Search Results (2,847)

This work investigates the NiTi shape memory alloys fabricated via laser powder-directed energy deposition (LP-DED). The properties of NiTi alloys produced by powder metallurgy or additive manufacturing routes are strongly influenced by the type of feedstock material employed. Two powder feedstocks were used for DED fabrication: a blended mixture of elemental nickel and titanium powders with a nominal chemical composition of Ni56Ti44 (wt.%) and a pre-alloyed NiTi powder containing 55.75 wt.% Ni. Samples fabricated from both types of powders were subjected to microstructural characterization, phase composition analysis, and mechanical and corrosion testing. It was found that DED processing on a non-preheated CP-Ti substrate is prone to warping and that samples deposited from the elemental Ni and Ti powder mixture exhibited pronounced inhomogeneity of microstructure and mechanical properties along the build direction, accompanied by the formation of the Ti₂Ni secondary phase. The absence of a superelastic plateau was observed in the corresponding stress–strain response. On the contrary, the samples deposited from the pre-alloyed NiTi powder exhibited a microstructure composed of B2 and B19′ phases and already demonstrated a clear superelastic response in the as-built condition during tensile loading. Based on the tensile test results, this NiTi material was used only for superelasticity testing. The superelastic behavior was further enhanced by post-deposition heat treatment, which significantly increased the recovery rate from 53% to 89%. Full article

Grounded in knowledge recombination theory and innovation tension theory, this study develops a novel measurement framework for scientific and technological innovation (STI) risks that captures the dynamic and systemic equilibrium between novelty and adaptation. We first analyze the endogenous mechanisms through which STI risks emerge from knowledge recombination processes, and then propose a classification framework for knowledge recombination, along with quantifiable metrics for novelty and adaptation. Next, we introduce a risk classification system for STI and corresponding quantitative evaluation metrics, facilitating dynamic monitoring of innovation risk states. Finally, we validate the framework through an empirical case study in natural language processing (NLP). Our results reveal a persistent innovation tension within the STI system between novelty and adaptation. Emerging phrases and reinforced phrases demonstrate distinct risk profiles and distribution patterns, corresponding to differentiated structural and evolutionary regimes. These differences stem from their distinct mechanisms in the novelty–adaptation interaction within a complex innovation system. Specifically, in emerging phrases, novelty shows a stable positive linear correlation with Z-score, while adaptation exhibits a significant negative linear correlation with Z-score. In reinforced phrases, novelty displays a significant bimodal association with Z-score, and adaptation demonstrates a robust inverted U-shaped relationship with Z-score. Emerging knowledge combinations show significantly higher risk scores than reinforced combinations, with high-novelty–low-adaptation combinations consistently in the highest risk quantile across stages. Moreover, the risk threshold for emerging phrases increases monotonically across developmental phases. Thus, our framework advances innovation risk assessment from static categorization to dynamic, system-level evaluation, enabling tiered risk management and optimized resource allocation for high-potential innovation pathways. Full article

Tea cultivar genotype plays a critical role in shaping rhizosphere microbiome assembly, yet the underlying mechanisms remain poorly understood. This study employed a controlled pot experiment with five widely cultivated Chinese tea cultivars (Camellia sinensis) to investigate how cultivar-specific variation influences rhizosphere microbial communities and their assembly processes. Rhizosphere soil microbiomes (bacterial and fungal communities) and metabolomes were characterized using 16S rRNA and ITS2 amplicon sequencing combined with untargeted metabolomics. Significant differences in rhizosphere metabolite composition, primarily organic acids, fatty acids, and carbohydrates, were observed among cultivars, which corresponded to distinct bacterial and fungal community structures. Redundancy analysis (RDA) revealed that rhizosphere metabolites explained 19.87% of bacterial and 21.63% of fungal community compositional variation, second only to soil physicochemical properties. Neutral community model and modified stochasticity ratio analyses indicated that microbial assembly across cultivars was predominantly deterministic, and rhizosphere metabolite profiles were strongly correlated with microbial community structure. Notably, arbuscular mycorrhizal fungi made up about 11% of the fungal communities in minimally fertilized pot systems, contrasting sharply with their near-absence in conventionally managed systems plantations. These findings demonstrate that tea cultivar genotype significantly shapes rhizosphere microbiome assembly through metabolic differentiation, providing a theoretical foundation for integrating microbiome considerations into tea breeding programs and developing cultivar-specific management strategies. Full article

