摘要：
Reduced graphene oxide (rGO)/WO3 nanoplates composites were synthesized via a facile one-pot hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption spectra (DRS), fourier transform infrared spectroscopy (FTIR) and photoluminescence spectra (PL). The photocatalytic degradation of methylene blue (MB) by the rGO/WO3 composites was investigated and optimized, suggesting the optimal amount of rGO in the composite was 15 wt%. The significantly enhanced photocatalytic activity of rGO/WO3 composites could be attributed to the excellent accepting and transporting electrons properties of rGO.
摘要：
Heterocyclic aromatic amines (HAAs) are carcinogens formed during the cooking of meats or arise in tobacco smoke. The genotoxic N-oxidized metabolites of HAAs bind to Cys residues of proteins to form arylsulfinamide adducts. However, these adducts are unstable and undergo hydrolysis during enzymatic digestion, and thus have been precluded as biomarkers of exposure to HAAs. Arylsulfinamide adducts of HAAs can undergo oxidation to form stable arylsulfonamide linkages, which are chemically stable and amenable for analysis. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogen present in cooked meat. We established a quantitative MS-based method to measure the sulfinamide adduct of PhIP formed at the cysteine(34) (Cys(34)) residue of human serum albumin (SA), following chemical oxidation of PhIP-moclified SA with m-chloroperoxybenzoic acid. Different enzyme systems (trypsin; chymotrypsin; trypsin/chymotrypsin; proteinase K; pronase E; and pronase E/leucine aminopeptidase/prolidase) were evaluated for their proficiency of digestion of SA modified with PhIP. The strongest signal was observed for the L(31)QQC*PFEDHVIC41 peptide, by ultraperformance liquid chromatography and ion trap MS. A limit of quantification value was 0.3 fmol of LQQC*PFEDHVK per mu g SA, or 2.5 adducts per 10(5) SA molecules, when assaying 0.75 mu g of SA. Biological significance This article describes a mass spectrometric based method to characterize and measure human serum albumin (SA) adducts of 2-amino-1-methyl-6-phenylimidazo[4,5-11pyridine (PhIP), a carcinogenic heterocyclic aromatic amine formed in cooked meats and tobacco smoke. PhIP undergoes metabolic activation to form reactive N-oxidized intermediates that bind to DNA and proteins. N-oxidized PhIP metabolites bind to the Cys' residue of SA to form a sulfinamide linkage. However, the linkage undergoes hydrolysis during proteolysis, precluding the employment of this adduct as a biomarker in human studies. We have shown that the sulfinamide linkage undergoes oxidation to form the [cysteine-S-yl-PhIP]-S-dioxide, a sulfonamide linked adduct which is stable toward proteolysis. The specificity and efficiency of several different proteases toward the digestion of the SA-Cysm-PhIP adduct were examined. The combination of trypsin and chymotrypsin produced the single-missed cleaved peptide LQQC*PFEDHVK in high yield. Moreover, denaturation and chemical reduction of the internal Cys disulfide bonds of SA were not required for the recovery of LQQC*PFEDHVIC The novel chemistry and proteomic approaches developed in this study may be applied to monitor biologically reactive N-oxidized intermediates of arylamines through their adduction products formed at nucleophilic Cys residues of proteins. (C) 2014 Elsevier B.V. All rights reserved.
摘要：
A series of hierarchical mesoporous ZSM-5 zeolites with different morphology were successfully synthesized by the CO2-in-water microemulsion method, and mesoporosity was formed without organotemplate. The different synthesis conditions, including silica alumina molar ratio, stirring time and compressed CO2 pressure, were systematically investigated to discuss the influence of these conditions on the morphology of ZSM-5 zeolite. The resulting samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP) and nitrogen adsorption-desorption measurement. XRD results indicated that compressed CO2 route for the synthesis of MFI zeolites had a fast crystallization rate and good crystallinity. SEM images showed that the ZSM-5 hierarchical mesoporous ZSM-5 zeolite had a uniform chain-like crystal morphology, whereas silicalite-1 displayed a monodisperse crystal morphology. In addition, the nitrogen adsorption-desorption measurement provided sufficient evidence for the presence of hierarchical mesopores in ZSM-5 zeolite.
