Search Results (227)

TiVCr-based alloys are well-explored body-centered cubic (BCC) materials for hydrogen storage applications that can potentially store higher amounts of hydrogen at moderate temperatures. The challenge remains in optimizing the alloy-hydrogen stability, and several transition elements have been found to support the reduction in the hydride stability. In this study, Ni and Nb transition elements were incorporated into the TiVCr alloy system to thoroughly understand their influence on the (de)hydrogenation kinetics and thermodynamic properties. Three different compositions, (TiVCr)₉₅Ni₅, (TiVCr)₉₀ Ni₁₀, and (TiVCr)₉₅Ni₅Nb₅, were prepared via arc melting. The as-prepared samples showed the formation of a dual-phase BCC solid solution and secondary phase precipitates. The samples were characterized using hydrogen sorption studies. Among the studied compositions, (TiVCr)₉₀Ni₁₀ exhibited the highest hydrogen absorption capacity of 3 wt%, whereas both (TiVCr)₉₅Ni₅ and (TiVCr)₉₀Ni₅Nb₅ absorbed up to 2.5 wt% hydrogen. The kinetics of (de)hydrogenation were modeled using the JMAK and 3D Jander diffusion models. The kinetics results showed that the presence of Ni improved hydrogen adsorption at the interface level, whereas Nb substitution enhanced diffusion and hydrogen release at room temperature. Thus, the addition of Ni and Nb to Ti-V-Cr-based high-entropy alloys significantly improved the hydrogen absorption and desorption properties at room temperature for gas-phase hydrogen storage. Full article

To ensure the inherent safety of fine chemical nitration processes, the nitration reaction of benzotriazole ketone was selected as the research object. The thermal decomposition and reaction characteristics of the nitration system were studied using a combination of differential scanning calorimetry (DSC), reaction calorimetry (RC1), and accelerating rate calorimetry (ARC). The results showed that the nitration product released 455.77 kJ/kg of heat upon decomposition, significantly higher than the 306.86 kJ/kg of the original material, indicating increased thermal risk. Through process hazard analysis based on GB/T 42300-2022, key parameters such as the temperature at which the time to maximum rate is 24 h under adiabatic conditions (T_D24), maximum temperature of the synthesis reaction (MTSR), and maximum temperature for technical reason (MTT) were determined, and the reaction was classified as hazard level 5, suggesting a high risk of runaway and secondary explosion. Process intensification strategies were then proposed and verified by dynamic calorimetry: the adiabatic temperature increase (ΔT_ad) was reduced from 86.70 °C in the semi-batch reactor to 19.95 °C in the optimized continuous process, effectively improving thermal safety. These findings provide a reliable reference for the quantitative risk evaluation and safe design of nitration processes in fine chemical manufacturing. Full article

The disadvantages of traditional strip fertilization technology for corn planting in China include low fertilizer utilization rates, unstable operation quality, and environmental pollution. Therefore, in this study, a synchronous hole fertilization device for corn planting based on real-time intelligent control is designed, aiming to reduce fertilizer application and increase efficiency through the precise alignment technology of the seed and fertilizer. This device integrates an electric drive precision seeding unit, a slot wheel hole fertilization unit, and a multi-sensor coordinated closed-loop control system. An STM32 single-chip micro-computer is used to dynamically analyze the seed–fertilizer timing signal, and a double closed-loop control strategy (the position loop priority is higher than the speed loop) is used to correct the spatial phase difference between the seed and fertilizer in real time to ensure the precise control of the longitudinal distance (40~70 mm) and the lateral distance (50~80 mm) of the seed and fertilizer. Through the Box–Behnken response surface method, a field multi-factor test was carried out to analyze the mechanism of influence of the implemented forward speed (A), per-hole target fertilizing amount (B), and plant spacing (fertilizer hole interval) (C) on the seed–fertilizer alignment qualification rate (Y₁) and the coefficient of variation in the hole fertilizing amount (Y₂). The results showed that the order of primary and secondary factors affecting Y₁ was A > C > B, and that the order affecting Y₂ was C > B > A; the comprehensive performance of the device was best with the optimal parameter combination of A = 4.2 km/h, B = 4.4 g, and C = 30 cm, with Y₁ as high as 94.024 ± 0.694% and Y₂ as low as 3.147 ± 0.058%, which is significantly better than the traditional strip application method. The device realizes the precise regulation of 2~6 g/hole by optimizing the structural parameters of the outer groove wheel (arc center distance of 25 mm, cross-sectional area of 201.02 mm², effective filling length of 2.73~8.19 mm), which can meet the differentiated agronomic needs of ordinary corn, silage corn, and popcorn. Field verification shows that the device significantly improves the spatial distribution of the concentration of fertilizer, effectively reduces the amount of fertilizer applied, and improves operational stability and reliability in multiple environments. This provides technical support for the regional application of precision agricultural equipment. Full article

