Search Results (2,279)

The pantograph–catenary system is a crucial component of rail transit vehicles, performing the vital function of electric energy transmission. During train operation, the current-carrying components continuously emit particulate matter into the surrounding environment due to friction, and these particulate emissions have a significant impact on human health. However, research on the correlation between the current-carrying friction of carbon contact strips and particulate matter emission characteristics is rarely reported. Based on a semi-enclosed pin-on-disc current-carrying friction and wear test rig, this paper investigates the effects of varying current intensity under different contact load conditions on the friction and wear performance of carbon/copper pairs, as well as the associated particulate matter emission behavior. It reveals the damage characteristics of carbon contact strips, the particulate matter emission characteristics, and the relationship between them under different service conditions. The results indicate that the wear mechanism and particulate matter emission behavior of carbon contact strips are jointly influenced by current magnitude and contact load. In the absence of current, increasing the load exacerbates the mechanical wear on the carbon friction pair surface, while elevating the emission concentration of particles of various sizes and stabilizing the particle size distribution. Under current-carrying conditions, a higher contact load effectively reduces the frequency of arc discharges between the friction pair. Meanwhile, the degree of arc erosion on the contact surface worsens with increasing current intensity. Arc discharges instantaneously lead to a sharp increase in particulate emissions, and the higher the discharge intensity or the greater the number of discharges, the higher the particulate concentration around the contact pair. Full article

To address the global challenge of desertification, it is essential to develop sustainable and biodegradable materials for sand fixation to support ecological restoration in arid regions. In this work, a CNS/PAM biocomposite system was constructed through the supramolecular assembly of highly flexible two-dimensional cellulose nanosheets (CNS) and polyacrylamide (PAM). Benefiting from the flexible layered structure of CNS and the abundant hydroxyl and carboxyl groups on their surface, a conformal coating and an interparticle bridging network were formed via hydrogen bonding and coordination interactions with mineral cations. The introduction of PAM further regulated the hydrogen-bonding network, which improved structural uniformity and mechanical integrity. The resulting composites showed strong resistance to both wind and water erosion (erosion loss < 0.1%) and reached a compressive strength of up to 0.23 MPa, while maintaining good environmental compatibility. This study clarifies the structure–interaction–property relationships of cellulose nanosheet-based supramolecular assemblies and provides a new theoretical basis and practical pathway for designing biodegradable sand-fixing materials. Full article

The accumulation of polyethylene (PE) in aquatic ecosystems represents a significant environmental challenge due to the polymer’s high molecular weight and chemical stability. This study investigates the biodegradation potential of Hafnia paralvei UUNT_MP29, a bacterial strain isolated from the gut of common carp (Cyprinus carpio), for low-density polyethylene (LDPE). Initial screening on LDPE-emulsified agar confirmed extracellular enzymatic activity through the formation of distinct clear zones. Quantitative analysis showed a cumulative mass loss of 24.10% by Day 16, with the most intensive degradation occurring between Days 4 and 8, which closely correlated with maximum bacterial count (CFU/mL). Kinetic modeling indicated that the degradation followed a first-order rate law (R² = 0.9269), with a rate constant (k) of 0.2991 days⁻¹ and a remarkably short half-life (t_1/2) of 2.32 days. Structural characterization via FTIR spectroscopy demonstrated oxidative transformation, evidenced by a reduction in sp³ C-H stretching and the emergence of C-O/C-O-C functional groups. SEM micrographs further confirmed extensive bio-deterioration, including surface pitting and macroscale erosion. Thermal analysis (TGA/DTG) supported these findings, showing a significant 10.95 °C decrease in the maximum degradation temperature (T_max), indicating a reduction in polymer chain length. These results suggest that H. paralvei UUNT_MP29 is a highly efficient agent for the rapid breakdown of polyethylene and highlight the potential of aquatic gut microbiota as reservoirs for plastic-degrading biotechnologies. Full article

