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  • 1990-1994  (2)
  • Analytical Chemistry and Spectroscopy  (1)
  • Ozone uptake  (1)
  • 1
    ISSN: 1432-2285
    Keywords: Ozone uptake ; Stomatal conductance ; Spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The uptake of air pollutants depends both on pollutant concentration and on stomatal conductance. This paper deals with the uptake of ozone (O3) from the air into the needles of Norway spruce [Picea abies (L.) Karst.] under ambient climatic conditions. Regulation of O3 uptake by the stomata is shown and also the difference between the “physiologically active O3 concentration” and the O3 concentration of the ambient air. Data from the sun and shade crown of spruce trees at 1000 m a.s.l. are presented. Analysis of data from three vegetation periods has shown that at low ambient O3 concentrations the O3 uptake is largely regulated by stomatal conductance. Water vapour pressure deficit (VPD) of the atmosphere is the climatic factor which showed the highest positive correlation with O3 concentration. However, a high leaf-air VDP led to stomatal closure, thus reducing the O3 uptake in the needles despite high O3 concentrations in the ambient air. The potential O3 stress caused by high O3 concentrations can be strongly mitigated by this natural closing of the stomata and the simultaneous occurrence of moderate drought stress.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 352-356 
    ISSN: 0749-1581
    Keywords: Separated-local-field NMR ; Chemical-shift tensor orientations ; Poly(ethylene oxide) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C chemical-shift tensor orientations in the OCH2CH2O moieties of poly(ethylene oxide) (PEO) and poly(ethylene terephthalate) (PET) were determined by means of 1H—13C separated-local-field NMR spectroscopy, and the literature values for the shift tensors in polyethylene (PE) and polyoxymethylene (POM) were improved. An angular resolution of ± 4° was attained on standard equipment with 90° pulse lengths exceeding 4 μs. Relatively high uniformity of the methylene tensor orientations, complying with local molecular symmetry, was found.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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