新型磺化聚酰亚胺膜的合成与表征

合成了4,4’-二(间氨基苯氧基)联苯-3,3’-二磺酸(mBAPBDS)单体, 采用红外光谱和核磁共振等方法对其结构进行了表征. 使用mBAPBDS, 2-(对胺基苯基)苯并噁唑-5-胺(APBA)和1,4,5,8-萘四甲酸二酐(NTDA)共聚合成了含有噁唑结构的新型磺化聚酰亚胺(NTDA-mBAPBDS/APBA), 通过控制磺化二胺与非磺化二胺的比例来控制磺化程度. NTDA-mBAPBDS/APBA共聚物表现出较好的溶解性、成膜性能和良好的热稳定性, 其磺酸基团分解温度高于300 ℃. 采用溶液浇铸法制备了磺化聚酰亚胺(SPIs)膜, 对膜的吸水率、溶胀度和质子电导率等性能进行了初步的研究. 结果表明, SPIs膜具有适当的吸水率和良好的尺寸稳定性, 其室温电导率在4.72×10－3和9.60×10－3 S/cm之间, 接近于相同条件下Nafion®117的电导率(9.80×10－3 S/cm).     

High energy heavy ion tracks in bubble detectors

Bubble detectors which are commonly used as neutron detectors have been demonstrated through this study to be good detectors for registration of high energy heavy ion tracks. Large size bubble detectors made in China Institute of Atomic Energy were irradiated to heavy ions Ar and C up to 650 MeV/u and 400 MeV/u, respectively. Very clear features of stringy tracks of high energy heavy ions and their fragmentations are manifested and distinguishable. A single track created by a specific high energy heavy ion is composed of a line of bubbles, which is visible by naked eyes and retained for months wihhout reduction in size. The creation of heavy ion tracks in bubble detectors is governed by a threshold whose essence is approximately a critical value of energy loss rate (dE/dX)_c similar to that of etch track detectors. Ranges of heavy ions in bubble detectors are apparent and predictable by existing formulas. Identification of high energy heavy ions and the applications to heavy ion physics, cosmic rays, exotic particles and cancer therapy monitoring are obviously promising. The experimental and theoretical aspects of high energy heavy ion tracks in bubble detectors as well as the expectable applications are presented and discussed.     

用于递模塑料的有机硅树脂

本文指出提高水解温度,或使用丙酮和甲苯混合溶剂,有利于甲基三氟硅烷与苯基三氯硅烷和二甲基二氯硅烷的共水解缩聚反应,而不易产生凝胶现象。并以此合成了适于递模塑料的R/Si较小、C_6H_5/R较低、羟基含量较高的羟基缩合型无溶剂树脂,简化了步骤,大大缩短了操作时间,树脂质量稳定。此外还讨论了树脂的结构与递模塑料性能的关系,选择了较好的固化剂以及通用的补强剂,使塑料具有优异的性能。     

Mesoscale constitutive modeling of magnetic dispersions: material functions for shear flows

We recently developed a constitutive model for magnetic dispersions by modeling the magnetic particles as rigid dumbbells dispersed in a solvent. The theory yielded a constitutive equation in which the stress tensor could be expressed as a function of the velocity gradient, an orientational order tensor, S, an average alignment vector, J, and any imposed external magnetic field, H. The constitutive equation is used here to predict material functions for steady shear flow (shear-rate dependent viscosity and first normal stress coefficient) as well as those for unsteady shear flows (stress growth upon inception of steady shear and small-amplitude oscillatory shear). The importance of effects of concentration, equilibrium nematic ordering in the dispersion, and anisotropy in the hydrodynamic drag are emphasized. Comparisons with available experimental data on viscosity for magnetic inks under steady shear flow and inception of steady shear flow show reasonably good agreement.     

Catalytic asymmetric hydrogenation in a room temperature ionic liquid using chiral Rh-complex of ionic liquid grafted 1,4-bisphosphine ligand

Introduction of imidazolium ionic liquid pattern to the catalyst not only avoided catalyst leaching but also increased the stability of catalyst in ionic liquid, and thus, the Rh-complex of 1,4-bisphosphine bearing two imidazolium salt moieties was successfully immobilized in an ionic liquid and reused several times for the hydrogenation of an enamide without significant loss of catalytic efficiency.     

Understanding delamination in microelectronic devices using AES,XPS and chemometrics

The recent development of XPS instrumentation with near‐micron spatial resolution has advanced the capability of elemental and chemical‐state imaging accompanied by small‐area analysis (down to 15 µm). In this paper, the combined use of X‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) at enhanced spatial resolution is shown to have significantly improved the understanding of interfacial delamination and related problems encountered in the production of electronic devices in the field of microelectronics. An example of the application of surface analysis for ITO/Mo adhesion problems will be presented. The mathematical procedure using principal component analysis (PCA) in the reduction of noise in XPS images will also be described. The dramatic improvements in the image contrast and chemical component determination from multispectral image data sets will be presented. This study is intended to explore the contributions given by advanced surface analysis tools to solve real‐world problems. Copyright © 2007 John Wiley & Sons, Ltd.     

电感耦合等离子体原子发射光谱分析中导数光谱法研究——Ⅱ.数据平滑和扫描步长的影响

数据平滑和扫描步长是两个重要求导条件。本工作用五点三次多项式平滑技术对扫描数据进行平滑处理以消除随机噪音,但平滑次数增大会导致信号失真从而使导数光谱的分辨能力降低。扫描步长减小能提高导数光谱的分辨能力,但同时导致导数光谱灵敏度减小。导数光谱中干扰物等效浓度IEC的大小是上述因素的综合反映。本文以IEC为考察指标,讨论了平滑次数和扫描步长的优化。     

含5-氟脲嘧啶的聚硅氧烷的合成

5-氟脲嘧啶与α、ω双二乙胺基聚二取代基硅氧烷反应 可得含5-氟脲嘧啶的缩聚物。并以红外、核磁对缩聚物进行了研究。在室温将所得缩聚物在不同pH介质中,进行水解,以266.5nm处紫外吸收光度,定量测定所释放出来5-氟脲嘧啶。当缩聚物n值增大时,水解速度减慢,1、3结构则比2、4结构缩聚物为快。     

Synthesis and liquid crystalline properties of T-shaped dimesogenic compounds

Two series of new dimesogenic liquid crystalline compounds were synthesized and their LC and other thermal properties were characterized. These compounds consist of two mesogenic units connected through polymethylene spacer of varying length in the shape of the letter ‘T’. The difference between the two series is in the structure of tail groups attached on the pendant azobenzene mesogens; one of which is n-butyl and the other is phenyl. The compounds were characterized for their liquid crystallinity by the differential scanning calorimetry (DSC), X-ray diffractometry and visual observation of the melts on a hot-stage attached to a polarizing microscope. All these compounds were found to form only the nematic phase enantiotropically.