海洋沉积物中现存微生物化学标志物完整极性膜脂研究进展   总被引：3，自引：0，他引：3  

姚鹏  于志刚 《地球科学进展》2010,25(5):474-483

完整极性膜脂作为活的微生物细胞的化学标志物,能够反映海洋沉积物中现存微生物群落结构和生物量等信息.与生物学方法相比,完整极性膜脂分析技术具有无需培养、快速和普适性等特点.综述了海洋沉积物中细菌和古菌的细胞膜完整极性膜脂的组成特点及其在生物地球化学和微生物生态学等研究中的应用,重点评述了在生物地球化学循环中有特殊作用的微生物,如厌氧氨氧化细菌、甲烷氧化古菌、氨氧化古菌、具有四醚膜脂结构的海洋泉古菌等,或者是一些特殊生态系统,如冷泉、海底深部生物圈等研究中完整极性膜脂应用的进展.还简要介绍了完整极性膜脂的分析方法,并对其应用前景进行了展望.  相似文献   

Maintaining the stability of deviated and horizontal wells: Effects of mechanical,chemical and thermal phenomena on well designs     

《Geomechanics and Geoengineering》2013,8(3):167-178

Wellbore instability, particularly in shale formations, is regarded as a major challenge in drilling operations. Many factors, such as rock properties, in-situ stresses, chemical interactions between shale and drilling fluids, and thermal effects, should be considered in well trajectory designs and drilling fluid formulations in order to mitigate wellbore instability-related problems. A comprehensive study of wellbore stability in shale formations that takes into account the three-dimensional earth stresses around the wellbore as well as chemical and thermal effects is presented in this work. The effects of borehole configuration (e.g. inclination and azimuth), rock properties (e.g. strength, Young's modulus, membrane efficiency and permeability), temperature and drilling fluid properties (e.g. mud density and chemical concentrations) on wellbore stability in shale formations have been investigated. Results from this study indicate that for low-permeability shales, chemical interactions between the shale and water-based fluids play an important role. Not only is the activity of the water important but the diffusion of ions is also a significant factor for saline fluids. The cooling of drilling fluids is found to be beneficial in preventing compressive failure. However, decreasing the mud temperature can be detrimental since it reduces the fracturing pressure of the formation, which can result in lost-circulation problems. The magnitude of thermal effects depends on shale properties, earth stresses and wellbore orientation and deviation. Conditions are identified when chemical and thermal effects play a significant role in determining the mud-weight window when designing drilling programmes for horizontal and deviated wells. The results presented in this paper will help in reducing the risks associated with wellbore instability and thereby lowering the overall non-productive times and drilling costs.  相似文献   

缘于任意自旋场的Vaidya黑洞的熵(英文)     

SHEN Yougen GAO Changjun 《中国科学院上海天文台年刊》2003,(1)

用在brick模型基础上发展起来的membrane模型 ,计算了缘于任意自旋场的非静态黑洞———Vaidya黑洞的自由能和熵。结果表明 ,玻色子场 (自旋s =1,2 )和费米子场 (自旋s =1/2 )的熵都恰好与黑洞的视界面积成正比 ,这与静态和稳态的情况相同。而且 ,玻色子和费米子场的熵具有相同的形式 ,二者相差一个系数  相似文献   

Aspects of the usefulness of five marine pollution biomarkers, with emphasis on MN and lipid content     

Koukouzika N  Dimitriadis VK 《Marine pollution bulletin》2008,56(5):941-949

By using cellular biomarkers, such as the formation of the micronucleus, the morphometric alterations of lipids and the morphometric changes in the lysosomal system, we investigated effects of experimental exposure to phenanthrene, Cu, Cd, and Hg for 15 days in mussels. Concerning micronuclei, the evaluation of the total nuclear abnormalities, instead of the micronucleus only, as a biomarker of marine pollution, indicated more statistically significant differences between the control and the pollutant treated groups. Contrary to the existing knowledge showing that there is an increase in lipid content after pollutant exposure, our results showed that there was a decrease in the amount of lipid, as well as an increase in the number of neutral lipids. Furthermore, although prior studies found that fewer lysosomes formed after pollutant exposure, this was not confirmed by our work, as pollutant treated animals exhibited a decrease in the volume and an increase in the numerical density of lysosomes, compared to control groups.  相似文献   

