Current Issue : July-September Volume : 2026 Issue Number : 3 Articles : 5 Articles
To address the performance degradation of conventional rare-earth silicate environmental barrier coatings (EBCs) in high-temperature water-oxygen environments, this study developed a novel high-entropy EBC system. The coating with a composition of (Yb1/5Y1/5Lu1/5Er1/5Ho1/5)2Si2O7/Si/SiC was prepared via atmospheric plasma spraying. Thermal cycling corrosion tests were conducted at 1400 ◦C under a 90% H2O–10% O2 atmosphere. Results show that after heat treatment, the monosilicate phase content decreased, and the structure stabilized. The coating surface exhibited a ridge-like morphology with pits and microcracks after corrosion. A porous corrosion layer formed at the edges, and the SiO2 layer thickness increased parabolically from 2.75 μm after 100 cycles to 5.65 μm after 300 cycles. The coating demonstrated excellent corrosion resistance, with degradation initiated by surface thermochemical corrosion, leading to corrosion layer formation and SiO2 accumulation. This study provides important insights for developing long-life EBCs for aero-engine applications....
Hydropower reservoirs contribute to methane (CH4) and carbon dioxide (CO2) emissions, like all aquatic ecosystems. Unique to hydropower reservoirs are degassing emissions that occur when deep-water intakes move water with high CH4 and CO2 concentrations through turbines, leading to the release of these gases. However, few studies from hydropower reservoirs have measured seasonal variability and drivers of degassing fluxes, especially in temperate systems. We measured monthly degassing emissions in temperate Douglas Reservoir (Tennessee, USA) from 2023 to 2024. We found that degassing fluxes were highest in the summertime, and deep-water CH4 and CO2 concentrations were predictable by deep-water dissolved oxygen (DO) concentrations. Degassing emissions accounted for 37–62% of annually estimated CH4 emissions, outweighing ebullitive emissions during summer months. We highlight the value of using DO data to estimate deep-water CH4 and CO2 concentrations and degassing fluxes at higher temporal resolution to improve annualization and extrapolation of reservoir degassing emissions at broader scales....
Historical landfills in coastal environments are at increasing risk of erosion under changing climate conditions. Various studies have highlighted pollutant release associated with potentially toxic elements and flame retardants from such erosional processes, but there has been little focus on per- and poly-fluoroalkyl substance (PFAS) release as a result of physical erosion at such sites, despite landfills being highlighted as a key source of PFAS to the water environment. This study presents a rapid screening approach that could be adopted at scale by regulators to assess the presence and potential flux of PFAS released at three historical municipal waste landfill sites in the UK. The sites selected cover a range of epochs prior to rigorous environmental regulation from the second half of the twentieth century. At the older waste deposits (Withernsea: 1950s–1960s; Hessle: 1930s–1970s), all 52 PFAS analysed in solid materials were below the detection limits except for two samples where modest concentrations (0.92–1.98 ng/g) of perfluorooctane sulfonate (PFOS) and perfluoroethylcyclohexane sulfonate (PFecHS) were detected. At the more recently operational site (Crosby: 1970s–1980s), the legacy PFAS chemicals, PFOS and perfluorooctanoic acid (PFOA), were present in all samples in modest concentrations (6.01–8.22 ng/g for PFOS; 0.62–1.20ng/g for PFOA) below contaminated land thresholds. At this site, it was possible to model the flux of PFAS release based on LiDAR surveys of the eroding waste terrace over an 18-year period. This showed an annualised total solid phase PFAS (PFOS plus PFOA in this case) flux in the region of 2.5–16.9 g/yr, which is towards the lower end of the reported landfill leachate flux at inland sites. While such releases are relatively modest on an individual site basis, in transitional and coastal waters in heavily urbanised and (post-)industrial regions, the aggregated solid phase PFAS flux from the large number of eroding historical landfills (n = 114) could be significant....
To analyze the characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals in specimens with different water contents during impact loading, impact tests were conducted on sandstone under dry, natural, and saturated conditions using the split Hopkinson pressure bar (SHPB) system. The results show that water reduces the dynamic compressive strength and elastic modulus of sandstone, changes the failure mode from tensile failure to tensile-shear failure, and increases the amount of small-sized fragments after failure. AE and EMR signals effectively reflect the entire deformation process of specimens with different water contents under impact loading. In the elastic stage, only EMR signals appear, indicating that EMR is more sensitive to crack generation. In the yield stage, the AE signal count and energy increase sharply, indicating that the response to specimen failure is better. By comparing AE and EMR signals at different stages, it was found that water inhibits both the propagation and energy of AE and EMR signals. The damage factor D, quantified by AE and EMR counts, accurately represents the damage suffered by specimens with different water contents during impact loading. This study significantly advances the understanding of failure mechanisms in specimens with varying water contents and contributes to practical engineering monitoring of water-bearing rock mass stability....
The widespread use of biochar in soil remediation has heightened interest in the role of its derived dissolved organic matter (DOM) in soil nutrient dynamics. However, how pyrolysis temperature shapes the characteristics of DOM released from sludge biochar remains unclear. The study examined variations in the composition and properties of DOM extracted from sludge biochar under two different solutions—ultrapure water (UP) and artificial root exudates (ARE)—across a range of pyrolysis temperatures. Results indicate that the dissolved organic carbon (DOC) content did not differ significantly between extraction environments. In contrast, pyrolysis temperature markedly influenced both the content and composition of DOM. DOM in sludge biochar was primarily composed of humic-like (C1, C2, C3) and tyrosine-like (C4) components. Specifically, DOM from low-temperature biochar was dominated by C2, C3, and C4, whereas high-temperature biochar contained mainly C2 and C4....
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