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Exploring Electrophilicity and Noncovalent Interactions Through Molecular Instruments
No full textThis thesis presents the development and application of molecular instruments to quantify weak noncovalent interactions (NCIs) and measure the reactivity of electrophiles. Chapter 1 introduces the advantages of molecular devices over traditional approaches for studying NCIs and deriving empirical parameters, showcasing diverse molecular systems designed to measure NCIs, establish reactivity scales, function as fluorescent sensors, and validate theoretical predictions. Chapter 2 focuses on using a molecular rotor to develop an electrophilicity parameter that predicts the reactivity of electrophiles in key organic reactions, including Michael addition, SN2, SNAr, and cross-coupling oxidative addition reactions. Chapter 3 explores a series of N-phenylimide molecular balances to quantify weak solvophobic interactions in organic solvents, evaluating the influence of polar and nonpolar surfaces and their sizes on interaction strength. Finally, Chapter 4 introduces a new class of N-phenylimide molecular balances designed to investigate London dispersion forces (LDFs) and assess the role of organic solvents in modulating these interactions. Thus, this work provides innovative tools for studying fundamental molecular interactions and reactivity, advancing our understanding of organic reaction mechanisms and noncovalent forces in diverse chemical environments
Educational Technology in Peer-Led Academic Support in Higher Education: the Impact of Technology-Focused Training on Peer Educators’ Session Plans
No full textStudents interact with technology daily; whether that is in the classroom, engaging with classmates, or studying material. Although technology has been widely adopted across the field of higher education, it has not been widely utilized to engage with students through the peer-to-peer support model. The purpose of this action research was to evaluate the implementation of educational technology training and its effect on undergraduate peer educators’ confidence to utilize technology in their plans for their peer-to-peer support sessions at a university in the southeast of the United States of America. The research will address the following research questions: How confident are peer educators in their abilities to utilize educational technologies in their peer-to-peer support sessions? To what degree does the educational technology training impact peer educators’ session plans? What are the peer educators’ perceptions about incorporating educational technologies in their peer-to-peer support sessions?
The participants of this study were 17 peer educators who work at the University’s Student Success Center. The participants took part in a four-week intervention where they learned an overview of educational technology, and experience a more in-depth training on Kahoot, Mentimeter, and Class Collaborate. A convergent parallel mixed methods approach was used through the execution of observations, individual interviews, and session plans. Data was analyzed through inductive analysis and descriptive statistics.
Results from this study demonstrate that technology confidence does not always translate to confidence in utilizing educational technology platforms. Peer educators demonstrated the perception that while educational technology can be helpful, it depends on the course material they are covering. The intervention resulted in the participants demonstrating increased confidence in integrating educational technology in session plans, regardless of the type of material being covered
Investigating the Ecology of the Homeless Court: The Promise of Quasi-Experimental and Statistical Learning Methods
No full textInteractions with the legal system are a crucial factor in maintaining homelessness. Difficulties in addressing legal issues are barriers to accessing services and finding employment and housing. Across the United States, the homeless court is an emerging legal program that has been developed to break this cycle, but they appear to face numerous capacity and coordination problems. Few empirical and systematic investigations have been conducted on homeless court programs. Further, previous studies of homeless courts focus their process and outcome measures on the priorities of the legal system. An investigation into the ecology, or environmental context, of homeless persons would improve our understanding of how such interventions transform the ecology, supporting improvements on the program model. As such, the proposed study aims (a) to investigate the effect of Columbia Homeless Court on its participants across income, living situation, health insurance and disabling conditions (b) test the feasibility of statistical learning methods for investigating the ecology of homeless court participants and non-participants. This quantitative study collected predictors and outcome data from the Homeless Management Information System on both participants of the homeless court program and others served by the Midlands Area Consortium for the Homeless. General linear models were used to compare outcomes between participants and non-participants with the homeless court. For their ease of interpretability and efficiency in