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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- All Subjects: Environmental engineering
Description
This dissertation encompasses the interaction of antimicrobial chemicals and emerging contaminants with multi-drug resistant (MDR) bacteria and their implications in engineered systems. The aim is to investigate the effect of combination antimicrobials on MDR bacteria E. coli, evaluate the extent of synergism and antagonism of utilizing two distinct biocidal chemicals, and evaluate the influence of endocrine-disrupting chemicals (EDCs) on protein production in response to stressors. Resistance mechanisms of bacteria such as E. coli include the use of protein systems that efflux excess nutrients or toxic compounds. These efflux proteins activate in response to environmental stressors such as contaminants and antimicrobials to varying degrees and are major contributors to antibiotic resistance in pathogenic bacteria. As is the case with engineered microbial environments, large quantities of emerging contaminants interact with bacteria, influencing antibiotic resistance and attenuation of these chemicals to an unknown degree. Interactions of antimicrobials on MDR bacteria such as E. coli have been extensively studied for pathogens, including synergistic combinations. Despite these studies in this field, a fundamental understanding of how chemicals influence antibiotic resistance in biological processes typical of engineered microbial environments is still ongoing. The impacts of EDCs on antibiotic resistance in E. coli were investigated by the characterization of synergism for antimicrobial therapies and the extrapolation of these metrics to the cycling of EDCs in engineered systems to observe the extent of antibiotic resistance proteins to the EDCs. The impact of this work provides insight into the delicate biochemistry and ongoing resistance phenomena regarding engineered systems.
ContributorsNovoa, Diego Erick (Author) / Conroy-Ben, Otakuye (Thesis advisor) / Abbazadegan, Morteza (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2022
Description
The measurement of the radiation and convection that the human body experiences are important for ensuring safety in extreme heat conditions. The radiation from the surroundings on the human body is most often measured using globe or cylindrical radiometers. The large errors stemming from differences in internal and exterior temperatures and indirect estimation of convection can be resolved by simultaneously using three cylindrical radiometers (1 cm diameter, 9 cm height) with varying surface properties and internal heating. With three surface balances, the three unknowns (heat transfer coefficient, shortwave, and longwave radiation) can be solved for directly. As compared to integral radiation measurement technique, however, the bottom mounting using a wooden-dowel of the three-cylinder radiometers resulted in underestimated the total absorbed radiation. This first part of this thesis focuses on reducing the size of the three-cylinder radiometers and an alternative mounting that resolves the prior issues. In particular, the heat transfer coefficient in laminar wind tunnel with wind speed of 0.25 to 5 m/s is measured for six polished, heated cylinders with diameter of 1 cm and height of 1.5 to 9 cm mounted using a wooden dowel. For cylinders with height of 6 cm and above, the heat transfer coefficients are independent of the height and agree with the Hilpert correlation for infinitely long cylinder. Subsequently, a side-mounting for heated 6 cm tall cylinder with top and bottom metallic caps is developed and tested within the wind tunnel. The heat transfer coefficient is shown to be independent of the flow-side mounting and in agreement with the Hilpert correlation.
The second part of this thesis explores feasibility of employing the three-cylinder concept to measuring all air-flow parameters relevant to human convection including mean wind speed, turbulence intensity and length scale. Heated cylinders with same surface properties but varying diameters are fabricated. Uniformity of their exterior temperature, which is fundamental to the three-cylinder anemometer concept, is tested during operation using infrared camera. To provide a lab-based method to measure convection from the cylinders in turbulent flow, several designs of turbulence-generating fractal grids are laser-cut and introduced into the wind tunnel.
