高能重离子辐照制备SiOC复合材料的研究

用120keV碳离子注入非晶SiO2薄膜,再用高能Xe、Pb和U离子辐照。注碳剂量范围为2.0×1017—8.6×1017 cm-2,高能离子辐照剂量1.0×1010—3.8×1012 cm-2。辐照后的样品用傅里叶变换红外光谱仪进行系统分析。实验结果显示,高能离子辐照在注碳非晶SiO2薄膜中形成了大量的Si-O-C键和Si-C键。这些Si-O-C结构具有环链、开链和笼链等多种结构形式。随电子能损、辐照剂量或者沉积能量密度的增加,SiOC结构由类笼向环/开链结构演化。对高能重离子驱动产生SiOC结构的机理进行了简单的讨论。

关于重丰中子远离核研究的实验方法

简单地介绍了重丰中子远离核研究的科学意义,报告了重丰中子新核素的产生、分离和鉴别方法。

~(125)Cs的能级结构

通过116Cd(14N,5n),Ebeam=65MeV的核反应布居了125Cs的高自旋态.利用在束γ谱学实验方法,进行了γ γ符合测量,使已知的125Cs核能级纲图得到了扩展,并且修正了某些组态的带头激发能.

What triggers the transition of palaeoenvironmental patterns in China；the Tibetan Plateau uplift or the Paratethys Sea retreat?

IEECAS SKLLQG

重离子治癌中磁扫描照射野形成法的初步参数要求

通过计算机模拟确定了磁扫描形成的照射野均匀度与束斑大小及扫描步长的关系 ;根据重离子治癌的逐片照射思想得到了束流强度计算式和照射时间关系式 ,并利用它们分别计算出了磁扫描的束流强度、最大扫描速度、最小束斑停留时间等技术参数。结果表明 :当扫描步长小于等于束斑半宽度时 ,磁扫描形成的照射野均匀度可达到好于 95 %的要求 ;磁扫描的适当束流强度为 0 .4 8nA ,最大扫描速度为 1 0 0 0cm/s ,最小束斑停留时间为 0 .2 4ms。

DNA和细胞对重离子辐照诱导DNA双链断裂的敏感性比较

用倒转脉冲场凝胶电泳 (PIGE)比较研究了 50 Me V/u1 2 C6 +辐照小鼠 B1 6黑色素瘤细胞及其脱蛋白 DNA分子 ,从而诱导 DNA双链断裂 (DSB)的辐射敏感性。结果表明 ,不论辐照脱蛋白 DNA还是辐照完整细胞 ,诱导的 DNA片段释放百分比 (PR)都随着剂量的增加而增加 ,在超过 4 0 Gy后 ,PR趋向一个近似相同的准阈值～ 81 %。辐照脱蛋白 DNA诱导的 DSB产额为 0 .4 0 DSBs/1 0 0 Mbp/Gy,辐照完整细胞诱导的 DSB产额约为 0 .1 9DSBs/1 0 0 Mbp/Gy。说明脱蛋白 DNA分子比完整细胞对重离子辐照要敏感

单核子在具有八极形变的平均势场中的混沌运动(Ⅱ)初始相干态空时演化中正则变量的期望值和测不准度的特征

研究了二维不对称谐振子的相干态在附加八极形变势作用下传播时，量子正则变量的期望值和测不准度的变化，发现量子混沌与相应的经典混沌完全对应地表现了多种性质．量子混沌的特征也与势能面的几何对称性，即势能面上负曲率的存在及负曲率的大小有关系．

不同石油污染区微生物修复技术研究

采集辽河油田不同石油污染地区的土样 ,经富集、驯化、分离、筛选 ,得到优势石油降解菌。它们分别是假单胞菌属、黄单胞菌属、黄杆菌属、节杆菌属、动胶杆菌属 ,这些菌既有普遍性 ,同时又不乏地域特色。经系统测定其生理特性及表面活性物质对其利用多环芳烃物质的影响 ,结果表明不同石油污染区土壤的理化特性与优势细菌的生理特性相关 ;表面活性剂Tween 80可使优势细菌降解菲的速率及程度均有提高。

Orientation and alignment of reagent molecules by two-photon excitation

The expressions used for describing the angular distribution of oriented and aligned reagent molecules are derived. The algebraic forms of orientation and alignment parameters of molecules in the excited states are obtained for two-photon excitation. The reagent molecules after absorbing two-photon may produce the higher order orientation and alignment than doing one-photon. (C) 2002 Elsevier Science B.V. All rights reserved.

Preparation and characterization of monolithic columns for capillary electrochromatography with weak electroosmotic flow

Monolithic columns of capillary electrochromatography (CEC) with weak electroosmotic flow (EOF) have been prepared by in situ polymerization of butyl methacrylate and ethylene dimethacrylate, without any charged groups in the reaction mixture. The reproducibility of such columns has been proved good no matter whether they are prepared in the same batch or in different batches. In the case of BMA-EDMA monoliths, besides the traditional ternary mixture - 1-propanol, 1,4-butanediol, and water, binary porogenic solvents with only alcohols have also been adopted. Compared with ternary porogenic solvents, the design with binary ones allows for fine control of the pore diameter and the formation of the specific surface of the monolithic polymers. The composition of porogenic reagents has also been shown to have an effect on EOF in the column systems. In addition, the Joule heat effect in such columns has been studied by varying the inner diameter of columns. Through the separation of acidic compounds, monolithic columns with low EOF have shown potential in the analysis of charged samples.

Influence of iron promoter on catalytic properties of Rh-Mn-Li/SiO2 for CO hydrogenation

The effect of iron promoter on the catalytic properties of Rh-Mn-Li/SiO2 catalyst in the synthesis Of C-2 oxygenates from syngas was investigated by means of the following techniques: CO hydrogenation reaction, temperature-programmed reduction (TPR), temperature-programmed desorption and reaction of adsorbed CO (CO-TPD and TPSR) and pulse adsorption of CO. The results showed that the addition of iron promoter could improve the activity of the catalysts. Unexpectedly, the yield of C-2 oxygenates increased greatly from 331.6 up to 457.5 g/(kg h) when 0.05% Fe was added into Rh-Mn-Li/SiO2 catalyst, while no change in the selectivity to C-2 oxygenates was observed. However, the activity and selectivity Of C-2 oxygenates were greatly decreased if the Fe amount exceeded 1.0%. The existence of a little iron decreased the reducibility of Rh precursor, while the reduction of Fe component itself became easier. CO uptake decreased with increasing the quantity of Fe addition. This phenomenon was further confirmed by CO-TPD results. The CO-TPD and TPSR results showed that only the strongly adsorbed CO could be hydrogenated, while the weakly adsorbed CO was desorbed. We propose that Fe is highly dispersed and in close contact with Rh and Mn; such arrangements were responsible for the high yield Of C-2 oxygenates. (C) 2002 Elsevier Science B.V. All rights reserved.