Search Results (1,373)

The fracture behavior of Beishan granite is a critical scientific basis for evaluating and ensuring the long-term safety of geological repositories for high-level radioactive waste under extreme thermal–mechanical conditions. With increasing emphasis on climate-resilient infrastructure, understanding the mechanical response of deep geological materials under cyclic loading and simulating long-term environmental conditions are essential for sustainable engineering management. Previous studies have predominantly concentrated on the fracture characteristics under static loading tests, with limited research conducted on the characteristic parameters of acoustic emission (AE) during cyclic loading and the morphology of fractures post-failure. Contributing to the field of resilient infrastructure, this paper presents static and cyclic loading tests using MTS815 equipment on Beishan deep granite (CCNBD type). To determine the rock fracture toughness of mode I and fracture roughness, static loading and cyclic loading tests were conducted using MTS815 equipment with Beishan deep granite (CCNBD type) as the subject of study. AE and 3D laser scanning were employed to acquire the characteristic parameters of acoustic emission (AE) during loading and the morphology of fracture surfaces after failure in the specimens. The results revealed that CCNBD specimens demonstrated pronounced brittle tensile failure under static and cyclic loading conditions. The rock fracture toughness obtained in static tests was 1.180 MPa·m^1/2, whereas under cyclic loading, it was 1.153 MPa·m^1/2. In comparison to static loading, cyclic loading led to a greater accumulation of microcracks inside the specimens, resulting in a 9.8% increase in the length of the fracture process zone. A 57.5% increase in section roughness (fractal dimension) was observed after the failure of the specimen in comparison to static loading. Full article

China’s stringent clean air policies have substantially reduced nitrogen oxides (NO_x) emissions, leading to a general decline in nitrogen dioxide (NO₂). However, surface ozone (O₃) pollution remains severe, creating a complex challenge due to the non-linear relationship between O₃ and its precursors. To disentangle the drivers behind these trends, this study quantifies the impacts of interannual variations in top-down constrained NO_x emissions on surface NO₂ and O₃ concentrations from 2014 to 2021 across mainland China and five national urban agglomerations. We employed the WRF-CMAQ model with a fixed-emission simulation approach, using an observationally optimized NO_x emission inventory derived from the assimilation of surface NO₂ measurements. Results reveal that NO₂ reductions were predominantly emission-driven (>80% post-2017), with declines most pronounced in winter. A strong linear consistency was found between interannual changes in top-down NO_x emissions and attributed NO₂ concentration variations, validating the methodology. In contrast, O₃ responses to NO_x reductions were spatially and seasonally heterogeneous, reflecting a non-linear photochemical regime. In major urban agglomerations (e.g., Beijing–Tianjin–Hebei (BTH), Yangtze River Delta (YRD), Pearl River Delta (PRD)), NO_x reductions post-2018 showed limited effectiveness in mitigating summertime O₃ and even increased O₃ in spring and autumn, indicating a prevalent VOC-sensitive regime where NO_x reduction can disinhibit O₃ formation. Conversely, certain provinces (e.g., Anhui, Shanxi, Jilin) exhibited O₃ decreases, suggesting a NO_x-sensitive regime. The area benefiting from NO_x reductions expanded steadily in summer after 2017 but not in other seasons. This study confirms the efficacy of NO_x-focused policies for reducing primary NO₂ pollution but highlights that mitigating persistent O₃ requires a strategic shift to synergistic, region-specific control of volatile organic compounds alongside NO_x, informed by local chemical sensitivity. Full article