It is a common phenomenon that the stairs of modern historical brick–timber buildings cannot meet existing fire protection specifications, something which has become a difficulty in their renovation. In response, this study proposes two different renovation strategies for the Hui-shaped Chinese Baroque brick–timber building in Harbin and constructs multiple fire scenarios. Using a coupled PyroSim–Pathfinder (version 2023.2.0816) simulation approach, a finite element model of the building under fire and a corresponding evacuation model are established. The aim is to investigate how variations in stair width, number, position, and overall building scale under the two renovation strategies influence evacuation movement time and the number of evacuation failures, and to compare the effectiveness of common fire protection measures. The results show that, for the same stair configuration and building mass, the fire development patterns of the two renovation strategies are similar. Increasing the stair width from the original 0.9 m to 1.1 m produces no significant improvement in evacuation performance. When the number of indoor existing stairways increases from one to two, the proportion of occupants evacuated safely rises from 68% to 91%. External corridor staircases provide the best evacuation performance, and a single such stair can satisfy the safe evacuation of all occupants. When the same additional floor area is provided, increasing the number of storeys extends the evacuation movement time by approximately twice that caused by increasing the building footprint. Automatic sprinkler systems and mechanical smoke exhaust systems exhibit more pronounced fire protection effects. Full article

The Mun River Basin, the largest Mekong tributary in Northeast Thailand, has experienced extensive agricultural expansion and forest decline, raising concerns over increasing soil erosion and sediment transfer. This study provides an integrated assessment of soil loss, sediment yield (SY), and sediment delivery ratio (SDR) across 19 sub-watersheds using the Universal Soil Loss Equation (USLE), field-based SY data, and multivariate statistical analyses in 2024. Basinwide soil loss was estimated at ~35 million t y⁻¹ (mean 4.96 t ha⁻¹ y⁻¹), with more than 80% of the basin classified in the no erosion to very low erosion classes. Despite substantial hillslope erosion, only 402,405 t y⁻¹ of sediment reaches the river network, corresponding to a low SDR of 1.15%, which falls within the range reported for large tropical watersheds with significant reservoir infrastructure. Soil loss is most strongly influenced by slope and forested terrain, while SY responds primarily to rainfall and tree plantations; urban land, croplands, and reservoirs act as sediment sinks. Principal Component Analysis (PCA) resolved multicollinearity and produced six components explaining over 90% of predictor variance. A PCA-based regression model predicted SY per unit area with high accuracy (r = 0.81). The results highlight the dominant roles of hydroclimate and land-use structure in shaping sediment connectivity, supporting targeted soil and watershed-management strategies. Full article

