Doctor of Philosophy (PhD), Ohio University, 2017, Chemical Engineering (Engineering and Technology)

Ammonia is a crucial chemical used in many fields such as the fertilizer, textile, and food industries. Nowadays, ammonia is commonly used as a reducing agent to reduce nitrogen oxide (NOx) to non-harmful nitrogen gas and water which is called the selective catalytic reduction (SCR) process. For the on-site production of ammonia, two traditional methods are urea hydrolysis and urea pyrolysis. However both of them require high temperature and pressure which are not accessible in mobile engines. A novel electrochemically induced urea to ammonia (eU2A) process in alkaline media was introduced and investigated in this investigation. Nickel beads are employed as the working catalyst in a two-electrode eU2A reactor using 7.0 M KOH as the supporting electrolyte at 70 °C. The ammonia generation rate per effective volume of catalyst in the eU2A process is ~28 times higher than the thermal hydrolysis of urea (THU). The eU2A operates at low temperature and pressure which is suitable for SCR process in mobile engines and saves energy. The eU2A process is a promising technique that finds applications on the SCR process for the removal of nitride oxide from combustion systems (e.g., diesel vehicles and power plants). In addition, the mechanism of eU2A in the alkaline medium using nickel electrodes was investigated in a classical three-electrode reactor with a mercury/mercury oxide reference electrode. In this investigation, the intermediates and products in the bulk solution were monitored by Fourier Transform Infrared spectroscopy, and the intermediates and products on the catalyst surface in eU2A process were analyzed by in-situ Raman spectroscopy. Urea electrolysis and THU (in the bulk solution) take place in parallel with the eU2A process in the eU2A reactor. It was found that the ammonia production rate depends strongly on the amount of nickel oxyhydroxide and the concentration of OH- ions. In addition, the redox couple of Ni2+ and Ni3+ ions played important roles in ammo (open full item for complete abstract)

Committee: Gerardine Botte (Advisor); Howard Dewald (Committee Member); David Ingram (Committee Member); Kevin Crist (Committee Member); John Staser (Committee Member) Subjects: Chemical Engineering

Master of Science, The Ohio State University, 2014, Chemistry

Development of a new enhanced boronate urea that benefits from internal coordination of the urea carbonyl to a strategically placed Lewis acid has enabled a new direction in hydrogen bond donor (HBD) catalysis. Activation of a-nitrodiazocarbonyl compounds has elicited carbene-like reactivity, allowing for access to metal-free insertion reactions. Recent developments have utilized the difluroboronate urea with an organic acid cocatalytically to promote insertion reaction with aryldiazoacetates. These reactions are proposed to occur through a HBD induced heteroatom acidity amplification, facilitating protonation of the a-aryldiazoacetates, which can undergo a nucleophilic attack by the conjugate base. Understanding of the insertion mechanism has led to asymmetric cocatalytic variations of the insertion reactions utilizing both chiral acids with achiral HBD catalyst and chiral HBD catalyst with an achiral acid. Work towards an asymmetric reaction has illuminated the one lacking feature of the boronate catalyst: its ability to achieve enantioselectivity, which has been an ongoing problem to advancements with these catalysts. Herein, development of a new chiral catalyst design and a new metal-free approach to a selective insertion reaction are discussed.

Committee: Anita Mattson (Advisor); Claudia Turro (Committee Member) Subjects: Chemistry; Organic Chemistry

