Interaction between poly（amidoamine） dendrimers and DNA studied by spectroscopic methods

The interaction between amino-terminated, and ethylenedtamine core poly（amtdoamine） （PAMAM） dendrimers and herring sperm DNA was investigated by various spectroscopic methods including UV spectroscopy, fluorescence spectroscopy, microscopic FTIR- and circular dichroism （CD-） spectroscopy. Ethidium bromide （EB） is used as a nucleic acid probe for this study. Experimental results show that PAMAM dendrimers can form stable complexes with DNA and the dendrimers bind to DNA sufficiently strong which cannot be displaced by EB, and we also found that the formation of the complexes can cause the conformation change of the DNA secondary structure. According to the Scatchard analysis, the association constant of PAMAM to DNA is calculated to be 2.53×10^4 mol/L^-1.     

pH-responsive poly（2-diethylaminoethyl methacrylate）-functionalized multiwalled carbon nanotubes

Poly（2-diethylaminoethyl methacrylate） （PDEAEMA）-coated multiwalled carbon nanotubes （MWNT-PDEAEMA） were successfully prepared by MWNT-surface initiated atom transfer radical polymerization （ATRP）. The obtained MWNT-PDEAEMA nanocylinders have a core of MWNT and a shell of PDEAEMA and this core-shell structure was confirmed by TEM observations. The UV-Vis and AFM measurements showed that the MWNT-PDEAEMA exhibited obvious pH sensitivity. The solubility of PDEAEMA-coated MWNT dramatically decreased when pH increased to ca. 7.0. Because of the giant molecular weight of the molecular hybrids and local high density of polymeric grafts linked onto MWNTs, the resulting MWNT-PDEAEMA nanocomposites are easier to aggregate, or more sensitive to pH, as compared with the neat PDEAEMA.     

Behavior of MC3T3-E1 Osteoblast Cultured on Chitosan Modified with Polyvinylpyrrolidone

The physical and chemical properties of four kinds of modified chitosan materials made by blending chitosan with polyvinylpyrrolidone （PVP） were investigated. All four of these modified chitosan materials were hydrophilic with water contact angles ranging from 59°to 69°. Fourier transform-infrared spectra of the modified materials showed a new band at 1288 cm^-1, implying formation of a surface physical interpenetrating network structure. Enzyme linked immunosorbent assay results indicated that much less fibronectin was adsorbed on the modified materials than on only chitosan. The viability of MC3T3-E1 osteoblasts cultured on the materials was assessed by 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl- 2H-tetrazolium bromide assay. The results show that adding PVP10000 into the chitosan promotes adhesion of MC3T3-E1 osteoblasts on the modified materials, but has no effect on cell growth and proliferation; while adding PVP40000 reduces cell adhesion, growth, and proliferation. The results suggest that the increased hydrophilicity of the material surface does not always improve its biocompatibility, which will influence the selection and design of biomaterials.     

层离高密度聚乙烯/层状双氢氧化物纳米复合材料的制备

采用熔融插层法制备了高密度聚乙烯（HDPE）／层状双氢氧化物（IDH）纳米复合材料．结构分析表明，当LDH含量低于5％时，LDH片层在纳米复合材料中是完全层离的．热性能分析表明，所得HDPE／LDH纳米复合材料比纯HDPE具有更高的热稳定性．以50％失重为比较点，当LDH含量为5％时，HDPE／LDH样品的降解温度比纯HDPE高出达40℃．     

柴油蜡晶分散剂的制备和降凝效果研究

以马来酸酐和呋喃为原料，经Diels-Alder反应、酯化／酰胺化后合成了柴油蜡晶分散剂3，6-氧桥-1，2，3，6-四氢苯-1，2-二甲酸高级酯／酰胺。酸值测定表明，该合成方法的产率超过90％。对大庆0^#柴油的冷滤点测试表明，该醋晶分散剂与低相对分子质量的乙烯-醋酸乙烯酯共聚物复配效果较差，而与改性的聚丙烯酸高级醇酯二元复配后，可以降低冷滤点7℃，表现出了良好的协同效应。     

转光剂的制备及在农膜中的应用

以稀土碳酸物、邻菲咯啉与噻吩甲酰三氟丙酮为原料合成了Ce0．5Sm0．5（TYA）3（Phen）H2O的配合物，该配合物能有效吸收270～380nm范围的紫外光，在约400nm处产生强的蓝色荧光；经差热热重测定（DTG），分析了配合物的热稳定性和热分解行为；与聚乙烯膜具有很好的结合力，且不影响薄膜的加工工艺，在薄膜加工中原有组分的光学性能保持不变。     

LDPE-g-MAH对LDPE/PA6共混物的增容作用

探讨了LDPE－g-MAH/PA6共混物的流变性能，并同LDPE／PA6共混物作了对比，研究结果表明：LDPE－g-MAH-PA6共混物熔体的流变行为符合假塑性流体的流动规律，其流变指数转小，熔体粘度比LDPE／PA6共混物高。     

聚乙烯包膜尿素的研制

对PE包膜尿素的制备工艺，淋溶速度及物理机械性能进行了探讨，表明该产品可有效控制氮的释放，达到减少尿素流失，提高利用率的目的。     

Θ条件下聚乙烯型链分子构象统计的Monto-Carlo研究

本文采用聚乙烯型链分子的实际键长与键角及由旋转异构态模型导出的条件概率进行构象统计的Monto-Carlo研究，并与Flory矩阵法、完全计算法进行比较，结果表明我们提出的计算方法快速且精度极高。此外也对聚乙烯链的三态和五态模型的计算进行了比较。     

防蜡降粘剂RTPP的应用研究

本文介绍了新型防蜡降粘剂RTPP，现场应用结果表明，该产品在原油集输过程中起到良好的减阻、降粘作用，改善了原油的流动性能，达到了节能降耗的效果。