Sökning: "13C-enrichment"

Visar resultat 1 - 5 av 6 avhandlingar innehållade ordet 13C-enrichment.

  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. Light-induced yellowing studied with ¹³C-enriched CW-DHP and solid state ¹³C NMR spectroscopy

    Författare :Jim Parkås; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; solid state; yellowing; picea abies; differentiation xylem; spruce; DHP; lignin; 13C NMR spectroscopy; 13C-enrichment;

    Sammanfattning : .... LÄS MER

  4. 3. 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

  5. 4. Geochemical and sedimentary signatures of Phanerozoic events

    Författare :Jane Wigforss-Lange; Berggrundsgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; geokemi; Sedimentology; Petrology; mineralogy; geochemistry; Petrologi; mineralogi; Carbon and oxygen isotopes; Jurassic-Cretaceous boundary; K-T boundary; Late Silurian; Events; Trace elements; Sedimentologi;

    Sammanfattning : Geological and biological catastrophic events have occurred repeatedly in the Earth's history, leaving traces in the global stratigraphical record in the form of sedimentary features, geochemical anomalies and biotic turnovers. This thesis focuses on the sedimentological and geochemical signatures of several key events in the Phanerozoic stratigraphical record, and aims to interpret the different signals and the causal mechanisms behind each of these events. LÄS MER

  7. 5. Surfactant metabolism in the newborn : the impact of ventilation strategy and lung disease

    Författare :Kajsa Bohlin; Karolinska Institutet; Karolinska Institutet; []
    Nyckelord :Surface active agents; pulmonary surfactant; respiratory distress syndrome; stable isotope; artificial respiration; continuous positive airway pressure; metabolism; rabbit; compliance; preterm; newborn;

    Sammanfattning : Developmental deficiency in pulmonary surfactant leads to respiratory distress syndrome (RDS) in preterm infants, but all newborns may have impaired surfactant metabolism secondary to lung disease or ventilator induced lung injury. Exogenous surfactant treatment is usually administered in conjunction with mechanical ventilation. LÄS MER