To address the difficulty of controlling surrounding rock subjected to repeated repair-induced disturbances, the characteristics of the roadway surrounding rock and its deformation–failure mechanisms were examined. An experimental scheme for surrounding-rock control was formulated, and a three-dimensional numerical model was established. Four support schemes were evaluated to identify a rational support method and corresponding parameters: (a) rock bolts and cable bolts; (b) rock bolts, cable bolts, and floor cable bolts; (c) rock bolts, cable bolts, floor cable bolts, and U-shaped closed steel sets; and (d) rock bolts, cable bolts, floor cable bolts, U-shaped closed steel sets, and grouting. Comparative analyses were conducted in terms of plastic-zone evolution, stress-field distribution, surrounding-rock displacement, and the mechanical response of the support structures. The results indicate that, in roadways experiencing multiple repair disturbances and supported only by rock bolts and cable bolts, distinct stress-concentration zones develop within the supported surrounding rock, suggesting that reliance solely on bolts and cables is unfavorable for effective rock-mass control. Grouting improves the overall integrity and self-bearing capacity of the surrounding rock. Both the U-shaped closed support and the combined U-shaped closed support with grouting effectively restrain surrounding-rock deformation, and the corresponding stress distribution shows no pronounced stress-concentration zones. Based on the analyses of surrounding-rock displacement, support-structure loading, and incremental shear strain, the effectiveness of the support schemes in mitigating roof and floor displacement ranks, in descending order, as (d), (c), (b), and (a). Engineering practice further demonstrates that the combined support system consisting of 29U-type sets, grouted bolts, and bundle-type grouted cable bolts provides effective control over the deformation and failure of the roadway surrounding rock. Full article

This paper presents a dual four-port circularly polarized (CP) MIMO antenna based on substrate integrated waveguide (SIW) technology for sub-6 GHz applications. The design consists of two identical four-port SIW-based CP-MIMO antennas arranged in a mirror-symmetric configuration with an air gap of 15 mm. Each antenna employs four symmetrically arranged cross-shaped SIW patches excited by coaxial probes. Bidirectional radiation is achieved by applying a 180° phase difference between corresponding ports of the mirror symmetric configuration, referred to as the Backward-Radiating Unit (BRU) and the Forward-Radiating Unit (FRU). The bidirectional radiation mechanism is supported by array-factor-based theoretical modelling, which explains the constructive and destructive interference under phase-controlled excitation. To ensure high isolation and stable polarization performance, the antenna design incorporates defected ground structures, inter-element decoupling strips, and vertical metallic vias. Simulations indicate an operating band from 5.1 to 5.4 GHz. Measurements show a −10 dB bandwidth from 5.25 to 5.55 GHz, with the frequency shift attributed to fabrication tolerances and measurement uncertainties. The antenna achieves inter-port isolation better than −15 dB. A 3 dB axial-ratio bandwidth is maintained across the operating band. Measured axial-ratio values remain below 3 dB from 5.25 to 5.55 GHz, while simulations predict a corresponding range from 5.1 to 5.4 GHz. The proposed configuration achieves a peak gain exceeding 4 dBi and maintains an envelope correlation coefficient below 0.05. These results confirm its suitability for CP-MIMO systems with controlled spatial coverage. With a physical size of 0.733λ₀ × 0.733λ₀ per array, the proposed antenna is well-suited for vehicular and space-constrained wireless systems requiring bidirectional CP-MIMO coverage. Full article

This study presents a diffraction analysis of two semi-submersible platform configurations intended for floating offshore wind turbine applications. The first investigated configuration corresponds to a semi-submersible barge with a central moonpool, while the second configuration is a cross-shaped semi-submersible. Both hydrodynamic models were developed and analyzed in OrcaWave. Simulations were performed for wave incidence directions ranging from 0° to 360°. The obtained hydrodynamic coefficients provide insights into the added mass, radiation damping, load response amplitude operators (RAOs) and two types of mean drift loads RAO of both platform types. The results highlight the influence of geometry and displacement on the diffraction performance, which is critical for the design of floating wind turbine support structures. Full article

