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Visar resultat 1 - 5 av 166 avhandlingar som matchar ovanstående sökkriterier.

1. 1. 13C-Enriched Dehydrogenation Polymers Used for Studying Light-Induced Yellowing of Lignocellulosic Materials

   Författare :Jim Parkås; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lignin model compounds; differentiating xylem; yellowing; Picea abies; 13C NMR spectroscopy; lignin; DHP; 13C-enrichment; solid state; spruce;

   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

3. 2. Achieving carbon isotope mass balance in northern forest soils, soil respiration and fungi

   Författare :Björn Boström; Alf Ekblad; Phil Ineson; Örebro universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; 13C; Carbon cycle; Ectomycorrhizal fungi; Forest soil; Microbial respiration; Soil respiration; Stable isotopes; Biology; Biologi; Biology; Biologi;

   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

4. 3. Contrast-Enhanced Magnetic Resonance Angiography - Development and optimization of techniques for paramagnetic and hyperpolarized contrast media

   Författare :Jonas Svensson; Malmö Medicinsk strålningsfysik; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; egenskaper elektriska; Kondenserade materiens egenskaper:elektronstruktur; spectroscopy; relaxation; Angiography; Magnetic resonance; Contrast-enhanced; Hyperpolarized; Condensed matter:electronic structure; 13C; supraconductors; electrical; magnetic and optical properties; magnetiska och optiska ; supraledare; magnetisk resonans; spektroskopi;

   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

5. 4. Hyperpolarized Nuclei for NMR Imaging and Spectroscopy – Methodology and model studies of lung and vascular function

   Författare :Sven Månsson; Malmö Medicinsk strålningsfysik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; lung function; 3He; 13C; 129Xe; Elektroteknik; Electrical engineering; Magnetic resonance; hyperpolarized;

   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

7. 5. Impact of root and mycorrhizal exudation on soil carbon fluxes : influence of elevated CO2 and metals

   Författare :Emma M. Johansson; Patrick van Hees; Bert Allard; Phil Ineson; Örebro universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; amino acids; 13C; carbon cycle; ectomycorrhiza; elevated CO2; exudation; DOC; LMWOA; metal stress; monosaccharides; oxalate; Pinus sylvestris; saprotrophic fungi; soil respiration; NATURAL SCIENCES; NATURVETENSKAP; Environmental chemistry; Miljökemi; Enviromental Science; Miljövetenskap;

   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