Search Results (342)

This paper reviews constitutive models used to predict concrete spalling under elevated temperatures, with emphasis on fire exposure and concrete linings in deep geological repositories for spent fuel and nuclear waste. The review synthesizes (1) how material composition (ordinary Portland cement concrete, geopolymer concrete, and fiber-reinforced systems using polypropylene and steel fibers) affects spalling resistance; (2) how coupled environmental and mechanical actions (temperature, moisture, stress state, chloride ingress, and radiation) drive damage initiation and spalling; and (3) how constituent-scale characteristics (microstructure, porosity, permeability, elastic modulus, and water content) govern thermal–hydro–mechanical–chemical (THMC) transport and damage evolution. We compare major constitutive modeling frameworks, including plasticity–damage models (e.g., concrete damage plasticity), statistical damage approaches, and fully coupled THM/THMC formulations, and highlight how key parameters (e.g., water-to-binder ratio, temperature-driven pore-pressure gradients, and crack evolution laws) control predicted spalling onset, depth, and timing. Several overarching challenges emerge: lack of standardized experimental protocols for spalling tests and assessments, which limits cross-study benchmarking; continued debate on whether spalling is dominated by pore pressure, thermo-mechanical stress, or their interaction; limited integration of multiscale and constituent-level material characteristics; and high data and computational demands associated with advanced multi-physics models. The paper concludes with targeted research directions to improve model calibration, validation, and performance-based design of concrete systems for high-temperature and repository applications. Full article

Considering the challenges of decarbonization, the energy transition, and the necessity to increase resource efficiency in the context of the circular economy, there is a need to develop sustainable solutions for the material and energy use of biogenic waste. Biogenic waste, which remains underutilized and can be regarded as an untapped resource, offers significant potential for sustainable energy production. In this context, biogas plants are a key technology, as they convert biogenic waste into renewable energy, reduce greenhouse gas emissions, and contribute to closing material cycles. The standardized life cycle assessment (LCA) methodology is a tool for the systematic analysis and evaluation of environmental impacts of products, systems, or services. The objective of this study is to develop a methodological and conceptual framework for the LCA of the innovative biogas plant based on a rotating drum fermenter. The environmental aspects of biowaste utilization and the role of the biogas plant in waste reduction and energy production are discussed in the broader context of the circular economy. Due to its complexity, this paper considers LCA with focus on the definition of the goal and scope of the study in accordance with international standards. Full article

Drinking-water treatment systems must effectively control natural organic matter (NOM), a major precursor of regulated disinfection by-products (DBPs). Specific ultraviolet absorbance (SUVA) is widely used as an operational surrogate for NOM aromaticity and hydrophobicity; however, ozonation and subsequent filtration can disrupt the linear relationship between SUVA and trihalomethane formation potential (THMFP). This study evaluates whether SUVA can reliably predict THMFP under two ozonation configurations frequently applied in drinking-water treatment: pre-ozonation prior to coagulation–filtration and final ozonation following filtration. Experimental data were analyzed using conventional linear regression and artificial neural network (ANN) models, with SUVA employed as the sole predictor variable. Across all treatment configurations, reductions in SUVA were consistently more pronounced than corresponding decreases in THMFP, indicating a decoupling between chromophoric loss and chlorine-reactive precursor dynamics under ozonation-dominated conditions. Linear regression models exhibited only moderate predictive performance (R² = 0.63–0.76), reflecting the limitations of proportional surrogate-based approaches when NOM undergoes oxidative and adsorptive transformation. In contrast, single-parameter ANN models captured the nonlinear SUVA–THMFP relationship with substantially higher accuracy across both pre- and final-ozonation regimes (R² = 0.88–0.99), successfully resolving process-dependent patterns embedded within optically compressed SUVA signals. These findings demonstrate that, although SUVA alone cannot linearly represent the multistep transformation of NOM during ozonation and adsorption, it retains process-relevant structure information on DBP precursor reactivity that can be effectively extracted using nonlinear modelling. The results highlight the potential of integrating ANN-driven tools into advanced monitoring and DBP-control strategies in modern drinking-water treatment systems. Full article