In permanently submerged coastal wetlands, interactions between biogeochemical processes and microbial communities strongly influence greenhouse gas (GHG) fluxes. To improve our understanding of how redox-driven processes shape GHG dynamics in these ecosystems, we investigated the relationships among iron (Fe) pools, microbial dynamics, and the potential GHG production in subaqueous soils from an interdunal wetland in San Vitale Park (Italy), permanently submerged and affected by seasonal oscillations of the saline water table. Two subaqueous soil columns (WAS-2 and WAS-4), collected from similar settings, were analyzed. Surface layers of WAS-4 showed higher salinity and carbonate content, whereas WAS-2 was characterized by overall higher Fe concentrations. Distinct vertical distributions of organic matter and sulfur (S) were shown along depth. Laboratory incubations revealed that nitrous oxide (N₂O) production was up to ten times higher in WAS-2 than in WAS-4, with peaks in the top 13–14 cm, consistent with more active nitrification-denitrification in surface layers. Methane (CH₄) and carbon dioxide (CO₂) fluxes decreased with depth, reflecting reduced availability of labile carbon. Methanomicrobiales dominated CH₄-producing layers, indicating hydrogenotrophic methanogenesis, while amoA-carrying Nitrosomonadales and Thaumarchaeota, occurred in shallow, organic-rich layers where ammonia supported nitrification and denitrification. Denitrifiers mainly belonged to α- and β-Proteobacteria, consistent with their direct contribution to N₂O peaks. Spearman’s correlations showed N₂O positively correlated to sulfur and labile carbon (C), supporting denitrification under moderately reducing conditions. CH₄ and CO₂ positively correlated with organic C (Corg), total nitrogen (TN), and reactive Fe forms, reflecting redox-mediated microbial respiration and methanogenesis. Trace elements (B, Cr, Cu, Ni) acted as micronutrients or inhibitors depending on concentration. Canonical correspondence analysis indicated depth-structured links among gas fluxes, soil chemistry (Corg, TN, S/C, CaCO₃, P), and microbial distributions: surface layers, rich in labile C and nutrients, supported active bacteria and archaea involved in decomposition, nitrification, and denitrification, whereas deeper layers hosted oligotrophic archaea adapted to inorganic substrates. Overall, Fe pools appeared to be associated with soil processes relevant to GHG dynamics, although the extent of their regulatory role remains uncertain due to potential alterations of redox-sensitive Fe fractions during sample handling. These results contribute to broader efforts to predict GHG emissions in submerged wetland soils by linking redox stratification, inorganic chemistry, and microbial functional groups. Full article

Because dust-emission processes driven by local, small-scale winds (e.g., terrain-induced winds) are difficult to accurately capture with mesoscale or larger-scale predictive models, this study employed a CFD-Lagrangian particle-tracking approach to numerically simulate near-surface dust release and transport under different atmospheric stability conditions in the same local flow field. The novelty of this work was the integration of MOST-based stable/neutral/unstable inflow construction with Lagrangian particle tracking, enabling a consistent comparison of stability effects within one framework. This framework is useful for assessing local blowing-sand impacts on short-range receptors. A near-surface source term was specified for PM10-class mineral dust, and particles were emitted using a vertically exponential allocation. Simulations were conducted over a kilometer-scale flow domain containing an idealized cosine hill, and the low-level concentration patterns and dispersion-height variations in the resulting dust cloud were analyzed. Compared with neutral conditions, stable stratification produced higher near-surface concentrations and a lower dispersion height, whereas unstable stratification yielded lower near-surface concentrations and a higher dispersion height; as the $\left|L\right|$ increased, the unstable cases gradually approached the neutral state. The influence of reference wind speed exhibited clear stability dependence: under stable conditions, stronger winds intensified the buoyancy-related suppression of dust dispersion, while under unstable conditions, stronger winds inhibited the vertical spreading of the dust cloud. In addition, reduced air density representative of plateau environments resulted in lower dust-cloud concentrations and higher dispersion heights. These findings highlight the coupled effects of stratification and wind speed on near-field dust dispersion and provide a reference for assessing local dust emissions over complex terrain. Full article

