Physical Sciences and Mathematics Commons^™

Single-Variable Porous Nanomaterial Series From Polymer Structure-Directing Agents, Morgan Stefik

Faculty Publications

Block polymer structure-directing agents (SDA) enable the production of porous nanoscale materials. Most strategies rely upon polymer equilibration where diverse morphologies are realized in porous functional materials. This review details how solvent selectivity determines the polymer SDA behaviors, spanning from bulk-type to solution-type. Equilibrating behavior of either type, however, obscures nanostructure cause-and-effect since the resulting sample series convolve multiple spatial variations. Solution-type SDA behaviors include both dynamic and persistent micelles. Persistent micelle templates (PMT) use high solvent selectivity for kinetic entrapment. PMTs enable independent wall thickness control with demonstrated 2 Å precision alterations. Unimodal PMT pore size distributions have spanned …

From Persistent Radicals To Conductivity: A Structure Property Investigation In A Series Of Urea-Tethered Halogenated Triphenylamines, Muhammad Saddam Hossain

Theses and Dissertations

Triphenylamines (TPAs) are known to form persistent organic radicals either by chemical, electrochemical or photoinduced oxidation. Typically, fully para-substituted TPAs form stable radical cations while the radical cations in partially substituted systems quickly degrade. Herein, we study the effects of solid-state organization on a series of urea tethered halogenated TPAs 1 (X = H, Cl, Br, I) and compare their radical cation formation and persistence after UV-irradiation. These halogenated urea tethered TPAs were examined by single-crystal X-ray diffraction where their assembly was guided by threecentered urea hydrogen bonding interaction. As expected, all compounds form photogenerated radical cations in solution, but …

Investigations On The Surface Chemistry Of Colloidal Quantum Dots Towards Fluorescent Biological Probes, John Hardin Dunlap

Theses and Dissertations

Colloidal semiconductor quantum dots (QDs) have garnered significant interest as promising materials for biological applications due to their improved photostability and narrow, tunable photoluminescence properties compared to organic fluorophores. To facilitate their utility as fluorescent bioimaging probes, QDs must undergo post-synthetic modifications to exchange their native hydrophobic ligands from synthesis with hydrophilic ones that enable colloidal dispersions in aqueous environments. Many examples exist that demonstrate surface modifications for water-soluble QDs and their efficacy in biological systems, however, there is a need to develop a more thorough understanding of how hydrophilic ligands coordinate to QD surfaces in order to develop more …

Teaching An Old Dog New Tricks: Synthesis And Applications Of Novel Polybenzimidazole (Pbi) Membranes, Laura Ann Murdock

Theses and Dissertations

Polybenzimidazoles (PBIs) represent a class of performance polymers that display exceptional thermal and oxidative stability. For almost thirty years, PBI membranes have been investigated as promising candidates for next-generation alternative energy devices, including high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) and vanadium redox flow batteries (VRBs). Issues with the production of PBI membranes arise from their inherent low solubility in organic solvents. Thus, conventional approaches typically yield membranes that have limited molecular weight and generate significant waste in preparation, due to the large quantity of solvent required to dissolve PBIs for membrane casting.

Presented herein is the development of …

Investigating The Chemistry Of Harmful Algal Blooms And Microbial Communities In The Natural Environment, Samuel Patrick Putnam

Theses and Dissertations

Cyanobacteria has existed on the planet for over 3 billion years, and as technology, science, and industry have allowed us to shape our world, these changes have caused a proliferation of biomass. Higher carbon dioxide levels in the atmosphere, warmer temperatures, and rapid increases in the nutrient cycle have created excellent growing conditions for cyanobacteria, making them endemic in fresh waters throughout the world. The work in this dissertation was directed towards the secondary metabolites produced by cyanobacteria and other surrounding microbes and understanding their concentrations and release in natural systems. Analytical methods were developed for the extraction and quantification …

Enhancing Charge Carrier Mobility In Colloidal Quantum Dots For Technological Applications, Fiaz Ahmed

Theses and Dissertations

Colloidal quantum dots (QD) are promising semiconducting materials to engineer photovoltaic and optoelectronic devices due to tunable size-dependent absorption and emission properties. These materials are important as they don’t need complicated equipment and huge setup investment for industrial applications. If formulated into a kind of stable nano-ink, these QDs can be incorporated into devices using the most economical processing technologies, spray or roll to roll printing. More importantly, these are compatible with thin-film stacked devices and circuitry that can be formed on heat-sensitive and flexible substrates to make flexible wearable devices and sensors that are difficult to achieve with crystalline-based …

