Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with a matrix of carbon nanotubes for the analysis of low-mass compounds in environmental samples

The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for environmental analysis has been mainlyfocused on qualitative analysis of high-mass molecules, such as toxins, humic acid, and microorganisms. Herein,we describe a novel MALDI-TOF-MS method with a matrix of oxidized carbon nanotubes for analysis of low-mass compounds in environmental samples. A number of chemicals in the environment were qualitatively analyzed by the present method, and it was found that most of them, especiallythe highly polar chemicals, were measurable with high sensitivity. With the intrinsic ability to measure high-mass chemicals, this method can compensate for the current shortage of methods for environmental analysis for the measurement of highly polar or high-mass chemicals. For sample analysis, arsenic speciation in Chinese traditional medicines was qualified and diphenylolpropane in water samples was quantified. With the relatively high tolerance of the method to interfering molecules, a simple pretreatment or even no pretreatment could be employed before MS detection. Furthermore, this method can be employed in a high-throughput format.     

The role of silver species on Ag/Al2O3 catalysts for the selective catalytic oxidation of ammonia to nitrogen

The role of Ag species on Ag/Al₂O₃ catalyst for the selective catalytic oxidation (SCO) of NH₃ to N₂ was studied using 10 wt% Ag/Al₂O₃ catalysts prepared with impregnation, incipient wetness impregnation and sol–gel methods. The catalyst characterization was preformed using N₂ adsorption–desorption, UV/Vis, TEM and XRD. O₂-chemisorption and H₂–O₂ titration were measured to confirm the metal dispersion on the catalyst. The Ag species state and Ag particle size have significant influence on the Ag/Al₂O₃ activity and N₂ selectivity of the SCO of NH₃ at low temperature. Ag⁰ is proposed to be an active species on the H₂ pretreated catalyst at low temperature (<140 °C). It is evident that well-dispersed and small particle Ag⁰ enhances catalytic activity at low temperature, whereas large particle Ag⁰ is relate to a high N₂ selectivity. In contrast, Ag⁺ could also be the active species at temperatures above 140 °C.     

Fe-mordenite/cordierite monolith for the catalytic decomposition of nitrous oxide

Mordenite zeolites were coated on cordierite support by in situ hydrothermal method or dip-coating method. The mordenite/cordierite was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques and their stability was studied. The mordenite/cordierite monolith prepared by in situ synthesis showed much better stability than that prepared by dip-coating. Iron was introduced into mordenite/cordierite by ion exchange and Fe-mordenite/cordierite catalyst was prepared. Fe-mordenite/cordierite prepared from in situ synthesis exhibited good activity and stability for N₂O catalytic decomposition, with great potential for future application.     

Arsenic removal through adsorption, sand filtration and ultrafiltration: In situ precipitated ferric and manganese binary oxides as adsorbents

This study proposes a process consisting of in situ precipitated ferric and manganese binary oxides (FMBO) adsorption, sand filtration, and ultra-filtration (UF) for arsenic removal. Bench scale studies indicate that the FMBO shows higher capability of removing arsenic than hydrous ferric precipitate (HFO) and hydrous manganese oxide (HMO). This is ascribed to the combined effects of oxidizing As(III) and adsorbing As(V) for FMBO. The continuous experiments indicate that this process is effective for arsenic removal. In the presence of 0.624 mg/L As(III), when the Fe(II) dosage is 3 mg/L and the KMnO₄ dosage is equivalent to the sum of As(III) and Fe(II), the residual As concentration is as low as 29.2 μg/L. The adsorption of arsenic onto FMBO is fast, and the hydraulic retention time (HRT) of 45 s is enough for the adsorption unit. Sand filtration leads to more than 90% of arsenic removal, and UF further removes the particulate arsenic that passes through the sand filter. During the backwashing of the sand filter, the maximal aqueous arsenic concentration is 0.105 mg/L (at 150 s), and the dissolution of arsenic from FMBO is neglectable. The main operating cost of this process is as low as 0.355 RMB/m³, which is acceptable in rural areas for arsenic removal in engineering.     

PBBs, PBDEs, and PCBs in foods collected from e-waste disassembly sites and daily intake by local residents

This study was conducted to estimate the total daily dietary intakes (TDIs) of three PHAHs subfamilies for residents living around the large e-waste disassembly sites in the Zhejiang province of China. A total of 191 food samples (including seven food groups and drinking water) were obtained from the disassembly sites and the control site in April, 2007. The levels of three PHAHs were measured by GC-MS. The estimated TDIs of PBBs (385.5 ng day^− 1), PBDEs (195.9 ng day^− 1), and PCBs (12,372.9 ng day^− 1) in the disassembly sites were approximately 2-3 times higher than those in the control site, which suggested that these PHAHs from e-waste might have entered into the food chain. Rice appeared to be the food group showing the highest contribution to the individual dietary intakes of these PHAHs. The estimated TDIs were also compared with those results reported recently in the literature and their respective reference doses by WHO (or Health Canada). By and large, although the estimated TDIs for the PHAHs under study were lower than their respective reference doses, they were obviously higher than those observed in other places listed in the literature, thus suggesting that residents living around the disassembly sites have been exposed to higher levels of PHAHs than those places, and might thus be at greater health risk.     