identifying linear and non-linear relationships, tree-based statistical learning methods (classification trees, regression trees, and Bayesian additive regression/classification trees) were used to conduct variable selection and understand variable interactions to support theory development relating to the ecology of homeless court participants. Results indicated that (1) the assessment found null effects of the homeless court on the multiple tested outcomes and (2) the centrality of health insurance, age and income as selected variables was noted across all interpretable models. I also provide some recommendations to improve the feasibility of systematic homeless court evaluations and discuss the implications of the statistical learning models and their feasibility in understanding the ecology of homelessness
Reduced Order Model-Based Framework for Microsecond Model Updating of Two-Dimensional Structural Systems Using the Local Eigenvalue Modification Procedure
No full textReal-time model updating is crucial for active structures and electronic assemblies subjected to high-rate dynamic events. High-rate dynamic events refer to events that occur at high speeds and with rapid changes in the forces and energy involved. These events can include explosions, impacts, and crashes. These systems are characterized by a high dynamic response with a high rate (\u3c 100 ms), high amplitude (\u3e 100 gn), highly nonlinear, meaning that the response is not proportional to the applied force, and involve complex interactions between multiple objects or materials. A system exposed to high-rate dynamic environments is frequently prone to rapid plastic deformation, involving violent and destructive effects, such as shockwaves, fragmentation, and deformation of structures, which can cause structural, electrical, and sensor damage. Understanding these characteristics is crucial for predicting and mitigating high-rate dynamic events’ effects and designing materials and structures that can withstand these extreme conditions. Challenges associated with estimating and updating the state of high-rate dynamic events in real-time include (1) adequate sensing,(2) lack of system knowledge, (3) high variability in loads, and (4) limited resources for algorithm implementation. The state estimator must be quick and resilient to the significant uncertainties, non-stationarities, and strong disturbances associated with high-rate dynamic systems.
This work proposes and implements the Local Eigenvalue Modification Procedure (LEMP) as an efficient method for updating real-time structural models to address these challenges. LEMP simplifies the computational process by using a single generalized eigenvalue solution from the system’s baseline state and reducing subsequent computations into a set of second-order secular equations. These equations isolate only the degrees of freedom associated with structural changes, transforming the updating problem into a localized one that avoids re-solving the full eigenvalue problem. A divide-and-conquer algorithm is introduced to solve these secular equations efficiently, achieving state update times well below the 1 ms threshold required for real-time performance. The methodology is validated first on 1D beam structures using the DROPBEAR experimental testbed and later extended to 2D plate models and complex PCBs undergoing damage. Across all tested configurations, LEMP consistently achieved sub-millisecond state update times and high accuracy, with signal-to-noise ratios exceeding 30 dB in most modes and mean absolute errors under 1 Hz for lower modes.
Furthermore, this work advances LEMP’s applicability to reduced-order models (ROMs) and more complex 2D systems. An optimized 25-node cantilever plate configuration was developed and validated as the optimal reduced mesh for capturing local stiffness changes. A single and four-state perturbation was introduced, and the corresponding frequency responses were evaluated. Results show that LEMP maintained less than 10% error compared to full generalized eigenvalue (GE) computations while being 20 to 22 times faster for state changes. For instance, a four-state local stiffness change took only 1.62 ms to compute using LEMP versus 36.04 ms with GE, confirming its real-time viability. These contributions are supported by robust parametric studies involving mode selection, nodal reduction, and error profiling, all of which informed the development of a practical, deployable framework for high-rate environments.
This work advances the field of structural health monitoring by delivering a computationally efficient, accurate, and scalable model updating strategy capable of tracking high-rate structural dynamics in real-time. Modal reduction, algorithmic optimization, and application-specific modeling offer a powerful tool for adaptive system control, especially in mission-critical domains. Through the LEMP framework, this dissertation lays the foundation for smarter, faster, and more resilient structural monitoring and response systems under extreme dynamic conditions
The Dialogic Self: Persius Satires 4 and Oikeiosis in Stoic Philosophy
