Search Results (5,329)

Advancements in solid rocket propulsion have intensified the demand for higher specific impulse. Incorporating high-density, high-calorific metal additives into propellant formulations offers a viable pathway to meet these performance targets. Nevertheless, the ablation response of C/C-SiC thermal protection systems (TPS) exposed to high-temperature, high-velocity, dense gas-particle flows remains inadequately characterized. To address this, we employ high-fidelity numerical simulations to resolve the gas-side ablation behavior under extreme multiphase conditions. By calibrating against experimental data, we quantify the erosive mechanisms induced by boron-laden exhaust plumes and derive an empirical correlation for the linear ablation rate. This model serves as a predictive tool for TPS design in severe operational environments. Parametric investigations were conducted across three key variables: particle diameter (30–50 μm), condensed-phase mass loading (28–68%), and impact angle (18–27°). Validation against ground testing yielded a mean deviation of 3.87%, confirming its applicability to the conditions studied in this paper. Results indicate a positive correlation between ablation rate and particle concentration, impact velocity, incident angle (within the tested range), and particle size. During sensitivity analyses, a single-variable control protocol was enforced to isolate individual parameter effects. Full article

Humanoid robots are highly susceptible to structural damage during irrecoverable falls due to high landing velocity, short impact duration, and high peak impact force. Inspired by human protective strategies, namely instinctive postural adjustment and soft-tissue energy absorption, this paper proposes a passive–active cooperative fall-protection method that combines pre-impact motion regulation with post-impact structural energy absorption. On the passive protection side, high-risk contact regions are identified through multi-directional fall simulations, and a multi-region, multilayer protective suit is optimized considering impact energy absorption, peak-force reduction, anti-bottoming safety, added mass, and thickness constraints. On the active protection side, a variable height inverted pendulum (VHIP) model is used to optimize the center of pressure and center of mass trajectories, reducing the terminal impact energy before ground contact. The residual impact energy is then matched with the absorption capacity of the passive protective layers, forming a unified framework that integrates pre-impact motion unloading and post-impact energy absorption. Numerical validation is performed on a MATLAB–CoppeliaSim co-simulation platform, and physical experiments are conducted on the FCR humanoid robot (approx. 50 kg, 1.65 m, 22 DOF). Compared with the unprotected case, the proposed method reduces the peak equivalent impact force from 4819.1 N to 1038.2 N, i.e., a reduction of 78.5%, demonstrating its effectiveness in attenuating impact loads and enhancing protection capability. Full article

Commercial truck path tracking is strongly affected by large mass and yaw moment of inertia, steering-rate constraints, and signal delays, whereas optimization-based predictive controllers can impose high online-computational costs. This study proposes a real-time path-tracking method based on Constraint-Handling Trajectory Prediction (CHTP). A dynamic model predicts the vehicle’s future pose, and a Stanley-based tracking law computes the desired steering angle from the predicted state. A constraint-handling module then explicitly limits the steering angle and its rate of change. The proposed CHTP method requires no online optimization. The method was evaluated through MATLAB/Simulink-TruckSim co-simulations and hardware-in-the-loop (HIL) tests. Under the low-speed unladen condition, CHTP reduced the maximum absolute-displacement error by 74.60% compared with the conventional Stanley controller. Under the high-speed unladen, low-speed heavy-load, and high-speed heavy-load conditions, CHTP completed the lane-change maneuver with bounded tracking errors, whereas the conventional Stanley controller failed to maintain convergent tracking. Across the four basic path-tracking conditions, the maximum absolute displacement and heading errors of CHTP did not exceed 0.3930 m and 0.1133 rad, respectively. Although nonlinear model predictive control (NMPC) generally achieved higher tracking accuracy, CHTP reduced the mean solution time by 94.17–95.96% relative to NMPC, with a maximum solution time of 1.1416 ms. Additional robustness tests showed that CHTP maintained bounded tracking errors and stable lateral dynamic responses under positioning errors, low road adhesion, and random response delays, while preserving its real-time computational performance. In the HIL test with a total loop delay of approximately 0.22 s, extending the prediction time from 0.20 s to 0.42 s limited the maximum displacement and heading errors to 0.2290 m and 0.1046 rad, respectively, with a maximum solution time of only 0.9895 ms. Additional prediction-time tests showed a trend consistent with the simulation results, further supporting the proposed delay-compensation mechanism. These results demonstrate that CHTP provides a favorable balance among tracking accuracy, robustness, and real-time performance. Full article

