Physical Sciences and Mathematics Commons^™

Cognitive Engagement During Group Learning Activities In Chemistry Courses: An Analysis Of Student Discourse, Safaa Youssef El-Mansy

Dissertations and Theses

As educators, our goal is to help our students be successful, but in order to accomplish this, we need to understand what factors contribute to student success. One factor, small-group active learning, has been correlated to improved academic outcomes; however, the magnitude of this improvement can vary across different courses, different types of group work, and even across courses that use the same group work structure. Therefore, it is important to understand what aspects of group work contribute to its effectiveness. The work presented in this dissertation investigated one specific aspect: students’ cognitive engagement. This was done by analyzing the …

Electrochemical Hydrogen Gas Production And Carbon Dioxide Sequestration Via In Situ Formation Of Nickel (Ii) Tris-(Pyridinethiolate) Derivatives, Dayalis S.V. Brown

Dissertations and Theses

In the research presented, we use electrochemical techniques, such as cyclic voltammetry and controlled potential electrolysis, to study in situ formation of hydrogen evolution catalysts which also reduce carbon dioxide. Using pyridinethiol-based ligands and a nickel (II) precursor, both homo- and heteroleptic complexes were investigated as catalysts to produce alternative fuels while mitigating greenhouse gas emissions. Existing synthetic procedures to obtain these Ni(II) catalysts lead to low yields of the complexes and difficulties in crystallizing samples for further analysis, limiting sample size and restricting the number of studies. While current research is heavily focused on photochemically-driven experiments, given that solar …

Studies On Bonding, Syntheses, And Applications Of Diarylhalonium Compounds, Shubhendu Karandikar

Dissertations and Theses

Organic compounds containing functionalized benzenoid rings have found tremendous applications in pharmaceuticals, agrochemicals, commodity chemicals, and beyond. As a result, development of methods for the synthesis of functionalized benzenoid rings has gained much attention from the synthetic community. Although many transition-metal mediated methods to functionalize benzenoid rings are known, there has been an upsurge of activity in developing protocols for decoration of benzenoid cores promoted by p-block elements. This excitement stems from the sustainability of earth-abundant elements and unique reactivity patterns observed within the p-block. Among these, transformations promoted by hypervalent halogen compounds, and especially, the diarylhalonium salts are very …

Drug Delivering Properties Of Novel Materials For Dentinal Desensitization, Abu Ahammadullah

Dissertations and Theses

This study focuses on the development of non-toxic dental materials that can adhere to dentin, occlude dentinal tubules, and release a drug with or without biological triggers. The properties of those materials are examined by SEM, UV-vis absorption spectroscopy, and a fluoride-selective electrode. The study also investigates the surface modification of calcium carbonate surface with casein, which stabilizes its micro-and nanoparticles in aqueous suspensions, making them suitable for use in dentifrices. The results indicate that the morphology and composition of the particles affect their ability to hold and release eugenol, with the casein-coated calcium carbonate microspheres being the most acid-sensitive …

Developing Mesoporous Silica Nanoparticle-Based Stimuli-Responsive Nanocarriers For Delivery Of Small Molecule Therapeutics Against Colon Cancer Cells, Nisitha Lakmal Wellala Wijewantha

Dissertations and Theses

This dissertation delves into the innovative application of mesoporous silica nanoparticles (MSNs) for targeted drug delivery in colorectal cancer (CRC), one of the most prevalent and deadly forms of cancer worldwide. The initial focus of the research is on developing enzyme-responsive MSNs loaded with veratridine (VTD), an alkaloid derived from natural sources that demonstrates potent anticancer activity. The nanoparticles have been engineered to deliver VTD selectively to CRC cells, releasing the payload upon being exposed to specific enzymes primarily secreted by these cells. This strategy has dual advantages of amplifying the anticancer effects while minimizing potential side effects on healthy …

Nmr Analyses Of Flavored E-Cigarette Liquids Before And After Aerosolization, Paul Joseph Kerber

Dissertations and Theses

Electronic cigarettes (e-cigarettes) are the most commonly used tobacco products among adolescents with ~11 and ~3% of high school and middle school students reporting past 30 day use in 2021 according to the Centers for Disease Control and Prevention (CDC), respectively. Furthermore, greater than ~80% of high school and middle school e-cigarette consumers use flavored e-liquids. Consumers can be exposed to variable toxicant levels upon e-liquid aerosolization, depending on the composition of the e-liquid, type of e-cigarette, e-cigarette settings, and other customizations.

