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- Member of: ASU Electronic Theses and Dissertations
Description
A new analytical method is proposed for measuring the deuterium to hydrogen ratio (D/H) of non-stoichiometric water in hydrous minerals via pyrolysis facilitated gas-chromatography - isotope ratio mass spectrometry (GC-IRMS). Previously published analytical methods have reported a poorly understood nonlinear dependence of D/H on sample size, for which any accurate correction is difficult. This sample size effect been variously attributed to kinetic isotope fractionation within the mass spectrometer and peripheral instruments, ion source linearity issues, and an unstable H_3^+-factor or incorrect H_3^+-factor calculations. The cause of the sample size effect is here identified by examinations of individual chromatograms as well as bulk data from chromatographic peaks. It is here determined that it is primarily an artifact of the calculations employed by the manufacturer's computer program, used to both monitor the functions of the mass spectrometer and to collect data. Ancillary causes of the sample size effect include a combination of persistent background interferences and chromatographic separation of the isotopologues of molecular hydrogen. Previously published methods are evaluated in light of these findings. A new method of H_3^+-factor and D/H calculation is proposed which makes portions of the Isodat software as well as other published calculation methods unnecessary. Using this new method, D/H is measured in non-stoichiometric water in chert from the Cretaceous Edwards Group, Texas, as well as the Precambrian Kromberg Formation, South Africa, to assess hydrological conditions as well as to estimate the maximum average surface temperature during precipitation of the chert. Data from Cretaceous chert are consistent with previously published data and interpretations, based upon conventional analyses of large samples. Data from Precambrian chert are consistent with maximum average surface temperatures approaching 65°C during the Archean, instead of the much lower temperatures derived from erroneous methods of sample preparation and analysis. D/H is likewise measured in non-stoichiometric water in silicified basalt from the Precambrian Hooggenoeg Complex, South Africa. Data are shown to be consistent with D/H of the Archean ocean similar to present day values.
ContributorsSheehan, Michael Robert (Author) / Knauth, Leroy P (Thesis advisor) / Anbar, Ariel (Committee member) / Farmer, Jack (Committee member) / Arizona State University (Publisher)
Created2011
Description
This work describes the development of a device for measuring CO2 in breath, which has applications in monitoring a variety of health issues, such as Chronic Obstructive Pulmonary Disease (COPD), asthma, and cardiovascular disease. The device takes advantage of colorimetric sensing technology in order to maintain a low cost and high user-friendliness. The sensor consists of a pH dye, reactive element, and base coated on a highly porous Teflon membrane. The transmittance of the sensor is measured in the device via a simple LED/photodiode system, along with the flow rate, ambient relative humidity, and barometric pressure. The flow is measured by a newly developed flow meter described in this work, the Confined Pitot Tube (CPT) flow meter, which provides a high accuracy with reduced flow-resistance with a standard differential pressure transducer. I demonstrate in this work that the system has a high sensitivity, high specificity, fast time-response, high reproducibility, and good stability. The sensor has a simple calibration method which requires no action by the user, and utilizes a sophisticated, yet lightweight, model in order to predict temperature changes on the sensor during breathing and track changes in water content. It is shown to be effective for measuring CO2 waveform parameters on a breath-by-breath basis, such as End-Tidal CO2, Alveolar Plateau Slope, and Beginning Exhalation Slope.
ContributorsBridgeman, Devon (Author) / Forzani, Erica S (Thesis advisor) / Nikkhah, Mehdi (Committee member) / Holloway, Julianne (Committee member) / Raupp, Gregory (Committee member) / Emady, Heather (Committee member) / Arizona State University (Publisher)
Created2017
Description
Interprofessional educators increasingly recognize the importance of establishing graduated interprofessional learning strategies to socialize and prepare learners to work in collaborative care environments. Interprofessional socialization (IPS) is the process of bringing students together from different disciplines to learn from, with, and about each other. However, education programs struggle to systematically integrate evidence-based interprofessional learning. Community-engaged learning, a pedagogical tool adaptable to diverse circumstances, offers an opportunity to expand IPS. The purpose of this mixed methods action research dissertation study was to explore the factors that contribute to IPS through participation in a community-engaged learning course and how IPS evolves among early learners. In this study, I explored several factors, including theoretically-grounded and contextually relevant teaching and learning strategies pivotal to IPS. Specifically, I created and facilitated an innovative pilot Interprofessional Education and Community Health course, guided by experiential learning theory, asset-based and critical pedagogy and flow theory. I found that these theoretically guided instructional techniques nurtured the benefits of team-based experiential learning, inspired a community of confident learners through praxis, and promoted optimal engagement in challenging and meaningful health promotion activities. The learner’s diverse backgrounds, meaningful community-engagement, and challenging collaborative assignments contributed to IPS. The shared novel real-world experiences ignited emotional reactions that nurtured their relationships; facilitating their ability to address conflicts. They sustained motivation to participate in community-engaged learning and maintained a consistent strong belief in the importance of working as a team. Whereas, their understanding of interprofessional teamwork, comfort and preference working on interprofessional teams grew over time. Four pedagogical strategies pivotal to interprofessional socialization emerged for use with community-engaged interprofessional education: 1) purposeful community partnerships, 2) structured collaborative written assignments, 3) intentional conversations, and 4) welcoming cultural assets.
ContributorsRamella, Kelly Johnson (Author) / Sampson, Carrie (Thesis advisor) / Ross, Allison (Committee member) / Yañez-Fox, Lisa (Committee member) / Arizona State University (Publisher)
Created2021