Third International Congress for Stereology

This article gives a survey of the actual experience with the relatively new technique of photo-emission electron microscopy. After describing the principal technique and the features of a modern high resolution instrument, the questions of image generation, contrast formation and resolution are considered. In particular the influence of the depth of information on resolution for flat polished sections is studied and some comparisons with the scanning electron microscope (SEM) are made.* The different fields of application of the photo-EEM are shown by examples.     

Wasserstoff-Energiewirtschaft aus kritischer Sicht

A critical view of the hydrogen economy . The goal of the hydrogen economy is to replace electrical energy, petroleum products, and natural gas wherever feasible by hydrogen as secondary energy. Apart from the coal the only primary energy source which be available in the near future will be nuclear energy, preferentially for supplying process heat for coal gasification (high temperature reactor). There will hardly be a future for thermochemical cyclic processes for cleavage of water; development of electrolytic process utilizing electrical energy from nuclear reactors appears technically and economically more promising. Exploitation of solar energy for generation of hydrogen appears unlikely in this century. The original concept of the hydrogen economy was associated with the discovery of hydrides of intermetallic compounds which are suitable for reversible storage of hydrogen. During the ensuing 15 years since the pioneering studies on this topic extensive detailed knowledge has accrued about the thermodynamic behaviour of hydride storage systems, their lattice structure, and the uptake and release of hydrogen. In any case, the hydrogen economy will be expensive with regard to both development and the necessary investment in this application.     

Der Einfluß einer langzeitigen Glühung bei 500 bis 700 °C auf das Kriechverhalten des Stahles 13 CrMo 4 4 bei 550 °C

Aufnahme von Zeit-Dehnung-Kurven über 1000 h bei 550 °C an einem Stahl mit 0,12% C, 0,86% Cr und 0,46% Mo nach 30- bis 10000 stündigem Glühen bei 500 bis 700 °C. Untersuchung der durch die Glühebehandlungen verursachten Änderungen im Feinbau des Werkstoffes durch Messung der Änderungen des elektrischen Widerstandes und der Koerzitivfeldstärke, durch Ermittlung der Streckgrenze und der Zugfestigkeit, durch lichtoptische Gefügebetrachtungen sowie durch chemische und röntgenographische Untersuchungen von Isolierungsrückständen.     

Erfassung,Beschaffung und Montage von Rohrleitungsteilen

Assessment, acquisition, and assembly of pipe components . Pipe technology accounts for ca. 30 to 35% of the planning of chemical plant and refineries. The reason for this high proportion lies in the numerous possibilities of variation. Each part must be defined, assessed and executed. The programme system developed consists of an assembly of several individual programmes which utilize available data. The overall procedure, from specification to assembly, is performed or supported by this programme system. The “general text system” (ATS) stores all pipe texts and pipe classes in several languages. With the aid of the “Lurgi piping macro-system” (LUROMAK ) the piping components are processed on the basis of flow charts, assembly plans and isometric drawings. The materials determined are transformed into buying information by the “execution system” (DISPO ). Registration of material entering and leaving stores in the “assembly organization system” (MOS) permits work preparation for assembly on the basis of the resulting stocks. It is also possible to assess the progress of assembly and to prepare costing information. The continuous processing of piping is permitted by a systematic standardization and classification, accomplished in particular by uniform definition of piping components in the ATS programme system.     

利用加密FPGA保护系统设计维护知识产权

随着半导体集成密度的提高及单位逻辑门成本的直线下降,使用可编程逻辑器件的系统所面对潜在的克隆和反向工程问题,已经成为真正的威胁.因此,系统设计人员必须时刻考虑知道产权保护问题及所用器件的保密性.采用非挥性Flash或反熔丝为基础的FPGA,对系统成本的影响甚微,却可提供高度的设计保密性.     

Guidance for Exposure and Risk Evaluation for Bystanders and Residents exposed to Plant Protection Products during and after Application

Plant protection products are applied in agriculture and horticulture in areas that may be accessible to the public. This means that individuals might be exposed who are not actively involved in the application of these products. The individual may be temporarily located in the vicinity of the application (the so-called ‘bystander’) or working or living in the vicinity of the application (the so-called ‘resident’). In this guidance paper scenarios for the evaluation of exposure associated with plant protection product application for bystanders and for residents (including children) are described. Received: June 20, 2008; accepted: June 26, 2008     

Environmental influences on the partitioning and diffusion of hydrophobic organic contaminants in microbial biofilms

A biofilm reactor was used to investigate kinetic and thermodynamic aspects of the sorption of polycyclic aromatic hydrocarbons (PAH) as model compounds for hydrophobic organic contaminants (HOC) to intact microbial biofilms. Effective diffusion coefficients are in the range of 10(-10) cm2 x s(-1) resulting in equilibration times of more than 3 days for a biofilm of 100 microm thickness. Diffusion in the biofilm was strongly temperature-dependent and increased by a factor of 3 (phenanthrene) to 6 (fluoranthene, pyrene) between 5 and 35 degrees C. Drying and rewetting of the biofilm as well as the inclusion of Ca2+ ions and of humic acids all strengthened the biofilm rigidity and slowed down the diffusion of PAH. The later two factors also influenced the thermodynamics of the process as they supported the partitioning of PAH into the biofilm. Humic acid inclusion from solution into the biofilm illustrates that a microbial biofilm can act as a primer allowing for the buildup of a particulate organic phase from dissolved organic matter. PAH metabolites (3-hydroxy-phenanthrene and 1-hydroxy-2-naphthoic acid) showed lower partition coefficients as compared to their parent compounds and 3-hydroxy-phenanthrene also showed a higher diffusion constant, indicating that these transformation products would be easily released into the water phase upon formation during PAH biodegradation in a biofilm. These results allow the quantification of the influence of environmental conditions on a biofilm's function as a sink or as a diffusion barrier for PAH from aqueous solution, and they indicate the importance of kinetic aspects of this partitioning process.