Physical Sciences and Mathematics Commons^™

Synthesis Of Block Copolymer Additives For Examining Phase Morphology And Improving Mechanical Properties Of Thermoplastics Elastomers., Bishal Upadhyay

Masters Theses

Polystyrene-block-poly(1,4-butaidene)-block-polystyrene (PS-PB-PS) triblock copolymers are one of the most widely studied thermoplastic elastomers (TPEs) due to their ease of synthesis, non-polar nature, and commercial applicability. Like many block copolymers, incompatibility between PS and PB causes these TPEs to undergo microphase segregation. Many studies have examined the mechanical properties of blends of TPEs and PS homopolymer additives. However, there have been few studies focused on understanding the morphology and mechanical properties of blends of TPEs and copolymer additives with different architectures. Herein, I describe the synthesis of linear and graft copolymer additives based on the random copolymers poly(methyl methacrylate-random-cyclohexyl methacrylate) (PrC). …

The Influence Of Ion-Ion Correlations On Conductivity In Concentrated Ionic Systems, Md Dipu Ahmed

Masters Theses

This study delves into the fascinating realm of concentrated ionic systems, such as ionic liquids, superionic materials, organic ionic plastic crystals, and polyelectrolytes, which hold immense potential for energy storage applications. The focus is on understanding the intricate role of ionic correlations in shaping their ionic conductivity behavior. These correlations can either boost or impede conductivity, yet their underlying mechanisms remain elusive. Through extensive investigation of various materials, including ionic liquids with differing anionic masses, pure organic ionic plastic crystals, and doped systems, this research employs advanced techniques like dielectric spectroscopy and innovative momentum conservation models to quantify these correlations. …

Machine Learning Modeling Of Polymer Coating Formulations: Benchmark Of Feature Representation Schemes, Nelson I. Evbarunegbe

Masters Theses

Polymer coatings offer a wide range of benefits across various industries, playing a crucial role in product protection and extension of shelf life. However, formulating them can be a non-trivial task given the multitude of variables and factors involved in the production process, rendering it a complex, high-dimensional problem. To tackle this problem, machine learning (ML) has emerged as a promising tool, showing considerable potential in enhancing various polymer and chemistry-based applications, particularly those dealing with high dimensional complexities.

Our research aims to develop a physics-guided ML approach to facilitate the formulations of polymer coatings. As the first step, this …

Redox-Active Polymerization Catalysts And Their Applications, Nicholas M. Shawver

Masters Theses

Traditional catalyst systems are reliable means to produce polymers with well-defined architectures and thermomechanical properties; however, they are often limited by a narrow monomer scope and their ability access few, if any, advanced polymer architectures. To address this limitation, a new class of catalysts have recently emerged that feature redox-active moieties that may access advanced architectures through catalyst electronic modulation that arises from redox events occurring on the ligand scaffold or at the active metal center itself. For example, researchers have explored the ability of redox-active catalysts to impart “on-off” kinetic control during ring-opening polymerizations and their ability to access …

Expression And Purification Of Polyketide Synthase Domains To Investigate Protein-Protein Interactions In Polyketide Biosynthetic Pathways, Mujeeb Adeyinka Wakeel

Masters Theses

Polyketide synthases (PKSs) are multienzyme proteins catalyzing the production of the polyketide class of natural products with vast structural diversity. Type II PKSs catalyze polyketide biosynthesis using discrete (standalone) enzymes (domains), while type I PKSs use covalently linked enzymes arranged in a module to catalyze polyketide production. It is hypothesized that type II PKSs are the precursors to type I PKSs, proposing that the genes encoding individual discrete enzymes in type II PKSs fused to give the multienzyme modules of type I PKSs. We reasoned that the intramolecular-like reactions occurring in type I PKS modules might be a driving force …

Copper-Indazolate Nanojars: Synthesis And Characterization, Nicholas Alexander Rudell

Masters Theses

The field of synthetic supramolecular chemistry has exploded since the first syntheses of crown ethers by Charles Pedersen in the 1960s, leading to further development in the area of macrocycles and incorporation into a vast array of metal-organic structures. Supramolecular chemistry came to the forefront of science with the 1987 Nobel Prize in Chemistry, awarded jointly to Donald J. Cram, Jean-Marie Lehn, and Charles Pedersen “for their development and use of molecules with structure-specific interactions of high selectivity.”

