壳聚糖-沸石杂化膜的制备及其对甲基橙的吸附

采用物理共混法制备了壳聚糖-沸石杂化膜,用扫描电镜(SEM)和热重分析仪(TGA)对其进行表征,并系统地研究了壳聚糖-沸石杂化膜对甲基橙的吸附行为。结果表明,最佳质量配比为(沸石/壳聚糖)为1∶20;pH值对吸附的影响最为关键,在实验浓度的范围内对甲基橙溶液最大吸附量为974.05 mg/g。杂化膜对甲基橙的等温吸附行为符合Lang-muir模型,吸附动力学模式符合准二级动力学方程,考虑以化学吸附行为为主。杂化膜有良好的再生能力。     

非均相Fenton和非均相US-Fenton体系中甲基橙降解动力学

在初始pH=3的条件下研究了甲基橙在非均相Fenton体系和非均相US-Fenton体系中的降解动力学。研究内容包括表观动力学方程和活化能。研究表明,超声的引入可以提高甲基橙的降解效率和降解速率。对比非均相Fenton和非均相US-Fenton体系中的表观动力学方程表明超声的引入可以提高反应速率常数,此外,还可以提高H2O2的利用率。通过对比分析,超声的引入可以降低反应所需的活化能,在超声的存在下,甲基橙的氧化活化能为25.12 kJ/mol,而在没有超声的条件下,需要的活化能为41.49 kJ/mol。     

Alterations of protein profile in zebrafish liver cells exposed to methyl parathion: a membrane proteomics approach

Methyl parathion (MP) is an extensively used organophosphorus pesticide, which has been associated with a wide spectrum of toxic effects on environmental organisms. The aim of this study is to investigate the alterations of membrane protein profiles in zebrafish liver (ZFL) cell line exposed to MP for 24 h using proteomic approaches. Two-dimensional gel electrophoresis revealed a total of 13 protein spots, whose expression levels were significantly altered by MP. These differential proteins were subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis, and nine proteins were identified to be membrane proteins, among which seven were up-regulated, while two were down-regulated. In addition, the mRNA levels corresponding to these differential membrane proteins were further analyzed by quantitative real-time PCR. And the differential expression of arginase-2 was specially validated via Western blotting. Regarding the physiological functions, these proteins are involved in molecular chaperon, cytoskeleton system, cell metabolism, signal transduction, transport and hormone receptor respectively, suggesting the complexity of MP-mediated toxicity to ZFL cell. These data could provide useful insights for better understanding the hepatotoxic mechanisms of MP and develop novel protein biomarkers for effectively monitoring MP contamination level in aquatic environment.     

黄麻纤维活性炭对亚甲基蓝和甲基橙吸附动力学

以黄麻纤维为原料,采用磷酸活化法制备活性炭。研究黄麻纤维活性炭对亚甲基蓝和甲基橙2种染料的吸附行为。结果表明,采用磷酸制备的活性炭,由于表面含有羧基和含磷官能团等酸性基团,能够促进活性炭对亚甲基蓝的吸附;黄麻纤维活性炭对2种染料的平衡吸附量、初始吸附速率均随着初始浓度的增加而升高;相同条件下,黄麻纤维活性炭对亚甲基蓝的平衡吸附量大于甲基橙;黄麻纤维活性炭对两种染料的吸附行为更符合准二级动力学模型。     

阴极电生H_2O_2及电-Fenton法降解甲基橙

对石墨-PTFE阴极的主要制作参数和在无隔膜系统中电生H2O2的主要工艺参数进行了研究。结果发现,石墨与PTFE的质量比为4∶1~3∶1之间的石墨-PTFE阴极经350℃1 h煅烧后性能最好。采用磁力搅拌代替通常的氧气扩散和空气鼓泡等供氧方法,可简化系统的供氧设备,降低废水的处理成本,更易于放大和实施,且可充分利用阳极电生的氧气。石墨-PTFE阴极有较好的稳定性,重复使用10次之后,电生H2O2的活性没有下降。在由石墨-PTFE阴极和铁阳极组成的电-Fenton系统中对甲基橙溶液进行了降解,脱色效果显著。     

Ciprofloxacin-sensitive and ciprofloxacin-resistant Campylobacter jejuni are equally susceptible to natural orange oil-based antimicrobials

A total of 10 ciprofloxacin-sensitive (ciprofloxacin minimum inhibitory concentration, MIC < 0.5 μ g/ml) and 10 ciprofloxacin-resistant (MIC 16 to 32 μ g/ml) presumptive C. jejuni were further characterized and evaluated for their inhibition by natural orange oil fractions. Partial species identification was performed by using a hippuricase gene-based polymerase chain reaction (PCR) assay. One of the isolates appeared to be atypical and failed to hydrolyze hippurate. Of the ciprofloxacin-resistant C. jejuni isolates tested, six were found to have their quinolone resistance determined by a C → T mutation in codon 86 of gyrA. Both groups of ciprofloxacin-sensitive and –resistant C. jejuni isolates were most susceptible to cold-pressed terpeneless Valencia orange oil (C4) which yielded inhibition zones from 44.0 ± 1.4 to 80 ± 0.0 mm. Less inhibitory responses were recorded for 5-fold concentrated Valencia orange oil (C3) and distilled d-limonene (C7) which exerted similar effects on both ciprofloxacin-sensitive and –resistant C. jejuni isolates. In general, ciprofloxacin-resistant and –sensitive C. jejuni isolates were equally susceptible to the respective orange oil fractions.     