Burdens of PBBs, PBDEs, and PCBs in tissues of the cancer patients in the e-waste disassembly sites in Zhejiang, China

This study was conducted to explore the burdens of PBBs, PBDEs, and PCBs among cancer patients living in the e-waste disassembly sites. The contents of 23 PBB congeners, 12 PBDE congeners, and 27 PCB congeners in kidney, liver, and lung samples were measured by GC-MS. The results showed that low-brominated PBBs and PBB153 were the predominant congeners. PBDE47 were the most predominant PBDE congeners. PBDE209 were detected in > 70% of the samples, with geometric means ranging from 64.2 to 113.9 ng g^− 1 lipid. Among the three subfamilies of PHAHs, PCB concentrations were the highest. The detected levels of PHAHs were in the same order of magnitude in the three tissues, which indicated that any of the three tissues could be the suitable indicator for assessing body burdens of PHAHs. PBB contents (181-192 ng g^− 1 lipid) were obviously higher than those reported in the general USA population (3-8 ng g^− 1 lipid). PBDE levels (174.1-182.3 ng g^− 1 lipid) were comparable to those reported in the USA population, but significantly higher than those of the European population. PCBs levels were comparable to those of the European population. The high cancer incidence in the disassembly sites may be related to higher burdens of PBBs, PBDEs, and PCBs in tissues.     

铝的水溶液化学特征及其聚合物生成机制

聚合氯化铝（PACl）是水处理中应用较广泛的絮凝剂。研究表明,PACl中各种铝聚合物的含量直接影响其絮凝效率。本文综述铝的水解聚合特性以及制备絮凝剂过程中的铝聚合物生成机制,着重介绍了Al13聚合物的结构特性、生成机制以及制备过程中各种因素的影响,为Al13絮凝剂的进一步研究奠定了基础。     

Flow insensitive points-to sets

Pointer analysis is an important part of source code analysis. Many programs that manipulate source code take points-to sets as part of their input. Points-to related data collected from 27 mid-sized C programs (ranging in size from 1168 to 87,579 lines of code) is presented. The data shows the relative sizes and the complexities of computing points-to sets. Such data is useful in improving algorithms for the computation of points-to sets as well as algorithms that make use of this information in other operations.     

Impacts of anions on the electrochemical oxygen reduction reaction activity and stability of Pt/C in alkaline electrolyte

Pt is the benchmark oxygen reduction reaction (ORR) catalyst for the anion exchange membrane fuel cells. In this paper, we have done systematic studies on the influence of anions (F⁻, Cl⁻, Br⁻, I⁻, CO₃²⁻, SO₄²⁻, SO₃²⁻ and S²⁻) to the ORR activity and durability of Pt/C in alkaline condition. It was found that the anions have less impact to Pt/C in alkaline than in acid. I⁻, SO₃²⁻, and S²⁻ have the poisoning effect and the other anions do not influence the ORR activity significantly. In the accelerating durability test, SO₃²⁻ and S²⁻ promote the degradation of the Pt/C catalysts. It was found that the impacts of anions are relative to the standard reduction potential of the anions. The anions with low potential have poisoning impact to the activity and durability of Pt/C. This study provides fundamental understandings of the impacts of anions on Pt/C, which may give insights in design of anion exchange membrane fuel cells.     

Flower-like MOF-derived Co–N-doped carbon composite with remarkable activity and durability for electrochemical hydrogen evolution reaction

Electrochemical hydrogen evolution reaction (HER) is one of the most economical, sustainable, and attractive methods to produce hydrogen. Contemporarily, it is still a challenge to develop low-cost catalysts with high activity and durability for HER. Herein, we report a simple strategy to develop a Co–N-doped carbon electrocatalyst derived from a new cobalt metal-organic framework (MOF). The new flower-like 2D→3D MOF {[Co(BIPA)(5-OH-bdc)](DMF)}_n (1) was constructed based on bis(4-(1H-imidazol-1-yl)phenyl)amine (BIPA) and 5-hydroxyisophthalic acid (5-OH-H₂bdc). After that, the Co–N-doped carbon composite Co-MOF-800 was prepared via calcination of MOF 1. Interestingly, Co-MOF-800 exhibited excellent electrocatalytic activity and durability for HER. The onset potential (0.12 V) and E_j=10 value (0.193 V) of the Co-MOF-800 electrode were comparable to that of the most active non-precious metal HER electrocatalysts derived from other MOFs. The HER performance of Co-MOF-800 was stable without degradation even after long-term cycling.