This study evaluates the impact of four drying methods—open sun drying, solar drying, infrared drying, and microwave drying—on the quality attributes and elemental retention of apricots (Prunus armeniaca L.). Experimental trials were conducted in June 2024 at the Tashkent Institute of Chemical-Technology using equal quantities of fresh apricots. Drying was continued until the moisture content, measured gravimetrically, dropped below 20% (wet basis), followed by spectroscopic analysis to determine macro- and microelement concentrations. Solar-dried apricots showed higher retention of essential nutrients in this experimental trial: potassium (2.37%), silicon (0.538%), magnesium (0.145%), calcium (0.176%), and sulfur (0.152%). In contrast, open sun drying led to significant nutrient degradation and poor visual quality. Microwave drying preserved some micronutrients but resulted in surface scorching due to uneven heating. Infrared drying yielded acceptable results but required substantial energy input. Among all methods, solar drying provided the optimal balance of high product quality and energy efficiency. The drying process required negligible electrical energy owing to exclusive reliance on solar radiation. This method supports sustainable food processing by reducing energy demand and greenhouse gas emissions while preserving nutritional quality. The results highlight solar drying as a promising, eco-friendly technique for preserving the nutritional integrity of agricultural products. These findings offer valuable scientific guidance for selecting appropriate drying technologies in the food processing industry, especially in regions with high solar potential. However, the study is limited to a single fruit variety and seasonal conditions. Full article

The Urban Heat Island (UHI) effect represents a major barrier to sustainable urban development, amplifying energy demand, public health risks, and climate vulnerability. This study provides an advanced geospatial assessment of UHI dynamics in Southampton, UK, using Landsat 8 and 9 imagery (2017–2023) to evaluate seasonal and interannual variations relevant to climate-resilient urban planning. This study integrates spatial techniques, including Land Surface Temperature estimation, NDVI-based emissivity modelling, hotspot analysis, and urban–rural gradient profiling, to identify persistent UHI hotspots concentrated in high-density commercial and industrial zones, with intensities reaching 2–3 °C above the citywide mean. It combines seasonal UHI mapping, hotspot analysis, and urban–rural gradient profiling to provide a comprehensive assessment of Southampton’s thermal landscape. The findings reveal persistent UHI hotspots in the city centre and industrial zones, with intensity peaks of 2–3 °C above the mean. Temporal analysis reveals winter-intensified UHI patterns, consistent with climate-sensitive processes observed in temperate coastal environments. Green spaces demonstrate measurable cooling benefits (up to ~1 °C), underscoring their role as sustainable nature-based mitigation strategies. By delivering a replicable, data-driven framework for continuous environmental monitoring, the research directly supports sustainable urban design, targeted greening interventions, and climate-adaptation policies. The findings provide practical tools for reducing heat stress, enhancing energy efficiency, and strengthening long-term urban resilience in medium-sized coastal cities. Full article

Insulation deterioration is the leading cause of premature failures in high-voltage (HV) power equipment, with partial discharge (PD) serving as a key indicator of insulation health. This study introduces a novel compact PD sensor assembly that integrates fiber Bragg grating (FBG) with an exponential acoustic horn to enhance the sensitivity of PD detection. The horn’s geometry effectively collects ultrasonic emissions from the PD, concentrating the acoustic energy to amplify the force on the FBG located at its focal point. To further enhance signal transduction, the FBG is mounted on a fixed solid structure engineered to resonate at higher ultrasonic frequencies that closely align with the dominant acoustic components generated by PD activity, ensuring improved strain amplification and optimal sensitivity. This results in measurable wavelength shifts, which are used for PD detection. A fiber Bragg grating analyzer interrogates the reflected spectra, providing real-time PD detection during HV operations. The effectiveness of the system was validated against the IEC 60270 standard method using laboratory models that emulated corona and surface discharge. The laboratory experiments demonstrated a significant sensitivity of 2.2 pm/Pa and a favorable signal-to-noise ratio of ~21 dB for the proposed sensor module. The dielectric construction of the sensor module, lightweight design, and resistance to electromagnetic interference make it suitable for harsh HV environments and the long-term condition monitoring of HV power equipment. Full article