Nanojars are supramolecular metal-organic complexes with a high affinity for hydrophilic anions and can efficiently transfer such anions from water into organic …

Development And Study Of Small Database For The Activation Of Nitrous Oxide Towards Formation Of Iron(Iv)-Oxo Species, Tobias Barthalomew Robertson

Masters Theses

Nitrous oxide (N₂O) can undergo an oxygen atom transfer (OAT) reaction resulting in inert nitrogen gas (N₂O) while transferring an oxygen atom to a molecular complex or material. This process is of catalytic importance since this OAT reaction can be leveraged to form iron(IV)-oxo sites, which are known to be catalytic intermediates. Here, an investigation of the ligand field effects on primarily iron(II) complexes for the formation of iron(IV)-oxo sites with nitrous oxide as the oxidant is reported. An initial database of sixty-four molecular complexes with ligand environments varying in field strength and coordination geometry was …

Understanding The Polymerization Of Ethyl Cyanoacrylate In The Superglue Fuming Of Latent Prints To Optimize Print Retrieval, Leondra Shawntae Lawson

Masters Theses

The cyanoacrylate fuming method (CFM) is a widespread process used in forensics to make latent prints visible for detection, acquisition, and analysis. CFM is governed by the reaction of ethyl cyanoacrylate (ECA) with biological components in fingerprints, which serve as initiators for this anionic polymerization. CFM is not a well-controlled polymerization and there are different outcomes that may result from lower temperature, one of which fits the generalization of creating more ion-pair initiators. Another effect could be minimizing termination through suppressing side reactions. Alternatively, when paired with humidity, lower temperatures may cause surface condensation, decreasing the quality of the print. …

Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer

Masters Theses

Cover crops provide multiple environmental benefits that improve both soil and water quality; however, farmers only utilize them on approximately 5% of harvested U.S. cropland. Low adoption rates are attributed to yield impact concerns, seed and planting costs, and lack of advocacy. This study, which began in October 2019, assessed the effects of nitrogen rate and cover crop diversity on weed biomass, soil coverage, in-situ residue decomposition, soil nitrogen and phosphorus availability, and cash crop yield to better understand the costs and benefits of cover crop adoption at two locations in Tennessee (Milan and Spring Hill). Treatments were replicated 4 …

Synthesis And Characterization Of 2,6-Diisopropylphenoxy Tetrapyrazinoporphyrazines As Potential Molecular Qubits, Benjamin Marx

Masters Theses

This thesis reports the synthesis of metal-free and metal-containing phthalocyanine derivatives using methods typical for that class of functional dyes. A mixture of the target compounds prepared here, one paramagnetic and one diamagnetic tetrapyrazinoporphyrazine, will be tested for their potential use in spintronics – the application of spin-active species in molecular electronics. Phthalocyanines and their derivatives are well-known for their ease of preparation and tunability; they have been utilized as sensitizers for photodynamic therapy of cancer and solar cells, as well as in catalysis and chemical sensing. Tetrapyrazinoporphyrazine complexes are compared with the parent phthalocyanine as their chemistry is similar …

Kinetic And Structural Characterization Of Pseudooxynicotine Amine Oxidase From Pseudomonas Putida S16, Vishakha Choudhary

Masters Theses

Our laboratory has previously shown that nicotine oxidoreductase (NicA2), a member of the flavin-containing amine oxidase family, uses a cytochrome c protein (CycN) as its electron acceptor rather than characteristically accepted molecular oxygen. Within the Pseudomonas putida S16 genome, the nicA2 gene forms an operon with cycN and pseudooxynicotine amine oxidase (pnao), another flavin containing amine oxidase enzyme. The first two steps in the nicotine catabolism pathway are catabolized by NicA2 and Pnao. Through redox chemistry, NicA2 converts nicotine to pseudooxynicotine and Pnao converts pseudooxynicotine to 3-succinoylsemialdehyde-pyridine. In this thesis, we characterize the kinetic and structural properties of …

