Experimental studies on the ring opening polymerization of p-dioxanone using an Al(OPr)3-monosaccharide initiator system

The ring opening polymerization (ROP) of p-dioxanone using a protected monosaccharide (1,2;3,4-di-O-isopropylidene-α-d-galactopyranose)/Al(OⁱPr)₃ initiator system to yield polydioxanone with a protected monosaccharide end-group is described. The products were synthesized at 60-100 °C and characterized by ¹H and ¹³C NMR, and MALDI-TOF mass spectrometry. Besides the desired polydioxanone functionalised with a monosaccharide end-group, also polydioxanone with an OⁱPr end-group was formed (20-30%). Systematic studies showed that the polymer yield is a function of the reaction temperature and the reaction time, with higher temperatures (100 °C) leading to lower yields. The average chain length of the polymers is between 7 and 58 repeating units and may be tuned by the monomer to monosaccharide ratio (at constant Al(OⁱPr)₃ intake). A statistical model has been developed that successfully describes the experimentally observed relation between the average chain length of the functionalized polymer and reaction parameters.     

构建可扩展的网络服务：理论和实践

随着计算机网络变得越来越复杂，在网络上部署大规模的服务也愈加困难。为此本书在介绍了可扩展的网络基础设施和在网络系统设计领域内的大量实验内容的前提下，提出了一个分层可扩展的服务模型，并且评价了在该结构模型下运行的各种服务的性能。除此之外，本书还囊括了一系列的理论结果，并且可以应用在真实的网络环境下，如构建全网范围内的测量、监测服务以及构建更好的p2p网络的策略。