Physical Sciences and Mathematics Commons^™

Application Of Functionalized Organosilicas In Adsorption Of Nitrates, Stephen Amoako

Electronic Theses and Dissertations

This study addresses the critical environmental issue of elevated nitrate levels in water bodies, primarily due to excessive use of nitrogenous fertilizers and improper waste disposal. It focuses on reducing nitrate concentrations in polluted water to permissible levels through the effectiveness of hybrid materials in nitrate adsorption. We synthesized nine amino-functionalized adsorbents using grafting and sol-gel techniques. Batch adsorption tests confirmed the high nitrate adsorption capacities of these adsorbents, with sol-gel materials showing the highest efficiency due to their abundant amino group contents. Among these, the surfactant-free, sol-gel adsorbent was the most effective, combining ease of synthesis with cost-efficiency. Our …

Synthesis And Characterization Of Indole-Based Zinc Dipyrrin Photosensitizers, Jean-Pierre Sanza

Electronic Theses and Dissertations

Metal complexes of dipyrromethene (dipyrrins) used as sensitizers in photocatalysis offer a way to harness solar energy in chemical bonds to create new fuels. This offers the dual role of reducing fossil fuel dependence and atmospheric CO₂ levels. Traditionally, metal dipyrrin complexes are synthesized using substituted pyrroles, aldehydes, and transition metals. Indoles have a more expanded pi-electron system and their dipyrrin-type complex may exhibit visible light absorption, suggesting that they can act as photosensitizers for CO₂ reduction processes. A novel indoledipyrromethene was synthesized using unsubstituted indole and mesitaldehyde. The complex exhibits visible light absorption at 422 nm. Its …

Medicinal Mushrooms: The Extraction And Analysis Of Bioactive Compounds From Hericium Erinaceus And Ganoderma Lucidum Mushrooms., Jhanielle Amanda-Kaye James

Electronic Theses and Dissertations

Medicinal mushrooms, such as Hericium erinaceus (lion's mane) and Ganoderma lucidum (reishi), have a rich history of traditional use in natural remedies, garnering attention for their bioactive compounds and nutritional benefits. Renowned for being protein-rich and low in fat, these fungi exhibit antimicrobial, anti-tumor, antioxidant, anti-diabetic, and anti-hypercholesterolemic properties attributed to their diverse bioactive components, including polysaccharides, proteins, terpenes, sterols, vitamins, polyphenols, and fatty acids. This study aimed to optimize extraction techniques, comparing maceration, ultrasound-assisted maceration, and Soxhlet extraction on fresh and dried lion's mane and reishi mushrooms. Varying solvent polarities and extraction times revealed that 8-hour extractions with dried …

Dynamic Metal-Ligand Interactions In Semiconducting Π-Conjugated Materials, Peter Blake Joseph St Onge

Electronic Theses and Dissertations

Over the years, the development of materials has seen a vast amount of expansion into a variety of disciplines which have demonstrated usefulness in a large span of applications. One of these new and developing themes is the use of metals and ligands which are incorporated into polymers to modify their properties, which can enable different desired properties. Incorporation of metal-ligand complexes in materials chemistry has proven to be an area of rising interest, however, many of these interactions and systems remained completely unexplored. Understanding the key fundamental principles of how these materials can be changed and modified through metal-ligand …

Impact Of Solar Radiation On Perchlorate Formation In The Atmosphere: Evidence From Ice Core Measurements, Bishnu Kunwar

Electronic Theses and Dissertations

Perchlorate, which derives from both anthropogenic and natural sources in the current environment, poses a substantial health hazard to humans as it competes with iodine uptake in the thyroid gland. Consequently, there has been considerable concern about minimizing human exposure to environmental perchlorate by restricting its release from man-made sources. However, the absence of a clear understanding regarding the respective contributions of man-made and natural sources has hindered widespread regulation efforts. A 300-year (1700–2007) Summit, Greenland ice core record from a previous study showed relatively stable perchlorate concentrations in Greenland snow prior to 1980, with some elevated perchlorate levels associated …

Problems In Chemical Graph Theory Related To The Merrifield-Simmons And Hosoya Topological Indices, William B. O'Reilly

Electronic Theses and Dissertations

In some sense, chemical graph theory applies graph theory to various physical sciences. This interdisciplinary field has significant applications to structure property relationships, as well as mathematical modeling. In particular, we focus on two important indices widely used in chemical graph theory, the Merrifield-Simmons index and Hosoya index. The Merrifield-Simmons index and the Hosoya index are two well-known topological indices used in mathematical chemistry for characterizing specific properties of chemical compounds. Substantial research has been done on the two indices in terms of enumerative problems and extremal questions. In this thesis, we survey known extremal results and consider the generalized …

