氧化钡促进的Co/SiO2催化剂的还原性能和分解甲烷活性

 利用等体积浸渍法制备了氧化硅负载钴催化剂．通过程序升温还原、氢化学吸附、氧滴定和催化活性评价等手段研究了氧化钡对Co／SiO2的还原性能、钴分散度和颗粒度、分解甲烷活性及其稳定性等的影响．研究结果表明，氧化钡明显地影响Co／SiO2的还原性能；添加2％氧化钡提高了Co／SiO2在中温（450℃）条件下的还原度；氧化钡的还原对Co／SiO2还原的诱导、氧化钡与氧化硅及与氧化钴之间的相互作用是导致Co／SiO2还原性能变化的原因．氧化钡提高了Co／SiO2的初活性和钴的分散度，降低了钴的颗粒度；添加0．5％～1．5％氧化钡有利于提高Co／SiO2的稳定性．钴的分散度和颗粒度影响Co／SiO2的活性和稳定性；氧化钡的强供电效应也是提高Co／SiO2活性和稳定性的重要因素．甲烷分解生成的碳物种覆盖了钴活性中心，导致Co／SiO2初活性下降；但大部分碳物种并不沉积在钴活性中心上，可能形成了碳纤维生长在载体和钴活性中心之间．     

THE ''Q-BAND'' ABSORPTION spECTRA OF HEMATOPORPHYRIN MONOMER AND AGGREGATE IN AQUEOUS SOLUTION

Abstract The resolution of the absorption spectra in the Q band (480 nm-620 nm) spectral region of monomeric and dimeric hematoporphyrin species present in aqueous solutions has been achieved using absorption, fluorescence and computer analysis methods. The absorption maxima of the dimer in this spectral region are red shifted about 12 nm with respect to those of the monomer. The significance of this finding in relationship to the well documented blue shift of hematoporphyrin aggregate observed in the Soret band region (λ_malx∼400 nm) of the absorption spectrum is discussed.     

乙二醛诱导细胞凋亡的近红外表面增强拉曼光谱

将60 nm金纳米粒子导入到活的人骨肉瘤细胞中, 用近红外表面增强拉曼散射(SERS)技术获取细胞内化学成分的高分辨SERS信息. 对正常活性细胞和乙二醛诱导的凋亡细胞的比较研究表明, 对于正常活性的细胞, 金纳米探针主要分布在细胞质内(围绕细胞核), 而凋亡细胞内的金纳米探针的分布较为均匀, 在遍布凋亡细胞内的各个位置包括细胞表面均容易找到DNA片段的信息.     

The Influence of Variable Convective Velocities on Longitudinal Diffusion

Solutions are presented for the impulsively started uniformstream and simple shear flows past a point source of momentum,which can be interpreted to describe the position and the widthof the front which transmits the knowledge of the singularitythrough a slightly viscous fluid. These understandings are thengeneralized to show that the front always moves with velocityslower than that of a (strictly monotonic) convective velocity,and also that its width always grows faster than with simplediffusion. Finally, a remarkably simple, exact expression is given forvorticity due to a simple shear flow past a point vortex.