表面活性剂对纤维素接枝共聚物溶液粘度性质的影响

研究了阴离子十二烷基硫酸钠(SDS)、阳离子十六烷基三甲基溴化铵(CTAB)和非离子聚乙二醇辛基苯基醚(OP)等三种不同类型的表面活性剂对疏水化水溶性两性纤维素接枝共聚物(CGAO)溶液粘度性质的影响.结果表明,在SDS和OP的临界胶束浓度(cmc)附近，CGAO溶液粘度最大，SDS引起CGAO粘度的变化大于OP；即使在CTAB的cmc附近，随着CTAB浓度的增加，CGAO的粘度一直呈下降趋势；非疏水改性的纤维素接枝共聚物的溶液粘度随SDS或CTAB浓度的增加而下降，但几乎不随OP浓度的增大而变化.此外，通过凝胶渗透色谱法测得的保留时间证实了SDS、CTAB和OP与CGAO之间的疏水缔合作用.     

Resonance Rayleigh scattering technology as a new method for the determination of the inclusion constant of beta-cyclodextrin

The interaction of procaine hydrochloride and beta-cyclodextrin in aqueous solution was studied using resonance Rayleigh scattering technology. The molar ratio of the inclusion complex was 1:1 established by spectrophotometry. The resonance Rayleigh scattering technology was first applied in the determination of the beta-cyclodextrin inclusion constant. The inclusion constant of procaine hydrochloride beta-cyclodextrin complex Kf is 1.23 x 10(2) and 1.27 x 10(2) l mol(-1) for method I and 1.15 x 10(2) and 1.21 x 10(2) l mol(-1) for method II. These determination results were in correspondence with the results of the spectrophotometric and fluorescence methods. Therefore, the resonance Rayleigh scattering method can be used as a new technology for the determination of the inclusion constant.     

Dielectric properties and frequency response of self-assembled monolayers of alkanethiols

This paper presents dielectric properties of alkanethiol self-assembled monolayers (SAMs) under an ac electric field. Using a Hg-SAM/SAM-Hg junction, we measured the ac impedance of alkanethiol SAMs using a sinusoidal perturbation of 30 mV (peak-to-peak) with frequency ranging from 1 Hz to 1 MHz at zero bias. Semicircles at higher frequencies and at middle frequencies along with Warburg lines at lower frequencies were observed in complex plane impedance plots, that is, Nyquist plots. The frequency response of SAMs was analyzed by modeling the junction using an equivalent circuit and fitting the Nyquist plots. The semicircles at higher frequencies are attributed to the effect of the SAM/SAM interfaces, and the ones at middle frequencies are attributed to the effect of alkanethiol SAMs. The comparison in the plots of the imaginary part of the impedance Z against frequency for the bare Hg electrodes (in pure ethanal) and the SAM-covered Hg electrodes (in alkanethiol solution) supports the analysis. The Warburg lines are attributed to a certain ionic impurity. The dielectric loss spectra are further analyzed. Chain-length-dependent peaks, which correspond to different relaxation mechanisms, at higher frequencies and middle frequencies were observed in the spectra of the dissipation factor (tan delta vs frequency). The peaks move to small frequency with the increase of chain length of alkanethiols. Using a correlation of peak position with the chain length, we then derived active energies of 39-99 meV for alkanethiol SAMs of C7-C18 under an ac electric field.     

Electrodeposition of nanocrystalline zinc from acidic sulfate solutions containing thiourea and benzalacetone as additives

Nanocrystalline zinc coatings were produced by pulse electrodeposition in acid sulfate bath containing thiourea and benzalacetone additives and characterized by X-ray diffraction and scanning electron microscopy techniques. The influence of benzalacetone concentration and pulse peak current density on the grain size and crystallographic orientation of zinc deposits was investigated. Zinc electrodeposited from additive-free solutions or with one of the two additives is not composed of nanosized crystals. The mixture additives of thiourea and benzalacetone give rise to the formation of particle-like nanocrystalline zinc with a (10ī1) random orientation. A change in peak current density from 2 to 1 A/cm² only increases the grain size from 60 to 62 nm.     

Polystyrene-supported recyclable palladacycle catalyst for Heck, Suzuki and Sonogashira reactions

A new type of soluble polystyrene-supported palladium complex as an excellent and recyclable palladacycle catalyst was discovered for carboncarbon bond formation in Heck, Suzuki and Sonogashira reactions. Precipitation and filtration process for recycling the catalyst was also achieved.     

2,2—二（4—甲氧基苯基）—1,1—二氯乙烯的显色反应及应用研究

本文对2,2-二(4-甲氧基苯基)-1,1-二氯乙烯(简称DMDE)与H_2SO_4显色反应的机理进行了探讨,证实了该反应为可逆反应,其显色产物与亲电加成反应的中间体有关;并利用该反应建立了甲氧基氯原药和乳油中DMDE含量的分光光度测定方法。实验表明:DMDE在0～27.5μg/10ml范围内服从比耳定律,其表观摩尔吸光系数ε为2.56×10~4L·mol~(-1)·cm~(-1)。应用该法对甲氧基氯原药和乳油进行了分析,获得满意结果。     

新型糠醛加氢制糠醇催化剂研究

新型糠醛加氢制糠醇催化剂研究林培滋，黄世煜，周焕文，赵彤彤，刘崇早，罗洪原，梁东白（中国科学院大连化学物理研究所，大连１１６０２３）关键词铜催化剂，糠醛，加氢，糠醇糠醇是重要的化工原料，糖醇树脂是耐酸、碱腐蚀的材料，在工业发达的国家中，铸造工业广泛采...     

聚丙烯腈高分子半导体纤维的研究——聚丙烯腈高分子半导纤维的制备及其半导体特性

经四氯化锡处理的聚丙烯腈纤维,在进一步热处理过程中可以成为一种高分子半导纤维。它具有如下四个特点:1.纤维电阻率在10~3—10~(12)欧姆·厘米范围内可以控制热处理温度而随意调节。2.水解处理干燥后纤维的电阻值基本不变。3.有足够的机械强度可以进行多种形式的加工。4.纤维的电阻-温度、电导率-频率依赖关系,直流伏-安特性的试验结果表明它具有有机半导体特性,是一种兼有良好电性能和力学性能的高分子半导纤维。     

铟(Ⅲ)-7-(1-苯偶氮)-8-羟基喹啉-5-磺酸钠的配位吸附波及其应用

在ｐＨ４．５的 ０．０１５ ｍｏｌ／Ｌ ＨＡｃ－ＮａＡｃ介质中，Ｉｎ铟（Ⅲ）－７－（１－苯偶氮）－８－羟基喹啉－５－磺酸钠（ＢＱ）在滴汞电极上于－０．６６５－０．７０ Ｖ（ｖｓ．ＳＣＥ）电位处得到络合物的吸附还原波，其一阶导数峰电流Ｉ＇ｐ与Ｉｎ（Ⅲ）浓度在４．０× １０~（－８）～３．５ × １０~（－６）ｍｏｌ／Ｌ范围内呈良好的线性关系，检测限为１．６ × １０~（－８）ｍｏｌ／Ｌ Ｉｎ（Ⅲ）．应用该法测定了铅粉和氢氧化铝样品中的微量铟，结果令人满意。对电极反应机理进行了探讨。