Doctor of Philosophy, The Ohio State University, 2014, Chemistry

Strategic enhancement of urea organocatalysts using internally coordinated Lewis acids has allowed for the discovery of new and useful reactions. Specifically, the incorporation of transition metals onto urea scaffolds has been shown to improve catalytic activity when compared to traditional urea and thiourea catalysts. An example of this enhancement has been demonstrated in the development of hybrid urea palladacycles that have been shown to be highly active, hydrogen bond donor catalysts in the activation of substrates not amenable to traditional urea catalysis, such as alkylidene malonates. Other internal Lewis acids such as platinum, silicon and boron have also been incorporated onto urea scaffolds, and the new catalysts have been compared in their abilities to activate new substrates such as nitrocyclopropane carboxylates and nitrodiazoesters. Correlations between catalyst structure and activity show that increased acidity due to internally coordinated Lewis acids is one of the important factors in urea catalyst design. To compare the internal Lewis acids' effects on acidity and on catalyst activity, the pKas of differently internally-coordinated catalysts have been determined and found to range from a highly acidic 6.8 for a coordinated palladium to a weakly acidic 16.0 for a silicate urea. Boronate ureas surveyed had intermediate pKas of 7.5 and 9.5. The different catalysts' abilities to activate both nitrocyclopropanes and nitrodiazoesters by coordination to the nitro group have also been investigated by studying the rates of these reactions. An internally coordinated difluoroboronate urea has been determined to be the best catalyst for both reaction systems. Using urea catalysts, a new organocatalytic coupling strategy has also been discovered. Specifically, nitroamines and nitrimines have been identified as urea-activated handles allowing for useful carbon–heteroatom and carbon–carbon coupling reactions. This reaction mode has been shown to (open full item for complete abstract)

Committee: Anita Mattson (Advisor) Subjects: Chemistry; Organic Chemistry

Master of Science, The Ohio State University, 1975, Animal Science

Committee: L. Swiger (Advisor) Subjects:

Master of Science, Miami University, 2011, Zoology

Facilitative urea transporters (UT) are potentially involved in urea accumulation in anurans. We identified a putative UT from three species of ranid frogs. These proteins were detected in various tissues, with the highest abundance occurring in the osmoregulatory organs. UT protein amount was higher in a terrestrial species than in the more aquatic frogs. To elucidate the role of UTs, we examined the seasonal variation in and effects of osmotic challenge on UT expression in kidney and bladder of the wood frog, Rana sylvatica. UT numbers varied seasonally. Experimental dehydration increased UT amount, whereas experimental freezing had no effect on UT abundance. Experimental urea loading decreased UT abundance. UTs seem to have a role in the adaptation of anurans to osmotically challenging environments, as UTs are involved in solute and water dynamics and are regulated to meet the physiological need to accumulate urea.

Committee: Richard Lee PhD (Committee Chair); Jon Costanzo PhD (Committee Member); Paul James PhD (Committee Member); Andor Kiss PhD (Committee Member) Subjects: Biology; Physiology; Zoology

Master of Science, Miami University, 2007, Zoology

Wood frogs (Rana sylvatica) can accumulate substantial amounts of urea during the winter. In this study maximal urea production capacity is examined in wood frogs collected at various times of the year and in response to experimental hyperuremia and dehydration. Activity and expression of carbamoyl phosphate synthetase I (CPSI), the regulatory enzyme of the urea cycle, are used as indicators of urea production capacity in the wood frog. CPSI activity and expression did change seasonally, though it did not increase in winter. Hyperuremia decreased CPSI activity in hydrated frogs but maintained activity in dehydrated frogs. Changes in CPSI activity were not reflected by similar changes in CPSI quantity suggesting CPSI activity in the wood frog is not primarily being regulated through transcription and translation. Maintenance of urea production capacity in hibernating R. sylvatica probably facilitates accumulation of this osmolyte, which has important roles in the winter biology of this species.

Committee: Richard Lee (Advisor) Subjects:

Master of Science, The Ohio State University, 1970, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1950, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1922, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1916, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Arts, The Ohio State University, 1921, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science (MS), Wright State University, 2024, Biological Sciences

