Using crosslinked polyvinyl alcohol polymer membrane as a separator in the microbial fuel cell

Separator between anode and cathode is an essential part of the microbial fuel cell （MFC） and its property could significantly influence the system perfor- mance. In this study we used polyvinyl alcohol （PVA） polymer membrane crosslinked with sulfosuccinic acid （SSA） as a new separator for the MFC. The highest power density of 7594-4 mW-m-2 was obtained when MFC using the PVA membrane crosslinked with 15% of SSA due to its desirable proton conductivity （5.16 x 10-2 S.cml）. The power density significantly increased to 11064- 30 mW.m-2 with a separator-electrode-assembly config- uration, which was comparable with glass fiber （11704- 46 mW.m-2）. The coulombic efficiencies of the MFCs with crosslinked PVA membranes ranged from 36.3% to 45.7% at a fix external resistance of lO00f2. The crosslinked PVA membrane could be a promising alter- native to separator materials for constructing practical MFC system.     

Seasonal and spatial variations of acid-volatile sulphide and simultaneously extracted metals in the Yangtze River Estuary

Surface sediments were collected from the Yangtze River Estuary (YRE) in May 2012, August 2012, November 2012 and February 2013 to analyse the seasonal and spatial distributions of acid-volatile sulphide (AVS), simultaneously extracted metals (SEM) and the sediment toxicity. An optimised method was used for the AVS and SEM analysis and the results showed that the seasonal variations of AVS were positively correlated with changes in water temperature and the position of higher AVS was relatively fixed. The average of SEM was gradually increased from May 2012 to February 2013 and there were abnormally high values of SEM_Cu and SEM_Ni in the YRE. Concentrations of the five SEM components were in the following order: Cd?相似文献   

Denitrification in bottom sediment near oil production facilities off the Louisiana Gulf Coast

There is little information on denitrification in Gulf of Mexico bottom sediment. Potential denitrification rates in surface sediment were measured along transects legs extending 0–800 m from two offshore oil production platforms. The average potential denitrification ranged from approximately 50 mg N m^?2 d^?1 in surface sediment near the platforms to 15 mg N m^?2 d^?1 in sediment 800 m from the platforms. Measured denitrification rates were correlated to a higher organic matter content in sediment nearer the platforms. This research examined only a small component of nitrogen processing in Gulf of Mexico sediment. Additional research should examine the effect of nitrogen loading and temporal and spatial variability on denitrification rate.     

Sensitive crop species and appropriate bioassays for potential use in phytotoxicity assessment of Pb-contaminated soils

The present study aims to determine the phytotoxic effects of lead (Pb) on corn (Zea mays), wheat (Triticum aestivum), cucumber (Cucumis sativus), cabbage (Brassica oleracea) and lettuce (Lactuca sativa) and to identify the sensitive crop species and appropriate bioassays for potential use in phytotoxicity assessment of Pb-contaminated soil. In a laboratory experiment, Pb(NO₃)₂ was added to the background soil to obtain eight Pb treatments. The results indicate that the seed germination rate of lettuce decreases by 14.44%, 30.00% and 40.00% at 2000, 3000 and 4000 mg Pb kg^?1 soil, respectively. However, the germination of corn, wheat, cucumber and cabbage is not significantly influenced by the Pb-contaminated soil treated with all the tested concentrations. Furthermore, the root elongation is more sensitive to Pb than is seed germination. The minimum concentrations of adverse effect of maize, wheat, cucumber, cabbage and lettuce are 2000, 3000, 1300, 800 and 300 mg Pb kg^?1 soil, respectively. Moreover, dicotyledon species are more sensitive than monocotyledon species. In the genotoxicity study, the mitotic index (MI) fluctuates with an increasing Pb concentration. The micronuclei (MN) frequencies of cucumber, cabbage and lettuce exhibit a dose-dependent effect at concentrations ranging from 1300 to 4000 mg Pb kg^?1 soil. It can be concluded that lettuce is a good candidate for indicating the toxicity of Pb in soil. Root elongation and the micronucleus frequency of dicotyledon are appropriate bioassays for potential use in phytotoxicity assessment of Pb-contaminated soil.     

A predator’s body coloration enhances its foraging profitability by day and night

Few predators forage by both day and night. It remains unknown, however, how the costs and benefits of foraging or signaling are partitioned in animals that forage at all times. The orb-web spider Cyrtophora moluccensis is brightly colored and forages by day and night. We determined the benefits reaped when it forages by both day and night by estimating the biomass of prey caught in their webs. Additionally, we quantified whether the spider’s presence influences the number of prey caught by day and night and whether its colorful body is visible to diurnal and/or nocturnal insects using diurnal and nocturnal insect vision models. We found that approximately five times the biomass of prey was caught in C. moluccensis’ webs by night than by day. Hemipterans, hymenopterans, and dipterans were predominantly caught by day, while lepidopterans (moths) were predominately caught by night. Accordingly, we concluded that foraging by night is more profitable than foraging by day. We predicted that other benefits, for example, energetic advantages or enhanced fecundity, may promote its daytime activity. Foraging success was greater by day and night when the spider was present in the web than when the spider was absent. We also found that parts of the spider’s body were conspicuous to diurnal and nocturnal insects, possibly through different visual channels. The colorful body of C. moluccensis, accordingly, appears to influence its foraging success by attracting prey during both the day and night.     

