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1.
Environ Mol Mutagen ; 61(3): 355-360, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31899575

RESUMO

To provide a more comprehensive understanding of genotoxic effects from benzene exposure, its effects on induction of mitochondrial DNA copy number (MtDNAcn) and of micronucleus (MN) were investigated using peripheral blood from workers in China. Changes in mtDNAcn and MN were determined using quantitative real-time polymerase chain reaction (PCR) and cytokinesis-block micronucleus assays (CBMN), respectively, in 58 control and 174 benzene-exposed workers in Shanghai, China. Among the exposed workers, relative mtDNAcn increased and then decreased with increasing doses of benzene exposure. Significant and dose-dependent increase in MN frequencies were observed among the different exposure groups. In addition, the relative mtDNAcn were significantly associated with the MN frequencies in the low-level exposure group (P = 0.046), but not in the high dose groups. Therefore, the mechanisms for induction of MtDNAcn and MN by benzene may be similar from exposure to low doses but different from high doses. Similar increase of MN frequencies and MtDNAcn may be due to oxidative stress induced by benzene at low concentrations, while higher concentrations may start to initiate the cell death pathway. The pathway may be associated with excessive MtDNAcn which can initiate apoptosis while MN can continue to be induced. However, the differential mechanisms need to be investigated because they may represent different levels of risk for different health consequences. On the other hand, our data indicate that induction of MtDNAcn may be a sensitive genotoxic biomarker for workers with exposure to low dose of benzene. Environ. Mol. Mutagen. 61:355-360, 2020. © 2020 Wiley Periodicals, Inc.

2.
Environ Res ; 183: 109156, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-32000003

RESUMO

The selective degradation of recalcitrant antibiotics into byproducts with low toxicity and high biodegradability has been increasingly popular using peroxymonosulfate (PMS) based advanced oxidation processes (AOPs). In this paper, two Fe-based heterogeneous catalysts, bentonite supported Fe-Ni composite (BNF) and biochar-supported Fe composite (Fe/C), were tailored and comprehensively characterized for distinctive physicochemical properties, crystalline structures, and interfacial behaviors. Two widely used antibiotics, sulfapyridine (SPY) and oxytetracycline (OTCs) at their common concentrations in pharmaceutical wastewaters (250 and 10 mg L-1) were tested for degradation in three PMS-based oxidation processes, i.e., PMS, PMS-BNF, and PMS-Fe/C, respectively. Results demonstrated that a large amount of PMS (10 and 1 mM) could effectively remove SPY (0.385 min-1, 100% removal) and OTC (2.737 min-1, 100% removal) via1O2 derived from PMS self-decomposition and non-radical pathway, respectively. Additional Fe-based catalysts (0.5 g L-1 Fe/C and BNF) significantly reduced the PMS consumption (1 and 0.25 mM) and accelerated the reaction rate (1.08 and 5.05 min-1) of SPY and OTC removal. Moreover, the supplementary catalysts shifted the degradation route. The biochar matrix in Fe/C composite contributed to predominant interaction with PMS forming 1O2, which preferably attacked SPY via hydroxylation. In contrast, the redox-active Fe-Ni pairs induced SO4- formation, which could selectively degrade OTC through decarboxylation. Thus, these results are conducive to tailoring advanced yet low-cost heterogeneous catalysts for eco-friendly treatment of antibiotics-rich industrial wastewaters.

3.
J Hazard Mater ; 383: 121240, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-31563767

RESUMO

High-efficiency and cost-effective catalysts are critical to completely mineralization of organic contaminants for in-situ groundwater remediation via advanced oxidation processes (AOPs). The engineered biochar is a promising method for waste biomass utilization and sustainable remediation. This study engineers maize stalk (S)- and maize cob (C)-derived biochars (i.e., SB300, SB600, CB300, and CB600, respectively) with oxygen-containing functional groups as a carbon-based support for nanoscale zero-valent iron (nZVI). Morphological and physiochemical characterization showed that nZVI could be impregnated within the framework of the synthesized Fe-CB600 composite, which exhibited the largest surface area, pore volume, iron loading capacity, and Fe0 proportion. Superior degradation efficiency (100% removal in 20 min) of trichloroethylene (TCE, 0.1 mM) and fast pseudo-first-order kinetics (kobs =22.0 h-1) were achieved via peroxymonosulfate (PMS, 5 mM) activation by the Fe-CB600 (1 g L-1) under groundwater condition (bicarbonate buffer solution at pH = 8.2). Superoxide radical and singlet oxygen mediated by Fe0 and oxygen-containing group (i.e., CO) were demonstrated as the major reactive oxygen species (ROSs) responsible for TCE dechlorination. The effectiveness and mechanism of the Fe/C composites for rectifying organic-contaminated groundwater were depicted in this study.

4.
Nanomicro Lett ; 8(2): 151-156, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-30460275

RESUMO

In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by self-assembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam) (PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam) (PNVCL-COOH) chains onto N-phthaloylchitosan (PHCS) backbone. 1H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and pH presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.

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