Physical Sciences and Mathematics Commons^™

Three-Dimensional Nanomaterials For Supercapacitor Applications: From Metal Oxides To Metal Phosphides, Zhi Zheng

University of New Orleans Theses and Dissertations

Over the past few years, energy storage devices have received tremendous interest due to the increasing demand for sustainable and renewable energy in modern society. Supercapacitors are considered as one of the most promising energy storage devices because of their high power density and long cycle life. However, low energy density remains as the main shortcoming for supercapacitors. The overall performance of supercapacitors is predominantly determined by the characteristics of the electrodes. Specifically, constructing nanostructured electrode material has been proven as an efficient way to improve the performance by providing large surface area and short ionic and electronic diffusion paths. …

Fabrication And Characterization Of Intricate Nanostructures, Treva T. Brown

University of New Orleans Theses and Dissertations

Encapsulation of nanoparticles within hexaniobate nanoscrolls presents interesting advances in the formation of nanocomposites exhibiting unique multi-dimensional properties. Building upon previous successes, facile yet versatile wet-chemical and microwave-irradiation synthetic protocols for the fabrication of a series of hexaniobate composites are presented herein. Solvothermal and, more recently, microwave-assisted methods have been developed that allow for the fabrication of peapod-like structures. During solvothermal treatment, exfoliated hexaniobate nanosheets scroll around highly ordered chains of preformed nanoparticles (NPs) to produce nanopeapods (NPPs). This approach offers versatility and high yields, in addition to the potential for advanced functional device fabrication.

For the characterization of these …

Quantum Chemical Studies Of Noncovalent Interactions And Multicenter Bonds Utilizing Local Vibrational Modes, Vytor Oliveira

Chemistry Theses and Dissertations

Noncovalent interactions play an important role for the design of novel drugs, better catalysts, synthesis of complex supramolecular structures, and so on. To develop new materials, a well-founded knowledge of how to control the strength of these interactions is desirable. Despite the many investigations done so far, a quantitative assessment of the intrinsic strength of most types of noncovalent interactions is still missing. Recently and for the first time, the Konkoli-Cremer local modes analysis was successfully used to probe the intrinsic strength of hydrogen and pnicogen bonds. We extended these investigations to more than 300 halogen and chalcogen bonds. A …

Adsorbed Gas Behaviour And Guest-Host Interactions In Ultramicroporous Metal-Organic Frameworks, Bligh Desveaux

Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are a class of porous materials that have attracted much attention due to their large surface areas, high tunability and their high selectivity for gas adsorption applications. In this work, solid-state nuclear magnetic resonance (SSNMR) experiments and single crystal X-ray diffraction (SCXRD) experiments are used to investigate carbon dioxide adsorption within the ultramicroporous MOFs SIFSIX-3-Zn (Chapter 2) and ZnAtzOx. (Chapter 3). Analysis finds that the CO₂ SIFSIX-3-Zn undergoes wobbling motions with a low temperature dependence, and in ZnAtzOx undergoes wobbling and hopping motions with a low temperature dependence. SCXRD is used to precisely determine the CO …

Synthesis, Characterization, And Spectroscopy Of Donor-Acceptor Charge Transfer Complexes, Dominic K. Kersi

Chemistry and Chemical Biology ETDs

A series of square-planar metal (diimine)(dichalcogenolene) chromophoric complexes have been synthesized, characterized and studied spectroscopically. Studies conducted on diimineplatinum(II) dichalcogenolene complexes (LPtL’) using time resolved spectroscopic techniques such as transient absorption and emission, reveal a charge-separated excited state of the type dichalcogenolene → diimine charge-transfer (LL’CT) [(dichalcogenolene^•+)Pt(diimine^•-) with an open shell donor-acceptor biradical character. Long-live excited state lifetimes were observed for these complexes upon visible photoexcitation of the LL’CT or MMLL’CT band. A direct linear relationship is observed to exist between photoluminescence rates, calculated SOC matrix elements, and ¹³C-NMR chemical shifts.

