Vibration-rotation pattern in acetylene. II. Introduction of Coriolis coupling in the global model and analysis of emission spectra of hot acetylene around 3 microns

This paper was selected by the editors of the Journal of Chemical Physics as one of the few of the many notable JCP articles published in 2009 that present ground-breaking research

Vibration-rotation pattern in acetylene: Introduction of Coriolis coupling in the global model and analysis of emission spectra of hot acetylene around 3 µm

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The investigation of mechanisms in environmental catalysis using time-resolved methods

The formation of nitrogen oxides (NOx) during a combustion process is difficult to avoid because of the large exotherm and the consequent problem of avoiding local high-temperature spikes. Consequently, for many applications, such as for automotive power generation, there will be a continuing need to use catalytic after-treatment to reduce harmful emissions. The investigation of the mechanisms of the key catalytic reactions in environmental catalysis can provide an insight into the action of the catalyst, and time-resolved methods offer a powerful means to study these processes under realistic conditions. The use of Temporal Analysis of Products (TAP) and Steady State Isotopic Transient Kinetic Analysis (SSITKA) methods to investigate the reduction of NOx under various experimental conditions is described. From a detailed analysis of the SSITKA profiles, it is shown that at low temperatures the mechanism for the formation of N-2 and N2O from NO may differ from the conventional high-temperature mechanism. This is supported by density functional theory calculations, which show that the barrier to the formation of N2O from the reaction of N(ads) and NO(ads) may be too high to allow this process to occur at low temperatures. The alternative reaction of NO(ads) + NO(ads) = N2O(g) + O(ads) is shown to be much more favorable and is consistent with the SSITKA analysis. The remarkable effect of hydrogen as a reductant at low temperatures is described, and alternative interpretations of the role of hydrogen are discussed.

Time-resolved studies of ultrafast wavepacket dynamics in hydrogen molecules

Recent advances in the study of quantum vibrations and rotations in the fundamental hydrogen molecules are reported. Using the deuterium molecules (D-2(+) and D-2) as exemplars, the application of ultrafast femtosecond pump-probe experiments to study the creation and time-resolved imaging of coherent nuclear wavepackets is discussed. The ability to study the motion of these fundamental molecules in the time-domain is a notable milestone, made possible through the advent of ultrashort intense laser pulses with durations on sub-vibrational (and sub-rotational) timescales. Quantum wavepacket revivals are characterised for both vibrational and rotational degrees of freedom and quantum models are used to provide a detailed discussion of the underlying ultrafast physical dynamics for the specialist and non-specialist alike. (C) 2009 Elsevier B.V. All rights reserved.

Development and validation of dry reagent time-resolved fluoroimmuno assays for zeranol and alpha-zearalenol to assist in distinguishing zeranol abuse from Fusarium spp. toxin contamination in bovine urine

Zeranol, an oestrogenic growth promoter in food animals, is banned within the European Union (EU). However, commercially available immunoassay kits for zeranol cross-react with toxins formed by naturally occurring Fusarium spp. fungi, leading to false-positive screening results. This paper describes the validation of a specificity enhanced, rapid dry reagent time-resolved fluoroimmunoassay (TR-FIA) for zeranol (recovery 99%, limit of detection 1.3 ng ml(-1)) demonstrating that up to 150 ng ml(-1) of Fusarium spp. toxins in urine do not lead to false-positive results. This assay will assist EU Member States to implement Council Directive 961 23\EC, which requires states to monitor for potential abuses of zeranol. A similar TR-FIA for the Fusarium spp. toxin a-zearalenol, using the same sample extract, is also described (recovery 68%, limit of detection 5.6 ng ml(-1)). Only the addition of diluted sample extract is required to perform these dry-reagent TR-FIAs, the results being available within 1 h of extract application. The EU-funded project 'Natural Zeranol' (FAIR5-CT97-3443) will use these fluoroimmunoassays to screen bovine urine in four Member States to gather data on the seasonality of Fusarium spp. toxin contamination of urine and the incidence of zeranol screening test positives.

A specificity-enhanced time-resolved fluoroimmunoassay for zeranol employing the dry reagent all-in-one-well principle

A simple dry chemistry time-resolved fluorescence immunoassay (TR-FIA) method was developed for the measurement of zeranol in bovine urine samples. The samples were purified by immunoaffinity chromatography and a specificity-enhanced zeranol antibody was employed in the immunoassay. This resulted in a highly selective method, which had only negligible reactivity with Fusarium spp, toxins. The all-in-one-well dry chemistry concept made the assay very simple to use because all the assay-specific reagents were already present in the reaction wells in dry form. Only the addition of diluted sample extract was required to perform the competitive one-step TR-FIA and the results were available in less than 1 h. The analytical limit of detection (mean + 3s) for the immunoassay was 0.16 ng ml(-1) (n=12) and the functional limit of detection for the whole method, estimated by the analysis of zeranol-free samples, was 1.3 ng ml(-1) (n=20). The recovery of zeranol at the level of 2 ng ml(-1) was 99% (n=18) and the within-assay variation ranged between 4.5 and 9.0%.