Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 36 for “"Hydrogen isotope"”.
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Hydrogen isotope fractionation in ammonia-oxidizing archaea
In recent years, the potential of the hydrogen stable isotope composition (δ2H) signature of isoprenoid glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids of ammonia-oxidizing archaea (class Nitrososphaeria) as a novel palaeohydrological proxy has gained increasing attention. This PhD …
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The oxygen, carbon & hydrogen isotope geochemistry of the Phalaborwa Complex, South Africa
… detailed studies on multi-mineral oxygen and hydrogen isotopes or multi-rock carbonate carbon isotope data for the Phalaborwa Complex. These isotope systems are useful for identifying mineral disequilibrium and alteration, analyzing contamination and constraining the mantle source. Previous …
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Iridium complexes as highly active catalysts for hydrogen isotope exchange and hydrogen borrowing processes
… which were found to be excellent catalysts for hydrogen isotope exchange and olefin hydrogenation processes. The work described within this thesis centres upon the expansion of these catalysts' reactivity in hydrogen isotope exchange, as well as the synthesis and application of a series of novel …
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On the design and further applications of iridium (I) complexes in hydrogen isotope exchange processes
… established. Application of these species in hydrogen isotope exchange (HIE) processes revealed more efficient catalysis and a wider solvent scope when X = BArF. Additionally, these findings have allowed for the development of a novel method for ortho-HIE in unprotected tetrazoles under basic …
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The design and development of hydrogen isotope extraction technologies for a limit-style liquid lithium loop
… plasma-facing component, complete with efficient hydrogen reclamation technologies, there exists a lack in understanding within the community of the thermochemical fundamentals that are envisioned to drive tritium reclamation. Of specific interest are the evolution fluxes of hydrogen isotopes from …
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Superconductivity of thorium hydrides and thorium deuterides
… possibility that a metallic hydride with a high hydrogen to metal atom ratio would be superconducting» we have tested the superconductivity of thorium hydrides and found that Th4 H15 is a superconductor with a transition temperature near 8K, Measurements of the diamagnetic susceptibility of 24 …
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The geochemistry of methane isotopologues
… A strong correlation between clumped- and hydrogen-isotope signatures in microbial methane is identified and quantitatively linked to the availability of H2 and the reversibility of microbially-mediated methanogenesis in the environment. Determination of 13CH3D in combination with …
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The geochemistry of methane isotopologues
… A strong correlation between clumped- and hydrogen-isotope signatures in microbial methane is identified and quantitatively linked to the availability of H₂ and the reversibility of microbially-mediated methanogenesis in the environment. Determination of ¹³CH₃D in combination with …
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Investigating host use and migration by the corn earworm (Noctuidae: Helicoverpa zea) using stable isotope and morphometric techniques.
… resistance evolution We applied a stable carbon isotope technique to test the hypothesis that H. zea migrates North in early summer, feeds on corn, then migrates back South to feed on cotton. We analyzed the relative abundance of the naturally occurring isotope, 13C, incorporated in wing cuticle …
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Effets de la perméabilité du paysage et de la condition physique des individus sur le mouvement de parulines couronnées (seiurus aurocapilla) suivant une translocation expérimentale
… j'ai utilisé la méthode d'eau deutérée («hydrogen isotope-labeled water (D20)»). Cette technique consiste à injecter une quantité connue d'eau deutérée qui sera ensuite diluée par l'eau contenue dans l'oiseau, ce qui permet d'estimer l'eau corporelle totale, qui est elle-même étroitement …
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Topographic reconstructions of the Variscan Belt of Western Europe through the study of fossil hydrothermal systems
This thesis presents the first stable isotope quantification of paleoaltimetry for the Variscan Belt of Western Europe that integrates late-Carboniferous hydrogen isotope ratios of meteoric water in the internal zones in the Armorican Massif (AM) and the French Massif Central (FMC) with …
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Low energy photon mimic of the tritium beta decay energy spectrum
Tritium is a radioactive hydrogen isotope that is typically produced via neutron interaction with heavy water (D2O), producing tritiated water (DTO). As a result of this, tritium accounts for roughly a third of all occupational exposures at a CANDU type nuclear power plant. This identifies a need …
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ISOTOPIC CONSTRAINTS ON ATMOSPHERIC MOISTURE TRANSPORT PROCESSES IN SOUTH AMERICA
… in the past decade have improved measurements of isotopes in water vapor. In this study, I focus on satellite (chapters 2 and 3) and ground-based (chapters 2 and 4) measurements of isotopes in atmospheric water vapor to evaluate processes responsible for moisture transport in tropical and …
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Determination of sediment provenance at drift sites using hydrogen isotopes in lipids
… from the deposition site. We hypothesize that hydrogen isotope ratios of alkenones, a class of lipids from phytoplankton, may provide insight into the source of fine fraction sediment. Because of their restricted sources, broad geographic distribution, and excellent preservation properties, …
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Determination of sediment provenance at drift sites using hydrogen isotopes in lipids
… from the deposition site. We hypothesize that hydrogen isotope ratios of alkenones, a class of lipids from phytoplankton, may provide insight into the source of fine fraction sediment. Because of their restricted sources, broad geographic distribution, and excellent preservation properties, …
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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems
… Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding …
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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems
… Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding …
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Some reactions of methylsilane catalysed by metals
… of methylsilane at 273 K, and the catalysed hydrogen isotope exchange in methylsilane in the range 195 - 300 K have been studied using evaporated metal films of molybdenum, tungsten, rhodium, nickel, and gold.Chemisorption is strong, and is accompanied by dissociation of hydrogen bonded to …
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Aquatic macrophyte-derived biomarkers as palaeolimnological proxies on the Tibetan Plateau
… as potential recorders of lake water δD. Hydrogen isotope analysis of biomarkers is a rapidly evolving field to reconstruct past hydrological conditions and therefore of special relevance on the Tibetan Plateau due to the direct linkage between variations of monsoon intensity and changes …
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Isotope Systematics of Gypsum and its Hydration Water
Triple oxygen and hydrogen isotope analysis of the structurally-bound water in gypsum can provide a direct measure of past hydrologic variability. This thesis presents the development of the water extraction and isotopic measurement procedures, the calculation of the gypsum-water isotope …
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