Search Results (8,153)

Non-grain production of cultivated land has increasingly affected regional food security and the stability of agricultural ecosystems. In traditional rice-producing regions, changes associated with non-rice cultivation, fallow land, rice-fishery integrated farming, and intensive agricultural management are reshaping the spatial structure of paddy landscapes. To identify the long-term spatiotemporal evolution of paddy systems, this study investigated Northern Jiangxi, China, using Landsat surface reflectance imagery from 2000, 2005, 2010, 2015, and 2020 on the Google Earth Engine (GEE) platform. The Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) were used to construct a phenology-based Flooding Frequency (FF) indicator. Based on the annual frequency with which pixels satisfied the condition LSWI > EVI, cultivated land was classified into three categories: non-flooded cropland, standard rice paddy, and high-frequency flooded cropland. In this study, non-flooded cropland was used as an indicator of potential non-rice cultivation rather than as direct evidence of confirmed non-grain production. Landscape metrics, transition matrices, gravity center migration, standard deviation ellipses, and geographically weighted regression (GWR) were then used to examine paddy landscape dynamics, fragmentation patterns, and county-level spatial associations with socioeconomic factors. The results suggest that the paddy system in Northern Jiangxi experienced marked stage-based fluctuations between 2000 and 2020. Standard rice paddy recovered during 2005–2010, whereas non-flooded cropland expanded considerably during 2010–2015, accompanied by intensified paddy landscape fragmentation. Non-flooded cropland was mainly distributed around urban fringes, transport corridors, and some hilly margins. Standard rice paddy was concentrated in traditional grain-producing areas, including the Poyang Lake Plain and the Gan-Fu Plain. High-frequency flooded cropland was primarily located in low-lying lake areas, where its dynamics were likely associated with rice-fishery integrated farming, continuous irrigation, and hydrological fluctuations. Landscape metrics showed that the largest patch index and mean patch size of standard rice paddy declined after 2010, indicating reduced spatial continuity of core paddy fields. The GWR analysis provided auxiliary evidence that total population, per capita gross domestic product (GDP), and urbanization rate were spatially associated with changes in non-flooded cropland at the county level; however, the results should be interpreted as exploratory associations rather than causal mechanisms. Overall, paddy landscape change in Northern Jiangxi was expressed not only through changes in cultivated land area, but also through the reorganization of paddy function, spatial continuity, and land-use intensity. Future cropland protection should therefore move beyond area-based control toward integrated management of quantity, quality, function, and spatial configuration. Future research should further verify these findings using dynamic cropland boundaries, higher-resolution imagery, and more detailed socioeconomic data. Full article

Increasing planting density is an effective strategy for improving maize (Zea mays L.) productivity, but it can also intensify interplant competition and canopy shading. Enhanced nitrogen application may help offset these negative effects. A two-year field experiment was conducted in the Hexi Corridor, an arid region of northwestern China, using a full factorial design with three planting density levels D1 (75,000 plants ha⁻¹), D2 (90,000 plants ha⁻¹), and D3 (105,000 plants ha⁻¹), and three nitrogen application levels N1 (198 kg ha⁻¹), N2 (264 kg ha⁻¹), and N3 (330 kg ha⁻¹). The aim was to clarify how the interaction between planting density and nitrogen application regulates maize canopy structure and affects resource use efficiency in arid areas. The results showed that planting density, nitrogen rate, and their interaction significantly affected canopy structure, photosynthetic traits, grain yield, and water and nitrogen use efficiency. From the perspective of each growth stage, combinations of medium and high planting density and nitrogen application levels facilitated the optimization of maize canopy structure, promoted plant growth and dry matter accumulation, and elevated leaf SPAD values. Meanwhile, treatment D2N2 exhibited the most prominent improvement in maize yield components, with grain yield increased by 1.44–35.58% on average across experimental years. This treatment also sustained superior water and nitrogen use efficiency, achieving an average water use efficiency of 3.53 kg·m⁻³ and an average partial factor productivity of nitrogen of 53.41 kg·kg⁻¹. Comprehensive multi-index evaluation verified that D2N2 represented the optimal cultivation regime. This regime could reduce nitrogen fertilizer input by 20% while fully exploiting light and heat resources inherent to arid regions. Collectively, this study establishes a viable green and high-efficiency cultivation paradigm for maize production with high yield, reduced fertilizer input and water conservation, and delivers critical theoretical and technical references for the sustainable intensification of maize cultivation in arid regions of northwest China. Full article

