Silicon oxycarbonitride ceramic containing nickel nanoparticles from design to catalytic application

Nickel containing silicon oxycarbonitride ceramic nanocomposites are synthesized from hydrous nickel acetate and poly vinyl silazane Durazane 1800 or perhydropolysilazane NN120 20 A PHPS . A room temperature chemical reaction results in Ni containing polysilazane precursors which are transformed into ceramic nanocomposites with nickel nanoparticles 2 4 nm upon pyrolysis at elevated temperatures 700 1100 C under an argon atmosphere. The ceramic nanocomposites derived from the Durazane 1800 Ni precursor by the thermolysis process at 700 and 900 C manifest a microporous structure with a BET specific surface area of amp; 8764;361 and amp; 8764;232 m2 g amp; 8722;1, respectively. In contrast, all pyrolyzed samples derived from the PHPS Ni precursor exhibit a nonporous structure. The Ni SiOCN ceramic nanocomposites tested in a plug flow fixed bed reactor display significant catalytic activity in dry methane reforming to syngas. The highest CH4 reaction rate of 0.18 mol min amp; 8722;1 gNi amp; 8722;1 is observed at 800 C for the sample derived from the PHPS Ni precursor by pyrolysis at 900 C. All these make the materials developed in this work, i.e. nickel nanoparticles in situ formed in the SiOCN ceramic matrix, as promising candidates for heterogeneous catalysi

Simultaneous determination of blood concentrations of methohexital and its hydroxy metabolite by gas chromatography and identification of 4'-hydroxymethohexital by combined gas--liquid chromatography--mass spectrometry

A simple, sensitive and selective method is described for the simultaneous determination of low concentrations (less than 50 ng/ml) of underivatized methohexital and its hydroxy metabolite in small (0.1 ml) samples of human and rat plasma or whole blood by gas chromatography with nitrogen-selective detection. Moreover, the main metabolite in rat and man was identified as 4'-hydroxymethohexital by comparison of chromatograms from gas--liquid chromatography (GLC) with data obtained from GLC--mass spectrometry and 1H-nuclear magnetic resonance spectrometry of this metabolite, produced both by incubating methohexital with isolated rat liver microsomes and by isolating this metabolite from rat urine

Sex-specific effects of the Huntington gene on normal neurodevelopment

Huntington disease is a neurodegenerative disorder caused by a gene (HTT) with a unique feature of trinucleotide repeats ranging from 10 to 35 in healthy people; when expanded beyond 39 repeats, Huntington disease develops. Animal models demonstrate that HTT is vital to brain development; however, this has not been studied in humans. Moreover, evidence suggests that triplet repeat genes may have been vital in evolution of the human brain. Here we evaluate brain structure using magnetic resonance imaging and brain function using cognitive tests in a sample of school-aged children ages 6 to 18 years old. DNA samples were processed to quantify the number of CAG repeats within HTT. We find that the number of repeats in HTT, below disease threshold, confers advantageous changes in brain structure and general intelligence (IQ): the higher the number of repeats, the greater the change in brain structure, and the higher the IQ. The pattern of structural brain changes associated with HTT is strikingly different between males and females. HTT may confer an advantage or a disadvantage depending on the repeat length, playing a key role in either the evolution of a superior human brain or development of a uniquely human brain disease