E-liquids are typically composed of a carrier solvent (propylene glycol (PG) and glycerol (GL)), flavorants, and nicotine. PG …

Exploring Structure-Function Relationship In Small-Molecular Catalysts Using Computational And Experimental Methodologies, Avik Bhattacharjee

Dissertations and Theses

Molecular modeling is a useful tool in the field of catalyst design for various processes. The use of Density Functional Theory (DFT) is routine in almost every discipline of chemistry. This allows for a deeper understanding of a molecular system even in situations where implementation of an experimental technique is unfeasible. However, without the right choice of theory and insufficient description, the model becomes susceptible to produce ambiguous results. This often leads to poor correlation with experimental findings hence an incomplete understanding of the system under study. Hence, to acquire a thorough knowledge of the intricacies involved in a system, …

Synthesis Of Diaryl And Alkyl-Aryl Ethers Via Diaryl Iodonium Reagents, Rory Tennessee Gallagher

Dissertations and Theses

Substituted benzenoid rings are a prevalent motif in many industries including high tech, agrochemicals, and pharmaceuticals. As a result, the arylation of chemical compounds is a highly sought-after chemical transformation. There are many literature methods to achieve this chemical transformation, nucleophilic aromatic substitution and transition metal catalysis are both widely used and studied. Diaryliodonium salt mediated chemistry is an attractive alternative to these methods as it does not require the expensive toxic metals and designer ligands of transition metal catalysis and is not restricted to electron deficient aryl rings with specific substitution patterns like nucleophilic aromatic substitution.

Many diaryliodonium salt …

Efficient Capture Of Co2 And Its Selective Reduction To Formic Acid Using Tin-Based Nanomaterials, Emmanuel Oluwaseun Abdul

Dissertations and Theses

CO₂ emissions from the combustion of fossil fuels and other anthropogenic sources have become the main contributing factors to global warming. Chemical methods of absorbing/capturing CO₂ from combustion flue gases have made it a sought-after approach in engineering emission solutions because of its simplistic and convenient operation and high absorption efficiency. The conversion of CO₂ into renewable fuels and high energy density chemicals by clean and economic processes has drawn scientists' attention over the decades. The electrocatalytic conversion of CO₂ using Sn-based materials has been demonstrated to be a promising method for producing formate, an important …

Speciation Of Diaryliodonium Salts In Solution And Their Reactivity Towards N-Nucleophiles (Phthalimide And Amines) And O-Nucleophiles (Phenols And Phenoxide), Souradeep Basu

Dissertations and Theses

Benzenoid rings are prevalent in pharmaceutical drug molecules, agrochemical molecules and even in some polymers used in electronic device. Aryl rings are often installed using metal catalysis, however, metal free arylations are known but limited. Diaryliodonium salts are novel electrophilic arylating agents. Herein, metal free N-arylation of phthalimide and diarylether formation using aryl(TMP)iodonium salts is described.

The structure of diaryliodonium salts has been primarily studied in either the solid state or in-silico. The structure and speciation of diaryliodonium salts in solution is not well explored. In this work evidence of dimer formation of aryl(Mes)iodonium salts in chloroform using …

A Biomimetic Model For Oxidative Metabolism Of Thiopurine Drugs, Oluyemi Oludare Alo

Dissertations and Theses

Type B hepatotoxicity has been reported for thiopurines, and this has limited their clinical uses. Although a lot of research has been done on thiopurines, the precise mechanism of their hepatotoxicity is still unclear. The results of the in vitro and in vivo experiments aimed at assessing the products of their CYP450-mediated bioactivation have been contradictory. Although it has been theorized that the hepatic toxicity of this class of drug is caused by their bioactivation to electrophilic reactive metabolite (RM) and concomitant protein binding to form immunogenic adducts, resulting in direct cellular dysfunction or an immune response via the formation …

Materials And Methodologies For Spectroscopic And Optical Analytical Applications In Cultural Heritage Conservation Science, Lyndsay Nichole Kissell

Dissertations and Theses

The field of conservation science falls in the intersection of science and art. The work of conservation scientists may include any single subdiscipline of chemistry, though it is most commonly a highly interdisciplinary field taking skills from analytical, organic, and inorganic chemistry, as well as surface and materials science. The aims of conservation scientists are to answer questions about the production and aging of material cultural heritage. Knowing the materials used by an artist can lead to insight about the intentions of the object and knowing how those materials degrade will enable the use of preventative measures to ensure the …

Investigating Synthetic Methods For Tio2-Nayf4 Hybrid Nanocrystals, Nurul Muttakin

