Matching Items (172)
Description
The objective of this dissertation is to study the optical and radiative properties of inhomogeneous metallic structures. In the ongoing search for new materials with tunable optical characteristics, porous metals and nanowires provides an extensive design space to engineer its optical response based on the morphology-dependent phenomena.This dissertation firstly discusses the use of aluminum nanopillar array on a quartz substrate as spectrally selective optical filter with narrowband transmission for thermophotovoltaic systems. The narrow-band transmission enhancement is attributed to the magnetic polariton resonance between neighboring aluminum nanopillars. Tuning of the resonance wavelengths for selective filters was achieved by changing the nanopillar geometry. It concludes by showing improved efficiency of Gallium-Antimonide thermophotovoltaic system by coupling the designed filter with the cell.
Next, isotropic nanoporous gold films are investigated for applications in energy conversion and three-dimensional laser printing. The fabricated nanoporous gold samples are characterized by scanning electron microscopy, and the spectral hemispherical reflectance is measured with an integrating sphere. The effective isotropic optical constants of nanoporous gold with varying pore volume fraction are modeled using the Bruggeman effective medium theory.
Nanoporous gold are metastable and to understand its temperature dependent optical properties, a lab-scale fiber-based optical spectrometer setup is developed to characterize the in-situ specular reflectance of nanoporous gold thin films at temperatures ranging from 25 to 500 oC. The in-situ and the ex-situ measurements suggest that the
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specular, diffuse, and hemispherical reflectance varies as a function of temperature due to the morphology (ligament diameter) change observed.
The dissertation continues with modeling and measurements of the radiative properties of porous powders. The study shows the enhanced absorption by mixing porous copper to copper powder. This is important from the viewpoint of scalability to get end products such as sheets and tubes with the requirement of high absorptance that can be produced through three-dimensional printing.
Finally, the dissertation concludes with recommendations on the methods to fabricate the suggested optical filters to improve thermophotovoltaic system efficiencies. The results presented in this dissertation will facilitate not only the manufacturing of materials but also the promising applications in solar thermal energy and optical systems.
ContributorsRamesh, Rajagopalan (Author) / Wang, Liping (Thesis advisor) / Azeredo, Bruno (Thesis advisor) / Phelan, Patrick (Committee member) / Yu, Hongbin (Committee member) / Rykaczewski, Konrad (Committee member) / Arizona State University (Publisher)
Created2022
Description
Communications around sustainability have been found to be incongruent with eliciting the transformative change required to address global climate change and its' repercussions. Recent research has been exploring storytelling in sustainability, specifically with an emphasis on reflexive and emancipatory methods. These methods encourage embracing and contextualizing complexity and intend to target entire cognitive hierarchies. This study explores the possibility of using emancipatory and reflexive storytelling as a tool to change attitudes pertaining to the Valley Metro Light Rail, an example of a complex sustainability mitigation effort. I explore this in four steps: 1) Conducted a pre-survey to gauge preexisting attitudes and predispositions; 2) Provided a narrative that uses storytelling methodologies of reflexivity and emancipation through a story about the light rail; 3) Conducted a post-survey to gauge attitude shift resulting from the narrative intervention; 4) Facilitated a focus group discussion to examine impact qualitatively. These steps intended to provide an answer to the question: How does emancipatory and reflexive storytelling impact affective, cognitive and conative attitudes regarding local alternative transportation? By using tripartite attitude model, qualitative and quantitative analysis this paper determines that reflexive and emancipatory storytelling impacts attitudinal structures. The impact is marginal in the survey response, though the shift indicated a narrowing of participant responses towards one another, indicative of participants subscribing to emancipation and reflexivity of their held attitudes. From the group discussion, it was evident from qualitative responses that participants engaged in emancipating themselves from their held attitudes and reflected upon them. In doing so they engaged in collaboration to make suggestions and suggest actions to help those with experiences that differed from their own. Though this research doesn’t provide conclusive evidence, it opens the door for future research to assess these methodologies as a tool to elicit shared values, beliefs and norms, which are necessary for collective action leading to transformative change in response to global climate change.
