电感耦合等离子体原子发射光谱(ICP-AES)法测定四种奶片中的钙和镁

采用HNO3-HClO4混酸体系溶解奶片,电感耦合等离子体原子发射光谱法测定试样中的钙和镁含量,结果表明非糖果型奶片中钙和镁的含量较高。通过加标回收实验,钙和镁的加标回收率为96.7%～101%,相对标准偏差均小于3%,方法准确、快捷,为研究奶片在儿童成长发育中的作用提供了相关的依据。     

氯化银比浊法测定镍钴锰三元素氢氧化物中氯离子

建立了氯化银比浊法测定镍钴锰三元素氢氧化物中氯离子含量的测定方法。选择了合适的测定波长,并对硝酸用量、沉淀剂用量、稳定时间对测定结果的影响进行了试验,确定了较优的分析条件。样品加标回收率在95%~103.3%,氯离子浓度在0~4μg/mL与浊度值有良好线性关系。方法为控制镍钴锰三元素氢氧化物中氯离子提供了检测依据。     

铜卟啉-L-半胱氨酸自组装复合膜修饰电极的制备及电化学性能研究

利用电化学扫描法在L 半胱氨酸(Cys)自组装单分子膜修饰金电极表面现场制备了金属卟啉复合膜,对其进行SEM和ATR FTIR表征。修饰电极的支持电解质以及pH值对膜的稳定性和灵敏度有很大影响。铜卟啉 L Cys膜对H2O2具有良好的电催化还原特性,催化电流与H2O2浓度在1 0×10 6到3 0×10 5mol·L 1范围内线性关系,相关系数0 9995,检测限达1 0×10 7mol·L 1。     

钒离子掺杂对TiO2光催化剂薄膜催化活性的影响

采用溶胶凝胶工艺在普通玻璃表面制备了钒离子非均匀掺杂的TiO2薄膜,运用XRD研究了其光催化复合薄膜的表面特征.以光催化降解甲基橙溶液为模型反应,表征薄膜的光催化活性,结果表明,将钒离子富集在TiO2薄膜内部时,最佳掺杂浓度为1.0%(V/Ti原子百分比),最佳降解表观速率常数为7.44×10-3min-1,约是纯TiO2的2.3倍,有效地提高了TiO2半导体的光催化效率.通过XPS与电化学方法进行分析,说明将钒离子富集在TiO2薄膜内部十分有利于电子-空穴的分离,增强了光生电子与空穴的分离效率.     

Matrices for mono-material composites (MMC). The case of poly(ethylene terephthalate)

The use of the same thermoplastic polymer for both the matrix and the filler in the preparation of composites is very attractive, because such composites are in principle fully recyclable. Recently it has been reported the preparation of a mono-material composite (MMC) made of polypropylene to be used in automobile parts. In this work we report on the preparation and characterization of matrices for quasi MMC made of poly(ethylene terephthalate) (PET). Particularly we found PET copolymers containing isophthalate (IPA) units adequate to be used as matrix.     

薄板弯曲问题的复合傅里叶级数方法

解析方法与数值方法有效融合是提高计算效能的重要途径．提出薄板弯曲问题的复合傅里叶级数方法．它以解析方法为融合基体,数值方法为融合增强相,是一种新的融合模式．在这种新的融合模式中,傅里叶级数解析解作为变形场的连续表现形式,摆脱了载荷形式和边界条件的强烈依赖性,表现出良好的收敛性态．     

Study on resistance coefficient in compound channels

This paper presents a further study of the Manning and Darcy-Weisbach resistance coefficients, as they play a significant role in assessing the cross-sectional mean velocity, conveyance capacity and determining the lateral distribution of depth mean velocity and local boundary shear stress in compound channels. The relationships between the local, zonal and overall resistance coefficients, and a wide range of geometries and different roughness between the main channel and the flood plain are established by analyzing a vast amount of experimental data from a British Science and Engineering Research Council Flood Channel Facility (SERC-FCF). And the experimental results also show that the overall Darcy-Weisbach resistance coefficient for a compound channel is the function of Reynolds number, but the function relationship is different from that for a single channel. By comparing and analyzing the conventional methods with the experimental data to predict composite roughness in compound channels, it is found that these methods are not suitable for compound channels. Moreover, the reason why the conventional methods can not assess correctly the conveyance capacity of compound channels is also analyzed in this paper.The project supported by the National Natural Science Foundation of China (50279024), the National Key Basic Research and Development Program of China (973 Program) (2003CB415202) and the Specialized Research Fund for the Doctoral Program of Higher Education (20030610039)The English text was polished by Ron Marshall     

电感耦合等离子体质谱法(ICP-MS)测定镍钴锰三元氢氧化物中铅

研究了用电感耦合等离子体质谱法（ICP-MS）测定镍钴锰三元素氢氧化物中铅含量的测定方法。选择了仪器的最佳测量条件、元素测定的质量数,进行了基体元素的干扰等实验。方法测定结果准确、可靠,测定下限小于0.00005%,样品加标回收率在99.2%~101.0%。方法的建立为控制镍钴锰三元素氢氧化物中铅提供了检测依据。     

Mechanical properties of oriented low‐density polyethylene with an oriented lamellar‐stack morphology

A quantitative study was undertaken of the anisotropy of low‐strain mechanical behavior for specially oriented polyethylene with controlled crystalline and lamellar orientation. The samples were prepared by the die drawing of injection‐molded rods of polyethylene and annealing. This produced a parallel lamellar structure for which a simple, three‐dimensional composite laminate model could be used to calculate the expected anisotropy. Experimental data, including X‐ray strain measurements of the lateral crystalline elastic constants, showed good quantitative agreement with the model prediction. The X‐ray strain measurements confirmed that the amorphous regions exert large constraints on the crystalline phase in the lateral directions, where an order of magnitude difference was found between the measured apparent lateral crystalline compliances in the lamellar‐stack sample and the expected values for a perfect crystal. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 755–764, 2000     

Novel molecularly hybridized polyethylene/silica composite materials: Polymerization of ethylene with supported titanocenes by mesoporous silicates

A novel molecularly hybridized polyethylene/silica composite thin film was obtained by the gas‐phase polymerization of ethylene with a titanocene‐mounted mesoporous silica layer on a mica plate with mesoscopic pores arranged on the film surface. However, the use of titanocene‐mounted hexagonal domains of mesoporous silica on a glass plate for the gas‐phase polymerization of ethylene resulted in the formation of an islanded polyethylene/silica hybridized material. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4821–4825, 2000