Analysis Of Carbon Distribution Research Articles

Quantitative carbon distribution analysis of hydrocarbons, alcohols and carboxylic acids in a Fischer-Tropsch product from a Co/TiO2 catalyst during gas phase pilot plant operation

Comprehensive two-dimensional gas chromatography (GCxGC) analysis for 1-alcohols and gas chromatography–mass spectrometry (GC-MS) analysis for carboxylic acids, derivatised as their methyl esters, have been applied to liquid and wax Fischer-Tropsch (FT) hydrocarbon products. These methods in combination with conventional one-dimensional gas chromatography (GC) analysis of the aqueous, gaseous, liquid hydrocarbon and wax products plus conventional high-performance liquid chromatography (HPLC) analysis of the aqueous phase has allowed a quantitative distribution analysis of FT hydrocarbon and oxygenated products to be demonstrated for a Co/TiO2 catalyst operating in a fixed bed gas phase pilot plant utilising CANSTM catalyst carrier devices. The GC-MS method used is, to the best of our knowledge, the first application of this derivatisation route for the quantification of individual carboxylic acids in FT hydrocarbon product streams.Whilst the hydrocarbons and oxygenates that were identified are known compounds formed during the low temperature, Co catalysed, FT process the combination of the multiple analysis techniques used has allowed a level of detail to be gained on the product composition that is seldom reported.Additionally, 1H nuclear magnetic resonance spectroscopy (NMR) and 13C NMR analyses were used to quantify the average concentration of 1-olefin, cis- and trans-2-olefins, 1-alcohol and aldehyde as appropriate for the technique used. Comparison of GCxGC versus 1H NMR and GC-MS versus a KOH titration confirmed the applicability of the chromatographic methods for the quantitative analysis of FT oxygenated compounds. Long-chain 1-alcohols and carboxylic acids, ≥ C3, were found to be present at levels of 1/10th and 1/1000th that of hydrocarbons of equivalent carbon chain length respectively. The 1-olefin:n-paraffin ratio in the hydrocarbon liquid and wax products was found to decrease significantly with increasing carbon chain length and much more so than those of the 2-olefin or 1-alcohol.

Adenine in Viral mRNAs Manipulate the Carbon in Proteins

Protein s function is determined by the nature of carbon along its sequence. This carbon along the protein is determined by the nucleotides in the gene. The adenine in viral genetic material and carbon distribution along its proteins are the focus of this study. The results reveal that the presence of higher adenine content in viral material add adequate number of large number of hydrophobic residues in its proteins. The natural way of adding different sequences during development and evolution is better understood based on this carbon distribution analysis. Appropriate mutation that changes in carbon content and distribution in viral proteins might improve the functionality of the protein.

A Study of Diffusion- and Interface-Controlled Migration of the Austenite/Ferrite Front during Austenitization of a Case-Hardenable Alloy Steel

Migrating austenite/ferrite interfaces in the ferrite regions of an alloy steel, containing 0.20 wt pct C, 0.87 wt pct Mn, and 0.57 wt pct Cr, with a ferrite/pearlite microstructure have been observed during austenitization by a high-temperature confocal scanning laser microscope in order to determine the mechanisms of transformation. The samples were subjected to isothermal (790 °C to 850 °C) and nonisothermal (0.5 °C to 20 °C/s) temperature profiles. The kinetic rates extracted from the observations were compared to models for long-range diffusion-controlled and interface reaction-controlled migration. The transition between the two mechanisms was found to occur at T 0, which defines the temperature and composition at which a partitionless phase transformation is possible. Occurrence of the partitionless, interface-controlled transformation was confirmed by an analysis of carbon distribution and microstructure before and after a sample was subjected to a particular thermal profile. The mobility of such interfaces was found to be in the range 1.6·10−13 to 2·10−12 m4·J−1·s−1, which is consistent with previous studies on interface-controlled migration of the reverse reaction, α to γ, during cooling of dilute substitutional iron alloys. The diffusion-controlled migration, at temperatures below T 0, was found to occur in two stages: an initial stage, at which the growth rate can be predicted by a semi-infinite diffusion model; and a second stage, at which the growth slows more rapidly, possibly due to the overlap of diffusion fields.

Analysis of carbon distribution in rice plants grown at elevated CO2

Elevated CO2 increased the amount of photosynthate under high light condition. To examine the distribution of the photosynthate and its contribution to grain yield in rice plants grown at elevated CO2 condition (550ppm), we fed 13CO2 at some stages. In the plants fed 13CO2 at the vegetative stage, the distribution of 13C at 2 days after feeding, at the heading stage, and at harvesting time were not influenced by elevated CO2. On the other hand, in the plants fed 13CO2 at the heading stage, accumulation of 13C in the ear was accelerated, and 13C content in the whole plant and in the ear at harvest time were increased by elevated CO2. This tendency was also observed in the plants fed 13CO2 at the early and late grain filling stages. These results indicated that elevated CO2 increased not only photosynthesis but also transport of photosynthate to the sink. However, photosynthesis under low light condition and respiration in the plants grown at elevated CO2 were of no advantage to carbon storage. In conclusion, although the translocation to sink was increased by elevated CO2, total carbon assimilation per day might not be as high as was expected from photosynthesis under high light condition, so that grain yield might not be increased drastically.

Imaging and analysis of carbon distribution in GaAs using radioactive tracer 14C

Microscopic segregation of carbon in GaAs has been studied using autoradiography of a crystal doped with radioactive tracer 14C. The autoradiographs were compared to images of the wafers obtained by photoetching and by high resolution scanning photoluminescence microscopy. It was found that the carbon distribution is homogeneous within the limit of the resolution of the radiographs of about 15 μm and that there is no correlation between the carbon distribution and the luminescence contrast.