Chromatographic Dynamic Chemisorption, Shreya Thakkar

Masters Theses

Reaction rates of catalytic cycles over supported metal catalysts are normalized by the exposed metal atoms on the catalyst surface, reported as site time yields which provide a rigorous standard to compare distinct metal surfaces. Defined as the fraction of exposed metal surface atoms to the total number of metal atoms, it is important to measure the dispersion of supported metal catalysts to report standardized rates for kinetic investigations. Multiple characterization techniques such as electron microscopy, spectroscopy and chemisorption are exploited for catalyst dispersion measurements. While effective, electron microscopy and spectroscopy are not readily accessible due to cost and maintenance …

Pd-Based Photocatalysts For Heck C-C Cross-Coupling Reactions, Suha Ali Alshehri

Masters Theses

Heck C-C cross-coupling reaction has been widely employed in synthetic organic chemistry because of its high efficiency and simplicity, however the conventional Heck C-C cross-coupling reaction conditions involve the use of an expensive toxicant phosphine-ligated palladium complexes, and high temperature. To address these drawbacks, a highly efficient, homogeneous photocatalyst based on BODIPY for the Heck C-C cross-coupling reactions of aryl iodide and methyl acrylate in DMF solvent under inert conditions has been developed. The 4-Py-BDP-Pd, 3-Py-BDP-Pd and, 2-Py-BOD-Pd catalysts were synthesized and purified using column chromatography. The optical properties of products and intermediates were studied by UV/vis absorption and fluorescence …

Designing Polymer Materials For Improved Additive Manufacturing, Kaizhong Guan

Masters Theses

Currently, two of the most used additive manufacturing methods for polymers are selective laser sintering (SLS) and fused filament fabrication (FFF). Although at high market size, they both have imperfections. The materials for SLS are limited and the objects manufactured by FFF existing anisotropic behavior. Targeting on these drawbacks, this thesis has proposed a novel method to prepare polypropylene (PP) microsphere which is suitable for SLS with low cost and scalable potential; and a novel material with polycarbonate as matrix that has shown a decrease in anisotropy after FFF printing.

The PP microsphere in this thesis was prepared via liquid-liquid …

Influence Of Physical Variability Of Highly Weathered Sedimentary Rock On Nitrate In Area 3 Of The Enigma Field Research Site At Y-12, Erin Kelly

Masters Theses

Uranium processing and waste storage in unlined waste ponds leached contaminants into the groundwater at Y-12, Oak Ridge, Tennessee, from the 1950s to 1980s. Groundwater wells near the S-3 ponds have had the highest nitrate concentrations of groundwater anywhere in the world (>10,000 mg/L). For reference, the maximum contaminant level for nitrate in drinking water set by the U.S. Environmental Protection Agency is 10 mg/L. Since 2012, the ENIGMA (Ecosystems and Networks Integrated with Genes and Molecular Assemblies) group has been characterizing, monitoring, and conducting field experiments to understand the interactions between contaminants, microbes, and the subsurface. The goals …

Dissolved Organic Carbon And The Potential Role To Stream Acidity In The Great Smoky Mountains National Park, Jason R. Brown

Masters Theses

A substantial societal shift towards environmental awareness has focused research efforts on the impacts of pollution on natural landscapes. Improvements to pollutant regulations and technology have resulted in sizeable reductions of atmospheric deposition of anthropogenic acids, especially nitrates and sulfates, which has altered the role of these ions in the environment. As such, understandings of environmental chemistry dynamics have required regular updating.

Through the National Park Service Vital Signs monitoring program, increases in precipitation pH observed in Great Smoky Mountains National Park (GRSM) has been attributed to the reduction of inorganic acid concentrations. Unfortunately, these improvements have not been uniformly …

Development Of High Throughput Assays For Identification And Evaluation Of Small Molecule Inhibitors Of Microrna-31 Expression, Jackline A. Onyango

Masters Theses

Dysregulated expression of miRNAs has been linked to numerous cancers. On the other hand, miRNAs are potential drug targets due to the ability of their precursor molecules to fold into ligand binding structures. Small-molecule modulators of miRNAs offers opportunity for the development of new therapeutic agents and tools to further probe the mechanisms of miRNA functions. To facilitate the identification of miRNA modulators, the appropriate screening systems are needed, which would be adaptable for high-throughput applications, and allow for quantitative measurements. In this text, we present a molecular beacon-based assay to identify molecules that inhibit miRNA-31 processing by Dicer and …

