Physical Sciences and Mathematics Commons^™

Synthesis And Characterization Of Nanocomposite Sensing Films For Breath Sensors, Tara Mercer

Undergraduate Honors Theses

Lung cancer is one of the most common and fatal cancers today, infecting 1 in 16 people, and killing well over a million patients per year. Currently, lung cancer is detected usually in stages three and four by quite costly and invasive methods, which shows only a survival rate of 10%. Breath sensors provide a low-cost and non-invasive technique for early screening of lung cancer. The breath sensors use assemblies of gold nanoparticles to identify lung cancer, specifically by identifying and quantifying specific volatile organic compound (VOC) concentrations found in the breath of lung cancer patients. This thesis describes a …

Relative Reactivity Of Six Amino Acids With Sodium Hypochlorite Measured By Gas Chromatography/ Mass Spectrometry And Methyl Chloroformate Derivatization., Josephine Wangui Gitau

Electronic Theses, Projects, and Dissertations

There are 20 common amino acids that act as building blocks for proteins and each one of them differ from each other due to their chemical structure of the R group. During the process of chlorination of water and wastewaters, amino acids present have been implicated as precursors of disinfection by-products. For the analysis of amino acids Gas Chromatography/Mass Spectrometry (GC/MS) is widely used. In this research six amino acids (glycine, valine, leucine, isoleucine, methionine, and phenylalanine) were derivatized with Methyl Chloroformate and analyzed using Gas Chromatography/Mass Spectrometry without heating. The main aim of this study was to observe the …

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

Electronic Theses and Dissertations

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

The Effects Of Prior Calculus Classes On Success In Organic Chemistry, Tori Williamson

Theses/Capstones/Creative Projects

Within University of Nebraska – Omaha (UNO) chemistry-based degree programs, organic chemistry along with at least two semesters of calculus are required courses. There is, however, no requirement for the order in which these courses should be taken. This is mainly due to the notion that for chemistry courses, organic chemistry is detached from the typical quantitative concepts studied in other chemistry-based courses. This is untrue, however, as many organic chemistry concepts rely on three-dimensional spatial visualizations and manipulations. Spatial awareness skills are strengthened within higher-level calculus classes. A survey was administered to organic chemistry students enrolled in 2022-2023. The …

The Impact Of Glacial Proximity On The Elemental Composition Of Leachate Derived From Sediment Weathering, Karoline Ford

Theses/Capstones/Creative Projects

This study assesses chemical weathering trends as they relate to glacial retreat. The chemical environment of surfaces exposed to the atmosphere differs significantly from beneath a glacier. As a glacier melts, changes to the biogeochemical processes generate environmental gradients. This study analyzed chemical weathering signals at different distances from a glacial front by comparing the elemental composition of leachate derived from sediments in southeastern Greenland. Samples from proglacial, nonglacial, and moraine locations were weathered in a laboratory setting, and ion chromatography was used to determine the elemental composition of the products. Divergent trends in leachate composition were observed as distance …

Spin Trapping Behavior Of Some Selected Melatonin Derivatives For Hydroxyl Radicals: A Computational Study, Aaron Caesar

Electronic Theses and Dissertations

Melatonin (N-acetyl-5-methoxytryptamin, MLT) is a naturally occurring antioxidant which has shown some potential for use as a spin trap. Spin traps react with short lived hydroxyl radicals (HO·) to produce more stable products called spin adducts which may be characterized by electron paramagnetic resonance spectroscopy. However, the relative stability of hydroxyl spin adducts of melatonin derivatives (MLTD) compared to 2-hydroxymelatonin (HO-MLT) has not been examined computationally. Computational studies have been done on four selected MLTD; methylmelatonin (Me-MLT), chloromelatonin (Cl-MLT), cyanomelatonin (CN-MLT), and nitromelatonin (NO₂-MLT). Geometry of the structures were optimized at the HF/6-31G(d), cc-pVXZ, (X=D and T) and …

