Search Results (8,333)

Isoprene is a significant source of secondary organic aerosol (SOA) in the atmosphere. This study investigates the physicochemical properties of isoprene-derived SOA formed through ozonolysis and photooxidation under varying NO_x conditions in an environmental chamber. SOA produced by dark ozonolysis and under low NO_x conditions had a density of 1.35–1.38 g cm⁻³ and an organic-to-carbon (O:C) ratio of 0.89–0.97. It was relatively volatile, consisting of semi-volatile organic compounds (SVOCs, 40%) and low-volatility organic compounds (LVOCs, 52%), with a small fraction of extremely low-volatility organic compounds (ELVOCs, ~7%); its vaporization enthalpy (ΔH_vap) was 90–106 kJ mol⁻¹. Under high NO_x conditions (isoprene/NO_x ratios = 1.2–6.8, with isoprene units in ppbC), SOA exhibited lower density (1.26–1.29 g cm⁻³) and lower O:C ratios (0.62–0.72). It was also less volatile than SOA formed under dark ozonolysis and low NO_x conditions; volatility decreased with decreasing isoprene/NO_x ratio, while ΔH_vap increased from 65 to 95 kJ mol⁻¹. SOA formed under very high NO_x conditions (isoprene/NO_x ratio = 0.6) was characterized by a higher density (1.34 g cm⁻³) and O:C ratio (0.88). However, it was the least volatile, comprising 68% LVOCs and 32% ELVOCs, and had the highest ΔH_vap of 114 kJ mol⁻¹. At low isoprene/NO_x ratios (0.6–1.2) yields were suppressed (0.6%) in comparison to those (6.8%) at higher isoprene/NO_x ratios (5–7). Full article

In ecologically fragile and geomorphologically complex mountainous regions, ensuring a smooth transition from poverty alleviation to multidimensional sustainable rural development remains a key issue in regional governance. Focusing on the Qinba Mountains, a typical former contiguous poverty-stricken region in China covering 18 prefecture-level cities in six provinces, this study uses 2009–2023 prefecture-level panel data to examine the spatiotemporal evolution and driving mechanisms of coordinated rural revitalization. An integrated framework of “multi-dimensional evaluation–spatiotemporal tracking–attribution diagnosis” is developed by combining the improved AHP–entropy-weight TOPSIS method, the Coupling Coordination Degree (CCD) model, spatial Markov chains, spatial autocorrelation, and the Geodetector. The results show pronounced subsystem asynchrony. Livelihood and Well-being Security (U5) improves steadily, while Level of Industrial Development (U1), Civic Virtues and Cultural Vibrancy (U3), and Rural Governance (U4) also rise but with clear spatial differentiation; by contrast, Quality of Human Settlements (U2) fluctuates in stages under ecological fragility. Overall, the coupling coordination level advances from the Verge of Imbalance to Intermediate Coordination, yet the regional pattern remains uneven, with eastern basin cities leading and western deep mountainous cities lagging. State transitions display both policy responsiveness and path dependence: the probability of retaining the original state ranges from 50.0% to 90.5%; low-level neighborhoods reduce the upward transition probability to 25%, whereas medium-to-high-level neighborhoods raise the upward transition probability of low-level cities from 36.36% to 53.33%. Spatial dependence is also evident, with Global Moran’s I increasing, with fluctuations, from 0.331 in 2009 to 0.536 in 2023; high-value clusters extend along the Guanzhong Plain–Han River Valley corridor, while low-value clusters remain relatively locked in mountainous border areas. Driving mechanisms show clear stage-wise succession. At the single-factor level, the explanatory power of Road Network Density (F6) declines from 0.639 to 0.287, whereas Terrain Relief Amplitude (F1) becomes the dominant background constraint in the later stage (q = 0.772). Multi-factor interactions are generally enhanced. In particular, the traditional infrastructure-led pathway weakens markedly, with F1 ∩ F6 = 0.055 in 2023, while the interaction between terrain and consumer market vitality becomes dominant, with F1 ∩ F7 = 0.987 in 2023. On this basis, three major pathways are identified: government fiscal intervention and transportation accessibility improvement, capital agglomeration and market demand stimulation, and human–earth system adaptation and ecological value realization. These findings provide quantitative evidence for breaking spatial lock-in and improving cross-regional resource allocation in ecologically constrained mountainous regions. Full article