Freeze–thaw cycles (FTCs) are a prevalent weathering process that threatens the stability of canal slopes in seasonally frozen regions. This study combines direct shear tests under multiple F-T cycles with coupled thermo-hydro-mechanical numerical modeling to investigate the failure mechanisms of slopes with different moisture contents (18%, 22%, 26%). The test results quantify a marked strength degradation, where the cohesion decreases to approximately 50% of its initial value and the internal friction angle is weakened by about 10% after 10 freeze–thaw cycles. The simulation reveals that temperature gradient-driven moisture migration is the core process, leading to a dynamic stress–strain concentration zone that propagates from the upper slope to the toe. The safety factors of the three soil specimens with different moisture contents fell below the critical threshold of 1.3. They registered values of 1.02, 0.99, and 0.78 within 44, 44, and 46 days, which subsequently induced shallow failure. The failure mechanism elucidated in this study enhances the understanding of freeze–thaw-induced slope instability in seasonally frozen regions. Full article

Global environmental changes significantly alter ecosystem services (ESs), particularly in fragile regions like the Tibetan Plateau. While methodological advances have improved spatial assessment capabilities, understanding of how multiple drivers interact to shape ecosystem service heterogeneity remains limited to regional scales, especially across complex alpine landscapes. This study aims to clarify whether multi-factor interactions produce nonlinear enhancements in ES explanatory power and how these driver–response relationships vary across heterogeneous terrains. We quantified spatiotemporal patterns of four key ecosystem services—water yield (WY), soil conservation (SC), carbon sequestration (CS), and habitat quality (HQ)—across the southeastern Tibetan Plateau from 2000 to 2020 using multi-source remote sensing data and spatial econometric modeling. Our analysis reveals that SC increased by 0.43 t·hm⁻²·yr⁻¹, CS rose by 1.67 g·m⁻²·yr⁻¹, and HQ improved by 0.09 over this period, while WY decreased by 3.70 mm·yr⁻¹. ES variations are predominantly shaped by potent synergies, where interactive explanatory power consistently surpasses individual drivers. Hydrothermal coupling (precipitation ∩ potential evapotranspiration) reached 0.52 for WY and SC, while climate–vegetation synergy (precipitation ∩ normalized difference vegetation index) achieved 0.76 for CS. Such climate–restoration synergies now fundamentally shape the region’s ESs. Geographically weighted regression (GWR) further revealed distinct spatial dependencies, with southeastern regions experiencing strong negative effects of land use type and elevation on WY, while northwestern areas showed a positive elevation associated with WY but negative effects on SC and HQ. These findings highlight the critical importance of accounting for spatial non-stationarity in driver–ecosystem service relationships when designing conservation strategies for vulnerable alpine ecosystems. Full article

Screening is a critical link in the separation of gold ores. However, issues such as the agglomeration of material masses and screen aperture blinding often lead to low screening precision and poor desliming performance, severely impacting the efficiency of subsequent crushing processes. To address these challenges, this paper proposes a rigid–flexible coupled screening method for viscous and moist gold ores. The time-frequency response characteristics of the screen surface motion were investigated, the influence of processing capacity and moisture content on screening performance was analyzed, and an industrial performance evaluation of the rigid–flexible coupled screen surface was conducted. Laboratory and industrial test results demonstrate that the rigid–flexible coupled screen surface exhibits a periodic, non-regular waveform with a maximum peak vibration intensity of 14.79 g. Screening efficiency is synergistically inhibited by moisture content and processing capacity. When the ore moisture content is below 3% and the processing capacity ranges from 15 to 22.5 t/(h·m²), the screening efficiency can exceed 85%. Compared with conventional screen surfaces, the implementation of the rigid–flexible coupled screen surface achieved a desliming efficiency of 91%, a maximum processing capacity in the crushing stage of 380 tons per hour, a nearly 12% improvement in the screening efficiency of the closed-circuit checking process for crushed products, and an approximately 8% reduction in the circulating load ratio of the crushing circuit. These enhancements collectively ensure the stable operation of both the screening and crushing processes. Full article

