Potential dissemination mechanism of the tetC gene in Aeromonas media from the aerobic biofilm reactor under oxytetracycline stresses

The tetC gene has been found to be one of the most widely distributed tetracycline resistance (tet) genes in various environmental niches, but the detailed dissemination mechanisms are still largely unknown. In the present study, 11 tetC-containing Aeromonas media strains were isolated from an aerobic biofilm reactor under oxytetracycline stresses, and the genome of one strain was sequenced using the PacBio RSII sequencing approach to reveal the genetic environment of tetC. The tetC gene was carried by an IS26 composite transposon, named Tn6434. The tetC-carrying Tn6434 structure was detected in all of the A. media strains either in a novel plasmid pAeme2 (n=9) or other DNA molecules (n=2) by PCR screening. The NCBI database searching result shows that this structure was also present in the plasmids or chromosomes of other 13 genera, indicating the transferability of Tn6434. Inverse PCR and sequencing confirmed that Tn6434 can form a circular intermediate and is able to incorporate into a preexisting IS26 element, suggesting that Tn6434 might be responsible for the dissemination of tetC between different DNA molecules. This study will be helpful in uncovering the spread mechanism of tet genes in water environments.     

非等压下考虑渗流和剪胀的圆巷围岩弹塑性统一解

对于富水地层中深埋圆形巷道,为研究多种因素影响下巷道围岩塑性区范围和洞周位移的变化规律,对巷道围岩进行了弹塑性理论分析。对围岩应力场和渗流场进行耦合分析,基于统一强度理论和非关联流动法则,推导出多种因素影响下深埋圆形巷道围岩应力、位移和塑性区半径的解析计算式。结合工程实例进行计算分析,结果表明:中间主应力参数、围岩侧压系数、初始孔隙水压和剪胀角对围岩塑性区径向位移和塑性区范围均有显著影响,但影响规律各不相同;考虑中间主应力作用时,其他各因素的影响效应减弱。综合考虑以上各因素对围岩稳定性的影响,计算结果更加接近工程实际情况。     

Provisional drivers' perceptions of the impact of displaying P plates

Objective: P plates (or decals) identify a driver's license status to other road users. They are a compulsory part of the graduated driver licensing system in Queensland, Australia, for drivers on a P1 (provisional 1) or P2 (provisional 2) license. This study explored the perceptions of young drivers regarding the display of P plates (decals) in Queensland, Australia.

Methods: In this study, 226 young drivers with a provisional (intermediate/restricted) license completed a 30-min online survey between October 2013 and June 2014. t Tests were used to compare the opinions of people who displayed their plates nearly always with those who displayed them less frequently.

Results: Participants approved of the requirement to display P plates with 69% of those on a P1 license and 79% on a P2 license supporting the condition to display P1 (red) plates. Participants on a P1 license (62%) and a P2 license (68%) also approved the requirement to display P2 (green) plates. However, young drivers also perceived that the display of P plates (measured from 1 = never to 5 = nearly all the time) enabled newly licensed drivers to be targeted by police and other drivers (those who do not always display P plates: M = 3.72, SD = 0.94; those who nearly always display P plates: M = 3.43, SD = 1.09).

Conclusions: The study findings suggest that participants who nearly always display their P plates are more likely to report that having to display their plates resulted in them driving more carefully.     

发展中水造福人民

介绍了发展中水的重要性,认为应从建立法规政策、充足技术储备、加大宣传力度几方面推广中水。     

苯系有机中间体废水治理技术现状与发展

对苯系有机中间体生产的废水治理技术及工业化应用情况做了较详细的综述，并对今后发展提出建议。     

废水处理中的非传统脱氮途径

根据实验室小型SBR试验的结果，证实存在其它不同于传统的硝化和反硝化的脱氮途径。结合近几年来在生物脱氮理论方面新的研究进展，指出研究非传统脱氮途径的必要性和重要性，其中很有必要的一项工作是需对硝化、反硝化和脱氮过程作出明确的定义。     

二氧化碳氢化固定反应催化剂的研究

研究了Cu、Zn、Al、Cr等氧化物催化剂在二氧化碳氢化固定反应中的催化活性.研究结果表明,一般含铜的催化剂都具有较高的活性和选择性.红外光谱证实二氧化碳加氢反应过程中有甲酸铜中间产物生成,并利用TPD技术对反应物的吸附过程进行了探讨.     

城镇粪便、易腐性生活垃圾、生活污水真空分类收运系统及资源化

对我国城镇粪便、易腐性生活垃圾、生活污水传统排放和处理模式的缺陷和存在的问题进行了分析。提出城镇粪便、易腐性生活垃圾、污水新型分类收运及快速制造有机复合肥系统，对其流程、原理、技术指标和社会、生态、经济意义做了简明的介绍，并与传统重力冲水排污系统从多方面进行了比较。     

拉氏中值定理的发现与证明

给出了拉氏中值定理的发现过程和一个新的证明方法．     

络合萃取法处理高浓度H酸废水

研究了用络合萃取法回收H酸废母液中染料中间体的多种影响因素，得出了最佳工艺参数。实验结果表明，通过萃取工艺，H酸废母液中染料中间体回收率可达90％以上，萃余液中CODcr d (1000-3000)mg/L之间，此工艺可使废母液中的回收物浓缩5－10倍，萃取剂可以再生回用。