Surface Enhanced Raman Spectroscopy Using Silver Nanoparticles: The Effects of Particle Size and Halide Ions on Aggregation

A surface enhanced Raman spectroscopy (SERS) investigation of the aggregation of silver nanoparticles formed via LVCC with diameters in the range 5–50 nm were studied. It was found that with 647.1 nm excitation maximum enhancement is observed using particles with 11 nm diameters. Upon addition of sodium halides, enhancement is proportional to the polarizability of the anion. Maximum enhancement was observed when the concentration of the anion is approximately equal to the concentration of the adsorbate.     

气—固相置换法合成杂原子磷酸盐分子筛及其性能研究

用气—固相置换法合成SAPO—5,TAPO—5,BAPO—5分子筛。通过顺磁共振波谱,X射线光电子能谱,固体高分辨魔角核磁共振谱,红外酸性及晶胞参数等的测定多种研究方法,为杂原子Ti,Si,B进入分子筛骨架提供了证据。考察了分子筛的热稳定性,吸附性和晶体形貌。     

Activated decay pathways for planar vs twisted singlet phenylalkenes

The ground state conformation, spectroscopy, and photochemical behavior of styrene and eight of its vinyl- and ring-methylated derivatives have been investigated. Introduction of methyl groups at the alpha-position of the vinyl group or the ortho positions of the phenyl results in increased phenyl-vinyl dihedral angles. Styrenes possessing both alpha-methyl and ortho-methyl groups adopt orthogonal geometries. Decreased planarity results in a progressive blue-shift in the lowest energy allowed pi,pi transition and a decrease in the singlet lifetime. Kinetic modeling of the temperature-dependent singlet lifetimes provides activation parameters for the activated decay pathway, which is assigned to C=C torsion for styrenes with phenyl-vinyl dihedral angles, phi, < 60 degrees. Planar styrenes have large torsional barriers (7 +/- 1 kcal/mol) and decay predominantly via intersystem crossing and fluorescence at room temperature. Styrenes with values of 30 degrees < phi < 60 degrees have smaller torsional barriers and decay predominantly via C=C torsion at room temperature. Highly nonplanar styrenes decay predominantly via relatively rapid, weakly activated intersystem crossing.     

脂性油膏药物中黄芩甙含量的高效液相色谱分析

用0.02mol/L的三羟甲基胺基甲烷(用磷酸调pH值至7)和甲醇(含2%乙酸和0.25%庚烷磺酸钠)作流动相进行梯度洗脱,建立了脂性油膏药物中黄苓甙含量的反相高效液相色谱分析方法,本法分析速度快、重现性好，黄苓甙的平均回收率为103.7%.     

三配位硅正离子研究的新进展

本文综述了固相和液相中三配位硅正离子(R3Si^+)研究的最新进展, 讨论了硅上不同取代基, 阴离子及溶剂对硅正离子特征的影响。     

Surface characterization of polyimide films

 Various kinds of poly(amide acid)s were prepared by the reaction of four kinds of acid dianhydride and three kinds of diamine in N,N-dimethylacetamide (DMAc). Polyimide films were prepared by casting the poly(amide acid) solution on soda glass substrates, followed by thermal imidization at various temperatures. Contact angles of polyimide films for the sides in contact both with air and with glass substrate (air side and glass side, respectively) were measured to evaluate the dispersive component (γ^D _S) and the nondispersive component (γ^P _S) of surface free energy (γ_S) of polyimide films. It was shown that, for the air side, γ^P _S value decreased greatly and γ^D _S values increased slightly with the development of imidization. Values of γ^P _S for the glass side were much higher than those for the air side. Poly(amide acid) solution was also cast on quartz glass and silicone rubber, and was thermally imidized. The γ^P _S for the quartz glass side was almost the same as that for the soda glass side. But the γ^P _S for the silicone rubber side was as low as the γ^P _S for the air side. Attenuated total reflection infrared spectroscopy of polyimide films showed that the degree of imidization for the glass side surface was not as high as that for the air side surface, and that the amount of polar groups for the glass side surface was higher than that for the air side surface. Among the various kinds of polyimides, there is a slight but clear difference in the values of γ_S and its components, which can be rationalized from the difference in the chemical structure. It was also found that thermal degradation and oxidation can be easily detected from the change of surface free energy and its components for the polyimide films after being treated at high temperatures in both air and vacuo. Received: 22 January 1998 Accepted: 10 March 1998     

电场作用下离子型稀土矿浸矿溶浸液渗流特性研究

根据多孔介质中电动渗流效应,在离子型稀土矿浸出过程中,提出了利用电场强化浸矿溶浸液渗流能力的方法,通过机制分析和电动渗流试验,探讨了电场作用对溶浸液的渗流特性的影响。结果表明:电场作用可以有效地强化矿床孔隙中浸矿溶浸液渗流能力,强化效果与电场强度、矿床渗透率和溶浸液流体性质等因素有关;相同流体压力梯度下,电场作用下矿床中溶浸液电动渗流随电场强度增大而增加变快;矿床渗透率越高,电场作用对溶浸液渗流特性的影响越明显;浸矿溶浸液浓度越高,孔隙中溶浸液的电动渗流效应越明显。     

STUDIES ON STRUCTURE AND PHASE BEHAVIOR OF MULTICOMPONENT POLYMERS THROUGH RHEOLOGICAL TESTS

Rheological measurement has been a preferred approach to the characterization of the structure and phase behaviors for multi-component/multi-phase polymer systems, due to its sensitive response to the changes of structure for these heterogeneous polymers. In the present article, recent progresses in the studies on rheology for heterogeneous polymer systems including phase-separated polymeric blends and block copolymers are reviewed, mainly depending on the results by the authors＇ research group. By means of rheological measurements, not only some new fingerprints responsible for the evolution of morphology and structure concerning these polymer systems are obtained, also the corresponding results are significant for design and preparation of novel polymeric structural materials and functional materials.     

微酸性体系电沉积光亮锡钴锌合金的研究

本文提出了一种电沉积光亮锡钴镜三元合金的新工艺，其溶液组成及操作条件为：Ｎａ３Ｃ６Ｈ５Ｏ７．２Ｈ２Ｏ１００－１５０，Ｎａ２ＥＤＴＡ．２Ｈ２Ｏ２０－３０，ＳｎＣｌ２．２Ｈ２Ｏ１５－２０，ＣｏＳＯ４．７Ｈ２Ｏ２５－３５，ＺｎＣｌ２１５－２０ｇ．Ｌ＾－１；稳定剂ＷＤＺ－１ ６０－１００，光亮剂ＷＤＺ－２１５－２０ｍＬ．Ｌ＾－１，ｐＨ＝４－６，Ｄｋ＝０．５５。０Ａ．ｄｍ＾－２，Ｔ＝５－３５℃。在此条件下可     

高效液相色谱分离牛胸腺多肽的研究

本文以不同色谱方法对牛胸腺多肽进行了分离,寻求出能对牛胸腺多肽得到满意分离的色谱条件。