Large deformation is one of the most critical hazards in tunnels excavated under complex geological conditions. It often causes significant economic losses and threatens construction safety. For layered soft rock tunnels subjected to high in situ stress, the deformation and failure mechanisms are largely governed by the bedding dip angle. To clarify these mechanisms and optimize the corresponding construction control measures, this study investigates a carbonaceous slate section of a railway tunnel in the Western Sichuan Plateau. Field monitoring and FLAC3D numerical modelling are coupled. The influence of the bedding dip angle on the plastic-zone evolution and the failure modes of the surrounding rock is analysed. The micro-bench, three-bench, and reserved core soil methods, together with the rock bolt length, are comparatively evaluated. On this basis, a differentiated reinforcement strategy is proposed for bedding-induced asymmetric loading. The results indicate that: (1) The bedding dip angle governs the failure mode of the surrounding rock. Under the micro-bench method, the plastic zone in subvertically bedded rock masses exhibits a quasi-symmetrical distribution along the normal direction of the bedding planes. The sidewalls predominantly undergo flexural failure. In contrast, under bedding-induced asymmetric loading, the plastic zone concentrates at the left springline and right shoulder. An asymmetric composite failure mode is formed, characterized by shallow flexural–tensile cracking and deep-seated interlayer shear. (2) Under the subvertical bedding condition (89°), the reserved core soil method mitigates the excavation-induced unloading disturbance most effectively. It achieves the lowest peak stress and the smallest tunnel convergence, which is 15.7% and 33.0% lower than those of the micro-bench and three-bench methods, respectively. Its plastic zone reaches full numerical convergence. The reserved core soil method is therefore identified as the optimal excavation Scenario under this condition. (3) The rock bolt length exhibits a threshold effect on deformation control. The most substantial improvement occurs when the bolt length is increased from 4 m to 6 m, beyond which the benefit tends to plateau. A bolt length of 6 m is therefore recommended as the best-performing Scenario among the tested values (4, 6, 8, and 10 m) for the investigated geological and support conditions. For surrounding rock subjected to bedding-induced asymmetric loading, a differentiated reinforcement strategy targeting the vulnerable zones reduces the maximum deformation by 18.8% and 28.3% compared with the uniform reinforcement Scenario and the baseline Scenario, respectively. These findings provide practical insights into excavation-method selection and support optimization for layered soft rock tunnels under similar conditions. Full article

This systematic review and meta-analysis investigated resisted sled training (RST) efficacy compared to unresisted sprint training (UST), alongside the moderating effects of sprint distance, sled load, and surface. Following PRISMA guidelines, PubMed, Web of Science, Scopus and SPORTDiscus were searched up to May 2026. Risk of bias was assessed via the PEDro scale. Twelve studies (N = 324) were included. Data were analyzed using Correlated Robust Variance Estimation (CRVE). Overall, RST reduced sprint times compared to UST (Hedges’ g = −0.250, p = 0.046; I2 = 0.0%). While time reductions were significant for early acceleration (≤10 m; g = −0.360, p < 0.001), and not for longer-distance outcomes (>10 m; g = −0.168, p = 0.293), the between-distance interaction was non-significant (p = 0.094). Moderate loads (g = −0.352, p = 0.062) and indoor gym floors (g = −0.495, p = 0.096) showed larger point estimates than natural grass (g = −0.180) and synthetic tracks (g = −0.197). In conclusion, no statistically significant moderating effects of distance, load, or surface were demonstrated. Because training surfaces influence the actual mechanical stimulus, prescribing sled loads based on velocity decrement (%Vdec) rather than percentage of body mass (%BM) is a promising hypothesis to standardize resistance across terrains, requiring confirmation via future prospective trials. PROSPERO: CRD420261415365. Full article

Arterial hypertension is the leading driver of hypertensive heart disease (HHD), the cardiac structural or functional injury attributable to sustained pressure overload, which promotes left ventricular hypertrophy and provides the substrate for incident heart failure, especially heart failure with preserved ejection fraction (HFpEF). Antihypertensive pharmacotherapy lowers blood pressure (BP) and regresses hypertrophy, yet residual cardiovascular risk persists, and exercise training may add to what drug therapy achieves. HHD progresses through interwoven autonomic, vascular, structural, and diastolic mechanisms, and the benefits of training are uneven across them: functional capacity, BP, endothelial function, and autonomic indices improve within typical trial durations, whereas resting diastolic indices, left ventricular mass, and myocardial fibrosis markers change inconsistently. Carotid–femoral pulse wave velocity is itself sensitive to distending pressure, so a fall does not by itself establish structural arterial remodeling. Small hypertensive trials support favorable geometry, and animal models support antifibrotic mechanisms, but in predominantly hypertensive HFpEF cohorts, capacity gains often occur without durable resting diastolic reversal or mortality benefit. By pairing each hypertension-specific mechanism with the corresponding human evidence, the present narrative review concludes that exercise training is a beneficial adjunct to antihypertensive therapy and to broader risk-factor management, while reverse remodeling and clinical-event reduction remain incompletely proven. Phenotype-guided trials with sensitive imaging, exercise-load endpoints, and hard outcomes are needed. Full article