No full textThough acknowledging that Persius alludes to Horace so frequently that he creates a dialogue with his elder, many commentators fail to see that Persius would challenge his predecessor. Especially evident in Satire 4, Persius\u27 challenge to Horace stems from the younger poet\u27s Stoicism, which philosophy he sees Horace as lampooning throughout the elder poet\u27s Satires. Persius not only defends his Stoicism in Satires 4 but also engages with perceived weaknesses in the Epicureanism he finds in Horace. For instance, instead of the Epicurean version of natural law Persius finds in Horace, which conceives of human ties as contractual, the younger poet would offer oikeiosis, which posits that humans are innately disposed to bond together
Inorganic Nanoparticle and Nanoplastic Transformations and the Impact on Biouptake by Freshwater Algal Cells Using Single Cell and Single Particle Inductively Coupled Plasma Mass Spectrometry
No full textThe ubiquitous presence of nanoparticles (NPs) and nanoplastics (NPPs) and their effects on environmental and human health is a significant concern. They are used in every aspect of our lives, and while they offer many benefits, there are concerns about their impacts on ecosystems and human health. The primary aim of this dissertation is to quantify NP and NPP transformations in the presence of algae and determine how those transformations influence bioavailability. The methodology involves two complementary analytical techniques: single particle (SP) and single cell (SC) inductively coupled plasma mass spectrometry (ICP-MS). These techniques are tested and applied to two freshwater microalgal cell types after exposing them to inorganic NPs, including gold (Au), silver-shelled gold (Au@Ag), and palladium NPPs. Post-exposure, cells were separated from the cell suspension to remove dispersed NPs and NPPs that were not cell-associated. Cell-associated NPs and NPPs were then measured by SC-ICP-MS and the dispersed NPs and NPPs removed during the wash steps were quantified using SP-ICP-MS. Experiments showed that 80% of cells are lost during the sample preparation. Due to the loss of cells during cell suspension preparation, cells must be grown to a concentration of approximately 400,000 cells mL-1 to ensure enough cells remain for SC-ICP-MS. Each cell type must be optimized before analysis by SC-ICP-MS. It was found that NPs and NPPs are cell-associated post-exposure, and individual cells will typically have at least one cell-associated NP (Au and Au@Ag). Cell exposure to varying concentrations of Au and Au@Ag nanoparticles for the same duration did not result in an increased number of cell-associated nanoparticles at higher concentrations. However, when exposing cells to Au and Au@Ag NPs for a longer duration (e.g., 72 hours versus 48 hours), cells showed an increase in cell-associated NPs. When exposing the same cells to Pd@PAN NPPs, it was found that NPPs agglomerate both in the cell suspension and when cell-associated, with each cell having at least one agglomerate consisting of 300 Pd NPPs. Single particle and single cell ICP-MS provide a means for understanding NP and NPP transformations in complex media at environmentally relevant concentrations and how those transformations result in their biouptake. This can yield important information on the ecological and human impact of exposure. The methods described in this dissertation can be applied to a wide range of cell types to provide quantitative data on how nano-sized materials transform and are taken up on a cell-by-cell basis
Strain and Redox Engineering for Enhanced Thermoelectric Performance in Transition Metal Oxide Thin Films
No full textThe discovery of highly efficient and cost-effective thermoelectric (TE) materials is essential to envision high-performance TE power generators that enable the direct conversion of waste heat into electricity. Transition metal oxides (TMOs) are considered promising candidates for high-temperature TE applications due to their excellent thermal stability and low cost. However, their maximum power output (power factor, PF = σ•S2) is constrained by the intrinsic trade-off between thermopower (S) and electrical conductivity (σ), both of which are inversely related to carrier concentration. This trade-off poses a significant barrier to improving the performance of TE devices. Among various strategies to overcome this limitation, this study focuses on two emerging strategies: 1. strain engineering and 2. redox engineering, utilizing epitaxial thin films synthesized pulsed laser deposition (PLD) as a model system.
Epitaxial strain is a powerful approach for controlling the physical properties of materials. While it has demonstrated potential for tuning the TE properties of oxides, the underlying mechanisms are not yet fully understood. To investigate the impact of strain on TE properties, epitaxial SrRuO3 (SRO) thin films were grown on three different single crystal substrates: LaAlO3, (LaAlO3)0.29(SrAl0.5Ta0.5O3)0.71, and SrTiO3, which induce complete relaxation, -0.53% compressive strain, and -1.47 % compressive strain, respectively. The PF of SRO increased with increasing compressive strain. In-situ X-ray diffraction and TE property analysis revealed that compressive strain reduces the concentration of oxygen vacancies while maintaining carrier concentration. As a result, electrical conductivity increases due to enhanced carrier mobility, while thermopower remains unchanged, leading to an improvement in PF.
