一种异养生物膜(heterogeneous biofilms)活细胞生物量的空间变化

根据文献数据研究了一种正常发育的异养生物膜中活细胞生物量的空间变化特征,运用双自然对数相关分析和分形几何学分析方法发现：异养生物膜中活细胞生物量与生物膜的表面积或面积之间具有显著的双自然对数正相关关系;活细胞生物量在空间上呈现异速生长特性和分形几何学生长特征;活细胞生物量的分维值（D）指示了活细胞生物量在生物膜中空间分布的非均匀程度,并因随生物膜发育阶段变化而能够指示生物膜系统的发育演化进程,将生物膜活细胞生物量和分形几何学结合起来,提供了一种相对目前流行的像素分析法更为简便的认识生物膜空间结构及其变化的新方法。     

在流动式电解槽中氨氮废水的间接电氧化

研究了氨氮废水在流动式电解槽中的间接电化学氧化,讨论了氯离子浓度、电解液流速、氨氮初始浓度对氨氮去除的影响结果表明,氯离子浓度和电解液流速对氨氮的去除速率有很大的影响当电流密度为50mA·cm-2、流速为50ml·min-1时,氨氮去除速率常数为389×10-5g·l-1·m-1·s-1,去除1kg氨的氮能耗为557kWh     

Survey of mercury,cadmium and lead content of household batteries

The objective of this work was to provide updated information on the development of the potential impact of heavy metal containing batteries on municipal waste and battery recycling processes following transposition of the new EU Batteries Directive 2006/66/EC. A representative sample of 146 different types of commercially available dry and button cells as well as lithium-ion accumulators for mobile phones were analysed for their mercury (Hg)-, cadmium (Cd)- and lead (Pb)-contents. The methods used for preparing the cells and analysing the heavy metals Hg, Cd, and Pb were either developed during a former study or newly developed. Several batteries contained higher mass fractions of mercury or cadmium than the EU limits. Only half of the batteries with mercury and/or lead fractions above the marking thresholds were labelled. Alkaline–manganese mono-cells and Li-ion accumulators, on average, contained the lowest heavy metal concentrations, while zinc–carbon batteries, on average, contained the highest levels.     

Ultrastructure effects of omethoate and cypermethrin insecticides on maize seedlings

Increasing studies suggest that insecticides are one of the plant stress elements that affect plant growth and productivity by interfering with cell metabolic and biochemical activities. Here, we show that the application of commonly used pesticides omethoate and cypermethrin on maize (Zea mays L. cv. Luyu 9) seedling leaves resulted in adverse effects on leaf ultrastructure changes under laboratory conditions. Electron microscopic studies reveal that the topical application of organophosphorus insecticide omethoate causes direct injury of leaf ultrastructures including cell wall breakdown of abaxial epidermis cells, inner cells, stomata guard cells; degradation of mitochondrial membrane, and chloroplast envelope membrane; and abnormal changes of lamella arrangement of chloroplast. And the topical application of cypermethrin insecticide causes plasmolysis of cells of the adaxial epidermis, mitochondrial cristae are degraded, and loosen arranged lamella of amyloplasts. All these changes indicated that omethoate and cypermethrin are stress factors that caused adverse effects on plant ultrastructures and biochemical molecules.     

Modeling the current-voltage characteristics of thin-film silicon solar cells based on photo-induced electron transfer processes

Power conversion efficiency of p-i-n type microcrystalline silicon (c-Si:H) solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. The effect of the excitonic state on the charged carrier generation has been studied compared to a conventional scheme in which only charged carriers are taken into account for the operation of the solar cells. A numerical model has been developed to calculate current-voltage characteristics of solar cells on the basis of two types of charged carrier generation processes (exciton process and charged carrier process). The light trapping effect due to a textured back surface reflector (BSR) was embedded in the numerical model by using the effective medium theory in combination with the matrix method in the field of the electromagnetic theory of light. As an application of this modeling, it was found that the reported data of the power conversion efficiency were not explained by the conventional charged carrier process model and that the combined model of the charged carrier process with the exciton process well explains the performance of the p-i-n type c-Si:H solar cells. In this way, the typical power conversion efficiencies were estimated to be 10.5% for the device (i-layer thickness: 1.8 m) with the BSR (period: 600 nm; height: 250 nm) and 8.6% for the device with the flat reflector under the condition that the fractions of the exciton process and charged carrier process were 60% and 40%, respectively.     

Modeling the current-voltage characteristics of thin-film silicon solar cells based on photo-induced electron transfer processes

Power conversion efficiency of p-i-n type macrocrystalline silicon (µc-Si:H) solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. The effect of the excitonic state on the charged carrier generation has been studied compared to a conventional scheme in which only charged carriers are taken into account for the operation of the solar cells. A numerical model has been developed to calculate current-voltage characteristics of solar cells on the basis of two types of charged carrier generation processes (exciton process and charged carrier process). The light trapping effect due to a textured back surface reflector (BSR) was embedded in the numerical model by using the effective medium theory in combination with the matrix method in the field of the electromagnetic theory of light. As an application of this modeling, it was found that the reported data of the power conversion efficiency were not explained by the conventional charged carrier process model and that the combined model of the charged carrier process with the exciton process well explains the performance of the p-i-n type μc-Si:H solar cells. In this way, the typical power conversion efficiencies were estimated to be 10.5% for the device (i-layer thickness: 1.8 μm) with the BSR (period: 600 nm; height: 250 nm) and 8.6% for the device with the flat reflector under the condition that the fractions of the exciton process and charged carrier process were 60% and 40%, respectively.     

