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Atomic Layer Deposition for Efficient, Stable, and Scalable Perovskite Solar Cells
No full textSolar energy has emerged as a promising renewable energy source, drawing significant attention worldwide. Among various photovoltaic materials, perovskite (PVK) stands out as one of the most promising candidates for solar energy harvesting. My research focuses on optimizing high-performance perovskite solar cells (PSCs) by addressing key challenges to industrialization through innovative material design and process engineering. My key contributions are as follows: 1. Hole Transport Layer (HTL) Innovation: I developed a dual-oxidant atomic layer deposition (ALD) technique using ozone and water to fabricate high-quality films. This approach enables high reaction rates and controlled surface hydroxylation, resulting in PSCs that achieve 21.2% efficiency and maintain 80% of their initial performance after 500 hours of continuous light soaking. 2. Blade Coating and Additive Engineering in Ambient Conditions: I optimized the blade coating process and vacuum-assisted quenching under ambient conditions. Additionally, the introduction of as a chloride-based additive significantly reduced trap-state density and extended carrier lifetime. This enabled the fabrication of PSCs with 23.9% efficiency and mini modules reaching 18.0%. By integrating synergistic ALD processing, blade coating techniques and chloride additive incorporation, this work significantly improves both the efficiency and operational stability of PSCs. These results lay a strong foundation for the scalable, low-cost manufacturing of high-performance perovskite photovoltaics.</p
Reasons for Asking: Beyond Journey's End
No full textAs rational agents, we hold ourselves to the standard that reasons justify our beliefs and actions. In a similar vein, the act of asking—how we open inquiry—is also justified by reasons. This dissertation presents a systematic approach to understanding how the different components of inquiry function as reasons for asking. By doing so, it aims to clarify key concepts within the philosophy of inquiry, focusing particularly on the role of inquiring attitudes and questions in shaping the nature and direction of inquiry.The central argument is that reasons for asking are bi-faceted, consisting of both the inquiring attitude and the question, which together drive the inquiry process. Drawing an analogy from Frege’s distinction between content and force, this dissertation proposes that while these facets may be metaphysically distinct, as they operate in unison within inquiry, they offer a comprehensive understanding of what it means to rationally inquire.</p
Stress, Racism, and Resilience: The Role of Racism-Related Stress and Coping on Cardiovascular Functioning of Young Black Women
No full textCardiovascular disease (CVD) is the leading cause of death in the United States, with persistent racial–ethnic disparities disproportionately burdening Black communities. This cross-sectional study examined the relationships between general stress, racism-related stress, coping, and cardiovascular functioning in a sample of 38 Black emerging adult women (ages 18-29), a period before the typical onset of clinical CVD. Participants completed measures of perceived stress, racism-related stress, and coping. Cardiovascular functioning was assessed via estimated cardiorespiratory fitness (VO₂ max) and carotid-femoral pulse wave velocity (cfPWV), a gold-standard measure of arterial stiffness. Results indicated that participants exhibited superior vascular health, with cfPWV values significantly lower than the U.S. and worldwide age-specific means. Participants reported moderate general stress, primarily from feeling “Pushed,” and indicated that their most frequent and stressful racism-related experiences were collective and vicarious. Spirituality was the most endorsed coping strategy, whereas Disengagement was the least used. Regression analyses revealed no significant direct relationships between psychosocial stressors and cardiovascular functioning. This null finding, interpreted through a life-course perspective, suggests that the physiological wear and tear of chronic stress is not yet detectable in this young, resilient cohort and provides a critical empirical baseline consistent with models such as the Weathering Hypothesis. The substantial proportion of variance explained in some models (R² = .21 for arterial stiffness) alongside an ambiguous finding for Interconnectedness coping indicates underlying complex, likely indirect pathways. Future research requires longitudinal designs and larger samples to test sophisticated models, as well as the inclusion of Black men to elucidate how psychosocial stressors translate into the cardiovascular health inequities observed later in life
Understanding and Extending the N-Degron
No full textProteostasis – the balance of protein synthesis, folding, and degradation – integrates with stress signaling, metabolism, and cell death. Central to this network is the Arg/N-degron pathway and its defining enzyme, arginyltransferase 1 (ATE1). This dissertation explores ATE1 and the N-degron pathway as both evolutionarily conserved, mechanistic regulators in eukaryotic biology and as possible translational tools.First, I show that ATE1 regulates HIF1α stability in a hydroxylation-dependent manner, contributing to our lab’s work in establishing arginylation as a parallel axis to canonical VHL-mediated hypoxia sensing. Second, I identify a redox-sensitive [Fe-S] cluster in ATE1 that is required for its activity and demonstrate that both [Fe-S] cluster and heme biosynthetic pathways are necessary for ATE1-induced cell death in yeast. Third, I reveal that this cell death occurs independently of ATE1’s canonical role in ubiquitin-mediated degradation, instead pointing to a mitochondria-dependent mechanism that may involve ATP synthase subunit c and the mitochondria permeability transition pore. Finally, I extend N-degron logic into applied contexts, developing proof-of-principle strategies for targeted protein degradation: a type II N-degron PROTAC and a cleavage-resistant ubiquitin fusion, each capable of reducing levels of the oncogenic protein MCL1 in preliminary studies.Together, these findings elaborate on the N-degron pathway, and more specifically ATE1, as a redox-sensitive mediator situated at the intersection of proteostasis, mitochondrial biology, and cell fate, while also demonstrating how its underlying principles can inspire next-generation protein degradation technologies
