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Dissolved organic matter (DOM) can affect the transformation of pollutants through photosensitization, but most current research focuses on hydrophilic pollutants, making it such that less attention is paid to hydrophobic pollutants. In this paper, the effect and action mechanism of coexisting DOM on the photodegradation of decachlorobiphenyl (PCB-209) on suspended particles collected from the Yellow River were systematically investigated in a heterogeneous system using DOM standards and model compounds. Through molecular probe experiments, mass spectrometry analysis and theoretical calculations, we found that the excited triplet state of DOM (3DOM*) could excite PCB-209 to undergo dechlorination reaction. Due to the different modes of electron transition, the presence of carbonyl groups decreased the energy of 3DOM*, whereas the electron-donating groups made the energy of 3DOM* higher. DOM containing phenolic hydroxyl groups led to a higher steady-state concentration of •OH, and DOM containing phenyl ketone structures had a stronger ability to produce •O2–. Compared with aqueous •OH, •O2–produced from hydrophobic microregions could react more readily with PCB-209. This study deepens the understanding of the role of different functional groups of DOM in the photosensitized transformation of hydrophobic compounds.

An in-depth study of the degradation of bisphenol S (BPS) by both single-walled carbon nanotubes and heat activated persulfate (PS) was conducted in detail. The effects of various factors, namely, material dosage, initial substrate concentration, initial pH and the water matrix, on the removal of BPS were evaluated, and 10 μM BPS was completely removed in 90 min under the optimal conditions of [BPS]0 : [PS]0= 1 : 100, T= 25 °C, pH0= 7.0, and [N-SWCNTs] = 20 mg L−1. Fast removal of BPS was also obtained when the reaction temperature reached 65 °C without catalyst. There were 15 intermediates identified in total, and hydroxylation, sulfate addition, carboxylation, S–C bond cleavage and polymerization were considered to be the main transformation pathways of BPS in both the systems based on LC-MS analysis. The discrepancy in the proportion of hydroxyl and sulfate radicals involved in the two systems led to different distribution and abundance of the observed products. According to quantum chemical calculations, hydroxylation, hydrogen atom abstraction and sulfate addition occurred as the initial reactions between radicals and BPS. Furthermore, the intrinsic reaction coordinate (IRC) paths of the generated primary products were obtained using the program Gaussian 09. Low reaction barriers (22.20, 25.06 and 13.85 kJ mol−1, respectively) revealed that the H atom linked to the phenoxy group and the ortho-C of BPS were the most likely sites to react. The present work reveals the overall transformation behavior of BPS in a radical-triggered PS system by combining experimental and theoretical study.

ABSTRACTThe migration of vascular smooth muscle cells (VSMCs) from the media to the intima is proposed to be a key event in the development of atherosclerosis. Recently, we reported that Chlamydia pneumoniaeinfection is involved in VSMC migration. However, the exact mechanisms for C. pneumoniaeinfection-induced VSMC migration are not yet well elucidated. In this study, we examined the role of the Toll-like receptor 2 (TLR2) activation-related signaling pathway in VSMC migration induced by C. pneumoniaeinfection. An Affymetrix-based gene expression array was conducted to identify the changes of gene expression in rat primary VSMCs (rVSMCs) infected with C. pneumoniae. Both the microarray analysis and quantitative real-time reverse transcription (RT)-PCR revealed that TLR2 mRNA expression was strongly upregulated 12 h after C. pneumoniaeinfection. RT-PCR and Western blot analysis further showed that the expression levels of TLR2 mRNA and protein significantly increased at the different time points after infection. Immunocytochemical analysis suggested a TLR2 recruitment to the vicinity of C. pneumoniaeinclusions. Cell migration assays showed that the TLR2-neutralizing antibody could significantly inhibit C. pneumoniaeinfection-induced rVSMC migration. In addition, C. pneumoniaeinfection stimulated Akt phosphorylation at Ser 473, which was obviously suppressed by the PI3K inhibitor LY294002, thereby inhibiting rVSMC migration caused by C. pneumoniaeinfection. Furthermore, both the infection-induced Akt phosphorylation and rVSMC migration were suppressed by the TLR2-neutralizing antibody. Taken together, these data suggest that C. pneumoniaeinfection can promote VSMC migration possibly through the TLR2-related signaling pathway.