CaO2促进MFC同步处理剩余污泥和六价铬废水的效能

为了提高剩余污泥降解效能和废水中六价铬还原效能,研究了CaO₂对微生物燃料电池同步处理剩余污泥和六价铬废水的影响,考察了不同CaO₂投加量下微生物燃料电池阳极剩余污泥的降解效能、阴极六价铬的还原效能及产电效能.结果表明,当阳极室CaO₂投加量分别为0,0.1,0.2,0.4,0.6,0.8gCaO₂/gVSS时,运行120h后,阴极六价铬还原率分别为73.38%,78.91%,99.47%,97.70%,97.04%,96.37%,运行30d后,阳极剩余污泥TCOD降解率分别为72.4%,76.9%,81.0%,78.2%,75.7%,74.2%.证明投加CaO₂后,六价铬还原率和TCOD降解率都有提高.当投加量为0.2gCaO₂/gVSS时处理效能最好,输出电压最大为1.15V.六价铬还原率提高了36.08%,TCOD降解率提高了11.88%.此外,投加CaO₂后微生物燃料电池电化学活性有所提高,表明CaO₂投加对电池电子传递过程有促进作用.结果说明CaO₂有利于提高对微生物燃料电池同步处理剩余污泥和六价铬废水效能.     

Nitrite pre-treatment of dewatered sludge for microbial fuel cell application

The effect of pre-treatment of dewatered sludge using different nitrite concentrations and pH for microbial fuel cell (MFC) application was investigated. The results show that the addition of nitrite was feasible to increase the solubilization rate of the sludge and may reduce mass transfer limitation at the anode. This helped the MFC to reach higher voltage and to generate more power. The higher free nitrous acid (FNA) concentration under the acidic condition helped to increase sludge solubilization. However, under an alkaline condition, during which the FNA concentration was relatively low, the solubilization of the sludge was higher. The highest voltage and power density produced was 390?mV and 153?mW/m², respectively, with the addition of nitrite at 100?mg-N/L and pH?9. Furthermore, it was found that elevated levels of FNA could inhibit electrogenic bacteria thus reducing power generation.     

A strategy for enhancing anaerobic digestion of waste activated sludge: Driving anodic oxidation by adding nitrate into microbial electrolysis cell

Cathodic reduction of CO₂ and anodic oxidation of organic matters are crucial to methane-producing microbial electrolysis cell (MEC) applied in anaerobic digestion of waste activated sludge. However, cathodic CO₂ reduction is usually restrained by slow metabolism rates of H₂-utilizing methanogens and low electron-capturing capacity of CO₂, which consequently slows down the anodic oxidation that participates to sludge disintegration. Herein, a strategy with adding nitrate as electron acceptor to foster electronic transfer between the anode and cathode was proposed to improve anodic oxidation. Results showed that the average efficiency of anodic oxidation in the nitrate-added MEC increased by 55.9%. Accordingly, volatile suspended solid removal efficiency in the nitrate-added MEC was 21.9% higher than that of control MEC. Although the initial cumulative methane production in the nitrate-added MEC was lower than that of control MEC, the cumulative methane production in 24?days was 8.9% higher. Fourier transform infrared spectroscopy analysis indicated that anodic oxidation of MEC with nitrate accelerated the disintegration of sludge flocs and cell walls. Calculation on current signal further revealed that anodic oxidation driven by cathodic nitrate reduction was the main mechanism responsible for the improved sludge digestion.     

石墨烯掺杂聚苯胺阳极提高微生物燃料电池性能

微生物燃料电池（microbial fuel cell,MFC）技术可分解代谢污染物质并同步输出电能,在环境及能源领域吸引了越来越多的关注.但是,输出功率密度较低、成本较高、底物降解率低等特点限制了其实际应用,其中阳极是主要限制因素之一.本研究选取具有优异导电性、大比表面积的石墨烯和生物相容性较好的聚苯胺（polyaniline,PANI）,并优化二者比例关系,制备得到石墨烯掺杂PANI复合材料.将复合材料涂覆在玻碳电极表面分析电化学性能,循环伏安（cyclic voltammetry,CV）和线性伏安扫描（linear sweep voltammetry,LSV）测试结果均显示石墨烯含量占比20%的复合电极（20%石墨烯）电化学性能最好.将复合材料修饰在碳布表面作为MFC阳极时以石墨烯含量占比5%的复合电极（5%石墨烯）生物电化学性能最佳,LSV得到最大输出功率密度为（831±45）mW·m^-2,分别是20%石墨烯、1%石墨烯、石墨烯、PANI、碳布阳极的1.2、1.3、1.3、1.5、1.8倍.最大输出电压、开路电压、化学需氧量去除率、库仑效率、生物量密度均以5%石墨烯电极最高.电化学阻抗分析表明5%石墨烯电极极化内阻仅为（24±2）Ω,是碳布电极的19.8%.电化学和生物电化学性能并不完全一致,说明电极材料的生物相容性是影响MFC性能的主要因素之一.5%石墨烯阳极充分发挥了石墨烯和聚苯胺的优点,提高了MFC的产电性能.