The conservation and restoration of architectural heritage face dual challenges from natural erosion and human interference, necessitating the adoption of efficient and non-contact digital technologies to achieve sustainable preservation. Virtual reality (VR) technology, with its advantages of immersion, interactivity, and visualization, provides a novel technological pathway for digital documentation, conservation decision-making, and public presentation of architectural heritage. Taking the Fuliang Red Pagoda in Jingdezhen, Jiangxi Province, as the research object, this study constructs a high-precision digital reconstruction and VR interactive application workflow based on the integration of terrestrial laser scanning and close-range photogrammetry. Through point cloud denoising, Iterative Closest Point (ICP) registration, and Poisson surface reconstruction algorithms, a refined three-dimensional model of the pagoda is achieved, and an immersive VR system is developed with functions including component information query, virtual restoration scheme switching, and interactive exploration. The results demonstrate that this technical workflow not only enables non-contact digital archiving of the Fuliang Red Pagoda but also provides a visual decision-support tool for conservation interventions. Under full-scene operation, the system achieves an average rendering frame rate of 92 FPS and maintains motion-to-photon latency below 20 ms, ensuring good real-time performance and interaction stability. The findings indicate that VR-based digital technologies can enhance the scientific rigor of conservation planning and promote public engagement while adhering to the principles of authenticity and minimum intervention. This study provides a replicable technical pathway and practical reference for high-precision digital reconstruction and sustainable conservation of historic buildings. Full article

The development of fusion technology requires materials that can withstand heat, erosion, and activation at the edge of fusion plasma. Thanks to its high melting point, superior thermal conductivity, and excellent resistance to sputtering and retention, tungsten (W) has been regarded as the leading candidate for the plasma-facing materials (PFMs) of the main chambers and divertors in controlled thermonuclear fusion reactors. Nevertheless, W-PFMs are prone to complex severe surface deterioration under extreme service conditions during operation in fusion reactors. This includes physical/chemical sputtering, which results in material loss and plasma contamination; He-induced blistering and fuzz formation, which reduce thermal conductivity by several orders of magnitude; thermal fatigue cracking caused by transient loads; and neutron irradiation embrittlement, which leads to hardening, swelling, and loss of ductility. To overcome these issues while maintaining core thermophysical properties, protective surface layers have been fabricated primarily via chemical vapor deposition (CVD), physical vapor deposition (PVD), and spray and plasma-based surface modification technologies. This review assesses the recent progress in the fabrication of protective surface layers on W for PFM application in fusion reactors from a technical perspective, thereby offering new insights that advance the feasibility of fusion reactors and accelerating the practical realization of sustainable fusion energy systems. Full article

To simulate the erosion damage behavior of thermal barrier coatings (TBCs) under actual service conditions in an aircraft engine environment, this study developed a multi-factor coupled test setup capable of simulating combined loading under high-temperature (1150 °C), high-speed (0.4 Mach), and solid-particle erosion conditions. Yttria-stabilized zirconia (YSZ) TBCs were prepared using electron beam physical vapor deposition (EB-PVD). For different erosion durations (2 h, 5 h, 8 h, 12 h), the evolution of macroscopic and microscopic morphologies as well as the development of residual stresses in the thermally grown oxide (TGO) layer were systematically investigated. The results indicate that the erosion process of the YSZ coating can be divided into three stages. During the initial high-erosion-rate stage (8.17 g/kg), erosion damage was confined to the grain tips of the columnar crystals, primarily caused by brittle fracture at the grain tips, and the TGO stress was relatively low (−0.6 GPa). During the intermediate stage, the erosion rate was lower (2.74 g/kg). Impact stresses induced microcracks within the columnar grains, which gradually connected to form intergranular fractures. This led to the expansion of localized spalling pits. The interface began to wrinkle, and the stress rose to −2.2 GPa. In the final accelerated failure stage (5.88 g/kg), horizontal cracks fully propagated, leading to large-scale peeling of the coating. The stress was released to −0.9 GPa. The coating failure mechanism evolves from surface damage to interfacial peeling, which is closely related to the coating structure, stress evolution, and interfacial state. Full article

Land degradation caused by soil erosion is a major challenge in Mediterranean sloping agroecosystems, where extreme weather events and conventional land management practices accelerate soil loss and threaten long-term sustainability. This study evaluates and compares three complementary approaches to estimate soil erosion in an olive orchard in Messenia, Greece. Field-based runoff plots provided direct measurements of sediment yield, drone-based Light Detection and Ranging (LiDAR) surveys enabled soil surface change detection through the Difference of Digital Elevation Models (DoD) method, and the Revised Universal Soil Loss Equation (RUSLE) was applied to model erosion risk using site-specific parameters. Results indicate that field measurements and RUSLE estimates are broadly consistent, particularly when the model is calibrated with empirical data, offering reliable insights into soil loss dynamics. In contrast, the LiDAR-DoD analysis identified patterns of soil surface displacement, which reflected spatial variation in surface change across the olive orchard. Overall, the integration of field monitoring, remote sensing, and modeling highlights the strengths and limitations of each method and demonstrates the value of multi-method approaches for improving erosion assessment and supporting sustainable land management in vulnerable Mediterranean landscapes. Full article