Soil compaction and reduced infiltration capacity are critical constraints limiting soil physical quality and hydraulic functioning in semi-arid vineyard systems subjected to repeated machinery traffic. This study aimed to develop and evaluate a geometry-optimized strip tillage tool designed to improve structural functionality within the compacted root zone while minimizing inter-row disturbance. A U-shaped working body configuration, consisting of two oppositely inclined shanks and a central chisel, was theoretically substantiated and optimized using multifactor analysis. Field experiments were conducted to assess changes in penetration resistance, bulk density, and infiltration rate within the 20–40 cm soil layer under semi-arid conditions. The optimized geometry significantly reduced penetration resistance and bulk density in the trafficked strip, indicating alleviation of mechanical impedance and improved root-relevant physical conditions. Infiltration capacity increased after treatment, indicating enhanced hydraulic continuity within the root zone. Unlike full-width subsoiling, the localized strip intervention preserved inter-row soil stability and limited unnecessary disturbance, which is consistent with conservation-oriented soil management. The results indicate that geometry-optimized strip tillage is associated with improved soil physical quality and hydraulic function within compacted vineyard strips. The operational applicability of the developed implement may also depend on vineyard layout and terrain conditions. The prototype tool was tested under conditions representative of vineyards with standard row spacing and relatively moderate slopes typical for the experimental site. In vineyards with very narrow row spacing, steep slopes, or highly heterogeneous soil conditions, adjustments in working width, shank spacing, or tractor–implement configuration may be required. Future studies should therefore investigate the performance of the optimized geometry under contrasting vineyard configurations, including steep hillside vineyards and high-density planting systems. By linking implement design to quantitative soil structural and hydraulic indicators, this study contributes to the development of vineyard soil management practices for semi-arid perennial cropping systems. Full article

This study presents a comprehensive multi-parameter analysis of seismo-ionospheric responses to the Mw 7.7 Myanmar earthquake on 28 March 2025, using GNSS-based Total Electron Content (TEC) data, seismic b-value trends, and acoustic gravity wave (AGW) signatures. A significant negative TEC anomaly (~30 TECU below the statistical threshold) was detected on 25 March, three days before the mainshock under geomagnetically quiet conditions, indicating a lithospheric origin. Concurrent variations in the Ionospheric Disturbance Index (IDI) and Rate of TEC Index (ROTI) indicate pronounced background departures and enhanced short-term variability during the preparation phase. Temporal b-value analysis shows a consistent decline from 1.12 to 0.58 across the 30-year to 6-month windows, with the lowest values clustering near the epicenter, indicating progressive stress accumulation. Spatial b-value mapping further reveals a low b-value zone overlapping the region of TEC depletion, while the Relative Seismic Hazard Index (RSHI) highlights high-hazard zones aligned with the epicentral area. Kernel density estimation (KDE) supports this coupling by showing a dominant low-b, low-vTEC cluster, consistent with linked lithospheric stress and ionospheric depletion. Overall, the integrated GNSS and seismic analyses demonstrate the value of multi-domain observations for characterizing earthquake preparation processes, highlighting a coherent physical linkage between crustal stress accumulation and ionospheric depletion that can enhance short-term seismic hazard assessment. Full article