ContributorsGupta, Mahima (Author) / Rykaczewski, Konrad (Thesis advisor) / Pathikonda, Gokul (Thesis advisor) / Middel, Ariane (Committee member) / Arizona State University (Publisher)
Created2024
Description
The escalating global demand for food production underscores the urgent need for sustainable agricultural innovations. This research contributes new insights into the environmental benefits of using urine-derived phosphorus (P) fertilizers by closing the nutrient loop and applying the technology to agricultural food systems. Anticipatory life cycle assessment was used to quantify the environmental impacts of replacing conventionally mined P fertilizer with recovered urine-derived P fertilizer within the production of beef and plant-based burgers. Results shows that implementing recovered P fertilizer provides greater environmental benefits for all environmental impact categories, with global warming, eutrophication, and water consumption being the main impact categories examined in this study. Urine-derived P fertilizer use in beef burger production led to a 4% reduction in global warming impacts (3% for plant-based), 15% reduction in eutrophication (2% for plant-based), and 42% reduction in water consumption (46% for plant-based). Uncertainty in the results was accounted for using Monte Carlo simulation with 10,000 runs to rank the four burger production scenarios (e.g., conventional and urine-derived beef burger and conventional and urine-derived plant-based burger) based on their environmental impact on global warming, eutrophication, and water use under conditions of baseline, realistic, and maximum uncertainty. Under conditions of realistic uncertainty, implementing urine-derived P fertilizer for beef burger production was considered beneficial for global warming, eutrophication, and water consumption, with 78%, 99%, and 89% of the runs showing environmental benefits, respectively. Due to the lower P fertilizer requirements in plant-based burger production, uncertainty assessment under realistic conditions showed that a reduction in water use was the only expected benefit of implementing recovered P fertilizer, with 71% of the runs providing water use benefits. These results show that closing the nutrient loop by implementing urine-derived P fertilizers can be beneficial when applied to the correct agricultural food system (e.g., beef burger production) and is expected to have the most pronounced benefits with regard to water savings.
ContributorsEvans, Dilan (Author) / Boyer, Treavor (Thesis advisor) / Ravikumar, Dwarak (Thesis advisor) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2024
Structural Investigation of Quaternary Ammonium-Functionalized Networks for Gas Capture Applications
Description
As society moves to reduce the effects of climate change, there is a growing needfor the use of polymer science in technologies to mitigate the emission of carbon
dioxide. Networks containing quaternary ammonium groups with corresponding
HCO3 ions providing the mobile counter-charge in the networks have been reported
to capture carbon dioxide directly from the atmosphere through a moisture swing
mechanism, among other mechanisms. In this work, microstructural analysis of
synthesized polystyrene-based anion exchange networks is conducted using known
characterization techniques to better understand if variations in sorbent microstructure
adjust the distances between the quaternary ammonium groups. Additional surface
morphology studies of these sorbents are conducted. X-Ray Diffraction (XRD) spectra
reveal the amorphous structure of these polymers and the ability to adjust the distance
between quaternary ammonium groups by introducing different spacer groups and
various anions into the networks, which may affect the spontaneity of the CO2
to chemisorb to these sorbents. However, Wide Angle X-Ray Scattering (WAXS)
conflicts with the XRD data, indicating a change in distance between these groups is
not achieved. Additionally, WAXS data indicates an ability to increase the homogeneity
of structure in these materials by introducing larger counterions into the networks.
Small Angle X-Ray Scattering (SAXS) reveals no obvious large morphological features
in these sorbents, which is supported by Scanning Electron Microscopy (SEM) images.
In conclusion, XRD and WAXS experiments exhibit conflicting data regarding the
ability to adjust the distances between the quaternary ammonium groups in these
networks. Proposed actions to resolve this conflict are presented. Finally, SEM sheds
light on particle size and morphological features of these materials.
ContributorsBenard, Emmie Marie (Author) / Green, Matthew (Thesis advisor) / Jin, Kailong (Committee member) / Yang, Sui (Committee member) / Arizona State University (Publisher)
Created2024
Description
Waterborne opportunistic pathogens, particularly non-tuberculous mycobacteria(NTM), pose significant challenges to public health. This study aims to address critical gaps in understanding mycobacterial succession within premise plumbing systems, focusing on diversity, morphology, and factors influencing persistence. A premise plumbing pipe rack experiment was conducted with various pipe materials under real-world conditions. Water samples were collected and analyzed for NTM presence using culture-based and molecular techniques. During the cultivation of various isolates, two main morphologies were noted, revealing insights into the dynamics of mycobacterial communities within premise plumbing systems. Polymerase chain reaction (PCR) analysis attributed the yellow colonies to M. intracellulare or M. chimaera, while the white colonies represented unidentified mycobacterial species. The temporal dynamics of mycobacterial presence, assessed through PCR analysis over 7 weeks, demonstrated fluctuations influenced by source water conditions and disinfectant levels. Different pipe materials exhibited varying levels of mycobacterial colonization, with PVC pipes showing the highest percent positive. Species-level PCR analysis revealed dominance of M. intracellulare/M. chimaera in copper and PEX pipes, while "other" species were more prevalent in PVC pipes. The dominance of human-relevant species raises concerns for health, particularly among immunocompromised individuals. Future sequencing work is necessary to distinguish between M. intracellulare and M. chimaera, a differentiation that could provide valuable insights into the sources and transmission routes of these pathogens in the environment.