ContributorsSwanson, Jake Ryan (Author) / Roseland, Mark (Thesis advisor) / Larson, Kelli (Committee member) / Calhoun, Craig (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
Energy storage technologies are essential to overcome the temporal variability in renewable energy. The primary aim of this thesis is to develop reactor solutions to better analyze the potential of thermochemical energy storage (TCES) using non-stoichiometric metal oxides, for the multi-day energy storage application. A TCES system consists of a reduction reactor and an insulated MOx storage bin. The reduction reactor heats (to ~ 1100 °C) and partially reduces the MOx, thereby adding sensible and chemical energy (i.e., charging it) under reduced pO2 environments (~10 Pa). Inert gas removes the oxygen generated during reduction. The storage bin holds the hot and partially reduced MOx (typically particles) until it is used in an energy recovery device (i.e., discharge). Irrespective of the reactor heat source (here electrical), or the particle-inert gas flows (here countercurrent), the thermal reduction temperature and inert gas (here N2) flow minimize when the process approaches reversibility, i.e., operates near equilibrium. This study specifically focuses on developing a reduction reactor based on the theoretical considerations for approaching reversibility along the reaction path. The proposed Zigzag flow reactor (ZFR) is capable of thermally reducing CAM28 particles at temperatures ~ 1000 °C under an O2 partial pressure ~ 10 Pa. The associated analytical and numerical models analyze the reaction equilibrium under a real (discrete) reaction path and the mass transfer kinetic conditions necessary to approach equilibrium. The discrete equilibrium model minimizes the exergy destroyed in a practical reactor and identifies methods of maximizing the energy storage density () and the exergetic efficiency. The mass transfer model analyzes the O2 N2 concentration boundary layers to recommend sizing considerations to maximize the reactor power density. Two functional ZFR prototypes, the -ZFR and the -ZFR, establish the proof of concept and achieved a reduction extent, Δδ = 0.071 with CAM28 at T~950 °C and pO2 = 10 Pa, 7x higher than a previous attempt in the literature. The -ZFR consistently achieved > 100 Wh/kg during >10 h. runtime and the -ZFR displayed an improved = 130 Wh/kg during >5 h. operation with CAM28. A techno-economic model of a grid-scale ZFR with an associated storage bin analyzes the cost of scaling the ZFR for grid energy storage requirements. The scaled ZFR capital costs contribute < 1% to the levelized cost of thermochemical energy storage, which ranges from 5-20 ¢/kWh depending on the storage temperature and storage duration.
ContributorsGhotkar, Rhushikesh (Author) / Milcarek, Ryan (Thesis advisor) / Ermanoski, Ivan (Committee member) / Phelan, Patrick (Committee member) / Wang, Liping (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2023
Description
Understanding the dynamic interactions between humans and wildlife is essential to establishing sustainable wildlife-based ecotourism (WBE). Animal behavior exists within a complex feedback loop that affects overall ecosystem function, tourist satisfaction, and socioeconomics of local communities. However, the specific value that animal behavior plays in provisioning ecosystem services has not been thoroughly evaluated. People enjoy activities that facilitate intimate contact with animals, and there are many perceived benefits associated with these experiences, such as encouraging pro-environmental attitudes that can lead to greater motivation for conservation. There is extensive research on the effects that unregulated tourism activity can have on wildlife behavior, which include implications for population health and survival. Prior to COVID-19, WBE was developing rapidly on a global scale, and the pause in activity caused by the pandemic gave natural systems the chance to recover from environmental damage from over-tourism and provided insights into how tourism could be less impactful in the future. Until now it has been undetermined how changes in animal behavior can alter the relationships and socioeconomics of this multidimensional system. This dissertation provides a thorough exploration of the behavioral, ecological, and economic parameters required to model biosocial interactions and feedbacks within the whale watching system in Las Perlas Archipelago, Panama. Through observational data collected in the field, this project assessed how unmanaged whale watching activity is affecting the behavior of Humpback whales in the area as well as the socioeconomic and conservation contributions of the industry. Additionally, it is necessary to consider what a sustainable form of wildlife tourism might be, and whether the incorporation of technology will help enhance visitor experience while reducing negative impacts on wildlife. To better ascertain whether this concept of this integration would be favorably viewed, a sample of individuals was surveyed about their experiences about using technology to enhance their interactions with nature. This research highlights the need for more deliberate identification and incorporation of the perceptions of all stakeholders (wildlife included) to develop a less-impactful WBE industry that provides people with opportunities to establish meaningful relationships with nature that motivate them to help meet the conservation challenges of today.