Characteristics of culturable endophytic bacteria of Xanthoceras sorbifolia Bunge with tumor roots北大核心CSCD

Xanthoceras sorbifolia Bunge with tumor roots was discovered, and the endophytic bacteria that were isolated from the tumor roots were purified and identified. This paper aimed to study the characteristics of endophytic bacteria. The CAS detection plate, Salkowski colorimetry, phosphate solubilizing circle, and molybdenum antimony spectrophotometry were used to analyze endophytic bacteria ability, which produced siderophores, secreted indole-3-acetic acid (IAA), and dissolved phosphorus. Strains were isolated from the tumor roots through morphological and molecular identification, and they were named XSB1-XSB9, of which 6 strains belonged to Bacillus sp., 2 strains belonged to Brevibacillus sp., and 1 strain belonged to Pseudomonas sp. All 9 strains produced siderophores; strains XSB3, XSB4, XSB8, and XSB9 were extremely high yielding, and strains XSB5 and XSB6 were high yielding. The strains with high yields were XSB3, XSB4, XSB5, XSB6, XSB8, and XSB9 and accounted for 66.7% of the tested strains. Nine strains secreted IAA; the concentration of IAA secreted by the strains that contained tryptophan was between 15-50 mg/L, and the concentration of IAA secreted by the one strain without tryptophan was between 10-35 mg/L. The IAA ability of the XSB2, XSB3, XSB4, XSB5, and XSB9 strains were significantly different (P < 0.05) after adding tryptophan. These results indicate that the synthesis of IAA may be the tryptophan synthesis pathway where tryptophan is used as a precursor. All 9 strains had some ability to dissolve phosphorus. The concentration of phosphate in the solubilizing strains, XSB1, XSB2, XSB4, and XSB5, were significantly higher than that in the other strains (P < 0.01), and the concentration of phosphate solubilizing was between 50-90 mg/L; the ability to dissolve phosphate was increased by 19-29 times. The XSB4 and XSB5 strains, which produced siderophores, secreted IAA and had a strong capacity to dissolve phosphorus, may be candidate strains for promoting growth. This research provides the foundation for the development and utilization of rhizosphere microbes to understand the resistance mechanisms and cultivation level of X. sorbifolia. © 2018 Science Press. All rights reserved.     

超滤膜联合高级氧化技术深度处理综合工业污水的研究

采用超滤膜联合高级氧化技术对混合工业园区污水中难降解有机污染物、色度、总大肠菌等进行深度处理。结果表明:运行8周后悬浮物、COD、氨氮、总磷和色度的平均去除率分别为92%、90%、70%,63%和90%,总大肠菌去除率达100%。最终出水水质均可达到城市回用水水质标准。     

低浓度生活污水处理工艺调试运行

介绍了绩溪污水处理厂在低浓度进水条件下的生物启动和调试运行,通过外加碳源虽然可以暂时缓解培养初期活性污泥增长缓慢的问题,但不是长期的运行方式。可以引入部分工业废水至生物处理系统,以提高进水有机底物浓度。但要特别注意避免冲击负荷对系统带来的破坏性影响,同时应根据实际情况灵活调整工艺参数。     

O(~1D)与CF_2CIBr的反应研究

本文研究了CF_2ClBr-O_3体系在253.7nm紫外光照下所引发的O(~1D)与CF_2ClBr的反应.O(~1D)与CF_2ClBr反应的最终产物为CF_2O,Cl_2,Br_2;实验中得到O(~1D)与CF_2ClBr的反应速率常数为1.01×10~(-10)cm~3·molecule~(-1)·s~(-1),并且对O(~3P)与CF_2ClBr的反应可能性以及 O(~1D)与CF_2ClBr的反应机理进行了讨论.     

Divergent effects of climate change on the egg-laying opportunity of species in cold and warm regions

Climate warming can substantially impact embryonic development and juvenile growth in oviparous species. Estimating the overall impacts of climate warming on oviparous reproduction is difficult because egg-laying events happen throughout the reproductive season. Successful egg laying requires the completion of embryonic development as well as hatching timing conducive to offspring survival and energy accumulation. We propose a new metric—egg-laying opportunity (EO)—to estimate the annual hours during which a clutch of freshly laid eggs yields surviving offspring that store sufficient energy for overwintering. We estimated the EO within the distribution of a model species, Sceloporus undulatus, under recent climate condition and a climate-warming scenario by combining microclimate data, developmental functions, and biophysical models. We predicted that EO will decline as the climate warms at 74.8% of 11,407 sites. Decreasing hatching success and offspring energy accounted for more lost EO hours (72.6% and 72.9%) than the occurrence of offspring heat stress (59.9%). Nesting deeper (at a depth of 12 cm) may be a more effective behavioral adjustment for retaining EO than using shadier (50% shade) nests because the former fully mitigated the decline of EO under the considered warming scenario at more sites (66.1%) than the latter (28.3%). We advocate for the use of EO in predicting the impacts of climate warming on oviparous animals because it encapsulates the integrative impacts of climate warming on all stages of reproductive life history.