Dissertations and Theses

The capacity to develop and expand the utility of a single nanostructure is one of the major issues in the field of hybrid nanocrystals. Major advancements in the fabrication of materials with multiple functionalities by combining many materials into a single nanoparticle entity are intriguing, but they still pose obstacles that must be addressed. This trend has been spurred by significant progressions in the wet-chemical synthesis of durable and easily programmable nanocrystals with various morphologies. The extent of the structural complexity of solution-based nanocrystals looks to be one of the inevitable avenues along which nanoscience will increasingly focus. We have …

Computational Study Of Quorum Quenching Of N-Acyl Homoserine Lactones By Ion Pairing To Cations, Ashen Anuradha Suduweli Kondage

Dissertations and Theses

Biofilms are the default state of microbial life and their formation on surfaces influences many processes. The coordinated behavior of microorganisms including their growth into biofilms occurs through a process termed quorum sensing during which they excrete specific signaling molecules called autoinducers. Recently it has been observed that Ag+ and Cu2+ ions interact with N-hexanoyl-L-homoserine autoinducers thereby inhibiting quorum sensing. Such inhibitors are called quorum quenchers. In this study, we have used density functional theory (DFT) calculations to study the ion pairing between select cations and short chained N-acyl-homoserine lactone (AHL) type autoinducers that are used by gram negative bacteria. …

Nonhematopoietic Erythropoietin: A Study Of Signaling, Structure, And Behavior, Nicholas John Pekas

Dissertations and Theses

Erythropoietin (EPO) is a cytokine hormone known for initiating red blood cell proliferation by binding to its homodimer receptor (EPOR)2 in the bone marrow. Recent progress in neurobiology has shown that EPO also exerts robust neurotrophic and neuroprotective activity in the CNS. It is widely thought that EPO’s neurotrophic activity is centrally involved in its antidepressant and cognitive enhancing effects. However, EPO’s potent erythropoietic effects prevent it from being used in the clinic to treat psychiatric disorders. A chemically engineered non-erythropoietic derivative of EPO, carbamoylated EPO (CEPO), produces psychoactive effects without activating hematopoiesis. However, CEPO is expensive to produce and …

Analysis Of Blue Fountain Pen Ink By Uv-Vis Spectroscopy, Atr-Ftir Spectroscopy, And Thin Layer Chromatography Enhanced With Rgb Spot Evaluation To Construct A Database For Comparison And Identification., Elliot D. Quinteros

Dissertations and Theses

Pen ink can be a crucial piece of physical evidence in the area of Forensic Science. For example, evidence such as notes, letters, printed documents, checks, currency, ransom notes, and books may contain ink. Analysis of ink is typically done for identification or differentiation purposes. To improve existing methods, it was proposed to create a database with many samples and experimental information. The methods used and evaluated were thin-layer chromatography (TLC) enhanced with RGB spot evaluation, UV-Vis spectroscopy, and ATR-FTIR spectroscopy. All three methods were used to analyze 89 fountain pen ink samples. All three methods were able to discriminate …

Selective Oxidation Of Alkenes In Air Catalyzed By Mn3o4 Nanoparticles, Brojo Kishor Shachib Dhali

Dissertations and Theses

Catalytic oxidation is a process where compounds are oxidized using catalysts. Solid catalysts exhibit several advantages over homogeneous systems, such as catalyst recovery and excellent stability. Various supported transition-metal oxides (for example: CuO, ZnO, CeO2, Fe2O3 and WO3), metal nanoparticles (for example: Pd and Ru) and polyoxometalate clusters (for example: [W10O32]4-, [Mn2ZnW(ZnW9O34)2]10- and [XW12O40]n- (X = P, Si)) have been applied to selective oxidation of organic compounds, but high associated product conversion still remains a challenge. Recently, a number of materials containing Mn3O4 have been used successfully in different catalytic applications, such as degradation of phenols, reduction of nitrobenzenes, and …

Exploring The Potential Use Of Porous Silica Nanoparticles In Cest-Mri, Lydia Makotamo

Dissertations and Theses

Magnetic resonance imaging (MRI) is a widely used modality in diagnostics, treatment, and monitoring various conditions due to its ability to generate high-resolution images using non-ionizing radiation. The advent of contrast agents, which generally work by increasing the spin relaxation rate constants of water protons, has led to image enhancement. Despite the usefulness of this class of agents in diagnostic medicine, their inability to provide in-depth functional and anatomical information, coupled with their high detection limits, has led to new agents being explored.