Cyanobacterial blooms pose significant threats to aquatic ecosystems and drinking water safety, primarily through the release of diverse secondary metabolites. This study systematically explored the dynamics of secondary metabolites in Microcystis aeruginosa and Anabaena sp. under controlled conditions, focusing on the effects of temperature (10 °C, 25 °C, 35 °C) and growth phases (exponential, stationary, decline). Key parameters measured included cell density, dissolved organic carbon (DOC), microcystins (MC-LR, MC-RR), taste and odor compounds (β-cyclocitral, β-ionone), and disinfection by-product formation potentials (trihalomethanes (THMs) and haloacetic acids (HAAs)). Results revealed striking interspecific differences: M. aeruginosa exhibited significantly higher metabolite production, with peak DOC, extracellular MC-LR, and particulate β-cyclocitral observed in the decline phase at 25–35 °C. In contrast, Anabaena sp. showed an “early accumulation advantage” for THM precursors and “residual release” in the decline phase. Temperature played a critical regulatory role, with 25 °C as the optimal for most metabolites, while 35 °C enhanced extracellular release of dissolved β-cyclocitral in M. aeruginosa. Growth phase dynamics were consistent across species, with stationary and decline phases marked by elevated metabolite concentrations due to intensified synthesis and cell lysis, particularly for HAAs. These findings highlight species-specific metabolic strategies and their environmental drivers, providing critical insights for assessing and managing cyanobacterial bloom risks in aquatic ecosystems. Full article

Paddy field leveling is the foundation of high-yield rice cultivation. In response to the current issues of low leveling accuracy and the lack of efficient multi-operation machinery, an Integrated Multi-operation Paddy Field Leveling Machine was designed in this study. This machine can complete soil crushing, stubble burying, mud stirring, and leveling in a single pass. Combined with an adaptive control system based on Global Navigation Satellite System—Real-Time Kinematic (GNSS-RTK) technology, it enables adaptive and precise paddy field leveling operations. To verify the operational performance of the equipment, field tests were conducted. The results showed that the machine achieved an average puddling depth of 14.21 cm, a surface levelness of 2.16 cm, an average stubble burial depth of 8.15 cm, and a vegetation coverage rate of 89.33%, demonstrating satisfactory leveling performance. Furthermore, to clarify the feasibility and superiority of applying this equipment in actual rice production, experiments were conducted to investigate the effects of different field leveling methods on early rice growth, yield, and its components. One-way analysis of variance was employed to examine the differences in agronomic indicators between the different field leveling treatments. The results indicated that using this equipment for paddy field leveling, compared to traditional methods and dry land preparation, can improve the seedling emergence rate, thereby laying a solid population foundation for the formation of effective panicles. It also promoted root growth and development and increased the total dry matter accumulation at maturity, thereby contributing to high yield formation. Over the two-year experimental period, the rice yield remained above 9.8 t·hm⁻². This research provides theoretical support and practical guidance for the further optimization and development of subsequent paddy field preparation equipment, thereby promoting the widespread application of this technology in rice production. Full article

LACMA’s 19th-century Tibetan Altar Table with Auspicious Symbols is characterized by a complex stratigraphy comprising animal glue-based ground and paint layers, a presumably original tung oil-based varnish, and a dark surface layer composed of a complex mixture of paraffinic wax, shellac, and rapeseed oil, which obscures the object’s original decorative scheme. This study examines the use of nanostructured fluids and organic solvents confined within hydrogels and organogels for the selective removal of the dark surface layer while preserving the underlying paint and varnish. Following the analysis of the artwork’s constituent materials, cleaning tests were conducted and evaluated using visible and ultraviolet fluorescence (UVF) imaging, spectrophotometry, and digital microscopy. The homogeneous absorption of solvent mixtures by the organogels was assessed through gas chromatography–mass spectrometry (GC–MS). Results indicate that confining cleaning fluids within the gels’ porous networks significantly improved solvent retention and control of fluid release. While conventional cleaning methods proved insufficiently selective, the gradual release of a nanostructured fluid containing a small amount of benzyl alcohol, combined with the nanostructural properties of the poly(vinyl alcohol)–sebacic acid (PSA2) hydrogel, enabled targeted removal of the surface layer while preserving the integrity of the underlying layers. Full article