Objectives: The long-term effects of rheumatoid arthritis (RA) therapies on bone mineral density (BMD) remain incompletely characterized. We aimed to evaluate BMD trajectories over an 8-year follow-up in patients with RA treated with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or biological DMARDs (bDMARDs) in real-world practice. Methods: Patients were selected from an observational RA cohort established at Nice University Hospital between 2001 and 2016. Participants were classified into two groups according to treatment regimen (csDMARD only or any bDMARD exposure). BMD was assessed by dual-energy X-ray absorptiometry at baseline and after 1, 2, 3, 5, and 8 years at the lumbar spine, femoral neck, and total hip. Longitudinal changes in BMD were analyzed using multivariable linear mixed-effects models adjusted for age, sex, body mass index (BMI), disease duration, seropositivity, glucocorticoid use, anti-osteoporosis treatment, and clinical response. Results: A total of 312 patients were included, of whom 181 received bDMARDs and 131 were treated exclusively with csDMARDs. BMD showed limited change during the first two years in both groups. Beyond two years, modest declines were observed at hip sites at subsequent time points, whereas lumbar spine BMD did not demonstrate significant longitudinal change in pointwise analyses. In mixed-effects models, the treatment group–time interaction was significant for lumbar spine (p = 0.004) and total hip (p = 0.04), but not for the femoral neck (p = 0.34), indicating differential BMD trajectories over time between treatment groups. In the csDMARD group, lumbar spine and total hip BMD decreased by a mean of 0.0006 and 0.0005 g/cm² per month, respectively, whereas no significant slopes were observed in the bDMARD group. Older age was associated with lower BMD, while male sex and higher BMI were associated with higher BMD across sites. Conclusions: In this long-term real-world cohort, BMD remained relatively stable during the first two years of follow-up. Longitudinal analyses suggested a less pronounced decline in lumbar spine and total hip BMD trajectories among bDMARD-treated patients compared with those receiving csDMARD alone, underscoring the need for ongoing bone health monitoring in RA. Full article

Hollow auxetic structures enable lightweight mechanical design by reducing mass while preserving architected deformation. However, hollow auxetic studies focus on LPBF metals. This study presents a manufacturing-constrained design and validation framework for a hollow hybrid re-entrant chiral lattice produced by stereolithography. The unit cell was parameterised by chiral angle, re-entrant strut length, and hollow internal diameter, with drainage features integrated into the CAD model to preserve hollow channels during printing and post-processing. A minimum internal diameter study defined the printable design window. Within these limits, a central composite design coupled with finite element analysis mapped the response surface and identified an optimised geometry of θ = 15°, L = 3.5 mm, and d = 1.68 mm, with a predicted unit-cell negative Poisson’s ratio of about −1.17. Compression testing confirmed that the printed unit cell and 3 × 3 × 3 lattice retained the intended rotation-dominated auxetic deformation mode. At the selected comparison strain, the unit cell showed a negative Poisson’s ratio of −0.68 and the 3 × 3 × 3 lattice showed −0.29. Relative to the solid lattice, the hollow lattice reduced density by 42.4% with only a 3.0% reduction in stiffness, increasing specific stiffness by 68.9% and specific peak strength by 5.2%, but reducing specific energy absorption by 25.6% due to earlier localisation and junction driven fracture. These results provide practical design guidance for manufacturable hollow SLA auxetic lattices, especially for lightweight and stiffness-limited applications where low mass and high specific stiffness are more important than energy absorption. Full article

Rising urban temperatures have become a critical constraint to urban ecosystem resilience and livability due to rapid urbanization. This study proposes a novel intra-city zoning scheme, named component morphological blocks (CMBs), which classifies built-up areas into six types characterized by multidimensional urban canopy morphologies. The XGBoost-SHAP model, optimized via Bayesian tuning, was employed to examine the relative contributions of 16 potential driving variables to block-scale land surface temperature (LST). The results show that: (1) LST gradually increases with increasing building density in the warm seasons. The average building height (BH) exhibits a positive correlation with shaded area, thereby reducing LST on the block scale; (2) hotspots are mainly concentrated in function-oriented blocks with hotspot distribution indices of 1.85, 1.96, 1.24, and 1.14, respectively. Coldspots are largely observed in blue–green space in the warm seasons; (3) BH dominates the LST across seasons, while the building-related factors make a prominent impact on LST in warm seasons. The contribution of vegetation canopy density is followed by BH during autumn and winter (12.2%, 10.9%); (4) a distinct transition occurs between summer normalized difference built-up index (NDBI) and fractional vegetation cover around an NDBI of 0.1. In winter, the interaction between 2D and 3D vegetation factors indicates a shift in their relative contributions from negative to positive as they increase. This study demonstrates that CMBs serve as an effective choice for characterizing LST patterns at the block scale, providing insights for sustainable urban development aimed at mitigating the urban heat island effect. Full article