摘要：
Effect and benefits of a product or service could be analyzed and evaluated by life cycle assessment during the whole life cycle. Urban sewage treatment plants could improve and control urban water pollution escalating, but it also had certain harm to environment. Effect and benefits of urban wastewater treatment plant A and B were analyzed and evaluated, 13 factors were selected, and comprehensive benefits were researched quantificationally using the method of analytic hierarchy process. It found that urban wastewater treatment plant A who applied A/O process had better benefits than urban wastewater treatment plant B who applied BIOLAK process.
摘要：
In this paper, the use of titanium dioxide nanotubes (TDNTs) as solid-phase extraction adsorbent for on-line microcolumn separation and preconcentration of trace metals (Mn, Co, Cr, Zn, and Pb) was investigated by inductively coupled plasma mass spectrometry (ICP-MS). The effects of the experimental parameters, including pH, sample flow rate and volume, elution conditions and interfering ions on the recoveries of the analytes were investigated systematically. The experimental results showed that the analytes were adsorbed quantitatively on TDNTs in the pH range from 7.0 to 9.0 and then eluted completely with 1.5 mol L-1 HNO3 solution. Under the optimum conditions, the detection limits of this method ranged from 0.3 pg mL(-1) (Co) to 15 pg mL(-1) (Zn) with a 150-fold enrichment factor; the relative standard deviations (RSDs) for the analytes were less than 4.5% (n=9, c=1.0 ng mL(-1)). The linear range of the calibration curve spanned three orders of magnitude. This method was applied to the determination of trace elements (Mn, Co, Cr, Zn, and Pb) in natural water samples with recoveries of 94.8-104%. In order to validate this method, the certified reference material GBW 07601 Human Hair was analyzed, and the determined values were in good agreement with the certified values.
摘要：
In this paper, an in situ matrix separation method has been developed for the determination of trace rare earth impurities in high purity tantalum pentaoxide (Ta 2 O 5 ) by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). A polytetrafluoroethylene (PTFE) slurry was used as a chemical modifier to convert both the matrix (Ta) and the rare earth elements (REEs) into their fluorides, with different volatilities, at high temperature in a graphite furnace. The more volatile TaF 5 was removed in situ by selective vaporization prior to the determination of the analytes, eliminating matrix effects. Under optimum operating conditions, the detection limits (DLs) for La, Eu, and Yb were found to be 4.2, 1.9, and 3.5 ng g-1, with relative standard deviations (RSDs) less than 5.0%. The recommended method was successfully applied to the determination of trace impurities (La, Eu, and Yb) in Ta 2 O 5 , and the results were in good agreement with those obtained by pneumatic nebulization (PN) ICP-MS after separation of the matrix using a solvent extraction procedure.
摘要：
A microcolumn preconcentration method coupled to inductively coupled plasma mass spectrometry (ICP-MS) was developed for the preconcentration and determination of trace rare earth elements (REE s ) in environmental water samples, based on titanium dioxide nanotubes (TDNTs) as a solid phase extraction adsorbent. The experimental parameters for the preconcentration of REE s , such as pH, sample flow rate and volume, eluent concentration and interfering ions on the preconcentration of REE s , were examined systematically. Under the optimum conditions, the detection limits for Nd, Tb, and Ho were found to be 0.093, 0.018, and 0.025 pg mL 1 , respectively, with a 100-fold enrichment factor. The relative standard deviations (RSD s ) were less than 4.6% (n=9, c=1.0 ng mL'1). The proposed method was applied to the determination of trace rare earth elements (Nd, Tb, and Ho) in real samples with satisfactory results. The recoveries were between 93.5% and 104%.