Ribonucleic acids (RNAs) fold into complex structures that are strongly associated with their biological functions. These can be abstracted into secondary structures, represented as nucleotide sequences annotated with base-pairing information. This abstraction is both biologically relevant and computationally manageable. Comparing and classifying RNA molecules typically relies on these secondary structure representations, which exist in multiple formats. In this work, we introduce TARNAS 1.0, a software tool designed to convert RNA secondary structure representations across multiple formats, including Base Pair Sequence (BPSEQ), Connect Table (CT), dot-bracket, Arc-Annotated Sequence (AAS), Fast-All (FASTA), and RNA Markup Language (RNAML). The tool offers options for retaining or removing comments, blank lines, and headers during the conversion process. These format translation and preprocessing capabilities are specifically designed to support the batch handling of large collections of RNA molecules, making TARNAS well suited for large dataset construction and database curation. Beyond format translation, TARNAS computes three levels of abstraction for RNA secondary structures, namely core, core plus, and shape, as well as a set of statistical descriptors for both primary and secondary structure. These abstraction and analysis features are intended to facilitate the comparison of molecules and the identification of recurring structural patterns, which are essential steps for associating structural motifs with molecular function. TARNAS is available as both a standalone desktop application and a web-based tool. The desktop version supports batch processing of large datasets, while the web version is optimized for the analysis of single molecules. Full article

The distribution of suitable habitats for medicinal plants is affected by climate, soil, land use, and other factors. Arnebiae Radix, an important traditional Chinese medicinal resource in Xinjiang, includes Arnebia euchroma (Royle) I. M. Johnst. and Arnebia guttata Bunge and is at risk of over-exploitation. This study predicted suitable planting areas by integrating habitat and phytochemical suitability using the MaxEnt model and ArcGIS. The AUC values for A. euchroma and A. guttata were 0.977 and 0.952, with TSS values of 0.829 and 0.725, respectively, validating the high accuracy of the prediction model. Under the current scenario, the areas of suitable habitats for A. euchroma and A. guttata were 108,914 and 176,445 km², mainly distributed along the main mountains in Xinjiang. Under future climate scenarios, the suitable habitat area of A. euchroma increased by 11–18%, except in the ssp126-2090s scenario, while the suitable habitat area of A. guttata area decreased by 3–18%. Both species were influenced by land use/land cover and soil available nitrogen content; additionally, A. euchroma was affected by the precipitation in the driest month, and A. guttata by the mean diurnal range. The content of secondary metabolites was positively correlated with habitat suitability, with soil factors contributing 35.25% to the total secondary metabolite content. Their suitable habitats predominantly occur in grasslands (42–82%). As habitat and phytochemical suitability distributions aligned, the eastern and western sides of the northern Kunlun Mountain Pass emerged as key areas for cultivation. This research can provide a scientific foundation for selecting optimal planting regions for the two Arnebia species. Full article

The conservation of biodiversity and the balance between ecological and societal needs are critical but often contested global issues. Wildlife-vehicle collision (WVC) on vital infrastructure, especially linear infrastructure, remains a persistent challenge from policy to practice and poses a serious life-threatening implication to humans and other non-human lives. Addressing this issue effectively requires solutions that provide win-win outcomes from both ecological and societal perspectives. This study critically analyzes a decade of roadkill incidents along Nepal’s longest East-West national highway, which passes through a biologically diverse national park in the western Terai Arc Landscape Area (TAL). Findings are drawn from field-based primary data collection of the period 2012–2022, secondary literature review, key informant interviews, and spatial analysis. The study reveals significant variations in roadkill incidence across areas and years. Despite Bardia National Park being larger and having a higher wildlife density, Banke National Park recorded higher roadkill rates. This is attributed to insufficient mitigation measures and law enforcement, more straight highway segments, and the absence of buffer zones between the core park and adjacent forest areas—only a road separates them. Wild boars (Sus scrofa) and spotted deer (Axis axis), the primary prey of Bengal tigers (Panthera tigris tigris), were the most frequently road-killed species. This may contribute to human-tiger conflicts, as observed in the study areas. Seasonal trends showed that reptiles were at higher risk during the wet season and mammals during winter. Hotspots were often located near checkpoints and water bodies, highlighting the need for targeted mitigation efforts such as wildlife crossings and provisioning wildlife requirements such as water, grassland, and shelter away from the regular traffic roads. Roadkill frequency was also influenced by forest cover and time of day, with more incidents occurring at dawn and dusk when most of the herbivores become more active in search of food, shelter, water, and their herds. The findings underscore the importance of road characteristics, animal behavior, and landscape features in roadkill occurrences. Effective mitigation strategies include wildlife crossings, speed limits, warning signs, and public education campaigns. Further research is needed to understand the factors in driving variations between parks and to assess the effectiveness of mitigation measures. Full article