Multiview video coding grows exponentially with the number of views, and VVC-based systems face particularly severe computational burdens from exhaustive inter-view prediction searches. We propose VVC-MV-CM, a complexity-managed multiview extension of VVC that combines rule-based pre-screening with CNN-based adaptive inter-view prediction bypassing within a two-stage decision engine. Performance trends are observed across 19 test sequences covering planar, arc, and spherical camera configurations under all-view and selected-view encoding modes. For planar all-view configurations, VVC-MV-CM-A achieves −52.7% BD-rate relative to MIV-A with 68% encoding time reduction. Arc arrangements yield competitive performance at −1.26% (all-view) and approximately −1% (selected-view) BD-rate. Spherical configurations demonstrate −19.8% (all-view) and −15.0% (selected-view) BD-rate gains, driven by multi-reference redundancy and temporal prediction prioritization. View density analysis reveals a 4.8 percentage-point compression difference between all-view and selected-view configurations, corresponding to approximately 2.4% efficiency gain per doubling of camera count. The proposed codec achieves 1.17–1.46× encoding time relative to MIV anchors with 18–36% decoding speedup, establishing configuration-adaptive prediction as an effective and deployable approach to multiview video coding across a wide range of geometric complexities and view-sampling densities. Full article

Material extrusion (MEX) additive manufacturing can produce material-dependent variations in dimensional fidelity, internal structure, and deposition stability, even under identical processing conditions. In this study, a comprehensive experimental investigation is conducted on MEX-printed specimens manufactured from a broad set of PLA-based composite materials to quantify these variations and assess their mutual interdependence. Dimensional behavior, internal structural characteristics, and process behavior were systematically investigated using complementary geometric, physical, and deposition-related descriptors. All properties were determined from replicated specimens to ensure statistical robustness, and the resulting datasets were examined using both conventional metrics and multivariate 3D correlation approaches. Compact PLA-based formulations exhibit consistent internal packing, characterized by relative density (RD) values of approximately 0.40–0.46, porosity (ϕ) levels around 55–60%, reduced (≤0.15%) density variability (CV), and small (−0.4–0.0%) volumetric deviations (ΔV). These features reflect stable extrusion and predictable dimensional response. In contrast, foamed, fiber-reinforced, and organic-filled composites display reduced internal packing (RD < 0.40), increased ϕ (>60%), elevated CV (0.27–0.58%), and systematically larger positive ΔV (up to +1.4%), indicating a higher sensitivity to process-induced heterogeneity. Multivariate correlations further reveal that volumetric dimensional distortion is jointly governed by internal packing efficiency and extrusion stability. Overall, the results demonstrate that dimensional accuracy in MEX of PLA-based composites arises from coupled structure–process interactions rather than isolated material or process parameters. The experimental framework proposed here provides quantitative guidance for material selection and process optimization aimed at enhancing geometric fidelity in composite filament fabrication. Full article

