Induced temperature-dependent DNA degradation by C_(60) without photoactivation

This study shows that C₆₀ can degrade pBR322 plasmid DNA at room temperature without photoactivation. The degradation was enhanced by increasing incubation temperature, reaction time or C₆₀ concentration. We also found that superoxide radical anions （O 2 · ） were formed in the C₆₀ solution. Superoxide dismutase significantly inhibited DNA cleavage and O 2 · generation induced by C₆₀ . These results suggest that DNA cleavage was caused by the formation of reactive oxygen species induced by C₆₀ at room temperature. Furthermore, we demonstrate that the DNA degradation was significantly inhibited by acid amide chemicals such as formamide, and by increased ionic strength of the reaction solution. These results indicate that the DNA conformation stability and the surface properties of C₆₀ are important factors regulating DNA degradation. We propose that C₆₀ can bind DNA, decrease DNA conformation stability, and induce the formation of reactive oxygen species and DNA cleavage at room temperature. Our results provide a possible explanation for the genotoxicity of C₆₀ , which should be considered in future use of this particular nano-material.     

Use of Geochemical and Geophysical Techniques to Characterize and Prospect for Geothermal Resources and Hydrothermal Ore Deposits

Fluid-rock interactions alter the geochemical, isotopic, petrographic and physical character of host rocks, producing a permanent record of hydrothermal activity. Maps of altered rock properties show r...     

O_2在Pd_2@Au/Pd(100)表面上分解机理研究

采用密度泛函理论,在slab模型下,研究了O2分子在Pd2@Au/Pd(100)表面上的吸附与分解.结果表明:O2分子优先吸附于Pd-Pd桥位,O-O键轴平行于表面.O2分子通过其3σg和1πu轨道向表面转移电荷,又通过其1πg轨道接受来自表面的电子,净的结果是每个O原子得到了0.22e.合金表面暴露出来的Pd二聚体团簇为催化分解O2的活性中心.O2分子在Pd2@Au/Pd(100)表面上分解时,首先需要在扩散中断裂O-O键,然后经过一系列O原子的扩散过程,达到稳定的产物结构.     

ABA和GA刺激的ROS代谢调节水稻幼根伸长分析

本文探索水稻幼根生长过程中ABA和GA对ROS代谢的影响,结果显示:低于0.5μmol/L的ABA促进根伸长,超过此浓度的ABA抑制根伸长;H2O2与ABA相似,低浓度促进而高浓度抑制;在观察浓度范围内,GA促进根伸长.利用3,3'-二氨基联苯胺(diaminobenzidine,DAB)组织化学染色方法检测根尖部位H2O2代谢情况,结果显示,对照、ABA,GA和ABA+GA处理后,根尖分别呈现浅黄色、深棕色、黄色和深棕色,说明ABA比GA诱导较多H2O2产生.进一步研究发现,ABA和ABA+GA分别上调过氧化物酶(peroxidase,POD)活性13.4%和8.37%,GA下调POD活性19.0%;同时,ABA和ABA+GA处理分别下调过氧化氢酶(catalase,CAT)活性14.8%和16.3%,GA则上调CAT活性5.16%.以上结果表明,ABA可能通过上调POD和抑制CAT活性来提高ROS含量,而GA与之相反,严谨控制ROS浓度,促进水稻生长.     

透氧纤维素膜的制备及其性能研究

以NMMO(N–甲基吗啉–N–氧化物)工艺为基础,在纤维素溶液中加入CaCO3并在成膜后酸洗去除,制备具有适当透气度的纤维素膜.通过控制CaCO3的粒径和添加量,探讨纤维素膜透氧性能和拉伸性能的变化.结果表明:随着CaCO3的加入,纤维素膜的透氧系数增大,拉伸强度、断裂伸长率和透明度总体呈下降趋势.CaCO3添加量一定时,CaCO3粒径越大,透氧系数越大,拉伸强度和透明度越小.     

对苯二酚对亚硫酸盐防腐蚀效果的影响

通过除氧试验、腐蚀试验和电化学试验，研究了对苯二酚对亚硫酸盐防腐蚀效果的影响。结果表明，对苯二酚使亚硫酸盐几乎失去了除氧作用，但却提高了亚硫酸盐在含氧水中对２０ｇ钢的防腐蚀性能，使钢的自腐蚀电位更剧烈负移并使阴极极化增加。     

富磷污泥的处理与水体富营养化的预防

城市污水和工业废水中含有的氮、磷等植物性营养物质是导致湖泊等缓流水体富营养化的主要原因。通过绝氧－好氧活性污泥法去除ＢＯＤ的同时也去除引起水体富营养化的盐－磷，以抑制水生植物繁衍，达到防止水体富营养化的目的。     

一次性使用的氧气湿化瓶细菌学调查及对策

调查一次性氧气湿化瓶使用中湿化液的细菌学分布.以普通氧气湿化瓶为对照组,采集ICU病房和老年病病房中湿化瓶使用前和使用后1~7 d的湿化液,进行细菌计数和细菌分离鉴定.对照组于使用后第2天就可检出细菌,一次性氧气湿化瓶组至第7天才能检出细菌,一次性氧气湿化瓶组细菌数明显低于对照组.对照组共检出35株细菌,一次性氧气湿化瓶组共检出5株细菌,以条件致病菌为主.一次性氧气湿化瓶能降低污染,减少院内感染,值得在临床中推广使用.