ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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Description
A new challenge on the horizon is to utilize the large amounts of protein found in the atmosphere to identify different organisms from which the protein originated. Included here is work investigating the presence of identifiable patterns of different proteins collected from the air and biological samples for the purposes of remote identification. Protein patterns were generated using high performance liquid chromatography (HPLC). Patterns created could identify high-traffic and low-traffic indoor spaces. Samples were collected from the air using air pumps to draw air through a filter paper trapping particulates, including large amounts of shed protein matter. In complimentary research aerosolized biological samples were collected from various ecosystems throughout Ecuador to explore the relationship between environmental setting and aerosolized protein concentrations. In order to further enhance protein separation and produce more detailed patterns for the identification of individual organisms of interest; a novel separation device was constructed and characterized. The separation device incorporates a longitudinal gradient as well as insulating dielectrophoretic features within a single channel. This design allows for the production of stronger local field gradients along a global gradient allowing particles to enter, initially transported through the channel by electrophoresis and electroosmosis, and to be isolated according to their characteristic physical properties, including charge, polarizability, deformability, surface charge mobility, dielectric features, and local capacitance. Thus, different types of particles are simultaneously separated at different points along the channel distance given small variations of properties. The device has shown the ability to separate analytes over a large dynamic range of size, from 20 nm to 1 μm, roughly the size of proteins to the size of cells. In the study of different sized sulfate capped polystyrene particles were shown to be selectively captured as well as concentrating particles from 103 to 106 times. Qualitative capture and manipulation of β-amyloid fibrils were also shown. The results demonstrate the selective focusing ability of the technique; and it may form the foundation for a versatile tool for separating complex mixtures. Combined this work shows promise for future identification of individual organisms from aerosolized protein as well as for applications in biomedical research.
ContributorsStaton, Sarah J. R (Author) / Hayes, Mark A. (Committee member) / Anbar, Ariel D (Committee member) / Shock, Everett (Committee member) / Williams, Peter (Committee member) / Arizona State University (Publisher)
Created2011
Description
Guided by cognitive, socio-cognitive, and socio-cultural learning theories, large-scale studies over multiple semesters, multiple instructors and at two different institutions have been performed in order to understand the factors that contribute to student performance in general organic chemistry. Students’ cognitive abilities were assessed in a new way based on a categorization of problem types in a standard organic chemistry curriculum. Problem types that required higher cognitive load were found to be more predictive of overall course performance. However, student performance on high cognitive load problems was different when compared in terms of non-cognitive factors, e.g. whether they were pre-health students or not. These results suggested that organic chemistry performance may be significantly influenced by non-cognitive factors. Students’ motivation and related self-regulation factors were then studied using an instrument specifically designed for general organic chemistry, the Organic Chemistry Motivation Survey. Of all the factors examined, self-efficacy was found to be the most significant predictor of performance. Socio-cultural factors were also studied using a newly developed instrument for measuring college students’ cultural and social capital, the Science Capital Questionnaire (SCQ). Of the different socio-cultural variables measured by the SCQ, students’ social connections in college were found to be most predictive of organic chemistry performance. Finally, cognitive and socio-cognitive variables were studied together in the context of gender differences in organic chemistry. Females were found to underperform in comparison to the males. This gap was found to be alarmingly large on the basis of final letter grade, in some semesters the percentage of males earning an A grade was twice as large as that for females. Spatial ability was not a factor that contributed to this difference, nor was the gender of the instructor. Instead, self-efficacy was found to be both significantly different between males and females, and also the factor that connected most strongly to course performance. It is suggested that sociocultural factors be the subject of further study in college science courses.
ContributorsAustin, Ara Cho (Author) / Gould, Ian R. (Thesis advisor) / Atkinson, Robert K. (Committee member) / Williams, Peter (Committee member) / Arizona State University (Publisher)
Created2018
Description
A lack of adequate energy storage technologies is arguably the greatest hindrance to a modern sustainable energy infrastructure. Chemical energy storage, in the form of batteries, is an obvious solution to the problem. Unfortunately, today’s state of the art battery technologies fail to meet the desired metrics for full scale electric grid and/or electric vehicle role out. Considerable effort from scientists and engineers has gone into the pursuit of battery chemistries theoretically capable of far outperforming leading technologies like Li-ion cells. For instance, an anode of the relatively abundant and cheap metal, magnesium, would boost the specific energy by over 4.6 times that of the current Li-ion anode (LiC6).
The work presented here explores the compatibility of magnesium electrolytes in TFSI–-based ionic liquids with a Mg anode (TFSI = bis(trifluoromethylsulfonyl)imide). Correlations are made between the Mg2+ speciation conditions in bulk solutions (as determined via Raman spectroscopy) and the corresponding electrochemical behavior of the electrolytes. It was found that by creating specific chelating conditions, with an appropriate Mg salt, the desired electrochemical behavior could be obtained, i.e. reversible electrodeposition and dissolution. Removal of TFSI– contact ion pairs from the Mg2+ solvation shell was found to be essential for reversible electrodeposition. Ionic liquids with polyethylene glycol chains pendent from a parent pyrrolidinium cation were synthesized and used to create the necessary complexes with Mg2+, from Mg(BH4)2, so that reversible electrodeposition from a purely ionic liquid medium was achieved.
The following document discusses findings from several electrochemical experiments on magnesium electrolytes in ionic liquids. Explanations for the failure of many of these systems to produce reversible Mg electrodeposition are provided. The key characteristics of ionic liquid systems that are capable of achieving reversible Mg electrodeposition are also given.
The work presented here explores the compatibility of magnesium electrolytes in TFSI–-based ionic liquids with a Mg anode (TFSI = bis(trifluoromethylsulfonyl)imide). Correlations are made between the Mg2+ speciation conditions in bulk solutions (as determined via Raman spectroscopy) and the corresponding electrochemical behavior of the electrolytes. It was found that by creating specific chelating conditions, with an appropriate Mg salt, the desired electrochemical behavior could be obtained, i.e. reversible electrodeposition and dissolution. Removal of TFSI– contact ion pairs from the Mg2+ solvation shell was found to be essential for reversible electrodeposition. Ionic liquids with polyethylene glycol chains pendent from a parent pyrrolidinium cation were synthesized and used to create the necessary complexes with Mg2+, from Mg(BH4)2, so that reversible electrodeposition from a purely ionic liquid medium was achieved.
The following document discusses findings from several electrochemical experiments on magnesium electrolytes in ionic liquids. Explanations for the failure of many of these systems to produce reversible Mg electrodeposition are provided. The key characteristics of ionic liquid systems that are capable of achieving reversible Mg electrodeposition are also given.
ContributorsWatkins, Tylan Strike (Author) / Buttry, Daniel A (Thesis advisor) / Wolf, George (Committee member) / Williams, Peter (Committee member) / Arizona State University (Publisher)
Created2016