Application Of Titrations For Verification Of Small Molecule Interaction In Relation To Amidoximated Fibers For Uranium Extraction From Seawater, Kc Michael Mote

Masters Theses

Nuclear energy is a promising substitute for fossil fuels due to possessing low carbon emissions and providing scalable base-load power. However, one major drawback of using nuclear fuel as an energy source is that it needs a steady source of uranium. While the most economical method of obtaining uranium is through conventional terrestrial mining of the ore uranite, mining uranium ores is both harmful to the environment and limited by the terrestrial uranium supply, which is estimated at only 100 more years. However, more than 1000× more uranium is dissolved in seawater than is reasonably inferred and assured in terrestrial …

Synthesis And Characterization Of A Two Station Starburst Pseudorotaxane, Janaka Prasad Kaviraj Kavikarage

Masters Theses

Mechanically interlocked molecules (MIMs) are arranged with mechanical bonds. These molecules cannot be separated without breaking the required covalent bonds. There are different kinds of MIMs, such as rotaxanes, catenanes, suitanes, borromean rings, and molecular knots. These MIMs are stabilized by non-covalent interactions such as hydrogen bonds, π-π stacking, and ion-dipole interactions. Dialkylammonium ions, bis(pyridinium)ethane dications, viologen species, and naphthalene diimide π-deficient groups are typical examples of recognition motifs for crown ethers.

In the research described here, we synthesized a new axle, based on a combination of benzobis(imidazolium) (BBI) and viologen species. The axle contains two recognition sites: one is …

Metal Complexes Of Bis(Pyrazolyl)Methane-Based Ditopic Ligands, Pubudu Nuwan Perera Hapuarachchige

Masters Theses

No abstract provided.

A Novel Palladium Bodipy Photocatalyst For Sonogashira Carbon-Carbon Cross-Coupling, Prahadeesh Nagaretnam

Masters Theses

No abstract provided.

Synthesis Of Well-Defined Binary Mixed Brushes On 20 Nm Silica Nanoparticles And Asymmetrically End- Functionalized Semicrystalline Poly(Ε-Caprolactone)S, Andrew J. Chancellor

Masters Theses

Well-defined polymers and polymer brushes play an important role in the understanding of their behavior under various conditions and in the fabrication of nanostructured functional materials. This Master’s thesis work focuses the synthesis of two well-defined systems: binary mixed homopolymer brushes grafted on 20 nm silica nanoparticles (NPs) for understanding their microphase separation behavior and asymmetrically end-functionalized semicrystalline poly(- caprolactone) polymers for use in the fabrication of multicomponent polymer brushes on flat substrates with various architectures. While theoretical and simulation studies have revealed intriguing morphologies of mixed homopolymer brushes grafted on nanospheres with a size similar to those of grafted …

Utilization Of Raman Spectroscopic Techniques For Forensic Science Applications, Alyssa Rose Daniel

Masters Theses

In the field of forensic science, it is important to have reliable, accurate, and nondestructive testing methods for evidence collection and testing. Current methods, such as gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC), are destructive to evidence and require lengthy sample preparation. Because of its nondestructive nature, specificity, and portability, Raman spectroscopy has been increasingly improving forensic science. The goal of this work is to expand on the growing pool of knowledge of forensics related Raman applications.

One problem that has plagued forensic scientists for years is how to accurately identify the time since death, or post-mortem interval. …

Synthesis And Biological Evaluation Of Azide- Tagged Biomimetic Probes For Global Labeling Of The Saccharomyces Cerevisiae Glycerolipidome, Matthew R. Johnson

Masters Theses

Lipid metabolism is an extremely complex, interconnected process that, when dysregulated, is strongly linked to cellular disease states including cancer. Study of these metabolic processes is complicated by the characteristic intricacy of these systems; nonetheless, it is achievable through metabolic labeling. Visualization of biosynthesis is an advantage offered by metabolic labeling through the incorporation of fluorescent tags. In this technique, synthetic probes bearing a clickable tag such as azide are fed into live cells where they are directly incorporated using the native enzymatic and cellular processes to metabolically label lipid products. These labeled lipid products are capable of being studied …

Sustained Release Of Persulfate And Iron(Ii) Ions From Inert Inorganic Materials For Groundwater Remediation, Peter Pham

Masters Theses

Contamination of groundwater, initiated from years of human negligence, continues to persist despite major advancements in water remediation technologies. The generated groundwater plumes can continuously replenish contaminants such as dense nonaqueous phase liquids (DNAPLs) through the aid of slow-moving water. Thus, long-term treatment of this flow system has proven to be problematic. A selection of sophisticated sustained diffusion technologies is needed to help prevent further damage to this prominent freshwater source.