Nanoinclusion strategies, such as embedding metallic particles in a TE material, are also known to effectively tune TE properties. However, maintaining the stability and integrity of metal nanoparticles within an oxide matrix is inherently challenging. To overcome these limitations, this work exploits metal exsolution—a process that arises from the unique redox flexibility and defect chemistry of TMOs, wherein nanoparticles emerge from the oxide matrix under reducing conditions. Two different material systems: La0.7Ca0.2Ni0.25Ti0.75O3 (LCNTO) and Sr0.95Ti0.76Nb0.19Ni0.05O3 (STNNO) were used to investigate the influence of exsolved metal particles on the TE properties of TMOs. In LCNTO, the exsolved Ni particles after reduction significantly enhanced the PF by increasing both S and σ. The enhancement in S was attributed to energy-dependent electron scattering at the interfaces, while the conducting network formed by metal particles accounted for the increased σ. Similarly, STNNO thin films exhibited a significant increase in PF due to exsolved Ni particles; however, in this case, the improvement was attributed solely to the enhanced σ, without an energy filtering effect.
Building on these findings, a simplified, one-step exsolution process was developed by tuning the PLD growth conditions. By reducing the oxygen partial pressure (\u3c 0.3 mTorr), spontaneous exsolution of Ni nanoparticles was achieved during film growth, yielding a PF improvement of approximately seven orders of magnitude.
These results demonstrate that the combination of strain and redox engineering provides a robust and scalable framework for enhancing the thermoelectric performance of TMOs. Together, these strategies address long-standing limitations in oxide TE materials and open new pathways for the development of efficient, high-temperature TE applications
Hearing All the Colors: Stories of Engagement from Teachers\u27 Perspectives
No full textThis qualitative case study documented four high school English II End of Course teachers\u27 stories about student engagement in the classroom. Students of color, in particular, have been maligned for underperformance on state-mandated tests. Instead of focusing on the despairing headlines and data, this study focused on how teachers follow the state standards and district curriculum guides to increase success. The teachers\u27 authentic voices on student engagement shine through their stories. Student engagement is not a one-size-fits-all scenario which these teachers prove.
The teachers\u27 stories served as the data for this study. The data was viewed through the lens of Culturally Relevant Pedagogy(Ladson-Billings, 1995) and Funds of Knowledge (Gonzalez, et al., 2005). When teachers consider students’ cultural backgrounds, knowledge from home, and community, learning becomes an outreach that bridges home and school. Ladson-Billings (1995) says “that’s just good teaching!”(p. 159). Moreover, through these stories, a teacher community was formed. A safe place to be heard and to share ideas
Conjuring Realities: Southern Supernaturalism and Race from the Antebellum Era to the Early Twentieth Century
No full textConjure practices in the nineteenth-century American South, such as “Hoodoo” or “Voodoo,” are commonly portrayed as primarily “black” beliefs or entrenched in “Africanistic” cultures. For the enslaved, their black spiritual systems, including conjure, were a powerful tool of resistance against the white enslaver. Black conjure practitioners established themselves as an affordable and pervasive medical alternative to often ineffective or harmful professional medicines for black and white Southerners, regardless of class. In this way, conjure challenged the authority of racial capitalism and destabilized the perceived moral and intellectual superiority of whiteness. Moreover, by examining legal documents, newspapers, fictional literature, and oral accounts, this thesis argues that conjure, while rooted in Afro-Atlantic contexts, was not solely a black practice. Rather, conjure was the cultural and spiritual product of an interracial and interconnected Southern society, one that transcended the rigid lines of racial division and violence from the antebellum period to the dawn of Jim Crow. White, black, and indigenous people in the South accepted, used, and paid for the services of conjurers regardless of racial or class identity. Nonetheless, conjure medicine and belief, ultimately, remained portrayed as inferior and immoral when compared to systems deemed as “legitimate,” “scientific,” or, in effect, culturally “white.” Despite this dominant perception, conjure practice persisted and, through its medical and economic interconnectivity, went against the grain of racial capitalism
Combining Remote Sensing and Field Sampling to Assess Microphytobenthos Distribution in the North Inlet Estuary, South Carolina
No full textThe study of microphytobenthos (MPB) distributions in mudflat ecosystems is critical for understanding coastal ecosystem health and resilience. This research integrates high-resolution multispectral imagery and elevation data to predict chlorophyll-a concentrations in mudflats within the North Inlet estuary, South Carolina. Using statistical analyses, MSAVI was identified as the most effective spectral index for chlorophyll-a prediction, and a regression model was generated for this index, finding significant correlation with elevation. Temporal and spatial patterns of chlorophyll-a distributions were explored through predictive rasters, revealing significant relationships between MPB abundance and microtopography. These findings demonstrate the value of remote sensing for non-invasive MPB monitoring and provide a foundation for advancing coastal management practices, particularly in tracking ecosystem responses to environmental stressors