Development of a class-specific ELISA for sulfonylurea herbicides (sulfuron screen)

The development of a direct competitive ELISA for the detection of a broad range of sulfonylurea herbicides (SUs) is described. Polyclonal antibodies were generated in rabbits using three different immunizing haptens. Antiserum with the broadest specificity was obtained with a mesosulfuronbenzylamine derivative which was coupled via a succinic acid spacer to keyhole limpet hemocyanine. A heterologous enzyme tracer which did not contain the succinic acid bridge was prepared using activated horseradish peroxidase. The direct competitive ELISA was optimized and applied for spiked tap and surface water samples. From 30 SUs, 8 compounds showed a molar cross-reactivity (CR) higher than 100% (this value was set for the hapten) and 11 compounds CRs between 10% and 100%. The ELISA can detect 16 SUs at a concentration of 0.1 microg/L or lower. Different surface and tap water samples were spiked with chlorimuron ethyl, metsulfuron methyl, or primisulfuron methyl at concentrations of 100, 200, or 500 ng/L and subsequently analyzed by both ELISA and HPLC-UV. Correlation analysis revealed good agreement between both methods (r2 = 0.983/0.948/0.982; n = 21 for each analyte). Using ELISA, no sample pretreatment other than filtration was necessary.     

Zyklisches Kriechen des Vergütungsstahles 42 CrMo4 unter mittelspannungs-behafteter Zug-Druck-Wechselbeanspruchung bei Raumtemperatur

Kraftkontrollierte Zug-Druck-Wechselversuche an vergütetem Stahl 42 CrMo4. Ermittlung von Wechselverformungs- und Mitteldehnungskurven bei unterschiedlichen Kombinationen von Mittelspannung und Spannungsamplitude unter Raumtemperaturbedingungen. Konsequenzen für übliche Dauerfestigkeitsschaubilder.     

MLMIN: A multicore processor and parallel computer network topology for multicast

In future, multicore processors with hundreds of cores will collaborate on a single chip. Then, more advanced network-on-chip (NoC) topologies will be needed than today's shared busses for dual core processors. Multistage interconnection networks, which are already used in parallel computers, seem to be a promising alternative. In this paper, a new network topology is introduced that particularly applies to multicast traffic in multicore systems and parallel computers. Those multilayer multistage interconnection networks are described by defining the main parameters of such a topology. Performance and costs of the new architecture are determined and compared to other network topologies. Network traffic consisting of constant size packets and of varying size packets is investigated. It is shown that all kinds of multicast traffic particularly benefit from the new topology.     

Application-Layer Traffic Analysis of a Peer-to-Peer System

Characterizing traffic behavior helps to optimize the network architecture for improved performance. Using a modified LimeWire servent (for both the server and client) and a variance-time plot for traffic characterization, the authors analyze the Gnutella protocol's traffic shape and find that the messages exhibit a self-similar shape. This result shows network designers that they need to consider the self-similar traffic shape in their set-up — for instance, by introducing appropriate buffer sizes.     

Transient and steady-state analysis of catalyst poisoning and mixed potential formation in direct methanol fuel cells

The present dynamic model is developed to investigate the coupled reaction mechanisms in a DMFC and therein associated voltage losses in the catalyst layers. The model describes a complete five-layer membrane electrode assembly (MEA), with gas diffusion layers, catalyst layers and membrane. The analysis of the performance losses are mainly focused on the electrochemical processes. The model accounts for the crossover of both, methanol from anode to cathode and oxygen from cathode to anode. The reactant crossover results in parasitic internal currents that are finally responsible for high overpotentials in both electrodes, so-called mixed potentials. A simplified and general reaction mechanism for the methanol oxidation reaction (MOR) was selected, that accounts for the coverage of active sites by intermediate species occurring during the MOR. The simulation of the anode potential relaxation after current interruption shows an undershoot behavior like it was measured in the experiment [1]. The model gives an explanation of this phenomenon by the transients of reactant crossover in combination with the change of CO and OH coverages on Pt and Ru, respectively.     

Durability of Brick Lined Steel Ladles from a Mechanical Point of View

The refractory lining in steel ladles is exposed to chemical and mechanical loads during the heats. Mechanical loads develop from the thermal expansion of the refractories which is confined either by the steel construction or by regions of different temperature within the refractory material. The aim of this work was the investigation of factors influencing the mechanical durability of refractory steel ladle linings and the clarification of failure mechanisms. Especially irreversible strains at the hot face of the working lining caused by compressive stresses induce an opening of joints at the hot face. The irreversible strains reduce the compressive stresses in circumferential direction and increase the probability of tensile failure. A further effect of the irreversible strains is a reduced stability of the working lining. Of special interest in this context is a possible controlled expansion of bricks to counterbalance the irreversible compressive strains.     

A new load cell for measuring normal and shear stresses

A special stress measuring device for determining the normal and shear stresses acting on silo walls was developed and tested. The load cell can be used for measuring simultaneously the normal stress as well as the intensity and direction of the shear stress.     

Phase Transformation Modelling and Parameter Identification from Dilatometric Investigations

The goal of this paper is to propose a new approach towards the evaluation of dilatometric results, which are often employed to analyse the phase transformation kinetics in steel, especially in terms of continuous cooling transformation (CCT) diagram. A simple task of dilatometry is deriving the start and end temperatures of the phase transformation. It can yield phase transformation kinetics provided that plenty metallographic investigations are performed, whose analysis is complicated especially in case of several coexisting product phases. The new method is based on the numerical solution of a thermomechanical identification problem. It is expected that the phase transformation kinetics can be derived by this approach with less metallographic tasks. The first results are remarkably promising although further investigations are required for the numerical simulations.