Chemistry Commons^™

Application Of X-Ray Grating Interferometry To Polymer/Flame Retardant Blends In Additive Manufacturing, Omoefe Joy Kio

LSU Doctoral Dissertations

X-ray grating interferometry is a nondestructive tool for visualizing the internal structures of samples. Image contrast can be generated from the absorption of X-rays, the change in phase of the beam and small-angle X-ray scattering (dark-field). The attenuation and differential phase data obtained complement each other to give the internal composition of a material and large-scale structural information. The dark-field signal reveals sub-pixel structural detail usually invisible to the attenuation and phase probe, with the potential to highlight size distribution detail in a fashion faster than conventional small-angle scattering techniques. This work applies X-ray grating interferometry to the study of …

Synthesis, Characterization And Crystal Growth Of I2-Ii-Iv-Vi4 And I4-Ii-Iv2-Vi7 Diamond-Like Semiconductors With Potential In Ir-Nlo Applications, Jennifer Glenn

Electronic Theses and Dissertations

In this dissertation, several new and existing diamond-like semiconductors (DLSs) were synthesized and investigated for their potential in infrared nonlinear optical (IR-NLO) applications. In Chapter 2 growth of large single crystals of Li₂MnGeS₄ was carried out using iodine vapor transport and a newly created graphite-tube containment system. This crystallization method produced sizable single crystals on the scale of 2x1x1 mm³, that were used to determine the material’s magnetic properties. Magnetization data indicate that the compound is antiferromagnetic with a Néel temperature of 10 K and an effective magnetic moment of 5.6 /f.u.. The specific heat …

Nontraditional Hydrogen Bonding In Asymmetric Lewis Acid Catalysis, Brandon Vernier

Electronic Theses and Dissertations

In the field of asymmetric induction, there is a shift from the synthesis of reaction

specific chiral auxiliaries towards a broader mechanistic approach. Our approach is to

develop a theory of asymmetric catalyst design from first principles. The Diels-Alder

reaction of 2-methacrolein and 1,3-cyclopentadiene in the presence of 15 mole % lmenthoxy

aluminum dichloride, reported by Koga, achieved the (S)-exo-Diels-Alder

cycloadduct with 72% ee (0% ee Endo for acrolein). The dramatic change from 72% to 0%

ee is a significant fact that has been overlooked in practical organic synthesis.

In the first phase of this work, the conformational landscape of …

Lanthanum-Based Perovskites As An Effective Electrocatalyst For Water Splitting And Energy Storage Applications, Xavier Martinez

Electronic Theses & Dissertations

Recent changes in global weather patterns have accented the need a shift from fossil fuels to a cleaner energy option. As part of an overall plan, hydrogen production for fuel cells offer substantial power without carbon emissions. Overall water splitting, with the aid of a low cost electrocatalyst could prove to be an abundant green fuel source. Utilizing readily available transition metals, three perovskite nanostructures were studied as a multifunctional material for hydrogen production as well as an energy storage material. LaCoO₃ (LCO), LaFeO₃ (LFO)_, and LaMnO₃ (LMO) were synthesized and characterized by X-ray diffraction (XRD) …

Intercomparison Of Small Unmanned Aircraft System (Suas) Measurements For Atmospheric Science During The Lapse-Rate Campaign, Lindsay Barbieri, Stephan T. Kral, Sean C. C. Bailey, Amy E. Frazier, Jamey D. Jacob, Joachim Reuder, David Brus, Phillip B. Chilson, Christopher Crick, Carrick Detweiler, Abhiram Doddi, Jack Elston, Hosein Foroutan, Javier González-Rocha, Brian R. Greene, Marcelo I. Guzman, Adam L. Houston, Ashraful Islam, Osku Kemppinen, Dale Lawrence, Elizabeth A. Pillar-Little, Shane D. Ross, Michael P. Sama, David G. Schmale Iii, Travis J. Schuyler, Ajay Shankar, Suzanne W. Smith, Sean Waugh, Cory Dixon, Steve Borenstein, Gijs De Boer