China is rich in magnetite mineral resources, but they are generally characterized by low grade, fine dissemination size, and a high content of harmful impurities. Wet low-intensity magnetic separation (WLIMS) is an important method for processing fine-grained magnetite. However, during the separation process, fine magnetite particles are prone to magnetic agglomeration, which makes it difficult for conventional WLIMS separators to achieve high-selectivity separation. To address this issue, a novel WLIMS separator based on a rotating magnetic system was developed in this investigation, and its separation characteristics were systematically investigated through a combined approach comprising CFD–DEM–FEM multiphysics coupling simulations and experimental validation. Simulation results indicate that the rotating magnetic system significantly reduces the chain length and the structural stability of magnetic agglomerates just as magnetite particles enter the magnetic field region. Furthermore, under the rotating action of the magnetic system, the magnetic chains only enclose a portion of the intergrowth minerals, while gangue minerals remain unattached, which positively contributes to improved separation selectivity. Both laboratory-scale experimental results and industrial production data indicate that, compared to the conventional WLIMS separator, the rotating magnetic system WLIMS separator achieves significantly superior separation performance. For a magnetite ore with a grade of 57.68%, the rotating magnetic system WLIMS separator achieved an optimal concentrate grade of 65.43% (with a recovery of 94.78%), whereas the conventional WLIMS separator attained only 60.32% at a similar recovery rate. This investigation provides an important basis for the large-scale industrial application of rotating magnetic system WLIMS separators and the efficient development and utilization of fine-grained magnetite resources. Full article

Predicting the cytotoxicity of engineered nanoparticles remains a significant challenge due to the vast combinatorial diversity of their physicochemical properties. In this study, we developed a multimodal generative framework to synthesize high-fidelity nanoparticle candidates with predefined toxicity indices. We used a large language model to extract heterogeneous data from scientific articles and utilized SciBERT-based embeddings to encode unstructured textual toxicity summaries. Four generative architectures—CTGAN, TVAE, WGAN-GP, and TabDDPM—were benchmarked using the Synthetic Data Vault quality score. The TabDDPM demonstrated superior performance in capturing complex structure–activity relationships, achieving an SDV quality score of 0.78. The case study validation and feature evolution analysis prove the practical efficacy of the TabDDPM. To validate the physical plausibility of the best generated model, we conducted coarse-grained molecular dynamics simulations in the GROMACS 2026.0 engine using the Martini 3.0.0 force field. Comparative analysis of safe and toxic nanoparticles candidates revealed that the toxic variant induced 2.4 times higher electrostatic stress (88.76 kJ/mol) and significantly prolonged membrane equilibration times. The safe candidates had a lower center-of-mass distance between the nanoparticle and the hydrophobic core of the lipid bilayer compared to the toxic counterpart. These results confirm that the proposed generative approach not only replicates statistical distributions but also captures the underlying biophysical mechanisms of membrane disruption, providing a potentially robust tool for the in silico design of biocompatible nanomaterials. Full article

Defects such as lack-of-fusion pores, keyhole pores, and thermal cracks are inherent to additively manufactured (AM) components and significantly degrade their mechanical performance, yet their quantitative influence on the strength of AM structures remains insufficiently understood. In this study, a columnar-grained microstructure of AM 316L stainless-steel pipe material containing explicit pores and cracks was reconstructed using the Monte Carlo method based on SEM observations and was incorporated into a calibrated crystal plasticity finite element model. The reconstructed columnar-grain width agreed with the measured value, and the predicted yield strengths of both defect-free and defect-containing material matched tensile measurements, confirming the accuracy of the micromechanical framework. Moreover, the influences of the pore diameter, crack length, pore arrangement, and porosity on the circumferential and axial yielding were systematically investigated. Results showed that increasing the size of the pore and porosity reduced the circumferential and axial yield strengths simultaneously with distinct extents. Cracks exhibited pronounced directional sensitivity: circumferential cracks mainly reduced axial capacity, whereas an axial crack reduced circumferential strength significantly, indicating that crack-induced degradation is governed by the interaction between crack orientation and loading direction. Directional pore arrangements produced anisotropic responses, whereas random arrangements reduced this anisotropy and resulted in a quasi-isotropic response, although clustering at higher porosity intensified local stress-concentration interactions and further lowered load-bearing capacity. The results clarify the mechanisms of defect-induced stress concentration and local plastic evolution and provide a quantitative basis for defect-tolerance assessment and quality control of AM components. Full article