Polymeric Sorbents For Solid-Phase Extraction (Spe) Of Polar Analytes And Carbon Dioxide Capture, Ishwor Karki

Theses and Dissertations

The main topics of this dissertation are: 1) the study of hydrophilic-lipophilic balance (HLB) polymer monoliths for solid-phase extraction (SPE) applications, 2) molecularly imprinted polymers (MIPs) for capturing the CO2 gas and 3) the application of symmetry-adapted perturbation theory (SAPT) calculations to examine the origins of non-covalent interactions.

HLB polymers are popular sorbent materials in separation science. The Divinylbenzene-co-N-vinylpyrrolidone (DVB-co-NVP) polymer is one of the most widely used general-purpose HLB polymers. Despite the popularity of HLB polymer stationary phases, the studies of the adsorption properties of DVB-co-NVP have only been reported over a narrow …

Optimization And Application Of Electrochemical Probes For Neurotransmitter Detection, Colby E. Witt

Theses and Dissertations

The brain is a complex matrix that is difficult to study. Signaling molecules, neurotransmitters, are constantly being released and sequestered back into neurons within milliseconds to facilitate communication and normal function, a process called neurotransmission. There are few analytical techniques available to selectively probe such a dynamic system, and even fewer can detect these discrete changes in real-time. In order to make robust measurements in the brain you need speed, sensitivity, selectivity and small probe size, which are encompassed by fast-voltammetry with microelectrodes. Traditional fast-voltammetry at carbon fiber microelectrodes (fast-scan cyclic voltammetry (FSCV)) requires background subtraction to overcome the large …

Developing Covalent-Organic Frameworks For Protecting Against Radiation, Megan J. Francis

Senior Theses

This research focuses on the development of lightweight, thermostable dual-function materials for secondary radiation protection and sensing by the integration of hydrogen-rich aliphatic chains inside the porous matrix of covalent-organic frameworks (COFs). The main aims of this project are the synthesis of organic linkers for forming a robust porous COF, synthesizing the porous COF through a condensation reaction, the development of hydrogen-rich aliphatic chains, and integration of aliphatic chains into COFs through click chemistry. This manuscript outlines the methodology and development of a novel self-assembled crystalline, porous material engineered to combine the functions of a shield and sensitive dosimeter. The …

Characterization Of A Novel Fe-S Cluster Transfer Pathway Between Grx4 And Sufa In Escherichia Coli, Enis Sanchez

Theses and Dissertations

Biogenesis of iron-sulfur (Fe-S) clusters is an essential process in living organisms due to the critical role of Fe-S cluster proteins in a myriad of cellular functions. During the assembly of Fe-S clusters, multi-protein complexes are used to drive the mobilization and protection of reactive sulfur and iron intermediates, regulate assembly of various Fe-S clusters on an ATPase-dependent, multi-protein scaffold, and target nascent clusters to their downstream protein targets. In each of the Fe-S cluster biogenesis steps, specific protein-protein interactions (PPIs) are required for proper function of the assembly pathway. The target pathway is the sulfur formation (Suf) pathway for …

Fe-Catalyzed Sulfide Oxidation In Hydrothermal Plumes Is A Source Of Reactive Oxygen Species To The Ocean, Timothy J. Shaw, George W. Luther Iii, Richard Rosas, Véronique E. Oldham, Nicole R. Coffey, John L. Ferry, Dewamunnage M. C. Dias, Mustafa Yücel, Aubin Thibault De Chanvalon

Faculty Publications

Historically, the production of reactive oxygen species (ROS) in the ocean has been attributed to photochemical and biochemical reactions. However, hydrothermal vents emit globally significant inventories of reduced Fe and S species that should react rapidly with oxygen in bottom water and serve as a heretofore unmeasured source of ROS. Here, we show that the Fe-catalyzed oxidation of reduced sulfur species in hydrothermal vent plumes in the deep oceans supported the abiotic formation of ROS at concentrations 20 to 100 times higher than the average for photoproduced ROS in surface waters. ROS (measured as hydrogen peroxide) were determined in hydrothermal …

Small Studies, Big Decisions: The Role Of Pilot/Feasibility Studies In Incremental Science And Premature Scale-Up Of Behavioral Interventions, Michael William Beets, Lauren Von Klinggraeff, Robert G. Weaver, Bridget Ryan Armstrong, Sarah Burkart