Excess anthropogenic nitrogen (N), primarily from agricultural field fertilization, causes nutrient runoff that stimulates harmful algal blooms (HABs) in western Lake Erie. As a critical tributary to Lake Erie, nutrient loading from the Maumee River drives the intensity of the annual summer HABs in the western basin. Knowledge gaps around rates of N transformations in the Maumee River currently hinder the calibration of in-river parameters in Soil and Water Assessment Tool (SWAT) models for the Maumee watershed. To address these gaps, this research quantified rates of ammonium uptake, ammonium remineralization, nitrification, and bacterial respiration alongside physicochemical parameters of the river. Monthly sampling was conducted along the Maumee River at International Park (river mile 4.53), Mary Jane Thurston (river mile 31.88), and Independence Dam (river mile 59.31) over the course of a year. Ammonium uptake rates ranged from 1.2 to 8.7 µmol N L-1 hr-1 for water samples incubated under light conditions and from 0.2 to 1.9 µmol N L-1 hr-1 under dark conditions, while ammonium regeneration ranged from <0.01 to 12.0 µmol O2 L-1 hr-1. Bacterial respiration rates averaged 525.0 ± 28.5 µM O2. Respiration and both NH₄⁺ uptake & regeneration rates correlated overall with seasonal temperatures and biomass. Respiration rates closely followed temperature, with warmer months having the highest rates. November 2022 samples exhibited higher rates of respiration and both NH₄⁺ uptake & regeneration at all sites as chlorophyll was >200 µg/L during the fall river bloom. Despite not being at peak temperature in the study, the highest rates of microbial activity in April and May., with the lowest observed during the coldest months, January and March. The timing of peak rates at the three sites along the river-to-lake continuum shifted with biomass, indicating the importance of parameterizing the SWAT model with models with spatially and temporally dynamic values. These findin (open full item for complete abstract)

Committee: Stephen J. Jacquemin Ph.D. (Committee Chair); Silvia E. Newell Ph.D. (Committee Co-Chair); Katie Hossler Ph.D. (Committee Member) Subjects: Biogeochemistry; Environmental Management; Environmental Science; Environmental Studies; Hydrologic Sciences; Hydrology; Water Resource Management

BS, Kent State University, 2024, College of Arts and Sciences / Department of Biological Sciences

Agricultural activities can put an exorbitant amount of stress on freshwater ecosystems through land use change, increased erosion, runoff, and excess nutrients or contaminants from fertilizers and pesticides. The fertilizers and pesticides used for agriculture are often changing as seen with the recent increased use of urea-based fertilizers. The effects of urea-based fertilizers on freshwater ecosystems are less studied than the effects of nitrate and ammonium. Urea is an organic source of nitrogen, unlike ammonium and nitrate, and has been shown to have the potential to increase the toxicity of cyanobacteria as well as impacting algal community structure. To test the effects of agricultural stressors on stream ecosystems we utilized a flow-through mesocosm experiment with 30 streams and a gradient design with 5 sediment (0-30 g/L) and 5 urea treatments (0-240 µg/L). We measured algal growth over 22 days (August-September 2023) as chlorophyll a, ash free dry mass and community composition. We assessed urea's effect on nitrogen cycling by measuring ammonium uptake and regeneration. The biofilm community was originally dominated by diatoms and moved toward cyanobacteria throughout the duration of the experiment. Sediment treatment highly influenced biofilm growth with the highest sediment treatments causing the highest cyanobacteria growth. Urea caused a weak non-linear relationship on algal biofilm growth. Increased urea treatment also influenced ammonium uptake and regeneration with the highest urea treatment having the lowest uptake and regeneration rates. This study shows how multiple stressors in stream ecosystems can interact to affect the functioning of the ecosystem. Particularly, excess sediment can inhibit the capacity of algae to take up nitrogen fertilizers, which can exacerbate nutrient loading in sensitive downstream ecosystems.