ContributorsCahill, Molly (Author) / Hamilton, Kerry A (Thesis advisor) / Boyer, Treavor (Committee member) / Voth-Gaeddert, Lee (Committee member) / Arizona State University (Publisher)
Created2024
Description
In order to optimize the ability of Geobacter sulfurreducens to produce electrical current and remediate wastewater, several physiological challenges must be overcome. The accumulation of protons at the electrode surface of a microbial fuel cell (MFC) decreases the pH, and, thus, the ability of the bacteria to maintain baseline metabolic conditions. To evaluate the extent to which this pH change hinders performance, the buffer concentration supplied to G. sulfurreducens reactors was varied. The resulting biofilms were subjected to chronoamperometry, cyclic voltammetry, and confocal microscopy to determine metabolic function and biofilm thickness. Biofilms grown with a 30-mM bicarbonate buffer experienced limitations on cell function and current output due to proton accumulation, while 90- and 150-mM conditions alleviated these limitations most of the measurements. Based on the current output, estimated biofilm thickness, and the medium-rate and slow-rate scan rate cyclic voltammetry, benefits exist for buffer concentrations greater than 30 mM. If the kinetics of G. sulfurreducens electron transfer are optimized, the potential of the technique to be implemented for energy recovery is improved.
ContributorsCoulam, Jordan (Author) / Torres, Cesar (Thesis advisor) / Delgado, Anca (Committee member) / Rittmann, Bruce (Committee member) / Arizona State University (Publisher)
Created2024
Description
Nitrate leaching from agricultural systems poses a threat to ecosystems and human health. Integrating 2D carbon-based graphite nano additive (GNA) soil amendments previously demonstrated potential in mitigating nitrate loss, yet the responsible mechanism was unclear. To clarify the causal mechanism, this dissertation aimed to identify and understand mechanisms of how addition of graphite nano-additive (GNA) soil amendment reduces N leaching through agricultural soil by sequential investigation employing laboratory soil incubation tests, batch adsorption experiments, soil column experiments, and greenhouse pot study. Soil incubation tests were conducted with four commercially available graphene nanomaterials to establish that soil microbial activity indicated by respiration was significantly enhanced when soil was amended with graphene (e.g., GNA). Additionally, gene abundance assessment from the same incubation tests indicated a potentially slowed soil nitrification (ammonium to nitrate conversion) by GNA. Separate batch absorption tests indicated that GNA was unlikely to retain nitrate through adsorption. Soil column experiments were designed to probe the dependency of N retention in GNA-amended soil primarily due to altered microbial activity from assessing the impact of temperature, soil saturation, sterility, hydraulic retention time, GNA dose, and soil organic carbon. Finally, a greenhouse plant growth study was designed to assess how GNA impacts soil biology. Enzyme activity indicated GNA could stimulate soil carbon mineralization and improve soil bioavailable carbon. Gene abundance assessment showed total bacterial community size was unimpacted but selected and suppressed certain bacterial groups (e.g., suppressed bacterial amoA gene abundance).16S bacterial community sequencing showed that GNA significantly altered the bulk and rhizosphere soil microbiome composition. GNA-induced selection of certain bacterial classes (e.g., Bacilli) holds significant implications in aspects of plant growth and nutrient acquisition. This dissertation revealed mechanisms behind GNA-induced decrease of nitrate leaching in agricultural soil, aiding progress to its integration into conventional agriculture to improve nitrogen fertilizer efficiency for a food-secure future.
ContributorsDas, Partho (Author) / Westerhoff, Paul (Thesis advisor) / Penton, Christopher Ryan (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2024