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PULSED LASER DEPOSITION AND OPTIMIZATION OF LSGM AND LSCF THIN FILMS FOR SOLID OXIDE FUEL CELL APPLICATIONS
No full textThe performance and durability of solid oxide fuel cells (SOFCs) are critically governed by the structural and chemical coherency of the hetero-interfaces between oxygen ion-conducting electrolytes and electronically conducting electrodes. In particular, realizing coherent and chemically stable interfaces between La₀.₈Sr₀.₂Ga₀.₈Mg₀.₂O₃−δ (LSGM), a fast oxygen-ion conductor, and (La₀.₆Sr₀.₄)₀.₉₅Co₀.₂Fe₀.₈O₃−δ (LSCF), a mixed ionic-electronic conductor, is critical for minimizing interfacial resistance and enabling high-efficiency energy conversion.A major challenge in solid-state fuel cells arises from the potential interdiffusion of cations across electrolyte/electrode interfaces, which can lead to the formation of undesired secondary phases and degraded ionic/electronic transport properties. Therefore, precise interface engineering is essential to preserve the functional stability of both layers. Despite the technological importance, detailed experimental studies remain lacking, especially on the epitaxial growth and hetero-interface structure of LSGM and LSCF heterostructures using Pulsed Laser Deposition (PLD). In this work, we systematically optimized PLD growth conditions for single-crystalline LSGM and LSCF thin films on SrTiO₃ (001) substrates, aiming to establish a coherent and well-defined hetero-interface suitable for fundamental studies of interfacial phenomena under the fuel cell operating condition. X-ray diffraction (XRD) analysis revealed that LSGM films grown at 800 °C and 150 mTorr of oxygen partial pressure exhibited a lattice parameter of 3.909 Å (0.017) with a full-width-at-half-maximum (FWHM) of 0.169°, while LSCF films grown under optimized conditions showed a lattice parameter of 3.916 Å (0.021) and an FWHM of 0.072°, indicating high crystallinity and epitaxial alignment. As a result, the successful fabrication of LSGM/LSCF heterostructure exhibited distinct XRD peaks from both layers, suggesting layered epitaxial growth without significant interdiffusion or secondary phase formation under the optimized conditions. This study provides a reproducible route for the coherent integration of LSGM electrolytes and LSCF electrodes via PLD, offering a model platform for exploring interfacial transport, defect chemistry, and long-term stability — essential aspects for the development of next-generation, high-performance SOFC devices
Polarimetric Doppler Spectra in Southern Plains Tornadoes Computed from Mobile Radar Data
No full textDoppler wind velocity estimates depend on the assumption that scatterers in the atmosphere are moving at the same velocity as their surrounding air molecules, as the radio waves used in weather radars do not significantly backscatter off air molecules. Most of the time, this assumption is valid, but in tornadoes, wind speeds become high and the airflow exhibits substantial curvature. Larger and more massive scatterers accelerate more slowly under the force of the wind and are also subject to an increased centrifugal force. Thus, these scatterers do not move at the same velocity as the wind, and velocity estimates can be subject to large errors/biases. In order to study tornado dynamics, errors in wind fields must be diagnosed and minimized. This can be accomplished by spectral analysis of raw, dual-polarization, in-phase and quadrature (I/Q) data. Since 2018, efforts have been made using the University of Oklahoma's rapid-scan, X-band, polarimetric, mobile Doppler radar to collect I/Q data in tornadoes and verify these velocity errors. Through Fourier analysis of I/Q signals, dual-polarization spectral densities (DPSDs) can be computed, which leverage the distinct polarimetric characteristics of rain and debris to separate their respective motions. In 2023 and 2024, RaXPol collected I/Q data from within three tornadic vortices, with the last one, on May 23, 2024, being the most comprehensive. This dataset was collected in an EF-2 tornado using a scanning strategy involving multiple low-level scans through the debris cloud of the tornado. The radar employed a slow azimuthal rotation (6 degrees per second) with sector scanning, achieving over 650 pulses per degree of azimuth. The spectra were evaluated for quality using a convergence metric that optimizes parameters for DPSD computation and assesses the requirement for slow scanning. With computed DPSDs and an automated fuzzy logic debris classification algorithm (DCA), spectra were analyzed, and areas of strong velocity bias were identified, consistent with numerical simulations. These results demonstrate the potential for improved tornado dynamics retrieval through spectral polarimetric analysis
All for Catholicism and Family: The De la Torre Family During The Cristero Movement 1900-1980
Full text linkMy thesis focuses on the De la Torre family, an extraordinary family, who participated inthe Cristero War in the Sonora Arizona border region. The Cristero War (1926-1929) was a conflict between the Mexican government and the Catholic Church in Mexico. The family was frustrated with the Mexican government’s enforcement of anti-clerical laws in the Constitution of 1917, the deportation of Catholic clergy, and shutting churches down. They were involved in Cristero organizations such as the Asociación Católica de la Juventud (ACJM) and the Liga Nacional de la Libertad Religiosa. The De la Torre family part took in, rallied, and took part a Cristero combat group in hopes to restore celebrating Catholicism in Mexico. The thesis argues that Catholic parents like the De la Torre parents nurtured the value of martyrdom in their children. When those children became adults, they were willing to risk their lives for the Catholic faith. This study expands the narrative of the Cristero War by including the family perspective in the U.S.-Mexico Borderlands. The thesis spans three chapters, each focusing on one member of the De la Torre family. The first chapter focuses on the eldest daughter, Maria de la Torre, and argues that women like Maria were representatives for their families in the Catholic communities. Her martyrdom shows her sacrifice of social life by never marrying or having children. The second chapter centers on Alfonso de la Torre and how he highlighted Catholic masculinity. His martyrdom falls within the traditional view of giving up one’s life for the Catholic faith. The last chapter analyzes Ignacio de la Torre’s life and highlights the relationship between the Church and state. His martyrdom reflects traditional martyrdom and a loss of personal autonomy to fulfill the Church’s needs. The thesis relies on oral histories, family correspondence, family portraits, and political cartoons to narrate how Catholic families endured during the Cristero War
