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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Trees 6 (1992), S. 32-36 
    ISSN: 1432-2285
    Keywords: Abies ; Cuticle ; Monoterpene ; Octanol/water partition coefficient ; Picea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Cuticle/water partition coefficients (Kc/w) for d-limonene, α-pinene and β-pinene were determined by an extrapolation and a desorption method. The sorption experiments were carried out with isolated angiosperm and gymnosperm cuticles and with [14C]-labelled monoterpenes, which were obtained biosynthetically. Both methods were suitable for the determination of the Kc/w of volatile hydrophobic compounds. For the angiosperm cuticles the partition coefficients are of the order of 104, which indicates a high accumulation of monoterpenes in the cuticle. The values of the conifer cuticles of Picea abies (L.) Karst. and Abies alba Mill., however, are lower due to their high lignin content. This is proved by the increase of the partition coefficients after removal of polar and phenolic components. The Kc/w can be estimated with good accuracy from the octanol/water partition coefficient, which was determined experimentally.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Trees 6 (1992), S. 172-177 
    ISSN: 1432-2285
    Keywords: Citrus ; Cuticle ; Diffusion coefficient ; Limonene ; Monoterpene ; Ozone ; Permeability coefficient ; Permeation ; α-Pinene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Permeation parameters of isolated cuticular membranes of Citrus aurantium L. for gaseous monoterpenes were determined by an isostatic system. For α-pinene and d-limonene permeability coefficients range from 4.3 × 10−11 m−2 s−1 to 7.3 × 10−11 m−2 s−1. These values can be compared to that measured for benzene gas at the cuticle of Citrus. The permeability coefficients of the two monoterpenes did not differ significantly, in contrast to their diffusioin coefficients. The diffusion coefficient values are 3.7 × 10−15 m−2 s−1 for limonene and 15.5 × 10−15 m−2 s−1 for α-pinene. The reason for this difference is still unclear. A dependence of the permeation parameters on the direction of the monoterpene transport could not be observed. Moreover, there are some indications that, in spite of its heterogeneous character, the cuticular membrane of Citrus is homogeneous in respect to the transport of small gaseous molecules. An exposure to environmentally relevant ozone concentrations for 6 months did not change the permeation characteristics of the membrane. Due to the high variability of the samples only a tendency towards higher permeability coefficients of cuticles treated with 80 ppb ozone was observed. This may be attributed to a reduced tension of the membrane caused by chain fractions.
    Type of Medium: Electronic Resource
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