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 39 for “"Atmospheric Oxygen"”.
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Observation and modeling of atmospheric oxygen millimeter-wave transmittance
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1998.
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Archean continental crust formation and the rise of atmospheric oxygen
… continental crust and the progressive rise of an oxygenated atmosphere. The volume of continental crust on the earliest Earth is a critical parameter for constraining the chemical evolution of major terrestrial reservoirs, and radiogenic isotope signatures document this varying geochemical …
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Analysis of Atmospheric Effects Due to Atmospheric Oxygen on a Wideband Digital Signal in the 60 Ghz Band
… the 60 GHz band. This band is plagued with high atmospheric absorption due to atmospheric oxygen, but has a lot of bandwidth, which makes it desirable for multi-media applications. Recently, research of wideband digital links within the 60 GHz band gained the interest of the wireless …
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Exploring the contributions of liquid-phase sulfur chemistry to the mass-independent sulfur fractionation of the Archean rock record
… one of the strongest indicators for the rise of atmospheric oxygen in the Early Proterozoic. A decade after its discovery, the wide-ranging implications of Archean sulfur MIF have been discussed extensively and despite a number of recent studies on the gas-phase chemistry of sulfur, no definite …
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Reactions of aluminum with halogen containing oxides
… properties. This study examines the effect of atmospheric oxygen concentration (4 or 93% oxygen) on energy propagation of nanometric aluminum with copper oxide (Al+CuO), iron oxide (Al+Fe2O3), calcium iodate (Al+Ca(IO3)2), and iodine pentoxide (I2O5). In all cases energy propagation was …
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Oxygen Transport in Vapor-Deposited Tin-Doped Indium Oxide Films (Diffusion, Electrochemical)
… yttria-stabilized zirconia solid electrolytes. Oxygen transport through the films was monitored between 1100 and 1300(DEGREES)K near atmospheric oxygen pressures using electrochemical techniques. An attempt was made to correlate the transport data to a diffusion model based on the defect …
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Selective Oxidations by Metalloporphyrins and Metallocorroles
… in numerous enzymes such as cytochrome P450 monooxygenases as well as in many useful metal-catalyzed oxidations. Many transition metal catalysts are designed for biomimetic studies of the predominant oxidation catalysts in Nature, the cytochrome P450 enzymes. In this work, a series of …
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Triple oxygen isotope measurements in chert: insights into the Snowball Earth glaciations
… planet, particularly for the trajectory of life, atmospheric oxygen, and planetary habitability. There remains a myriad of questions about the dynamics of these global glaciations, especially regarding the relationship between the cryosphere and hydrosphere during this time. This study analyzes …
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A kinetic and mechanistic study on the oxidation of chromium oxide in pure chemicals and in ferrometallurgical slags
… ambient temperature when in contact with CaO and atmospheric oxygen (Kilau and Shah, 1984; Hattori et al., 1978). Furthermore, the oxidation of Cr[2]O[3] in the presence of Ca(OH)[2] has also been observed at ambient temperature (Petersen, 1998).
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All inorganic colloidal quantum dot LEDs
… materials are subject to degradation due to atmospheric oxygen and water vapor. In contrast, metal-oxide films used in this work are chemically and morphologically stable in air and can withstand numerous organic solvents, which increases the flexibility of device processing. Furthermore, …
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Does Sulfide Affect Short Term Iron Oxidation?
… in this process appears to be reactive oxygen species (ROS) generated by the concurrent partial reduction of dioxygen, although some reduced S species are known to react with Fe(III) directly. These overlapping potentials couple with the recurring oxidation and biogenic reduction of Fe …
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Development of a rapid laboratory predictive test method using fluidised bed techniques for the determination of oxidisability of residual CR (III) present in slags
… hexavalent species in the presence of atmospheric oxygen, at ambient temperaturesalbeit at very slow rates. The produced Cr(VI) is potentially able to leach intounderground waterways and terrestrial water bodies, thus posing an environmentalhazard. In a landfill scenario, the oxidation …
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The Direct Dissociation of Methanol on V(100) Surfaces
… oxidation of the vanadium surface from atmospheric oxygen, water and carbon dioxide. The direct dissociation and partial oxidation of methane on a vanadium surface was studied experimentally with preliminary experimentation being conducted involving the direct dissociation of methanol on …
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Physiological Oxygen and Media Conditions Influence Breast Cancer Hallmarks in Vitro
… standard cell culture incubators maintain near-atmospheric oxygen levels (~18% O2), far exceeding the physiological oxygen levels (2–9% O2) typical of most tissues. Despite their significance, these factors are often studied independently. The main objective of this thesis was to investigate the …
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Murine embryonic stem cells and hypoxia : growth kinetics, metabolism, and plating efficiency
… Growing stem cells in an environment with higher oxygen levels (i.e. the atmospheric oxygen levels that are normally used to cultivate stem cells) could be bad for the cells, as oxygen is toxic due to its powerful oxidative capacity. In this experiment, J1 murine embryonic stem cells were grown at …
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Capsid catalysis : de novo enzymes on viral proteins
… derivative, di-tert-butylcatechol, using atmospheric oxygen as a terminal oxidant. This clone could be purified from control phage via Cu-NTA columns, enabling future library selections for phage that coördinate Cu²+ ions. The M13 semisynthetic enzyme platform complements biocatalysts with …
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Investigating Palaeoatmospheric Composition-Climate Interactions
… model to a rigorous treatment of the relevant atmospheric chemistry and microphysical aerosol processes. This permits the climate response to a particular stratospheric injection of reactive volatile gases to be quantified and for the first time to date applied to a historical volcanic …
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The Degradation and Stabilisation of Epoxide Resins to Ultraviolet Radiation
… material from crosslinking reactions involving atmospheric oxygen. Volatile compounds were evolved during irradiation and their rate of concentration change confirmed the surface layer theory, as did measurement of the torsion modulus of the cured systems. Complete stabilisation of the materials …
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Mass-independent sulfur isotope fractionation during photochemistry of sulfur dioxide
… and provide the most robust constraints on early atmospheric oxygen levels. Smaller mass-independent sulfur isotope anomalies are observed in ice cores and interpreted as a tracer of stratospheric volcanic loading. Photochemistry of sulfur dioxide (SO2) has been implicated as a possible source of …
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Oxygen, the invisible orchestrator of metabolism and disease : a focus on mitochondrial And peroxisomal dysfunction
Variations in atmospheric oxygen levels can be traced over evolutionary time and track closely with the development of multicellular life, speciation events, appearance of placental mammals and the creation of a cardio-respiratory system. As the final electron acceptor for aerobic ATP production, …
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