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Photoelectric synergistic degradation of dye wastewater has been developed. In this experiment, we prepared Nitrogen-doped titanium dioxide-graphene/nickel foam (N/TiO 2 -Gr/F–Ni) by electrophoresis and impregnation methods, to degrade methyl orange (MO) aqueous solution. Firstly, nitrogen-doped titanium dioxide particle (N/TiO 2) was prepared by the sol-gel method, which showed a photocatalytic degradation catalytic kinetic constant of 1.8 × 10−2 min−1 under simulated sunlight. Meanwhile, graphene (Gr) was loaded on nickel foam (F–Ni) to prepare Gr/F–Ni electrode by electrophoresis method, which obtained a catalytic kinetic constant of 1.15 × 10−2 min−1 at 10 V. Finally, N/TiO 2 was loaded on Gr/F–Ni to prepare N/TiO 2 -Gr/F–Ni photoelectrode by electrophoresis and impregnation methods, which had a catalytic kinetic constant of 3.96 × 10−2 min−1 at 10 V and under 1 sun. The results show that there is a synergistic effect between light degradation and electro-Fenton oxidation because the bonding electrons in N/TiO 2 are activated to produce photogenerated electron-hole pairs. On the other hand, the separation efficiency of the photogenerated electron is enhanced by the Gr. [ABSTRACT FROM AUTHOR]

Heterogeneous void distribution is a common phenomenon in asphalt mixtures and is closely linked to their performance. Therefore, it is necessary to propose a physically meaningful and accurately fitting vertical void distribution model for asphalt mixtures, so as to realize the quantitative evaluation of void distribution. In this study, virtual and actual specimens of asphalt mixture were established using discrete element method (DEM), laboratory compaction, and field coring methods. The vertical void distribution of different specimens was obtained through CT scanning and image processing technology. The impact of various factors, including gradation type, nominal maximum aggregate size, and specimen height on void distribution, was investigated. Subsequently, a three-stage exponential model was proposed to characterize the vertical void distribution in asphalt mixture. The physical significance of different fitting parameters in the model was elucidated. The results indicate that the vertical void distribution of DEM models and laboratory compaction specimens exhibited a bathtub shape, while the vertical void distribution of pavement core specimens exhibited a semi-bathtub shape. The void distribution of the mixture was affected by gradation type, nominal maximum aggregate size and specimen height. The vertical void distribution of asphalt mixture could be effectively characterized by the three-stage exponential model. In addition, the root mean squared error of the second stage data from the three-stage exponential model was also proposed to evaluate the void distribution uniformity. • A three-stage exponential model was proposed to characterize the vertical void distribution. • The feasibility of the three-stage model was analyzed through simulation and test results. • An evaluation method for the uniformity of vertical void distribution was proposed. • The potential application of the three-stage exponential model was discussed. [ABSTRACT FROM AUTHOR]

Abstract: The phytoplankton assemblages’ patterns and their correlation to environmental factors were studied in Bohai Bay during spring and summer. Two zones, the northern (NWA) and southern (SWA) water area, were identified by cluster analysis based on their physical and chemical properties. Principal component analysis (PCA) showed that more phytoplankton species was found in the SWA with low nutrient concentration, while high phytoplankton abundance occurred in the NWA with high nutrient concentration. The seasonal variability in phytoplankton can be explained by water temperature, nutrient, and hydrodynamic conditions (includes mixing during spring and stratification during summer). Results of redundancy analysis (RDA) showed that silicate (SiO4) and soluble reactive phosphorus (SRP) were the most important environmental factors influencing the phytoplankton distribution during spring and summer, respectively. Hydrodynamics condition plays a key role in controlling variation of the environmental factors, which determined phytoplankton distribution in Bohai Bay. [Copyright &y& Elsevier]

• Glass microsphere was used to prepare low-thermal-conductivity asphalt mixture. • The thermal conductivity of asphalt mixture reduced by a maximum of 23.4%. • Glass microsphere negatively affected the road performances of asphalt mixture. To decrease the solar radiation heat entering the pavement, glass microsphere (GM) was selected as filler to replace limestone mineral filler (LMF) to improve the thermal resistance of asphalt mixture. The influence of GM on the thermal performance of asphalt pavement was studied by testing the thermal conductivity of asphalt mixture. It is found that the thermal conductivity could be reduced by 23.4%, which was beneficial to improve the cooling effect of asphalt pavement. A series of test, including dynamic repeated creep test, three-point bending test, dynamic modulus test and semi-circular bending test, were used to evaluate the influence of GM on the deformation resistance, low-temperature cracking resistance, dynamic performance and fatigue life of asphalt mixture. The results show that replacing LMF with GM negatively affected the above road performances of asphalt mixture. In further studies the actual rutting resistance of asphalt pavement with GM should be investigated by considering the cooled pavement structure and the elastic/creep performances of asphalt mixture. [ABSTRACT FROM AUTHOR]

