Search Results (23,380)

Wood-based particleboards are a key component of sustainable building materials due to their renewable and low-carbon nature. However, their susceptibility to microbial contamination poses a significant challenge to indoor environmental quality and durability, limiting their alignment with the principles of a healthy and circular built environment. In this study, a sustainable antibacterial modification strategy was developed by employing natural montmorillonite (MMT) as a renewable mineral carrier to address the challenge. A synergistic antibacterial agent (Cu²⁺/ZnO@MMT-O) was engineered via ion exchange and co-precipitation, effectively immobilizing Cu²⁺ ions and ZnO nanoparticles within the MMT structure. This process preserved the layered structure of the carrier while simultaneously enhancing its specific surface area and mesoporosity. Antibacterial tests revealed that the Cu²⁺/ZnO@MMT-O exhibited markedly higher antibacterial activity against Escherichia coli and Staphylococcus aureus than single-component counterparts, indicating a pronounced synergistic effect. At an additive loading of 1.25%, the particleboards exhibited antibacterial rates exceeding 99% against both tested bacteria, while their mechanical properties (MOR 10.65 MPa, MOE 2304.40 MPa, and IB 0.29 MPa) and dimensional stability (24 h TS 16.31%) compliant with national standards. Overall, this work presents a practical and sustainable approach to enhancing the hygienic performance of renewable wood composites through the integration of mineral carriers with synergistic nanoscale antibacterial mechanisms, thereby contributing to healthier indoor environments and the development of green and healthy residential materials. Full article

Hydrogen embrittlement poses a critical threat to the durability of metallic components in emerging hydrogen energy infrastructure. Reliable fatigue life assessment in hydrogen-rich environments is, however, severely constrained by the high cost and low throughput of high-pressure testing, resulting in characteristically sparse experimental datasets. Conventional empirical fatigue models struggle to capture hydrogen–mechanical coupling effects, while purely data-driven approaches often suffer from severe overfitting under data-scarce conditions. To address this challenge, this study develops a physics-enhanced learning framework that integrates established fracture mechanics principles with machine learning. Using high-strength GS80A steel as a case study, two complementary strategies are introduced. First, a physically augmented input strategy reformulates raw experimental variables into dimensionless physical descriptors derived from the Basquin and Goodman relations, thereby reducing the complexity of the learning space. Second, a physics-regularized ensemble strategy combines deterministic physical predictions with neural network outputs through a dual-pathway inference scheme, ensuring physically admissible behavior during extrapolation. An automated hyperparameter selection module is further employed to establish a robust data-driven baseline. Comparative evaluation against optimized multi-layer perceptron and support vector regression models demonstrates that the proposed framework significantly improves predictive robustness in small-sample regimes. Specifically, the coefficient of determination (R²) exceeds 0.975, with the root mean square error (RMSE) reduced by approximately 70% compared to the pure data-driven baseline. By systematically embedding mechanistic priors into the learning process, the proposed approach provides a reliable and interpretable tool for fatigue assessment of metallic components operating in hydrogen environments. Full article

This paper investigates the impact of tubed propeller design on the energy efficiency and acoustic emissions of sub-250 g quadcopters. This study was motivated by the growing popularity of ultralight UAVs and the lack of experimental data addressing the trade-offs between noise, efficiency, and mass. Ten drone configurations with varying tube geometries and tip clearances were constructed using 3D-printed PLA+ frames and identical propulsion components. Experimental tests were conducted in a reverberation room to measure sound pressure levels and onboard energy consumption during hover. The results show that tubed configurations are 3–6.5 dB louder than untubed ones, with a noticeable shift toward higher frequencies. While tubes increased total power demand by 18–37% compared to the lightest design, they also reduced it by 3–17% relative to untubed drones of the same mass. The findings demonstrate that tubing improves aerodynamic efficiency only under same mass constraints and is most beneficial when mechanical protection is prioritized over noise and endurance. Full article