The biological control of SWD using entomopathogenic viruses offers a sustainable alternative to chemical insecticides; however, viral instability under environmental and digestive conditions limits their application. Here, we present a chitosan–TPP encapsulation system designed to protect and control the release of Drosophila C virus (DCV) and La Jolla virus (LJV). Physicochemical characterization by dynamic light scattering (DLS) and zeta potential measurements confirmed successful encapsulation and indicated that stable electrostatic complexes form within a narrow pH range where chitosan is positively charged and the virion surface is negatively charged. The encapsulated viruses remained intact under acidic conditions but were rapidly released under alkaline conditions mimicking the posterior midgut of SWD. Encapsulation efficiency increased with decreasing chitosan molecular weight and higher stirring speed, reaching up to 90%. Bioassays demonstrated that both formulated viruses caused high mortality in adult flies, with no adverse effects from the carrier matrix. These findings establish chitosan–TPP formulations as an effective strategy for virus stabilization and targeted release in biological pest control. Full article

Real-time monitoring is essential for maintaining water quality and optimizing aquaculture productivity. Ion-selective electrodes (ISEs) are widely used to measure key parameters such as pH, nitrate, and dissolved oxygen in aquatic environments. However, these sensors are prone to fouling, the non-specific adsorption of organic, inorganic, and biological matter, which leads to potential drift (e.g., 1–10 mV/h), loss of sensitivity (e.g., ~40% in 20 days), and reduced lifespan (e.g., 3 months), depending on membrane formulation and environmental conditions. This review summarizes current research from mostly the last two decades with around 150 scientific studies on fouling phenomena affecting ISEs, as well as recent advances in fouling detection, cleaning, and antifouling strategies. Detection methods range from electrochemical approaches such as potentiometry and impedance spectroscopy to biochemical, chemical, and spectroscopic techniques. Regeneration and antifouling strategies combine mechanical, chemical, and material-based approaches to mitigate fouling and extend sensor longevity. Special emphasis is placed on environmentally safe antifouling coatings and material innovations applicable to long-term monitoring in aquaculture systems. The combination of complementary antifouling measures is key to achieving accurate, stable, and sustainable ISE performance in complex water matrices. Full article

Neonicotinoid insecticides (NNIs) are globally pervasive, and toxicological evidence indicates potential adverse effects from low-dose exposure in non-targeted organisms. Humans may be exposed to NNIs through multiple pathways, such as ingestion and inhalation, with dietary intake recognized as the dominant exposure route. However, longitudinal evidence characterizing evolving exposure patterns in rural children remains scarce. We evaluated temporal trends and dietary determinants of NNI exposure among 643 children at ages 7, 10, and 14 years in the Sheyang Mini Birth Cohort Study. Twelve NNIs and six metabolites in urine samples were measured using UPLC-HRMS; estimated daily exposure doses and hazard index (HI) were calculated, and linear mixed models were used to evaluate dietary determinants of NNI exposure. Widespread exposure was observed (ΣNNIs detection: 98.8–100%), and although cumulative risks remained below safety thresholds, both medians and upper bounds of HI increased with age (0.0007 to 0.0074; 0.2045 to 0.4054). Notably, exposure composition shifted, with declining imidacloprid and emerging dominance of clothianidin (CLO) and thiamethoxam (THM). Fruit and vegetable intakes were positively associated with ΣNNIs, whereas cereals, poultry, and eggs showed inverse associations, with more pronounced effects observed in boys. These findings indicated persistent yet evolving exposure risks in school-aged children, highlighting fruits and vegetables as major contributors. Although current toxicological risk appears low, the transition toward CLO and THM—compounds with limited chronic toxicity data—underscores the need for continued biomonitoring and targeted exposure mitigation. Full article