Here, a novel in-situ chemical oxidation (ISCO) method was designed to incorporate persulfate into silica mediums such as zeolite, diatom, and silica flour for the treatment of groundwater contaminants …

Investigating The Effects Of Tethered, Axial Lewis Base Coordination On Rhodium(Ii) Paddlewheel Complexes, William A. Sheffield

Masters Theses

Dirhodium(II) paddlewheel complexes are highly renowned for their use in diazo decomposition to form a metallic-carbenoid species. This species has been used for a diverse range of chemical transformations including cyclopropanation, cycloproprenation, C-H functionalization, and X-H (Si, S, O, N) insertion reactions. Modulation of these catalysts traditionally involve the exchange of bridging ligands which have profound effects on the catalyst’s reactivity, chemo, and enantioselectivity. Recent interest has turned towards to modifying the axial sites present in the complex as an additional means of modulating catalytic activity. These sites normally serve as the active site of the catalyst, but coordination of …

Assessing The Robustness And Versatility Of Nanojars For Anion Binding, Mia Lily Ann Jawor

Masters Theses

Supramolecular chemistry is a field in chemistry that focuses on intermolecular bonds in a “host-guest complex” or supramolecular assemblies. Nanojars are supramolecular assemblies of the formula [anion⊂{Cu(μ-OH)(μ-pz)}_n] (n = 27‒33) which incarcerate kosmotropic anions, such as carbonate (CO₃^2‒), sulfate (SO₄^2‒) and hydrogen phosphate (HPO₄^2‒). Nanojars consist of three [Cu(μ-OH)(μ-pz)]_x (x = 6‒14, except 11) rings that are assembled similarly to Matryoshka dolls, where the top and bottom rings act as guests for the central ring. The larger central ring is bound to the two smaller rings by multiple …

An Analysis Of Factors Influencing Chemistry Students’ Choice Of Major And Career, Jennifer Marie Ribble

Masters Theses

In recent years there has been a push to increase the number of STEM graduates in the United States in order for the nation to retain its position as a global leader in the sciences. If educators are to address recruitment and attrition issues in STEM fields it is important to understand student perspectives related to choosing both a major and a career in chemistry. The present study explores the decision-making process students utilize to choose chemistry as a major and as a career, their perception of what careers are available to someone with a degree in chemistry and what …

Synthesis And Characterization Of Starburst Pseudorotaxanes And Their Metallic Derivatives, Shalini D. Kadinappulige

Masters Theses

Mechanically Interlocked Molecules (MIMs) are interlocked molecular architectures, characterized by the fact that they are linked through a mechanical bond. Catenanes, rotaxanes, molecular knots, and Borromean rings are typical examples for these molecules. Since MIMs are not connected by covalent bonds, hydrogen bonding, π- π stacking, and/or electrostatic interactions help bring the components together. Dialkyl-ammonium centers, bis(pyridinium)ethane dications, viologen species, and naphthalenediimide π-deficient groups are well known as recognition motifs for crown ethers. In the research described here, we have synthesized several pseudorotaxanes and their tricyclohexyltin metallic derivatives, based on benzobis(imidazolium) (BBI) salts as axles, in combination with the 15DN38C10 …

Design, Synthesis, And Characterization Of Chemical Tools To Study Peroxisomal Import, Jhalak N. Timilsena

Masters Theses

Peroxisomes are dynamic and interconnected single lipid membrane bound organelles found in the eukaryotic cells which are involved in various biochemical processes including the b-oxidation of very long chain and branched chain fatty acids, metabolism of reactive oxygen and nitrogen species, and reduction of hydrogen peroxide among others. These organelles are known to host numerous proteins and enzymes depending on the cellular environment. All of the proteins needed in the peroxisomes are encoded in the nucleus and synthesized in the cytosol which are then transported to the peroxisomes with the help of a sophisticated protein-transport machinery. Pex5 is one of …