Faculty Publications

Background: Careful consideration and planning are required to establish “sufficient” evidence to ensure an investment in a larger, more well-powered behavioral intervention trial is worthwhile. In the behavioral sciences, this process typically occurs where smaller-scale studies inform larger-scale trials. Believing that one can do the same things and expect the same outcomes in a larger-scale trial that were done in a smaller-scale preliminary study (i.e., pilot/feasibility) is wishful thinking, yet common practice. Starting small makes sense, but small studies come with big decisions that can influence the usefulness of the evidence designed to inform decisions about moving forward with a …

Creation Of A Cip Method For The Heat Exchangers At Rolls-Royce, Melanie Howe, Austin Williams, Caroline Dempsey, Bethany Fralick

Journal of the South Carolina Academy of Science

Rolls-Royce produces various engines which must be tested prior to their distribution to ensure a high-quality product. The manufacturing plant contains four test cells where the engines can be subjected to high levels of torque and extreme temperatures. A heat exchanger is necessary in this testing system and over time, unwanted waste accumulates on the system’s plates. The team is tasked with developing and implementing a system mounted on a mobile cart which can provide data to determine whether the plates need to be cleaned. For this cleaning system to work, it must fully saturate the heat exchanger in cleaning …

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

The Effect Of Poverty Levels And Minority Percentages On Lead Content In South Carolina Midlands School Drinking Water, Kathleen L. Barfield

Journal of the South Carolina Academy of Science

No abstract provided.

2021 Scas Annual Meeting Program And Bulletin

Journal of the South Carolina Academy of Science

No abstract provided.

Exploration Of Vase As An Extraction Method For Emerging Disinfection By-Products And Acidic Methanol As A Safe And Effective Derivatization Method For Haloacids, Madison Leigh Kilpatrick

Theses and Dissertations

This project aims to create an environmentally friendly, robust, and efficient extraction and preconcentration method in both the detection and quantification of various disinfection by-products (DBPs). Vacuum assisted sorbent extraction (VASE) is a newly developed method in the extraction of both volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). This extraction method is paired with a Thermo Scientific TSQ Quantum Triple Quadrupole GC-MS system for the quantification of DBPs. VASE outperforms current DBP extraction methods, with liquid-liquid extraction (LLE) being the most used alternative, because of its minimal use of solvent, high level of automation, and over-all ease of …

Alkyne Cyclization Involving A Zwitterionic Hexaruthenium Carbido Carbonyl Complex And The Synthesis Of The First-Nitrido Heterometallic Carbonyl Cluster Complexes, Nutan Damodhar Wakdikar

Theses and Dissertations

Chapter 1 introduces two related topics with the primary focus on the background of zwitterions and the conceptual understanding of a metal-complexed zwitterion. It also discusses the potential of a metal-complexed zwitterion for a carbon-carbon bond formation reaction. Synthesis of the metal carbonyl cluster, Ru6(µ6-C)(µ-CO)(CO)16, is also discussed in detail. Then, the background with the importance of heterometallic cluster complexes is discussed with the help of various examples used for catalysis.

The reaction of hexaruthenium carbido carbonyl cluster, Ru6(µ6-C)(µ-CO)(CO)16, with C2H2 and Me3NO yielding first examples of two new zwitterionic complexes, Ru6C(CO)15(μ−η2−C2H2NMe3), 2.2, and Ru6C(CO)14(μ3−η4−C4H4NMe3), 2.3, are presented in Chapter …

Characterization Of A High Affinity Glutathione Transporter And Its Impact On Glutathione Depleted Saccharomyces Cerevisiae, Tirthankar Bandyopadhyay

Theses and Dissertations

Thiol-disulfide redox homeostasis is integral for maintaining the redox status of proteins and other thiol-containing molecules within the cell. Among the many antioxidants and detoxifying enzymes and small peptides, glutathione (GSH) has proven to be critical for the preservation of function and structural integrity of the cell due to its functionality in areas like oxidative protein folding, thiol redox control, reactive oxygen species (ROS) and xenobiotics removal as well as iron regulation and Fe-S cluster biogenesis. Therefore, our studies are aimed at elucidating the factors that control GSH trafficking and metabolism in the model eukaryote Saccharomyces cerevisiae (baker’s yeast). Using …