Committee: David Costello (Advisor); Mark Kershner (Committee Member); Darren Bade (Committee Member); Emariana Widner (Committee Member) Subjects: Aquatic Sciences; Biology; Ecology

Master of Science, The Ohio State University, 2023, Horticulture and Crop Science

Nitrogen is an essential nutrient used in the fertilization of turfgrass systems. Ways to increase efficiency, or reduce the quantity of nitrogen applied, have been studied and implemented into management practices. Nitrification inhibitors, such as dicyandiamide (DCD), have been added to stabilized nitrogen fertilizer blends for their potential to reduce the conversion of soil ammonium to the more unstable nitrate, which has a greater potential to be lost from the soil environment. While stabilized turfgrass fertilizers include DCD, limited data exists for its effectiveness in turfgrass systems. A thorough assessment of DCD would allow for targeted recommendations of its use and limitations. The objective of this study is to evaluate the efficacy of DCD fortified urea in enhancing the duration of turfgrass color, as well as nitrogen efficiency, compared to conventional urea. Both the DCD fortified urea and the conventional urea, at two rates (24 and 44 kg N ha-1 ), were applied to plots of ‘Penncross' Creeping bentgrass (Agrostis stolonifera) in a factorial randomized complete block design with repeated measures. Color analysis, clipping yields, control-adjusted nitrogen offtake, nitrogen recovery efficiency, and soil ammonium and nitrate levels were analyzed. Turfgrass treated with DCD-enhanced urea had a longer duration of color, increased clipping yields, increased control-adjusted nitrogen offtake, and greater nitrogen recovery compared to conventional urea. Soil ammonium and nitrate levels were not significantly affected. DCD appears to increase the duration of nitrogen available to turfgrass, thus leading to a longer duration of color, growth, and greater overall nitrogen efficiency

Committee: Karl Danneberger (Advisor); David Gardner (Committee Member); Edward McCoy (Committee Member) Subjects: Horticulture; Plant Sciences; Soil Sciences

Doctor of Philosophy, Case Western Reserve University, 2022, Molecular Medicine

Cardiovascular disease (CVD) is the leading cause of death worldwide. Traditional risk factors of CVD fail to elucidate the significantly increased CVD risk observed in patients with renal disease. Non-traditional risk factors are thought to contribute to this unexplained risk, through the action of lipoproteins. Historically the lipoprotein high- density lipoprotein (HDL) has been found to be cardio protective through reverse cholesterol transport in epidemiological studies. HDL is a heterogeneous particle comprised of a variety of constituents, the major constituent being apolipoproteinA-I (apoA-I). Post-translational modifications, including but not limited to carbamylation, chlorination, nitration and glycosylation, will render HDL dysfunctional. Evidence suggests that through a process known as protein carbamylation of apoA-I, the particle no longer functions in a cardio protective role but becomes pro-atherogenic. Protein carbamylation occurs through two different pathways. The first is a chemical reaction, which results in response to substantially increased levels of urea observed in chronic and ESRD. The second enzymatic reaction occurs during leukocyte activation of myeloperoxidase (MPO, at sites of inflammation. This process results in the addition of a “carbamoyl” moiety to amines of proteins and amino acids. Studies have been performed analyzing (carbamylated HDL) c-HDL function but have not identified the relationship of site-specific carbamylation of apoA-I/ HDL within human atheroma. As declining kidney function potentially alters the structure and function of c-HDL, the effect of carbamylation becomes increasingly relevant in understanding the pathophysiology of CVD progression. Our goal is to expand our understanding of HDL structurally and clinically through uncovering the site-specific protein carbamylation patterns. We hypothesized that insights into the chemical environment within the human artery wall could be gained by monitoring site-specif (open full item for complete abstract)

Committee: Stanley Hazen (Advisor) Subjects: Biomedical Research

Master of Science (MS), Wright State University, 2021, Earth and Environmental Sciences

