Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025102801
This study develops a multivariate time-series forecasting model for water quality in the Lhasa River, focusing on four key indicators: water temperature, pH, dissolved oxygen, and turbidity. Data preprocessing integrated multiple missing-value imputation strategies and interquartile range (IQR) outlier removal. Boxplots and relative standard deviation (RSD) assessed data distribution and dispersion, while autocorrelation and Pearson correlation analyses revealed periodic patterns and inter-variable relationships. Four representative algorithms—Support Vector Regression (SVR), Extreme Gradient Boosting (XGBoost), CNN-BiLSTM-Attention, and TCN-Transformer—were optimized via Bayesian hyperparameter tuning. Model performance was evaluated using MAE, MSE, RMSE, and R². The study systematically compared the effects of different missing-value handling methods, both independently and combined with IQR outlier removal. Results indicate that CNN-BiLSTM-Attention excels in water temperature prediction, suitable for relatively stable and simple patterns. In contrast, TCN-Transformer demonstrates superior performance for pH, dissolved oxygen, and turbidity, which exhibit strong nonlinearity and long-term dependencies, effectively capturing temporal dependencies and coupling relationships. The findings provide a viable technical route and theoretical reference for river water quality monitoring and intelligent early-warning systems.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202607005
To optimize municipal sludge incineration and enhance disposal efficiency, sludge from the First Sewage Treatment Plant in Chengdu was analyzed via synchronous thermal analysis (TG-DTG-DSC) in air at 20 K/min. The combustion process comprised four stages: moisture evaporation (35–150 °C), volatile combustion (150–400 °C), fixed carbon combustion (400–600 °C), and burnout (600–1000 °C). Ignition and burnout temperatures were 220.7 °C and 605.9 °C, respectively, with a comprehensive combustion characteristic index of 6.32×10⁻⁸ %²/(min²·K³), indicating good stability. Kinetic analysis using Coats-Redfern (CR) integral and Achar-Brindley-Sharp (ABS) differential methods showed deviations below 15%, confirming CR reliability. Moisture evaporation and volatile combustion followed first-order models (F1) with activation energies of 52.24 and 48.81 kJ/mol, while fixed carbon combustion and burnout followed second-order models (F2) with activation energies of 192.38 and 102.27 kJ/mol. Thermodynamic parameters (ΔH: 49.06, 43.59, 185.94, 95.00 kJ/mol; ΔS: -148.36, -211.63, -30.74, -201.38 J/mol·K; ΔG: 105.76, 176.52, 209.74, 271.04 kJ/mol) revealed negative entropy and positive Gibbs free energy across all stages, indicating external energy dependence, with the highest demand in the burnout stage. These findings provide a theoretical basis for optimizing incineration process parameters and energy recovery.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-4012-4
Stimuli-responsive fluorescent hydrogels, owing to their tunable optical properties and unique smart response characteristics, have significant potential in encryption applications and information security. However, most current systems are limited to single-stimulus responsiveness and lack the capability for programmable information erasure or multi-modal dynamic synergy. Hence, we propose a multi-stimuli-responsive phase-change hydrogel incorporating aggregation-induced emission hydrophobic carbon dots (AIE-HCDs) and polyethylene glycol (PEG)-cellulose network, demonstrating dynamic fluorescence chromism under various external triggers. The hydrogel exhibits solvent-exchange-triggered fluorescence color changes from blue to red, enabled by the concentration modulation of AIE-HCDs through the exchange between PEG and water. Additionally, the temperature-induced phase transition of PEG from crystalline to molten state modulates the aggregation and dispersion of AIE-HCDs, thereby enabling dynamic fluorescence color changes. The phase transition further confers excellent shape-memory behavior and adjustable mechanical properties, with the tensile modulus varying from 6.28 MPa in the molten state to 36.23 MPa in the crystalline state, while maintaining high transparency (~88% in the molten state). By utilizing micro-contact printing and the multi-stimulus response, an encryption platform enables information to be hidden, selectively read under sequential stimuli (thermal, UV, and solvent), and completely erased upon demand. This strategy demonstrates significant potential for advancing high-level information encryption and anti-counterfeiting technologies.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3526-5
Polymer-based positive temperature coefficient (PTC) composites exhibit temperature-responsive resistivity, yet conventional systems with Curie temperatures (Tc) above 50 °C fail to meet the precision thermal management demands of room-temperature electronics. This study presents a ternary composite wherein carbon black (CB) is selectively localized within a myristyl alcohol (MA) phase, stabilized by an ethylene vinyl acetate (EVA) matrix. The reversible solid-liquid transition of MA dynamically disrupts and reconfigures CB conductive networks, while EVA elasticity suppresses phase migration at elevated temperatures. The optimized MA/EVA/CB composite achieves a low Tc of 35 °C, ultralow initial resistivity (ρin) of 50 Ω cm, high PTC intensity (PTCI = 7.0), and exceptional cycling stability with >95% resistivity retention after 100 thermal cycles. Even after 14 days of real space-environment exposure, the composite maintains ultralow resistivity and high PTCI. Differential scanning calorimetry and Fourier-transform infrared spectroscopy confirm molecular integrity under extreme conditions. Microstructural analysis reveals that MA melting/crystallization governs conductive network disruption and reconfiguration. A self-regulating heater fabricated from this composite stabilizes an aluminum block at 30.6 ± 0.03 °C under 20 V in a −10 °C environment without external control. These low-Tc PTC composites offer transformative potential for adaptive thermal management in aerospace electronics.