To address the depletion of shallow coal resources, mining activities have progressed to greater depths, where rock masses contain numerous fractures due to complex geological conditions, making grouting reinforcement essential for ensuring stability. Using digital image correlation, this study investigated the strain evolution characteristics of grouted fractured specimens of three rock types—mudstone, coal–rock, and sandstone—under uniaxial compression. Analysis of the strain evolution process focused on two typical fracture inclinations of 0° and 60°, while examination of the peak strain characteristics covered five inclinations, namely 0°, 15°, 30°, 45°, and 60°. The findings indicate that the mechanical response varies systematically with lithology and fracture inclination. The post-peak curves differ significantly among rock types: coal–rock shows a gentle descent, mudstone exhibits a rapid strength drop but higher residual strength, and sandstone is characterized by “serrated” fluctuations. The failure mode transitions from tensile splitting at a horizontal inclination of 0° to shear failure at inclinations of 15°, 30°, 45°, and 60°. Strain nephograms corresponding to the peak stress point D reveal sharp, band-shaped zones of strain localization. The maximum principal strain exhibits a non-monotonic trend, first increasing and then decreasing with increasing inclination angle. For grouted coal–rock and sandstone, the peak values of 47.47 and 45.00 occur at α = 45°. In contrast, grouted mudstone reaches a maximum value of 26.80 at α = 30°, indicating its lower susceptibility to damage. The study systematically clarifies the strain evolution behavior of grouted fractured rock masses, providing a theoretical basis for evaluating the effectiveness of reinforcement and predicting failure mechanisms. Crucially, the findings highlight mudstone’s role as a high-integrity medium and the particular vulnerability of horizontal fractures, offering direct guidance for the targeted grouting design in stratified rock formations. Full article

Structures or chemical engineering facilities can be subjected to the combined effects of sulfate corrosion and high temperature in the event of fire. This paper presents experimental results on compressive stress–strain relationships of recycled coarse aggregate concrete (RAC) and normal aggregate concrete (NAC) after dry–wet cycles of sulfate corrosion and high-temperature exposure. First, RAC and NAC specimens were subjected to 0, 20, 40, 60, 80, 100, and 120 dry–wet cycles of sulfate corrosion, respectively. Then, RAC and NAC specimens were subjected to 0 °C, 200 °C, 400 °C, 600 °C, and 800 °C temperature exposures, respectively. At last, RAC and NAC specimens were loaded by uniaxial compressive test. The test results show that the shapes of the stress–strain curves of RAC and NAC specimens after the 200 °C exposure and dry–wet cycles of sulfate corrosion were basically the same as those at room temperature. When the temperature was in the range of 200–400 °C, the elastic modulus and peak stress of RAC decreased with the number of dry–wet cycles of sulfate corrosion, while the corresponding peak strain gradually increased. When the temperature was lower than 400 °C, the number of dry–wet cycles of sulfate corrosion had a greater impact on the peak strain of RAC, while the temperature had a greater impact on the peak strain of RAC when the temperature exceeded 400 °C. After the temperature exceeded 400 °C, the elastic part in the ascending section of the stress–strain curve of RAC gradually shortened, and the peak point of the curve also shifted significantly to the lower right. The increase in peak strain of the RAC was larger than that of NAC. Based on the test results, a compressive stress–strain relationship model of RAC after sulfate corrosion and high temperature is established. Full article

Background: Microplastics (MPs; <5 mm) are pervasive contaminants that can compromise freshwater wetland integrity and wildlife health, yet field evidence from inland systems and non-invasive biomonitoring remains limited. To address this gap, we provide a non-invasive, feces-based baseline for a key wintering waterbird in an inland soda-lake wetland of Türkiye, supported by polymer confirmation. Methods: We evaluated MP occurrence in fecal deposits of the Greylag Goose (Anser anser), a key wintering waterbird at Lake Erçek (Eastern Anatolia, Türkiye), using non-invasive sampling across five periods (October 2024–February 2025). We collected 400 fecal deposits and pooled them into five time-specific composite samples. Accordingly, temporal comparisons are presented descriptively at the composite (period) level rather than as individual-level statistical inference and quantified suspected MPs by type, shape, size, and color; a representative subset (>300 µm; ~20%) was polymer-confirmed by FT-IR, and particle surfaces were examined by SEM–EDX. Results: In total, 959 suspected MP items were recovered, corresponding to an estimated 1.75–2.85 items per fecal deposit (composite-derived; mean 2.40). MP counts peaked in late autumn–early winter (Time 2–Time 3) and declined toward late winter (Time 5). Fibers predominated (37.22%), followed by fragments (30.55%) and pellets (18.77%); the most frequent size class was 100–300 µm (30.25%), and white/transparent particles were most common (38.52%). FT-IR identified polystyrene, polyethylene, and polyvinyl chloride, while SEM–EDX indicated weathered polymeric surfaces. Conclusions: These findings provide baseline evidence of MP exposure in an inland wetland waterbird and support feces-based monitoring for comparative assessments. Full article

