Matching Items (35)
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- All Subjects: Materials Science
- All Subjects: race
- Creators: Chan, Candace
Description
Dealloying, the selective dissolution of an elemental component from an alloy, is an important corrosion mechanism and a technological significant means to fabricate nanoporous structures for a variety of applications. In noble metal alloys, dealloying proceeds above a composition dependent critical potential, and bi-continuous structure evolves "simultaneously" as a result of the interplay between percolation dissolution and surface diffusion. In contrast, dealloying in alloys that show considerable solid-state mass transport at ambient temperature is largely unexplored despite its relevance to nanoparticle catalysts and Li-ion anodes. In my dissertation, I discuss the behaviors of two alloy systems in order to elucidate the role of bulk lattice diffusion in dealloying. First, Mg-Cd alloys are chosen to show that when the dealloying is controlled by bulk diffusion, a new type of porosity - negative void dendrites will form, and the process mirrors electrodeposition. Then, Li-Sn alloys are studied with respect to the composition, particle size and dealloying rate effects on the morphology evolution. Under the right condition, dealloying of Li-Sn supported by percolation dissolution results in the same bi-continuous structure as nanoporous noble metals; whereas lattice diffusion through the otherwise "passivated" surface allows for dealloying with no porosity evolution. The interactions between bulk diffusion, surface diffusion and dissolution are revealed by chronopotentiometry and linear sweep voltammetry technics. The better understanding of dealloying from these experiments enables me to construct a brief review summarizing the electrochemistry and morphology aspects of dealloying as well as offering interpretations to new observations such as critical size effect and encased voids in nanoporous gold. At the end of the dissertation, I will describe a preliminary attempt to generalize the morphology evolution "rules of dealloying" to all solid-to-solid interfacial controlled phase transition process, demonstrating that bi-continuous morphologies can evolve regardless of the nature of parent phase.
ContributorsChen, Qing (Author) / Sieradzki, Karl (Thesis advisor) / Friesen, Cody (Committee member) / Buttry, Daniel (Committee member) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2013
Description
This project explores the function of art pedagogy as a tool for social justice, especially for youth. As a student pursuing the study of both education and social justice, the experience I've had in my life with art is hugely connected with these themes. In this exploratory project, I examined different creative youth development programs through the perspectives of art educators, exploring how, pedagogically, they contribute to the formation of social justice in the communities and students they serve through the teaching and creation of art. I began with the research question, how do different creative youth development contribute to social justice in the communities and students they serve using art as a pedagogical approach? My goal in asking this question was to develop a picture of the art pedagogies employed in these programs, and their relation to the broader topic of social justice. Then, after reviewing the literature related to this topic, which is outlined in the next section, I identified three components of social justice related to art education: self expression, cultural identity exploration, and critical engagement. All of these concepts emerged time and time again when reviewing literature about art education and youth, and also art and social justice. Focusing on these concepts, I explored the question of how these components of social justice are explored in particular creative youth development programs. My goal in asking these questions is to develop a picture of the art pedagogies employed in these programs, and their relation to the broader topic of social justice. In order to ask these questions, it was important I access the art educators behind art programs whose impact is connected to art and social justice. Through their perspectives, I was able to gain incite about the design, implementation, and outcomes of art pedagogy. I found that these programs, in employing art pedagogies, were powerful tools in helping youth connect to themselves and their communities, aiding in the production of social justice.
ContributorsFarrier, Merry Elise (Author) / Swadener, Elizabeth (Thesis director) / Gonzales, Vanna (Committee member) / Barrett, The Honors College (Contributor) / School of Social Transformation (Contributor) / Division of Teacher Preparation (Contributor)
Created2015-05
Description
Wilson and Kelling's (1982) broken windows theory (BWT) says that disorder causes crime at the neighborhood level. More specifically, this theory posits that perceptions of disorder increase fear of crime, which then reduces community involvement, making crime more likely. Recent studies show that race plays a pivotal role in people's perceptions of disorder. In short, people tend to associate race with low socioeconomic status, high arrest rates, and lack of policing. Therefore, race plays a central role in the BWT framework as it is linked to perceptions of disorder and crime. However, ethnicity is less well understood when analyzing the perceptions of disorder. To explore this further, the current study examines Latino responses regarding safety and ethnicity to a photograph depicting a religious mural of importance for the Mexican community (La Virgen de Guadalupe). This paper qualitatively analyzes a sample of 299 survey responses of undergraduate Latino students to better understand how Latinos recognize and identify their own culture/heritage and disorder. Implications for understanding ethnicity and broken windows theory are discussed.
