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At least 19 recordsLinked to original sources
PubMed1992

Polymorphism of a long-chain cycloparaffin (CH2)120.

The polymorphism of a long-chain cycloparaffin (CH2)120 and chain packing in its crystals were discussed on the basis of some results obtained mainly by transmission electron microscopy. Monoclinic and orthorhombic single crystals of (CH2)120 were isothermally grown together from a dilute solution in p-xylene. Lozenge-shaped orthorhombic single crystals were more frequently observed than lath-shaped monoclinic ones. The basal surfaces of orthorhombic and monoclinic single crystal platelets were decorated with vapor-deposited polyethylene [PE]. Orthorhombic single crystals of (CH2)120 with the (110) twin boundary and monoclinic ones with the (100) twin boundary were also observed. Rod-like edge-on crystals of (CH2)120 were grown from a dilute p-xylene solution onto the (001) surface of alkali halides. The crystal system of the (CH2)120 edge-on crystals depended on the kind of substrate. The monoclinic crystal was grown on NaCl, the orthorhombic one on KBr and KCl. The monoclinic form of (CH2)120 edge-on crystal was transformed to the orthorhombic one by annealing on NaCl. In both monoclinic and orthorhombic edge-on crystals, the molecular plane determined by two zigzag stems in a molecule of (CH2)120 was parallel to the substrate surface and the molecular axis (crystallographic c-axis) was perpendicular to the longer side of the rod-like edge-on crystals. The sub-cell dimensions of the stem chains in both forms of (CH2)120 crystals were very similar to those of monoclinic and orthorhombic PE crystals, respectively.

Crystallization↗
PubMed1974

Microbial degradation and assimilation of n-alkyl-substituted cycloparaffins.

Studies were conducted on the oxidation and assimilation of n-alkyl-substituted cycloalkane substrates by several hydrocarbon-utilizing microorganisms. These microorganisms utilized heptadecylcyclohexane and dodecylcyclohexane as the sole source of carbon and energy. Neither methylcyclohexane nor ethylcyclohexane was utilized as a growth substrate by any organisms tested. Gas-liquid chromatographic analyses of fatty acids present in cells after growth on dodecylcyclohexane confirm direct incorporation of both alpha- and beta-oxidation products. Growth patterns of these organisms on n-alkyl-substituted cyclohexane fatty acids of varying chain lengths suggest a greater probability of ring cleavage when the side chain contains an odd number of carbons.

Biodegradation, Environmental↗
PubMed1977

[Oxidation of a naphthenic hydrocarbon, dodecylcyclohexane, in the rat].

Naphthenic hydrocarbons, mainly of fossil origin, are widespread in our environment, and contaminate the food chains; they are also used as food additives. Their fate in mammals is unknown, except for the fact that they are absorbed and accumulate in tissues. Only a few microorganisms have been shown capable or oxidising n-alkyl substituted cycloparaffins. In this study, dodecylcylohexane has been chosen as a typical monocycloparaffin, and has been administered orally to rats. The GLC and GLC-MS analysis of the methylesters of body and hepatic fatty acids led to the identification of cyclohexyldodecanoic and its decanoïc and octanoïc homologs. The alkyl chain undergoes a terminal oxidation followed by the classical beta-oxidation process. After administration of one 200 mg dose, or incorporation of 0.1% of the cycloparaffin in the diet for 2 months, these acids were found at low levels in neutral lipids and phospholipids. Their subsequent metabolic pathway and their possible interaction with the biochemical mechanisms involving phospholipids are under investigation.

Adipose Tissue↗
PubMedDate not supplied

[Biodegradation of petroleum hydrocarbons in soil inoculated with yeasts].

Yeast species belonging to the Candida genus were added to the greyish-brown soil of the Apsheron Peninsula under laboratory conditions. The rate of CO2 production was used to estimate the degradation of crude oil, paraffin, cycloparaffin and aromatic hydrocarbons as well as their oxidized products. The rate of hydrocarbon degradation in the soil inoculated with yeast cells was shown to drop down gradually. The effective action on the process of hydrocarbon degradation depended on the special properties of an inoculated population and on the structure of a hydrocarbon. Some yeast species stimulated the degradation of various aromatic hydrocarbons and their oxidized products. Aromatic hydrocarbons were decomposed at a lower rate comparing to their oxidized products. When the soil was inoculated with C. guilliermondii populations, n-hexadecane added to the soil at a concentration of 1% was decomposed within 250-300 days. Field experiments confirmed that crude oil biodegradation was more intensive in the soil inoculated with yeast cells.

Azerbaijan↗
PubMed1979

The respiratory effects of dezocine and pentazocine in man.

The respiratory effects of dezocine and pentazocine were studied in five volunteers. Based on their effects over a 3-hour period, it was found that dezocine was 8.6 times as potent as pentazocine in terms of their respiratory depressant effects. The clinical significance of these findings remains to be determined.

Analgesics↗