Less attention has been paid to soils with potentially toxic elements (PTEs) below agricultural land risk screening values, even though they continue to accumulate these elements. In this study, four typical areas in Ningxia were selected to determine the concentrations of cadmium (Cd) and arsenic (As) in 176 samples collected from 130 sampling sites across seven matrices. A refined mass balance model was developed by partitioning irrigation input into suspended-solid and supernatant phases and crop removal into grain and straw components. The model was used to analyze the contributions of various input and output factors and to predict future soil Cd/As concentrations and their related health risks via soil exposure. The input fluxes of Cd and As in the four regions ranged from 1.31 to 3.25 g·ha⁻¹·yr⁻¹ and 71.43 to 146.99 g·ha⁻¹·yr⁻¹, respectively, mainly contributed by irrigation water (40~64%), especially suspended solids in irrigation water, and atmospheric deposition (23~40%). The output fluxes of Cd and As were 0.89~1.43 g·ha⁻¹·yr⁻¹ and 13.81~33.86 g·ha⁻¹·yr⁻¹, respectively, dominated by crop harvesting (36~82%). The differences in input and output fluxes were mainly caused by the regional industrial structure and agricultural planting structure. The predicted results showed that soil Cd and As concentrations in all regions would not exceed regulatory limits after 100 years in the current scenario. A health risk assessment based on soil ingestion, dermal contact, and inhalation showed that the hazard indices for Cd and As were negligible, but their total carcinogenic risk reached notable levels. Over time, Cd-specific carcinogenic risk for children increased in several scenarios and transitioned from negligible to notable risk, with soil ingestion being the dominant exposure pathway. According to the results, targeted mitigation strategies, including the regulation of atmospheric deposition, optimization of irrigation water quality, and adoption of straw off-field practices, show potential to effectively limit the accumulation of potentially toxic elements in agricultural soils. Full article

This study develops a workflow for forest carbon accounting in the West Qinling Mountains, China (2000–2025), integrating CLCD data, key-year forest subtype mapping, and InVEST-style carbon pools. Forest subtypes were classified with Random Forest under spatial block cross-validation (overall accuracy = 59.76%, Cohen’s Kappa = 0.3974, Macro-F1 = 0.5944). Under the baseline workflow, total carbon stock increased from 876.40 to 954.45 million Mg C, yielding a net gain of 78.05 million Mg C (+8.91%). The Hamed–Rao modified Mann–Kendall test identified a significant increase (Sen’s slope = 2.41 million Mg C year⁻¹, $p=2.99\times {10}^{-5}$). A bounded parameter sensitivity analysis produced a 2025 total carbon range of 887.07–1021.84 million Mg C, whereas Scheme A yielded a more conservative net gain of 60.19 million Mg C. County-level patterns were broadly similar across scenarios, but fine-grained ranking remained uncertain. Because the annual series is a hybrid product, with annual forest/non-forest updates but a subtype structure refreshed only at key years, the results should not be interpreted as an independently reconstructed annual record of subtype transitions. The workflow therefore provides an uncertainty-aware regional accounting framework rather than a fully observed annual reconstruction of historical forest composition. Full article

Nano-priming has emerged as a novel technology for improving seed germination, vigour, and stress tolerance, and enhancing nutrient uptake in cereal grains, especially rice and wheat. This study presents a bibliometric analysis of 6302 publications obtained by a Boolean search query from the Scopus database, executed in November 2025. The dataset was further refined by using strict inclusion–exclusion criteria and mapped for the intellectual, geographic, and collaborative structure of the research on the topic under study at the global level. Country-level research productivity, subject-area distribution, annual publication trajectories, source-level publication patterns, and co-authorship networks are part of this study. The analysis revealed a highly skewed global publication distribution dominated by China, India, and Pakistan, which are major global hubs for nanotechnology-assisted seed treatment research, on the nano-priming of seeds. Agricultural sciences, environmental sciences, materials science, and nanotechnology emerged as dominant interdisciplinary contributors to nano-priming research. Annual publication trends continue to show an exponential rise since 2013, driven by growing interests in nanotechnology-enabled crop improvement. Co-authorship analysis revealed dense collaborative clusters centred in South and East Asia, interconnected through key bridging authors. The bibliometric evaluation, together with evidence-based synthesis of experimental studies, highlighted zinc oxide, titanium dioxide, silver, iron oxide, chitosan, and carbon-based nanomaterials as the main hotspots driving physiological enhancement in rice and wheat through enzymatic activation, nutrient uptake, and stress-resilience pathways. Nanotechnology-based seed treatments in rice and wheat offer a promising and sustainable approach to enhance crop productivity, stress tolerance, nutrient-use efficiency, and global food security under changing environmental conditions. Full article