A series of …

Two-Component Hydrogel As Biomimetic Vitreous Substitutes, Sruthi Santhanam

McKelvey School of Engineering Theses & Dissertations

The vitreous humor of the eye is a biological hydrogel principally composed of fibrillary collagen interspersed with semi-flexible polyelectrolyte, hyaluronic acid (HA). Certain pathological conditions necessitate its removal and replacement. Current vitreous substitutes, such as silicone oils and perfluorocarbons, are hydrophobic, do not resemble the properties of the vitreous, and have known complications. An ideal vitreous substitute should have properties of the natural vitreous, perform its functions, and be biocompatible in the eye. Inspired by the structure and composition of the natural vitreous, we used bio-mimicry to develop an injectable two-component hydrogel. The hydrogel is composed of a fibrillary gellan, …

New Ventures In Amidine-Based Catalyst Design, Nicholas Alan Ahlemeyer

Arts & Sciences Electronic Theses and Dissertations

Two new cascade transformations of α,β-unsaturated thioesters catalyzed by amidine-based catalysts have been developed. First, a reagent-free transformation of o-formylaryl cinnamoyl thioesters catalyzed by HBTM-2 to produce 2-substituted thiochromenes achieved high enantioselectivities and yields while forming carbon dioxide as the only byproduct. Second, a highly diastereo- and enantioselective tandem rearrangement of less reactive enone thioesters into tricyclic thiochromanes in the presence of electron-rich amidine-based catalysts was developed. These catalysts were designed with the help of DFT calculations. H-PIP, the first chiral amidine-based catalyst synthesized in our group, performed the best overall in the thiochromane synthesis.

The second chapter of this …

The Chemistry And Biology Of Iron-Scavenging Natural Products From Pathogenic Acinetobacter Baumannii, Justin Shapiro

Arts & Sciences Electronic Theses and Dissertations

Multidrug resistant (MDR) Gram-negative bacteria represent a global health crisis. Traditional antibiotics create selective pressure and breed resistance, making our current drugs less and less effective. Targeting of bacterial virulence factors has gained interest as an alternative strategy to potentially circumvent this problem. Virulent Acinetobacter baumannii synthesize and secrete pre-acinetobactin, a small molecule metal chelator that scavenges life-sustaining iron and is critical for establishing infection. The work described herein sheds light on the unusual properties of a non-enzymatic isomerization from pre-acinetobactin to acinetobactin and proposes a siderophore-swapping mechanism by which A. baumannii expands its pH window for virulence. Knowledge from …

Fabrication And Modification Of Titania Nanotube Arrays For Harvesting Solar Energy And Drug Delivery Applications, Ahmed El Ruby Abdel Rahman Mohamed

Electronic Thesis and Dissertation Repository

The fast diminishing of fossil fuels in the near future, as well as the global warming caused by increasing greenhouse gases have motivated the urgent quest to develop advanced materials as cost-effective photoanodes for solar light harvesting and many other photocatalytic applications. Recently, titania nanotube arrays (TNTAs) fabricated by anodization process has attracted great interest due to their excellent properties such as: high surface area, vertically oriented, highly organized, one-dimensional, nanotubular structure, photoactivity, chemical stability and biocompatibility. This unique combination of excellent properties makes TNTAs an excellent photoanode for solar light harvesting. However, the relatively wide band gap energy of …

The Development Of Peptide Analogues As Potential Fluorescent And Pet Imaging Probes., Neha Sharma

Electronic Thesis and Dissertation Repository

Molecular imaging is a non-invasive way to diagnose disease. Molecular imaging probes consist of a targeting entity that has a high affinity for a biological target and a signaling source for external detection. Multimodality imaging combines the advantages of different imaging modalities, at the same time eliminating their shortcomings, thereby providing more accurate results. This thesis focuses on the development of novel dual PET/fluorescence imaging agents based on peptides as targeting entities.

Porphyrins are suitable for multimodality imaging applications due to their innate characteristics such as an ability to fluoresce and to coordinate metals. A gallium-protoporphyrin IX(PPIX)-ghrelin based analogue was …

Studying Metal-Organic Frameworks Via Solid-State Nmr: Gas Dynamics, Structure Determination, And Phase Transition, Yue Zhang

Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are a class of microporous materials constructed from virtually endless combinations of metal centres and organic linkers. MOFs have attracted intense research interest in recent decades, since MOFs have outstanding properties such as extremely high surface area, tuneable pore topology, good stability, and many others. MOFs are also promising candidates for gas storage. In this work, solid-state NMR (SSNMR) spectroscopy has been investigated to study MOFs and their guest molecules, since SSNMR can provide information on the short-range environment about target nuclei and can also reveal the dynamics of guest molecules.

