SONIC-新一代快恢复二极管

在这篇文章中,介绍了平面型SONIC软恢复二极管的新系列,电压范围从600V到1800V,并有不同的额定电流。采用从硅片背面进行深的磷扩散和控制轴向寿命抑制剂的办法开发出了带有拖尾电流的快恢复及软恢复二极管。被提及的二极管在整个工作温度范围内性能稳定,并且对于温度的变化正向电压降的变化可以忽略不计。SONIC二极管是为高频应用而设计的,在高频应用方面需要稳定的开关特性。文章还比较了SONIC二极管和用铂或金作为寿命抑制剂的标准快恢复外延二极管(FRED)在25℃到125℃下的开关损耗。     

Schwermetall- und chloridhaltige Filterstäube. I. Phasenanalysen und Modellversuche zum Recycling

Flue Dusts Containing Heavy Metal Ions and Chloride.I. Phase Analysis, Model Experiments for Recycling Four flue dusts from a cement factory, an electric-furnace steelmaking plant and a municipal waste plant were analyzed by powder diffraction methods. Chloride combines above all with alkali ions or heavy metal ions, especially yielding PbCl₂ and KPb₂Cl₅. The controlled sublimation of these chloride compounds in open crucibles was developed and optimized in our laboratory. Between 850°C and 1150°C and at reaction times from 30 min up to 12 h, the chloride content decreases to below 0.1 wt-%. The sublimed phase mainly consists of alkali and lead chloride. Zinc is found in the flue dust as oxide and is enriched during this process. Recent investigations with a small waelz kiln give analogous results. With our procedure, the manufacturer by himself is able to exploit flue dusts containing a large amount of heavy metal elements and chloride which cannot be deposited. The remaining product contains mainly zinc oxide which can be recycled in the zinc industry or returned to the production process. The sublimed chloride compounds may be recycled in the potash industry.     

Molecular basis of lipase stereoselectivity

Lipases exhibit specific catalytic properties that make them attractive to biotechnological applications. Most important are the broad substrate specificity and the regio‐ and stereoselectivity of lipases. Despite mechanistic and structural similarities lipases differ significantly with respect to stereoselectivity toward natural and synthetic substrates. Models developed to describe and predict stereoselectivity toward certain types of synthetic substrates, e. g., secondary alcohols cannot be applied to natural acylglycerols, that are hydrolyzed by several animal and microbial lipases in a regioselective or stereoselective manner. Therefore, computer‐aided molecular modeling studies were used in order to predict the stereopreference of lipases toward triradylglycerols. Lipase variants with modified stereoselectivity properties toward triacylglycerols were engineered by re‐designing the recombinant enzyme. To understand the interactions governing lipase stereoselectivity towards natural substrates, knowledge of the structure of enzyme‐substrate complexes at the atomic level is essential. Such information can be obtained by X‐ray or NMR analysis of covalent enzyme‐inhibitor complexes. The crystal structures of enzymes complexed with triacylglycerol analog inhibitors allowed the identification of distinct binding sites for the three hydrophobic chains of the inhibitor.     

Enhancing DPCD in Liquid Products by Mechanical Inactivation Effects: Assessment of Feasibility

The enhancement of standard dense phase carbon dioxide (DPCD) pasteurization by additional mechanical effects was assessed in this work. These effects were induced during pasteurization by the sudden depressurization in a narrow minitube. The high flow velocities, moderate pressures (40–80 bar) and low temperatures (25–45 °C) lead to intense degasification and shear stress. The inactivation of the test microorganism Escherichia coli DH5α (E. coli DH5α) was determined before and after depressurization in the minitube, representing entirely chemical DPCD via dissolved CO₂ and total inactivation comprising the effects of dissolved CO₂ and mechanical effects, respectively. Compared to conventional DPCD pasteurization, which is mostly attributed to chemical effects, the additional mechanical effects increased the inactivation efficiency considerably.     

Kinetische Parameteridentifikation und Modelldiskriminierung am Beispiel der nassen Oxidation von Thiosulfat

Coke technology involves polluted wastewater, which must be treated efficiently in order not to pollute the environment and to comply with legal regulations. This requires a thorough understanding of the process. Due to the large number of possible modifications, sulfur compounds occupy a special position and, thus, knowledge of the reaction pathways and kinetics is essential for the design of apparatuses. By means of parameter estimation and model discrimination, kinetics are determined on the basis of experimental data and reaction schemes of the wet oxidation of thiosulfate are evaluated in order to describe the concentration course of all species with sufficient accuracy.