This study analyzed seven foliar traits of Cedrela odorata L. (Meliaceae) in 87 individuals across three germplasm movement zones in Tabasco, Mexico (VIII: humid; XIV: intermediate; XXI: dry) to assess differentiation and climatic relationships. Leaf length, area, petiolule length, leaflet number, rachis length, width, and stomatal density were measured. Univariate tests, canonical correlation analysis, redundancy analysis, and a relative phenotypic plasticity index were applied. Significant morphological differentiation was found: zone XIV exhibited the largest leaves and longest rachises, zone VIII the highest stomatal density, and zone XXI smaller, more subdivided leaves. The first canonical axis (r = 0.846, p < 0.001) associated long and wide leaves with warm, humid conditions, while the second (r = 0.810, p < 0.001) linked stomatal density and width to temperature minimum. Climate explained 55.7% of morphological variation, primarily through water and temperature gradients. High plasticity in leaf area, rachis length, and stomatal density suggests adaptive flexibility, yet consistent inter-zonal differences indicate local adaptation. These results demonstrate a strong correspondence with Tabasco’s germplasm movement zones and providing morphological evidence to support reforestation and germplasm management strategies under variable climatic conditions. Full article

Compression–torsion lattice structures (CTLS) exhibit coupled compressive–torsional deformation, yet their response under underwater shock loading remains to be further investigated. In this study, sandwich structures with CTLS cores were investigated through a combination of shock tube experiments, digital image correlation (DIC), and nonlinear finite element analysis. The underwater shock response and protective performance were evaluated based on rear-plate kinetic energy, central deflection, and plastic deformation. The results indicate that, at the same relative density, CTLS sandwich structures reduce the rear-plate kinetic energy by more than 42% and the peak deflection by 12.4%, compared with sandwich structures employing traditional straight lattice structures (TSLS). Under identical compressive stiffness, CTLS provide superior protective performance to TSLS, and this advantage becomes more pronounced with increasing ligament diameter. Furthermore, CTLS sandwich structures extend the tunable range of the core energy absorption ratio from 33–35% to 24–38%, reflecting enhanced flexibility in energy distribution within the structure. Full article

This study elucidates the impact of laser volumetric energy density (VED) on the densification behavior, microstructural evolution, wear resistance, and corrosion resistance of high-Nb TiAl alloys fabricated via laser powder bed fusion (LPBF). Experimental characterization results showed that relative density first increased and then decreased with increasing VED, reaching a maximum density of 97.13% at 66.67 J/mm³. Across the process windows, the high-Nb TiAl alloys were primarily composed of γ-TiAl, α2-Ti3Al, and β/B2 phases with varied proportions. Mechanical property analysis showed that the alloy attained a maximum average hardness of 422 HV_0.5 at 81.48 J/mm³, due to the accumulation of harder α2 and B2 phases. However, the high-Nb TiAl alloys fabricated at 66.67 J/mm³ exhibited excellent wear resistance, as evidenced by wear track widths and depths of 971.71 μm and 21.83 μm, respectively. Abrasive and oxidative wear were identified as the primary mechanisms. Meanwhile, this specimen also exhibited excellent corrosion resistance, a corrosion current density of 1.421 × 10⁻⁶ A/cm², attributed to the coupled dense passive film of TiO₂ and Al₂O₃ that prevented chloride ingress. The findings in this work may provide a critical experimental reference and theoretical underpinnings for LPBF-fabricated lightweight structural materials. Full article

Accessibility indicators derived from web-map platforms are increasingly used in sustainable spatial planning, service allocation, and land-value modelling, particularly in data-constrained regions. Yet the reliability of such source-dependent measures for decision-making remains insufficiently examined. Using paired parcel-level data from Khyber Pakhtunkhwa, Pakistan, this study conceptualizes accessibility as a spatial measurement process with structured source uncertainty by directly comparing platform-derived (PD) and field-verified (FV) nearest-facility distances across five facility types. Cross-source analysis reveals substantial facility-specific discrepancies in both magnitude and rank ordering, with certain facility types exhibiting near-random or reversed parcel rankings between sources. Spatial diagnostics further demonstrate that discordance events are geographically clustered rather than randomly distributed. An exploratory local amenity-density check further shows that mismatch prevalence varies systematically with nearby POI context, although the relationship is heterogeneous rather than uniformly sparse-driven. Under spatial block cross-validation, land-value models using FV accessibility consistently outperform PD-based models, while PD-based models display fold-level instability. Moreover, coefficient sign orientation and relative importance vary systematically across sources, indicating interpretation sensitivity to measurement choice. Importantly, reducing magnitude error alone does not restore decision reliability when ordering instability persists. These findings show that accessibility source choice can reshape spatial prioritization and inferred price gradients, introducing decision risk into sustainability-oriented planning. We therefore propose a minimum reliability protocol—including discrepancy profiling, ordering diagnostics, spatial discordance mapping, and spatially structured validation—to support transparent and defensible accessibility analytics in data-constrained environments. Full article