The Lijiang River is a typical karst landscape river and an important drinking water source for Guilin City. To evaluate its contamination of metals and metalloids, water, surface sediment and four sediment profiles were systematically collected from the Guilin urban segment in April 2023, and the distribution, mobility and potential sources of nine elements (Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb) were analyzed. Results show that metal and metalloid concentrations in the river water are low and water quality is good, whereas sediment concentrations of Cd, Zn, As and Pb are markedly higher than the background values. Compared with other elements, Ni, Cu, As and Cd are more readily mobilized in the aqueous phase and exhibit higher bioavailability. Vertical variation coefficients of all elements in the sediment profiles are mostly below 15%, indicating a relatively stable depositional environment. Correlation analysis and positive matrix factorization identify four main sources: industrial discharge (12.5%), mixed agricultural–geogenic origin (34.3%), traffic emissions (11.9%) and geological background (41.3%). Overall, metal and metalloid contamination in the urban Lijiang River is controllable, but accumulation of Cd and other elements in sediments requires continued attention. Full article

In the current investigation, the solar photocatalytic degradation of two cationic model dyes (methyl green (MG) and crystal violet (CV)) was studied using α-Fe₂O₃/ZnFe₂O₄ nanocomposite. The fine powder of nanoparticles was obtained by co-precipitation method at pH = 10 and characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and UV-vis spectroscopy. The surface properties were further examined through temperature-programmed desorption (TPD) and point of zero charge (PZC) measurements to assess the acid–base characteristics and surface charge behavior of the material. Adsorption and photocatalytic performance were systematically evaluated in both single and binary systems. Dark adsorption experiments showed a better affinity of the α-Fe₂O₃/ZnFe₂O₄ heterosystem towards MG dye in both cases. Under natural sunlight irradiation in the individual system, the photocatalytic activity of the nanoparticles was significantly higher for MG (81.67% removal) compared to CV (41.70%). Kinetics analysis revealed that the photodegradation of both dyes followed a pseudo-first-order model. In binary systems, competitive adsorption effects strongly influenced the degradation behavior, with MG showing preferential adsorption and higher degradation rates. Moreover, the MG discoloration kinetics followed a second-order model, while CV kinetics transitioned from second- to zero-order with increased initial concentration. Full article

Industrial coastal basins that host heavy industry can concentrate metal-bearing dust in school environments. We performed a screening multi-matrix assessment across six schools in Quintero–Puchuncaví (central Chile). We measured As, Cd, Cr, Cu, Ni, Pb, and Mn in surface soils (winter 2023; E1–E4 only), indoor settled dust, and settleable particulate matter (SPM) collected in winter (July 2023) and summer (November 2023). Concentrations were determined by ICP-OES/ICP-MS and interpreted with enrichment factors and the geoaccumulation index. A U.S. EPA screening framework was used to estimate non-carcinogenic hazard (HQ) and incremental lifetime cancer risk (ILCR) for ingestion, inhalation, and dermal contact, as well as cumulative indices for non-carcinogenic (HI) and carcinogenic risk (Risk). SPM carried the strongest anthropogenic signal (EF up to 9900 for Cd, 408 for Cu, and 143 for Pb) and the highest summer loads (Cu > 5000 mg kg⁻¹; Ni > 1000 mg kg⁻¹). Cu dominated non-carcinogenic hazard (HQ up to 137), whereas ILCR was driven by Ni, As, and Cr, exceeding 10⁻⁴ and reaching 10⁻³ at inland/valley schools in summer. Indoor dust showed intermediate burdens, indicating indoor accumulation of outdoor-derived metals, while the winter soil survey provides a baseline indication of outdoor metal reservoirs at the sampled schools. Despite the limited sample size, the results provide screening-level evidence to inform emission control and dust mitigation in school microenvironments. Full article

