功能陶瓷现状与发展动向

本文重点论述了功能陶瓷材料，原料粉体、工艺与装备、元器件市场的现状及其发展趋势。指出了功能陶瓷在现代科技领域中具有重要意义及广阔的应用前景。     

Study of the composition effect of glass ceramic and silver on poly(vinyl butyral) thermal degradation with thermogravimetric analysis

The thermal degradation of poly(vinyl butyral) (PVB)/glass ceramic, PVB/Ag, and PVB/glass ceramic/Ag composites was investigated with thermogravimetric analysis in nitrogen and air. Thermogravimetric data revealed that the compositions of both inorganic materials in air could greatly influence the thermal degradation of PVB. The degradation reactions of PVB/ceramic and PVB/Ag composites began earlier and accelerated rapidly at lower temperatures. The overall degradation period was obviously shortened for the thermal degradation of PVB/Ag in air, whereas a longer time was required for the PVB/ceramic composite than for PVB. Moreover, dual effects of ceramic and Ag on the thermal degradation of PVB were observed for PVB/ceramic/Ag composites. In addition, the catalytic effects of ceramic and Ag on the degradation reaction of PVB in air were verified with a kinetic analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2142–2149, 2004     

Polydispersity effect on transient flow behavior of polystyrene solution

Summary The transient flow behavior of the binary blend of monodisperse polystyrene fractions is measured by a flow birefringence method. Both of the shear stress and first normal stress difference are obtained simultaneously in time by using a PMFB technique. The entanglements of the polymer chains significantly affect the rheological property of the binary blend in flow region. Especially, the entanglements of the high molecular weight fractions with themselves is proven to be the main source to the growth of first normal stress differences.     

Preparation and properties of (BATB–ODPA) polyimide–clay nanocomposite materials

A series of polymer–clay nanocomposite (PCN) materials consisting of 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene–4,4′‐oxydiphthalic anhydride (BATB–ODPA) polyimide (PI) and layered montmorillonite (MMT) clay were successfully prepared by an in situ polymerization reaction through thermal imidization up to 300°C. The synthesized PCN materials were subsequently characterized by Fourier‐Transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of material composition on thermal stability, mechanical strength, molecular permeability and optical clarity of bulk PI and PCN materials in the form of membranes were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), molecular permeability analysis (GPA) and ultraviolet‐visible (UV/VIS) transmission spectra, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1072–1079, 2004     

Field evaluation of chiral isomers of the sex pheromone of the european pine sawfly,Neodiprion sertifer

Among optical isomers of 3,7-dimethylpentadecan-2-ol (diprionol) acetate or propionate tested as synthetic attractants, the 2S, 3S, and 7S isomers were most effective in attracting the males ofNeodiprion sertifer in the field. The 2S, 3S, and 7R isomers showed weak activity, but the other optical isomers were not attractive. Capillary GC analysis showed that the natural pheromone from body extracts of females was identical with the synthetic acetate of diprionol in its GC behavior. However, the natural pheromone was about 100-fold stronger than the most purified synthetic acetate of 2S,3S,7S-diprionol in the field. As a result of various isomer combination studies, it was found that the acetate of 2S,3R,7R-diprionol, when added to 2S,3S,7S-diprionol preparation at a low concentration, increased the catch by the latter. It was therefore concluded that the above combination of the optical isomers could account for the major sex attractancy in this species.     

Enantio-differentiating hydrogenation of prochiral ketones over modified nickel

This article reviews the enantio-differentiating hydrogenation of prochiral ketones over a asymmetrically modified catalyst, focusing on the hydrogenation of simple prochiral alkanones. The parameters affecting catalytic activity and enantiodifferentiating ability are considerable in number, and each parameter should be optimized in order to attain a highperformance enantio-differentiating catalyst. Optimization of the parameters and the mode of enantio-differentiation are discussed and compared with the enantio-differentiating hydrogenation of β-ketoesters.     

EFFECT OF PORE DIFFUSION ON DEACTIVATING RATES OF SECOND ORDER REACTION

The research and development of catalysts, the design and operation of catalytic reactors are complicated by the phenomenon of catalyst deactivation which is affected by various factors. In this paper, the effect of internal mass transfer resistance in the second order catalytic reaction system of uniform independent deactivation on both reaction and deactivation rates of straight cylindrical pore model has been discussed. In addition, the quantitative relations between effectiveness factor and Thiele modulus in second order reaction and first order deactivation system have been correlated     

输出窗材料的研究进展

输出窗是高真空微波管中的关键构件,本文对目前应用的各种输出窗材料的性能、制备以及应用现状进行了评述。针对大功率毫米波微波管用输出窗材料的需求,提出了制备输出窗复相陶瓷以及创新制备方法等解决思路。     

组分对发射盐物相、浸渍温度和稳定性的研究

311、411、612、2.4：0．6：1是常用的阴极钪酸盐（Ba：Ca：Al2摩尔比，分别添加微量Sc2O3）配比。相同工艺条件，4种配比钪酸盐的衍射峰区别不大；相同温度条件，2．4：0．6：1的阴极钪酸盐对纯钨基的浸渍度最高，达到99．34％；同时24：0．6：1的阴极钪酸盐在空气中的稳定性也是最好的。     

A randomized algorithm for natural object colorization

Natural objects often contain vivid color distribution with wide variety of colors. Conventional colorization techniques, on the other hand, produce colors that are relatively flat with little color variation. In this paper, we introduce a randomized algorithm which considers not only the value of target color but also the distribution of target color. In essence, our algorithm paints a color distribution to a region which synthesizes color distribution of a natural object. Our approach models the correlation between intensity and color in HSV color space in terms of H – S, H – V and S – V joint histogram. During the colorization process, we randomly swap and reassign color of a pixel to minimize a cost function that measures color consistency to its neighborhood and intensity‐to‐color correlation captured in the joint histogram. We tested our algorithm extensively on many natural objects and our user study confirms that our results are more vivid and natural compared to results from previous techniques.