Cyanobacteria are important primary producers, but large cyanobacterial harmful algal blooms (HABs) have many negative ecological and health impacts and are becoming increasingly common. Honeoye Lake (New York, USA) is a shallow, eutrophic lake characterized by increasingly frequent HABs. Nitrogen (N) and phosphorus (P) loads often drive HABs in lakes, and sediment processes can contribute to N removal (e.g., denitrification) or loading (e.g., N fixation, remineralization). Sediment cores and lake water were collected during May–October (2016–2018) at two sites and incubated with no amendments (controls) or 15N stable isotopes to measure sediment nutrient fluxes and N cycling dynamics in Honeoye Lake. Sediments were a strong source of ammonium (NH4+; 200 ± 56 µmol N m-2 hr-1) and soluble reactive P (SRP; 1.60 ± 0.67 µmol P m-2 hr-1). Internal loading of NH4+ was greater than previous estimates of external and internal TN loads. In situ denitrification (mean 17 ± 7 µmol N m-2 hr-1) was the main N removal pathway but was limited by NO3- availability and a lack of nitrification (mean 0.007 ± 0.002 µmol N L-1 hr-1). Potential dissimilatory nitrate reduction to ammonium rates (DNRA; 30 ± 11 µmol N m-2 hr-1) suggested sediments may play an important role in internal loading and recycling of N. Water column NH4+ uptake (mean 0.23 ± 0.02 µmol N L-1 hr-1) rates indicated high NH4+ demand, with only 50% of potential uptake being supplied by regeneration (mean 0.11 ± 0.01 µmol N L-1 hr-1) within the water column, while the other 50% can be accounted for from sediment NH4+ loading. Scaling these rates to the whole lake area suggests internal loads of bioavailable N and P are greater than external loads and promote primary productivity and HABs within Honeoye Lake. Shallow lake sediments can be a significant source of reduced N and SRP, which can be mixed periodically supporting HABs. N loads dominated by chemically reduced forms may limit denitrification and favor non-N-f (open full item for complete abstract)

Committee: Silvia E. Newell Ph.D. (Advisor); Mark J. McCarthy Ph.D. (Committee Member); Roxanne Razavi Ph.D. (Committee Member) Subjects: Aquatic Sciences; Biogeochemistry; Environmental Science; Environmental Studies; Geochemistry; Limnology

Master of Science, University of Akron, 2019, Polymer Science

Adequate post-operative pain management has been proven to enhance the healing and recovery of patients following most major procedures.1 However, it remains significantly under managed and is a serious unmet need in the medical field. The mainstay of post-operative pain management is the prescription of oral opioids, which, although effective, have many pitfalls. Most notably, opioids prescriptions are currently based on a “one-size-fits-all” model, providing an imbalance of doses given to patients and leaving the medication at the risk for misuse and abuse. Opioids are still in practice today ultimately due to a lack of a better solution. Herein, we propose a drug-loaded polymer film to control post-operative pain. Poly(ester urea)s were used to load drugs into solvent cast blade-coated films and tested for drug release of non-opioids agents. Specifically, etoricoxib, a selective cyclooxygenase isoform 2 (COX-2) was used to monitor the efficacy of delivery from these films both in vitro and in a rat model. To obtain different release profiles, film thickness, drug-load, and polymer composition was analyzed in order to get desired profile for analgesic release. The polymer analogs that were implemented for this study are copolymers, 10%, 20% and 30% 1-PHE-6 P(1-VAL-8), and homopolymers, P(1-VAL-8), P(1-VAL-10), and P(1-VAL-12). Moreover, a multi-modal analgesia model with bupivacaine (a local anesthetic) has been sought out to show the versatility of this device. The goal of this study was to study a controlled release system that will produce little to no inflammation while providing pain relief for 3-5 days following a surgical procedure. Ultimately, this device's intended purpose is to replace or minimize the need for prescription opioids. We hypothesize that by tuning the multiple factors available with PEUs that a variety of drug release profiles can be obtained to fit a number of different applications (i.e. acute to chronic pain).