An introduction to MOFs and SSNMR …

Cellulose Nanofiber-Reinforced Impact Modified Polypropylene: Assessing Material Properties From Fused Layer Modeling And Injection Molding Processing, Jordan Elliott Sanders

Electronic Theses and Dissertations

The purpose of this research was to investigate the use of cellulose nanofibers (CNF) compounded into an impact modified polypropylene (IMPP) matrix. A IMPP was used because it shrinks less than a PP homopolymer during FLM processing. An assessment of material properties from fused layer modeling (FLM), an additive manufacturing (AM) method, and injection molding (IM) was conducted. Results showed that material property measurements in neat PP were statistically similar between IM and FLM for density, strain at yield and flexural stiffness. Additionally, PP plus the coupling agent maleic anhydride (MA) showed statistically similar results in comparison of IM and …

Prep-Hplc Method Development To Isolate Potentially-Carcinogenic, Arginine-Based Heterocyclic Amines, Victoria S. Kim

Honors Theses

Heterocyclic amines (HCAs) are carcinogenic molecules generated from the reaction of creatin(in)e and amino acids at high cooking temperatures in meat. Previous research has shown that replacing creatine with arginine leads to new, uncharacterized HCA molecules. This research entails implementing and optimizing the preparative HPLC analysis of extracts from multiple burnings of arginine with phenylalanine. Isolated fractions from the prep-HPLC analysis were further analyzed using the Ames test to identify mutagenic compounds. Prep-HPLC provides quality control to the burning process along with isolation of larger quantities of materials for further characterization and molecular structure identification.

Copper Nanowires Synthesis And Self-Assembly For Interconnect Applications, Srikar Rao Darmakkolla

Dissertations and Theses

One-dimensional (1D) nanomaterial self-assembly offers an excellent approach to the fabrication of highly complex nanodevices. Despite considerable effort and research, precisely controlling the orientation and positioning of nanowires (NWs) on a large-scale area and assembling into a functional device is still a state of the art problem. This thesis focuses on the dimensionally controlled copper nanowires (Cu NWs) synthesis, and magnetic field assisted self-assembly of cupronickel nanowires (Cu/Ni NWs) into interconnect structures on a carbon doped silicon dioxide (CDO) wafer.

CDO is a low dielectric constant (k) material used for copper interconnects in multilayered complex integrated circuits (ICs). …

Investigation Of Aerosol Optical And Chemical Properties Using Humidity Controlled Cavity Ring-Down Spectroscopy, Xijing Zhu

Dissertations and Theses

Scientists have been observing a change in the climate since the beginning of the 20^th century that cannot be attributed to any of the natural influences of the past. Natural and anthropogenic substances and processes perturb the Earth's energy budget, contributing to climate change. In particular, aerosols (particles suspended in air) have long been recognized to be important in processes throughout the atmosphere that affect climate. They directly influence the radiative balance of the Earth's atmosphere, affect cloud formation and properties, and are also key air pollutants that contribute to a variety of respiratory and cardiovascular diseases. Despite their …

Development Of High-Performing Polydimethylsiloxane-Based Membranes For Carbon Dioxide Separation, Tao Hong

Doctoral Dissertations

Membrane separation is highlighted as one of the most promising approaches to mitigate the excessive CO₂ [carbon dioxide] emission, due to its significant reduction of energy cost compared with many conventional separation techniques. Unfortunately, the separation performance of current membranes does not meet the practical CO₂/N₂ [nitrogen] separation requirements. And due to the huge volume of industrial flue gas, membranes with exceptionally high permeability are needed for practical reasons.

Currently, the separation mechanism of most polymeric membranes is based on size-sieving. However, this method is not sufficient for CO₂/N₂ separations due to the …

An Exploration Of Basic Processes For Aqueous Electrochemical Production Of Hydrogen From Biomass Derived Molecules, Brian Fane

Doctoral Dissertations

Polymer electrolyte membrane fuel cells(PEMFCs) are energy conversion devices with significant potential. The factors preventing them from becoming widespread concern production and distribution of hydrogen. Developing an efficient hydrogen infrastructure with an approachable rollout plan is an essential step towards the future of fuel cells. Water electrolysis is limited by the thermodynamics of the process, which leads to high electrical consumption and significant materials challenges. Alternative methods for cleanly generating hydrogen while using a lower cell voltage are required. PEM based electrolyzers can operate with a "depolarized anode", whereby they become significantly less power hungry.