Chemistry Faculty Publications

Small unmanned aircraft systems (sUAS) are rapidly transforming atmospheric research. With the advancement of the development and application of these systems, improving knowledge of best practices for accurate measurement is critical for achieving scientific goals. We present results from an intercomparison of atmospheric measurement data from the Lower Atmospheric Process Studies at Elevation—a Remotely piloted Aircraft Team Experiment (LAPSE-RATE) field campaign. We evaluate a total of 38 individual sUAS with 23 unique sensor and platform configurations using a meteorological tower for reference measurements. We assess precision, bias, and time response of sUAS measurements of temperature, humidity, pressure, wind speed, and …

Nanomedicine-Based Immunochemotherapy For The Mr Imaging And Treatment Of Triple Negative Breast Cancer, Saloni Darji

Electronic Theses & Dissertations

Cancer is known to be a detrimental disease and it accounts for many deaths every year. In women Triple negative breast cancer (TNBC) known to be a very aggressive type of tumor. Current treatment approaches are abortive and have many side effects. With the recent advances in nanotechnology and immunotherapy for cancer treatment, we have designed new nanomedicine that combines both the aspects of cancer treatment. In this work, we have developed an anti-PD-L1-conjugated, Doxo-SS-Gd MR imaging agent encapsulating iron oxide nanoparticles (IONPs) to form IONP-Doxo-SS-Gd-PD-L1 nanomedicine for the targeted MR imaging and treatment of TNBC. The anti-PD-L1 acts as …

High Performance Carbon Derived From Soybean Waste For Energy Storage Applications, Chen Zhao

Electronic Theses & Dissertations

The ever-increasing energy demands of daily life by devices such as portable electronics, vehicle equipment, and medical instruments stimulate development of highly efficient, cost-effective, and non-polluting materials for energy storage applications. Bio-based carbon material is the most promising and greenest class of electrodes based on the principle of the electrical double layer capacity, which has many merits such as high efficiency, long lifespan, fast charge-discharge rate, etc. for energy storage devices. In this study, combining carbonization and chemical activation processes through KOH, micropore and mesopore structures of soybean shells, stems, and leaves are successfully synthesized. Physical morphology and structures of …

Thermotropic Liquid-Crystalline And Light-Emitting Properties Of Poly(Pyridinium) Salts Containing Various Diamine Connectors And Hydrophilic Macrocounterions, Tae Soo Jo, Haesook Han, Pradip K. Bhowmik, Benoît Heinrich, Bertrand Donnio

Chemistry and Biochemistry Faculty Research

A set of poly(pyridinium) salts containing various diamine moieties, as molecular connectors, and poly(ethyleneglycol)-4-nonylphenyl-3-sulfopropyl ether, thereafter referred to as “Macroion”, as the hydrophilic counterion, were prepared by metathesis reaction from the respective precursory tosylated poly(pyridinium)s in methanol. The structure of these ionic polymers was established by spectroscopy and chromatography techniques. The shape-persistent ionic poly(pyridinium) materials, inserting rigid or semi-rigid diamine spacers, display thermotropic liquid-crystalline properties from room-temperature up to their isotropization (in the temperature range around 160–200 °C). The nature of the LC phases is lamellar in both cases as identified by the combination of various complementary experimental techniques including …

Blocking Recombinations In Dscs Through Mgo And Pfts Surface Treatments, Kayla Foell

Honors Theses

High voltage dye-sensitized solar cells (DSCs) are becoming novel sources in the production of various fuel precursors, such as carbon monoxide and hydrogen, by powering carbon dioxide reduction, water oxidation, and proton reduction catalysts via sunlight. An important task in order to increase overall efficiency of DSC devices is to minimize recombination (electron flow in an undesirable direction) while increasing photovoltage. Surface treatment modifications can be applied to the TiO2 electrodes within DSC devices in an effort to block recombination without negatively effecting the other device performance metrics: fill factor (FF), short-circuit current density (Jsc), and open-circuit photovoltage (Voc). In …