Erythrocyte aging is a fundamental physiological phenomenon that involves significant structural and nanomechanical alterations of the cells’ structure and function. Coupling optical, fluorescence, and Atomic Force Microscopy (AFM), we analyzed morphology, membrane roughness and nanomechanical properties of the very same RBCs arising from favism subjects, measured at different stages of their aging in vitro. We also investigated the evolution and abundance of vesicles arising from the cells over their senescence pathway. This approach combines high-resolution fluorescence imaging with the correlation of membrane topology and biomechanics. This explores the differences between investigation based on statistical morphometric parameters, such as membrane roughness, and those based on the measure of point-dependent nanomechanical properties. Our ultra-morphological study evidences the existence of clear differences in the aging of normal and favism erythrocytes that results in a larger number of cells with abnormal shapes and in a hyper-production of vesicles along the senescence pathway of favism cells. In explaining these differences, we focused on the roles played by the hemoglobin evolution and by the morpho-mechanical properties that are responsible for the skeletal alterations. In particular, our data reported evidence that the two corresponding degradative pathways are coupled and play an important enhancement role in promoting the progression of cell senescence. Full article

As a vital ecological security barrier and climate regulator in northwestern China, the spatial patterns and evolving formation mechanisms of ecosystem services within the Qinghai Lake basin hold significant strategic value for ecological conservation and national park development in the region. This study selected land use data during 2000–2020, integrating the equivalent factor method, spatial correlation analysis, and the geodetector approach to systematically investigate the spatial heterogeneity characteristics of ESV in the Qinghai Lake basin and its corresponding driving mechanisms. The results indicate the following: (1) During the period 2000–2020, grassland consistently constituted the primary land cover category within the Qinghai Lake Basin, accounting for over 60% of the total area; water bodies (16.67%) and unused land (16.56%) represented the secondary land use categories. Over this twenty-year period, the total ESV exhibited a slight increasing trend, rising from USD 30.30 × 10⁸ to USD 30.75 × 10⁸, representing a growth of 0.31%. Regulating services constituted the primary component of ESV. The highest contribution to ESV originated from water bodies, with grassland ranking second. (2) ESV displayed a spatial arrangement marked by “high values in the lake center and low values in the surrounding areas” and “higher values in the southeast and lower values in the northwest.” Its spatial correlation exhibits a pronounced positive relationship. The number of units classified as high-high clusters (primarily water bodies at low elevations) and low-low clusters (mainly grasslands and unused land at high elevations) both increased over the study period, indicating a continuous intensification of ESV spatial agglomeration. (3) Results from the geographical detector reveal that both natural and anthropogenic factors collectively drive the spatial variation in ESV, with natural factors exhibiting stronger explanatory capacity. Among these, elevation and temperature are identified as the dominant drivers of ESV spatiotemporal differentiation. The combined effect of two interacting factors surpasses the influence exerted by any single factor in isolation. This research clarifies that the spatial distribution of ESV in the Qinghai Lake Basin, which features “high values in the lake center and low values in the surrounding areas” as well as “higher values in the southeast and lower values in the northwest,” is jointly shaped by the combined control of vertical zonality governed by topographic and climatic factors and the spatial differentiation of human activities. In low-altitude lakeshore zones, ESV rose as a consequence of water body expansion and the enforcement of ecological conservation measures, leading to the emergence of high-value clusters. In contrast, ESV improvement in high-elevation regions remained limited, constrained by fragile natural conditions and minimal human intervention. The insights derived from this research offer a scientific foundation for refining the “one core, four zones, one ring, multiple points” functional zoning framework of the Qinghai Lake National Park, as well as for developing tailored management approaches suited to distinct elevation-based regions. Full article

