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The neutron capture cross section of 185Re was measured in the astrophysically important energy region. Measurements were made using a neutron beam from a 7Li(p,n)7Be neutron source with energies ranging from 3 to 90 keV. Two different experimental techniques, time-of-flight (TOF) and activation methods, were employed. In the TOF experiments, the total neutron capture cross section of 185Re was determined by the pulse-height weighting technique. In the activation method, the partial capture cross section leading to the ground state of 186Re was measured by detecting decay γ-rays from neutron activated samples. The present cross section values were compared with evaluated cross section data and previous measurements. The difference between the TOF and activation results was smaller than experimental uncertainties. This suggests that the production cross section of isomer states of 186Re is very small.

The fate (stability, multiplication) of S. aureus, E. coli and E. faecalis was determined in three classes of recreational waters (seawater, estuarine, stream) supplemented with nutrients in the form of sewage and peptone. In the absence of sunlight (24 ± 2 °C), all bacteria in all water samples did not multiply and were slowly (days) inactivated. When 50% sewage was added to all water samples, E. coli and E. faecalis multiplied but S. aureus did not. When peptone (0.05%, 0.5%) was the added nutrient, the three bacteria multiplied. In the presence of sunlight (15–27 °C), S. aureus was inactivated rapidly (hours) in all water samples. These results show that when their nutritional requirements are met, S. aureus, E. coli and E. faecalis can multiply in the high salinity conditions of seawater. However, under environmental conditions, sunlight is an effective natural bactericidal agent. [ABSTRACT FROM AUTHOR]

Standard PCR (SPCR) and quantitative PCR (QPCR) assays using primers for general and for human-specific Bacteroides 16S rRNA markers were selected as the molecular tests to assess sewage contamination in recreational waters of Hawaii and these same water samples were assayed for culturable concentrations of selected faecal microbial indicators. The results of this study showed that the general primer for Bacteroides was not useful because ambient and polluted water samples were positive for this marker. However, use of human-specific primers reliably detected sewage contamination. The human-specific Bacteroides detection data supported previously reported conclusions that concentrations of alternative faecal indicators (C. perfringens, FRNA coliphages) but not traditional faecal indicators (faecal coliform, E. coil, enterococci) are reliable indicators of faecal contamination in Hawaii's environmental waters. The QPCR assay for the human-specific Bacteroides 16S rRNA marker was faster, more sensitive and more reliable than comparable SPCR assay because QPCR assay provided additional information such as melting temperatures, which confirmed that the right amplicons were being measured and Ct values, which indicated the relative level of faecal contamination. [ABSTRACT FROM AUTHOR]

Aluminum reflectors were added to solar units designed to inactivate faecal microorganisms (faecal coliform, E. coli, enterococci, FRNA coliphage, C. perfringens) in stream water and diluted sewage by the two mechanisms (solar heat, solar UV) known to inactivate microorganisms. During sunny conditions, solar units with and without reflectors inactivated E. coli to <1 CFU/100 ml to meet drinking water standards. Solar units with reflectors disinfected the water sooner by increasing the water temperature by 8-10°C to 64-75°C. However, FRNA coliphages were still detected in these samples, indicating that this treatment may not inactivate pathogenic human enteric viruses. During cloudy conditions, reflectors only increased the water temperature by 3-4°C to a maximum of 43-49°C and E. coli was not completely inactivated. Under sunny and cloudy conditions, the UV wavelengths of sunlight worked synergistically with increasing water temperatures and were able to disinfect microorganisms at temperatures (45-56°C), which were not effective in inactivating microorganisms. Relative resistance to the solar disinfecting effects were C. perfringens > FRNA coliphages > enterococci > E. coli > faecal coliform. [ABSTRACT FROM AUTHOR]