Ahr Expression On Rorc-Expressing Immune Cells Is Essential For I3c-Mediated Protection Against Colitis, Michal C. Williams

Senior Theses

Colitis is an inflammatory bowel disorder (IBD) whose etiology is attributed to modification in the luminal microbiota and dysregulation in the immune response. Indole is a signaling molecule which is naturally produced by gut luminal microbiota. Indole-3- carbinol (I3C) is a compound commonly found in vegetables and a ligand for the aryl hydrocarbon receptor (AhR). Previous studies have detected decreased expression and activation on the AhR receptor in colitis patients, thought to possibly alter gut microbiota metabolism, subsequently promoting colitis. 1 AhR, expressed in a variety of immune and epithelial cells, contributes to gut homeostasis by affecting vital mediators such …

Plasmonic Metallic And Semiconductor Nanomaterials, Mengqi Sun

Theses and Dissertations

The earliest account of localized surface plasmon resonance (LSPR) has to date back to the ancient age of Rome in 400 A.D. The famous glass of Lycurgus cup told the story of unique light-and-matter interaction at the nanoscale that confines the electromagnetic field resonance at its surface and therefore allows LSPR feature to noticeably arise. The conventional metallic LSPR nanomaterials, like Au and Ag nanoparticles attract constant attentions due to their synthetic simplicity, chemical robustness, and visible spectral response. Its ability to generate sensitive dielectric sensing of the surroundings, strong electromagnetic field and active charge carriers upon optical excitation triggered …

Characterization Of Ph – Responsive Nanocage Based On The Ferritin Iron Storage Protein, Satyam Singh

Theses and Dissertations

The iron-storage protein ferritin (Ftn) assembles into a protein cage structure with 24 subunits and octahedral (4-fold, 3-fold, 2-fold) symmetry. Each monomeric subunit contains a robust four-helix bundle fold. The fully assembled Ftn structure has a high degree of thermal stability (up to 100°C), a mono dispersed size (12 nm in diameter), and a large central cavity (7-8 nm in diameter). The central cavity stores ferric iron in phylogenetically diverse group of organisms, including humans. The central cavity has been used for encapsulation of cargoes such as other metals, contrast agents for imaging, small molecule drugs for therapy, …

Colloidal Semiconductor Quantum Dots: Solution Processing And Heterostructure-Based Optoelectronics, Mathew L. Kelley

Theses and Dissertations

Colloidal semiconductor quantum dots (QDs) are attractive candidates for high-efficiency solar cells and uncooled multiplexed photodetectors due to their favorable characteristics including large absorption cross-sections, size-tunable bandgap energies spanning the ultraviolet (UV) to short wave infrared, and solution processability. These QD-based optoelectronic devices operate on the basis of efficient photogenerated charge migration within QD solids and charge separation and recombination at electrical junctions, underscoring the need for (1) processing strategies that facilitate charge transport and (2) characterization techniques that robustly interrogate charge separation at QD interfaces. Here, my work on the post-synthetic processing and surface modifications of several semiconductor QDs, …

Developing And Understanding Catalysts For Organic Synthesis, Shelby Dickerson

Theses and Dissertations

Organic synthesis relies on improving catalyst designs and understanding reaction mechanisms for the advancement of the field. This dissertation will describe projects in both of these areas. First it will cover new photocatalysts in the aim of maintaining reactivity while increasing solubility in less polar solvents, and second understanding the importance of intermolecular interactions between new nucleophilic catalysts and substrates.

Photocatalysis has become a major focus as a sustainable pathway for chemical reactions with visible light photocatalysts performing a large range of reactions such as redox reactions, cyclization reactions, and energy transfer reactions. Chapter 1 will discuss classes of organic …

Free Three-Dimensional Carborane Carbanions, H.D.A. Zzzchathumal Jayaweera, Md. Mamdudur Rahman, Perry J. Pellechia, Mark D. Smith, Dmitry V. Peryshkov

Faculty Publications

Carbon atom functionalization via generation of carbanions is the cornerstone of carborane chemistry. In this work, we report the synthesis and structural characterization of free ortho-carboranyl [C₂B₁₀H₁₁]⁻, a three-dimensional inorganic analog of the elusive phenyl anion that features a “naked” carbanion center. The first example of a stable, discrete C(H)-deprotonated carborane anion was isolated as a completely separated ion pair with a crown ether-encapsulated potassium cation. An analogous approach led to the isolation and structural characterization of a doubly deprotonated 1,1′-bis(o-carborane) anion [C₂B₁₀H₁₀] …