Understanding Preschoolers' Emotion Regulation and Task Engagement: The Role of High-Quality Teacher Instructional Support Practices
No full textChildren’s ability to engage positively with tasks or learning activities in the preschool classroom is a key indicator of their school readiness. Regulation-related skills, such as emotion regulation, provide a foundation for children to get the most of a learning environment and are associated with positive academic engagement. Notably, children growing up in poverty are at an increased risk for lower self-regulation and have more to gain from high-quality early childhood education programs, in which teachers’ use of high-quality instructional practices may act as a protective factor. In a secondary analysis of two cohorts of preschoolers (N = 480) from 71 Head Start classrooms, the current study used a multilevel analytic approach to examine child-level emotion regulation and lability as contributors to children’s observed task engagement, as well as the direct and moderating role of classroom-level instructional support quality. Findings highlight both emotional lability (i.e., dysregulation) and instructional support quality as significant predictors of children’s gains in task engagement from fall to spring of the preschool year. Sensitivity analyses are included. Implications for future research, practice, and policy in the early childhood education context are discussed.</p
Greenwashing by Meat and Dairy Companies
No full textAnimal agriculture has disproportionate environmental impacts relative to other food production, and animal agriculture alone accounts for at least 16.5% of all global greenhouse gas (GHG) emissions. Many of the largest meat and dairy companies are aware of environmental concerns and make explicit environmental statements and commitments. Here, we evaluated the most recent sustainability reports and websites (2021–2024) of 33 of the world’s largest meat and dairy companies. We identified 1,240 environmental claims, 70% of which (862) were climate related. Companies provided peer-reviewed scientific evidence to support only three of the 1,240 environmental claims, two of which were climate related. Instead, 98% (1,219 claims) had content suggestive of greenwashing. “Empty claims,” defined as claims that either exaggerate achievements or have limited prospects for achieving articulated goals, were the most prevalent. While all 33 companies engage in some form of greenwashing, Danone made the greatest number of claims demonstrating greenwashing, 105 claims (9%) of 1,219 in total. Fifty claims (4%) directly related to possible financial benefits to the company that encourage the industry to maintain business-as-usual or expand them. Companies making the most greenwashing claims were not necessarily the highest emitters. Unchecked greenwashing misleads consumers and investors and further delays the fundamental changes in high-emitting industries necessary to limit global warming.</p
A Qualitative Study Exploring the Role of Culture on Endometrial Cancer in the Haitian Community
No full textIntroduction:Significant racial disparities persist in cancer outcomes, particularly among Black women, who have lower 5-year survival rates for diseases such as endometrial cancer (EC). Delays in detection contribute to more advanced-stage diagnoses and poorer prognoses, yet little is known about the specific cultural and structural factors influencing these delays among Haitian women. Existing studies often overlook how cultural beliefs, family dynamics, healthcare mistrust, and limited awareness of EC symptoms, such as abnormal vaginal bleeding, shape healthcare-seeking behaviors. This study explores how cultural factors influence healthcare-seeking among Creole-speaking Haitian women.Methods:We conducted four focus groups with 19 Haitian women under 50 years old. Data were analyzed using a Thematic Analysis (TA) codebook approach, structured around the Andersen Model of Total Patient Delay. Two independent raters coded the transcripts using NVivo qualitative software.Results:Six major themes emerged: Awareness and Understanding of Menopause, Information Seeking and Appraisal, Social Influence on Decisions, Stigma and Taboos, Access and Organization, and Traditional Practices and Beliefs. Participants exhibited limited awareness of EC, often attributing abnormal bleeding to non-cancerous causes like hormonal imbalances or contraceptive use. Cultural beliefs, family influence, reliance on traditional remedies, and spiritual practices contributed to healthcare delays. Barriers included financial constraints, long appointment wait times, and mistrust in healthcare providers. Participants preferred culturally tailored education and community-based resources for health information.Conclusions:Culturally sensitive interventions are essential to improve EC awareness, build healthcare trust, and reduce systemic barriers. Addressing traditional practices, family dynamics, and spiritual beliefs is key to promoting early detection and improving cancer outcomes among Haitian women
Mechanisms by Which Low-Dose IL-2/CD25 Fusion Protein Limits Diabetes in NOD Mice