Theoretical And Experimental Vibrational Modes Of The Borane Pyridine Complex, Benjamin Stratton

Honors Theses

Benjamin Wade Stratton: Theoretical and Experimental Vibrational Modes of the Borane Pyridine Complex (Under the direction of Dr. Nathan Hammer) The Borane Pyridine complex is a molecule that contains a dative bond between the boron and nitrogen atoms. A dative bond is a type of covalent bonding that occurs when both electrons come from the same atom. The B-N bond has been studied in several other molecules such as ammonia borane and determining the frequency at which this bond vibrates has been a topic of interest studied in these molecules as well as several others. This complex has another factor …

On The Ability Of Pnicogen Atoms To Engage In Both Σ And Π-Hole Complexes. Heterodimers Of Zf2C6H5 (Z = P, As, Sb, Bi) And Nh3, Wiktor Zierkiewicz, Mariusz Michalczyk, Rafał Wysokiński, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

When bound to a pair of F atoms and a phenyl ring, a pyramidal pnicogen (Z) atom can form a pnicogen bond wherein an NH₃ base lies opposite one F atom. In addition to this σ-hole complex, the ZF₂C₆H₅ molecule can distort in such a way that the NH₃ approaches on the opposite side to the lone pair on Z, where there is a so-called π-hole. The interaction energies of these π-hole dimers are roughly 30 kcal/mol, much larger than the equivalent quantities for the σ-hole complexes, which are only 4–13 kcal/mol. On …

Implementation Of Computational Chemistry As Part Of The Physical Chemistry Curriculum, Erica Hess

Honors Program Theses and Projects

Physical chemistry is a sub-discipline of chemistry that focuses on the study of matter at the molecular and atomic level. Since physical chemistry provides foundational knowledge necessary to explain concepts ranging from atomic to molecular structure, chemical reactions and dynamics, to spectroscopy properties of chemical and biochemical systems, it has deeper connections to all other sub-fields of chemistry. Therefore, it is imperative for undergraduate students within chemical science baccalaureate degree programs have a comprehensive understanding of physical chemistry concepts. However, many students taking physical chemistry at an undergraduate level often cannot see its inherent connections to other chemistry sub-disciplines. This …

Structures, Energetics, And Vibrational Frequencies Of Microhydrated Hexafluorophosphate, Pf6−(H2o)N=1,2 From Dft And Ab Initio Computations, Yasmeen Abdo

Honors Theses

This study systematically examines an anion commonly used in room temperature ionic liquids, hexafluorophosphate PF6−, and its non-covalent interactions with up to two explicit water molecules (PF6 − (H2 O)n where n = 1, 2). Initial low-energy configurations are identified via a set of relaxed angular scans across the edges and faces of the PF6− octahedron using the global hybrid M06-2X density functional with a triple-ζ correlation consistent basis set augmented with diffuse functions on all non- hydrogen atoms (cc-pVTZ for H and aug-cc-pVTZ for P, O, F; denoted haTZ). Full geometry optimizations are performed on these initial structures using …

A More Efficient Method For Extracting And Analyzing Pesticides In Baby Foods, Oluwatobi Fabunmi

Master of Science in Chemical Sciences Theses

Pesticides that are used to control pests such as insects, rodents, bacteria, mold, and fungus in food production end up in the fruits and vegetables that we consume. Clearly, concentration levels of pesticides must be carefully monitored. Successful monitoring of the concentrations is critically dependent upon pesticide extraction efficiency, the pesticide structure and the matrix (food product) in which the pesticide is found. Variables such as polarity, solubility, and pH must be investigated. A common approach to develop analysis methods involves spiking food products with pesticides and evaluating method efficiency by calculating percent recoveries from the foods. Sample results from …

Structures Of Clusters Surrounding Ions Stabilized By Hydrogen, Halogen, Chalcogen, And Pnicogen Bonds, Steve Scheiner, Mariusz Michalczyk, Wiktor Zierkiewicz

