Feedback-amplified electrochemical dual-plate boron-doped diamond microtrench detector for flow injection analysis

An electrochemical flow cell with a boron‐doped diamond dual‐plate microtrench electrode has been developed and demonstrated for hydroquinone flow injection electroanalysis in phosphate buffer pH 7. Using the electrochemical generator‐collector feedback detector improves the sensitivity by one order of magnitude (when compared to a single working electrode detector). The diffusion process is switched from an analyte consuming “external” process to an analyte regenerating “internal” process with benefits in selectivity and sensitivity

Transmission of Novel Influenza A(H1N1) in Households with Post-Exposure Antiviral Prophylaxis

BACKGROUND: Despite impressive advances in our understanding of the biology of novel influenza A(H1N1) virus, little is as yet known about its transmission efficiency in close contact places such as households, schools, and workplaces. These are widely believed to be key in supporting propagating spread, and it is therefore of importance to assess the transmission levels of the virus in such settings. METHODOLOGY/PRINCIPAL FINDINGS: We estimate the transmissibility of novel influenza A(H1N1) in 47 households in the Netherlands using stochastic epidemic models. All households contained a laboratory confirmed index case, and antiviral drugs (oseltamivir) were given to both the index case and other households members within 24 hours after detection of the index case. Among the 109 household contacts there were 9 secondary infections in 7 households. The overall estimated secondary attack rate is low (0.075, 95%CI: 0.037-0.13). There is statistical evidence indicating that older persons are less susceptible to infection than younger persons (relative susceptibility of older persons: 0.11, 95%CI: 0.024-0.43. Notably, the secondary attack rate from an older to a younger person is 0.35 (95%CI: 0.14-0.61) when using an age classification of <or=12 versus >12 years, and 0.28 (95%CI: 0.12-0.50) when using an age classification of <or=18 versus >18 years. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the overall household transmission levels of novel influenza A(H1N1) in antiviral-treated households were low in the early stage of the epidemic. The relatively high rate of adult-to-child transmission indicates that control measures focused on this transmission route will be most effective in minimizing the total number of infections

Biodegradation of liquid scintillant cocktails

This study considers the use of biodegradation as an alternative means of waste disposal for two common liquid scintillant cocktail types. EcoSafeTM and Gold StarTM.Sequencing batch reactors were used containing activated sewage sludge (ASS) as a biomass source, a standard nutrient medium and a carbon source in the form of LS cocktail or one of its components. Compounds of interest were butoxyethoxy ethanol (BEE), di-isopropyl naphthalene (DIPN), branched alkyl benzenes (BABs), 2,5-diphenyl oxazole (PPO), bis-(o-methylstyryl benzene (bis-MSB) and nonylphenol ethoxylates (NPEs). All experiments were conducted under laboratory conditions with no temperature, pressure or light controls. Aeration was used to ensure aerobic conditions and mixing.Due to analytical limitations, compound concentrations were only determined for BEE, DIPN, BABs and PPO. Bis-MSB and NPEs were not assessed. Both biotic and abiotic losses were quantified at a compound concentration level equal to that present in a 1 % LS cocktail solution. Losses were found for BEE and PPO, which were primarily attributable to biomass increases and therefore biodegradation. Some abiotic losses were also evident. DIPN showed no biotic or abiotic losses under the conditions used. This contradicts the outcomes of other studies which showed that biodegradation did occur, albeit at much lower levels (0.005 %). The sixteen BAB isomers were grouped according to the length of their shorter alkyl chain. It was evident that selective losses were occurring as a function of this chain length. Those with one or two atoms in their aliphatic chain showed large abiotic and biotic losses. With increased chain length compound losses were reduced, particularly regarding biotic losses. Degradation rates were calculated by first order rate equations. Both lag time and degradation rate were directly related to compound recalcitrance. The experimental technique did not allow for the detection of degradation products. Despite limited control of degradation conditions, and the use of fresh activated sewage sludge for each experiment, the extent of compound loss was shown to be reproducible.A commercial viability investigation and the basis for an environmental impact assessment were included in this study.</p

Exploring effects of intermittent light upon visible light promoted water oxidations

Visible light promoted photocatalytic water oxidations for potential solar fuel production have been studied widely, with many reports on optimization of reagent components. Here we report an exploration on the effects upon ongoing reactions of daylight equivalent light intensity illumination with regulated short dark periods of a few seconds duration as compared to standard continuous illumination. Comparison was made with systems employing synthesized low cost earth abundant iron oxide, calciumoxomanganite and cobalt oxide nanoparticulate catalysts together with a [Ru(bpy)3]2+ light harvesting dye and an electron acceptor. Yields of gaseous O2 and proton production were measured in situ and in real time. The study found that low cost catalysts could give very significantly increased O2 yields, turn over frequency and improved reaction profiles by use of simple on/off illumination. A range of timings with identical overall photon flux were tested and an optimum determined. Analysis of effects upon the light sensitizer under the range of lighting conditions (through mass spectrometry and UV-vis measurements), together with implementation of a continuous flow system as comparison to the batch reactions, were all employed to help elucidate the mechanisms for the clear improvements in reaction yields observed. These are believed to stem from reduction in self-decomposition of excess oxidized sensitizer and better synchronization of cyclic sensitizer oxidation/reductions with water oxidation at the metal oxide surface at specific light on?:?off timing

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Visible light promoted photocatalytic water oxidations for potential solar fuel production have been studied widely, with many reports on optimization of reagent components. Here we report an exploration on the effects upon ongoing reactions of daylight equivalent light intensity illumination with regulated short dark periods of a few seconds duration as compared to standard continuous illumination. In addition raw XRD data of metal oxide catalysts used, an additional image of reaction flask and a movie file that shows a reaction flask under under cycling RGB LED illumination is given here