Modern turbine engines, when operating at high temperatures, can inhale calcium–magnesium–alumina–silicate particles (CaO-MgO-Al₂O₃-SiO₂, CMAS) from the air, which can erode the thermal barrier coatings on the blade surface, affecting the service life of the thermal barrier coatings and, in severe cases, leading to premature blade failure. Therefore, it is of great significance to effectively detect the thickness of CMAS deposited on the surface of the thermal barrier coatings at an early stage of CMAS erosion to ensure the high-temperature structural integrity of the hot-end components of aeroengines. Based on this, this study proposes a method combining terahertz time-domain spectroscopy technology and a hybrid machine learning algorithm for the quantitative detection of the thickness of CMAS on the surface of thermal barrier coatings. Firstly, the terahertz time-domain spectroscopy experimental data of CMAS were obtained using a terahertz experimental system, and the refractive index and absorption coefficient of CMAS in the terahertz frequency band were calculated. The FDTD method, Gaussian noise addition, and wavelet denoising processing were combined to further simulate the terahertz detection process of thermal barrier coatings with different thicknesses of CMAS attached to the surface under high-temperature conditions, and the terahertz simulation detection data were obtained. Principal component analysis (PCA) was used to reduce the dimensionality of the original experimental and simulation data, and a support vector machine (SVM) model integrating PCA and bacterial foraging optimization (BFO) algorithm was constructed. The research results show that the integrated model exhibits excellent performance in predicting the thickness of CMAS, with a correlation coefficient of 0.95, and the mean absolute error (MAE) and root mean square error (RMSE) are 0.13 μm and 0.46 μm, respectively. This study provides a new high-precision method for non-destructive detection of the thickness of CMAS on the surface of thermal barrier coatings, which has certain engineering application value for ensuring the service performance of thermal barrier coatings under harsh service conditions. Although the current method is based on simulated and experimental data under controlled conditions, it has the potential to be developed into an in situ monitoring strategy in the future, enabling real-time assessment of CMAS thickness on the coating surface during engine operation. Full article

The structural integrity of hydraulic structures is frequently weakened by local scour processes downstream of weirs. This study investigates the relationship between hydraulic parameters and erosion patterns to improve the predictability of bed deformation. The research methodology integrates detailed field measurements from the Radomka River in Piaseczno with laboratory experiments using a 1:30 physical scale model of the existing weir. Bed shear stress demonstrated the strongest correlation with maximum scour depth (r ≈ 0.93; RMSE ≈ 0.0032), as it directly represents the tangential force acting on sediment particles at the bed surface, which controls their entrainment, transport capacity, and ultimately the intensity of local scour development, whereas near-bed velocity showed weak and non-significant dependence (r ≈ 0.26; ${\rho }_s$ ≈ −0.11). This weak dependence reflects the dominance of turbulence-induced velocity fluctuations and localized vortical structures in the near-bed region, which obscure the relationship between mean velocity and sediment mobilization. The relationships between mean velocity, Froude number, and scour depth were moderate (r ≈ 0.63–0.73) and showed nonlinear characteristics, confirmed by HSIC values up to 9.1 × 10⁻³, due to the complex interaction between flow structures and evolving bed morphology. This nonlinearity results from the interaction between turbulent flow structures, jet-induced vortices, and the dynamically evolving bed morphology, combined with the threshold-controlled and nonlinear response of sediment transport to hydraulic forcing. Among all tested parameters, bed shear stress ranked as the dominant predictor of scour depth, outperforming velocity-based indicators. These findings imply that including bed shear stress parameters significantly improves hydraulic structure safety assessments. This study based on 11 experimental runs concludes that a combined field and laboratory approach provides a robust framework for river engineering. Finally, an improved understanding of erosion mechanisms, as presented in this work, enhances the prediction of local scour development and supports the design of more resilient hydraulic infrastructure. Full article

