Novel blood-compatible waterborne polyurethane using chitosan as an extender

A series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, M_n = 1000), isophrone diisocyanate (IPDI), and 2,2′-dimethylol propionic acid (DMPA), followed by ionizing PU prepolymer with triethylamine (TEA). The second step involves PU chain-extended by water-soluble chitosan of low molecular weight (M_n = 5000) by self-emulsion polymerization method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infrared spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

膦化合物对加氢催化剂的影响

丁辛醇装置丁醛加氢催化剂在装置扩能投产以后热点上移 (失活 )的速率较快 ,针对催化剂老化的原因进行分析、判断 ,找出原因 ,采用相应的解决措施 ,可延长催化剂使用寿命 ,增加装置效益     

奇异值分解压制随机噪声的方法及应用

针对随机噪声压制问题，通过对多项式确定的同相轴形状重新选取数据矩阵，再对新选取的数据矩阵进行SVD滤波，从而压制随机噪声。通过对矩阵奇异值分解的研究，揭示了奇异值分解的原理和SVD滤波原理，将一个多道地震记录看作一个图，它可分解为由一系列正交的子图，通过对子图适当选择并结合其它手段，从而达到提高信噪比的目的，为奇异值分解在地球物理中的进一步应用提供了理论依据。实际数据应用表明，该方法去噪手段灵活、保真性好、分辨率高，对一些突然的脉冲干扰、侧反射、以及其他的反向干扰有明显效果。     

一个基于J2EE Web应用的框架设计与实现

J2EE(Java 2平台企业版)是当前建立和开发各种Web应用的主流平台,MVC(模型-视图-控制)体系结构是当今设计交互式应用的事实标准.文中结合MVC在J2EE Web中的应用,通过电子政务系统开发实践,提出了一个具体的实现方案,描述了应用系统设计,给出了表示层、控制层、代理层、业务逻辑层、数据访问层和数据存储层等层次的明确划分,阐述了各层的功能作用以及层与层之间的关系,并针对具体业务给出了实现的部分具体内容,为在J2EE环境下开发结构良好、易于维护、易于扩展的Web应用提供了可行方案.     

Preparation and Characterization of Carboxymethyl Chitosan and β-Cyclodextrin Microspheres by Spray Drying

Three kinds of carboxymethyl chitosan/β-cyclodextrin microspheres loaded with theophylline were prepared by spray drying intended for pulmonary delivery. Mucociliotoxicity, permeation rate, and drug release characteristics of the product were investigated. The microspheres obtained by spray drying were found to be spherical with smooth or wrinkled surfaces. The mean particle size was between 3.39 and 6.06 µm. The microspheres demonstrated high product yield (43.7-50.2%), high drug loading (13.7-38.1%), and high encapsulation efficiency (86.9-92.8%). FT-IR indicated that there were interactions of theophylline with carboxymethyl chitosan matrix. Further studies on mucociliotoxicity and permeation confirmed that microspheres had better adaptability and high permeation rate. In vitro drug release from the microspheres was not related to the drug/polymer ratios.     

基于LabWindows/CVI的多线程测控软件设计技术

多线程技术是W in32操作系统的一项重要软件技术。CVI 6.0及其以后版本提供了线程池和异步定时器两种多线程运行机制,为测控软件的设计开发带来了一次技术飞跃。文中结合测控软件设计实例,详细介绍了在CVI平台下多线程编程技术的应用方法。     

数字电视显示图像的同心度、重显率和过扫描

讨论了数字电视显示图像的同心度、重显率和过扫描，描述了它们的测量方法，重点分析了它们之间的内在联系，以及用它们来衡量显示图像质量的优缺点。实测表明，正确调整和测定这些指标，对保证数字电视图像主观效果具有重要作用。     

Synthesis of large building blocks for dendritic polyethers

Summary Building blocks containing multi-aryl ethers linkage in larger size for rapid building larger dendrimers were prepared with 3,5-di(4-hydroxyphenoxy)benzyl alcohol (1) as branch monomer and 1,3,5-tri(4-hydroxyphenoxy)benzene (2) as core molecule. Two generation of dendritic polyethers (12 and 15) were obtained by Fréchet convergent approach with 3,5-diphenoxybenzyl bromide (3) as starting molecule. They were characterized firstly by ¹H-NMR, ¹³C-NMR, and MS.     

碲镉汞外延晶膜的不稳定性

利用变温和变磁场霍尔测试对在空气室温环境长期存放的碲镉汞液相处延晶膜作了定期的检测，结果表明，晶膜的电学性质随时间有明显的改变，本文采用非均匀晶膜的层状模型对晶膜的不稳定性作了详细的分析。