Elucidating The Pd Active Sites Of Bimetallic Gold-Palladium Catalysts Using Chemisorption And Titration Techniques, Andrew T. Boucher

Electronic Theses and Dissertations

A bimetallic nanoparticle catalyst combines two different metals on an oxide support, which can increase the selectivity towards useful products that may be too tightly bound to a monometallic catalyst. To explore the surface properties of such a system, we made a group of four PdAu bimetallic catalysts with varying gold mass loadings to compare with a parent Pd catalyst. The parent catalyst was synthesized using ion exchange, and gold was added to this parent Pd catalyst using incipient wetness impregnation (IWI) to create four bimetallic catalysts. All catalysts were characterized using H₂ and CO chemisorption in tandem with …

Advances In Cellulose Nanomaterial-Based Foams For Environmental Applications, Md Musfiqur Rahman

Electronic Theses and Dissertations

The use of metal-oxide nanoparticles adsorbents is limited to fixed-bed columns in industrial-scale water treatment applications. This limitation is commonly attributed to the tendency of nanoparticles to aggregate, the use of non-sustainable and inefficient polymeric resins as supporting materials, or a lack of adsorption capacity. Foams and aerogels derived from cellulose nanomaterials have unique characteristics, such as high porosity and low density, which enables their use in a variety of environmental applications, including water treatment. However, the overall use of cellulose nanomaterial-based foams in various environmental sectors is limited due to the high cost of production associated with time- and …

Synthesis Of Poly(Styrene-Co-Butyl Acrylate) Pickering Emulsion With Montmorillonite Nanoparticles And Its Comparison With Sodium Dodecyl Sulfate Surfactant On Affecting The Water Barrier Properties Of Coated Paper, Chidubem H. Uchefuna

Electronic Theses and Dissertations

Water-borne barrier dispersion coatings on paper have emerged as an alternative to extrusion coatings on paper due to improved recycling, high application speed, and other end of life attributes. Pigments are often added to improve the performance of dispersion coatings. The use of pigments to form a Pickering emulsion during the polymerization step for the production of a barrier coating on paper has not been discussed in the literature.

In this study, montmorillonite (MMT) pigment varied from 0-6 % pigment volume concentration (PVC) was used to synthesize dispersion coatings consisting of poly(styrene-co-butylacrylate) latex and compared with sodium dodecyl …

Scalable Solution Processing Of Niox Nanoparticles., Peter James Armstrong

Electronic Theses and Dissertations

Perovskite solar cells (PSCs) are a promising alternative to silicon-based photovoltaics. However, PSCs face several challenges due to shortcomings in their stability, module efficiency, and scaled production. Although PSCs is still a young field of research, significant attention has been given to demonstrating power conversion efficiencies that are on par with traditional silicon. With that target reached, converting the laboratory demonstration into practical materials to increase access and abundance of solar energy are among the next large targets for the field. This comes with material challenges for perovskite and their companion charge transport layers (CTLs). Among the charge transport materials …

Computational Investigations Of Bond Breaking Processes Using Dft And Td-Dft Approaches., Saurav Parmar

Electronic Theses and Dissertations

The efficient application of DFT and TD-DFT has been harnessed to study bond-breaking processes in some molecules which play a prominent role in enzymatic reactions. The first application includes Radical S-adenosyl methionine (SAM) enzymes which are fundamentally important sources of organic radicals to initiate diverse radical reactions. Recently a bio-organometallic intermediate (Ω) that contains an Fe‒C bond has been characterized and shown to be a common feature of radical SAM enzymes. The strength of Fe‒C bond in Ω has been computed using broken-symmetry density functional theory (BS‒DFT). Additionally, Fe‒C bond dissociation energy (BDE) in Ω has been compared to that …

Computational Quantum Chemistry Studies Of The Stabilities Of Radical Adducts Formed During The Oxidation Of Melatonin Derivatives, James Horne

Electronic Theses and Dissertations

Melatonin is a natural antioxidant that has been investigated for properties as a potential spin trap to identify short-lived free radicals. Computational quantum chemistry studies have been performed for the oxidation of melatonin to N¹-acetyl-N²-formyl-5-methoxykynuramine. This research focused on modification of melatonin into derivatives and analyzing the change in total molecular energy from melatonin to its oxidation product, as well as the corresponding derivatives. Each of the molecular geometries were optimized at the DFT/B3LYP/6-31G(d), DFT/B3LYP/cc-pVXZ (X = D, T), HF/6-31G(d), HF/cc-PVXZ (X = D, T), MP2/6-31G(d), and MP2/cc-PVXZ (X = D, T) levels of theory. …