Chemical exchange saturation transfer (CEST) presents an alternative route to generate signals via repetitive saturations transfers between …

Designing Environmentally Responsible And Highly Effective Bioorthogonally Functionalized Chiral Mri Contrast Agents, Karley Breann Maier

Dissertations and Theses

Magnetic resonance imaging (MRI) revolutionized diagnostic imaging and modernized the characterization of numerous diseases. The clinical success of MRI is in large part due to the employment of gadolinium-based contrast agents (GBCAs). Due to sensitivity limitations, GBCAs are indicated at markedly high dosages (~1 g Gd³⁺ per exam). The routine use of such large quantities of gadolinium poses significant health and environmental risks. There are growing concerns over the effects of dechelation of the metal in vivo and the possible effect of resulting gadolinium deposition. Concurrently, there is a rising awareness of gadolinium anomalies borne by GBCAs which undergo …

Selenium Probes For The Detection Of Thioredoxin Reductase Activity, Tendai Joseph Mafireyi

Dissertations and Theses

The identification and quantification of proteins and enzymatic activity in living tissues frequently requires the use of invasive procedures such as biopsy. These techniques can inhibit measurements of protein levels in real-time, and the disruption of tissue can lead to the loss of important information concerning the spatial distribution and differential activities in various cell types. The use of small organic fluorescent probes that rely on activation or accumulation within a tissue embody robust methods of detection that address these issues. This dissertation describes the design, synthesis and evaluation of fluorescent probes that can detect the enzyme thioredoxin reductase (TrxR). …

Mechanistic Investigation Of Neuropeptide S-Nitrosylation By Nitric Oxide Moieties: A Kinetic And Thermodynamic Approach, Vusumuzi Leroy Sibanda

Dissertations and Theses

This dissertation focuses on providing quantitative insights regarding kinetic, thermodynamic and mechanistic parameters of neuropeptide S-nitrosylation by nitrous acid (HNO₂), peroxynitrite (ONOO^-) and S-nitroso-N-acetyl-D,L-penicillamine (SNAP) to produce S-nitrosothiols (SNOs). Peptide thiol stability and the formation of SNOs from neuropeptides; arginine vasopressin (AVP), somatostatin-14 (SST-14) and urotensin II (U-II) was studied. Investigations into the effects of temperature, copper chelators and pH on peptide thiol autoxidation show that AVP, SST-14 and U-II thiols have half-lives of 30, 44 and 28.2 mins respectively at physiologically relevant temperature and pH in the absence of metal chelators. Target peptide thiols were …

The Development And Application Of Instrumental Methods For The Identification Of Materials And Processes Used In The Manufacture Of Orotone, Hand-Colored Orotone, And Silvertone Photographs, Ivanny Jeannette Jácome-Valladares

Dissertations and Theses

Orotone photographs are positive photographic images on glass with a gold-colored metallic coating or backing. Although the materials and process used in the production of orotones have been previously documented, there is limited published scientific research on the subject. This study focused on expanding those published works by analyzing a greater number of photographs, including eleven orotones, four hand-colored orotones, two silvertones, and one uncoated orotone. The photographs, dating from the early to mid-20^th century, were from the University of Washington (UW) Libraries' collection, except for one orotone that was from the Portland Art Museum.

X-ray Fluorescence (XRF) spectroscopy, …

Tellurorhodamine Photocatalysts In Aerobic Oxidation Reactions: Development Of Synthetic Methods And Reaction Mechanisms, Irving D. Rettig

Dissertations and Theses

Aerobic oxidation photocatalysis involves the use of oxygen as an oxidant species, coupled to a light driven catalyst to achieve useful chemical transformations. Catalytic aerobic oxidation reactions can be defined as either oxidase-like, in which O₂ acts as an electron donor/acceptor but is not incorporated into the reaction products, or oxygenase-like where O₂ acts as an electron donor/acceptor and is incorporated into the reaction products. A multitude of inorganic catalysts have been developed that can achieve a wide scope of oxidase-like or oxygenase-like reactivity, however, it is rare for a catalyst to be capable of both. We report …

Investigations Into Size And Surface Control Of Silicon Nanocrystals For Improved Optical Properties, James Donald Barnes

Dissertations and Theses

The discovery of visible photoluminescence (PL) from nanocrystalline porous silicon in 1990 led to extensive research into the mechanisms of the emergent properties, and optimization of these properties, for use in applications. The widespread use of silicon nanoparticles (Si NPs) in commercial applications is currently limited by three main factors: 1) poor radiative recombination efficiency of the interband transition, 2) instability of the interband photoluminescence, and 3) a lack of scalable methods for producing Si NPs that are both highly crystalline and size monodisperse.