This thesis explores two techniques …

Design And Synthesis Of Analogs Of Myo-Inositol, Serine, And Cysteine To Enable Chemical Biology Studies, Tanei J. Ricks

Doctoral Dissertations

Phosphorylated myo-inositol compounds including inositol phosphates (InsPs) as well as the phosphatidylinositol polyphosphate lipids (PIP_ns) are critical biomolecules that regulate many of the most important biological processes and pathways. They are aberrant in many disease states due to their regulatory function. The same is true of the phospholipid phosphatidylserine (PS) which can serve as a marker to begin apoptosis. However, the full scope of activities of these structures is not clear, particularly since techniques that enable global detection and analysis of the production of these compounds spatially and temporally are lacking. With all of these obstacles in …

Multiscale Modeling Approach To Understand Active Sites In Non-Conventional Catalyst Layers For Fuel Cell Applications, Diana Constanza Orozco Gallo

Doctoral Dissertations

Fuel cells development required stable, active and more abundant catalytic materials. Oxygen reduction reaction (ORR) is the key process to enhance better activity and reduce the fabrication costs. Pt-based has proven to be the best catalyst for ORR and greater efforts has been made in terms of reducing the Pt content in the electrodes, reduce electrode thickness and enhance better catalytic activities. To overcome many of the challenges present, the catalyst layer studies are the great importance in the fuel cell community. Understanding catalyst layer with new catalytic materials, and configurations requires the development of methodological approach to relate structure, …

Development And Implementation Of Redox-Active Olefin Polymerization Catalysts, William Curtis Anderson Jr.

Doctoral Dissertations

Investigating homogeneous polymerization catalysts has been a thriving area of chemistry in the academic realm for several decades now, and has helped drive the development of a range of materials, from designer plastics to cheap commodity polymers. Billions of pounds of these materials are produced every year, which ensures that continuing research in the area will be necessary to improve current processes and enable more economic use of our resources.

This dissertation showcases the Long group’s research in homogeneous polymerization catalysis and our impact on the field thus far. We show that intelligent design of redox-active catalysts allows for a …

Analysis Of Primary Stripper Foils At The Spallation Neutron Source By An Electron Beam Foil Test Stand, Eric Paul Barrowclough

Doctoral Dissertations

Diamond films are used at the Spallation Neutron Source (SNS) as the primary charge exchange foils (i.e., stripper foils) of the accelerated 1 GeV (Gigaelectron volts) hydride ions. The most common type of film used is a nanocrystalline diamond film, typically 17 mm x 45 mm (millimeter) with an aerial density of 350 μg/cm² (microgram per square centimeter). The diamond film is deposited on a corrugated silicon substrate using plasma-assisted chemical vapor deposition. After the growth of the diamond film, 30 mm of the silicon substrate is etched away, leaving a freestanding diamond foil with a silicon handle that …

Development Of An Improved Synthesis Of S-D-Ribosyl-L-Homocysteine (Srh) And Progress Toward Srh Analogs Modified At The C3 Position, Emily Rouse

Master's Theses

Quorum sensing is a system that facilitates bacteria turning on and off gene expression depending on population density. System 2 quorum sensing is utilized by both Gram positive and Gram negative bacteria, and the quorum sensing molecule used in this system is AI-2. AI-2 is biosynthesized by the enzyme LuxS from the precursor SRH. This thesis describes an improved synthesis of SRH through the exploration of different protecting group strategies. The knowledge gained from the improved synthesis of SRH is then applied toward the synthesis of SRH analogues with increased steric bulk installed through use of a stereoselective anti-Mannich reaction. …

Integration Of Scale-Themed Instruction Across The General Chemistry Curriculum And Selected In-Depth Studies, Jaclyn Trate

Theses and Dissertations

In 1982, in response to a growing demand for a scientifically literate population, two organizations, the AAAS and NCISE published reports that proposed using themes to bridge scientific disciplines1,2. The NCISE report identified “9 explanatory concepts” which included organization, cause and effect, systems, scale, models, change, structure or function, discontinuous and continuous properties, and diversity. The AAAS report, as part of Project 2061, identified 4 themes that define science literacy which included systems, models, constancy and change, and scale. In 1993, the AAAS released the Benchmarks for Science Literacy3 which outlined what all students should know or be able to …

Investigation Of Tribochemical Reactions Using The Model System Of Methyl Thiolate On Copper Foil In Ultrahigh Vacuum And Ab-Initio Calculations, Heather Loren Adams

Theses and Dissertations

Advancement in the understanding of tribochemical systems suffers from several obstacles that hinder the progress in advancing an understanding of the fundamental processes involved in the evolution of friction and wear. Characterizing ephemeral chemical states within a buried interface is an experimental challenge and work in this dissertation uses a model system, methyl thiolate on copper foil, that undergoes tribo-activated decomposition to investigate the rate of change of the chemical components in the interface. The elementary steps in the tribochemical reaction were identified and consist of a shear-induced decomposition of methyl thiolate species to produce gas-phase hydrocarbons and form surface …