Electrodeposition Studies Of Gold Nanoparticles And Alginate Hydrogel Films., Harikrishnan Nambiathan Nambiar

Electronic Theses and Dissertations

This dissertation investigates the electrochemical deposition (ECD) and electrophoretic deposition (EPD) processes involving citrate (cit)-stabilized Au nanoparticles (NPs) and calcium alginate (Ca-Alg-Au NP) hydrogel films. The first part of the dissertation investigates the influence of NP size, surface area (SA) coverage, and ligand stabilizers on the electrochemical growth of Au on Au NPs, aiming to enhance our understanding of the growth process during the nucleation and growth of metal NPs. The growth kinetics depend on Au NP size (4 nm > 15 nm > 50 nm) for a constant SA coverage, as determined by the overpotentials for ECD. The growth rate increases …

Synthesis Of Bacterial Glycerophospholipids For Biomembrane Model Studies: A Means To Advanced Biofuels, Felix Adulley

Electronic Theses and Dissertations

To reduce reliance on fossil fuels, sustainable biofuels are being pursued, especially advanced biofuels like 1-butanol that have higher energy content and greater compatibility with existing infrastructure than ethanol. A persistent challenge is the yield-limiting toxicity of biofuels and process solvents, such as tetrahydrofuran, to the microbes that ferment biomass into biofuel. The cell membrane is a focal point of toxicity, and understanding how it interacts with fuels and solvents is key to improving yield. Phospholipid bilayers are the core of biomembranes, and model biomembranes of defined composition provide the ideal platform for biophysical studies. To this end, glycerophospholipids characteristic …

Exploring Paper As A Substrate For Printed Electronics, Lauren Jessica Renaud

Electronic Theses and Dissertations

With the Internet of Things (IoT) rapid expansion the use of printed electronics that can be easily integrated into everyday life is gaining traction. These devices often use plastics as a substrate due to their flexibility; however, they are not biodegradable and contribute to our growing electronic waste (e-waste) problem. A greener alternative that is sought after is paper. Paper is biodegradable, flexible, and already familiar to many printing processes. Though paper appears smooth its surface is rough due to being composed of cellulose fibers which create pores. In the printed electronics (PE) industry, these pores are typically seen as …

Developing New Strategies Towards The Fabrication Of Flexible, Organic Electronics, Daniella Skaf

Electronic Theses and Dissertations

An investigation into the use of greener dielectric and substrate materials, specifically shellac and paper, was done through the development of paper-based organic thin film transistors. Shellac and paper both hold advantageous properties that were explored in Chapter III, through the optimization in the fabrication of the devices and an evaluation of the electrical properties of these newly developed organic transistors. Different designs were explored using two common DPP-based polymers, P(DPP-T) and P(DPP-TVT), as the active materials, with Design #2 (bottom-gate top-contact) proving to be the best performing device according to the on/off ratio, charge mobilities and threshold voltage. Shellac …

Expanding Glycomic Investigations Through Thiol-Derivatized Glycans, Robert Hurst

Electronic Theses and Dissertations

N-(2-thioethyl)-2-aminobenzamide (TEAB), a novel glycan auxiliary, was synthesized and its utility was evaluated. The auxiliary was conjugated to glycans by reductive amination with the water-stable reagent 2-picoline borane complex. Glycan products, which ranged from 1 to 7 linked hexoses, were all isolated in yields ranging from 60% to 90% after purification by reverse-phase chromatography. The novel conjugate introduces a convenient, shelf-stable thiol directly onto the desired free glycans with purification advantages and direct modification with efficient reactions through alkenes, halides, epoxides, disulfides, and carboxylates in yields of 49% to 93%. Subsequently, a thiol-selective modification of the BSA protein was used …

Supramolecular And Covalent Crosslinking Of Organic Semiconductors, Audithya Narasimha Nyaychavadi

Electronic Theses and Dissertations

Organic semiconductors are a class of materials that are uniquely positioned to be the platform for next generation technologies that possess properties that transcend the limitations of silicon materials such as inherent biocompatibility, stretchability and degradability, all while being manufactured sustainably and at lower cost. These materials have good electronic properties that arise from their π-delocalized network, which when combined with rational chemical design allow for highly specialized materials for targeted applications and properties. Furthermore, their ability to be solution processed provides an avenue for low-cost, scalable mass production techniques, such as printing and roll-to-roll coating. Despite these advantages, however, …

