Institutional Repository

The UDSpace Institutional Repository collects and disseminates research material from the University of Delaware.

  • Faculty, staff, and graduate students can deposit their research material directly into UDSpace. Faculty may use UDSpace to fulfill the University of Delaware Faculty Senate Open Access Resolution, and in many cases may use it to fulfill open access requirements from grant funding agencies.
  • Departments can use UDSpace to publish or distribute their working papers, technical reports, or other research material.
  • UDSpace also includes all doctoral dissertations from winter 2014 forward, and all master's theses from fall 2009 forward.

To learn more about UDSpace, and how you can make your research openly accessible to the public, visit our UDSpace Policies website.

 

Recent Submissions

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Synthetic efforts toward the total synthesis of premnalatifolin A & monomeric unnatural icetexane analogs
(University of Delaware, 2022) Amiri Naeini, Ali
Icetexanes are a family of natural products with a wide array of biological activities and complex structure, which has encouraged synthesis chemists to approach them with different strategies over the past decade. Chapter 1 outlines the different types of icetexanes and then takes a closer look at the newly discovered icetexanes—since 2009—and their biological activities. Chapter 1 is then concluded with a discussion around the last decade of development on the synthesis of icetexane natural products and their core structure. ☐ Chapter 2 outlines the prior and current effort on synthesis of icetexanes and their core 6–7–6 structures. Inspired by the remarkable works of Mr. Daniel J. Moon and Dr. Mohammad Al–Amin in the Chain Laboratory, chapter 2 is focused on development of a small library of inverted icetexanes. During this chapter the capability of the Richie formylation in generating para methoxy benzaldehydes as well as a new tandem formylation–cyclization reaction to synthesize both dihydrobenzofurans and dihydrobenzopyrans was demonstrated. ☐ Chapter 3 focuses on the synthesis of conventional unnatural icetexane analogs. Additionally, chapter 3 outlines the path toward completion of premnalatifolin A’s monomers and in due course, the natural product premnalatifolin A itself.
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Non-ideal solutions for biomass upgrading
(University of Delaware, 2022) Rodriguez Quiroz, Natalia
The growing demand for fossil fuels and increasing concerns about the environmental impact of their production and utilization have driven research to explore alternative renewable feedstocks and develop green and efficient technologies for their upgrade to fuels and chemicals. Nonedible lignocellulosic biomass is a promising carbon source owing to its abundance and high chemical functionality. Despite extensive investigation in the field of biomass valorization, critical challenges remain. Homogeneous catalytic systems offer solutions to many of these challenges. Nevertheless, the complex behavior that makes them promising also makes them difficult to understand, hindering advancements towards industrially feasible processes. This thesis aims to provide a fundamental understanding of the molecular interactions governing the reactivity of promising non-ideal aqueous (chapters two and three), biphasic (chapter four), and organic (chapter five) systems capable of alleviating bottlenecks in biomass valorization. ☐ First, we investigate homogeneous metal salt solutions as promising media in lignocellulose upgrading. We find that the role of the metal salts changes from dilute to concentrated solutions to molten salt hydrates (MSH). Dilute solutions of transition metal halide salts exhibit catalytic properties governed by metal-water speciation. The speciation is a secondary effect in more concentrated solutions, where the molecular interactions between the solvent, organic substrates, and salts become essential. These complex interactions change the activity coefficient of the species, evidenced by changes in the solubility of the sugars. These effects are further enhanced in MSH, where the substrate-salt interactions dominate and determine the ability to dissolve and hydrolyze cellulose in solution. ☐ We elaborate on the promising capabilities of MSH in chapter three. Specifically, we study the hydrolysis of cellulose in LiBr AMSH, attaining high glucose yields at low acid concentrations, low temperatures, and short times with potentially considerable economic benefits. Enabled by thermodynamic modeling and detailed kinetic studies, we find that the enhanced hydrolysis of cellulose in LiBr AMSH stems from a salt-induced increase in acidity due to preferential solvation of the salt's cations which draws solvation away from the acid catalyst, increasing the activity. Overall, we reveal that the efficacy of MSHs to hydrolyze cellulose is mainly determined by the effect of the salt on the solution's acidity. ☐ In Chapter 4, we couple fast experimental reaction kinetics, spectroscopy, and multiscale modeling to elucidate the enhancements in the rate and selectivity of fructose dehydration in biphasic systems. We show that apparent insoluble solvents used in biphasic systems can reach significant mutual solubility with water at reaction temperatures, enabling the partition of the sugar and catalyst into the extracting phase. In the organic-rich environment, the dehydration of fructose proceeds faster and more selectively than in water due to increased relative abundance of the reactive furanose