To address these limitations, this dissertation correlates changes in the photoluminescence properties of hydrogen passivated silicon …

Steady-State Transmembrane Water Exchange In Proliferating Cultures Of Saccharomyces Cerevisiae, Joseph O'Malley Armstrong

Dissertations and Theses

Cellular water exchange is often considered in terms of a change in volume, where a net flux of water moves across the cell membrane due to a change in osmotic pressure. Osmotic pressure can cause a cell to shrink or swell, however, rapid water exchange persists across the membrane even when the volume of the cell is constant. Steady-state transmembrane water exchange describes the exchange of water across the cell membranes which results in no net change in cell volume. This exchange is astonishingly rapid; the entire pool of intracellular water of a Saccharomyces cerevisiae cell may exchange 2-5 times …

Chemical Characterization Of Toxicologically Relevant Molecules In Cannabis Concentrates And Vaporizer Aerosols, Jiries Meehan-Atrash

Dissertations and Theses

Consumption of cannabis concentrates using the relatively novel non-combustion methods dabbing and vaping has steadily grown in popularity as cannabis legalization in North America has allowed increased access to sophisticated cannabis products and technology. In order to assess the safety of these products, it is necessary to gain a chemical understanding of the decomposition reactions that occur when the active ingredients are heated in the conditions seen when dabbing or vaping. This dissertation contains a manuscript that details efforts to structurally characterize a toxic cannabis concentrate adulterant, and three manuscripts that studied the chemical decomposition of the two primary cannabis …

Thermodynamics Of Ligand Binding And Global Structural Stability Of Human Serum Albumin, Matthew Walter Eskew

Dissertations and Theses

Protein structure is integral to its function. For the past 70 years differential scanning calorimetry has been used to measure protein structural stability. More recently it has been used to study macromolecular interactions. Interactions between proteins and ligands can manifest on differential scanning calorimetry melting curves or thermograms. Utilizing differential scanning calorimetry thermograms to detect or diagnose diseases has been a major goal in disease diagnostics. However, correlating specific ligand-protein interactions, as manifested in a thermogram, with a disease-specific plasma thermogram, has proven elusive.

Modified human serum albumin was utilized to develop a process to capture and retrieve ligands from …

Complex Fluid Dynamics: Chemo-Hydrodynamics Driven By Autocatalytic Reaction Fronts, Matthew Walter Eskew

Dissertations and Theses

Chemo-hydrodynamics generated from reaction-diffusion-convection processes of autocatalytic chemical systems are extensively studied for their applications in modeling complex systems. Compared to the more extensively studied autocatalytic systems, chlorite-tetrathionate and chlorite-trithionate, the chlorite-thiourea systems is relatively unexplored. Compared to the two previous systems, chlorite-thiourea has more straightforward chemical kinetics. To narrow the gap between chlorite-thiourea and the other systems a combination of experimental study and numerical simulation were employed to quantify this system.

Compared to established literature, experiments were performed at five orders of magnitude lower concentration of indicator, minimizing confounding effects of indicator on hydrodynamic motion. To accurately image the …

Comparison Of Calculated Normal Mode Molecular Vibrations With Experimental Gas-Phase Infrared Spectroscopy, Anila Renis Sutar

Dissertations and Theses

Computational vibrational spectroscopy serves as an important tool in the interpretation of experimental infrared (IR) spectra. Analysis of computational results provides a perspective over broader wavelength ranges and at higher precision. Although there are issues regarding accuracy, this can be approximated by using a scaling factor. High-resolution gas-phase FTIR spectroscopy at a resolution of 0.125 cm^-1 can partially resolve rovibrational transitions in the P, Q, and R bands and therefore identify fundamental frequencies with approximately 1 cm^-1 precision.

This research has compared high-resolution gas-phase FTIR absorption peaks to calculated vibrational frequencies. In the calculation of normal mode frequencies, …

Aryne-Guided C-H Functionalization Of Benzenoid Rings Using Diaryliodonium Salts, Aleksandra Nilova

Dissertations and Theses

The benzenoid core is a frequent and irreplaceable component of biologically active molecules. Structure function relationship of these compounds has been broadly analyzed and presented in numerous literature reports. Herein, we augmented existing knowledge by a broad analysis of the benzenoid substitution patterns in small molecule active pharmaceutical ingredients approved by the FDA. Our findings reveal a strong correlation that the most represented substitution patterns are those achieved via S_EAr. Despite the rapid development of methods to functionalize benzenoid rings, the lack of synthetic methodologies to access sterically and electronically unfavorable positions is highlighted. We sought to establish …