Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
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3 records were found.
The molecular composition of five brown coals from three different basins (Maestrazgo, Mequinenza and Rubielos) in Spain was investigated by flash pyrolysis-gas chromatography and flash pyrolysis-gas chromatography-mass spectrometry. In these techniques, the macromolecular material is thermally degraded in an inert atmosphere and the compounds formed are on-line separated, identified and quantified. This information provided insight into the macromolecular structure of the coals which was inaccesible by other means. The composition of the pyrolysates is described in detail with emphasis on the distributions and relative abundance of n-alkanes, n-1-alkanes, (alkyl)phenols, sulphur compounds [(alkyl)thiophenes and (alkyl)benzenes and (alkyl)naphthalenes. These compound classes represent the major pyrolysis products of the samples analyse...
The kerogens of three Tertiary Catalan lacustrine oil shales were analyzed by light microscopy, flash pyrolysis-gas chromatography-mass spectrometry, and bulk composition methods (elemental analysis, Rock Eval pyrolysis). Two of the three kerogens (Ribesalbes and Campins) are extremely rich in organic sulphur (atomic Sorg/C ratio > 0.04) and hydrogen (atomic ratio H/C ratio > 1.5) and are, consequently, classified as Type I-S kerogens. Very characteristic distribution patterns of flash pyrolysis products (e.g., alkan-9- and -10-ones, alkadienes) of the Ribesalbes kerogen revealed that it is predominantly composed of fossilized organic matter of the freshwater alga Botryococcus braunii. These two findings demonstrate that sulphurization of organic matter may also occur in lacustrine sediments provided that sulphate is supplied by extern...
A study of the solvent extracts of four samples from two immature oil shales from Tertiary lacustrine basins, Ribesalbes and Campins (southern European rift system), deposited under reducing conditions, has allowed the identification of S-containing hopanoids and novel highly branched isoprenoids (HBI). HBI derivatives occur only in the Ribesalbes shales where two new structural types of C25 S-containing HBI isomers have been identified. These compounds probably have different precursor organisms from those in recent marine systems. They are present as thiophenes, thiolanes and thiolane sulphoxides in one case and only as thiolanes in the other. 17,21(H)-, 17,21(H)- and 17,21(H)-thienyl- and methylthienylhopanes have been found in the shales from the two basins. In the Campins samples these compounds occur together with thiolanyl- and ...
