大气细颗粒物引发的神经毒性和分子机理

大气细颗粒物(Atmospheric fine particulate matters,PMs)对人体健康产生的潜在危害已得到广泛关注.越来越多的研究表明,PMs暴露可产生呼吸、心血管系统等损伤影响,然而PMs是否可以进入大脑并产生神经毒性,一直是近年来大气雾霾健康效应的重要研究方向.本文通过梳理现有流行病学研究证据以...     

Newly designed polysiloxane-graft-poly (oxyethylene) copolymeric surfactants: preparation,surface activity and emulsification properties

Two sets of comb-grafted polymeric surfactants based on poly-(methylhydrogen siloxane) (PHMS) and/or poly(dimethylsiloxane) (PHMS-PDMS) were prepared by sililation of the active Si-H group with an active omega-vinyl group of specially designed undecenoic-polyethyleneglycol esters (UPEG) to form newly-designed polysiloxane-grafted-polyethyleneglycol comb-copolymeric surfactants.The hydrophilic moieties are hooked to the hydrophobic backbone through a spacer (undecenoic acid). The variations in the surfactants' structures were in the length and density of the grafted hydrophilic moieties, the chain length (DP) and nature of the hydrophobic backbone.The first 12 different polymeric surfactants (set 1), termed PHMS-UPEG, were found to be ineffective emulsifiers with limited ability to stabilize oil-in-water emulsions. The second set of surfactants, named PHMS-PDMS-UPEG comb-grafted copolymers, significantly reduced the oil-water interfacial tension and effectively stabilized several types of oil-in-water emulsions. The best emulsifier of this set (PHMS-PDMS-52-UPEG-45), seems to be the one whose anchor backbone (PHMS-PDMS) dissolves (rather than spreads) in the oil phase, and whose stabilizing moieties are sufficiently long (45 EO units) and hooked to the silicone backbone at high density (52% substitution).     

Trace analysis of polycyclic aromatic hydrocarbons in suspended particulate matter by accelerated solvent extraction followed by gas chromatography–mass spectrometry

An analytical procedure based on extraction by accelerated solvent extraction (ASE) followed by gas chromatography–mass spectrometry (GC/MS) analysis has been developed for the determination of particulate polycyclic aromatic hydrocarbons (PAHs) from large-volume water samples (20 L). The effect of temperature and number of cycles on the efficiency of ASE was investigated: the best results were obtained by using a temperature of 100°C and one static cycle. A mixture of hexane/acetone 1:1 (v/v) was used as extraction solvent. Mean total method recovery under optimized conditions was 85%. The developed methodology was applied to the analysis of suspended particulate matter from Lake Maggiore waters (north of Italy). Mean PAH concentrations in suspended particulate matter from Lake Maggiore ranged from 0.2 ng L⁻¹ for anthracene to 18.7 ng L⁻¹ for naphthalene.     

Effect of Chemical Treatment on TiO2 Particles by IMPS

The photodegradation reaction rate of CHCl3 in TiO2 particulate suspension was imperoved significantly by HCl-treatment.The effect of HCl-treatment on the photocatalytic activity of TiO2 was strdied in a PEC cell by using Intensity-Modulated Photocurrent Spectroscopy(IMPS).The magntude of photocurrent response and the characteristic frequencies of the upper and lower semicircles in the complex plane of IMPS response were analyzed,and the ccathodic and anodic reaction processes of photogenerated holes and electrons were discussed.The increases in the cathodic and anodic photocurrent response and in the time constants of both cathodic and anodic reaction processes of photogenerated holes and electrons were discussed.The increases in the cathodic and anodic photocurrent response and in the time constants of both cathodic and anodic reaction processes indicate that HCl-treatment leads to the improvement of the photocatalytic activity of TiO2 and a change of the photocatalytic kinetic mechanism.     