As a pivotal industrial hub in southwestern China, Kunming City has accumulated abundant industrial heritage resources. Investigating the spatial distribution characteristics and influencing factors of industrial heritage across different districts in Kunming is critical for understanding its historical evolution and current status, and for providing scientific guidance for conservation and sustainable development. From a sustainability perspective, this study selected 80 industrial heritage sites in Kunming as research subjects. Utilizing ArcGIS spatial analysis techniques combined with kernel density estimation, standard deviational ellipse, and Geographical Detector analysis, we systematically visualized the spatial distribution patterns and driving factors. Key findings include that (1) industrial heritage exhibits significant spatial heterogeneity, concentrating primarily in the city center and surrounding areas, forming high-density clusters in Wuhua District, Panlong District, and Haikou Subdistrict, while showing marked disparities among regions; (2) distinct spatial distribution patterns emerge across heritage types—manufacturing heritage clusters in central urban zones, whereas mining heritage disperses in peripheral mountainous areas; and (3) historical preservation policies are identified as the dominant factor shaping the current distribution, whereas terrain and natural environmental impacts remain secondary. These findings offer actionable insights for optimizing the conservation and adaptive reuse of Kunming’s industrial heritage. Full article

Camptotheca acuminata Decne. is an endemic and valuable tree species in China that is renowned for its medicinal and economic value due to secondary metabolites like camptothecin, a potent anti-cancer compound. With wild resources dwindling, it is a key protected species. Predicting and analyzing its suitable habitats under different future environmental scenarios is essential for conservation, introduction, development, and planting strategies. This study used 1008 distribution points and 32 environmental factors, applying the MaxEnt v3.4.4 model and ArcGIS v10.7 software to predict C. acuminata’s potential distribution under four greenhouse gas emission scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) for the present, 2050, and 2070. This study identifies the key environmental factors influencing its distribution and analyzes habitat trends under various ecological scenarios. The dominant environmental factors are Bio6 (contribution 23%; importance 59.8%), human activity factor (contribution 18.6%; importance 15.7%), Slope2 (contribution 1%; importance 7%), Slope3 (contribution 5.1%; importance 3.4%), elevation (contribution 0.9%; importance 1.7%), and Bio14 (contribution 41.2%; importance 1%). The total potential suitable habitat area for C. acuminata is 1.5796 × 10⁴ km². Except under RCP8.5, where the habitat area continuously increases, the habitat area shows a trend of first increasing and then decreasing. When human activity is considered, the total potential suitable habitat area is 1.8495 × 10⁴ km², with a consistent decrease under all scenarios except RCP8.5. Centroid migration analysis shows that, driven by global warming, the suitable habitats for C. acuminata are shifting toward higher latitudes. This study provides theoretical support for the conservation, resource management, and germplasm protection of C. acuminata under future ecological and environmental changes. Full article

The widespread practice of deliberate human displacement for biodiversity conservation remains a contentious issue in the Anthropocene era. This study explores the ecological impacts of conservation-led resettlement (ER) in Nepal’s Terai Arc Landscape (TAL), a biodiverse region under significant conservation and development pressures. Although ER aims to enhance ecological integrity, the role of displacement in conservation has been understudied. Using case studies from the TAL, we examined ecological indicators in vacated settlement areas within parks and newly resettled sites outside protected zones. Data were collected through a review of secondary literature, 240 household interviews, 5 focus group discussions, 25 key informant interviews, and multiple field visits across resettlement sites. Between 1973 and 2019, TAL gained 922.52 sq. km of core protected areas (displacing over 4800 households) and dispossessed communities from 2120.12 sq. km of buffer zones, significantly expanding protected areas and upgrading conservation standards from IUCN category IV to II. This contributed to the recovery of key species such as tigers, rhinos, and elephants. However, resettlements, often located along critical biological corridors and buffer zones, led to habitat fragmentation, endangering the gene pool flow and creating isolated habitats. Results show that, in general, most ecosystem and environmental variables were perceived significantly different (p < 0.05) among resettled communities in the study area. The cultural and land-based attachments of displaced communities were overlooked. These findings highlight the risks of short-term resettlement planning, which can exacerbate pressures on critical corridors, escalate human–wildlife conflicts, and provide a clear indication of the trade-off between conservation benefits and social costs. Full article

