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  • Articles  (2)
  • 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry  (1)
  • 1H NMR  (1)
  • 2010-2014  (1)
  • 2005-2009
  • 1990-1994  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 628-634 
    ISSN: 0749-1581
    Keywords: 13C NMR ; 1H NMR ; 4,9-Dihetero-(Z,Z)-cyclodeca-1,6-dienes ; Ring inversion barriers ; Restricted rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dynamic 1H and 13C NMR spectra of a series of mono- and bis-annelated 4,9-dihetero-(Z,Z)-cyclodeca-1,6-dienes were obtained and are discussed with respect to ground-state conformers and the barriers to ring inversion, and to the restricted rotation about exocyclic partial C,N double bonds. The ten-membered rings are, with one exception, anancomeric chair conformers and interconvert via a combination of single bond rotations and bond angle bendings. Depending on the heteroatoms present, the series of decreasing barriers to ring inversion S 〉 NH 〉 O was obtained. Benzannelation decreases the free energy of activation of the same dynamic process owing to greater intramolecular transannular H,H interactions.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2021-01-11
    Description: Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000–2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO2, CO, CH4 and N2O balances of Europe following a dual constraint approach in which (1) a landbased balance derived mainly from ecosystem carbon inventories and (2) a land-based balance derived from flux measurements are compared to (3) the atmospheric data-based balance derived from inversions constrained by measurements of atmospheric GHG (greenhouse gas) concentrations. Good agreement between the GHG balances based on fluxes (1294±545 Tg C in CO2-eq yr−1), inventories (1299±200 Tg C in CO2-eq yr−1) and inversions (1210±405 Tg C in CO2-eq yr−1) increases our confidence that the processes underlying the European GHG budget are well understood and reasonably sampled. However, the uncertainty remains large and largely lacks formal estimates. Given that European net land to atmosphere exchanges are determined by a few dominant fluxes, the uncertainty of these key components needs to be formally estimated before efforts could be made to reduce the overall uncertainty. The net land-to-atmosphere flux is a net source for CO2, CO, CH4 and N2O, because the anthropogenic emissions by far exceed the biogenic sink strength. The dual-constraint approach confirmed that the European biogenic sink removes as much as 205±72 Tg C yr−1 from fossil fuel burning from the atmosphere. However, This C is being sequestered in both terrestrial and inland aquatic ecosystems. If the C-cost for ecosystem management is taken into account, the net uptake of ecosystems is estimated to decrease by 45% but still indicates substantial C-sequestration. However, when the balance is extended from CO2 towards the main GHGs, C-uptake by terrestrial and aquatic ecosystems is offset by emissions of non-CO2 GHGs. As such, the European ecosystems are unlikely to contribute to mitigating the effects of climate change.
    Description: Published
    Description: 3357–3380
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: carbon dioxide ; methane ; soil ; ecosystems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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