The scientific community and engineers are interested in simulating and analysing the behaviour of individual components and complex structures. This review article highlights progress in the area of modelling of structural materials based on the use of the finite element method. In addition to being described deterministically, the situation ahead of a possible stress concentrator is also defined using modern statistical techniques, and the behaviour simulation is explained in terms of length scales. Crack development and generation in the component are the main uses of the description of the impact of local microstructure on macrostructure. There are two predominant types of multiscale analysis: hierarchical and concurrent. Hybrid types also exist, but these are beyond the scope of this paper. Mainly, two-scale hierarchic simulations are illustrated hereafter. The modelling is dedicated to the following groups of materials: (i) crack initiation around inclusions, carbides at grain boundaries, and natural or artificial stress concentrators; (ii) composites with short or long fibres and pronounced interfaces; and (iii) combinations of (i) and (ii) in the case where the grain structure behaves like a short fibre. The authors draw on many years of experience in the field of numerical methods and, in particular, the modified finite element method. Full article

Aluminum metallic foams are lightweight porous materials characterized by low density, high stiffness, and remarkable energy absorption capacity. The mechanical performance of these materials strongly depends on the microstructure of the metallic matrix and the porous structure. In this study, closed-cell A356 aluminum foams were produced by the Alporas melt-foaming method using barite (BaSO₄) as a thickening agent and calcium carbonate (CaCO₃) as a foaming agent. The effect of grain refinement on the microstructure and energy absorption behavior under quasi-static compression was investigated. Grain refinement was evaluated by adding four concentrations of Al-5Ti-1B master alloy (0.02, 0.05, 0.08, and 0.10 wt.%) to the unrefined foam. The addition of Al-5Ti-1B reduced the secondary dendrite arm spacing (SDAS) from 41.85 µm to a minimum of 32.96 µm at 0.05 wt.%, producing stronger and more homogeneous cell walls that increased the plateau stress from 0.525 to 1.549 MPa and the energy absorption capacity from 0.299 to 0.735 MJ/m³—improvements of 195% and 145%, respectively. The energy absorption efficiency analysis confirmed that any refiner concentration improved the compressive performance compared to the unrefined foam. In addition, the energy absorption efficiency (E) and the ideality energy absorption efficiency (I) confirm that the refinement of the dendritic structure through Al-5Ti-1B addition strengthens the foam cell walls, improving their mechanical behavior and performance as an energy-absorbing material under quasi-static compression. Full article

In this study, pure hydroxyapatite (HAp) was successfully produced by using eggshells. The eggshells were collected locally and calcined to get CaO from them. The CaO powder was reacted with diammonium hydrogen phosphate in a mechanochemical method using attritor milling. A portion of the synthesized samples was subjected to a second calcination process at 900 °C to investigate the thermal effects on the material. The structures of the samples were investigated by scanning electron microscopy, X-ray diffraction, and infrared spectroscopy. The as-prepared HAp appeared to be nanocrystalline with low-intensity reflections, which transformed into a highly crystalline hexagonal phase after heat treatment, as revealed by XRD analysis. Quantitative analysis revealed the thermal evolution of the secondary Ca(OH)₂ phase, due to the thermal decomposition into CaO without causing HAp decomposition into tricalcium phosphates. FTIR analysis showed characteristic phosphate bands for both samples, but the calcined sample displayed sharper peaks and a clear loss of residual water and carbonates. SEM observations also highlighted the major morphological transformation. The highly aggregated as-prepared nanoparticles formed larger, well-defined grains. Notably, the calcined sample also exhibited a rough, textured surface with a macroporous network with interconnected channels. EDS analysis confirmed a Ca-P-O-rich composition, where the elevated Ca/P ratio (Ca/P = 2.28) suggested the presence of secondary calcium-rich phases. These structural, chemical, and morphological characteristics suggest that eggshell-derived HAp, with or without a second heat treatment, has high potential and may be optimized for different applications in bone tissue engineering. However, biological performance was not evaluated in this study. Full article

During the service of solid rocket motors, propellant grains need to bear various loads such as curing cooling, gravity, and combustion internal pressure. The internal pore defects will seriously affect the structural integrity. In this paper, a three-dimensional finite element model of propellant–insulation layer–mold is established to study the structural responses of pore defects with different sizes (30–100 mm) under three typical working conditions: curing cooling, curing cooling coupled with gravity, and internal pressure loading. It is found that under the curing cooling condition, compared with the non-porous propellant grain structure, the structure with pores will raise the overall mechanical response of the propellant grain, and the maximum stress and strain are mainly concentrated in the front end of the core hole and the wing groove area. The pore size has a limited impact on the overall stress distribution, but will change the local stress concentration degree. Among them, the 80 mm pore reduces the stress in the wing groove area through stress field interference. Moreover, large-size pores will significantly weaken the structural bearing capacity and increase the contact pressure between the propellant and the core mold. Under the condition of curing cooling coupled with gravity, the stress and strain are mainly distributed at the edge of the pores, and the values increase with the increase of pore size. Under the action of internal pressure load, the stress and strain in the middle section of the propellant grain have no obvious change, but stress concentration occurs in the transition area between the core hole and the wing groove and at the end of the wing groove. The results of this study provide a reference for the integrity evaluation and structural optimization of propellant grains with pore defects. Full article

