Degradation kinetics and disinfection by-products formation of benzophenone-4 during UV/persulfate process.

The degradation kinetics, reaction pathways, and disinfection by-products formation of an organic UV filter, benzophenone-4 (BP4) during UV/persulfate oxidation were investigated. BP4 can hardly be degraded by UV alone, but can be effectively decomposed by UV/persulfate following pseudo-first order kinetics. BP4 degradation rate was enhanced with increasing persulfate dosage and decreasing pH from 8 to 5. However, the degradation rate of BP4 at pH 9 was higher than that at pH 8 because of the presence of phenolic group in BP4 structure. and SO4-⋅ were confirmed as the major contributors to BP4 decomposition in radical scavenging experiments, and the second-order rate constants between HO⋅ and BP4 as well as those between SO4-⋅ and BP4 were estimated by establishing and solving a kinetic model. The presence of Br- and humic acid inhibited the decomposition of BP4, while NO3- promoted it. The mineralisation of BP4 was only 9.1% at the persulfate concentration of 50 µM. Six degradation intermediates were identified for the promulgation of the reaction pathways of BP4 during UV/persulfate oxidation were proposed as a result. In addition, the formation of DBP in the sequential chlorination was evaluated at different persulfate dosages, pH values, and water matrix. The results of this study can provide essential knowledge for the effective control of DBP formation with reducing potential hazard to provide safe drinking water to the public.

BP4 can be effectively degraded by UV/persulfate process, following pseudo-first order kinetics.OH⋅ and SO4−⋅ were identified as the main contributors to BP4 degradation during UV/persulfate process.The degradation pathways of BP4 during UV/persulfate process were proposed.Initial persulfate concentration and solution pH both affected the yield of DBPs.The higher toxic DBPs can be generated in the presence of Br− or NO3−.

Wavelength dependency and photosensitizer effects in UV-LED photodegradation of iohexol.

Iodinated X-ray contrast media (ICM) are ubiquitously present in water sources and challenging to eliminate using conventional processes, posing a significant risk to aquatic ecosystems. Ultraviolet light-emitting diodes (UV-LED) emerge as a promising technology for transforming micropollutants in water, boasting advantages such as diverse wavelengths, elimination of chemical additives, and no induction of microorganisms' resistance to disinfectants. The research reveals that iohexol (IOX) degradation escalates as UV wavelength decreases, attributed to enhanced photon utilization efficiency. Pseudo-first-order rate constants (kobs) were determined as 3.70, 2.60, 1.31 and 0.65 cm2 J-1 at UV-LED wavelengths of 255, 265, 275 and 285 nm, respectively. The optical properties of dissolved organic matter (DOM) and anions undeniably influence the UV-LED photolysis process through photon competition and the generation of reactive substances. The influence of Cl- on IOX degradation was insignificant at UV-LED 255, but it promoted IOX degradation at 265, 275 and 285 nm. IOX degradation was accelerated by ClO2-, NO3-and HA due to the formation of various reactive species. In the presence of NO3-, the kobs of IOX followed the order: 265 > 255 > 275 > 285 nm. Photosensitizers altered the spectral dependence of IOX, and the intermediate photoactivity products were detected using electron spin resonance. The transformation pathways of IOX were determined through density functional theory calculations and experiments. Disinfection by-products (DBPs) yields of IOX during UV-LED irradiation decreased as the wavelength increased: 255 > 265 > 275 > 285 nm. The cytotoxicity index value decreased as the UV-LED wavelength increased from 255 to 285 nm. These findings are crucial for selecting the most efficient wavelength for UV-LED degradation of ICM and will benefit future water purification design.

Effects of thyroid hormone on macrophage dysfunction induced by oxidized low-density lipoprotein / 生理学报

It has been recognized that patients with hypothyroidism have higher risks of atherosclerosis and coronary heart disease, however, the mechanisms are largely unknown. Considering that macrophage dysfunction plays an important role in the formation and development of atherosclerosis plaques, this study aimed to investigate the direct effects of thyroid hormone on macrophage functions and to provide new insight for the mechanism of hypothyroid atherosclerosis. RAW264.7 cells (mouse leukaemic monocyte macrophage cell line) were incubated with oxidized low-density lipoprotein (oxLDL) to establish macrophage foam cells model in vitro, and the protective effects of different concentration of thyroxine (T4) on the macrophage foam cells function were explored. The proliferation, migration and cell aging of macrophages were detected by MTT method, scratch test and β-galactosidase staining respectively. The ELISA method was used to detect the secretion of tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and interleukin-1β (IL-1β). Western blot analysis was applied to measure the phosphorylation of focal adhesion kinase (FAK), which was required for the process of proliferation and migration of macrophages. The results showed that oxLDL significantly inhibited the macrophage proliferation and migration, induced cell senescence, and promoted the secretion of TNF-α, MCP-1, and IL-1β; while T4 reversed those effects of oxLDL on macrophage in a concentration-dependent manner. Moreover, oxLDL increased the phosphorylation of FAK in macrophage, while T4 concentration-dependently reversed the effect. These results suggest that T4 modulates macrophage proliferation, migration, senescence, and secretion of inflammation factors in a concentration-dependent way.

A dyslipidemia animal model induced by poloxamer 407 in golden hamsters and pilot study on the mechanism / 药学学报

The aim of this study is to establish a simple and stable model like poloxamer 407 (P-407)-induced dyslipidemia of golden hamster model, and investigate the mechanism of lipid metabolism disturbance in this model. PPARalpha agonist and HMG-CoA reductase inhibitor were administrated to validate the efficacy on regulating lipid metabolism in the dyslipidemia golden hamster model. Six weeks male golden hamsters were chosen to inject P-407 intraperitoneally at a bolus dose of 300 mg x kg(-1), an intermittent injection at a dose of 200 mg x kg(-1) every 72 hours after the bolus. The results showed that P-407-induced golden hamster model characterized as increased serum triglyceride (TG), total cholesterol (TC), free cholesterol (free-CHO), cholesteryl ester (CE), free fatty acids (FFA) and apoB levels, and the hyperlipidemia state maintained at a stable level persistently. Meanwhile, augmented malondialdehyde (MDA) and nitric oxide (NO) level was observed. LCAT and SR-B I mRNA levels in liver of model group were down-regulated (expression ratio is 0.426; 0.783), while HMG-CoA reductase mRNA level was up-regulated (expression ratio is 1.493) compared with those of the normal group. The serum cholesterol and triglyceride levels were significantly lower in P-407-induced dyslipidemia hamster model after treated with atorvastatin (Ato) at a dose of 50 mg x kg(1) or fenofibrate (Fen) at 100 mg x kg(-1) for two weeks. These findings suggest that serum lipid distribution in dyslipidemia golden hamster is similar to that of human, and which may be relevant to the disturbance of the enzymes expression involved in lipid metabolism in liver. Results obtained from this study support the concept that dyslipidemia golden hamster may be an adequate animal model to evaluate the efficacy of lipid-lowering agents.