Titanium dioxide (TiO₂) nanotube arrays (NTAs) were constructed on Ti foil to immobilize Cu₂ZnSnS₄-TiO₂ (CZTS-T/NTAs) via the sol–gel dip-coating technique. The films were characterized by X-ray diffraction (XRD) patterns, field-emission scanning electron microscope–energy dispersive spectroscopy (FESEM-EDX), ultraviolet–visible diffuse reflectance spectra (UV–Vis/DRS), and electrochemical impedance spectroscopy (EIS) techniques. The photocatalytic property of CZTS-T/NTAs was evaluated by the photodegradation of Basic Blue 41 under visible light irradiation. We show that CZTS-T/NTAs have an energy band gap of 2.23 eV, which leads to excellent potential trapping or facilitates the transition of charge carriers under visible light. The parameters R₀ and C₀ of the experimental EIS data, by fitting the proposed electrical circuit, were also discussed. Decreasing R₀ led to an increase in cell capacitance, which resulted in increased carrier generation at the interface between the catalyst and solution and thus an increased photodegradation yield. The response surface methodology (RSM) and central composite rotatable design (CCRD) were used to optimize the effects of the experimental parameters in the degradation process by four key variables (pH, dye concentration, irradiation time, and hydrogen peroxide (H₂O₂) concentration). As a result, the optimized conditions attained a considerable degradation of 95.25%. We also proposed the possible photodegradation mechanism of the photocatalyst. Notably, the proposed catalyst after six consecutive reuse runs retained activity. Full article

The interaction between plasmonic nanoparticles and organic dye molecules plays an important role in varied photonic and optoelectronic applications. In this work, we systematically investigate the optical properties of a water-soluble perylenediimide derivative, N,N′-di(2-(trimethylammonium iodide) ethylene) perylenediimide (TAIPDI), in the presence of different concentrations of silver nanoparticles (AgNPs) under femtosecond (fs) laser excitation. The AgNPs were synthesized via the laser ablation technique. The influence of AgNP concentration on the linear, fluorescence, and nonlinear optical properties of the TAIPDI dye was explored through UV–visible absorption spectroscopy, fluorescence emission measurements, and open- and closed-aperture Z-scan techniques. The Ag NP–TAIPDI dye hybrid systems (Ag@TAIPDI nanocomposites) exhibited pronounced reverse saturable absorption and self-defocusing behavior, indicating a negative nonlinear refractive index. Both the nonlinear absorption coefficient and refractive index increased markedly with rising AgNP concentration, leading to a significant enhancement in the third-order nonlinear susceptibility. Fluorescence studies further revealed a concentration-dependent emission enhancement due to metal-enhanced fluorescence arising from surface plasmon resonance-induced local field amplification. The Ag@TAIPDI nanocomposites also demonstrated strong optical limiting performance, with the limiting threshold decreasing as the AgNP concentration increased. These findings highlight the synergistic role of plasmon–exciton coupling and thermal lensing in enhancing the nonlinear response of such nanocomposites. The results establish AgNPs–TAIPDI dye hybrid systems as promising materials for all-optical switching, optical limiting, and photonic device applications. Full article

Objective: This study aimed to obtain a core–shell chitosan–TiO₂ nanoparticle and to investigate its ability to inhibit Candida albicans biofilm formation when added to 3D-printed polymethyl methacrylate (PMMA) denture base resins. Materials and Methods: Ionic gelation was employed to prepare and characterize the nanoparticle, and Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction were used to identify the structure and morphology. Nanoparticle was added to 3D-printed denture resins at four different weight percentages (0.25%, 0.5%, 0.75%, and 1%) and antibiofilm activity was determined by carrying out Colony Forming Unite (CFU) counts after exposure to C. albicans. Results: The 0.25 wt.% chitosan–TiO₂ group exhibited a significant reduction in colony-forming units (CFUs) compared to the control (p < 0.05). Although higher nanoparticle concentrations showed improved biofilm formation, this was most likely caused by nanoparticle aggregation, which interfered with surface homogeneity and biofilm resistance. Conclusions: Incorporating a 0.25 wt.% core–shell chitosan–TiO₂ nanoparticle into 3D-printed denture base resin markedly improves its antibiofilm activity against Candida albicans while maintaining the material’s integrity. Full article