ContributorsSurrey, Katie (Author) / Gerber, Leah (Thesis advisor) / Guzman, Hector (Committee member) / Minteer, Ben (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
A well-insulated dark conventional rooftop can be hotter than any other urban surface, including pavements. Since rooftops cover around 20 – 25% of most urban areas, their role in the urban heat island effect is significant. In general, buildings exchange heat with the surroundings in three ways: heat release from the cooling/heating system, air exchange associated with exfiltration and relief air, and heat transfer between the building envelope and surroundings. Several recent studies show that the building envelope generates more heat release into the environment than any other building component.Current advancements in material science have enabled the development of materials and coatings with very high solar reflectance and thermal emissivity, and that can alter their radiative properties based on surface temperature. This dissertation is an effort to quantify the impact of recent developments in such technologies on urban air. The current study addresses three specific unresolved topics: 1) the relative importance of rooftop solar reflectance and thermal emissivity, 2) the role of rooftop radiative properties in different climates, and 3) the impact of temperature-adaptive exterior materials/coatings on building energy savings and urban cooling. The findings from this study show that the use of rooftop materials with solar reflectance above 0.9 maintain the surface temperature below ambient air temperature most of the time, even when the materials have conventional thermal emissivity (0.9). This research has demonstrated that for hot cities, rooftops with high solar reflectance and thermal emittance maximize building energy savings and always cool the surrounding air. For moderate climate regions, high solar reflectance and low thermal emittance result in the greatest building energy cost savings. This combination of radiative properties cools the air during the daytime and warms it at night. Finally, this research found that temperature-adaptive materials could play a significant role in reducing utility costs for poorly insulated buildings, but that they heat the surrounding air in the winter, irrespective of the rooftop insulation.
Through the detailed analysis of building façade radiative properties, this dissertation offers climate-specific design guidance that can be used to simultaneously optimize energy costs while minimizing adverse warming of the surrounding environment.
ContributorsPrem Anand Jayaprabha, Jyothis Anand (Author) / Sailor, David (Thesis advisor) / Phelan, Patrick (Thesis advisor) / Huang, Huei-Ping (Committee member) / Wang, Liping (Committee member) / Yeom, Dongwoo Jason (Committee member) / Arizona State University (Publisher)
Created2022
Description
Scientists are entrusted with developing novel molecular strategies for effective prophylactic and therapeutic interventions. Antivirals are indispensable tools that can be targeted at viral domains directly or at cellular domains indirectly to obstruct viral infections and reduce pathogenicity. Despite their transformative potential in healthcare, to date, antivirals have been clinically approved to treat only 10 out of the greater than 200 known pathogenic human viruses. Additionally, as obligate intracellular parasites, many virus functions are intimately coupled with host cellular processes. As such, the development of a clinically relevant antiviral is challenged by the limited number of clear targets per virus and necessitates an extensive insight into these molecular processes. Compounding this challenge, many viral pathogens have evolved to evade effective antivirals. Therefore, a means to develop virus- or strain-specific antivirals without detailed insight into each idiosyncratic biochemical mechanism may aid in the development of antivirals against a larger swath of pathogens. Such an approach will tremendously benefit from having the specific molecular recognition of viral species as the lowest barrier. Here, I modify a nanobody (anti-green fluorescent protein) that specifically recognizes non-essential epitopes (glycoprotein M-pHluorin chimera) presented on the extra virion surface of a virus (Pseudorabies virus strain 486). The nanobody switches from having no inhibitory properties (tested up to 50 μM) to ∼3 nM IC50 in in vitro infectivity assays using porcine kidney (PK15) cells. The nanobody modifications use highly reliable bioconjugation to a three-dimensional wireframe deoxyribonucleic acid (DNA) origami scaffold. Mechanistic studies suggest that inhibition is mediated by the DNA origami scaffold bound to the virus particle, which obstructs the internalization of the viruses into cells, and that inhibition is enhanced by avidity resulting from multivalent virus and scaffold interactions. The assembled nanostructures demonstrate negligible cytotoxicity (<10 nM) and sufficient stability, further supporting their therapeutic potential. If translatable to other viral species and epitopes, this approach may open a new strategy that leverages existing infrastructures – monoclonal antibody development, phage display, and in vitro evolution - for rapidly developing novel antivirals in vivo.