Committee: Matthew Becker (Advisor); Andrey Dobrynin (Committee Member) Subjects: Biomedical Research; Polymers

Doctor of Philosophy, University of Akron, 2019, Biology

The reclamation of water from waste streams is a challenge in many industries and applications. Novel filtrations technologies such as forward osmosis (FO) represent energy-efficient alternatives to existing water purification strategies. Recently, aquaporin-based membranes (ABMs) gained increasing attention due to their high water permeability and selectivity. Furthermore, high scalability and robust membrane design make ABMs promising candidates to be further explored and tested in FO. In this dissertation, the potential of water recovery from waste streams and complex solutions such as urine was investigated when using ABMs in FO. First, the rejection capability of a first generation ABM hollow fiber module for three common trace organic contaminants was determined. Overall, high rejection, ranging from 95% to over 99%, could be achieved for all three compounds tested. Furthermore, urea as well as ammonium rejection of an ABM hollow fiber module was investigated under different conditions. While urea rejection did not exceed 53% at high water recovery, the rejection of ammonium at low pH did reach 96%. Based on these findings, strategies to manipulate the urine's chemistry to improve urea rejection by the membrane were investigated. One method tested in this dissertation was the addition of the enzyme urease to artificial urine solutions, which hydrolyzes urea into the charged ammonium ion prior to FO. The proposed treatment resulted in an improvement of total nitrogen (TN) rejection by the FO membrane; however, the increased osmolarity of the resulting feed solution did limit water recovery significantly, outweighing any positive effect brought about by the increased TN rejection. Ultimately, a light-weight and portable FO system, using a second generation ABM hollow fiber module, was evaluated regarding its capability to reduce urine volume by water recovery. While water recovery of 80% could be achieved, 70% of the nitrogenous contaminants could be rejected by (open full item for complete abstract)

Committee: Francisco Moore (Advisor); Hazel Barton (Advisor); Stephen Duirk (Committee Member); Peter Niewiarowski (Committee Member); Petra Gruber (Committee Member); Cristopher Miller (Committee Member) Subjects: Biology; Chemical Engineering; Civil Engineering; Environmental Engineering; Water Resource Management

Master of Science in Chemistry, Cleveland State University, 2018, College of Sciences and Health Professions

Gaussian and GaussView software were utilized to characterize interactions between choline salts and urea, which form a deep eutectic solvent (DES). The initial system studied was choline chloride and urea, at a 1:2 molar ratio, which is also known as reline. Subsequent systems, substituting the chloride anion with other anions (fluoride, bromide, and hydroxide), were studied to show that the system with greater calculated strength of interaction will have more non-ideal physical properties, such as melting point (found in literature). Observations regarding structure related to counterion electron density and hydrogen bonding were made throughout the studies.

Committee: David Ball Ph.D. (Committee Chair); John Turner Ph.D. (Committee Member); Warren Boyd Ph.D. (Committee Member) Subjects: Chemistry

Master of Science, Miami University, 2018, Biology

Enteric bacteria contribute to nitrogen balance in diverse vertebrates because they produce urease, the enzyme needed to liberate nitrogen from urea. Although this system of urea-nitrogen recycling is as yet unknown in Amphibia, this study of the wood frog (Rana sylvatica), a terrestrial hibernator that is strongly hyperuremic during winter, documented robust urease activity in bacteria inhabiting the hindgut. Despite a ~33% reduction in the number of bacteria, ureolytic capacity in hibernating winter frogs was superior to that of active summer frogs, and was further enhanced by experimentally augmenting urea within the host. Bacterial inventories constructed using 16S rRNA sequencing revealed that the assemblages hosted by hibernating and active frogs were equally diverse but markedly differed in community membership and structure. Approximately 38% of the 96 observed bacterial genera were exclusive to one or the other group. Although ~60% of these genera possess urease-encoding genes and/or have member taxa that reportedly hydrolyze urea, hibernating frogs hosted a greater relative abundance and richer diversity of ureolytic organisms, including, notably, species of Pseudomonas and Arthrobacter. Amphibians, in whom urea accrual has a major osmoregulatory function, likely profit substantially by repurposing the nitrogen liberated from the bacterial hydrolysis of urea.

Committee: Jon Costanzo (Advisor); Richard Lee Jr. (Advisor) Subjects: Biology; Physiology