HPLC-an Effective Method of DNA Fragment Determination

The role played by DNA in molecular biology is clearly recognized to be vital to life on this planet. 8-oxo-7,8-dihydro-2deoxyguanosine(=8-OHdG), is probably the most important product of "oxidative stress” in DNA. Its concentration in DNA is, in fact. a quantitative analysis of the degree of DNA damage that an organism has undergone. Due to the importance of 8-OHdG of nucleic acidg in mutagenesis, carcinogenesis and aging, numerous chemical and biological investigations have been made on this subject in the past time. Kuchino and co-workers have found that 8-OHdG residue in DNA is misreading during the process of DNA replication. Recently, some reports have been presented on high 8-OHdG levels in patients suffering from various diseases such as chronic hepatitis, Fanconi s anemia, diabetes mellitus and Helicobacter pylori infections. As a result, 8-OHdG is a useful marker for the study of DNA damage arising from reactive oxygen species and is of great significance for cancer research. The 8-OHdG levels in DNA can help understand the mechanism of carcinogens and lead to more effective treatments for many different types of cancer. For these reasons, an analysis of 8-OHdG with quickness, low cost and high accuracy is required.     

不同端基联苯型聚醚醚酮(PEDEK)齐聚物的合成

采取亲核取代反应合成了含有羟端基和不含羟端基的两种线性联苯型聚醚醚酮(PEDEK)齐聚物,并采用MS,¹HNMR,ICP,IR,DSC和WAXD等方法对齐聚物进行表征.研究发现,含羟端基的齐聚物因分子间存在氢键,其X射线衍射峰峰位和峰形与聚合物十分相似,而不含羟端基齐聚物的X射线衍射峰与聚合物相差较大.     

接枝共聚法制备聚乙二醇(PEG)/聚乙烯醇(PVA)高分子固-固相变材料性能研究

用接枝共聚法将具有相变特征的聚乙二醇(PEG)接枝到具有较高熔点的聚乙烯醇(PVA)主链上,得到了系列性能稳定的PEG/PVA高分子固-固相转变材料,用DSC,WAXD和POM对其相变行为及形态结构进行了研究.结果表明,该材料呈现出可逆的固-固相转变特性;其结晶峰值温度和相变焓比纯PEG低,接枝率对相变温度和归一化相变焓影响不大;接枝率只影响结晶与熔融行为,不影响结晶结构.     

红外窗口和整流罩材料研究现状与发展趋势

介绍红外窗口的三个综合性能评价因子:热破裂品质因子、光畸变品质因子、抗热冲击品质因子;并用它们评价了氟化镁、尖晶石、氮氧化铝、蓝宝石、硫化锌和硒化锌、金刚石等主要的红外窗口和整流罩材料;综述其国内外的研究现状,并对其未来的发展趋势发表了自己的观点.     

傅里叶变换红外光谱和近红外傅里叶变换拉曼光谱法无损鉴定中国字画

利用傅里叶变换红外(FTIR)和近红外傅里叶变换拉曼(NIR FT-Raman)光谱法鉴定了中国字画,结果表明：与荧光光谱法相比,根据谱峰的强度和位置可更容易地将真伪字画区别开来。拉曼光谱和红外光谱相互印证,互相补充,在鉴定中具有快速、准确、操作简单、重复性好、不需对样品进行预处理的优点,适于珍贵字画的无损鉴定。     

Electrospinning of ultra-thin polymer fibers

The electrospinning technique was used to spin ultra-thin fibers from several polymer/solvent systems. The diameter of the electrospun fibers ranged from 16 nm to 2 μm. The morphology of these fibers was investigated with an atomic force microscope (AFM) and an optical microscope. Polyethylene oxide) (PEO) dissolved in water or chloroform was studied in greater detail. PEO fibers spun from aqueous solution show a “beads on a string” morphology. An AFM study showed that the surface of these fibers is highly ordered. The “beads on a string” morphology can be avoided if PEO is spun from solution in chloroform; the resulting fibers show a lamellar morphology. Polyvinylalcohol (PVA) dissolved in water and cellulose acetate dissolved in acetone were additional polymer/solvent systems which were investigated. Furthermore, the electrospinning process was studied: different experimental lay-outs were tested, electrostatic fields were simulated, and voltage - current characteristics of the electrospinning process were recorded.     

Studies on Liquid Crystalline Bis[4-(p-phenoxy)-phenylbenzoate]-Alkyldicarboxylate

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Temperature Oscillations Characterized by An Overall Activation Energy

Temperature oscillations obtained during the heterogeneous catalytic oxidation of ethanol on Pd-Al₂ O₃ in a dynamic calorimeter were characterized by an overall activation energy. This parameter was determined by a non-isothermal kinetic method using the minimum and maximum values of the oscillations temperature. Using the bifurcation diagram with the oxygen as a bifurcation parameter an E value between 27.6 and 28.2 kJ mol^-1 was obtained. With ethanol as bifurcation parameter the E values lies between 28.1 and 31.1 kJ mol^-1 for 3.5 to 4.0 vol% ethanol and between 25.8 and 27.6 kJ mol^-1 for 4.0 to 4.7 vol% ethanol. These results have been discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定含硅镁合金中营养元素锶和钙

采用氢氟酸溶解硅,高氯酸冒烟除氢氟酸处理,利用电感耦合等离子体原子发射光谱(ICPAES)法测定生物医用可吸收含硅镁合金中营养元素锶和钙。对仪器参数以及被测元素的谱线选择进行了讨论。在选定最佳条件下,探讨了检测方法中检出限、精密度及加标回收率等指标,方法相对标准偏差小于1%(n=5),加标回收率为100.6%~117.2%。方法实用性强,已成功应用于含硅镁合金中锶和钙的测定。