Responses of bacterial strains isolated from drinking water environments to N-acyl-L-homoserine lactones and their analogs during biofilm formation

Often as a result ofbiofilm formation, drinking water distribution systems （DWDS） are regularly faced with the problem of microbial contamination. Quorum sensing （QS） systems play a marked role in the regulation of microbial biofilm formation; thus, inhibition of QS systems may provide a promising approach to biofilm formation control in DWDS. In the present study, 22 bacterial strains were isolated from drinking water-related environments. The following properties of the strains were investigated： bacterial biofilm formation capacity, QS signal molecule N-acyl-L-homoserine lactones （AHLs） production ability, and responses to AHLs and AHL analogs, 3-chloro-4-（dichloromethyl）-5-hydroxy-2（5H）- furanone （MX） and 2（5H）-furanone. Four AHLs were added to developed biofilms at dosages ranging from 0.1 nmol.L J to 100nmol.L1. As a result, the biofilm growth of more than 1/4 of the isolates, which included AHL producers and non-producers, were significantly promoted. Further, the biofilm biomasses were closely associated with respective AHLs concentrations. These results provided evidence to support the idea that AHLs play a definitive role in biofilm formation in many of the studied bacteria. Meanwhile, two AHLs analogs demon- strated unexpectedly minimal negative effects on biofilm formation. This suggested that, in order to find an applicable QS inhibition approach for biofilm control in DWDS, the testing and analysis of more analogs is needed.     

Neighborhood form and CO2 emission: evidence from 23 neighborhoods in Jinan, China

To understand the household C02 emission level in China, as well as how much the neighborhoods＇ socio-economic or design factors could influence the CO2 emission, 23 neighborhoods in Jinan were investigated in 2009 and 2010. These neighborhoods fall into four different types： superblock, enclave, grid and traditional. The household CO2 emission includes sources of both in- home energy use and passenger transportation. The average CO2 emission per household is 7.66 t.a^-1, including 6.87 t in-home operational emission and 792 kg transportation emission. The household CO2 emission by neighborhood categories is 10.97, 5.65, 6.49, 5.40 t-household-1. a-1 for superblock, enclave, grid and tradi- tional respectively. Superblock has the highest average emission and also the highest percent （more than 25%） of transportation emission among four different types of neighborhoods. The residential CO2 emission of superb- lock neighborhoods in Jinan has already reached the level in developed countries nearly ten years ago. It is predictable that more superblock neighborhoods would be built in China with the fast urbanization. How to avoid the rapid household CO2 emission growth in the future would be a systematic issue. The study also found that in addition to income and apartment area, household density, land use mix and accessibility to public transportation are three primary factors which have significant impacts on CO2 emission. High density, mixed land use and convenient accessibility to public transportation tend to reduce household CO2 emission.     

采用TSF技术改善电力变压器运行的安全性

分析了无功功率和高次谐波对电力变压器的危害,介绍了晶闸管投切滤波器(TSF)装置的特点、结构原理．提出了TSF装置在工厂实际应用中的主电路结构,操作及控制方案。实践证明,TSF晶闸管投切滤波器装置起到了高效节能、优化电能质量的作用,保证了电网的安全运行。     

紫外消毒在城市污水处理中的研究进展

介绍城市污水消毒的必要性,对常用污水消毒技术进行现状分析及技术经济比较,紫外线消毒有望成为替代传统液氯消毒的较佳选择.阐述紫外线消毒原理及工程上的应用.最后对紫外消毒技术进行总结.     

膜分离技术在环境分析中的应用

膜分离技术在环境分析中起着十分重要的作用。本文对滤膜分离、渗透汽化膜、渗析法、电渗析法、液膜分离等分离技术在水、土、气和生物样品中阴离子、阳离子、金属元素、有机物、生物毒素等指标检测的应用进行了深入介绍。     

典型电解锌冶炼废渣重金属形态及环境效应研究

电解锌冶炼废渣收集、转移、贮存与利用处置过程的环境管理是困扰铅锌冶炼行业的瓶颈问题之一.对典型电解锌冶炼各工艺段废渣及原矿中的重金属组成与赋存形态进行了研究,并在此基础上研究了废渣的环境效应和生物有效性.结果表明,典型电解锌冶炼原矿中存在高含量的Zn、Pb等重金属元素,各工艺段废渣中Zn、Pb、Cd和M n等元素含量较...     

基于ANSYS的界面化核电站取水构筑物配筋程序开发

在实际工程应用中,对于结构复杂安全等级高的核电水工结构,相关的通用设计软件尚未形成。利用ANSYS二次开发工具APDL、UIDL以及Tcl/Tk可视化工具命令语言,针对核电站取水构筑物开发了一整套程序,包括了建模、计算以及后处理,后处理部分为内力计算和配筋可视化程序,简化了操作流程。算例表明,内力提取程序运算结果精度良好,可以用于配筋设计,利用配筋可视化程序对工程实例进行的配筋及裂缝验算,结果符合工程要求,针对配筋结果提出了墙体优化设计的建议。通过在ANSYS中实现内力计算和可视化配筋程序,可用于解决核电水工结构设计问题,有良好的工程适用性。     

Short-term influence of nutrient availability on the uptake and translocation of phenanthrene in mangrove seedlings

Abstract

The uptake and distribution of phenanthrene, a typical polycyclic aromatic hydrocarbon, in plant tissues of Aegiceras corniculatum and Avicennia marina and the relationship with nutrient (nitrate, ammonium, and soluble reactive phosphorus) availability were investigated. After 12?h of exposure, enhancements in the concentration of nitrate and soluble reactive phosphorus markedly decreased the residual level of phenanthrene in roots, while the addition of ammonium significantly increased the residual concentration. Due to the similar enzymatic degradation potential between treatment groups, the variation of phenanthrene concentration in mangrove roots may result from the H⁺/phenanthrene cotransport at the root surface that was influenced by nutrient uptake. Moreover, both nitrate and soluble reactive phosphorus amendments significantly increased translocation of phenanthrene from roots to leaves, which likely resulted from the change of hydraulic conductivity in mangrove plants triggered by different nutrient availability.     

SDA脱硫工艺在烧结烟气脱硫中的应用

介绍了沙钢集团4号360 m2烧结机全烟气脱硫项目的工艺选择、脱硫原理、工艺流程及投产后生产情况,通过对生产后运行分析,认为旋转喷雾干燥法(SDA)作为一种新型的脱硫工艺,适合作为烧结烟气脱硫的主工艺进行推广。     

Biodegradability of organic substances by ATP test

The aerobic biodegradability of organic substances in water is characterized by determination of energy change ‐ ATP content in microbial cells during biodegradation. A satisfactory result is obtained under the following conditions: the initial concentration of tested substance is 100mg/l (as DOC), the amount of the inoculum in the biological medium is 500mg/l (as MLSS), and the duration of test time is 14 days. The evaluating system (peak time, peak height and IA index) is proposed to assess the biodegradability of 46 organic compounds and 7 wastewaters.