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Li Fry posted an update 6 months, 3 weeks ago
Herein, the potential of bimetallic MOFs in catalytic ozonation was investigated for the first time. Three novel ozonation catalysts, i.e. cobalt-based, nickel-based and cobalt/nickel-based metal-organic frameworks (Co-MOF, Ni-MOF and Co/Ni-MOF), were synthesized, characterized by XRD, SEM, N2 sorption-desorption isotherms, FTIR and XPS, and applied in catalytic ozonation for atrazine removal. It was found that the catalysts showed outstanding performance in the catalytic ozonation, especially Co/Ni-MOF which was attributed to multiple metal sites, higher coordination unsaturation, metal centers with larger electron density, and better efficiency in electron transfer than its single-metal counterparts. Under specific experimental conditions, 47.8%, 67.0%, 75.5%, and 93.9% of atrazine were removed after adsorption and degradation in the ozonation system without catalyst, and the catalytic ozonation systems with Co-MOF, Ni-MOF and Co/Ni-MOF, respectively. Higher removal rates could be achieved by growing initial pH, increasing oxidant dosage and reducing pollutant concentration, while an excess of Co/Ni-MOF was not favorable for the catalytic ozonation. Surface hydroxyl groups and acid sites were considered as the critical catalytic sites on Co/Ni-MOF. From the results of EPR tests, O2·-, 1O2 and ·OH were ascertained as the main reactive species in the degradation. It was suspected that O2·- and H2O2 played important roles in the formation of ·OH and the cycle of Co(II)/Co(III) and Ni(II)/Ni(III). Additionally, Co/Ni-MOF displayed good stability and reusability in cycling experiments, ascribed to the enhancement of the porosity and pore hydrophobicity. Finally, based on MS/MS analysis at different reaction times, major degradation pathways for atrazine were proposed.To understand the biofilm formation of biofilm-based processes in wastewater treatment plants (WWTPs), the interaction mechanisms between extracted extracellular polymeric substances (EPS) and three model carrier surfaces (i.e., negatively charged hydrophilic silica, positively charged hydrophilic alumina, and neutral charged hydrophobic polystyrene) were investigated employing a laboratory quartz crystal microbalance with dissipation monitoring equipment (QCM-D) and an atomic force microscope (AFM). The data suggested that surface charge and hydrophobicity of both EPS and carriers played significant roles in the interaction behaviors. Moreover, increases in ionic strength could lead to the increasing zeta potential and hydrophobicity of EPS. It is worth noting that long-range DLVO forces dominated the EPS deposition on carriers in lower ionic strength while short-range Lewis acid-base (AB) interaction controlled the adhesion behaviors in higher ionic strength. Besides, the presence of calcium ions contributed to the adhesion behaviors because of strong charge neutralization and hydrophobic effect. Bound EPS (BEPS) showed higher affinity to model carriers than dissolved EPS (DEPS), which conformed to XDLVO prediction rather than classical DLVO model. Overall, these results provide insights into the influence mechanisms of carrier characteristics, ionic strength, calcium ion and EPS components on the interaction between EPS and representative carriers, contributing to predict and regulate biofilm formation in biofilm-based processes.Heme oxygenase-1(HO-1) is a stress-inducible enzyme that mediates antioxidative and cytoprotective effects to maintain cellular redox homeostasis. In the present study, the full sequence of HO-1 was cloned from golden pompano(Trachinotus ovatus) by RT-PCR and RACE-PCR. The full cDNA sequence of HO-1 was 1349 bp in length which comprised of a 726 bp open reading frame (ORF) preceded by 262 bp 5′-untranslated region (UTR), and followed by a 360 bp 3’UTR, encoding 241 amino acid residues. Phylogenetic analysis revealed that HO-1 showed highest similarity to that of Takifugu rubripes. Tissue distribution analysis showed that the expression level of HO-1 was relatively high in heart, liver and spleen. A trial was conducted to investigate the response of Nrf2/HO-1 signaling pathway to oxidative stress induced by copper. The results showed that mRNA expression of NF-E2-related nuclear factor2 (Nrf2), Kelch-like-ECH-associated protein1 (keap1), superoxide dismutase (SOD), catalase (CAT), HO-1, NAD(P)H quinone oxidoreductase 1 (NQO1) and Glutathione peroxidase (GSH-PX) all significantly increased in copper treated group than that in the control group. This work provides new insight into the molecular mechanism underlying the Nrf2/HO-1 pathway in oxidative response in T. ovatus.Zeranol is an approved but controversial growth-promoting agent for livestock in North America. It is a mycotoxin metabolite secreted by the Fusarium family fungi. The regulatory bodies in this region have established the acceptable daily intake and exposure below the level would not significantly increase the health risk for humans. However, their European counterparts have yet to establish an acceptable level and do not permit the use of this agent in farm animals. Given the growth-promoting ability of zeranol, its effect on energy metabolism was investigated in the current study. Our results indicated that zeranol could induce glucose transporter type 4 (GLUT4) expression in 3T3 L1 cells at 10 μM and initiate the translocation of the glucose transporter to the membrane as assayed by confocal microscopy. The translocation was likely triggered by the increase of GLUT4 and p-Akt. check details The insulin signal transduction pathway of glucose translocation was analyzed by Western blot analysis. Since no increase in the phosphorylated insulin receptor substrate in zeranol-treated cells was evidenced, the increased p-Akt and GLUT4 amount should be the mechanism dictating the GLUT4 translocation. In summary, this study showed that zeranol could perturb glucose metabolism in differentiated 3T3 L1 adipocytes. Determining the growth-promoting mechanism is crucial to uncover an accepted alternative to the general public.The photolysis dynamics of m-fluorophenol (m-FPhOH) and o-fluorophenol (o-FPhOH) have been investigated with time-resolved velocity map imaging (TR-VMI) and time-resolved ion-yield (TR-IY) techniques. Following excitation to the origin of S1 (ππ∗) state of m- and o-FPhOH, H atoms elimination mediated by tunneling through the potential barrier under the S1 (ππ∗)/S2 (πσ∗) conical intersection (CI) has been observed as a Gaussian feature signal centered at a total kinetic energy release (TKER) of ∼6000 cm-1 for both molecules. The quantum tunneling mechanism has been identified as the main decay pathway of S1 state for m-FPhOH, and the tunneling lifetime of 2.1 ns has been obtained from the TR-VMI measurements of H fragments. This tunneling mechanism is further confirmed by the studies on the selective O-H deuterated species, m-FPhOD, and consolidated by our theoretical calculations. However, the photolysis dynamics is quite different for the photoexcited o-FPhOH. The much lower yield of the H atoms originating from tunneling hinders the extraction of a reliable tunneling lifetime for o-FPhOH.
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