment samples collected from three representative estuarine regions spanning distinct latitudes along the Chinese coastline—the North China Sea (NCS), East China Sea (ECS), and South China Sea (SCS). Based on 16S rRNA high-throughput sequencing, combined with null-model inference and molecular ecological network (MEN) analyses, we characterized latitudinal patterns in archaeal community distributions, assembly processes, and cross-regional interaction architectures. The results showed that archaeal communities exhibited obvious spatial segregation across three regions, with both community richness and network complexity increasing significantly toward lower latitudes. Nitrate (NO₃⁻), ferric iron (Fe³⁺), and dissolved oxygen (DO) were identified as key environmental factors governing archaeal community structure. Notably, archaeal community assembly processes exhibited a clear latitudinal gradient: deterministic processes, particularly environmental filtering, were more obvious at lower latitudes, whereas the contributions of stochastic processes—including dispersal limitation and ecological drift—increased markedly at higher latitudes. A MEN analysis further revealed that archaeal networks at lower latitudes exhibited higher connectivity, modularity, and stability, suggesting that interspecific interactions may enhance ecosystem resistance to environmental disturbance under more stable environmental conditions. Overall, this study demonstrates that macro-environmental gradients jointly shape archaeal biogeographic patterns via multiple pathways, including modulation of environmental filtering, dispersal dynamics, and cross-regional interactions. These findings deepened our understanding of the stable mechanisms governing the diversity and biogeographical distribution of archaea in estuarine systems. Full article

Urban wetlands are acoustic hotspots where vegetation structure, hydrological dynamics, and anthropogenic noise interact, yet multi-season assessments of how vegetation influences avian soundscapes are limited. This study explored bird soundscape dynamics across forest, open forest grassland, and meadow habitats in Nanjing Xinjizhou National Wetland Park, eastern China, using passive acoustic monitoring during spring and autumn 2023. Twelve sampling points (four per vegetation type) were established, and six acoustic indices were calculated, including the Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Acoustic Evenness Index (AEI), Bioacoustic Index (BIO), Normalized Difference Soundscape Index (NDSI), and Acoustic Entropy Index (H). were calculated from 48-h recordings each season. Random forest models and redundancy analysis assessed the relationships between acoustic indices, fine-scale vegetation parameters (e.g., crown width, tree height, species richness), and anthropogenic factors (e.g., distance to roads/trails, surface hardness). Vegetation structure, particularly crown width, was the primary driver of avian acoustic diversity, with broad-crowned forests consistently exhibiting the highest acoustic complexity. In spring, anthropogenic factors such as trail and road proximity dominated soundscape variation, suppressing biological sounds. In autumn, with reduced human presence, vegetation structure emerged as the dominant factor, while bioacoustic activity remained elevated despite reduced peaks in acoustic complexity. Proximity to roads increased low-frequency (1–2 kHz) noise and suppressed mid-frequency (4–8 kHz) bird vocalizations, but trees with crown widths ≥4 m maintained higher acoustic diversity even near disturbance sources. This study demonstrates that vegetation structure mediates both resource availability and sound propagation, buffering the effects of anthropogenic disturbance in frequency-specific ways. Multi-season sampling is crucial for understanding the dynamic interplay between vegetation phenology and human activity that shapes urban wetland soundscapes. Full article

The self-directed channel (SDC) class of memristors employs a multilayer architecture that is designed to enable robust Ag ion conduction, long cycling lifetime, and thermal stability. While several layers contribute to mechanical and chemical reliability, two layers primarily govern the electrical behavior: the amorphous Ge–chalcogenide active layer that is adjacent to the bottom electrode and the overlying metal–chalcogenide source layer. In this work, we investigate how the variation in the chalcogen species in these two layers influences switching characteristics in the pre-write regime, both in the pristine state and after a write/erase cycle, as well as the conduction behavior at room temperature. The devices were fabricated using Ge-rich chalcogenides containing O, S, Se, or Te, combined with SnS, SnSe, or Ag₂Se metal–chalcogenide layers. The DC current-voltage measurements were analyzed using the standard linearization approaches to examine whether the transport behavior in the pre-write regime exhibits characteristics that are associated with Ohmic, Schottky, Poole–Frenkel, or space charge limited conduction. These measurements specifically probe the pre-write region of the I-V curve, where early ionic redistribution and structural rearrangement precede the abrupt formation of the conductive channels responsible for the resistive switching. The results show that the chalcogen composition strongly affects the threshold voltage, the resistance window, and the onset of field-enhanced transport, reflecting the differences in ionic distribution and channel formation dynamics. The results indicate that transport evolves with a bias and a compliance current, transitioning between regimes that are influenced by the interface injection and bulk-limited conduction, depending on the material stack. These findings clarify the role of chalcogen chemistry in governing the SDC switching behavior and provide guidance for the material selection in application-specific device design. Full article

Homopolymer addition is a widely used strategy to dilate the microdomain spacing of block copolymers, yet the attainable dilation is often limited by macrophase separation in conventional blends at elevated homopolymer loading. In this work, we investigate an architectural route to suppress macrophase separation while retaining homopolymer-driven dilation: a covalently hybridized bottlebrush copolymer (CH-BBC), a copolymacromer-like bottlebrush architecture in which symmetric AB diblock side chains and A-type homopolymer side chains are covalently grafted to a common backbone. Using dissipative particle dynamics (DPD) simulations, we directly compare the phase behavior of CH-BBC melts with that of composition-matched blends of symmetric AB diblocks and A-type homopolymers. Across the explored window, CH-BBC exhibits microphase morphologies and disorder without an observable two-phase region, whereas the corresponding blends show extensive two-phase coexistence at elevated homopolymer loading. Lamellar analysis and one-dimensional density decompositions further reveal that CH-BBC enables substantially larger microphase dilation and stronger selective swelling of the A-rich domain because tethered A-type homopolymer segments preferentially occupy and dilate the A-rich domain interior while diblock A segments remain localized near interfaces. Full article