This study evaluated the effects of different environmental enrichment tools on broiler chickens from 1 to 21 days of age. A total of 120,000 one-day-old broiler chicks were randomly assigned to five treatments, each consisting of four replicates with 6000 birds per replicate. Replicates were housed in pens measuring approximately 362 m². The treatments included: T1, green balls (approximately 40 balls per pen); T2, hanging toys (8–10 toys per pen); T3, hanging strings (8–10 string bundles per pen); T4, rotational use of green balls, hanging toys, and strings at equivalent densities; and T5, a control group without enrichment. Data were collected on growth performance, foot health, behavioral activity, serum biochemical parameters, and carcass and meat quality traits. Birds provided with hanging enrichment tools showed significantly improved growth performance (p ≤ 0.05) compared with the control group. Among enriched treatments, T2 yielded the highest body weight and weight gain, as well as the lowest feed conversion ratio. Enrichment treatments also resulted in significant improvements (p ≤ 0.05) in carcass characteristics and selected meat quality parameters, including lightness (L*) and pH stability. Behavioral observations indicated substantially higher activity levels in enriched groups relative to the control. Toe damage scores differed significantly among treatments (p = 0.004), with the lowest scores observed in T1 and the highest in T4; however, no significant differences were detected in footpad dermatitis or hock burn scores (p > 0.05). In conclusion, hanging environmental enrichment tools, particularly hanging toys, can effectively enhance growth performance, behavioral activity, and selected carcass and meat quality traits in broiler production systems, while their effects on footpad health appear limited under the conditions of this study. Full article

Laser Powder Bed Fusion for metals (PBF-LB/M) is a complex additive manufacturing process in which metal powder is selectively melted layer-by-layer to fabricate 3D parts. Process parameters critically influence the resulting microstructure in nickel alloys, with features such as melt pool marks, grain size and orientation, porosity, and cracks serving as key process signatures. These features are typically analyzed post-process to identify suboptimal conditions. This research aims to develop automated post-process measurement and analysis techniques using image processing, pattern recognition, and statistical learning to correlate process parameters with part quality. Optical microscopy images of build surfaces are analyzed using machine learning algorithms to evaluate porosity, grain size, and relative density in fabricated test coupons. Effect plots are generated to identify trends related to increasing energy density. A novel deep learning approach based on Mask R-CNN is used to detect and segment melt pool regions in optical microscopy images. From the segmented regions, melt pool dimensions—such as width, depth, and area—are extracted using bounding geometry coordinates. Manually labeled images (Type I and Type II) are used to train the model. A comparison between ResNet-50 and ResNet-101 backbones shows that the ResNet-50-based model (Model 2) achieves superior performance, with lower training loss (0.1781 vs. 0.1907) and validation loss (8.6140 vs. 9.4228). Quantitative evaluation using the Jaccard index, precision, and recall metrics shows that the ResNet-101 backbone outperforms ResNet-50, achieving about 4% higher mean Intersection-over-Union, with values of 0.85 for Type I and 0.82 for Type II melt pools, where Type I is detected more accurately due to its more regular morphology and clearer boundaries. By extending Faster R-CNNs with a mask prediction branch, the method allows for precise melt pool measurements, providing valuable insights into process quality and dimensional accuracy, and aiding in the detection of defects in PBF-LB-fabricated parts. Full article