ContributorsPradhan, Swechchha (Author) / Hariadi, Rizal (Thesis advisor) / Hogue, Ian (Committee member) / Varsani, Arvind (Committee member) / Chen, Qiang (Committee member) / Arizona State University (Publisher)
Created2022
Description
Monkeypox virus (MPXV) is an orthopoxvirus that causes smallpox-like disease and has up to a 10% mortality rate, depending on the infectious strain. The global eradication of the smallpox virus has led to the decrease in smallpox vaccinations, which has led to a drastic increase in the number of human MPXV cases. MPXV has been named the most important orthopoxvirus to infect humans since the eradication of smallpox and has been the causative agent of the 2022 world-wide MPXV outbreak. Despite being highly pathogenic, MPXV contains a natural truncation at the N-terminus of its E3 homologue. Vaccinia virus (VACV) E3 protein has two domains: an N- terminus Z-form nucleic acid binding domain (Z-BD) and a C-terminus double stranded RNA binding domain (dsRBD). Both domains are required for pathogenesis, interferon (IFN) resistance, and protein kinase R (PKR) inhibition. The N-terminus is required for evasion of Z-DNA binding protein 1 (ZBP1)-dependent necroptosis. ZBP1 binding to Z- form deoxyribonucleic acid/ribonucleic acid (Z-DNA/RNA) leads to activation of receptor-interacting protein kinase 3 (RIPK3) leading to mixed lineage kinase domain- like (MLKL) phosphorylation, aggregation and cell death. This study investigated how different cell lines combat MPXV infection and how MPXV has evolved ways to circumvent the host response. MPXV is shown to inhibit necroptosis in L929 cells by degrading RIPK3 through the viral inducer of RIPK3 degradation (vIRD) and by inhibiting MLKL aggregation. Additionally, the data shows that IFN treatment efficiently inhibits MPXV replication in a ZBP1-, RIPK3-, and MLKL- dependent manner, but independent of necroptosis. Also, the data suggests that an IFN inducer with a pancaspase or proteasome inhibitor could potentially be a beneficial treatment against MPXV infections. Furthermore, it reveals a link between PKR and pathogen-induced necroptosis that has not been previously described.
