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  • Articles  (3)
  • Chemistry  (3)
  • 1995-1999  (3)
  • 1970-1974
  • 1965-1969
  • 1995  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 54-58 
    ISSN: 0935-6304
    Keywords: High resolution capillary GC ; High resolution GC-MS ; Zeolite ZSM-5 ; Copaiba tree (Copaifera officinalis) ; Copaiba oil ; Fuel oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oil extracted from the trunk of the copaiba tree (Copaifera officinalis) is composed of sesquiterpenes, C15H24, and a small amount (〉7 %) of sesquiterpenols, C15H26O; these were identified from their Kováts indices and mass spectra. The use of zeolites in the catalytic transformation of this renewable source of hydrocarbons is of interest in the search for new chemicals and ecologically clean fuels. Oil samples from copaiba trees growing in Colombia's Oriental Plains were circulated over zeolite ZSM-5 in a continuous flow fixed-bed micro reactor at 225, 265, and 325°C, for 1 h and subsequently analyzed by HRGC and GC-MS. Whereas only thirty four sesquiterpenes were identified in the original oil, over two hundred compounds were found in the product of the treatment of copaiba oil with zeolite ZSM-5. This complex mixture of sesquiterpenes, light aromatic compounds, and indene and naphthalene derivatives resulted from reactions such as isomerization, hydrogenation, cracking, and dehydrogenation with and without cracking. The amount of cracking products and aromatic compounds increased with reactor temperature but decreased with catalyst aging.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 540-550 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Cerium-rich conversion coatings have been deposited onto aluminium 2024-T351 alloy by immersion into a solution containing 10 g L-1 CeCl3 and 1% H2O2 in a process described as ‘cerating’. Prior to deposition the alloy had been prepared either by using a standard chemical pretreatment used for aerospace alloys before conversion coating or by polishing. X-ray photoelectron spectroscopy and scanning electron microscopy have been used to characterize these cerium-containing conversion coatings. It was found that, during deposition, hydrated cerium oxide initially covered the intermetallics present in the alloy surface and then covered the surface generally. Deposition continued over the intermetallics throughout the conversion coating process, resulting in thick, heavily-cracked regions considerably greater than the average thickness of the film (〉0.3 μm). Elsewhere the coating was generally up to 0.2 μm thick, and appeared to comprised of deposited particles around 100 nm in size.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0173-0835
    Keywords: Two-dimensional polyacrylamide gel electrophoresis ; Human blood platelets ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional (2-D) maps of cytosol and enriched-membrane platelet proteins has allowed the identification of more than 25 spots by three different methods: matching of the platelet gels with other 2-D reference maps, immunoblotting with chemiluminescence detection, and N-terminal sequencing. Different G protein (guanosine triphosphate-binding protein) subunits, cytoskeletal proteins, and proteins common to the human liver, red blood cells and plasma were identified. The two platelet protein maps presented here contribute to the project of identification of human cell and body fluid proteins. They may serve as working tools since platelets are popular models for the study of central nervous system neurotransmitter systems and stimulus-response coupling mechanisms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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