Improving nitrogen (N) use efficiency while reducing environmental losses remains a major challenge in crop production. Zeolites, due to their high cation exchange capacity, have been proposed as carriers for ammonium-based fertilizers, potentially modifying N retention and release in soils. However, the effect of varying ammonium-loaded zeolite application rates, while supplying equal amounts of zeolite-derived nitrogen, on soil N dynamics is not well understood. In this study, a greenhouse pot experiment with spring wheat was conducted to investigate the effects of ammonium-loaded zeolite applied at different rates (30, 36, 42 and 48 g pot⁻¹; Zeo30–Zeo48), each supplying 700 mg zeolite-derived N pot⁻¹ in addition to a basal ammonium sulfate application, on N leaching, plant growth and N recovery. Nitrogen leaching was strongly influenced by the amount of zeolite applied. Lower application rates (Zeo30 and Zeo36) resulted in higher nitrate and ammonium leaching losses, particularly during early growth stages, whereas higher application rates (Zeo42 and Zeo48) significantly reduced total N losses. Despite these differences, total aboveground plant N uptake and N recovery (68–71%) did not differ significantly among treatments. However, increasing zeolite application rates tended to improve grain and straw yields and influenced nitrogen partitioning within the plant, as reflected by differences in grain-to-straw N ratios. Residual soil ammonium decreased with increasing zeolite application rate, indicating differences in ammonium retention and release among zeolite treatments. Overall, the results indicate that under the conditions of this greenhouse pot experiment, the amount of zeolite carrier material influenced nitrogen retention patterns and leaching losses. Together, these findings suggest that the effectiveness of ammonium-loaded zeolite depends on the balance between ammonium loading and zeolite mass, although the absence of an equivalent mineral-N control limits the separation of zeolite effects from effects of total N supply. Full article

Large hydrocarbon fields are being developed in northern Sakhalin, whereas southern Sakhalin contains prospective resources hosted in unconventional, low-permeability siliceous source rocks. Their development requires stimulation to create conductive fracture networks, whose long-term integrity is critical for production feasibility. This study investigates permeability changes in four artificially fractured specimens subjected to cyclic confining pressure; the specimens are treated as case studies rather than as a statistically representative formation-scale data set. Cylindrical cores, 30 mm in diameter and approximately 30 mm long, containing an induced axial fracture were hydraulically tested under biaxial cyclic confinement. The tests showed irreversible loss of fracture conductivity, with residual permeability after unloading amounting to 7.1–37.4% of the initial value. Direct application of laboratory data to field scale fracture longevity models is inappropriate because cylindrical specimens develop nonuniform circumferential stresses and heterogeneous closure. A procedure is proposed to transfer core scale measurements to a planar fracture subjected to uniform normal stress in the rock mass. Fracture aperture was quantified by X-ray computed tomography (CT) and incorporated into a cell-based contact–hydraulic model accounting for geometric and hydraulic aperture. A nonuniform closure function was used to reconstruct the closure field and correct the laboratory results. At maximum pressure, Kmass/Klab ranged from 0.034 to 0.93 for the three specimens reproduced with acceptable fit; sample 3–4 was retained only as a diagnostic case because of its high root-mean-square error (RMSE). These values are model-based single-fracture scenario estimates pending direct-normal-loading validation. Full article

Bariatric surgery is the most effective treatment for severe obesity, leading to significant and sustained weight loss and improvement in metabolic comorbidities. However, it is also associated with substantial changes in body composition and nutritional status, including the risk of sarcopenia and sarcopenic obesity. This review aims to summarize current evidence on the interplay between metabolic and bariatric surgery, nutritional alterations, and skeletal muscle health. The recent literature highlights a high and increasing prevalence of muscle loss after surgery, driven by reduced protein intake, micronutrient deficiencies, hormonal changes, and decreased mechanical loading. Despite these challenges, improvements in metabolic health and physical function are often observed, suggesting a complex relationship between muscle mass and functional outcomes. A multidisciplinary approach, including nutritional optimization and structured exercise interventions, is essential to mitigate muscle loss and function and improve long-term outcomes. Further research is needed to standardize diagnostic criteria and develop targeted strategies for prevention and management. Full article