Molecular Evidence For The Export Of Terrigenous Organic Matter To The North Gulf Of Mexico By Solid-State 13C Nmr And Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Of Humic Acids, Sarah Ann Ware

Chemistry & Biochemistry Theses & Dissertations

Marine organic matter is mainly believed to originate from autochthonous organic matter, while terrigenous organic matter is assumed to be largely degraded prior to reaching the open ocean or more recently replaced by marine organic matter via a stripping process. Sediment samples along a transect extending from the Mississippi River Birdsfoot Delta to the Mississippi Canyon on the Louisiana continental shelf were examined by advanced analytical techniques, electrospray ionization coupled to a 12T Fourier transform ion cyclotron resonance mass spectrometer (ESI-FTICR-MS) and quantitative solid-state multiple cross polarization magic angle spinning (multi-CPMAS) ¹³C NMR in an effort to understand the …

The Development Of Tailored Amphiphilic Copolymers For Detergent-Free Integral Membrane Protein Extraction, Cameron Edward Workman

Doctoral Dissertations

Integral membrane proteins are prolific targets for the design, development, and delivery of pharmaceuticals. In fact, over 60% of all currently available drugs target these proteins to accomplish their therapeutic effect. However, integral membrane proteins remain the least characterized class of all proteins, accounting for only ~2% of all solved protein structures. One of the primary reasons for this low number of solved protein structures is that many membrane proteins lose their native conformation when extracted using conventional methods (e.g. detergents), convoluting accurate structure determination. In contrast, amphiphilic styrene-maleic acid copolymers (SMAs) were recently discovered to readily isolate membrane proteins …

Development Of Surface-Modified Liposomes For Drug Delivery Applications, Megan Louise Qualls

Doctoral Dissertations

Liposomes are spherical vesicles composed of a lipid bilayer membrane that assembles around an internal aqueous core. This duality gives liposomes the ability to encapsulate both hydrophobic cargo within the lipid bilayer and hydrophilic cargo in the aqueous core, making them versatile molecular carriers for drug delivery. Liposome platforms have many advantages and are promising drug delivery carriers, and research is ongoing to improve their designs for continued clinical applications. Many liposome types have been developed, but further work is needed to improve surface modification, site-specific targeting, and triggered cargo release in order to further the therapeutic applications of these …

Determination Of Cadmium Uptake In Crassostrea Virginica Shell Under Controlled Conditions, Joseph John Pavelites Ii

<strong> Theses and Dissertations </strong>

The objective of this thesis was to meet growing demand for the development of environmental biomonitors that protect ecosystems and public health. To do this, I determined the potential of oyster shell as a bioindicator of cadmium (Cd) in the environment by determining the mode of Cd uptake and relationships between Cd concentrations in the environment, shell, and soft tissues of juvenile eastern oysters (Crassostrea virginica Gmelin). I performed a review of the literature on the ability of oyster shell to retain metal contaminants and the factors that could affect this process (Chapter 2). I then reared C. virginica …

Characterizing Metabolic Activity Of Fish Liver Microsomes Towards Fluoxetine In Four Fish Species Using Michaelis-Menten Enzyme Kinetics, Morgan Steiner

Honors College Theses

Discharge of pharmaceuticals into the environment is of emergent concern due to the unknown long-term effects on aquatic organisms. Wastewater treatment plants are not effective in completely removing pharmaceuticals, allowing them to be discharged into aquatic systems. To investigate the potential effects of fluoxetine, a common antidepressant, on aquatic species, the potential of four freshwater fish species to metabolize this drug was investigated. Livers from redbreast sunfish, bluegill, striped jumprock and bluehead chub were collected, homogenized, and centrifuged to collect the microsomes. These microsomes were used in an assay to determine the in vitro hepatic metabolism of fluoxetine by cytochrome …

Nitroalkane Oxidase Inspired No-Transfer Agents, No Sensors, And The Computational Design Of Fluorescent Sensors, Thanh Thuy Thi Vuong

