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Local Environmental Controls On Sulfur Isotope Ratios In Marine Sedimentary Iron Sulfide Minerals, Roger Nicholas Bryant
Local Environmental Controls On Sulfur Isotope Ratios In Marine Sedimentary Iron Sulfide Minerals, Roger Nicholas Bryant
Arts & Sciences Electronic Theses and Dissertations
The controls on the bulk sulfur isotopic composition of marine sedimentary iron sulfides (often referred to simply as pyrite; δ34Spyr) are poorly understood. Nevertheless, many have employed δ34Spyr in efforts to reconstruct the past operation of the biogeochemical sulfur cycle, from the planetary scale down to individual microbial metabolisms. This practice has been thrown into doubt by a growing body of evidence that suggests δ34Spyr is strongly controlled by local environmental conditions. This dissertation describes efforts to determine the mechanisms responsible for the link between local environmental conditions and δ34Spyr. In order to do this, we developed novel laboratory procedures …
Novel Sensing Mechanisms For Chemical And Bio-Sensing Using Whispering Gallery Mode Microresonators, He Huang
Novel Sensing Mechanisms For Chemical And Bio-Sensing Using Whispering Gallery Mode Microresonators, He Huang
McKelvey School of Engineering Theses & Dissertations
Due to their ultra-high quality factor and small mode volume, whispering gallery mode (WGM) microresonators have proven to have exceptional sensing capabilities, with single particle level sensitivity to virions, proteins, and nucleic acids. Current sensing mechanisms rely on measuring the changes in the transmission spectrum of the resonator upon adsorption of the analyte on the surface of the resonator, appearing as either shift, splitting, or broadening of the resonance mode, all of which measure the polarizability of adsorbed analytes. In this dissertation, we present two new sensing mechanisms for WGM microresonators: the measurement of a dynamic chemical reaction around the …
Survey Of ‘Low-Z’ Particles From The Interplanetary Dust Collection In Search Of Idps, Harison Wiesman
Survey Of ‘Low-Z’ Particles From The Interplanetary Dust Collection In Search Of Idps, Harison Wiesman
Undergraduate Theses—Unrestricted
Micrometeorites are one of the most common types of extraterrestrial material that fall to the Earth, beside meteorites and interplanetary dust particles (IDPs). All of these materials are known to contain presolar grains that, when studied in the laboratory, provide information about the origin of the solar system and help to constrain models of nucleosynthesis in stars. Recent studies of micrometeorites revealed the presence of a group of particles with very high C contents. These ultra-carbonaceous Antarctic micrometeorites (UCAMMs) are fine-grained, fluffy particles dominated by highly disordered carbonaceous matter. The presence of H and N isotopic anomalies, abundant presolar grains, …