A high-porosity micro-arc oxidation (MAO) functional coating was fabricated on aluminum foam substrate through micro-arc oxidation technology, developing a structurally and functionally integrated bulk catalyst support material. Orthogonal experiments were employed to determine the optimal electrical parameters for achieving maximum coating porosity, with systematic investigations into the effects of electrolyte temperature and sodium tetraborate additives on pore characteristics. The phase composition, surface morphology, and elemental distribution of the porous coating were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Mercury intrusion porosimetry was applied to quantify the total pore area and pore size distribution. By means of secondary micro-arc oxidation, the catalyst was distributed in a gradient on the coating cross-section, which greatly improved the utilization rate of the catalyst. The formation mechanism of the porous coating was discussed, and the specific surface area of the fabricated catalyst-loaded materials was as high as (1.4~6.3) × 10⁴ m²/m³, which provided a large number of attachment sites for catalyst particles. Full article

Groundwater plays a leading role in ecological environment protection in semi-arid regions. The Huangshui River Basin is located in the Tibetan Plateau and Loess Plateau transition zone of semi-arid areas. Its ecological environment is relatively fragile, and there is an urgent need for systematic study of the basin to develop a groundwater environment and realize the rational and efficient development of water resources. In this study, methodologically, we combined the following: 1. Field sampling (271 groundwater samples across the basin’s hydrogeological units); 2. Comprehensive laboratory analysis of major ions and physicochemical parameters; 3. Multivariate statistical analysis (Pearson correlation, descriptive statistics); 4. Geospatial techniques (ArcGIS kriging interpolation); 5. Hydrochemical modeling (Piper diagrams, Gibbs plots, PHREEQC simulations). Key findings reveal the following: 1. Groundwater is generally weakly alkaline (pH 6.94–8.91) with TDS ranging 155–10,387 mg/L; 2. Clear spatial trends: TDS and major ions (Na⁺, Ca²⁺, Mg²⁺, Cl⁻, SO₄²⁻) increase along flow paths; 3. Water types evolve from Ca-HCO₃-dominant (upper reaches) to complex Ca-SO₄/Ca-Cl mixtures (lower reaches); 4. Water–rock interactions dominate hydrochemical evolution, with secondary cation exchange effects; 5. PHREEQC modeling identifies dominant carbonate dissolution (mean SIcalcite = −0.32) with localized evaporite influences (SIgypsum up to 0.12). By combining theoretical calculations and experimental results, this study reveals distinct hydrochemical patterns and evolution mechanisms. The groundwater transitions from Ca-HCO₃-type in upstream areas to complex Ca-SO₄/Cl mixtures downstream, driven primarily by dissolution of gypsum and carbonate minerals. Total dissolved solids increase dramatically along flow paths (155–10,387 mg/L), with Na⁺ and SO₄²⁻ showing the strongest correlation to mineralization (r > 0.9). Cation exchange processes and anthropogenic inputs further modify water chemistry in midstream regions. These findings establish a baseline for sustainable groundwater management in this ecologically vulnerable basin. Full article

This study aims to reduce pores, cracks, and other defects on the surface of laser powder bed fusion (LPBF)-fabricated 18Ni300 steel and improve its surface quality. Remelting was carried out on the surface with an argon arc as the heat source. Then, the surface layer was characterized using SEM, EDS, XRD, EBSD, and hardness testing. The results showed the following: When the pulse current $I$ increased from 16 A to 20 A, the surface hardness of LPBF 18Ni300 increased due to a decrease in defects and an increase in the martensite phase. The driving forces of convection in the molten pool (such as buoyancy, Lorentz magnetic force, surface tension, and plasma flow force) rose with an increase in current. When the current $I$ exceeded 20 A, the convection became more intense, making it easier for gas to be entrained into the melt pool, forming pores and introducing new defects, resulting in a decrease in surface hardness. The primary factors affecting the hardness of LPBF 18Ni300 after surface argon arc remelting were pore (defect) weakening and phase transformation strengthening, while the secondary factors included grain refinement strengthening and texture strengthening. The solidification mode of the remelted layer was: L → A → M + A′. The phase transition mode of the heat-affected zone was: M + A′ → A_reverse → M_temper. Compared with the base material and heat-affected zone, the grains in the remelted layer formed a stronger <001> texture with a larger average size (2.51 μm) and a lower misorientation angle. The content of the residual austenite A′ was relatively high in the remelted layer. It was distributed in the form of strips along grain boundaries, and it always maintained a shear–coherent relationship with martensite. Full article

