Inhibition of Bacterial Adherence on the Surface of Stents and Bacterial Growth in Bile by Bismuth Dimercaprol

Bacterial infection and biofilm formation on the surface of biliary stents is believed to be one of the main factors in stent occlusion. This study explored the role of the new reagent, bismuth dimercaprol, in preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stents. Sterile porcine bile preparations, infected separately with Escherichia coli, Klebsiella pneumoniae, Enterobacter , and Enterococcus , were used as the perfusion media in an in vitro perfusion system. The bacterial growth in the media and the bacterial adherence on the surface of stents were tested when different concentrations of bismuth dimercaprol were used in the perfusion media. BisBAL (5 μ M ) did not inhibit the growth of any of the tested bacterial species. It did, however, significantly decrease the amount of bacteria adhering to the surface of stents for all bacterial strains except Escherichia coli . Bismuth dimercaprol (20 μ M ) significantly inhibited the growth of Escherichia coli, Klebsiella pneumoniae , and Enterobacter and, thereby, significantly decreased the amount of these bacteria adhering to the surface of stents. The unique bactericidal and anitbiofilm activities of bismuth thiols might contribute to delaying the process of biliary stent occlusion if the effective concentrations of bismuth thiols could be delivered to the target sites. The feasibility of this application of bismuth thiols deserves further investigation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44439/1/10620_2005_Article_2702.pd

Distinguishing fissions of 232Th, 237Np and 238U with beta-delayed gamma rays

Measurements of beta-delayed gamma-ray spectra following 14-MeV neutron-induced fissions of Th, U, and Np were conducted at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Spectra were collected for times ranging from 1 min to 14 h after irradiation. Intensity ratios of gamma-ray lines were extracted from the data that allow identification of the fissioning isotope.© 2013 Elsevier B.V. All rights reserved. 232 238 23

Determining the [superscript 239]Np(n, f ) cross section using the surrogate ratio method

Publisher's version/PDFBackground: Neutron-induced fission cross-section data are needed in various fields of applied and basic nuclear science. However, cross sections of short-lived nuclei are difficult to measure directly due to experimental constraints. Purpose: The first experimental determination of the neutron-induced fission cross section of [superscript 239]Np at nonthermal energies was performed. This minor actinide is the waiting point to [superscript 240]Pu production in a nuclear reactor. Method: The surrogate ratio method was employed to indirectly deduce the [superscript 239]Np(n, f) cross section. The surrogate reactions used were [superscript 236]U([superscript 3]He, p) and [superscript 238]U([superscript 3]He, p) with the reference cross section given by the well-known [superscript 237]Np(n, f ) cross section. The ratio of observed fission reactions resulting from the two formed compound nuclei, [superscript 238]Np and [superscript 240]Np,was multiplied by the directly measured [superscript 237]Np(n, f ) cross section to determine the [superscript 239]Np(n, f ) cross section. Results: The [superscript 239]Np(n, f ) cross section was determined with an uncertainty ranging between 4% and 30% over the energy range of 0.5–20 MeV. The resulting cross section agrees closest with the JENDL-4.0 evaluation. Conclusions: The measured cross section falls in between the existing evaluations, but it does not match any evaluation exactly (with JENDL-4.0 being the closest match); hence reactor codes relying on existing evaluations may under- or overestimate the amount of [superscript 240]Pu produced during fuel burnup. The measurement helps constrain nuclear structure parameters used in the evaluations

Distinguishing fissions of 232Th, 237Np and 238U with beta-delayed gamma rays

Measurements of beta-delayed gamma-ray spectra following 14-MeV neutron-induced fissions of 232Th, 238U, and 237Np were conducted at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Spectra were collected for times ranging from 1 min to 14 h after irradiation. Intensity ratios of gamma-ray lines were extracted from the data that allow identification of the fissioning isotope.© 2013 Elsevier B.V. All rights reserved