微粒溶胶凝胶法合成锂离子电池用正极材料LiNi0.85Co0.15O2及表征

以LiOH·H₂O、Ni(CH₃COO)₂·4H₂O 和 Co(CH₃COO)₂·4H₂O为原料，在水-乙醇体系中，采用微粒溶胶凝胶方法(PSG)成功地制备了锂离子电池用正极材料LiNi_0.85Co_0.15O₂。使用差热-热重(DTA-TG)方法来研究凝胶的热分解过程。粉末X-射线衍射(XRD)测试表明，在700 ℃、氧气氛中，原料混合物能形成具有较好α-NaFeO₂层状结构的晶型化合物。扫描电镜(SEM)显示，与固相合成方法相比，PSG制备的LiNi_0.85Co_0.15O₂颗粒较细、且颗粒大小分布均匀。充放电实验结果表明，PSG合成的LiNi_0.85Co_0.15O₂首次放电容量为196.4 mAh/g, 10次循环之后，容量还有189.1 mAh/g (3.0～4.3V、18 mA/g)，显示其具有良好的循环性能；而同样条件下，固相法合成的样品，首次放电容量为187.3 mAh/g，10次循环之后，容量衰减为167.1 mAh/g。     

Role of iron and copper in particulate methane monooxygenase of Methylosinus trichosporium OB3b

The role of iron and copper in particulate methane monooxygenase (pMMO) of Methylosinus trichosporium OB3b is described, and an overview of the enzyme's properties is presented. The pMMO from M. trichosporium OB3b was solubilized in the detergent n-dodecyl--D-maltoside and purified by chromatographic techniques. The enzyme consists of 0.9 iron atoms and 12.8 copper atoms per molecule. The iron site in pMMO may be mononuclear non-heme iron. Copper exists as either copper ion coupled to four nitrogen atoms and/or trinuclear copper cluster wherein copper ions are ferromagnetically coupled.     

Coalescence in crude oil emulsions investigated by a light transmission method

Using a strong light source and a sensitive detector the light transmission of crude oil emulsions can be measured. A semi-empirical theory describes how the measured optical density results from the interaction of absorption and scattering. Changes in the scattering can be used to investigate the coalescence effects caused by demulsifiers. The method is of use in testing demulsifier effectiveness.     

Determination of Polycyclic Aromatic Hydrocarbons in Biodiesel Exhaust from Jatropha curcas and Chlorella variabilis by Gas Chromatography with Flame Ionization Detection

Biodiesel serves as a promising alternative to the conventional petroleum fuels and is considered to be a renewable source of energy which can be used in compression-ignition engines with minimum or no modifications. Two biodiesels derived from Jatropha curcas seeds and marine microalga Chlorella variabilis were substituted for petrodiesel and 16 priority polycyclic aromatic hydrocarbons (United States Environmental Protection Agency) were targeted for quantification through gas chromatography equipped with a flame ionization detector. For comparison, petrodiesel was selected as a control, and the analyte concentrations were calculated through calibration curves with correlation coefficient ranging from 0.9909 to 0.9999. The analytical figures of merit were determined for each analyte. The relative standard deviations for intra-day repeatability and inter-day reproducibility were in the range of 4.47–8.75%. The results indicated a significant decrease of around 77 and 68% in the overall polycyclic aromatic hydrocarbon concentrations in the particulate matter originating from J. curcas and microalga C. variabilis biodiesel, respectively. This study is perceived as an important step toward describing the green emission behavior of these biodiesels and their merits compared to the conventional petroleum-based fuels.     

A new approach for the determination of sulphur in airborne particles by HR-CS ETAAS

In this work, water and nitric acid extractable sulphur concentrations in PM2.5 fraction of urban aerosols were determined by high-resolution continuum source electrothermal molecular absorption spectrometry using most suitable CS molecular absorption band at 258.056 nm. For this purpose, the PM2.5 airborne particulates were collected on quartz filters using a high-volume sampler (500 L/min) in Istanbul (Turkey) during six months (January–June) of two consecutive years. The instrumental and experimental parameters (pyrolysis temperature, molecule formation temperature and leaching reagents) were optimised. The validity of the method for the sulphur was tested using standard reference material and the results were found to be in the uncertainty limits of the certified value.