Sökning: "13C"
Visar resultat 1 - 5 av 166 avhandlingar innehållade ordet 13C.
1. 13C-Enriched Dehydrogenation Polymers Used for Studying Light-Induced Yellowing of Lignocellulosic Materials
Sammanfattning : This study deals with the use of selectively 13C-enriched dehydrogenation polymers (DHPs) as models of lignin in lignocellulosic materials for elucidating the reaction pathways involved in light-induced yellowing. Methods for the synthesis of coniferin, a precursor to lignin and DHP, selectively 13C-enriched in the aromatic ring (positions 1, 3, 4, and 5) have been developed. LÄS MER
2. Achieving carbon isotope mass balance in northern forest soils, soil respiration and fungi
Sammanfattning : Northern forests contain a large part of the global terrestrial carbon pool and it is unclear whether they will be sinks or sources for atmospheric carbon if the climate warms as predicted. Stable isotope techniques provide unique tools to study the carbon cycle at different scales but the interpretation of the isotope data is impaired by our inability to close the carbon isotope mass balance of ecosystems. LÄS MER
3. Contrast-Enhanced Magnetic Resonance Angiography - Development and optimization of techniques for paramagnetic and hyperpolarized contrast media
Sammanfattning : Contrast-enhanced magnetic resonance angiography (CE-MRA) is a diagnostic method for imaging of vascular structures based on nuclear magnetic resonance. Vascular enhancement is achieved by injection of a contrast medium (CM). LÄS MER
4. Hyperpolarized Nuclei for NMR Imaging and Spectroscopy – Methodology and model studies of lung and vascular function
Sammanfattning : Based on the principle of nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are widely used methods in medical diagnostic imaging and biological research. Clinical MRI has been restricted to imaging of protons, for reasons of sensitivity. LÄS MER
5. Impact of root and mycorrhizal exudation on soil carbon fluxes : influence of elevated CO2 and metals
Sammanfattning : The thesis concerns the behavior of root and ectomycorrhizal (ECM) exudates. In particular, the dynamics of soluble low molecular weight (LMW) organic compounds such as organic acids (LMWOAs), amino acids, monosaccharides, and dissolved organic carbon (DOC) have been studied. LÄS MER