This study examines the political dilemma in tourism governance in Mandalika, Indonesia, focusing on three key components: accountability, transparency, and resource allocation. This research aims to reframe the role of political activity to align with the principles of community benefit and justice. Data collection was conducted through a survey from August to September 2025, with 465 questionnaires distributed. A total of 444 questionnaires (95.48%) were deemed valid, while 21 (4.52%) did not meet the criteria and were excluded from the analysis. Data were analyzed through Microsoft Excel and SmartPLS version 4.1.1. The results show that a serious political problem leads to less freedom in how things are managed, making it harder to trust the systems for accountability, transparency, and resources in tourism governance. This condition is closely related to the dominance of the central authority, which holds significant control over the tourism industry and positions it as a national strategic sector. Consequently, the limited policy flexibility and strict restrictions of the tourism management framework leave local authorities and communities with limited maneuvering options. Statistical testing supports significant relationships, both direct and indirect. This study recommends more genuine and balanced integration between national and local authorities to create mutually beneficial opportunities, strengthen sustainability, and enhance international competitiveness through multi-stakeholder engagement in more inclusive governance. This research employs a quantitative, exploratory approach to elucidate the political dynamics and constraints that limit the involvement of local tourism authorities and communities in tourism management in Mandalika, Indonesia. Full article

N₂O emissions exacerbate the greenhouse effect, urgently demanding advances in abatement technologies. Catalytic decomposition of N₂O over cobalt-based oxides with alkali metal promoters remains challenging because these catalysts are used in pelletized form, limiting their activity to a narrow outer-shell region due to internal diffusion limitations. However, research efforts continue to focus on enhancing Co–alkali metal contact on unsupported powder samples under inert conditions, even though, under industrial conditions, catalysts are exposed to inhibitory components of waste gases and N₂O, and the powder form is unsuitable for practical application. This study aims at testing N₂O decomposition over catalysts with a Co₃O₄-Cs active phase supported on a ceramic foam. For this purpose, we characterized these catalysts by H₂ temperature-programmed reduction, H₂O and NO temperature-programmed desorption, atomic absorption spectroscopy, and X-ray diffraction and assessed their catalytic performance under an inert-gas atmosphere and with O₂, water vapor, and NO to simulate industrial conditions. Using a pseudo-homogeneous, one-dimensional model of an ideal plug flow reactor in an isothermal regime, the simulation calculations for a full-scale catalytic reactor for N₂O abatement in waste gas from HNO₃ production were performed. The Cs₂CO₃ precursor significantly enhanced catalyst reducibility and electron transferability, increasing N₂O decomposition efficiency in inert gas, but its high hygroscopicity decreased resistance to water vapor and NO, overriding its advantages under industrial conditions. Conversely, glycerol-assisted impregnation enhanced catalyst performance regardless of Cs precursor. These foam-supported catalysts offered several other advantages, including lower pressure drop and lower active phase loading with matching catalytic activity. Based on our findings, depositing Cs₂CO₃ on ceramic foam through glycerol-assisted impregnation may facilitate catalytic N₂O decomposition at the industrial level and, therefore, promote environmental sustainability by reducing N₂O emissions. Full article

Urban trees provide important benefits but can also pose safety risks when stability is reduced. Visual Tree Assessment (VTA) is typically the first step in risk analysis and is sometimes complemented by instrumental methods such as dynamic and static tests. Static pulling tests provide quantitative information on anchorage, but their cost and logistics limit use to site-specific applications. This study evaluates a low-cost Micro-Electro-Mechanical Systems (MEMS) inclinometer for quasi-static inclination measurements during a static pulling test, combining a laboratory calibration against a geometric reference with field comparisons against a professional high-precision inclinometer commonly used in static pulling tests. In the laboratory, using a calibrated tilting beam and a 120 s averaging window, the MEMS sensor yielded absolute errors on the order of a few hundredths of a degree (up to ≈0.015${}^{\circ }$) compared to the geometric expectation. In the field, comparisons were performed in the relative domain (baseline on the first stable plateau) along the longitudinal component, showing high concordance with the reference high-precision inclinometer commonly used in arboricultural pulling tests (e.g., $r\ge 0.99$, RMSE $\approx 0.04$–$0.{07}^{\circ }$, Deming slope $\approx 1.02$–$1.05$). These results support the feasibility of low-cost MEMS for static tilt assessment. Given battery-powered wireless operation and simple processing, they indicate a potential for wider deployments in repeated or scheduled quasi-static assessments (e.g., during controlled pulling tests), complementing professional instrumentation. Full article