Chemistry and Biochemistry Faculty Publications

Four H-binding HCl and HF molecules position themselves at the vertices of a tetrahedron when surrounding a central Cl-. Halogen bonding BrF and ClF form a slightly distorted tetrahedron, a tendency that is amplified for ClCN which forms a trigonal pyramid. Chalcogen bonding SF2, SeF2, SeFMe, and SeCSe occupy one hemisphere of the central ion, leaving the other hemisphere empty. This pattern is repeated for pnicogen bonding PF3, SeF3 and AsCF. The clustering of solvent molecules on one side of the Cl- is attributed to weak attractive interactions between them, including chalcogen, pnicogen, halogen, and hydrogen bonds. Binding energies of …

A Robust And Automated Deconvolution Algorithm Of Peaks In Spectroscopic Data, William Johan Burke Iv

Theses and Dissertations

The huge amount of spectroscopic data in use in metabolomic experiments requires an algorithm that can process the data in an autonomous fashion while providing quality of analysis comparable to manual methods. Scientists need an algorithm that effectively deconvolutes spectroscopic peaks automatically and is resilient to the presence of noise in the data. The algorithm must also provide a simple measure of quality of the deconvolution. The deconvolution algorithm presented in this thesis consists of preprocessing steps, noise removal, peak detection, and function fitting. Both a Fourier Transform and Continuous Wavelet Transform (CWT) method of noise removal were investigated. The …

Decrypting Female Attractivity In Garter Snakes, Holly Rucker

Senior Honors Projects, 2010-2019

Pheromones are utilized by many species as sexual signals driving mate choice, and pheromone production in vertebrates hinges on sex hormone action. Female red-sided garter snakes (Thamnophis sirtalis parietalis) produce a skin-based sex pheromone used by males for mate detection and selection. Estradiol is necessary for pheromone production, yet the specific mechanisms within the skin are unknown. Central to this is the metabolism of testosterone to estradiol via the enzyme aromatase. It is hypothesized that female garter snakes synthesize estradiol locally in the skin and maintain pheromone production via tissue-specific regulation of aromatase. Further, I hypothesize that female …

Obscurin Is A Semi-Flexible Molecule In Solution, Jacob Whitley

Senior Honors Projects, 2010-2019

Obscurin, a giant modular cytoskeletal protein, is comprised mostly of tandem immunoglobulin-like (Ig-like) domains. This architecture allows obscurin to connect distal targets within the cell. The linkers connecting the Ig domains are usually short (3-4 residues). The physical effect arising from these short linkers is not known; such linkers may lead to a stiff elongated molecule or, conversely, may lead to a more compact and dynamic structure. In an effort to better understand how linkers affect obscurin flexibility, and to better understand the physical underpinnings of this flexibility, here we study the structure and dynamics of four representative sets of …

Investigations Of The Mechanism Of Action For Lung Cancer Cell Death By A 4-Trifluoromethoxy Substituted Chalcone, Trevor M. Stantliff

Undergraduate Theses

Chalcones are a diphenyl compound that serves as a natural precursor to flavonoids in plants. Chalcones have been shown to have anticancer and antimicrobial activities. Chemoprevention activity of chalcones are of high interest in medicinal chemistry because of the simple laboratory synthesis and modification via Claisen-Schmidt condensation. Previously this lab created and screened a library of synthetic chalcones against A549 lung adenocarcinoma cell line for antiproliferation properties. We identified a strong drug candidate (4-trifluoromethoxy substituted chalcone) for A549 growth inhibition. However, the cause of inhibition by the substituted chalcone remains to be identified We began to explore the mechanism of …

Synthesis Of Piperidine-Based Inhibitors Of Kasa, A Vital Enzyme Of M. Tuberculosis, Lindsey Jones