ContributorsEsparza, Karla N (Author) / Wallace, Danielle (Thesis director) / Ready, Justin (Committee member) / Lyons, Christopher (Committee member) / Barrett, The Honors College (Contributor) / School of Social Transformation (Contributor) / School of Criminology and Criminal Justice (Contributor)
Created2015-05
Description
Objective: This study examined how the belief (internalization) in the model minority myth of achievement orientation and of unrestricted mobility relates to one’s social awareness of racial inequity and inequality in society (critical consciousness) amongst Asian American college students. Methods: Participants (N = 275, 67.7% female, M_age = 22.35) were recruited from Asian American ethnic studies classes, clubs and organizations and completed an online cross-sectional survey. Results: Results indicated that internalization of achievement orientation significantly correlated with levels of racial critical consciousness while unrestricted mobility did not. Conclusion: These findings extend research exploring the correlates of critical consciousness on internalization of racial stereotypes for Asian Americans.
ContributorsMatriano, Ronae (Author) / Yoo, Hyung Chol (Thesis director) / Atkin, Annabelle (Committee member) / Li, Wei (Committee member) / School of Social Transformation (Contributor) / School of Life Sciences (Contributor) / Hugh Downs School of Human Communication (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This research examines popular culture’s influence on public perceptions of criminality and criminal justice reform. I have a two-pronged focus: first, I examine how specific cultural texts present criminal behavior, policing, and the criminal justice system; second, I show how these texts’ portrayals of criminal behavior, policing, and the criminal justice system, influence public perceptions about criminal justice reform. Throughout the era of filmmaking and the heightened growth of media consumption, the representation of crime and criminals has had a profound presence in film and media, but with little guidance or fact-checking from the general public and its creators (Welsh, Fleming and Dowler, 2011). Despite this, public perception of the law and reality continues to find its line being constantly blurred, with legal theorist, Richard Sherwin asserting that “The majority of American citizens form their opinions about the criminal justice system through the mass media, and more often than not, from fictional accounts of the trial process” (Alford, 2000). This in turn leads to a culture of preconceived notions that later form into political and social opinions with an unknown negative bias against reform efforts and legal accuracy (Sarat, 2015).
ContributorsMartinez, Maria Priscilla (Author) / Ingram-Waters, Mary (Thesis director) / Mexica, Cuauhtemoc (Committee member) / School of Social Transformation (Contributor, Contributor) / Department of Psychology (Contributor) / School of Politics and Global Studies (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Do more diverse teams create better outcomes, creatively and fiscally? Why do heterogeneous groups think more innovatively and create products that reach a wider audience? Diverse teams bring unique perspectives that force individuals to reimagine their world views and question what they know. This thesis focuses on the benefits of increased racial and gender diversity in the workplace. There is a dramatic difference in the number of women and people of color in tech companies generally, in STEM roles, and in leadership roles. The benefits of diverse teams (along all axis) is indisputable, yet companies still fight diversifying their employee base. Diversity in the workplace dramatically impacts the bottom line, but it is also incredibly important from a human rights perspective. The first step to reflecting the population's diversity ratio at all levels of business is educating the future leaders of America to its importance, both as a social justice initiative and a capitalistic one as well. I created and hosted a panel with local tech entrepreneurs and investors to discuss gender diversity, the struggles being a woman in business and solutions moving forward.
ContributorsRobinson, Sasha Raquel (Author) / Mokwa, Michael (Thesis director) / Eaton, John (Committee member) / School of Social Transformation (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Solid-state lithium-ion batteries are a major area of research due to their increased safety characteristics over conventional liquid electrolyte batteries. Lithium lanthanum zirconate (LLZO) is a promising garnet-type ceramic for use as a solid-state electrolyte due to its high ionic conductivity. The material exists in two dierent phases, one that is cubic in structure and one that is tetragonal. One potential synthesis method that results in LLZO in the more useful, cubic phase, is electrospinning, where a mat of nanowires is spun and then calcined into LLZO. A phase containing lanthanum zirconate (LZO) and amorphous lithium occursas an intermediate during the calcination process. LZO has been shown to be a sintering aid for LLZO, allowing for lower sintering temperatures. Here it is shown the eects of internal LZO on the sintered pellets. This is done by varying the 700C calcination time to transform diering amounts of LZO and LLZO in electrospun nanowires, and then using the same sintering parameters for each sample. X-ray diraction was used to get structural and compositional analysis of both the calcined powders and sintered pellets. Pellets formed from wires calcined at 1 hour or longer contained only LLZO even if the calcined powder had only undergone the rst phase transformation. The relative density of the pellet with no initial LLZO of 61.0% was higher than that of the pellet with no LZO, which had a relative density of 57.7%. This allows for the same, or slightly higher, quality material to be synthesized with a shorter amount of processing time.