Accurate suction control underpins thermo-hydro-mechanical (THM) characterization of unsaturated soils, yet conventional polyethylene-glycol (PEG) osmotic methods suffer from membrane degradation, polymer intrusion, and marked temperature sensitivity. This study evaluates a potassium-neutralized poly (acrylamide-co-acrylic acid) hydrogel (PP) as a high-suction osmotic medium for water-retention testing of compacted kaolin using a sealed cell with a grade-42 filter paper separator (no semi-permeable membrane). The water-activity–suction relation of PP was calibrated with a chilled-mirror hygrometer (WP4C) over the high-suction domain, and temperature effects were assessed between 20–30 °C. The PP imposed stable target suctions across the practical engineering range, with cross-validation to WP4C of R² ≈ 0.985 and RMSE ≈ 0.09 MPa, and exhibited modest thermal sensitivity (~2–3% per 10 °C). Mass–time records showed a two-regime equilibration (rapid first-day moisture loss then slowing to asymptote), with time to 95% equilibrium t₉₅ ≈ 3–7 days depending on suction, and equilibrium within ~2 weeks under a normalized mass change, ${\displaystyle \frac{1}{m}}\left|{\displaystyle \frac{∆m}{∆t}}\right|<{\displaystyle \frac{0.1\%}{24h}}$ criterion. The resulting kaolin water-retention curves are smooth soil moisture factor (SMF) reproducible, and exhibited minor wetting–drying hysteresis (~20–25% gap at matched suctions). Collectively, the results indicate that PP provides a practical, membrane-free (in the semi-permeable sense) and accurate means to control high-range suction for unsaturated soil testing, showing only modest suction variations within the tested 20–30 °C range, while mitigating long-standing PEG limitations and simplifying laboratory workflows. Full article

This paper presents a practical and auditable methodology for prioritizing drinking water hazards based on fuzzy preference relations (FPR). The method is based on additive pairwise comparisons of tap water quality parameters, which are aggregated (median) into a complete preference matrix. For each parameter, a Fuzzy Priority Index (FPI) was determined as the average “advantage” over the others. The FPI values were mapped to five fuzzy priority levels (very low–very high) using triangular/trapezoidal membership functions, followed by a defuzzification process using the centroid of singletons (COGS) method. The final step is to map the categories to operational actions, ensuring a clear transition from assessment to decision (from routine monitoring to immediate intervention). The method was demonstrated on nine parameters that are relevant for regulatory (WHO/DWD) and operational purposes: As, Pb, THM, NO₃⁻, Hg, Cr, Mn, Cu, Fe. Thirty-six pairwise assessments were determined, which, after aggregation, formed fuzzy relations. The resulting ranking (FPI) is: As (0.76) > Pb (0.70) > THM (0.64) > NO₃⁻ (0.56) > Hg (0.50) > Cr (0.43) > Mn (0.36) > Cu (0.30) > Fe (0.25). Fuzzy categorization assigned As, Pb, THM to the High level, NO₃⁻, Hg, Cr to Medium, and Mn, Cu, Fe to Low, with the Score reflecting the “proximity” of higher levels. The approach is transparent, replicable, and supports sensitivity analysis. The combination of FPI with fuzzy categorization and a decision map transforms expert knowledge and uncertainty into prioritized, actionable steps for water safety management. Full article

This study, conducted with a rigorous statistical analysis, aims to assess the applicability of current analytical models in predicting the likelihood of splitting in precast concrete tunnel segments during the thrust phase of tunnel boring. Five analytical models were analyzed and compared to experimental results. The accuracy and precision of the models in predicting the splitting load were evaluated. The study revealed that the prediction accuracy of the models can be affected by various factors, such as the size and geometry of the test specimens and the type of test configuration used. An adjustment to the analytical models with the best performance is proposed to correct for statistical bias and enhance the predictions to address this issue. These findings are significant for the construction industry, as improved cracking control can reduce repair costs. Furthermore, enhancing the predictability of analytical models can improve the safety and reliability of precast concrete tunnel segments during tunnel boring. Full article