High resolution imaging and elemental analysis of PAGE electrophoretograms by scanning proton microprobe

Metal content of metalloproteins can be detected and even quantified by the PIXE–PAGE method. In this technique the proteins are separated by thin layer electrophoresis (by polyacrylamide gel electrophoresis (PAGE) in most cases) and the properly dried gel sections are analyzed by PIXE using “band-shaped” proton milli-beam. This PIXE–PAGE method was adapted for our scanning proton microprobe. The microPIXE–PAGE version provides two-dimensional elemental mapping of the protein bands. In addition, the fast continuous scanning reduces the risk of the thermal deterioration of the sample and the X-ray contribution from dust-impurities can be filtered out in the data evaluation process.     

Etablierung eines Frühwarnsystems zur Erkennung lebensmittelbedingter Risiken in Bayern – risikoorientierte Lebensmittelüberwachung weiter gefasst

Recent and past food scandals highlight the urgent need for food safety authorities to anticipate future risks in order to enable improved and proactive response mechanisms. With this goal in mind, the Bavarian Health and Food Safety Authority (LGL) has established an early warning system aimed at early identification of potential health risks and fraudulent practices in the food sector. The early warning approach allows intervention at different stages of risk development. On the one hand, the scanning of a broad area of the food production chain (horizon scanning) may enable prospective risk identification. To this end, relevant factors of influence (drivers) need to be identified, observed and analyzed. On the other hand, the retrospective analysis of case studies may unravel novel cause-effect associations that could be transferred to other products and production technologies, possibly leading to the identification of new drivers (root cause analysis). Additionally, various datasets emanating from food safety authorities, for example data from the European Rapid Alert System for Food and Feed (RASFF) and from Bavarian-wide laboratory analyses and food business inspections, will be closely observed and analyzed. The multidisciplinary character of the LGL has proven to be essential for the realization of the early warning approach, the analysis of inflowing data and implementation of consequences such as food business inspections and sampling for analysis. This article details the objectives and methodical approaches of the project. The acquisition of systematically compiled information as well as its analysis and assessment are comprehensively described. The early warning system presented here has already contributed significantly to the risk-oriented food inspection practiced to date, by integrating novel risk-relevant aspects.     

The influence of a corrosive wood-cutting environment on the mechanical properties of hardmetal tools

The influence of a corrosive wood-cutting environment on the strength of hardmetals and on their behaviour under static loading conditions has been investigated. Two commercial hardmetals were tested, which differed in hard phase composition. The results show exposure to this environment to have a highly detrimental influence on the strength of both hardmetals investigated, due to localised corrosive attack which results in the formation of stress raisers. The relative loss in strength as a function of corrosion time is the same for both hardmetals. However, the performance of the two grades differ significantly when a static load is applied in this corrosive environment: the strength of the WC-Co grade remains unaffected by the applied load, while the grade containing a mixed carbide phase exhibits stress corrosion cracking which results in a further reduction in strength.     

Conversion of carbon into CF4 for SI-traceable measurements of absolute carbon isotope amount ratios: a feasibility study

The feasibility of performing SI-traceable carbon isotope amount ratio measurements following conversion of carbon into CF4 was studied. A procedure for the direct fluorination of carbon with elemental fluorine was developed, and the conversion step was checked for losses, blank contributions, and the absence of systematic isotope effects. Gas chromatography was used to identify and quantify the gaseous fluorination products and to isolate CF4 from byproducts. After fluorination of graphite carbon, CF4 and perfluoroalkanes with up to six carbon atoms were observed as reaction products. Within an uncertainty of 10%, the graphite carbon was fully recovered in the gaseous carbon fluorides, with the main product being CF4 (80-90%) and C2F6 as the major byproduct. The fluorination and GC procedures were found to introduce an alteration not bigger than 0.03 +/- 0.04/1000 on the isotopic composition of CF4. Carbon blank contributions introduced during the fluorination procedure were below 0.5% relative to a typical sample of 4 mg of carbon. For two of the materials investigated, the carbon isotope ratios measured on a differential mass spectrometer were reproducible within a standard deviation of approximately 0.1/1000 for several individual fluorinations. For these materials, the developed fluorination procedure is a straightforward process, which can be used as a foundation to establish SI-traceable measurements of carbon isotope amount ratios. However, for the third graphite material the formation of byproducts (C2F6-C6F14) was found to induce significant isotopic fractionation.     

Numerical simulation of partial discharge propagation in cable joints using the finite difference time domain method

In this second of a series of three papers, the authors investigate partial discharge (PD) detection and propagation in cable joints. The complex nature of cable joints leads to errors when PD analysis is carried out using conventional equivalent circuits. The authors use the finite difference time domain method to determine the transient electromagnetic fields caused by simulated PD in model cable joints.     

Cellulose dyeing parameters of 18 isomeric phenylazo-H-acid dyes containing two different reactive groups

Eighteen isomeric dyes, each based on phenylazo-H-acid and containing two reactive groups, namely a monochlorotriazine group and a sulphuric acid ester of ß-hydroxyethylsulphone, were applied to cotton fabric by an exhaustion process at 60d?C. The following properties were studied: spectra, uptake curves of the dyes before and after adding sodium carbonate, affinity, diffusion rate, and rates of hydrolysis and of reaction with cellulose, as evidenced by fixation and colour yield. Some significant correlations were found, but some missing or poor correlations indicated that there are further parameters or relationships between parameters that remain to be elucidated.     

A framework for application systems engineering

Interactive Application Systems (IAS) attend to the information needs of application experts, i.e. problem-solving end-users within particular application environments. As such, IAS must be customized functionally and behaviourally toward both user and environment. Such customizing must be feasible in an economical fashion. The study claims that this objective is met by appropriate IAS development tools and by a basic IAS architecture that consists of the following main building blocks: a general-purpose dialogue processor that is controlled by a particular user interface specification, called information net; a library of software modules and packages for providing system functions on the basis of reusable software; and a data management system that may, just like the library elements, be procured from outside, perhaps even including an already existing information base. The paper discusses the approach in detail with particular emphasis on information nets and on the integration of reusable software into a total system. The paper argues that the approach is flexible enough to accommodate (rapid) prototyping, i.e. procuring of first versions of an IAS, that may be used during requirements analysis to refine the user wishes, or operationally during an interim period until the final system becomes available.