Aminoglycosides remain important components of combination therapy for complicated Klebsiella pneumoniae infections in Vietnam; however, gene-level evidence linking aminoglycoside-modifying enzymes (AMEs) with minimum inhibitory concentrations (MICs) and multidrug resistance is limited, particularly in tertiary-care settings in southern Vietnam. A cross-sectional analysis was conducted on 186 non-duplicate aminoglycoside-resistant Klebsiella pneumoniae clinical isolates collected in a tertiary-care hospital in Ho Chi Minh City. Species identity was reconfirmed using ZKIR qPCR. MICs for amikacin, gentamicin, and tobramycin were determined by broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) guidelines, and 14 AME genes were detected using targeted qPCR. Associations between AME genes, aminoglycoside MICs or susceptibility categories, and co-resistance to major antibiotic classes were assessed using non-parametric and exact tests with Benjamini–Hochberg false discovery rate correction, with emphasis on effect direction and clinically interpretable genotype–phenotype patterns beyond statistical significance alone. AME genes were highly prevalent, with ant(2″)-Ia, aac(6′)-Ir, and aac(6′)-Ib detected in 97.3%, 91.9%, and 89.8% of isolates, respectively. The presence of aac(6′)-Ib and aac(6′)-Ih_v was associated with higher aminoglycoside MICs, resistance to amikacin and tobramycin, and broader multidrug resistance, including carbapenem resistance, whereas several other AMEs were linked to lower MICs. These findings indicate that specific AME profiles, particularly aac(6′)-Ib and aac(6′)-Ih_v, are associated with intensified aminoglycoside resistance in this setting and support the need for gene-informed surveillance to prioritise confirmatory MIC-based Antimicrobial Susceptibility Testing (AST) to guide local antimicrobial stewardship. Full article

Safe navigation in dynamic environments remains challenging because classical distance-based constraints ignore the coupling between a robot’s translational motion and attitude dynamics, and fixed safety margins are either over-conservative or risky under varying uncertainty and approach speed. This paper presents a Risk-Aware Model Predictive Control (RA-MPC) framework that addresses both limitations through two integrated components. First, we introduce Orientation–Motion Coupled Control Barrier Functions (O-MCBFs) that enforce unified safety constraints linking collision avoidance with attitude stability limits, preventing dangerous pose configurations during dynamic obstacle avoidance. Second, we develop Risk-Aware Adaptive Margins (RAAMs) that compute time-varying safety buffers based on relative velocity, robot braking capability, and prediction uncertainty, enabling context-dependent safety–efficiency trade-offs without manual parameter tuning. The proposed method integrates these components into a quadratic programming formulation within MPC, ensuring real-time computational tractability. Experimental results demonstrate higher success rates, smoother trajectories, and improved progress toward the goal, with no observed safety violations under the tested conditions. These findings indicate that coupling pose-space safety with risk-adaptive margins provides a principled and practical path to safe and efficient navigation in dynamic scenes. Full article

This study examines how aggregate financial risk tolerance (FRT), measured from repeated survey responses, co-evolves with stock-market dynamics over time. The observed FRT index is treated as a noisy preference signal containing both gradual drift and episodic deviations, and its market relevance is evaluated under time variation, frequency components, and stress regimes. Using monthly data that align the survey-based FRT index with market returns and risk measures, a three-part econometric design is implemented. First, a time-varying parameter VAR (TVP-VAR) characterizes bidirectional, non-constant linkages between FRT and market outcomes. Second, signal-extraction methods decompose FRT into a smooth “normal” component and a high-frequency “abnormal” component (with robustness to alternative filters) to test whether short-run deviations contain distinct information for volatility and downside risk. Third, a Markov-switching specification assesses state dependence by testing whether the FRT–market relationship differs between low-stress and high-stress regimes. Across specifications, the FRT–market linkage is strongly state dependent: the sign and magnitude of FRT effects drift over time and differ across regimes, with high-frequency FRT deviations aligning more closely with risk dynamics than the smooth component. Predictive validation is provided via out-of-sample forecasting of next-month market risk using elastic net and gradient boosting relative to an AR(1) benchmark; explainability analysis (SHAP) indicates that abnormal FRT contributes incremental predictive content beyond standard market-state variables. Overall, the framework offers a mathematically transparent approach to modeling survey-based preference signals in markets and supports regime-aware forecasting and risk-management applications. Full article