Chemistry & Biochemistry Dissertations

Flavin adenine dinucleotide and flavin mononucleotide are co-enzymes with biologically relevant redox potentials. They are involved in many chemical transformation processes in the biological system, such as one-electron and two-electron transfer reactions, dehydrogenase reactions, and intramolecular electron transfer reactions critical to cellular function. Their ability to be reoxidized under aerobic conditions has inspired us to investigate biomimetic transformations with their derivatives, especially in converting NO2 to NO. Besides that, a series of biosensors was designed and investigated to detect NO in the aqueous system. NO sensors were achieved with computational DFT calculations correctly predicting the fluorescence response.

Epimeric Peptides In Alzheimer’S Disease: Implications For Liquid Chromatography-Mass Spectrometry And Immunotherapies, Elizabeth Readel

Chemistry & Biochemistry Dissertations

Evidence has shown that the extracellular deposition of amyloid-beta (Aβ) peptide is a contributing factor of Alzheimer’s disease. Further, modifications to Aβ peptides may enhance the deposition of Aβ plaques and/or contribute to the neurodegeneration in AD patients. These aberrations include the isomerization and epimerization of L-Asp and D-Ser residues to form D-Asp, L/D-iso-Asp, and D-Ser residues, respectively. Therefore, considerable effort has been expended to create effective methods to distinguish such aberrant Aβ peptides from wild type. A useful technique to extract aberrant Aβ peptides in AD patients is by immunotherapies, or antibodies. A few immunotherapies are thought to provide …

An Investigation Of Peak Shape Models In Chiral Separations, Ryan Jacob Burk

Chemistry & Biochemistry Theses

The use of superficially porous particles in chromatography has led to significant improvements in separation efficiency. However, peak asymmetry in enantiomeric separations causes performance comparisons across particle types a challenge. In this study, we screened 28 pharmaceutically relevant compounds and developed practical methods to reduce peak asymmetry in normal phase chiral chromatography. The use of additives was found to be effective in reducing peak tailing for all compounds, including neutrals. Additionally, we observed that solvent mismatch with the eluent can cause system peak interference, which can be managed by reducing injection volumes. To more accurately assess the performance of the …

Stoichiometric Determination Of Hydride Materials At Extreme Conditions, Gregory Alexander Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen was predicted to be a high-temperature superconductor at near-megabar conditions in 1968,[1] but only recently was been experimentally observed.[2] This is due to the extraneous metrological constraint of requiring 5 megabars of pressure to stabilize. A more practical approach for synthesis of high-temperature superconductors has been pro-posed through the use of hydride compounds. Recently, a surge of rare earth hydrides have achieved critical superconducting transition temperatures (T_C ) close to room temperature.[3, 4, 5, 6] However, due to limitations of the necessary instrumentation to achieve megabar pressures, many techniques traditionally used to measure stoichiometry are unavailable.Three works presented in …

Synthesis, Radiolabeling And Evaluation Of A Suite Of Tracers With 44Sc For Detecting Extracellular Dna, Zhiyao Li

McKelvey School of Engineering Theses & Dissertations

Neutrophil extracellular traps involve the rapid translocation of DNA to the outside of the cell under certain stimuli. This structure forms a fibrous network that is able to limit the spread of pathogens and to kill microorganisms. It has also been shown to be present in various pathological processes such as inflammation, autoimmune diseases, and cancer metastasis. Currently, the formation process of NETs in vivo is being extensively studied. However noninvasive detection and quantitation has yet to be achieved. A class of PET tracers are described here that consists of a DNA dye as the backbone that is labeled with …

Excitation Power Dependence Of Blinking In Copper-Indium-Sulfide Quantum Dots, Nicholas Chambers

