Microbial transformations of selenite by methane-oxidizing bacteria

Abstract Methane oxidizing bacteria are well known for their role in the global methane cycle and their potential for microbial transformation of wide range of hydrocarbon and chlorinated hydrocarbon pollution. Recently, it has also emerged that methane-oxidizing bacteria interact with inorganic pollutants in the environment. Here we report what we believe to be the first study of the interaction of pure strains of methane-oxidizing bacteria with selenite. Results indicate that the commonly used laboratory model strains of methane oxidizing bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b are both able to reduce the toxic selenite (SeO32-) but not selenate (SeO42-) to red spherical nanoparticulate elemental selenium (Se0), which was characterised via EDX and EXAFS. The cultures also produced volatile selenium-containing species, which suggests that both strains may have an additional activity that can either transform Se0 or selenite into volatile methylated forms of selenium. Transmission electron microscopy (TEM) measurements and experiments with the cell fractions: cytoplasm, cell wall and cell membrane show that the nanoparticles are formed mainly on the cell wall. Collectively these results are promising for the use of methane-oxidizing bacteria for bioremediation or suggest possible uses in the production of selenium nanoparticles for biotechnology

Evidence-based Kernels: Fundamental Units of Behavioral Influence

This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behavior–influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior

Hydride generation-graphite furnace atomic absorption spectrometry: new prospects

Methods are described for the interference free determination of As and Se in seawater as well as marine tissues and sediments based on the generation of AsH3, and SeH2 using NaBH4 with subsequent trapping in a graphite furnace at 600\ub0 C. Calibration is achieved with simple aqueous working curves having sensitivities of 24\ub14 and 72\ub117 pg/0.0044 A for As and Se, respectively. Absolute detection limits of 30 pg As and 70 pg Se are estimated. Precision of determination is 2\u20133% for As and 5\u201310% for Se.NRC publication: Ye