Replacing conventional chemical binders with natural polymers in geotechnically treated soil allows for the creation of more sustainable materials with both valuable ecological and mechanical properties. Xanthan gum and sodium alginate are natural polymers with excellent binding properties and water retention, which can help reduce carbon emissions. However, there is a lack of research on how to achieve optimal performance through the rational formulation of different biopolymers. This study investigates the use of these two natural biopolymers as binders (xanthan gum and sodium alginate) in slope-protection habitats treated with soil optimised using response surface methodology (RSM) within Design-Expert analysis software. The effects of xanthan gum concentration, sodium alginate concentration, and time, as well as their interactions on the properties of treated soil, ryegrass growth, and soil greenhouse gas emissions were evaluated, resulting in an optimized substrate formulation that balances good geotechnical properties with low environmental impact. Pot cultivation trials indicated that cohesion (c) and internal friction angle (φ) increased linearly with rising xanthan gum and sodium alginate concentrations, while the number of ryegrass plants (N_p) and root area ratio (RAR) decreased linearly with increasing binder concentration. Both CO₂ and CH₄ fluxes increased with rising binder concentrations. An analysis of variance (ANOVA) revealed that xanthan gum concentration had a stronger promoting effect on c and φ and a stronger inhibiting effect on N_p and RAR than sodium alginate. In contrast, sodium alginate concentration exhibited a stronger inhibitory effect on CO₂ and CH₄ fluxes. Through comprehensive optimization of geotechnical properties, vegetation growth, and greenhouse gas emissions, the optimal formulation was determined to be 0.885% for xanthan gum and 0.791% for alginate. The optimized composition resulted in increases of 38.6% and 19.1% for c and φ, respectively, while N_p and RAR increased by 7.7% and 15.0%, respectively. CO₂ and CH₄ fluxes decreased by 61.6% and 65.2%, respectively. This study contributes to advancing the sustainability of geotechnical treatments to favour vegetation regrowth. However, these materials will need to be further tested under field conditions to verify their effectiveness and duration. Full article

Aging underground pipeline infrastructure across the United States, including systems used for potable water supply, wastewater collection, and stormwater conveyance, has exceeded its intended service life, emphasizing the need for replacement or rehabilitation to maintain reliable service to communities. Among available trenchless technologies, cured-in-place pipe (CIPP) is widely applied because it minimizes surface disruption and is well-suited for use in densely populated areas. Despite these advantages, environmental concerns remain regarding the release of total volatile organic compounds (VOCs) during CIPP installation and curing. This study evaluates total VOC emissions from CIPP liners under field conditions. Air samples were collected at six installation sites across the United States before, during, and after installation and curing to quantify key VOC species. Multiple sampling methods were employed, including photoionization detectors (PIDs), Summa canisters, and personal worker sampling. The measured compounds included styrene, cumene, acetophenone, hexane, toluene, and ethanol. Measured concentrations were compared with occupational exposure limits established by the U.S. Environmental Protection Agency (USEPA), the National Institute for Occupational Safety and Health (NIOSH), and the Occupational Safety and Health Administration (OSHA). The results indicate that styrene was the dominant compound within active CIPP work zones, with peak concentrations reaching 25.5 ppm during curing. In contrast, VOC concentrations decreased substantially within five feet downwind of the work zone. Overall, the findings suggest that potential public exposure risks are limited, while workers directly involved in CIPP operations may experience elevated short-term exposures during installation and curing activities. Full article