Objective: To evaluate the ability of an experimental propolis/chitosan varnish to inhibit the erosive process in primary tooth enamel. Materials and Methods: Forty-two primary incisors were selected and divided into three groups (n = 14): control/no treatment, Duraphat^® varnish, and propolis/chitosan varnish. The varnishes were applied to the experimental area and left in place for 4 h. After varnish removal, the specimens were subjected to erosive challenges with Coca-Cola^®. The quantitative outcome variables were mineral loss assessed by longitudinal microhardness, surface roughness, and wear profile. The data were analyzed using ANOVA and Tukey’s test (p < 0.05). Results: Wear profile and surface roughness analyses showed no significant differences among the groups (p > 0.05). In the microhardness analysis, the control and experimental groups showed significant differences between the control and demineralized areas and between the control and experimental areas (p < 0.05). In the Duraphat group, a significant difference was observed between the control and experimental areas (p < 0.05). Conclusion: The experimental propolis/chitosan varnish was unable to prevent the progression of mineral loss in the enamel of primary teeth subjected to erosive challenge. Duraphat^® fluoride varnish was also unable to protect the enamel. Clinical relevance: Several studies have investigated the use of propolis and chitosan in dentistry, and promising results have been reported when these agents are used individually; however, the propolis/chitosan combination remains poorly explored. To the best of our knowledge, this is the first study to investigate this combination for dental erosion in primary teeth. Full article

Petrochemical-based plastics are widely used due to their convenience and low cost, with polyethylene (PE) being the most produced globally. However, the lack of efficient and sustainable treatment methods for conventional plastic wastes has led to severe environmental pollution. A new fungus strain capable of degrading PE was isolated from soil samples collected at a waste disposal site in Henan province and identified as Aspergillus sydowii W144. After 30 days of incubation under solid-state culture conditions, the strain demonstrated significant oxidative depolymerization of low-density polyethylene (LDPE). FTIR results revealed a substantial increase in the carbonyl index of the LDPE film, while differential scanning calorimetry (DSC) analysis detected an enhanced crystallinity in the LDPE film. Notably, distinct pitting and erosion marks were observed on the surface of LDPE film using scanning electron microscopy (SEM). Quantitative analysis showed a weight loss rate of 6.39% and a reduction in Weight-Average Molecular Weight (Mw) by 50.93%. Among currently identified PE-degrading strains polyethylene, A. sydowii W144 exhibits particularly outstanding depolymerization efficiency, especially on untreated PE. Based on the whole-genome data of A. sydowii W144, a preliminary model of the putative polyethylene degradation pathway in A. sydowii W144 was constructed through homology-based sequence analysis and by referencing previously reported polyethylene degradation pathways. Laccase/multicopper oxidase plays a key role in the initial oxidation of PE. Heterologous expression of the candidate gene laccase4 in Pichia pastoris yielded an active enzyme (~56 kDa) with a laccase activity of 460 U/L, confirming its functionality. This study provides a novel microbial resource and potential enzymatic tools for PE biodegradation. The strain exhibits a promising application in complex ecosystems for PE pollution. IMPORTANCE: The polyethylene-degrading strain A. sydowii W144 isolated in this study exhibits highly efficient depolymerization capabilities, particularly under solid-state culture conditions. Genomic sequencing analysis enabled the construction of a potential polyethylene (PE) degradation pathway and facilitated the identification of key laccase and multicopper oxidase genes involved in this process. The isolation of this novel strain enriches the microbial resources available for PE waste treatment and offers new insights into the mechanisms of plastic biodegradation. Full article

Ageing radically alters the physicochemical properties of microplastics, significantly increasing their affinity for environmental pollutants. However, the slow nature of natural degradation necessitates the development of efficient laboratory protocols. This study establishes an accelerated ageing methodology that reflects natural dynamics by comparing Polyethene terephthalate microplastics (PET MPs) exposed to sunlight (3 months) with those exposed to laboratory UV-C radiation (varying lamp numbers and 24–336 h). scanning electron microscopy (SEM) imaging confirmed progressive surface degradation, including increased roughness, micro-cavities, and erosion. Photo-oxidation was evidenced by an increase in the carbonyl index (CI) from 7.43 ± 0.30 to 8.97 ± 0.35 (UV-aged) and 11.45 ± 0.45 (sun-aged). Furthermore, crystallinity significantly decreased from 59.5% to 54.4% and 16.6%, respectively, while the point of zero charge (pH_PZC) shifted from near neutral (6.5–7.0) to below 2.0. Notably, high-intensity, short-term UV-C exposure accelerated surface functionalization, enhancing cadmium adsorption capacity (q_e = 1.9 mg/g). The laboratory protocol provides rapid reactivation on the surface, serving as a proxy for prolonged sunlight exposure. Consequently, these findings offer a framework for assessing heavy metal uptake and the broader environmental implications of microplastics in aquatic environments. This understanding supports pollutant evaluation and sustainable water management for aquatic ecosystem protection. Full article