No full textSuppression of autoreactive T cells by regulatory T cells (Tregs) is essential for immune tolerance and homeostasis. Interleukin-2 (IL-2) is critical for Treg development, function, and maintenance. Tregs constitutively express the high-affinity IL-2 receptor (IL-2R), enabling them to respond to much lower IL-2 levels compared to T effector (Teff) cells. Many autoimmune and inflammatory diseases exhibit quantitative and qualitative defects in Tregs and IL-2/IL-2R signaling. Clinical trials in autoimmune patients receiving low-dose (LD) recombinant (r) IL-2 have shown increases in Tregs and improvement in clinical outcomes. However, achieving robust control of autoimmunity is unlikely due to poor pharmacodynamics of rIL-2 which cannot sustain a constant elevation of highly functional Tregs. Here we utilize the NOD mouse model of type 1 diabetes and a novel, long-lasting IL-2-based biologic, where mouse IL-2 is covalently linked to mouse IL-2R CD25 subunit, to investigate the cellular mechanisms underlying the tolerance-enhancing effects of LD IL-2. By varying the administration of IL-2/CD25 fusion protein, we show that a sustained, but not a periodic increase in Tregs is highly effective in inhibiting autoimmunity. Analyses of pancreatic islets using flow cytometry and single-cell RNA sequencing revealed that IL-2/CD25 rapidly changes the islet immune microenvironment. IL-2/CD25 induces a marked increase in activated effector (e) Tregs, particularly ST2+ eTregs, type 2 innate lymphoid cells (ILC2s), and cytokine-producing regulatory natural killer (NK) cells, while islet antigen-reactive CD4+ and CD8+ T cells decrease. T cell receptor repertoire analysis revealed a reduction in multiple dominant clonotypes associated with effector CD4+ and CD8+ T cells. These effects were amplified upon extended treatment with IL-2/CD25. Thus, sustained suppression of self-reactive CD4+ and CD8+ Teff cells and robust control of autoimmunity requires a constant elevation of Tregs and suggests a potential beneficial role for ILC2s and cytokine-producing NK cells. </p
Examining the Impact of Adverse Life Events and Mental Health on Cardiovascular Disease Risk among Black Women Living with HIV: Does Resilience Mitigate CVD Risk?
No full textBlack women living with HIV (BWLWH) are particularly vulnerable for experiencing worsened cardiovascular health. Trauma exposure and intersectional stigma are common sources of stress among BWLWH and have been directly linked to adverse mental health outcomes which often heightens CVD risk. To manage stress related to sexism, racism, and HIV stigma, Black women often rely on resilient coping mechanisms which may include intrapersonal resilience, social support, and posttraumatic growth. However, little is known about how this myriad of psychosocial factors together may influence CVD risk among BWLWH. The present study evaluated whether intersectional adversities including HIV discrimination and microaggressions, racial discrimination, gender discrimination, gendered racial microaggressions, and trauma exposure predict CVD risk via depression and trauma symptoms among 117 BWLWH through utilizing structural equation modeling and path analysis. Resilience resources was also explored as a moderator. Latent microaggressions and latent trauma exposure had significant direct and positive relationships with traumatic stress symptoms and depression symptoms. There were also significant direct pathways from intersectional adversities to traumatic stress symptoms and depression symptoms. Latent resilience resources moderated the relationship between intersectional adversities and traumatic stress symptoms. Indirect and direct pathways to CVD risk were not significant in each model. Trauma exposure and discrimination at the intersection of race, gender, and HIV status have a negative impact on the mental health of BWLWH. Resilience resources may help mitigate some of the negative consequences such stressors and adversities can have on their mental health. Given the prevalence of CVD risk factors among BWLWH more research is needed to elucidate the psychosocial mechanisms that contribute to racial and gender disparities in cardiovascular health among this population over time.</p
Privacy-Preserving Algorithms for Inventory Control
No full textIn the era of data-driven decision-making, feature-based inventory analysis has emerged as a powerful approach for enhancing operational efficiency by leveraging contextual data. However, the growing concerns over data privacy—especially with sensitive customer information—pose significant challenges to the practical deployment of such methods. This dissertation addresses this critical gap by developing a comprehensive framework for privacy-preserving inventory control under differential privacy (DP) constraints.The dissertation comprises two main projects and one minor project. The first project focuses on the offline setting, where a differentially private algorithm is developed to solve the classical newsvendor problem. The proposed method utilizes smoothed empirical risk minimization and clipped noisy gradient descent within the Gaussian differential privacy (GDP) framework. The algorithm not only guarantees rigorous privacy protection but also achieves favorable statistical performance with provably low excess risk. The second project investigates the online setting, where data arrive sequentially and decisions must be made in real time. A novel differentially private stochastic sub-gradient method is proposed to address two fundamental challenges: censored demand and non-perishable inventory. The algorithm is designed to satisfy a strengthened form of local differential privacy (LDP). Despite the complexity introduced by data dependence and partial observability, the algorithm attains a sublinear regret bound. Overall, this work contributes to the fields of operations management and privacy-preserving machine learning by bridging theoretical rigor and practical relevance. It demonstrates that effective and privacy-compliant inventory control is achievable in both static and dynamic environments, paving the way for secure data utilization in modern supply chains. My dissertation also includes a minor project related to policy evaluation in reinforcement learning (RL).</p