Departmental Honors & Graduate Capstone Projects

Tuberculosis is the leading cause of death from infectious disease in the world. Although tuberculosis drugs exist, the rise of drug-resistant tuberculosis has created a need for new research. Identifying novel, effective drugs for treatment of tuberculosis could reduce the cost of care and treatment time, saving millions of lives. The enzyme KasA, which synthesizes part of the tuberculosis bacterial cell wall, has been identified as an attractive drug target. A virtual screen using KasA discovered a compound, 4-(4-bromophenyl)-1-pyrenemethyl-4-piperidinol (1), which inhibited bacterial growth in vitro. In this research, nine derivatives of compound 1 were synthesized for future testing …

Caspases And Cancer: Connections Through Circular Dichroism Spectroscopy, Sarah M. Hethcox

Honors College Theses

While excessive cell death inevitably leads to negative effects, the endurance of damaged cells in the presence of death signals can be equally detrimental to health. Apoptosis, or programmed cell death, is a highly regulated process in which cues from within or from outside a cell can trigger an irreversible sequence of signals that carry out cell destruction known as the apoptotic cascade. A group of enzymes called caspases play a vital role in this cascade with some participating as initiators and others acting as effectors of protein cleavage and intracellular breakdown. Although it is normal for the activity of …

Elemental Analysis Of Edible Clay From The Copperbelt Province Of Zambia, Amelia M. Craze, Mina L. Brandon

Venture: The University of Mississippi Undergraduate Research Journal

Trace elements in three edible clay samples from an open-air market in Kitwe, Zambia were analyzed for heavy metals using a scanning electron microscope coupled with an energy-dispersive spectrometer. The ingestion of clays has been observed throughout history but persists in many rural countries that lack sufficient access to proper medical care. In many African countries, women have been observed eating clay during pregnancy to reduce nausea or meet their recommended intake of iron. Similar studies identified harmful heavy metals in the makeup of the edible clays, however, the results of this analysis elemental analysis coupled with the SEM for …

Modifying Inhibited Primer Performance Via Control Of Epoxy-Amine Matrix Structure And Composition, Steven Wand

Dissertations

This research represents an effort to deliver a new fundamental understanding of how polymer matrix characteristics influence corrosion protection of organic coatings, in particular the performance of corrosion inhibitor-containing primers. By modifying the structure and composition features of epoxy-amine matrices which commonly serves as the binder for protective coatings, the thermal/mechanical, adhesion, and transport properties which govern coating performance and inhibitor release were altered in such a way that directly influenced protection efficacy. This research is composed of three distinct approaches towards systematically varying thermoset network characteristics and observing the resulting impact on transport behaviors and corrosion prevention, with an …

“Polysoaps” Via Raft Copolymerization To Form Well-Defined Micelles For Water Remediation And Targeted Drug Delivery Applications, Phillip Pickett

Dissertations

Amphiphilic copolymers have become increasingly important for environmental and biological applications due to their behavioral characteristics in aqueous solution. For example, structurally-tailored statistical amphiphilic copolymers or “polysoaps” can self-assemble into micelles or other architectures in water at various concentrations. Polysoaps may be differentiated from small molecule surfactant micelles in their capability to self-assemble into unimolecular associates (unimolecular micelles) with no dependence on concentration. Such micelles offer enormous potential for dispersion of hydrophobic species in water at high dilution. Importantly, each polymer chain forms its own micelle and upon dilution, these micelles remain intact and capable of dispersing hydrocarbon material in …

Engineering Multifunctional And Morphologically Diverse Polymer Brush Surfaces, Cassandra M. Reese

Dissertations

The combination of surface-initiated polymerization (SIP) and post-polymerization (PPM) serves as a powerful approach to fabricate complex, multifunctional polymer films, which can be precisely tuned for desired surface engineering applications. Careful manipulation of PPM parameters such as reaction conditions, the tethered brush parameters, and the physical properties of the unbound post-modifier greatly influence the depth of penetration of the post-modifier and the polymer brush compositional heterogeneity. This dissertation focuses on engineering polymer brush surfaces with multifunctional chemistries and tunable morphologies by investigating the PPM parameters that dictate the distribution of post-modifiers on grafted polymer brush surfaces.