ContributorsWilliams, Jacqueline (Author) / Jacobs, Bertram (Thesis advisor) / Langland, Jeffrey (Committee member) / Lake, Douglas (Committee member) / Varsani, Arvind (Committee member) / Arizona State University (Publisher)
Created2022
Description
Siloxane, a common contaminant present in biogas, is known for adverse effects on cogeneration prime movers. In this work, the solid oxide fuel cell (SOFC) nickel-yttria stabilized zirconia (Ni-YSZ) anode degradation due to poisoning by siloxane was investigated. For this purpose, experiments with different fuels, different deposition substrate materials, different structure of contamination siloxane (cyclic and linear) and entire failure process are conducted in this study. The electrochemical and material characterization methods, such as Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscope- Wavelength Dispersive Spectrometers (SEM-WDS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and Raman spectroscopy, were applied to investigate the anode degradation behavior. The electrochemical characterization results show that the SOFCs performance degradation caused by siloxane contamination is irreversible under bio-syngas condition. An equivalent circuit model (ECM) is developed based on electrochemical characterization results. Based on the Distribution of Relaxation Time (DRT) method, the detailed microstructure parameter changes are evaluated corresponding to the ECM results. The results contradict the previously proposed siloxane degradation mechanism as the experimental results show that water can inhibit anode deactivation. For anode materials, Ni is considered a major factor in siloxane deposition reactions in Ni-YSZ anode. Based on the results of XPS, XRD and WDS analysis, an initial layer of carbon deposition develops and is considered a critical process for the siloxane deposition reaction. Based on the experimental results in this study and previous studies about siloxane deposition on metal oxides, the proposed siloxane deposition process occurs in stages consisting of the siloxane adsorption, initial carbon deposition, siloxane polymerization and amorphous silicon dioxide deposition.
ContributorsTian, Jiashen (Author) / Milcarek, Ryan J. (Thesis advisor) / Muhich, Christopher (Committee member) / Wang, Liping (Committee member) / Phelan, Patrick (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2022
Description
The space industry is rapidly expanding, and components are getting increasinglysmaller leading to the prominence of cubesats. Cubesats are satellites from about coffee
mug size to cereal box size. The challenges of shortened timeline and smaller budgets for
smaller spacecraft are also their biggest advantages. This benefits educational missions
and industry missions a like but can burden teams to be smaller or have less experience.
Thermal analysis of cubesats is no exception to these burdens which is why this thesis
has been written to provide a guide for conducting the thermal analysis of a cubesat using
the Deployable Optical Receiver Aperture (DORA) mission as an example. Background
on cubesats and their role in the space industry will be examined. The theoretical side of
heat transfer necessary for conducting a thermal analysis will be explored. The DORA
thermal analysis will then be conducted by constructing a thermal model in Thermal
Desktop software from the ground up. Insight to assumptions for model construction to
move accurately yet quickly will be detailed. Lastly, this fast and quick method will be
compared to a standard finite element mesh model to show quality results can be
achieved in significantly less time.
ContributorsAdkins, Matthew Thomas (Author) / Phelan, Patrick (Thesis advisor) / Jacobs, Danny (Thesis advisor) / Wang, Liping (Committee member) / Bowman, Judd (Committee member) / Arizona State University (Publisher)
Created2022
Description
Radiation heat transfer can surpass blackbody limit when distance between the hot emitter and cold receiver is less than the characteristic wavelength of electromagnetic radiation. The enhanced radiation heat transfer achieved is also called near-field radiation heat transfer. Several theoretical and experimental studies have demonstrated enhancement in near-field radiation heat transfer for isotropic materials such as silicon carbide (SiC), undoped and doped Si. The enhancement achieved however is narrow-banded. Significant improvement in radiation heat transfer is necessary to satisfy some of the energy demands. So, there is a growing interest to use hyperbolic materials because of its enhancement due to propagating modes. The main objective of the current thesis project is to investigate the control of hyperbolic bands using boron nitride nanotubes (nanostructure of hexagonal boron nitride) for near-field radiative heat transfer. Optical properties of boron nitride nanotubes are calculated using Maxwell-Garnet’s effective medium theory and its corresponding hyperbolic bands are identified. It is observed that the boron nitride nanotubes have only one hyperbolic band located at higher frequencies. Preliminary comparisons of the near-field radiative heat flux calculations with literature are performed using a more general 4×4 transfer matrix method. Due to its high computational time, anisotropic thin film optics is used to calculate near-field radiative heat transfer. Factors contributing to enhancement is investigated. In the end, Spectral allocation ratio, the ratio of heat flux contributed from higher frequencies to the heat flux contributed from lower frequencies is calculated to assess the contribution of each hyperbolic band to total heat flux.
ContributorsRajan, Vishwa Krishna (Author) / Wang, Liping (Thesis advisor) / Phelan, Patrick (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2022