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  • Articles: DFG German National Licenses  (2)
  • 2005-2009
  • 1995-1999  (2)
  • 1945-1949
  • Alkaloids  (1)
  • Commercial steel  (1)
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  • Articles: DFG German National Licenses  (2)
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  • 1
    ISSN: 1433-075X
    Keywords: Key words Surface transformation ; Commercial steel ; Multiple pulsed laser radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  A key innovation in materials processing of pre-formed metal parts is reported herein. The ”QQC Process” involves the judicious selection of exposure parameters to three pulsed lasers (excimer, Nd-YAG and CO2) simultaneously for treatment of the work piece. Pre-formed commercial steel parts are hardened and/or toughened, and/or clad with TiC improving performance by at least one order of magnitude. Two examples are detailed: a punch for aluminum can production and a fuel injector nozzle. In the latter case it has been shown that some tens of microns of the metal are transformed to a noncrystalline phase, in the middle of the workpiece.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1561
    Keywords: Alkaloids ; mass spectrometry ; infrared spectroscopy ; amphibians ; ants ; decahydroquinolines ; quinolizidines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three alkaloids—two minor decahydroquinolines (DHQs) and a major quinolizidine—were detected in an extract of a Brazilian myrmicine ant (Solenopsis (Diplorhoptrum) sp. picea group). One DHQ (3) was identical to a known frog-skin alkaloid, cis-195A (cis-5-methyl-2-propyldecahydroquinoline), while the second DHQ, an isomer of 3, designated 195J, was assigned a tentative cis-2-methyl-5-propyldecahydroquinoline structure (2) based on mass and infrared spectra. The third alkaloid proved identical to the frog-skin alkaloid 195C, for which a structure had not been previously proposed. Mass and infrared spectral analysis, including chemical ionization tandem mass spectrometry, indicated a 4-methyl-6-propylquinolizidine structure (1) for 195C. The four possible diastereomers were synthesized and the (6Z,10E)-4-methyl-6-propylquinolizidine diastereomer (1b) was identical to the natural alkaloid. Skin extracts of a population of a Madagascan mantelline frog contained, among other alkaloids, minor amounts of the same alkaloid triad 1–3 with 1 again predominating. The common occurrence of alkaloids 1–3 in both ant and frog supports the hypothesis that ants are a likely dietary source for sequestered frog-skin alkaloids and brings to six, the alkaloid classes common to ant and frog.
    Type of Medium: Electronic Resource
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