Simultaneous and sequential adsorption of deuterium and nitrous oxide by rhenium

The addition of nitrous oxide to a stream of deuterium passing over a rhenium filament reduced the initial sticking probability of the latter gas from 0.24 to 0.09 when the proportion of N₂O exceeded 40%. For the addition of deuterium to nitrous oxide the equivalent figures were 0.45 and 0.30 when deuterium exceeded 30% of the gas phase. These results are attributed to a competition between the two gases for places in the precursor state on the surface. The replacement of adsorbed deuterium from a saturated layer by the oxygen atom of nitrous oxide proceeded initially with a high probability, 0.27, at room temperature and with each oxygen atom replacing one deuterium atom. However, the reaction was incomplete, about 2 × 10¹⁴ atoms cm^?2 of deuterium remaining on the surface. It is suggested that kinetic rather than thermodynamic factors are responsible for the incomplete reaction, possibly as the result of a high activation energy for the migration of deuterium atoms over an oxygenated rhenium surface.     

Automated, fluorescence-based approach for the specific diagnosis of chicken coccidiosis.

We have established a fluorescence-based electrophoretic approach for the specific identification of all seven currently recognised species of Eimeria infecting chickens. The second internal transcribed spacer (ITS-2) of ribosomal DNA is amplified by polymerase chain reaction (PCR) from any of the seven species using a single set of oligonucleotide primers (of which the reverse one is fluorescently labelled). The amplicons are heat-denatured, subjected to denaturing polyacrylamide gel electrophoresis in a 377 DNA sequencer (ABI). The chromatograms produced are stored electronically and then analysed using GeneScan 3.1 software. Using control DNA samples representing monospecific lines of Eimeria, regions in the chromatograms have been defined for the specific identification of each of the seven species, although some variation in the chromatograms (reflecting population variation) was detectable within two species. Electrophoretic reading and analysis is carried out automatically using a computer imaging system, thus making it a time- and cost-effective approach. It is well suited for high-throughput diagnostic screening of oocyst samples and should find applicability as a tool for prevalence studies, monitoring of coccidiosis outbreaks and the quality control of vaccines.     

Separation of Cesium from Intermediate Level Waste Solutions Using Zirconyl Tungstate Ceramic-Supported Membranes

Zirconyl tungstate ceramic-supported membranes were developed and characterized. The transport process of Cs(I), Sr(II) and La(III) from the anode compartment to the cathode was investigated. The cationic fluxes for Cs(I), Sr(II) and La(III) were found to be 9·10^–10, 2.7·10^–9 and 2.4·10^–9 g·eq·cm^–2·s^–1, respectively. The transport numbers of these cations were found to be 0.12, 0.07 and 0.09, respectively. Separation of Cs(I), Sr(II) and La(III) was achieved using EDTA as a chelating agent in the anode compartment. Cs(I) was successfully separated with a decontamination factor of 97% from simulated intermediate level liquid waste (ILLW) containing Cs(I) and Sr(II).     

On the influence of aggressive driving behavior on the dynamics of traffic flow

The car following model under discussion is a system of ordinary differential equations describing N cars moving around a circular road. We extend the stability analysis of the model in two directions: variable reaction time (depending on the headway) and an additional part describing the aggressive driving tendency. We study the global bifurcation dynamics and in particular its dependence on these two new ingredients. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Spin waves of a layered ferromagnetic electron gas

Using a first-order Green's function technique, the spin wave spectrum of a layered ferromagnetic electron system is determined in the long-wave length limit. It is shown that the spin wave stiffness is a highly anisotropic quantity. A discussion of the Stoner-Overhauser-Wohlfarth condition shows that both electron tunneling processes and a more sophisticated expression of the Coulomb interaction matrix element than the usual Hubbard form are important for the existence of ferromagnetic ordering.     

Reliability-Based Optimization of structural systems

A method to carry out a Reliability-Based Optimization (RBO) of especially nonlinear structural systems is introduced. Statistical uncertainties involving both structural and loading properties are considered. The concept is based on the separation of structural reliability analyses and the optimization procedures. Two approaches are discussed, depending on the interaction of reliability analysis and mathematical programming and the way of representation of the limit state functions (LSF) of the structure. As, for cases of practical significance, the LSF is known only pointwise it is approximated by Response Surfaces (RS). For the response calculations Finite Element (FE) procedures are utilized. Failure probabilities are determined by applying variance reducing Monte Carlo simulation (MCS) techniques such as Importance Sampling (IS). Following the reliability analysis, the optimization procedure is controlled by the NLPQL algorithm. A numerical example in terms of a template ocean platform exemplifies the procedures.Formerly Institute of Engineering Mechanics, Leopold-Franzens-University, Innsbruck, Austria     

Towards Platinum(II) Complexes for in cellulo Applications: Synthesis,Characterization, Biological and Catalytic Evaluation

With the aim of achieving bioorthogonal intracellular catalysis, a library of platinum(II) complexes was synthesized. Their non-toxicity to living cells was demonstrated and their catalytic activity was evaluated on a cyclization reaction leading to a highly fluorescent coumarin. None of the platinum complexes showed any catalytic activity for coumarin synthesis. Still, we demonstrated that the silver salt AgSbF₆ commonly used to ‘activate’ metal catalysts by removing a chloride is a very efficient catalyst for the studied intramolecular cyclization reaction.     

Synthesis of a ferrocenyl uracil PNA monomer for insertion into PNA sequences

The deprotection of the tert-butyl group of a ferrocenyl uracil Peptide Nucleic Acid (PNA) monomer, Fmoc-aeg(R)-O^tBu (1) was achieved using a two step synthesis involving hydrolysis in basic conditions to give first the zwitterion of ⁺NH₃-aeg(R)-O⁻ (7). Compound 7 was reacted in situ with N-(9-fluorenylmethoxycarbonyloxy)succinimide to obtain the expected compound Fmoc-aeg(R)-OH (2) (Abbreviations: Aeg = (2-aminoethyl)-glycine; Fmoc = 9-fluorenylmethoxycarbonyl; O^tBu = tert-butyl; R = 5-(N-ferroce-nylmethylbenzamido)uracyl).