Gamifying climate content to enhance climate literacy: Opportunities for adult learners
Full text linkFinancial support was provided by the University of Oklahoma Libraries' Open Access Fund.Educational games are well suited to tackle the complexity of challenges like climate change because they can simulate complex systems. The purpose of this study is to build upon the work of previous scholars to (a) identify the opportunities associated with the gamifying of climate change content for adult learners and (b) propose how games can further enhance the functional climate literacy of adults. To our knowledge, there is not a review of peer-reviewed literature that assesses knowledge gained or provides a framework for designing these games. We explored the observed impacts of 48 unique climate change educational games and synthesized the work of 53 peer-reviewed journal articles. In general, we noted the games contributed to an increase in knowledge about climate change. Games that implemented a combination of hands-on and digital elements to explore the impacts of future decisions appeared to be the most impactful for increasing climate change knowledge and fostering an action-oriented mindset following the game. Our study also noted that these climate change educational games are primarily designed and implemented for youth and college audiences. This finding is in line with previous research and continues to highlight the need for climate change educational games for adult learners that allow them to bring in their own life experiences and learn how to solve problems that relate to their everyday lives. As a result, we developed a multi-phase framework to guide the development and implementation of climate change educational games for adult audiences.Ye
INVESTIGATING GRADUATE TEACHING ASSISTANTS’ MISCONCEPTIONS IN CHEMICAL EQUILIBRIUM: IMPLICATIONS FOR PEDAGOGICAL SUPPORT
Full text linkThis study examines the misconceptions about chemical equilibrium held by first-year graduate teaching assistants (GTAs) in a general chemistry course (CHEM 1). To address the research questions, a Chemical Equilibrium Diagnostic Test (CEDT) and a targeted mini-lecture were developed and implemented. Data were collected from two separate cohorts in Spring 2023 (N=10) and Fall 2023 (N=11) through pre- and post-assessments using the CEDT, classroom observations, and follow-up interviews.Pre-assessment scores averaged 7.10/14 in Spring 2023 and 5.82/14 in Fall 2023, revealing widespread misconceptions, such as misapplying thermodynamic reasoning to predict changes in reaction rate, confusing mass with concentration, and incorrectly applying Le Châtelier’s Principle. Among these, 60% of Spring 2023 GTAs incorrectly believed that lowering the temperature shifts an exothermic equilibrium backward, and 36% of Fall 2023 GTAs believed that removing a reactant would cause a passive decrease in another reactant. Misconceptions were also observed in GTAs’ instructional practices during laboratory sessions. For example, one GTA defined equilibrium as the point at which the concentrations of reactants and products are equal, while another incorrectly stated that decreasing pressure shifts equilibrium toward the side with fewer gas molecules. These findings suggest that, without structured guidance, GTAs may unintentionally introduce or reinforce student misconceptions during lab instruction. Post-assessment scores improved in both cohorts, particularly among mini-lecture attendees. In Spring, attendees improved by 2.5 points while non-attendees by 1.5; in Fall, attendees improved by 2.0 points and non-attendees by 0.66. Although mixed ANOVA results did not show a statistically significant interaction between mini-lecture attendance and score gains, item-level analyses revealed that attendees more frequently corrected specific misconceptions and adopted more precise, IUPAC-aligned terminology. Interview data (N=4) indicated that GTAs found both the diagnostic test and the mini-lecture helpful. Participants recommended regular content reviews, stronger alignment between lab and lecture materials, and standardized instructional resources to reduce preparation time. The findings contribute to the broader field of TA training by demonstrating that brief and targeted pedagogical interventions can meaningfully improve GTAs’ conceptual understanding and instructional delivery of foundational chemistry topics
INVESTIGATING THE PROBLEM WITH PROBLEMS: PRESERVICE MATHEMATICS TEACHERS’ UNDERSTANDING OF PROBLEMS AND PROBLEM SOLVING