Tailored Porous Carbons Enabled By Persistent Micelles With Glassy Cores, Eric R. Williams, Paige L. Mcmahon, Joseph E. Reynolds Iii, Jonathan L. Snider, Vitalie Stavila, Mark Allendorf, Morgan Stefik

Faculty Publications

Porous nanoscale carbonaceous materials are widely employed for catalysis, separations, and electrochemical devices where device performance often relies upon specific and well-defined regular feature sizes. The use of block polymers as templates has enabled affordable and scalable production of diverse porous carbons. However, popular carbon preparations use equilibrating micelles which can change dimensions in response to the processing environment. Thus, polymer methods have not yet demonstrated carbon nanomaterials with constant average template diameter and tailored wall thickness. In contrast, persistent micelle templates (PMTs) use kinetic control to preserve constant micelle template diameters, and thus PMT has enabled constant pore diameter …

Host–Guest Interactions In A Metal–Organic Framework Isoreticular Series For Molecular Photocatalytic Co2 Reduction, Philip M. Stanley, Johanna Haimerl, Christopher Thomas, Alexander Urstoeger, Michael Schuster Prof. Dr., Natalia B. Shustova Prof. Dr., Angela Casini Prof. Dr., Bernhard Rieger Prof. Dr., Julien Warnan Dr., Roland A. Fischer Prof. Dr.

Faculty Publications

A strategy to improve homogeneous molecular catalyst stability, efficiency, and selectivity is the immobilization on supporting surfaces or within host matrices. Herein, we examine the co-immobilization of a CO2 reduction catalyst [ReBr(CO)3(4,4′-dcbpy)] and a photosensitizer [Ru(bpy)2(5,5′-dcbpy)]Cl2 using the isoreticular series of metal–organic frameworks (MOFs) UiO-66, -67, and -68. Specific host pore size choice enables distinct catalyst and photosensitizer spatial location—either at the outer MOF particle surface or inside the MOF cavities—affecting catalyst stability, electronic communication between reaction center and photosensitizer, and consequently the apparent catalytic rates. These results allow for a rational understanding of an optimized supramolecular layout of catalyst, …

Beyond Structural Motifs: The Frontier Of Actinide-Containing Metal–Organic Frameworks, Corey R. Martin, Gabrielle A. Leith, Natalia B. Shustova Prof. Dr.

Faculty Publications

In this perspective, we feature recent advances in the field of actinide-containing metal–organic frameworks (An-MOFs) with a main focus on their electronic, catalytic, photophysical, and sorption properties. This discussion deviates from a strictly crystallographic analysis of An-MOFs, reported in several reviews, or synthesis of novel structural motifs, and instead delves into the remarkable potential of An-MOFs for evolving the nuclear waste administration sector. Currently, the An-MOF field is dominated by thorium- and uranium-containing structures, with only a few reports on transuranic frameworks. However, some of the reported properties in the field of An-MOFs foreshadow potential implementation of these materials and …

Beyond Structural Motifs: The Frontier Of Actinide-Containing Metal–Organic Frameworks, Corey R. Martin, Gabrielle A. Leith, Natalia B. Shustova

Faculty Publications

In this perspective, we feature recent advances in the field of actinide-containing metal-organic frameworks (An-MOFs) with a main focus on their electronic, catalytic, photophysical, and sorption properties. This discussion deviates from a strictly crystallographic analysis of An-MOFs, reported in several reviews, or synthesis of novel structural motifs, and instead delves into the remarkable potential of An-MOFs for evolving the nuclear waste administration sector. Currently, the An-MOF field is dominated by thorium- and uranium-containing structures, with only a few reports on transuranic frameworks. However, some of the reported properties in the field of An-MOFs foreshadow potential implementation of these materials and …

The Supercam Instrument Suite On The Mars 2020 Rover: Science Objectives And Mast-Unit Description, S. Maurice, R. C. Wiens, P. Bernardi, P. Caïs, S. Robinson, T. Nelson, O. Gasnault, J. -M. Reess, M. Deleuze, F. Rull, J. -A. Manrique, S. Abbaki, R. B. Anderson, Y. André, Stanley M. Angel, G. Arana, T. Battault, P. Beck, K. Benzerara, S. Bernard, Et. Al.

Faculty Publications

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2–7 m, while providing data at sub-mm to mm scales. We report …