Rainfall-induced erosion poses a serious threat to river levee slopes, where raindrop impact and surface runoff trigger particle detachment, rill initiation, and gully development, leading to rapid soil loss and local instability. This study experimentally evaluated short-fiber reinforcement as an erosion-control measure for levee slopes under controlled rainfall conditions. Laboratory embankment models were constructed using a uniform soil mixture and compacted under consistent moisture conditions. Simulated rainfall was applied at intensities of 50 and 100 mm/h. Erosion progression was monitored through time-series observations and quantified using sediment collection and three-dimensional surface measurements. Comparative tests were performed on unreinforced and fiber-reinforced slopes to examine the influence of fiber bridging and surface anchoring on the initiation and development of erosion. The results showed that short-fiber reinforcement delayed rill formation and reduced soil loss. Under 50 mm/h rainfall, 1% coir fiber reduced the eroded mass by approximately 70%, whereas polypropylene fiber achieved approximately 42% reduction compared with the unreinforced control. These findings suggest that short natural fibers can effectively enhance the erosion resistance of compacted levee slopes under rain. Full article

Protrusions on the flow-passing surfaces of hydraulic machinery readily induce localized cavitation and exacerbate cavitation erosion damage. This study investigates the influence of a spherical cap protrusion on a flat wall on the collapse dynamics of cavitation bubbles. By integrating high-speed photography experiments with Kelvin impulse theory, an impulse model is constructed based on boundary treatment and potential flow superposition. The dynamic evolution characteristics of cavitation bubbles at both symmetric and asymmetric positions are systematically analyzed, with emphasis on the effects of the spherical cap angle and bubble azimuthal angle on bubble morphology evolution, bubble wall collapse velocity, and the magnitude and direction of the Kelvin impulse. The results indicate that as the spherical cap angle increases, the non-spherical collapse of bubbles at symmetric positions becomes substantially more pronounced, and the collapse mode transitions from flat wall-dominated to protrusion-dominated behavior. At asymmetric positions, a larger spherical cap angle intensifies the non-uniformity of the bubble wall collapse velocity: the minimum velocity continues to decrease, and the location of this extremum shifts toward the side adjacent to the protrusion. Meanwhile, the Kelvin impulse magnitude exhibits accelerating growth, and its direction reorients from perpendicular to the wall toward the protrusion structure. Full article

The adhesion between asphalt and aggregate significantly influences the durability and lifespan of road structures. This study employs molecular dynamics simulations to investigate the interface behavior between asphalt and aggregates with varying defect sizes under chloride salt solution immersion and ion infiltration (physical erosion without chemical reactions). The interfacial adhesion energy (E_int), relative ion concentration (R_C), mean square displacement (MSD), and hydrogen bond count were analyzed to assess the adhesion performance of asphalt at the defective aggregate interface. The effects of chloride concentration and temperature on adhesion were also examined. Results indicate that aggregate surface defects enhance local asphalt adhesion within the defect region, although larger defects reduce the global interfacial adhesion energy normalized by total area: the adhesion energy decreases from −417 kcal/mol (defect-free) to −315 kcal/mol (20 Å) and −277 kcal/mol (30 Å), with a reduction of 24–34%. Additionally, defects accelerate ion diffusion significantly, with diffusion coefficients of water and ions increasing by up to 69%, promoting chloride ion accumulation, which exacerbates erosion physical interface deterioration. Both elevated temperature and chloride concentration further accelerate this degradation physical interface weakening, with high temperatures causing severe interface damage: adhesion energy decreases by about 28% as temperature rises from 290 K to 340 K, and by 15% as NaCl concentration increases from 0% to 20%. These findings offer a theoretical foundation for understanding the adhesion mechanisms of the asphalt–aggregate interface under chloride erosion chloride ion infiltration and physical erosion and provide insights into enhancing chloride resistance to chloride ion infiltration of road materials. Full article