Photocatalytic degradation of an azo dye using N-doped NaTaO3 synthesized by one-step hydrothermal process

N-doped NaTaO₃ compounds (NaTaO_3−xN_x) with nano-cubic morphology were successfully synthesized by one-step hydrothermal method and Methyl Orange (MO) was used as a model dye to evaluate their photocatalytic efficiency under visible-light irradiation. The as-prepared NaTaO_3−xN_x samples were characterized by various techniques, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra and GC-MS. The results indicate that NaTaO_3−xN_x displays a pure perovskite structure when the synthesis temperature is higher than 180 °C. Moreover, as observed by SEM images, the particles of resultant NaTaO_3−xN_x show cubic morphology with the edge length of 200-500 nm, which can be easily removed by filtration after photocatalytic reaction. Doping of N increases the photocatalytic activity of NaTaO₃, and NaTaO_2.953N_0.047 shows the highest visible-light photocatalytic activity for the degradation of MO. Based on the experiment results, a possible mechanism of the photocatalysis over NaTaO_3−xN_x and the photodegradation pathway of MO were proposed.     

Periphyton as a bioindicator of mercury pollution in a temperate torrential river ecosystem

Mercury presents a potential risk to the environment and humans, especially in its methylated form. It is among the highest priority environmental pollutants. River Idrijca (Slovenia) is highly contaminated with mercury due to past mercury mining. The aim of this work was to investigate whether the periphyton community in rivers such as Idrijca is a suitable indicator of Hg pollution and of changes in mercury methylation and could serve as an early warning system of increased input of MeHg in the food chain. Periphyton is the only site of primary production in temperate torrential rivers such as Idrijca and is therefore an important link in the food chain. It is also a potential site of Hg accumulation and its introduction to higher trophic levels. Our aim was to assess the response of the periphyton to seasonal and spatial variations in mercury levels and to evaluate its potential as an early warning system of changes in mercury reactivity and mobilization The results indicate that periphyton in a torrential river is too complex and unpredictable to be used as a sole indicator of mercury concentrations and changes in the river. Nevertheless, it can complement environmental measurements due to its importance in the riverine food web.     

Mercury in Tree Swallow Food, Eggs, Bodies, and Feathers at Acadia National Park, Maine, and an EPA Superfund Site, Ayer, Massachusetts

We monitored nest boxes during 1997–1999 at Acadia National Park, Mt. Desert Island, ME and at an old-field site in Orono, ME to determine mercury (Hg) uptake in tree swallow (Tachycineta bicolor) eggs, tissues, and food boluses. Also, in 1998–1999 we monitored nest boxes at Grove Pond and Plow Shop Pond at a U.S. Environmental Protection Agency Superfund site in Ayer, MA. We recorded breeding success at all locations. On average among locations, total mercury (THg) biomagnified 2 to 4-fold from food to eggs and 9 to 18-fold from food to feathers. These are minimum values because the proportion of transferable methyl mercury (MeHg) of the THg in insects varies (i.e., 35%–95% of THg) in food boluses. THg was highest in food boluses at Aunt Betty Pond at Acadia, whereas THg in eggs was highest at the Superfund site. A few eggs from nests at each of these locations exceeded the threshold (i.e., 800–1,000 ng/g, wet wt.) of embryotoxicity established for Hg. Hatching success was 88.9% to 100% among locations, but five eggs failed to hatch from 4 of the 11 clutches in which an egg exceeded this threshold. MeHg in feathers was highest in tree swallows at Aunt Betty Pond and the concentration of THg in bodies was related to the concentration in feathers. Transfer of an average of 80%–92% of the Hg in bodies to feathers may have enhanced nestling survival. Residues of Hg in tissues of tree swallows in the Northeast seem higher than those of the Midwest.     

铁掺杂纳米二氧化钛溶胶的制备及性能研究

文章采用一种简单的方法于低温条件下制备出掺铁纳米TiO2溶胶。通过在可见光条件下对吖啶橙的光催化降解,对掺铁纳米TiO2溶胶和纳米TiO2溶胶的光催化活性进行了研究比较,结果表明掺铁纳米TiO2溶胶的光催化活性较高,铁的掺杂量为1%时光降解效果较好。