• Glass microsphere was used to prepare thermal resistance asphalt mixture. • The thermal conductivity of asphalt mixture reduced by 23.8%. • The internal temperature of the thermal resistance pavement reduced. • The rutting depth of the middle and bottom layers reduced by a maximum of 8.5%. In this paper, glass microsphere (GM) was used to prepare thermal resistance asphalt mixture (TRAM) by replacing limestone mineral filler (LMF). The mixture was applied in the top layer of asphalt pavement to decrease the solar radiation transferring into asphalt pavement. The thermal, elastic and creep parameters of TRAM were obtained using a series of laboratory tests. Based on the above parameters, the heat transfer and rutting models of thermal resistance asphalt pavement (TRAP) were established. The results show that completely replacing LMF with GM in asphalt mixture resulted in thermal conductivity decreasing by 23.8% and specific heat capacity increasing by 10.6%. Compared with control asphalt pavement, the heat absorption of the designed pavement at the depth of 4 cm decreased by a maximum of 5.5% and the maximum temperature reduced up to 1.7 °C (at 12:00 p.m.). The cooling effect of thermal resistance pavement was verified by an indoor irradiation test. The rutting depth of the middle and bottom layers in the TRAP reduced by a maximum of 8.5% after 500 thousand times of standard axis load were applied. Due to the excellent thermal resistance effect, GM can be used to reduce the internal temperature of asphalt pavement and improve the rutting resistance of asphalt pavement. [ABSTRACT FROM AUTHOR]

The Yangtze River deepwater channel in the downstream of Nanjing China is the largest water transport project. It necessitates an effective ecological risk assessment of sediment–bound heavy metals driven by construction of the Yangtze River ship channel. We conducted a three–year field studies to investigate levels of heavy metals (Hg, Cd, Pb, Cu, and Zn), pH, and total phosphorus in sediments, as well as diversity of zoobenthos, phytoplankton, and zooplankton along the Taichang–Nantong reaches of the Yangtze River. Results showed that high–concentrations of Pb is at 130.62 mg/kg and of Hg is at 0.88 mg/kg in the sediments, which mainly emitted from the power electronics, power systems, and the hydrocarbon–based fuel combustion via principal component analysis. Based on optimized contamination indices for metals, we should consider their ecological risks when the potential ecological risk factor (E r i) of Hg is up to 210 in the basin. The channel construction resulted in significantly increasing concentrations and ecological risks of heavy metals at the lower reaches. Meanwhile, the community structure of aquatic organisms changed and the investigated species richness decreased significantly from 78 to 47 during the project. Through redundancy analysis, more significant variances of the plankton species richness (55% and 22%) were attributed to E r i of heavy metals and their combined risk index as compared with both planktonic and benthic organisms (52% and 17%). Moreover, the species density of both Melosira granulata and Navicula sp., major phytoplankton species in the basin, were significantly negatively correlated to Pb and Hg in sediments. Plankton was more sensitive indicators than zoobenthos due to the ability of plankton to reactivate and bioaccumulate sediment–bound heavy metals. This study innovatively warned management to control river engineering–induced ecological risks of metals in sediments and revealed their potential risk pathway of ingestion by sensitive plankton. Image 1 • Both pollution sources and toxicity mechanisms were identified to control risks. • Heavy metal risks were evaluated based on optimized ecological risk factors. • Ship channel construction cause impacts of heavy metals on aquatic ecosystem. • Community structural change was linked to risks posed by Hg and Pb in sediments. • Plankton were more sensitive than zoobenthos by ingestion of metals in sediments. [ABSTRACT FROM AUTHOR]

Stabilizers are commonly employed in SBS-modified asphalt, yet their specific impact on aging behavior remains ambiguous. Past studies have not agreed on their role and have primarily examined effects on the SBS polymer phase, neglecting asphalt phase influences. Understanding these interactions is essential for aging mechanisms and rejuvenation strategies. To solve this issue, this study compared three types of asphalt to analyze their properties during aging. Microscopic tests comprising morphology, chemical structure, and molecular weight analyses with nine quantitative indicators were conducted, and the distinct influences of stabilizers on asphalt and SBS polymer phases were elucidated. The results revealed that the change rate in the physical properties of SBS-modified asphalt during aging decreases with sulfur addition, rheological parameters indicated that sulfur predominantly protects the polymer network structure from degradation during short-term aging. Furthermore, stabilizers had no explicit impact on the carbonyl index but could delay the generation of asphaltene molecules during aging, the change rates of asphaltene% were 1.65% without stabilizers and 12.36% with them after TFOT (Thin film oven test) aging. Stabilizers also notably mitigated polymer degradation and exhibited beneficial effects even during PAV (Pressure aging vessel) aging. The overall findings contribute to a clearer understanding of the complex interplay among the various components of SBS-modified asphalt, such as base asphalt, SBS modifiers, and stabilizers, providing theoretical insights into aging mechanisms and rejuvenation strategies involving stabilizers. • The role and contributions of stabilizers in the aging process of SBS-modified asphalt thoroughly were analyzed. • The distinct effects of stabilizers on the asphalt phase and polymer phase after aging were examined. • Stabilizers could delay the generation of asphaltene molecules during aging. [ABSTRACT FROM AUTHOR]

Since the correlation between the meso-structure composition and force chain transmission of asphalt mixtures, it has a significant impact on the evaluation and utilization of their material properties. Based on the discrete element method, this paper studied the internal force chains transmission mechanism of asphalt mixture under indirect tensile mode, and quantitatively analyzed the composition and distribution of the force chains. An aggregate template library for asphalt mixture was constructed using image segmentation and clump generation algorithm. Indirect tensile simulation was achieved by assigning relevant parameters, indicating a good correlation with laboratory tests. The tensile and compressive chain fields inside asphalt mixtures were visualized and characterized. The concept of strong and weak force chains was proposed, and statistical methods was used to analyze the strength, distribution, and evolution of force chains. The force transfer mechanisms of different components of asphalt mixtures have been elucidated, providing a research tool for their structural design and performance evaluation. • The aggregate template library was constructed within PFC3D. • Virtual indirect tensile test was built to analyze mechanical property. • The probability and distribution of the force chains were proposed. • The evolution law of the force chains was clarified. [ABSTRACT FROM AUTHOR]