isomer, enhanced water-catalyst-substrate interactions driven by nanophase separation, and higher product stability stemming from preferential solvation. We demonstrate that these solvent effects impact other critical biphasic reactions in biomass upgrading and provide qualitative principles for solvent selection. ☐ Finally, Chapter 5 exploits non-polar-organic-rich solvent systems formed upon partitioning the aqueous to the organic phase for the thermodynamically unfavorable Brønsted acid-catalyzed glucose dehydration. In saturated MIBK/water systems, we achieve unprecedented yields of HMF from glucose, catalyzed solely by hydrochloric acid. We reveal that in ketone solvents, glucose undergoes dehydration via an acyclic isomerization to fructose initiated by protonation of the ring oxygen enabled by solvent enhanced catalyst-ring oxygen interactions. Ultimately, we expose the pivotal role of solvents in overcoming glucose’s low reactivity and selectivity by guiding selective protonation of the glucose site leading to HMF formation.
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Trauma focused interventions: caring for adults with comorbid trauma and substance use disorders
(University of Delaware, 2022) Okemwa, Leonidah
Background/Purpose: Mortality related to substance overdose in the U.S. affects young and old individuals with trauma history playing a key role in determining health outcomes. Substance overdose deaths may be preventable if the underlying emotional trauma is diagnosed and treated appropriately. The aim of this project was to promote trauma care through staff education and evaluate its impact on abstinence and treatment adherence rates in adults with substance use disorder. Methods: Staff at the local substance use disorder treatment facility received a one-hour in-person training on SAMHSA developed six principles of trauma-informed care. Staff then implemented trauma-informed care practices for twelve weeks. A de-identified chart review was completed to collect data on abstinence and treatment adherence rates over a twelve-week period. This was compared to the pre-implementation data collected on the same patients and variables with a look-back period of one year. Results: Over a period of 12-weeks, 50 charts were reviewed, out of which, 38 patients (76%) showed abstinence, while 10 (20%) were re-admitted to the inpatient setting. Using two-tailed t-test, statistically significant improvement in post-intervention abstinence and treatment adherence rates was established. Conclusion & Implications: This nurse-led project promoted adoption of evidence-based care that improved patient outcomes related to abstinence and treatment adherence. This project has the potential for positive contribution to the implementation of trauma-informed care in patients with substance use disorder.
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The urban tree canopy's understory: an analysis of the green view index in Wilmington, Delaware
(University of Delaware, 2022) Seo, Samuel
Cities in the U.S. are growing and continue to lose tree canopy every year. City managers, already struggling to keep up with deferred infrastructure maintenance costs, must justify tree conservation and planting initiatives to a diverse range of stakeholders. Public-private partnerships provide the means to plan and fund projects collectively, but challenge traditional modes of understanding the benefits of trees. In this context, while tree inventories and structural measurement methods facilitate basic maintenance of the urban forest, a street view imagery-based analysis known as the Green View Index(GVI) can serve as a measure of the interactions that take place below the urban canopy. And by leveraging the use of machine learning to efficiently assess trees over wide geographic extents, municipalities can develop novel approaches to monitoring and maintaining their trees. This analysis demonstrates how GVI differs from inventory and remote sensing data and suggests its utility in formulating alternative urban forest policy.
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Examining provider participation in the child care subsidy system: a mixed methods study
(University of Delaware, 2022) Slicker, Gerilyn
Early care and education is not affordable for most U.S. families. The Child Care and Development Fund is a federal program that aims to help families from low-income backgrounds access more affordable care through child care subsidies which offset the cost of care. However, the number of child care providers that accept subsidies is declining, threatening families’ access. This dissertation project is a three-phase mixed methods study aimed at understanding how early care and education centers make decisions about subsidy system participation, paying close attention to the influence of state policies and other factors amenable to policy intervention. Phase I is a mixed methods statewide study that examines how providers make decisions about accepting subsidies. In phase II, nationally representative data is used to examine predictors of subsidy density, or the proportion of children in a program using subsidies. Phase III uses a nationally representative sample of early care and education centers alongside state-specific subsidy policies to examine the unique influence of subsidy policies on provider participation in the subsidy system. This dissertation provides useful insights into how to implement state policies and practices that could incentivize providers’ participation in the subsidy system, and as a result better serve families from low-income backgrounds.