钯/铁双金属对土壤中2,2′,3,4,4′,5,5′-七氯联苯的催化脱氯研究

采用Fe0还原、钯催化法对土壤中2,2′,3,4,4′,5,5′-七氯联苯的的还原特性进行了实验研究.结果表明,Pd/Fe双金属能有效地进行2,2′,3,4,4′,5,5′-七氯联苯的催化脱氯.在钯化率为0.05%、钯/铁加入量1 g、初始pH为5.6、反应时间5 d的条件下,钯/铁双金属对土壤中2,2′,3,4,4′,5,5′-七氯联苯去除率达54%.实验还考察了钯化率、初始pH、反应时间、钯/铁投加量、2,2′,3,4,4′,5,5′-七氯联苯初始浓度等参数对2,2′,3,4,4′,5,5′-七氯联苯脱氯效果的影响.研究表明,较高的钯化率、钯/铁加入量,较低的2,2′,3,4,4′,5,5′-七氯联苯初始浓度及弱酸性等条件更有利于Pd/Fe对2,2′,3,4,4′,5,5′-七氯联苯的还原脱氯.在Pd/Fe双金属表面,2,2′,3,4,4′,5,5′-七氯联苯的脱氯符合一级动力学反应,反应速率常数为0.014 2/h,其半衰期为49 h.利用实验数据,对钯/铁双金属作用下的2,2′,3,4,4′,5,5′-七氯联苯还原脱氯的反应机制也进行了分析.

偏最小二乘回归方法在土地利用结构研究中的应用

针对当前LUCC研究中存在的数据间多重相关性和样本量不足的问题,论文将一种新型的多元统计数据分析方法———偏最小二乘回归引入到研究中。该方法可以有效地克服上述缺陷,并能实现多种数据分析方法的综合应用。为检验方法的功能及实用性,论文以苏锡常地区为例,对区域的土地利用结构及其影响因子进行了定量分析。结果表明,偏最小二乘回归是进行土地利用结构研究的一种十分有效的工具,在地学领域有广阔的应用前景。

Multi-armed poly(L-glutamic acid)-graft-oligoethylenimine copolymers as efficient nonviral gene delivery vectors

Background The application of polyethylenimine (PEI) in gene delivery has been severely limited by significant cytotoxicity that results from a nondegradable methylene backbone and high cationic charge density. It is therefore necessary to develop novel biodegradable PEI derivates for low-toxic, highly efficient gene delivery.Methods A series of novel cationic copolymers with various charge density were designed and synthesized by grafting different kinds of oligoethylenimine (OEI) onto a determinate multi-armed poly(L-glutamic acid) backbone. The molecular structures of multi-armed poly(L-glutamic acid)-graft-OEI (MP-g-OEI) copolymers were characterized using nuclear magnetic resonance, viscosimetry and gel permeation chromatography. Moreover, the MP-g-OEI/DNA complexes were measured by a gel retardation assay, dynamic light scattering and atomic force microscopy to determine DNA binding ability, particle size, zeta potential, complex formation and shape, respectively. MP-g-OEI copolymers were also evaluated in Chinese hamster ovary and human embryonic kidney-293 cells for their cytotoxicity and transfection efficiency.

窝雏数处理对两种雀形目幼鸟生长的影响

基于1997～1999年野外实验，对高寒草甸小云雀和黄嘴朱顶雀两种雀形目鸟的窝雏数进行增减处理。结果表明，对照组的幼鸟生长率和离巢体重都大于增加组，说明窝雏数增加后，幼鸟质量下降。随着窝雏数增加，这两种幼鸟生长率显著下降（小云雀：r = -0.965, P = 0.035 < 0.05；朱顶雀：r = -0.828, P = 0.022 < 0.05）。窝雏数改变对小云雀幼鸟出飞重影响不显著（r = -0.418, P = 0.528 > 0.05），而对黄嘴朱顶雀有显著的影响（r = -0.901，P = 0.014 < 0.05）。

陕南铜石铜矿黄铁矿的热电系数地球化学研究

通过对铜厂矿区黄铁热电系数研究，提出可以根据黄铁矿热电系数指导该区铜矿的寻找和评价，即黄铁矿热电系数为较大负值、导电型为Ｎ型导电的是铜矿赋存地段；而黄铁矿导电型为较小负值、导电型为Ｎ型或以Ｎ型导电为主的是铜矿化有利地段；黄铁矿热电系数为较高正值、其导电型为Ｐ型或以Ｐ导电为主的地段一般没有矿化。