封闭式组合膜结构的动力时程分析     

童丽萍  司瑞娟  曹延波 《世界地震工程》2006,22(4):110-115

由于索膜结构的变形具有明显的非线性,使得传统的谱分析计算会带来的较大的误差,利用ANSYS有限元程序,对封闭式组合膜结构进行了自振特性计算,并输E l Centro水平波进行了动力时程分析。结果表明,对于索膜结构,时程分析方比谱分析法更为可靠;索膜结构耦合现象明显,结构响应复杂,地震下的位移变化显著;所讨论的封闭式组合膜结构工程中,中部和两侧膜面区域的地震反应较大,起封闭作用的膜面在地震作用下性能良好。  相似文献   

结晶膜蒸馏处理吸收炼矿烟气酸性废水的研究     

王鹤  李滦宁  张凤君  张孝生  王顺义  沙娜  戴宁 《吉林大学学报(地球科学版)》2006,(Z1)

采用天然碳酸钙中和烟气吸收酸性废水,研究中空纤维结晶膜蒸馏技术对中和后废水处理的效果。考察了料液温度、起始浓度、流速、pH值等因素对膜通量的影响。在选定的条件下对水样进行连续膜蒸馏处理。结果表明,在料液温度50℃,料液速度为18.5mL/min,pH值为7,运行18h后,浓缩溶液开始出现结晶,结晶效果较好。截留率均接近100%。  相似文献   

高效液膜分离富集铜（Ⅱ）与测定微量铜   总被引：4，自引：0，他引：4  

王献科  李玉萍 《矿物岩石》1996,16(1):94-97

应用高效乱状液膜技术分离、富集水和土壤样品中微量铜。研究了流动载体（Ｐ２０４）、在面活性剂（Ｓｐａｎ８０）、膜的增强剂（液体石蜡）、膜溶剂（煤油）和内相解吸剂（２．５ｍｏｌ／ＬＨ２ＳＯ４）等液膜体系，对分离富集微量铜（Ⅱ）的影响。确定了Ｓｐａｎ８０－Ｐ２０４－液体石蜡－煤油－Ｈ２ＳＯ４高效液膜体系的最佳组成和最适宜的实验条件。富集后的溶液用１－（２－毗啶偶氮）－２一萘酚（ＰＡＮ）分光光度法测定铜（Ⅱ）。本法富集水和土壤中微量铜（Ⅱ），回收率在９９％以上。已成功地应用于测定水和土壤中的微量铜，相对标准偏差ＲＳＤ／％为１．２—４．５，结果十分满意。  相似文献   

黔西南地区卡林型、次生富集型金矿   总被引：3，自引：0，他引：3  

周茂基 《黄金地质》1996,2(4):15-20

黔西南地区卡林型金矿及与其相关的次生富集型金矿，是以海西期峨眉山玄武岩的边缘相火山碎屑岩为矿源层的再造矿床。与其相关的次生富集型金矿，是卡林型金矿或其矿源层的风化淋滤产物。碳酸盐岩与粘土岩的交界面及细粒碎屑岩中的糜棱岩等的半透膜渗析效应，在金矿成矿过程中起了重要的作用  相似文献   

以草酸钠为原料膜法制取草酸和烧碱的研究          下载免费PDF全文

郑竹林 《盐湖研究》1997,5(2):36-50

本文提供了一个用离子膜电解法生产草酸的新工艺，研究了草酸钠的提纯和制取草酸新方法的工艺条件，求取了技术经济指标，解决了传统工艺的三废污染和产品质低等问题。  相似文献   

岩土力学试验中的两个问题讨论及其应用     

张年学  周瑞光 《工程地质学报》1997,5(1):33-40

本文根据实验和理论分析, 提出一种单轴、三轴压缩试验的新的破坏判据, 分析其机理是体积或密度连续原则的破坏。指出这一判据有可能应用在这种试验的自动控制上。  相似文献