Dinitroxides In Rapid Scan Electron Paramagnetic Resonance Imaging, Lukas B. Woodcock

Electronic Theses and Dissertations

Local tissue physiology is an important parameter in understanding disease behavior. Rapid Scan (RS) electron paramagnetic resonance (EPR) offers a unique, non-invasive tool for investigation of these so-called microenvironments through EPR Imaging (EPRI). Research into advancement of EPRI falls into many categories. Not least among those are advances in instrumentation and methodology. Presented here are updates to a benchtop EPRI instrument operating at 1 GHz targeted at pre-clinical EPRI applications. Newly developed methods for reducing RS-EPR background through inversion of the magnetic field are also demonstrated. EPR applications are limited in native biological systems due to the miniscule concentration of …

New Methodologies For Sustainable Organic Synthesis In Water., Sudripet Sharma

Electronic Theses and Dissertations

Water is stable, benign, and green solvent. Its usage as a solvent in organic synthesis is significantly enhanced by micellar catalysis. However, replacing water as a reaction medium in organic synthesis is not sufficient to meet the sustainability challenges—excessive organic solvents are still required for product isolation and purification. Notably, solvents used in syntheses contribute to more than 80% of waste generation. In addition to solvents, the use of palladium in large amounts is also a problem for the future as it is a precious, low-abundance metal, and its supply is dwindling. Therefore, this dissertation highlights the various sustainable protocols …

Development And Applications Of Novel And Practical Fluorination Reagents., Yuhao Yang

Electronic Theses and Dissertations

The fluorine (F) atom has distinctive properties such as the highest electronegativity, small size, low polarizability, and strong C–F bond strength. Not surprisingly, fluorinated organic compounds have garnered significant attention in the pharmaceutical, agrochemical, and material fields. Since organofluorides are very rare in nature, we need fluorination reagents to help us transfer fluorine into the organic molecules. In past decades, a vast number of fluorination reagents have been developed and many of them are commercially available now. However, there is still much room for the improvement of these reagents. Our target is to develop novel and practical fluorination reagents to …

Optimization Of Equilibrated Headspace Technique For Compositional And Isotopic Analysis Of Dissolved Gases, Michelle Tsuey-Yee Quan

Electronic Theses and Dissertations

Dissolved gas analysis has been used to quantify concentrations of natural gas and carbon dioxide in solutions for many years, giving insight into bioremediation processes and potential natural gas releases. However, due to the lack of universal dissolved gas methods, there is room for interpretation during sampling, storage, and analysis, causing variation in the data obtained between laboratories, especially as these techniques are often not applicable to stable isotope analysis, which can be used to determine the source of the elevated concentration obtained. Thus, one portion of this thesis aims to gain a greater understanding of the effect of headspace …

Influence Of Platinum Nanoparticles On Ionic Transport And Hydrogen Reactivity Of Yttria-Stabilized Zirconia Thin Films, Firas Mahyob

Electronic Theses and Dissertations

Yttria-stabilized zirconia (YSZ) is a widely used ceramic material in solid oxide fuel cells, oxygen sensors, and sensing applications due to its high ionic conductivity, chemical inertness, and thermal stability. YSZ is promising active coating for use in miniaturized harsh environment wireless surface acoustic sensors to monitor gases such as H₂. Adding catalytic Pt nanoparticles can enhance gas reactivity and lead to associated film conductivity changes.

In this work, thin films with an (8% Y₂O₃ - 92% ZrO₂) composition were deposited onto piezoelectric langasite substrates using RF magnetron sputtering in Ar:O₂ - …

Quantum Mechanical Studies Of Water Splitting Reaction With (Zno)3 Nanoclusters As Catalysts, Duwage C. Perera

Electronic Theses and Dissertations

With the current energy crisis, H₂ production through the water-splitting reaction has drawn attention recently. In this thesis, I studied the structural (geometry) and electronic properties (vertical detachment energy and electron affinity) of ZnO monomers and dimers using density functional theory. ZnO is a metal oxide with a 3.37 eV band gap and can be a commercially cheaper photocatalyst in hydrogen (H₂) production. The B3LYP/DGDZVP2 pair was selected after investigating different pairs of exchange functionals and basis sets to study the hydration, hydrolysis, and water-splitting reaction. The singlet-triplet energy gaps of small (ZnO)_n clusters (n=1-6) of …

The Study Of Corrosion On Additive-Manufactured Metals., Braydan Daniels

Electronic Theses and Dissertations

The purpose of this study was to investigate and compare the corrosion mechanisms between wrought and additive-manufactured (3D-printed) copper and stainless steel. The experimental procedure consisted of measuring the open circuit potential, electrochemical impedance spectroscopy, linear sweep voltammetry, Tafel analysis, surface topology, and scanning electron microscopy for each metal within salt water, tap water, sulfuric acid, and synthetic body fluid (excluding copper in synthetic body fluid).

