Radioaktive Indikatormethode in der chemischen Verfahrenstechnik

The radioactive tracer method in the chemical industry. In the chemical industry the radioactive tracer method has become a method of analysis with a variety of applications, which range from determining traces of biologically active substances to process analysis in production plants. Process analysis, for instance the determination of residence-time distributions or of intermingling of streams of different substances, can be carried out under widely varying operating conditions. If the streams of material are labelled with gamma-ray emitters the distribution of the tracers can be determined by means of detectors outside the plant. To demonstrate the possible applications of the method to process analysis, measurements in three different plants are described. Exhaust gases were labelled with Ar-41 to determine the residence-time distribution in plant for the combustion of waste residues consisting of a rotary tube furnace, an afterburn chamber, and a waste-heat boiler. The waste water entering the activation tank of sewage-treatment plant was labelled with Na-24 to determine its residence-time distribution. Individual particles labelled with Mn-56 were used to investigate mixing of the powder in the stirred-bed reactor of a polypropylene plant. The knowledge gained from these measurements has contributed to optimization of existing and planned plant.     

An Ontological Approach to Evaluating Standards in E-Commerce Platforms

This paper identifies and defines standards required for successful e-commerce (EC) platforms. It presents an ontology of standards and applications that can be used to evaluate any EC platform. Current platforms are limited in usefulness and development economy by lack of standards. We describe how the development and use of such standards could help improve EC platforms. We examine the current and emerging platforms and technologies in relation to the proposed ontology including electronic data interchange, e-procurement systems, business-to-business hubs, company WeWeb b sites, electronic business eXtensible markup language, Web services, the semantic Web, and universal business language. We conclude that no individual platform or technology provides complete support for every level of the ontology, and we suggest that combinations of features from various platforms and technologies may be of most value. We conclude that research is needed in three areas: the discovery phase of EC, participant incentives for standardization, and methods of combining useful aspects from different standards bodies.     

Comparative analysis of promoter regions containing binding sites of the heterodimeric transcription factor Ino2/Ino4 involved in yeast phospholipid biosynthesis

The inositol/choline responsive element (ICRE) functions as a UAS element mediating coordinate expression of structural genes required for yeast phospholipid biosynthesis. However, ICRE motifs could be detected upstream of various genes apparently not involved in lipid metabolism. In this work we investigated the expression pattern of selected genes containing ICRE promoter motifs, as identified by in silico analysis (ARG4, ERG20, FAR8, GPD2, RSF1, URA8, VHT1 and YEL073C). It turned out that the presence of an ICRE upstream of a gene of unknown function indeed allows to conclude for regulation by phospholipid precursors, which is mediated by activators Ino2/Ino4 and the repressor Opi1. We also demonstrated in vitro binding of Ino2/Ino4 heterodimers to promoter regions. Thus, our analysis supports the view that identification of regulatory elements by a database search provides evidence for a specific pattern of gene expression. Activation by pathway-specific regulators may suggest a physiological function for as yet uncharacterized genes.     

Flutter and Buffeting Analysis.?I: Finite-Element and RPE Solution

A finite-element formulation is developed for analyzing flutter instability and buffeting response of long-span bridges and their interaction. The flutter derivatives, instead of the indicial functions used by previous researchers, are applied in the random parametric excitation (RPE) analysis. This application makes finite-element formulation possible and results in much less computational effort in RPE analysis than those of previous analyses. With the finite-element program developed in the present study, as many modes as desired can be easily included in the flutter and buffeting analyses. Users have the choice of RPE or eigenvalue method for flutter analysis and RPE or spectral method for buffeting analysis.     

Advances in Tangible Interaction and Ubiquitous Virtual Reality

The first article reports on context-sensitive augmented-reality research presented at the 2007 International Symposium on Ubiquitous Virtual Reality. This student-organized event explored the use of contextual information, design principles, and effective user evaluation for developing AR applications for ubiquitous computing environments. The second article reports on The International Conference on Tangible and Embedded Interaction, the first conference series worldwide to focus on tangible and embedded interaction. The conference is interdisciplinary, covering the arts, hardware design, software toolkits for prototyping, and user studies and theory development.     

Interface Molecular Engineering for Laminated Monolithic Perovskite/Silicon Tandem Solar Cells with 80.4% Fill Factor

A multipurpose interconnection layer based on poly(3,4‐ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), and d ‐sorbitol for monolithic perovskite/silicon tandem solar cells is introduced. The interconnection of independently processed silicon and perovskite subcells is a simple add‐on lamination step, alleviating common fabrication complexities of tandem devices. It is demonstrated experimentally and theoretically that PEDOT:PSS is an ideal building block for manipulating the mechanical and electrical functionality of the charge recombination layer by controlling the microstructure on the nano‐ and mesoscale. It is elucidated that the optimal functionality of the recombination layer relies on a gradient in the d ‐sorbitol dopant distribution that modulates the orientation of PEDOT across the PEDOT:PSS film. Using this modified PEDOT:PSS composite, a monolithic two‐terminal perovskite/silicon tandem solar cell with a steady‐state efficiency of 21.0%, a fill factor of 80.4%, and negligible open circuit voltage losses compared to single‐junction devices is shown. The versatility of this approach is further validated by presenting a laminated two‐terminal monolithic perovskite/organic tandem solar cell with 11.7% power conversion efficiency. It is envisioned that this lamination concept can be applied for the pairing of multiple photovoltaic and other thin film technologies, creating a universal platform that facilitates mass production of tandem devices with high efficiency.     

Properties of niobium-based Josephson tunneling elements in junction microstructures

We describe the fabrication and electrical characteristics of niobium oxide-barrier tunnel junctions with counterelectrodes of lead/lead alloy. Primary attention is directed to the experimental conditions necessary to obtain high-quality tunnel barriers as well as studies on characterizing the atomic structure of the barrier region. In order to study the tunnel barrier homogeneity in the tunneling region the magnetic field dependence of the critical Josephson current is investigated. TheI–V characteristics and dependence of the critical Josephson current on temperature are analyzed quantitatively by using a proximity effect model. Finally, we discuss experimental results on the improvement of junction quality by including traces of carbon in the rf argon plasma during the sputter cleaning of niobium base electrodes.