Full text linkProblem solving is a key component of mathematics education. Waves of educational reform have focused on the problem-solving aspect within the K-12 educational setting. Yet, the teacher plays a critical role in establishing the problem-solving environment of the classroom. Therefore, preservice secondary mathematics teachers (PSMTs) must examine their understanding of problem solving and tasks that engage their future students in problem solving. This research project aimed to explore and interpret the meanings that PSMTs associate with problem-solving tasks. By examining their experiences with these tasks and the connections they make, this study sought to understand how PSMTs determine the problem-solving criteria they will apply in their future classrooms and investigate the cognitive structures underlying their decision-making within the context of mathematics education. This study centered around questions involving PSMTs' understanding of problems, problem solving, and their criteria for a worthwhile task. This study was a case study design with qualitative data collection within a first mathematics methods course. Participants were three PSMTs enrolled in their first mathematics methods course. Data collection methods involved interviews and analysis of problem-solving tasks and assignments. Common themes for understanding problems were solvable and thinking/sense-making. Problem solving is centralized on uncomfortableness and connecting prior knowledge with new information. The themes involving criteria for worthwhile tasks were mathematical connections, collaboration, and student engagement. Based on the findings of this study, there is a need for mathematics educational institutions to create opportunities for PSMTs to evaluate tasks and refine their criteria for worthwhile tasks. Both mathematics methods courses and content courses should have activities to edit tasks to meet the criteria for worthwhile tasks
Melt-based additive manufacturing of refractory metals and alloys: Experiments and modeling
Full text linkFinancial support was provided by the University of Oklahoma Libraries' Open Access Fund.Refractory metals and alloys possess unique properties, such as high melting points and excellent mechanical stability at elevated temperatures, making them attractive for aerospace, nuclear, and other demanding industries. However, fabrication of these materials using traditional manufacturing techniques is challenging due to their high melting points and intrinsic brittleness. Additive manufacturing (AM) techniques provide an approach to mitigate some of these challenges, but systematic insights into their process parameters, microstructure control, and mechanical performance remain fragmented in the literature. This paper provides an overview of the challenges and future prospects associated with melt-based AM of refractory metals and alloys from the perspectives of experiments, physics-based models, and data-driven approaches. Our review concludes by summarizing the frontiers in the field and highlighting the future developments necessary to enable efficient AM fabrication of refractory metals and alloys.Ye
Understanding Strain Effects on IrO2 for Oxygen Evolution Electrocatalysis
Full text linkUnderstanding how strain influences the electronic and geometric properties of surface active sites and the activity and stability of the iridium oxide-catalyzed oxygen evolution reaction (OER) has significant scientific and technological implications for designing next-generation electrocatalysts. In this study, we use density functional theory (DFT) calculations to systematically investigate the effect of compressive and tensile biaxial surface strains on the OER activity and stability of the IrO2(110), IrO2(100), and IrO2(101) surfaces. Our results reveal significant changes in the adsorption free energies of the OER intermediates due to strain, which in turn influences the OER activity. Furthermore, we evaluate how the electronic structure of IrO2 surface atoms varies with strain, leading to a fundamental theoretical understanding of strain effects. Our theoretical analysis further accounts for the effects of strain in the presence of a nearby surface Ir vacancy and high surface oxygen coverage, representing realistic surfaces under OER conditions. This work expands the current understanding of strain-assisted activity and stability enhancements in OER catalysts, paving the way for the development of strain-engineered electrocatalysts.Ye
Language teacher associations as a nexus of research and practice: A collaborative autoethnography
Full text linkFinancial support was provided by the University of Oklahoma Libraries' Open Access Fund.Due to what has been identified as an increasing divide between language teaching practice and research, there exists a growing need to identify unique ways of building sustained collaborations between researchers and teachers. This is particularly needed in the context of world languages (WL) teaching in the United States, which faces numerous challenges arising from pervasive macro-level forces at the state and national levels. One promising means of addressing this need is teachers' and researchers’ collective engagement with language teacher associations. Taking a collaborative autoethnographic approach, this qualitative study sought to understand how individuals of varied and overlapping roles (e.g., researchers, WL teachers, teacher educators, students, members and leaders of a language teaching association) perceived the structure and mutually contributory nature of one state level teacher association in the United States. Findings indicated that WL teachers and researchers both contributed to and received contributions from the language teacher association in diverse ways. In addition, the findings revealed how the rationale and type of bidirectional contributions were shaped by the constraints and affordances of the state context. The study illuminates the potential of language teacher associations in mediating and sustaining such a research-practice nexus and collective agency in challenging contexts. Implications for language teachers, researchers, teacher educators, and language teacher associations are discussed.Ye
Gender non-conformity in science fiction: interrogating gender as language in The First Sister trilogy
Full text linkThis project seeks to analyze gender through the lens of a language within the First Sister Trilogy. The purpose of this approach is to interrogate the multitude of ways in which gender is performed, experienced, and read, in order to create a consistent and coherent framework with which to articulate the fluid and multifaceted nature of gender. More specifically, it seeks to investigate the ways that science fiction, as well as other forms of speculative fiction, may be used in order to improve reader understanding of gender as a construct, making them more able to grasp and articulate the ways in which gender exists as a fluid and nuanced structure