低密度聚乙烯光引发交联机理——Ⅱ.BNB自旋捕捉ESR研究

在光引发剂二苯甲酮(BP)存在下,紫外光辐照低密度聚乙烯(LDPE)所形成的自由基中间体已被自旋捕捉剂2,4,6-三特丁基亚硝基苯(BNB)所捕捉,其自旋加合物自由基已为电子自旋共振(ESR)所特征。现已检测和鉴定到二种自旋加合物:一种是叔碳自由基;另一种是仲碳自由基。它们分别是由BP的激发三重态从LDPE链的支化点和亚甲基团上夺氢所形成的自由基中间体同自旋捕捉剂BNB反应生成的。上述的证据表明:LDPE的光引发交联点主要发生在叔碳和仲碳原子上,且H-型交联点占主导地位。     

三氟化硼修饰载体负载茂金属催化乙烯聚合

用BF3对载体硅胶和氧化铝进行了表面修饰,考察了修饰的载体负载茂金属催化剂后催化乙烯聚合的特性.研究表明,用BF3修饰过的载体负载二氯二茂锆催化乙烯的聚合,聚合活性有较大提高,具有工业应用前景,并且提出了这一催化体系的负载机理.     

四烷基锡中性载体推动亚硝酸根离子迁移穿透大块液膜

通过大块液膜体系研究了四烷基锡的碳链长度、载体浓度.NO_2~-浓度及抗衡离子等因素对NO_2~_穿透含四烷基锡的液膜的传质速率的影响,讨论了它们与四烷基锡为载体的离子电极性能间的关系。NO_2~-通过四烷基锡为载体的液膜的迁移规律符合离子对传输模式。     

中性载体阳离子电极膜电化学的计算机数字模拟

对中性载体阳离子电极膜3种可能的传输模式进行了数字模拟,研究了淌度、浓度、配合物稳定常数以及阴离子亲脂性对电极电位响应的影响。模拟结果对于廓清这类电极响应机理,解释有关实验现象及指导新电极设计提供了有用的信息。     

Enhancement of electronic excitation energy transfer in the colloidal crystals of colloidal silica suspensions doped with fluorescent dyes

The efficiency of electronic excitation energy transfer from photo-excited rhodamine 110 (Rh110, energy donor) to rhodamine B (RhB, energy acceptor) in an exhaustively deionized colloidal silica suspension has been studied. This colloidal suspension shows Bragg reflection due to the formation of colloidal crystals and the Bragg-peak wavelength is controllable by the volume fraction of the silica spheres. When the Bragg-peak wavelength matches with the fluorescence band of Rh110, a depletion was observed in the Rh110 fluorescence spectrum. This means the fluorescence of Rh110 is partially trapped due to the Bragg reflection inside the crystal lattice. In the coexistence of RhB, the enhancement of RhB fluorescence intensity was observed. These facts clearly indicate the trapped photon energy of Rh110 is efficiently transferred to RhB within the colloidal crystals. The quantitative measurements showed that the enhancement of the transfer efficiency is 20% (or slightly more) in the present experimental conditions.     

一种新型铒镱共掺碲硅酸盐玻璃的光谱性质及荧光俘获效应研究

用高温熔制法制备了系列Er^3＋／Yb^3＋共掺碲硅酸盐玻璃样品，测试和分析了玻璃样品的吸收光谱、荧光光谱、上转换发光光谱及热稳定性。结果表明：这种玻璃具有较宽的荧光半高宽、较大的受激发射截面，较好的热稳定性。970nm泵浦下该系列玻璃在可见光525，546和658nm这3处存在明显的上转换现象，它们分别由Er^3＋离子^2H11/2→^4 I15/2，4S3/2→^4 I15/2和^4 F9/2→^4 I15/2辐射跃迁产生。另外，测试和讨论了在不同样品厚度下玻璃的光谱特性，如荧光光谱、荧光寿命和上转换发光光谱等。结果表明，荧光俘获效应对Er^3＋离子1．5μm波段荧光及上转换发光都有着较大的影响，并随着玻璃厚度的增加而增大，导致测量值与实际值产生较大的偏差。     

Thermodynamic and Equilibrium Composition Analysis of Using Iron Oxide as an Oxygen Carrier in Nonflame Combustion Technology

1. Introduction The utilization of fossil fuels causes serious neg- ative impacts on the environment and human life. There are many pollutants such as SOx, NOx and CO2 emission produced from the combustion of coal, oil and natural gas. It has been known for more than 100 years that CO2 is a greenhouse gas and that the release of CO2 from fossil fuel combustion may affect the climate of the earth. In the last years the concern over the aspects of an increased release of greenhouse gases has…     

Optimum gas chromatographic conditions in wall-coated capillary columns. Extended and simplified forms of the Golay-equation

Band broadening in capillary columns is satisfactorily described by the Golay-equation extended to situations of appreciable pressure drop by Giddings. In practice, however, several simplifications are often made. The effect of these simplifications on the calculated values of the minimum plate height and optimum carrier gas velocity are treated systematically.