Centrifugal compressors (CCs) are key components of marine power plants (MPPs), supporting engine boosting, boil-off gas (BOG) handling on liquefied natural gas (LNG) carriers, and auxiliary services such as heating, ventilation, and air conditioning (HVAC). However, recent publications are often fragmented by domain (aerodynamics, mechanical design, standards, and digitalization), complicating cross-domain engineering decisions for marine duty cycles. This structured review follows an explicit protocol to synthesize peer-reviewed studies (2015–2025) retrieved from Scopus and Web of Science and organizes the evidence by application class: turbocharger-integrated stages for marine diesel and gas-turbine engines, LNG/BOG compression trains, and auxiliary onboard services. The synthesis consolidates (i) aerodynamic KPIs (pressure ratio, efficiency, surge and stall margins, and operating range), (ii) mechanical and lifecycle enablers (seals, bearings, and rotordynamics), and (iii) quantified impacts of digital methods (control, diagnostics, and digital twins). Reported trends include single-stage pressure ratios of ~5.4–5.7, multistage overall pressure ratios exceeding 10, and surge-margin improvements of ~40–44% associated with advanced diffusers as well as casing and endwall treatments. Industrial case studies (non-marine) report downtime reductions of ~25–35% and maintenance-cost reductions of ~25%, while evaluated diagnostic datasets show high accuracy. Key gaps remain in marine-specific validation datasets and harmonized testing and data standards. Full article

Potato harvesters operating in hilly and mountainous areas are often subjected to harsh working conditions such as high temperature, sun exposure, and high torque excavation. Due to the fluid sealing characteristics, closed loop hydraulic systems are prone to high temperatures during long-term continuous operation, resulting in a decrease in fluid viscosity, poor lubrication, severe wear, and power attenuation. This study investigates the hydraulic system of potato harvesters in hilly terrain, systematically analyzing its energy transfer process and identifying key heat-generating components. Based on an optimization strategy that extends the flow path of high-temperature fluid within the tank, four distinct tank designs were proposed. Computational fluid dynamics (CFD) and thermodynamic simulations were conducted to evaluate their heat dissipation performance, followed by full-machine validation testing. Results indicate that the walking and lifting systems are the primary heat sources. The dual pump contributes the highest proportion of heat (52.07%), followed by the walking motor (20.54%). The heat exchanger dissipates 72.91% of the heat, while the hydraulic oil tank accounts for 14.93%. Among the four tank designs, Tank 0 exhibited the fastest temperature rise, reaching a thermal equilibrium of 83.27 °C, whereas Tank 1 had the lowest equilibrium temperature (78.62 °C). Heat dissipation efficiencies for the tanks were 7.8%, 12.9%, 10.1%, and 11.6%, respectively. The residual gas volume fraction decreases significantly as the bubble diameter increases, due to the higher buoyancy and faster rise velocity of larger bubbles, which leads to shorter residence times and more effective precipitation. Tank 1 achieved the lowest equilibrium temperature, indicating the best thermal efficiency. Tank 3 showed the best overall degassing performance, particularly for medium-to-large bubbles. Tank 1 was selected as the optimal final design because it could offer an excellent balance, with very good cooling and competitive degassing (especially for small bubbles). Field tests confirmed a 14.8% reduction in thermal equilibrium temperature for Tank 1 (75.6 °C) compared to Tank 0 (88.7 °C). Simulation and experimental data showed strong agreement, with maximum errors of 9.2% for return fluid temperature, 12.7% for cooling return fluid temperature, 9.7% for pressure, and 8.5% for flow rate. Average errors remained below 8.4% for pressure and 7.6% for flow rate. These results validate the accuracy of the simulation model and the effectiveness of the tank optimization method. Full article

