高熔体强度聚丙烯制备技术的研究进展

综述了国内外高熔体强度聚丙烯(HMSPP)的制备技术,如共混法,后改性法(射线辐照法、过氧化物处理法、反应挤出法),催化聚合法,交联法的研究进展。介绍了HMSPP的大分子结构特点及其性能特征,分析了这些方法的特点及工业生产的适用性,对HMSPP的应用领域进行分析,并提出HMSPP制备技术的展望。催化聚合法是未来HMSPP乃至整个聚丙烯(PP)工业发展的方向,通过催化剂的改进和聚合工艺的优化实现高性能PP制备,是PP企业获得长久竞争力的根本。

Telomerase Activity in Human Renal Cell Carcinoma with Reference to Clinicopathologic Features

Objective: To study the telomerase activity in human renal cell carcinoma and to evaluate the correlation with the clinicobiologic features of the neogrowth.Methods: The telomerase activity was studied by means of a modified telomeric repeat amplification protocol (TRAP) in 32 renal cell carcinoma tissues, 32 normal renal tissues and 32 paracancer tissues and its correlation with the clinicopathologic features of the tumor was evaluated.Results: Telomerase activity was strongly positive in 17, positive in 12 and negative in 3 cases of renal cell carcinoma tissues, the total positive rate being 91%. Telomerase activity was weakly positive (6%) in only 2 out of 32 samples of normal renal cortex tissues and positive in 6 paracancer tissues (19%), the difference was conspicuous (P<0.01).Conclusion: The positive rate of telomerase activity was significantly higher in renal cell carcinoma tissues and might serve as a prognostic marker for estimating the biologic characteristics of renal cell carcinoma.

ZIF-8-DMTD@ALG气凝胶制备及对Pb(Ⅱ)、Cd(Ⅱ)吸附性能研究

文章利用合成后改性法将2,5-二巯基-1,3,4-噻二唑(DMTD)引入沸石咪唑酯骨架材料(ZIF-8),通过共混法将其与海藻酸钠(ALG)复合成功制备出ZIF-8-DMTD@ALG气凝胶。ZIF-8-DMTD@ALG气凝胶解决了粉末状吸附剂易团聚和难以回收的问题,DMTD的引入为ZIF-8-DMTD@ALG气凝胶带来丰富的官能团,从而提高其吸附性能。静态批量吸附实验表明:ZIF-8-DMTD@ALG气凝胶对Pb(Ⅱ)和Cd(Ⅱ)的吸附均遵循准二级动力学模型和Langmuir吸附等温模型;Langmuir模型拟合出的ZIF-8-DMTD@ALG对Pb(Ⅱ)和Cd(Ⅱ)的最大吸附容量分别达到352.101、170.592 mg/g。离子强度实验和循环吸附实验表明ZIF-8-DMTD@ALG气凝胶具有良好的耐盐性能和再生能力。表征技术和批量吸附实验结果揭示了ZIF-8-DMTD@ALG气凝胶主要通过络合作用吸附Pb(Ⅱ)和Cd(Ⅱ),少量的离子交换和静电作用也对吸附做出了贡献。该研究结果表明ZIF-8-DMTD@ALG气凝胶具有制备简单、回收容易和吸附能力强等优点,在实际污水处理领域有良好的应用前景。