Dynamic mechanical,rheological, and morphological studies of polyacrylate-graft-poly (vinyl chloride) suspension resin

A series of polyacrylate-graft-poly (vinyl chloride) (ACR-g-PVC) resins were prepared through suspension graft copolymerization. Three kinds of polyacrylate latices were grafted by vinyl chloride using suspension polymerization method at 57 ± 0.1°C, respectively. The dynamic mechanical and rheological properties and the morphology of the resulting ACR-g-PVC resins were investigated. Poly (butyl acrylate)-graft-poly (vinyl chloride) (PBA-g-PVC) resin exhibited better toughness, and the optimized content of PBA in ACR-g-PVC resin was 6–8 wt%. The melt viscosity of ACR-g-PVC resin was much lower than that of pure PVC. The nature of the fracture surfaces of ACR-g-PVC material indicated that it has good toughness. The impact strength of the PBA-g-PVC material was greatly improved compared with that of pure PVC. The Young's modulus of the ACR-g-PVC material containing less than 15 wt% of PBA was comparable to that of pure PVC according to their dynamic mechanical analysis curves. For all of the ACR-g-PVC resins, there were two individual relaxations in the low-temperature range. One was β transition of PVC, and the other was α transition of ACR. The glass transition temperature of PVC in the ACR-g-PVC resin shifted to lower temperature when the content of the PBA was above 50 wt%. POLYM. ENG. SCI., 47:996–1003, 2007. © 2007 Society of Plastics Engineers     

具有完整TCP/IP协议支持的U-Boot

在保护装置中最为稳定的引导程序U-Boot中实现了对该通用调试软件的通信协议的支持。基于U-Boot提供的独立应用开发框架,将独立的具有完整TCP/IP协议支持的lwIP协议栈移植至U-Boot。基于该协议栈以及U-Boot的独立应用开发框架,实现了对通用调试软件的复杂通讯协议的完整支持。经过上述技术改进,极大地扩展了通用调试软件的适用范围,加快了变电站工程实施中遇到的各种装置类似问题的解决速度。     

有限元方法在玻璃成形工艺研究的应用

分析了玻璃在熔融状态下的力学性质、弹粘塑性和刚粘塑性本构方程以及玻璃成形的力学特性等,并结合玻璃成形的热力学公式,介绍了对玻璃成形的热力耦合分析的基本原理,还介绍了在玻璃成形过程中玻璃和模具之间的非线性接触、摩擦问题的求解,自动网格重划分技术.为了说明玻璃成形有限元分析的过程,最后介绍了利用三维大变形有限元方法来模拟电视显像管管屏的压制成形过程和饮料瓶吹制成形过程.     

论港口危险货物运输装卸作业安全问题

危险货物作业安全越来越受到人们的关注，从危险货物的分类谈起，分析了危险货物港口运输装卸作业中易引发事故的诸因素和安全作业中应特别注意的几个问题，强调从业单位、从业人员的资质、法律意识和业务素质，制定危险货物事故应急预案等。提出了加强港口危险货物安全管理的有关建议：开展危险源与事故隐患的多层次监控；推进港航危险货物企业建立安全质量标准化体系；创建“抓小放大”的安全管理机制。     

多孔催化剂效率因子的多组分扩散模型(Ⅴ) 表面中毒并伴有平衡死区圆柱状催化剂效率因子的有限元求解

针对表面中毒并伴有平衡死区二维圆柱状催化剂的反应-扩散偏微分方程组的特殊性,引入有限元方法求解该类问题,建立了求解步骤。实际计算所得效率因子与实验值对照表明,本法结果准确,过程简单,容易推广应用于各种相类似的体系。     

Intercorrelations among plasma high density lipoprotein,obesity and triglycerides in a normal population

The interrelationships among fatness measures, plasma triglycerides and high density lipoproteins (HDL) were examined in 131 normal adult subjects: 38 men aged 27–46, 40 men aged 47–66, 29 women aged 27–46 and 24 women aged 47–66. None of the women were taking estrogens or oral contraceptive medication. The HDL concentration was subdivided into HDL_2b, HDL_2a and HDL₃ by a computerized fitting of the total schlieren pattern to reference schlieren patterns. Anthropometric measures employed included skinfolds at 3 sites, 2 weight/height indices and 2 girth measurements. A high correlation was found among the various fatness measures. These measures were negatively correlated with total HDL, reflecting the negative correlation between fatness measures and HDL₂ (as the sum of HDL_2a and_2b). Fatness measures showed no relationship to HDL₃. There was also an inverse correlation between triglyceride concentration and HDL₂. No particular fatness measure was better than any other for demonstrating the inverse correlation with HDL but multiple correlations using all of the measures of obesity improved the correlations. Partial correlations controlling for fatness did not reduce any of the significant correlations between triglycerides and HDL₂ to insignificance. The weak correlation between fatness and triglycerides was reduced to insignificance when controlled for HDL₂. Presented (in part) at the Annual Meeting of the Oil Chemists' Society in St. Louis, MO, May 1978.     

Preparation and modification of macroporous epoxy‐triethylenetetramine resin for preconcentration and removal of Hg(II) in aqueous solution

A novel macroporous resin was prepared from epoxy resin and triethylenetetramine through a polymerization with phase separation. In this experiment, the polyethylene glycol (PEG‐1000) plays a very important part. It was used as solvent, as phase‐separation reagent in the preparation processes, and as the pore‐forming reagent through removing PEG‐1000 from polymer by water‐cleaning process after completing polymerization. The prepared resin was modified by carbon bisulfide and soaked in 1 mol L^?1 NaOH. Its structure was characterized by Fourier transform‐infrared spectra, scanning electron microscopy, and elemental analysis. The adsorption characteristic of the chelating resin was studied by series of experiments. The results show that the chelating resin possesses excellent adsorption characteristic toward trace Hg(II). The recovery can come to 100% when the concentration of Hg(II) is only 0.05 ppm, and the average maximum adsorption capacity of the chelating resin for Hg(II) is 122 mg g^?1. The precision (relative standard deviation) for six replicate adsorbent extraction of 0.01 μg mL^?1 Hg(II) was 1.1%. The accuracy of the proposed procedure was verified by analyzing a standard reference material. Moreover, the chelating resin was applied to two natural samples and also got satisfactory results. That is to say, the chelating resin modified by carbon bisulfide exhibits a high chelating ability toward Hg(II) and can be used as adsorbent for preconcentration and removal of trace Hg(II) in aqueous solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2372–2378, 2006     

英汉委婉语的相似性与差异性

英语和汉语中都有许多委婉表达的用语.从委婉表达的表现手法、委婉语词源、委婉表达的社会价值观和审美观原因等方面分析比较了英汉委婉语的相似性和差异性.     

最优培养基配比方案的数学建模与求解

通过对实验数据的分析,用拟合和逐步回归的方法建立了最优配比方案的数学模型并进行了求解,所得结果与实验数据基本吻合,具有合理性。