ContributorsLondon, Nathan Harry (Author) / Chan, Candace (Thesis director) / Tongay, Sefaattin (Committee member) / Department of Physics (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This is an analysis of broad racial discourse through a critical race theory: Responsibility Avoidance Discourse (RAD). RAD is coded English that communicates meaning through connotation, avoidance, and implication as a means of securing its main purposes: enforcing white supremacy, obscuring inequality, and hindering significant racial progress. RAD is extremely effective at directing discussion away from arguments that might induce self-reflexivity or question white privilege. It focuses on discrediting others as a means of legitimizing whiteness. I analyze examples of it from a variety of sources—from political discourse to media coverage and social media trends—to demonstrate its manifestations throughout society.
ContributorsClarke, Ty Larson (Author) / Bebout, Lee (Thesis director) / Spanierman, Lisa (Committee member) / School of Social Transformation (Contributor) / W. P. Carey School of Business (Contributor) / Department of English (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Topological insulators with conducting surface states yet insulating bulk states have generated a lot of interest amongst the physics community due to their varied characteristics and possible applications. Doped topological insulators have presented newer physical states of matter where topological order co&ndashexists; with other physical properties (like magnetic order). The electronic states of these materials are very intriguing and pose problems and the possible solutions to understanding their unique behaviors. In this work, we use Electron Energy Loss Spectroscopy (EELS) – an analytical TEM tool to study both core&ndashlevel; and valence&ndashlevel; excitations in Bi2Se3 and Cu(doped)Bi2Se3 topological insulators. We use this technique to retrieve information on the valence, bonding nature, co-ordination and lattice site occupancy of the undoped and the doped systems. Using the reference materials Cu(I)Se and Cu(II)Se we try to compare and understand the nature of doping that copper assumes in the lattice. And lastly we utilize the state of the art monochromated Nion UltraSTEM 100 to study electronic/vibrational excitations at a record energy resolution from sub-nm regions in the sample.
ContributorsSubramanian, Ganesh (Author) / Spence, John (Thesis advisor) / Jiang, Nan (Committee member) / Chen, Tingyong (Committee member) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2013
Description
Recent advancements in the field of light wavefront engineering rely on complex 3D metasurfaces composed of sub-wavelength structures which, for the near infrared range, are challenging to manufacture using contemporary scalable micro- and nanomachining solutions. To address this demand, a novel parallel micromachining method, called metal-assisted electrochemical nanoimprinting (Mac-Imprint) was developed. Mac-Imprint relies on the catalysis of silicon wet etching by a gold-coated stamp enabled by mass-transport of the reactants to achieve high pattern transfer fidelity. This was realized by (i) using nanoporous catalysts to promote etching solution diffusion and (ii) semiconductor substrate pre-patterning with millimeter-scale pillars to provide etching solution storage. However, both of these approaches obstruct scaling of the process in terms of (i) surface roughness and resolution, and (ii) areal footprint of the fabricated structures. To address the first limitation, this dissertation explores fundamental mechanisms underlying the resolution limit of Mac-Imprint and correlates it to the Debye length (~0.9 nm). By synthesizing nanoporous catalytic stamps with pore size less than 10 nm, the sidewall roughness of Mac-Imprinted patterns is reduced to levels comparable to plasma-based micromachining. This improvement allows for the implementation of Mac-Imprint to fabricate Si rib waveguides with limited levels of light scattering on its sidewall. To address the second limitation, this dissertation focuses on the management of the etching solution storage by developing engineered stamps composed of highly porous polymers coated in gold. In a plate-to-plate configuration, such stamps allow for the uniform patterning of chip-scale Si substrates with hierarchical 3D antireflective and antifouling patterns. The development of a Mac-Imprint system capable of conformal patterning onto non-flat substrates becomes possible due to the flexible and stretchable nature of gold-coated porous polymer stamps. Understanding of their mechanical behavior during conformal contact allows for the first implementation of Mac-Imprint to directly micromachine 3D hierarchical patterns onto plano-convex Si lenses, paving the way towards scalable fabrication of multifunctional 3D metasurfaces for applications in advanced optics.
ContributorsSharstniou, Aliaksandr (Author) / Azeredo, Bruno (Thesis advisor) / Chan, Candace (Committee member) / Rykaczewski, Konrad (Committee member) / Petuskey, William (Committee member) / Chen, Xiangfan (Committee member) / Arizona State University (Publisher)
Created2022