中美气候变化论坛

由美国加州大学伯克利分校和北京大学联合主办的中美气候变化论坛于5月23日至24日在旧金山开幕．有来自中美两国以及欧洲等地的专家学者近200人参加了论坛。     

铝毒在不同作物上的差异及温度的影响

采用水培法研究了作物耐铝性差异及温度对作物铝毒的效应，结果表明，铝首先伤害根生长，抑制作物对养分的吸收和利用，其中对大麦和蕃茄的危害尤为明显，并导致出现缺素症。耐铝能力为水稻＞大豆＞大麦＞蕃茄，而它们的耐铝机理不完全相同。铝对作物的毒害因温度而异，作物在其最适生长温度范围内受铝伤害最明显。作物体内的铝含量有随铝处理浓度增高而增加的趋势，并明显受温度的影响。     

论北京城市建设的综合减灾问题

本文针对北京城市建设面临的自然与人为灾害背景,简要论述了北京地震、水灾、火灾及“新致灾源”的历史及现状,强调开展首都圈灾害研究及减灾规划设计的重要性,并提出了系统的减灾方略及相应的管理构想。     

Physiological recovery from episodic acid stress does not mean population recovery of Gammarus fossarum

The physiological responses of the acid-sensitive amphipod Gammarus fossarum exposed in situ to acid stress (pH4.5 and 5.5) and then transferred back to neutral water were investigated. Survival rate and haemolymph [Cl(-)] and [Na(+)] were assessed after 24, 48 and 72h of exposure in acidic streams and after a recovery period of 12, 24, 36, 48 and 60h. After 24h, exposure to slightly acidic (pH5.5) and strongly acidic water (pH4.5) led to a severe and significant depletion in haemolymph [Na(+)] and [Cl(-)] compared to organisms exposed in circumneutral water (pH7.3). However, after only a 12h-period of transfer back in neutral water and whatever the previous exposure time (24, 48 and 72h) in both slightly and strongly acidic water, haemolymph [Na(+)] and [Cl(-)] were equal or superior to the control level without associated mortality. In spite of this fast physiological recovery capacity, populations of G. fossarum living in streams undergoing episodic acid stresses were drastically affected thus, demonstrating the high acid-sensitivity of this species. We discuss the possible reasons of population regression and the absence of population recovery.     

紫外吸收剂在湖泊中的分布及其对底栖动物的毒性效应

紫外吸收剂大量用于工业材料和个人护理品中,近年来在水体中不断被检出,同时由于其高度亲脂性,易在底泥和水生生物体内富集,产生潜在的毒性效应,已成为一类新型污染物。本文综述了紫外吸收剂在湖泊环境中的分布和生物富集效应,重点分析了二苯甲酮类等典型紫外吸收剂对底栖动物的药物代谢系统、抗氧化系统及其生长发育的影响及其毒性作用机制,并对未来该领域的研究进行了展望。     

浅覆地层盾构开挖面被动破坏极限支护力及破坏模式研究

浅覆地层盾构掘进时支护力过大极易导致开挖面前方土体发生被动破坏,造成地表隆起。基于筒仓理论,通过优化传统三维楔形体模型,建立楔形块+倒棱台的土体被动破坏三维计算模型(修正三维楔形体模型),并推导被动极限支护力计算公式;对不同埋深下滑动破裂角β分析研究;采用有限元分析软件MIDAS-GTS对盾构隧道开挖面的被动破坏进行模拟,揭示被动破坏支护力变化规律及破坏模式。结果表明:本文研究计算模型更符合开挖面土体被动破坏模式;通过对破裂角β分析,解析土体被动破坏时其最优解30°左右;在浅覆盾构开挖面中,揭示S/(γD)受土体内摩擦角φ、埋深比K的影响,文中S/(γD)随内摩擦角φ的增大呈非线性增加,埋深比K越大,其幅度越明显;破坏模式分析中,K越小,土体位移变形对S/(γD)越敏感,越容易发生开挖面被动破坏;发生被动破坏时,土体纵向位移变形大于横向位移变形。     

Investigation on the interaction between triclosan and bovine serum albumin by spectroscopic methods

Abstract

Multi-spectroscopic and molecular docking methods were used to study the interaction between triclosan (TCS) and bovine serum albumin (BSA). The results indicated that the fluorescence quenching of BSA by TCS was due to the formation of TCS–BSA complex through static quenching. This result was also demonstrated by time-resolved fluorescence experiment. The binding constants and number of binding sites between TCS and BSA were 1.30?×?10⁵ M^?1 and 1.17 at 298?K, respectively. The thermodynamic parameters were studied in detail which suggested that hydrophobic forces and hydrogen bond played major roles in the TCS–BSA interaction. Moreover, the site marker competitive experiments and docking studies revealed that TCS could bind BSA into site I in subdomain IIA. All the results of UV–vis spectrophotometry, circular dichroism spectroscopy and synchronous fluorescence spectroscopy showed that interaction between TCS and BSA induced conformation changes of BSA.     

中国与欧洲禾谷镰刀菌DON毒素HPLC定量比较分析

选用4个来自中国、7个来自欧洲的代表性禾谷镰刀菌菌株,经脱氧雪腐镰刀菌烯醇(DON)毒素特异引物鉴定,确认其具有产生DON毒素的遗传物质基础后,接种于PDB培养基培养7d,从培养基上清中经硅胶柱分离、纯化DON毒素,经HPLC定量分析表明,纯化的禾谷镰刀菌DON毒素,与购自公司的DON毒素标准样品一样,其HPLC检测谱峰清晰明显,基线平稳,无干扰,保留时间为9.5min左右;供试菌株的DON毒素含量分布在0.023~1.934μg/mL之间,德国菌株F703产毒量最大,比位居第二的中国菌株5005(1.232μg/mL)高57%;其余的6个欧洲菌株中,除意大利菌株Lor9(0.128μg/mL)略低于另一个中国菌株7105(0.135μg/mL)外,均比3个中国菌株(4020、7105、8029)的产毒量大.欧洲镰刀菌产生DON毒素的能力远远大于中国菌株,这说明欧洲菌株长期在欧洲生态环境下已演变形成其特有的高毒素代谢类型,我国有必要严防欧洲禾谷镰刀菌入侵,加强对来自欧洲的禾谷类粮食及其产品的镰刀菌和毒素的检疫和监控;同时,本研究建立的毒素样品制备与HPLC检测体系可用于准确定量分析样品的DON毒素.图3表2参14     

循环载体生物滤池─—生物过滤新工艺

循环载体生物过滤工艺融三相流化、悬浮曝气、移动接触等几种不同工艺于一体，具有独特的工作原理和工艺特征。动态实验结果表明，循环载体生物过滤工艺容积负荷高，耐冲击负荷能力强，处理效果好，是一种比较理想的生物处理工艺。     

铁催化聚丙烯腈脱氮的研究

应用热天平研究了载铁聚丙烯腈的脱氮碳化行为，负载铁对ＰＡＮ的稳定化和脱氮碳化均具有显著的催化作用，并在５８０－７６０℃范围内明显增加了Ｎ２形成速率。ＸＰＳ和ＸＲＤ对碳化过程中铁和氮化学形态变化的研究结果表明，铁催化反应机理可能是负载铁与吡啶氮作用形成中间体铁氮化物，后者进而分解释放出Ｎ２。