The Spacecraft Maximum Allowable Concentrations (SMACs) for C2-C9 alkanes set by NASA in 2008 under the guidance and approval of the National Research Council specifically excluded SMACs for n-hexane. Unlike other C2-C9 alkanes, n-hexane can cause polyneuropathy after metabolism in humans or rodents and so requires more stringent SMACs than the other members of this group do. This document reviews the relevant published studies of n-hexane toxicity to develop exposure duration-specific SMACs for n-hexane of 200 ppm for 1 hour, 30 ppm for 24 hours, and 2.4 ppm for 7 days, 30 days, 180 days, and 1000 days.
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The Spacecraft Maximum Allowable Concentrations (SMACs) for C2-C9 alkanes set by NASA in 2008 under the guidance and approval of the National Research Council specifically excluded SMACs for n-hexane. Unlike other C2-C9 alkanes, n-hexane can cause polyneuropathy after metabolism in humans or rodents and so requires more stringent SMACs than the other members of this group do. This document reviews the relevant published studies of n-hexane toxicity to develop exposure duration-specific SMACs for n-hexane of 200 ppm for 1 hour, 30 ppm for 24 hours, and 2.
View Article and Find Full Text PDFGas-Phase Reactions of Atomic Gold Cations with Linear Alkanes (C2-C9).
J Phys Chem A
June 2016
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
To develop proper ionization methods for alkanes, the reactivity of bare or ligated transition metal ions toward alkanes has attracted increasing interests. In this study, the reactions of the gold cations with linear alkanes from ethane up to nonane (CnH2n+2, n = 2-9) under mild conditions have been characterized by mass spectrometry and density functional theory calculations. When reacting with Au(+), small alkanes (n = 2-6) were confirmed to follow specific reaction channels of dehydrogenation for ethane and hydride transfer for others to generate product ions characteristic of the original alkanes, which indicates that Au(+) can act as a reagent ion to ionize alkanes from ethane to n-hexane.
View Article and Find Full Text PDFGrowth of a non-methanotroph on natural gas: ignoring the obvious to focus on the obscure.
Environ Microbiol Rep
October 2009
Departments of Biochemistry and Biophysics, Microbiology and Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
Methanotrophs are well known for their ability to grow on methane in natural gas environments; however, these environments also contain low concentrations of longer-chain-length gaseous alkanes. This mixture of alkanes poses a problem for organisms that might otherwise grow on alkanes ≥ C2 because methane could inhibit oxidation of growth substrates and lead to an accumulation of toxic C1 metabolites. Here, we have characterized the growth of a C2 -C9 alkane-utilizing bacterium, Thauera butanivorans, in conditions containing high concentrations of methane and small amounts (< 3% of total alkane) of C2 -C4 .
View Article and Find Full Text PDFThauera butanivorans sp. nov., a C2-C9 alkane-oxidizing bacterium previously referred to as 'Pseudomonas butanovora'.
Int J Syst Evol Microbiol
July 2009
Department of Botany and Plant Pathology, 2082 Cordley Hall, Oregon State University, Corvallis, OR 97331-2902, USA.
The placement of 'Pseudomonas butanovora' in the genus Thauera was proposed previously, based on 16S rRNA gene sequence analysis, upon further studies of taxonomical characteristics. In this study, physiological characteristics and DNA-DNA reassociation data are presented and the transfer of 'P. butanovora' to the genus Thauera is proposed.
View Article and Find Full Text PDFSimultaneous determination of mono- and dicarboxylic acids, omega-Oxo-carboxylic acids, midchain ketocarboxylic acids, and aldehydes in atmospheric aerosol samples.
Environ Sci Technol
October 2005
Department of Chemistry, Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong.
This paper describes a method for the simultaneous determination of monocarboxylic acids (C6-C34), dicarboxylic acids (C2-C24), omega-oxo-carboxylic acids (C2-C9), ketocarboxylic acids (pyruvic and pinonic acid), and select aldehydes (glyoxal, methylglyoxal, and nonanal) in atmospheric particles. Quantification of these compounds gives information on important chemical characteristics of aerosols for source apportioning of aerosol organics and for studying atmospheric processes leading to secondary organic aerosol formation. These target analytes were determined as their butyl ester or butyl acetal derivatives using gas-chromatography mass spectrometry.
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