Microplastic remediation strategies often overlook the management and valorization of the recovered waste, limiting their overall sustainability. Herein, we propose a closed-loop water remediation strategy in which polyethylene terephthalate microplastics (MicroPET) are not only removed from water but also converted into new magnetic nanomaterials for subsequent remediation cycles. MicroPET was initially harvested using magnetic iron oxide nanoflowers (NFs) and subsequently depolymerized by neutral hydrolysis, achieving an unscaled gravimetric PET mass conversion of 97%. Upon process scale-up and downstream purification, an isolated monomer yield of 28.7% was obtained for both purified terephthalic acid (TPA) and ethylene glycol (EG), as confirmed by ¹H-NMR, FTIR, Raman, and osmometric analyses. The recovered supernatant from the unscaled hydrolysis was directly reused as the reaction medium for the microwave-assisted synthesis of maghemite magnetic iron oxide nanoparticles (MIONPs), producing bimodal single-core nanoparticles composed of 5 ± 1 and 29 ± 6 nm crystallites. Despite the absence of the multicore nanoflower architecture and the associated reduction in magnetic performance, the synthesized nanoparticles still demonstrated a remarkable MicroPET harvesting capacity of 1000 mg g⁻¹ under optimized conditions (compared with 10,000 mg g⁻¹ achieved by the original NFs). Furthermore, both the pristine nanoparticles and the MicroPET-loaded hybrid materials efficiently catalyzed methylene blue degradation through a heterogeneous Fenton-like process, with alternating magnetic field activation increasing the decolorization efficiency by ≈20% compared with room-temperature conditions. These results demonstrate that PET-derived EG can be directly reintegrated into the synthesis of functional magnetic nanomaterials, establishing a circular strategy that combines pollutant removal, plastic waste valorization, and catalytic water remediation. Full article

Background and Objectives: Abnormal plantar pressure distribution is an important biomechanical risk factor for diabetic foot ulceration in individuals with type 2 diabetes (T2D) and peripheral neuropathy. Although several factors have been linked to increased forefoot plantar pressure, factors associated with the forefoot-to-rearfoot pressure ratio remain unclear. This study aimed to investigate the clinical factors associated with the forefoot-to-rearfoot pressure ratio and peak forefoot pressure in this population. Materials and Methods: This study was a cross-sectional analysis of 84 individuals with T2D and peripheral neuropathy enrolled in a randomized controlled trial. Vibration perception threshold (VPT), passive ankle dorsiflexion range of motion, ankle stiffness, plantar pressure distribution, body mass index (BMI), HbA1c, duration of diabetes, and foot deformities were assessed. Multiple linear regression analyses were performed to identify factors associated with plantar pressure outcomes. Results: The model for forefoot-to-rearfoot pressure ratio explained 51.2% of the variance (adjusted R² = 0.467); ankle stiffness (β = 0.505, p < 0.001), foot deformity (β = 0.194, p = 0.030), and ankle dorsiflexion range of motion (β = −0.363, p = 0.001) were independent predictors. The model for peak forefoot pressure explained 31.4% of the variance (adjusted R² = 0.251); ankle stiffness (β = 0.337, p = 0.002), foot deformity (β = 0.278, p = 0.009), and BMI (β = 0.226, p = 0.029) were independent predictors. HbA1c, diabetes duration, and VPT were not significant in either model. Conclusions: In individuals with T2D and peripheral neuropathy, plantar pressure distribution, particularly forefoot loading, appears to be more closely related to biomechanical and structural factors than to metabolic indicators. These findings suggest that assessment of ankle stiffness, joint mobility, and foot posture may provide clinically relevant information for identifying biomechanical factors associated with unfavorable plantar loading in individuals with T2D and peripheral neuropathy. Full article