The seismic vulnerability of existing reinforced concrete buildings is often exacerbated by the inadequate mechanical performance of non-structural components, such as masonry infill walls, which may exhibit brittle behavior and limited deformation capacity under seismic actions. This issue highlights the need for innovative and compatible strengthening materials capable of improving ductility and damage tolerance while maintaining adequate mechanical strength. This study presents an experimental investigation aimed at developing a sustainable fiber-reinforced plaster manufactured exclusively from locally sourced natural materials from the Calabria region, including cork granules, broom fibers, and natural hydraulic lime. Following a preliminary experimental phase, the mixture containing 30% cork granules was selected as the reference matrix due to its favorable mechanical performance and deformability. In the present phase of the research, several composite formulations incorporating broom fibers were produced and experimentally characterized. Uniaxial tensile tests were conducted on broom fibers to assess their reinforcing potential, while compressive and flexural tests were performed on the plaster matrices. The experimental results show that the incorporation of broom fibers significantly enhances flexural behavior and post-cracking ductility, while maintaining compressive strength levels compatible with structural retrofit applications. The study demonstrates that the combined use of cork and broom fiber effectively enhances the mechanical performance of the plaster by promoting ductility, improving flexural behavior, and limiting crack initiation and propagation. The high tensile strength of the fibers promotes effective crack-bridging mechanisms and improved energy dissipation capacity. Overall, the combined use of cork aggregates and broom fibers results in a mechanically balanced plaster composite characterized by enhanced deformability and reduced brittleness. These features make the proposed material particularly suitable for the strengthening of masonry infill walls and for applications where improved ductility and damage tolerance are required, such as seismic retrofitting and restoration of existing buildings. Full article

This study examines the effectiveness of difference-education interventions as institutional strategies that support students’ coping during the transition to college. We tested an intervention with two components: a resource-focused approach that makes the hidden rules of higher education explicit, and a student-driven narrative approach featuring unscripted stories from peers describing how they navigated common academic- and life challenges. The study involved 716 first-year students at a Minority-Serving Institution who were randomly assigned by course section to one of the two intervention conditions, with a campus-wide comparison group (N = 2708) drawn from non-participating sections. Results showed significant improvements in Fall-semester GPA and first-year retention for students in both intervention conditions relative to the no-treatment comparison group. Contrary to prior work, first-generation students did not benefit more than their continuing-generation peers. These findings suggest that difference-education interventions may support coping by helping students make sense of academic challenges, anticipate institutional demands, and respond to setbacks with greater persistence. Resource-based and narrative-based approaches may therefore contribute to students’ ability to manage academic difficulty and remain engaged during the early stages of college, particularly in Minority-Serving Institutions. Full article

In this work we test the possibility of accounting for the positron anomaly with annihilating dark matter particles without contradicting the gamma-ray constraints due to their unconventional space distribution. To achieve that, we consider two-component dark matter, whose major constituent is inert and forms the halo of the Galaxy, while the second, minor, component consists of annihilating particles that could form some different structure. This work is the next logical step after our previous “dark disk model” where an active DM component was considered to form a disk, allowing good suppression of accompanying gamma-radiation. Nowadays that model is not enough to avoid the contradiction, so we are testing a new, more complex one with a spiral spatial distribution like the one of baryons. We have previously tested two simplified toy models of ring-like density profiles and one simple spiral density profile that have shown good improvement compared to the disk case. In this work, we take things further and consider a more physically grounded density profile constructed on the base of a modern model of the baryon density of our Galaxy. Contrary to our expectations, this advanced model shows much worse agreement with the data than previous toy models. Full article

Parylene C films are subjected to inadequate corrosion resistance due to their relatively low adhesion and structural defects. To address this challenge, the CVD Parylene C film (10 μm thick) was composited with Al₂O₃ film (30 nm thick) prepared with atomic layer deposition (ALD) technology in this work. Optical microscopic results indicate uniform thickness of the films and the reduced adhesion of Parylene C based thick films. SEM-EDX and AFM results show that the composite films have more blurred mounds morphology than the individual films, and Al₂O₃ film decreases the surface roughness of Parylene C film; compared with the single-layer film, the R_a value of the bilayer film decreased by approximately 6%. XPS, FTIR and XRD analyses confirm the structural components of Al₂O₃ and Parylene C films and the annealing effect of ALD process on Parylene C film. Tafel polarization and electrochemical impedance spectroscopy tests reveal that the 304-Parylene C–Al₂O₃ system exhibits the optimal corrosion resistance; its corrosion current density (i_corr) is 8.099 × 10⁻⁵ μA/cm² and the ALD Al₂O₃ thin film uniformly coats the Parylene C film, enhancing its physical barrier and chemical passivation under corrosive conditions. Full article