With the acceleration in urbanization, surface hardening has increased, urban flooding and soil erosion problems are frequent, and urban water resource management faces great challenges. Sponge city construction can effectively alleviate these problems by simulating the natural water cycle and constructing blue–green infrastructure. In this study, the analytic hierarchy process (AHP) and the ArcGIS weighted overlay tool were used to construct a framework for assessing the suitability of sponge city construction in Suzhou from the three dimensions of Geo-Smart spatial productive forces, Eco-Dynamic green productive forces, and Resilio-Tech responsive productive forces. A zoning strategy based on new quality productive forces is also proposed. The results show that Suzhou can be divided into three types of construction zones according to the suitability level: key construction zones, secondary key construction zones, and general construction zones. The key construction zones account for about 28.01% of the total land area, mainly covering the built-up areas of Suzhou, covering the developed urban areas such as Gusu District, Xiangcheng, Suzhou Industrial Park, and other key zones such as Northern Kunshan. The secondary key construction area and general construction area, on the other hand, account for 61.94% and 10.05% of the total area, respectively. From the new quality productive forces, this study proposes the following construction guidelines for sponge city zones: (1) enhance the coordinated development of urban planning and sponge city construction; (2) promote blue–green infrastructure development, strengthen inter-departmental cooperation, and ensure ecological and economic co-development; and (3) encourage public participation in governance. This research offers theoretical and practical guidance for sponge city construction in Suzhou and other cities from the perspective of new quality productive forces. Full article

Currently, multi-target survey telescope arrays play an important role in the build-up and maintenance of space object catalog databases, collecting massive observational data without attributing information. However, the matching process of massive observational data poses significant challenges to traditional prediction methods. To address the issues of low matching success rates and prolonged computation times in traditional methods, this paper proposes a multi-threaded data starting point matching method. First, orbital elements from the Space Surveillance and Tracking (SST) database are extracted for two days before and after the observation moment. A set of orbital elements closest to the observation epoch is filtered to form the primary candidate catalog containing the maximum number of objects. A matching error threshold is set. Second, multi-threaded traversal of the primary candidate catalog is performed to calculate observation residuals with the data starting point using an orbit prediction procedure. Orbital elements meeting the triple matching error threshold are selected to form the secondary candidate catalog, which is used in the entire data arc segment-matching calculation. Finally, the root mean square error (RMSE) of observation residuals for the entire data arc segment is computed point by point. The orbital elements satisfying the matching threshold are identified as matching results based on the principle of optimality. Experimental results demonstrate that with a matching error threshold of 1°, the proposed method achieves an average matching success rate of 97.62% for data arc segments with nearly 10,000 passes per day over 8 consecutive days. In the SST database containing an average of 25,720 targets, this method processes an average of 2164 data arc segments per minute, improving matching efficiency by 115 times compared to traditional prediction methods. Full article

In this paper, the D3Q19 multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) for large eddy simulation (LES) was employed to optimize the shape of the vortex generator in a triangular vortex flowmeter. The optimization process focused on the vortex shedding frequency, lift force per unit area, and symmetry of the vortex street. The optimal shape of the vortex generator was determined to feature a 180° incoming flow surface, a concave arc side with a curvature radius of 25 mm, and a fillet radius of 4 mm at the end. Numerical simulations revealed that the optimized vortex generator achieves a 2.72~13.8% increase in vortex shedding frequency and a 17.2~53.9% reduction in pressure drop and can adapt to the flow conditions of productivity fluctuations (6.498 × 10⁵ ≤ Re ≤ 22.597 × 10⁵) in the gas well production. The results demonstrated significant advantages, including low pressure loss, minimal secondary vortex generation, high vortex shedding frequency, and substantial lift force. These findings underscore the robustness and efficiency of the LBM-LES method in simulating complex flow dynamics and optimizing vortex generator designs. Full article