Background and Objectives: Keratoconus is a bilateral but often asymmetric ectatic corneal disease characterized by progressive thinning, increased curvature, and conical shape of the cornea. Previous studies have reported that the use of swimming goggles in patients with keratoconus can lead to increased intraocular pressure (IOP) and a transient reduction in anterior chamber volume (ACV), potentially affecting anterior segment morphology. This study aimed to evaluate the short-term effects of periorbital pressure induced by swimming goggles on corneal parameters in keratoconic eyes. Materials and Methods: A total of 44 eyes of 44 patients (mean age: 26.1 ± 5.1 years) diagnosed with keratoconus Stage 1–4 according to the Amsler–Krumeich classification were included. Measurements were taken using a Pentacam^® Scheimpflug camera before swimming goggle application and immediately after 20 min of wear. The parameters assessed included keratometry values (K1, K2, Km, Kmax), central and thinnest corneal thickness, corneal volume within the 10 mm zone (CV10), ACV, anterior chamber depth (ACD), iridocorneal angle (ICA), and pupil diameter (PD). Results: No statistically significant changes were observed in keratometric values, central and thinnest corneal thickness, ACV, ACD, ICA, PD, or IOP (all p > 0.05). CV10 showed a small reduction following goggle wear (Δ = −0.18 mm³, corresponding to a 0.3% decrease), which was statistically significant in the unadjusted analysis (p = 0.008) but did not remain significant after correction for multiple comparisons (p for false discovery rate [FDR] = 0.10). Conclusions: Short-term swimming goggle use may induce subtle reductions in CV10 in keratoconic eyes, suggesting a potential biomechanical sensitivity to transient periocular pressure. Although the observed change in CV10 did not retain statistical significance after multiple-comparison correction, it may reflect an early physiological response in structurally compromised corneas. CV measurements could serve as exploratory indicators of mechanical responsiveness in keratoconus, warranting further investigation in larger controlled studies. Full article

This study investigates the dynamic behaviors of re-entrant unit-cell-shaped steel frames through numerical and experimental modal analyses. Inspired by re-entrant honeycomb structures, individual frame units were modeled to explore how natural frequencies vary with beam cross-sectional dimensions and frame angles. Twenty distinct frame models—incorporating four cross-sectional sizes (4 × 4 mm, 8 × 8 mm, 12 × 12 mm, and 16 × 16 mm) and five main frame angles (120°, 150°, 180°, 210°, and 240°)—were developed using 3D modeling and finite element analysis (FEA) tools, and the first eight natural frequencies and corresponding mode shapes were extracted for each model. The results reveal that lower modes exhibit global bending and torsional behaviors, whereas higher modes demonstrate increasingly localized deformations. It is found that the natural frequencies decrease in the straight frame configuration and increase in the hexagonal configurations, highlighting the critical influence of the frame geometry. Increasing the cross-sectional size consistently enhances the dynamic stiffness, particularly in hexagonal frames. A quadratic polynomial surface regression analysis was performed to model the relationship of the natural frequency with the cross-sectional dimension and frame angle, achieving high predictive accuracy (R² > 0.98). The experimental validation results were in good agreement with the numerical results, with discrepancies generally remaining below 7%. The developed regression model provides an efficient design tool for predicting vibrational behaviors and optimizing frame configurations without extensive simulations; furthermore, experimental modal analyses validated the numerical results, confirming the effectiveness of the model. Overall, this study provides a comprehensive understanding of the dynamic characteristics of re-entrant frame structures and proposes practical design strategies for improving vibrational performance, which is particularly relevant in applications such as machine foundations, vibration isolation systems, and aerospace structures. Full article