The first chapter of …

Manipulation Of Noncovalent Interactions For The Synthesis And Use Of Natural Product Synthons, Alison P. Hart

Dissertations

Natural products are widely used in the pharmaceutical industry, in agriculture, and as specialty chemicals. Methodology development focuses on optimizing the key organic reactions to access these natural products while trying to limit the overall number of synthetic steps. Key bond forming strategies are sought to provide new ways to address carbon-carbon or carbon-heteroatom bonds. The advancement of new asymmetric reactions to generate enantiopure products from achiral starting materials is a vital area of research. The objectives addressed in this dissertation include: 1) the development of a general reductive conversion of esters to ethers with a broad substrate scope accessing …

Evaluating Corrosion Altering Properties Of Thiophene Based Copolymers, Robert Peterson

Dissertations

There is an important and ongoing debate on how or whether conductive polymers (CP) alter corrosion performance with some researchers reporting that CPs ultimately accelerate corrosion and others saying CPs, if understood could possibly replace the world’s best standard for corrosion prevention, i.e., chromium based inhibitors. The primary project goal was to improve our understanding of how CPs alter corrosion chemistry by 1) controlling the polymer structure and 2) in-turn the properties and then 3) targeting the best protocol for fast corrosion kinetic evaluation.

We detail the copolymer synthesis results and shift in corrosion protection properties for …

Nanopore Sensing For Single-Molecule Glycomics, Melissa Morris

Senior Honors Projects

Single-molecule sensing represents the ultimate in chemical sensitivity, but is tremendously challenging to achieve. Larger proteins have a diameter of 10 nm, which is 1/10,000^th the size of a strand of hair, and 1/100,000^th the size of a grain of sand. Because imaging at the nanoscale is difficult and expensive, developing techniques to measure single molecules requires ingenuity, and often relies on the interpretation of electrical signals. So how do nanopores help us measure at the single-molecule level?

A nanopore is simply a nano-sized hole in a membrane or material. In the early stages of nanopore science, biological …

Engineering Noble-Metal Nanostructures For Biosensing Applications, Haihang Ye

Electronic Theses and Dissertations

The ability to engineer noble-metal nanostructures (NMNSs) in a controllable manner and to understand the structure-dependent properties greatly boost our knowledge in rational design of biosensing technologies. In particular, as a type of highly efficient peroxidase mimics, NMNSs hold promising potential to break through the bottleneck of conventional enzyme-based in vitro diagnostics. During the time of my Ph.D. study, I have successfully: 1) directed a two-step method involving seed-mediated growth and chemical etching for the synthesis of Ru nanoframes (RuNFs) with face-centered cubic crystal phase and enhanced catalytic activities; 2) demonstrated, for the first time, the inherent peroxidase-like activity of …

Strictinin, A Novel Ror1-Inhibitor, Represses Triple Negative Breast Cancer Survival And Migration Via Modulation Of Pi3k/Akt/Gsk3ss Activity., Norman Fultang, Abhinav Illendula, Brian Chen, Chun Wu, Subash C. Jonnalagadda, Nathan Baird, Zachary Klase, Bela Peethambaran

College of Science & Mathematics Departmental Research

Triple Negative Breast Cancer (TNBC), the most aggressive subtype of breast cancer, is characterized by the absence of hormone receptors usually targeted by hormone therapies like Tamoxifen. Because therapy success and survival rates for TNBC lag far behind other breast cancer subtypes, there is significant interest in developing novel anti-TNBC agents that can target TNBC specifically, with minimal effects on non-malignant tissue. To this aim, our study describes the anti-TNBC effect of strictinin, an ellagitanin previously isolated from Myrothamnus flabellifolius. Using various in silico and molecular techniques, we characterized the mechanism of action of strictinin in TNBC. Our results suggest …