Study Of 2,5-Diaminoimidazolone, A Mutagenic Product Of Oxidation Of Guanine In Dna, Hannah Catherine J. Pollard

Electronic Theses and Dissertations

2,5-diaminoimidazolone (Iz) is an important product of a 4-electron oxidation of guanine. The present research focuses on the mechanisms of formation of Iz via pathways initiated by guanine oxidation by one-electron oxidants (OEOs) generated by X-ray radiolysis in aqueous solutions. The kinetics of formation and yields of Iz in reactions of native highly polymerized DNA with different OEOs have been compared using an HPLC-based quantitative analysis of low-molecular products generated from the reaction of DNA-bound Iz with primary amines. Mechanisms of Iz formation in DNA have been investigated including oxygen and superoxide dependence as well as the hypothesis that 8-oxo-G, …

Apan Production Through Photooxidation Of Isoprene In The Presence Of NoX, Timothy Glidewell

Masters Theses

Peroxyacyl nitrates (PANs, RC(O)OONO₂) are of great importance in atmospheric chemistry. They act as transporters of reactive nitrogen, and radical delivery agents. There are no known natural emission sources of PANs; they are produced through reaction of volatile organic compounds (VOCs) and nitrogen oxides (NO_x) in the atmosphere.

VOCs can enter the atmosphere through biogenic and anthropogenic pathways. It has been estimated that isoprene makes up 70% of the biogenic VOCs (BVOCs) emitted annually. Isoprene has been shown to impact ozone levels in both rural and urban areas by sequestering and transporting NO_x in the form …

Mechanistic Studies Of The Iron And Molybdenum Nitrogenases, Derek Harris

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As a basic building block in many biological molecules the element nitrogen (N) is essential for life. Dinitrogen (N2) is abundant in Earth’s atmosphere, but this form is biologically unavailable. To be biologically available N2 must undergo an energy demanding reduction reaction to the fixed form, ammonia (NH3). The industrial Haber-Bosch process, which accounts for approximately 50% of the worlds fixed nitrogen, uses energy from fossil fuels to achieve high pressures and temperatures to facilitate the reaction. The energy used by Haber-Bosch accounts for approximately 2% of the world’s annual supply. The remainder of fixed nitrogen is produced biologically by …

Water Chemistry Dynamics In Four Vernal Pools In Maine, Usa, Lydia H. Kifner

Electronic Theses and Dissertations

Vernal pools are small seasonal wetlands that are a common landscape feature that contribute to biodiversity in northeastern North American forests. However, even basic information about their biogeochemical functions, such as carbon cycling, is limited. Dissolved gas concentrations (CH₄, CO₂) and other water chemistry parameters were monitored weekly at the bottom and surface of four vernal pools in central and eastern Maine, USA, from April to August 2016. The vernal pools were supersaturated with respect to CH₄ and CO₂ at all sampling dates and locations. Concentrations of dissolved CH₄ and CO₂ ranged …

Green Chemistry Oxidative Modification Of Peptoids Utilizing Bleach And Tempo, Jesse Leland Roberts

Graduate Theses and Dissertations

Biotherapeutic drugs, derived from biological molecules such as proteins and DNA, are becoming an integral and exceptionally critical aspect of modern medicine. Compared to common pharmaceutical drugs, biotherapeutics are much larger in size and have greater target specificity, allowing them to treat many chronic diseases ranging from cancer to rheumatoid arthritis. The major issue with protein based therapeutics is that they readily undergo proteolysis, or enzymatic degradation, when administered through subcutaneous injections. Traditionally, biotherapeutic modification procedures have centered on the use of PEG derivatives. This process, called PEGylation, is unfavorable due to the increases in molecular weights of the proteins …

Short Synthesis And Biological Evaluation Of 5-Chloro-7-Benzoyl 2,3-Dihydrobenzo[B]Furan -3-Carboxylic Acid(Brl-37959) And Its Analogs., Shamsul Arefin Ahmed

Theses and Dissertations

The synthesis of BRL-37959 has previously been reported. As an NSAID, the compound was tested for and found that it had very low gastric irritancy. Commercially available NSAIDs are non-selective COX inhibitors that enhance the risk of gastric, duodenal mucosal injury or erosions and ulcer problems as well as lead to nephrotoxicity. The COX-2 selective inhibitor Celecoxib (Celebrex) increases the risk of serious cardiovascular (CV) thrombotic events, myocardial infarction and stroke as well as increased nephrotoxicity. COX inhibitors are active against inflammation, pain, fever and different types of cancers. Considering the enormous potential benefits and side effects of non-selective COX …