过硼酸钠对于有机物的氧化作用的研究 II: 氧化偶氮硝基苯类的合成

作者曾报道过硼酸钠在醋酸溶液中可使芳氨基氧化成硝基;McKillop等曾报道将过硼酸钠用于官能团的氧化;Huestis曾报道在冰醋酸溶液中用过硼酸钠将芳胺氧化成偶氮苯。这些都表明过硼酸钠是一种优良的氧化剂,反应条件温和、选择性强、氧化剂本身。价廉且其还原后所生成的硼酸钠易于处理和排放。因此,值得深入研究其应用范围。我们在此则报道一组以过硼酸钠为氧化剂,使芳胺氧化成氧化偶氮苯的条件。最近我们发现,在乙醇-磷酸体系中,过硼酸钠能顺     

A High-Order Finite Difference Scheme for 3D Unsteady Convection Diffusion Reaction Equations北大核心CSCD

针对三维非稳态对流扩散反应方程,构造了一种高精度紧致有限差分格式,对空间的离散采用四阶紧致差分方法,对时间的离散采用Taylor级数展开和余项修正技术,所提格式在时间上的精度为二阶、在空间上的精度为四阶。利用Fourier稳定性分析法证明了该格式是无条件稳定的。最后给出数值算例验证了理论结果。     

Micro raman spectroscopy on a single carbon fibre under stress

An example is given for the application of Raman spectroscopy in material characterization. Raman spectra of carbonaceous materials obtained with the microscope attachment have been used to study orientation of graphite planes in a single carbon fibre under stress with a lateral resolution of 1 m.Dedicated to Professor Dr. H. Kriegsmann on the occasion of his 70th birthday     

A new inorganic-organic polymer for the passivation of thin film capacitors

Inorganic-organic polymers with barrier properties against water vapor, excellent electrical data (3, 2, R _D>10¹⁶ cm, E _D up to 400 V/µm) and good adhesion to various substrate materials have been developed. Tailored modifications of these materials provide an excellent protective coating for thin film capacitors. Several mm thick, expensive, encapsulations could be replaced by thin coatings (up to 10 µm). The polymer coating allows the use of thin film chip capacitors in surface-mount technology. As a measure for the efficiency of the coating, the capacitance decrease under controlled humidity has been used. The influence of the material composition, the type of catalyst during sol-gel processing and the curing conditions have been studied. Adhesion and water vapor permeation properties of the polymers and rheological properties of the coating solutions have been investigated. A protective coating is developed, which increases the withstandness of capacitors against humid conditions (90°C, 100% rel. humidity) by a factor of about 30 (compared to uncoated capacitors) and shows no crack formation during thermal cycling.