Overall, printed stainless steel was more corrosion-resistant than wrought stainless steel in tap water and synthetic body fluid based on OCP, LSV, and surface topology results. Additionally, printed copper was more corrosion-resistant than wrought …

Development Of Nonorthogonal Wavefunction Theories And Application To Multistate Reaction Processes., Emily Kempfer

Electronic Theses and Dissertations

Many prominent areas of technological development rely on exploiting the photochemical response of molecules. An application of particular interest is the control of molecular switches through a combination of different external stimuli. However, despite significant advances in theoretical approaches and numerous cases of successful application of theory, simulating photochemical reactions remains a computational challenge. Theoretical methods for describing excited states can be broadly divided into single-reference response methods and multireference methods. Single reference methods provide reliable semiquantitative results for single excitations. However, these methods cannot describe double-excited states, systems with strongly correlated ground states, or regions of degeneracy on the …

Structural, Magnetic, Electrical, Pseudocapacitive, And Electrocatalytic Properties Of Bilayered Ruddlesden-Popper Oxides., Chandana Kananke-Gamage

Electronic Theses and Dissertations

Ruddlesden Popper (RP) oxides are perovskite-derived functional materials with the general formula An-1Aʹ2BnO3n+1, where A/Aʹ is often a lanthanide or alkaline earth metal, and B is usually a transition metal. These materials contain perovskite-like connectivity, where BO6 units share apexes to form layers that are stacked above each other. The number of layers in each stack is represented by n in the above formula. The spaces between stacks are often occupied by lanthanide or alkaline-earth metals (Aʹ-site metals), which also reside in intra-stack spaces (A-site) between the octahedra. Oxide materials derived from perovskites have been studied for a wide range …

Enzymatic Removal Of Diclofenac And Aceclofenac From Synthetic Wastewater By Soybean Peroxidase, Sarah Pishyar

Electronic Theses and Dissertations

Pharmaceutical medications that are a class of emerging contaminants have been detected in wastewater treatment facilities' influent and effluent, and they have reached water sources in amounts ranging from ng/L to ug/L. They threaten the environment and non-target life. Soybean peroxidase (SBP)-catalyzed process was studied to remove two non-steroidal anti-inflammatory drugs (NSAIDS) diclofenac and aceclofenac through enzymatic oxidation from synthetic wastewater. SBP can be extracted from soybean hulls, a by-product of the soybean industry. First, the experiments studied the viability of SBP-catalyzed removal on these two compounds, then the operational parameters including pH, the molar ratio between hydrogen peroxide and …

Enzymatic Removal Of Sulfa Drugs From Synthetic Wastewater By Soybean Peroxidase, Maryam Sharifzadeh

Electronic Theses and Dissertations

Sulfa drugs are a broad family of antibiotics that are widely used in the treatment of a wide range of infections, and they have been found in surface and groundwater, as well as present in sewage and effluent (treated sewage and sludge)municipal or industrial wastewater treatment plants (WWTPs). in concentrations of ng/L to >g/L. The continued presence of these so-called emerging pollutants (ECs) and their metabolites can cause adverse ecological effects, including bacterial resistance, even at very low concentrations. In this study, the first aim was to explore the feasibility of oxidation processes catalyzed by soybean peroxidase as an eco-friendly …

Advanced Analytical Techniques For The Analysis Of Toxic Inhaled Agent Exposure And Pharmacokinetic Investigation, Sharmin Sultana

Electronic Theses and Dissertations

Toxic inhalation agents (TIAs) (i.e., chlorine (Cl2), cyanide (HCN), etc.) are highly poisonous. However, they have a variety of industrial uses, such as health, agro-food, building, textiles, transport, leisure activities, cosmetics, etc. In addition, TIAs can be used as chemical agents in terrorist events or conventional warfare. The ability to detect TIAs in biological and environmental samples is important for preparing use, determining individual exposure, limiting hazardous exposure, etc. Therefore, developing simple and sensitive analytical methods for TIAs, TIA metabolites, and antidotes for those toxic agents is very important. The focus of this study was chlorine and cyanide. Chlorine is …