Physics Undergraduate Honors Theses

Under continuous excitation, quantum dots exhibit random transitions between fluorescent ON states and non-fluorescent OFF states --- a phenomenon known as blinking. A physical description of the mechanism responsible for blinking that applies broadly to many types of quantum dots remains under debate. We study the blinking behavior of the non-toxic CuInS2 quantum dot, a system that has seen little investigation at the single-particle level. In particular, the optical properties of CuInS2 quantum are often improved by adding ZnS to the nanoparticles, but this addition leads to complex structural-optical property relationships that are even less understood. To probe the relationship …

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

Electronic Theses and Dissertations

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

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

Electronic Theses and Dissertations

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

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

Impacts Of Preferential Flow On Tc-99and Np-237 Vadose Transport In Soils At The Savannah River Site, Josh Parris

All Theses

Since the 1950s, the United States has produced approximately 90,000 metric tons of spent nuclear fuel (SNF) (Office of Nuclear Energy, 2022); however, no long-term storage solutions are available. Technecium-99 and neptunium-237, two fission products found in SNF, readily form highly mobile species in oxidizing conditions (Hu, 2008; Bondietti, 1979) and have respective half-lives of 2.13 x 10⁵ and 2.14 x10⁶ years (Hu, 2010). Considering these characteristics, ⁹⁹Tc and ²³⁷Np are two risk-driving isotopes found in SNF storage. The process of macropore-facilitated preferential flow, transport through cracks within a soil matrix, has been recognized to increase …

Anxiety-Like Behavior In C57bl/6j Mice Is Sexually Dimorphic And Altered By Buprenorphine, Ohm Sharma

Chancellor’s Honors Program Projects

No abstract provided.

Supramolecular Pi-Donor/Acceptor Arrays Based On Redox-Active Metal-Organic Coordination Assemblies, Paola Benavides

All Dissertations

Coordination-driven self-assembly is an attractive strategy for constructing thermodynamically stable supramolecular coordination complexes, ranging from discrete metallacycles and cages to infinite coordination polymers and metal-organic frameworks for a variety of applications.

Chapter 1 discusses strategies for preparing supramolecular charge-transfer π-donor/acceptor assemblies and their potential applications.

Chapter 2 demonstrates that tricomponent self-assembly method, which was believed to yield 3D-cages, based on tetrapyridyl porphyrin (M’TPP, M’ = Zn or H₂), dicarboxylate ligands (XDC), and caped cis-Pt(II) corners, actually yields 2D-bowties featuring an M’TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. The 2D-bowties showed …

Separating The R Vs. S Enantiomers Of A Quinoline Aimed At Inhibiting The Allosteric Binding Pocket Of Hiv-1 Integrase, Madison Canfield

Honors Theses

HIV-1 is a retroviral disease that infects CD4+ T cells in the body. Once inside the body, HIV-1 uses human cell machinery to replicate and reproduce using several enzymes to reverse transcribe viral RNA to DNA and integrate the viral DNA into the human genome to reproduce. Several drugs, such as NRTIs, INSTIs, NNRTIs, and PIs, have been created to inhibit specific parts of the viral life cycle and are used in combination to fight HIV-1. However, these medications face challenges of viral mutation and resistance, which increases the importance of creating more potent and effective drugs. Recently, a new …

Quantum Chemistry–Machine Learning Approach For Predicting Properties Of Lewis Acid–Lewis Base Adducts, Hieu Huynh, Thomas J. Kelly, Linh Vu, Tung Hoang, Phuc An Nguyen, Tu C. Le, Emily Jarvis, Hung Phan

Chemistry and Biochemistry Faculty Works

Synthetic design allowing predictive control of charge transfer and other optoelectronic properties of Lewis acid adducts remains elusive. This challenge must be addressed through complementary methods combining experimental with computational insights from first principles. Ab initio calculations for optoelectronic properties can be computationally expensive and less straightforward than those sufficient for simple ground-state properties, especially for adducts of large conjugated molecules and Lewis acids. In this contribution, we show that machine learning (ML) can accurately predict density functional theory (DFT)-calculated charge transfer and even properties associated with excited states of adducts from readily obtained molecular descriptors. Seven ML models, built …