A membrane brine concentrator (MBC) can reduce the concentrate volume entering thermal processes for zero liquid discharge (ZLD). Previous LSRRO-based studies have largely focused on high-salinity brines using modified or specifically selected low-salt-rejection membranes. This study examined the extent to which water recovery could be increased in wastewater reclamation using conventional nanofiltration (NF) modules in MBC processes. Two brackish water reverse osmosis (BWRO) modules and two NF modules were tested in 2000–40,000 mg/L NaCl. NE4040-90 provided the best balance between salt-concentrating performance and required pressure. An NF module model was developed using experimentally estimated water permeability, salt permeability, and mass-transfer coefficient. It reproduced permeate concentration and feed pressure with normalized root-mean-square errors of 5.73% and 1.20%, respectively. The developed NF module model was then iteratively coupled with the upstream BWRO simulation to evaluate an integrated two-stage BWRO and three-stage MBC process. Compared with conventional BWRO, the integrated system increased overall recovery from 81.0% to 95.9%, reduced concentrate flow from 32 to 7 m³/h, predicted a final concentrate concentration of 51,396 mg/L, and maintained permeate concentration at 34 mg/L while remaining below the 41.4 bar pressure limit. The reduced concentrate load lowered total specific energy consumption from 4.5 to 1.6 kWh/m³ of wastewater feed under the adopted ZLD assumptions. Conventional NF modules therefore provide a practical option for high-recovery wastewater reclamation toward ZLD. Full article

Ibuprofen- and diclofenac-loaded organobentonites are thermally converted to carbon-decorated bentonites and probed as materials for supercapacitors and peroxide production. TGA shows a ~40% mass loss in an inert atmosphere and a ~2% further reduction in air, with the diclofenac-loaded sample showing slightly higher loss due to less stable surface groups. FTIR and Raman spectroscopies indicate similar surface groups and defect densities in the end materials, which are reflected in similar electrochemical responses. Capacitance values of around 20 F/g are measured when taking the whole mass, bentonite and carbon, into account, rising to a maximum of 805 F/g if only the carbon fraction is taken into account. Rotating ring–disk measurements reveal that the prepared materials show selectivity toward peroxide production when oxygen reduction is probed, reaching a 93% yield, making it an exceptional candidate for peroxide production. Full article

Elevated indoor carbon dioxide (CO₂) represents an underutilized biogenic carbon feedstock. Coupling indoor atmospheric remediation with biological sequestration requires overcoming mass-transfer limitations and culture collapse under high carbon loads. This study empirically evaluated a direct-injection, 2.0 L filamentous Leptolyngbya sp. photobioreactor for continuous indoor CO₂ valorization. A fortified nitrogen medium (4.5 g L⁻¹ NaNO₃) was utilized to sustain high-density proliferation. Initial optimization confirmed that narrow-band Red LEDs (10,000 lux) maximized the Apparent Quantum Efficiency (Φ_CO2) at 1.49 × 10⁻³ mol/mol. During a 20-day continuous trial under 5000 ppm CO₂ sparging, the EPS-rich cyanobacterial matrix resisted acidification, achieving a stationary biomass density of 3.30 g L⁻¹. The system maintained a steady bio-mitigation velocity of ~2120 ppm day⁻¹. Intracellular chlorophyll a peaked at 26.0 mg L⁻¹ on Day 10, before severe optical self-shading induced a 47% photoprotective degradation, defining Day 10 as the optimal biorefinery harvesting threshold. At this peak, dynamic efficiency reached 2.07 × 10⁻³ mol/mol. Projecting these kinetics onto a 50 m³ occupied room confirms that capturing ambient CO₂ requires a working volume of 85–90 L and a spatial footprint of <0.25 m², validating Leptolyngbya sp. as a highly resilient catalyst for decentralized, commercial-scale indoor bioprocessing. Full article

Anticipatory postural adjustments (APA) generate initial center of mass motion during gait initiation and are associated with gait performance. While APA amplitude and duration have been linked to gait speed under single-task conditions, it remains unclear how these relationships are altered when motor control is constrained by cognitive demands. This study aimed to examine the association between APA characteristics prior to gait initiation and gait speed under dual-task conditions with externally paced cognitive load. Thirty-one healthy young adults performed fast walking under single- and dual-task conditions. Gait speed and APA parameters, and first-step range of motion were assessed using inertial measurement units. To examine associations between APA parameters and gait speed, multiple regression analyses were conducted separately for each condition. Longer APA duration was associated with decreased gait speed under both conditions. Greater anteroposterior amplitude of APA was associated with increased gait speed only under the dual-task condition, whereas no such association was observed under the single-task condition. No significant association was observed between cognitive performance and gait speed. These findings indicate that the association between APA characteristics and gait speed differs depending on task demands, suggesting that cognitive-motor constraints may modify the role of anticipatory control in gait performance. Full article