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A solvent extraction method was used to determine the stability constants of Np(V) complexes with fluoride and sulfate in 1.0M NaClO4 from 25 to 60 °C. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of fluoride and sulfate were increased. Stability constants of the 1 : 1 Np(V)-fluoride complexes and the 1 : 1 Np(V)-sulfate and 1 : 2 Np(V)-sulfate complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [F-] and [SO4 2-] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures by using the Van't Hoff equation.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Douglas, J. Friese, G. Warren, P. Bachelor, O. Farmer, A. Choiniere, S. Schulte and C. Aalseth


A project has been undertaken at Pacific Northwest National Laboratory (PNNL) to tailor a series of efficient chemical separations to allow the rapid quantification of gamma-ray emitting isotopes in mixed fission product (MFP) samples. In support of that goal, modeling of singles and coincident gamma-ray spectra that would result from various chemical separation strategies has been performed. These simulated spectra have identified likely instances of spectral interference and have provided an estimate of the time window available for the detection of radionuclides following various chemical separation schemes. A description of results to date is presented here, demonstrating the utility of this approach for improved processing and analysis of fission product samples.

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Carvacrol, a primary constituent of plant essential oils (EOs), and its antimicrobial activity have been the subject of many in vitro studies. Due to an increasing demand for alternative antimicrobials and an emerging number of antibiotic resistant bacteria, the use of essential oils has played a major role in many recent approaches to reduce Campylobacter colonization in poultry before slaughter age. For that purpose, the reducing effect of carvacrol on Campylobacter jejuni prevalence in broilers was determined in vivo in an experimental broiler chicken model during an entire fattening period. Carvacrol was added to the feed in a concentration of 120 mg/kg feed four days post hatch until the end of the trial. In this study, we demonstrated a statistically significant decrease of C. jejuni counts by 1.17 decadic logarithm (log10) most probable number (MPN)/g in cloacal swabs during starter and grower periods (corresponding to a broilers age between 1 and 28 days). Similar results were observed for colon enumeration at the end of the trial where C. jejuni counts were significantly reduced by 1.25 log10 MPN/g. However, carvacrol did not successfully reduce Campylobacter cecal colonization in 33-day-old broilers.

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