Developing Chemo-Proteomics Methods For Tyrosine Conjugation And Studies Of Organometallic Complexes Of Gold., Adway Ouseph Zacharias

Chemistry & Biochemistry Dissertations

The incredible changes in MS instrumentation since the late 1980s with the advent of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) has revolutionized protein chemistry. Mass spectrometry coupled with chemical crosslinking is a powerful tool to decipher protein structure and protein-protein interactions. A majority of commercially available crosslinkers target only few amino acid residues such as lysine, arginine and cysteine, thereby limiting the utility of this technology. The prospect of using chemical reagents to target amino acids is challenging since covalent labeling experiments are performed under physiological aqueous conditions that may be detrimental to the stability of these reagents. …

Analysis Of Isotopic Isomers By Gas Chromatography And Molecular Rotational Resonance Spectroscopy And Enantioselective Method Development By Liquid Chromatography, Saba Aslani

Chemistry & Biochemistry Dissertations

This dissertation focuses on developing improved methods and a better understanding of gas and liquid chromatographic separation of isotopic isomers and enantiomers. The second and third chapters of this thesis discuss analytical determination of isotopic isomers using gas chromatography. Deuterated compounds have found applications in many fields. They are used in drug discovery due to increased stability and bioavailability and reduced toxicity of the deuterated drug molecules. Also, deuterated compounds are used to investigate reaction mechanisms and rate determining steps. One of the methods of synthesizing deuterated compounds is starting from lower molecular weight deuterated building blocks. Therefore, analysis and …

Combining Chiral Chromatographic Stationary Phases And N-Derivatization Strategies For The Qualitative And Quantitative Analysis Of D-Amino Acids, D-Amino Acid Containing Peptides And D-Amino Acid Related Secondary Metabolites Using Liquid Chromatography, Sam Sung

Chemistry & Biochemistry Dissertations

Amino acids are essential building blocks in all life on Earth. It was first mistakenly believed that only L-amino acids were of biological relevance in higher organisms, and D-amino acids were laboratory artifacts or biologically irrelevant. It is well accepted today that various D-amino acids exist in different organisms, including humans, and some even play critical roles in biological pathways and processes. In addition, aberrant levels of certain D-amino acids have been reported in patients with varying diseases. It has been proposed that the aberrant variations in the levels of D-amino acids in biological fluids may serve as biomarkers for …

The Search For The Four-Electron Reduced Intermediate In The Cytochrome C Nitrite Reductase (Ccnir) - Catalyzed Reduction Of Nitrite, Victoria Lynn Mandella

Theses and Dissertations

Although there are many nitrogen species in the nitrogen cycle, nitrite occupies a centralrole. Nitrite can either reduce to ammonium or dinitrogen or oxidize to nitrate. Ammonium and nitrate can be found in the environment; however, problems arise when the accumulation of these nitrogen species leads to eutrophication in aquatic environments. High ammonium or nitrate levels in lakes or other bodies of water can lead to the overgrowth of algae, which causes the blockage of sunlight to different species below the water surface. Imbalance in the ecosystem is a serious environmental issue that can be addressed by further studying and …

Modeling Accuracy Matters: Aligning Molecular Dynamics With 2d Nmr Derived Noe Restraints, Milan Patel

Honors Scholar Theses

Among structural biology techniques, Nuclear Magnetic Resonance (NMR) provides a holistic view of structure that is close to protein structure in situ. Namely, NMR imaging allows for the solution state of the protein to be observed, derived from Nuclear Overhauser Effect restraints (NOEs). NOEs are a distance range in which hydrogen pairs are observed to stay within range of, and therefore experimental data which computational models can be compared against. To that end, we investigated the effects of adding the NOE restraints as distance restraints in Molecular Dynamics (MD) simulations on the 24 residue HP24stab derived villin headpiece subdomain to …

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 …