Delayed floor water inrush can be triggered during deep coal seam mining in Northern China under the coupled effects of Ordovician limestone confined aquifers and fault structures. Taking a typical working face threatened by a confined aquifer as the engineering background, this study investigates the hydraulic erosion-induced instability of fault fracture zone fillings and the formation mechanism of water-conducting pathways by integrating compositional analysis of fault-zone fillings, laboratory seepage tests, and numerical simulations. The results show that the fault fillings are dominated by fine-grained clay minerals, mainly including kaolinite, illite, illite–smectite mixed-layer minerals, and montmorillonite. Under mining-induced disturbance and confined water pressure, these fillings are prone to pore-structure reconstruction and permeability enhancement. The seepage process in the fractured rock mass exhibits pronounced non-linearity and can be divided into three stages: initial seepage, abrupt seepage transition, and stable seepage. The migration and loss of fine particles are the key factors controlling the formation of water-conducting pathways and the increased risk of water inrush. As the fracture-zone width increases, fault dip angle and aquifer water pressure all enhance fault water-conducting capacity, promote the upward migration of confined water along the fracture zone, and aggravate the risk of floor water inrush at the working face. The research achievement can provide an important reference for elucidating and controlling floor water-inrush mechanisms in confined-aquifer working faces affected by faults in similar engineering conditions. Full article

This study investigates the environmental potential and viability of replacing natural river aggregates (RAs) with copper slag aggregates (CSAs) in concrete production. The primary objective was to assess the structural performance of these eco-concrete mixtures and determine the optimum copper slag content for structural applications. The experimental program evaluated concrete mixtures with natural river aggregate replacement levels of 20% + 20% and 50% + 100% for the 8/16 mm and 16/32 mm fractions, respectively, using coarse copper slag aggregate (CCA). The results indicate that incorporating CCA increases concrete compressive strength, successfully meeting the requirements for strength class C25/30. The petrographic assessment indicated a shift towards an aggregate mixture, in which the dominant quartzite and a constant quartz-mineral fraction of 16.5% provide a stable structure alongside the CSA grains. However, a significant increase in water penetration depth (up to 22%) was observed, highlighting the enhanced water penetration depth of these concretes. SEM microstructural analysis attributed the improved bond between the cement matrix and CCA grains to a compact interfacial transition zone. Additionally, leaching tests confirmed that heavy metals are effectively immobilized in the cement paste for mixtures with lower replacement levels (up to 20%), thereby meeting environmental standards. The study concludes that copper slag at these controlled replacement levels represents a sustainable, high-quality alternative for construction materials in drainage infrastructure. Incremental analysis in accordance with NEN 7375 showed that the tested material behaves as an insoluble matrix, with no evidence of diffusion-controlled leaching. The cumulative leaching values obtained after 64 days of testing in accordance with NEN 7375 were significantly below the regulatory limits for all components analyzed. These findings indicate a low potential for contaminant release and favorable environmental stability of the 20% replacement mixture, though further leaching evaluation is required for maximum slag contents. Full article

This study explores the potential of non-destructive methods for diagnosing timber structures, with a primary focus on maximising the capabilities of the resistance-drilling technique. Laboratory tests were performed on spruce wood specimens, the most commonly used construction timber in Central Europe, prepared across a wide range of moisture contents (0–53%) to assess the influence of moisture on resistance-drilling characteristics. The resistance micro-drilling (RM) characteristic was found to be independent of moisture content (coefficient of determination close to zero), confirming that resistance drilling provides stable results under varying in situ moisture conditions. In contrast, wood density and the RM characteristic were strongly correlated, with coefficients of determination of R² = 0.87 for moisture contents between 0% and 30%, and R² = 0.90 for the 8–18% moisture range typical of timber in service. Based on these relationships, two linear conversion equations were developed (ρ = 1.685·RM + 183.85 and ρ = 1.982·RM + 135.15, respectively), enabling estimation of spruce wood density directly from RM values. Compressive strength parallel and perpendicular to grain decreased with increasing moisture content up to the fibre saturation point, beyond which the reduction in strength plateaued. Full article