Anaerobic biodegradation of trimethoprim with sulfate as an electron acceptor

Anaerobic biodegradation of trimethoprim (TMP) coupled with sulfate reduction. Demethylation of TMP is the first step in the acclimated microbial consortia. The potential degraders and fermenters were enriched in the acclimated consortia. Activated sludge and river sediment had similar core microbiomes. Trimethoprim (TMP) is an antibiotic frequently detected in various environments. Microorganisms are the main drivers of emerging antibiotic contaminant degradation in the environment. However, the feasibility and stability of the anaerobic biodegradation of TMP with sulfate as an electron acceptor remain poorly understood. Here, TMP-degrading microbial consortia were successfully enriched from municipal activated sludge (AS) and river sediment (RS) as the initial inoculums. The acclimated consortia were capable of transforming TMP through demethylation, and the hydroxyl-substituted demethylated product (4-desmethyl-TMP) was further degraded. The biodegradation of TMP followed a 3-parameter sigmoid kinetic model. The potential degraders (Acetobacterium, Desulfovibrio, Desulfobulbus, and unidentified Peptococcaceae) and fermenters (Lentimicrobium and Petrimonas) were significantly enriched in the acclimated consortia. The AS- and RS-acclimated TMP-degrading consortia had similar core microbiomes. The anaerobic biodegradation of TMP could be coupled with sulfate respiration, which gives new insights into the antibiotic fate in real environments and provides a new route for the bioremediation of antibiotic-contaminated environments.     

微电脑烟尘采样器的使用

根据作者在仪器使用和维修过程中的一些经验,介绍TH880Ⅳ型智能烟尘平行采样仪在实际应用中遇到的问题,并提出相应的解决方法及建议。     

农业旱灾形成过程中的承灾体脆弱性分析--以湖南鼎城为例

农业旱灾的形成是降水不足或不均与农业生产系统脆弱性共同作用的结果,承灾体脆弱性的高低会起到“放大“或“缩小“灾情的作用,因此降低承灾体的脆弱性是抗灾减灾的主要和有效途径.选择湖南省鼎城区为研究区,通过分析灾前期-灾中期旱灾的形成过程及其与承灾体脆弱性的关系,分别针对轻度干旱和中重度干旱建立了评价指标体系,采用加权求和法对水田-水稻农业生产系统的脆弱性进行了评价.结果表明,该区的承灾体脆弱性分布存在一定的区域差异,脆弱度由高至低排序为西北岗地区、南部低山/丘陵区、中部平原/岗地区、东北湖/平原区,这一分析结果与实际灾情的分布规律基本一致.通过分析脆弱性分布规律和变化原因,发现地形和灌溉分别是影响灾前期和灾中期承灾体脆弱性的最重要因素,进而提出了具体的减灾防灾建议.     

Effects of Duststorms on the Air Pollution in Beijing

The objective of this study was to investigate the air pollutionin Beijing before, during, and after duststorms occur. There aretwo different phenomena of air pollution in Beijing during a duststorm; one being related to the concentration of particulatematter and the second related to gaseous chemical pollutant concentrations. In this study, the concentrations of the chemicalpollutants, such as SO₂, NO_x and CO, were high prior to the occurrence of the duststorms. At the beginning of the two duststorms studied, the air quality related to these chemicalconstituents was improved due to a strong wind blowing away the chemical pollutants, which caused a decrease in the concentrations of SO₂, CO and NO_x. During the duststorm, the concentration of particulate matter, quantified by PM₁₀, wasobserved to increase and the atmospheric visibility decreased.     

生物吸附法处理含铀废水研究进展

生物吸附法处理含铀废水是新兴的研究领域。本文介绍了吸附铀的生物材料的来源以及影响吸附过程的各种因素，总结了生物吸附的机理、生物材料的改性和固定化、生物吸附的数学模型等方面的研究进展。     

重庆市城市污泥的质量现状及利用对策

重庆市城市污泥产生量大，污泥的集中处理能力小，污泥中重金属的质量状况较好，N、P、K、有机质的含量高，综合利用潜力大，开发潜力巨大。     

废旧车用载钯催化剂中钯的浸出研究

针对汽车尾气的污染,汽车排气系统都安装有含铂族金属的汽车催化剂.废旧汽车催化剂已成为铂族金属重要的二次资源.本文采用湿法浸出整体式蜂窝陶瓷汽车催化剂中的铂族金属钯.氧化焙烧废汽车催化剂除去积炭和其他有机物,再磨细过筛100目后烘干.预处理过的废催化剂用还原剂HCOOH溶液将催化剂中氧化态钯转化为单质钯,在70℃恒温下,用盐酸和氧化剂NaClO3选择性浸出钯.本文比较了几种浸出方法的结果,考察了HCl-NaClO3浸出体系的几个因素对钯浸出的影响,确定了最佳浸出条件.实验结果表明,HCl-NaClO3浸出体系在优化条件下能完全浸出催化剂中的钯,该方法可以用于钯的回收和对催化剂中的钯进行定量分析.     

一种用于Ad hoc网络安全的新型混合式CA服务体系

由于Adhoc网络的无线分布和自组织特性 ,使得网络安全显得更为脆弱 ;同时由于Adhoc网络的无中心和计算性能受限特性 ,使得安全体系难以布设。笔者分析了传统CA体系和分布式CA体系各自的优缺点 ,提出了一种用于Adhoc网络的新型混合式CA服务体系。该混合式CA服务体系把证书颁发和证书管理分开 ,一方面具有了传统CA体系的安全性 ,另一方面减轻了Adhoc网络的计算负荷。同时对分布式证书管理中的证书撤销、证书验证、表的维护和更新作了详细的分析 ,并利用可信度系数α对证书的可信性进行描述 ,增加了分布式证书管理的可靠性和灵活性。     

Physical Properties of Chemically Modified Starch(RS4)/PVA Blend Films—Part 1

In this paper, we report on the physical properties of films that have been synthesized by using native corn starch (NS) and chemically modified starch (RS4). NS or RS4/PVA blend films were synthesized by using the mixing process and the casting method. Glycerol (GL), sorbitol (SO), and citric acid (CA) were used as additives. The chemically modified starch (RS4) was synthesized by using sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) as a crosslinker. Then, the RS4 thus synthesized was confirmed by using the pancreatin-gravimetric method, swelling power and an X-ray diffractometer (XRD). Tensile strength (TS), elongation (%E), swelling behavior (SB), and solubility (S) of the films were measured. The result of the measurements indicated the RS4-added film was better than the NS-added film. Especially, the RS4/PVA blend film with CA as an additive showed the physical properties superior to other films.     

湿式石灰/石灰石烟气脱硫工艺存在的问题及技术措施

正确处理湿式石灰／石灰石烟气脱硫（FGD）过程的石膏结垢、设备腐蚀等问题，是保证FGD系统长期稳定可靠运行的关键。本文对湿式石灰／石灰石FGD过程中的石膏结垢成因、设备腐蚀原因、烟气再热以及与液固分离等相关的亚硫酸盐的氧化等问题进行了分析，归纳对比了现行技术措施的优缺点。结合我国国情，综合考虑技术可行性和经济合理性等因素，就解决这些问题应采取的适宜措施提出了见解。