Synthesis and characterization of a positive‐working,aqueous‐base‐developable photosensitive polyimide precursor

A positive‐working, aqueous‐base‐developable photosensitive polyimide precursor based on poly(amic ester)‐bearing phenolic hydroxyl groups and a diazonaphthoquinone photosensitive compound was developed. The poly(amic ester) was prepared from a direct polymerization of 2,2′‐bis‐(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and bis(n‐butyl)ester of pyromellitic acid in the presence of phenylphosphonic dichloride as an activator. Subsequently, the thermal imidization of the poly(amic ester) precursor at 300°C produced the corresponding polyimide. The inherent viscosity of the precursor polymer was 0.23 dL/g. The cyclized polyimide showed a glass‐transition temperature at 356°C and a 5% weight loss at 474°C in nitrogen. The structures of the precursor polymer and the fully cyclized polymer were characterized by Fourier transform infrared spectroscopy and ¹H‐NMR. The photosensitive polyimide precursor containing 25 wt % diazonaphthoquinone photoactive compound showed a sensitivity of 150 mJ/cm² and a contrast of 1.65 in a 3 μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 10 μm was obtained from this composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 352–358, 2002     

Continuous ethanol production from wood hydrolysate by chemostat and total cell retention culture

Chemostat and total cell retention cultures with internal filter system ofSaecharomyc.es cerevisiae H1-7 were carried out to produce ethanol from wood hydrolysate. Maximum ethanol productivity obtained in a chemostat with the aeration rate of 1 vvm was 3.79 g/(L·h). This was 20% higher than that in a chemostat without aeration. However, the substrate was not completely consumed at the dilution rate with the maximum productivity. The realistic productivity, which has higher than 99% conversion rate of substrate, was. 2.95 g/(L·h). The maximum productivity in the total cell retention culture was 6.65 g/(L·h) at the dilution rate of 0.19 h¹ and the residual glucose concentration was negligible.     

真实图像转换的水墨图像绘制模拟

目的：中国水墨风格模拟是非真实感图像模拟的重要研究课题,现有的模拟算法对于边缘绘制的连贯性不足、颜色汇聚不平滑,导致效果生硬、色彩表现力不强。为此本文提出一种真实图像转换的方法来对图像进行水墨风格化处理。方法：首先利用改进的基于流的高斯差分滤波来生成边缘轮廓;接着运用了各向异性Kuwahara滤波实现了墨色的汇聚以及自然过渡;最后引入Perlin噪声模拟背景宣纸的褶皱感。结果：实验表明,本文方法能够实现真实图像输入到水墨画风格图像输出的转换,处理速度快。结论：本文提出一种真实图像转换的水墨图像风格化处理方法,实验结果表明,该方法可以在不破坏原图像结构的基础上获得很好的水墨模拟效果。     

创新型嵌入式实验教学模式研究

结合军校计算机专业人才培养的具体需求,深入阐述了嵌入式计算机实验教学模式面临的问题,分析了当前军队院校实验教学现状及存在的不足,提出了嵌入式计算机实验教学的改革措施和原则,最后给出了发展创新型实验教学模式的思路。     

基于重要边缘点的时间序列异常模式检测算法

在分析边缘算子的思想和现有时间序列模式表示方法基础上,将边缘点方法和重要点方法相结合,提出了基于重要边缘点的时间序列模式表示算法。算法按各观测点的边缘化程度,提取重要的边缘点将时间序列分成多个子线段,通过分析直线段之间的相似性,发现异常的序列模式。从理论和实验两方面对算法进行了分析和验证,结果表明,算法复杂度较低,模式表示误差小,能够满足大规模时间序列数据模式表示的要求。     

Protoporphyrin-modified gold surfaces for the selective monitoring of catecholamines

Protoporphyrin IX (PPIX) was immobilized on Au surfaces for the electrochemical oxidation of dopamine (DA) and epinephrine (EP). Two procedures for the immobilization were employed. One class of modified electrodes was prepared by immobilizing the PPIX into polypyrrole (PPy) films synthesized by anodic electropolymerization. The other procedure involved the immobilization of PPIX on an electrode modified by a 11-mercaptoundecanoic acid (MUA) self-assembled monolayer (SAM). The modified surfaces were characterized by cyclic voltammetry (CV).The efficiency of these modified surfaces for the electrochemical oxidation of DA and EP was investigated and compared. The peak potential for the oxidation of each analyte at the different electrode surfaces was determined by square-wave voltammetry (SWV).The dependence of the sensitivity of the electrodes for the detection of the catecholamines on the applied potential was also measured. The SAM-based electrodes showed better selectivity for detecting DA in the potential range between 0.2 and 0.4 V versus Pt (QRE). However, higher sensitivity and linearity were observed for the film-based electrodes.     

铸铝合金在有机羧酸体系中电化学陶瓷成膜

利用电化学沉积陶瓷膜（EDCF）技术将铸铝ZL108合金置于有机羧酸复合体系，制得了具有较高硬度和良好外观的灰色类陶瓷膜。详细研究了各工艺参数对膜层性能的影响，结果表明，有机羧酸是主要成膜物质；金属硫酸盐是阳极反应的活化剂，但浓度过高会加快膜层溶解；方波脉冲电源有利于生成厚膜；峰值电流密度越大，成膜时间越短，但过大会使膜层减薄；溶液pH值、搅拌等对成膜过程有一定影响。     

Adhesion properties of UV crosslinked polystyrene-block-polybutadiene-block-polystyrene copolymer and tackifier mixture

The peel and tack properties of mixtures of polystyrene-block-polybutadiene-block-polystyrene (SBS) and a tackifier were investigated after these were crosslinked by ultraviolet (UV) irradiation at various amounts of benzophenone (BP) as a photoinitiator and trimethylolpropane mercaptopropionate (TRIS) as a crosslinking agent.The degree of crosslinking of polybutadiene (PB) block in the SBS mixture was qualitatively estimated from the amount of gel fraction as well as the change in the glass transition temperature of the PB block. The crosslinking of the PB block was done within 3 min after UV irradiation and the peel strength of crosslinked specimens was as low as 45[percnt] of specimens without crosslinking. Nano-tack and bulk tack properties as well as the surface tension of mixtures were measured depending upon amounts of BP and TRIS.     

红外吸收法测硅铁中的超低硫

应用高频红外碳硫仪,建立了硅铁合金中超低硫测定方法,对选择适当的测定条件如助熔剂、分析时间等进行了探讨,最佳测定条件:最大工作电流为400～480 mA;载气纯度为99.99%;陶瓷坩埚需经1 100℃灼烧2 h后,可使空白降至最小;硫元素最短分析时间为40 s,比较水平为5.00.