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Articles 1 - 17 of 17
Full-Text Articles in Physical Sciences and Mathematics
Investigation Of A Novel Method For Polonium-210 Determination In Groundwater, Tara Matheny
Investigation Of A Novel Method For Polonium-210 Determination In Groundwater, Tara Matheny
All Theses
A novel method was investigated for the quantification of 210Po in water as an alternative to the standard method of spontaneous plating onto Ag disks followed by quantification with an alpha spectrometer. The novel method concentrated a 0.5L sample by MnO2 co-precipitation followed by dissolution of the precipitate into a solution. Polonium-210 was separated from the solution and quantified in a column containing a 50:50 by volume mixture of Pb resin (Eichrom Technologies, Inc.) mixed with granulated CaF2:Eu scintillator. The column containing 210Po is quantified on a liquid scintillation counter without the introduction of liquid cocktail. The minimum detectable concentration …
Prevention Of Iron- And Copper-Mediated Oxidative Dna Damage By Neurotransmmitters And Related Compounds: Evidence For Metal Binding As An Antioxidant Mechanism, Carla Garcia
All Theses
An array of health concerns have been attributed to oxidative DNA damage from the hydroxyl radical (*OH), and the presence of the most biologically available metals iron and copper perpetuate the production of this radical through the Fenton and Fenton-like reactions, respectively. The concentrations at which flavonol and polyphenol antioxidants prevent 50% of DNA damage (IC50) were measured using gel electrophoresis assays upon Fe(II)/H2O2- and Cu(I)/H2O2-mediated DNA damage (Chapter 2). Results show that catechol- and gallol-containing antioxidants differ greatly in preventing DNA damage by Cu(I)/H2O2, compared to Fe(II)/H2O2, behavior that was explained using electron paramagnetic resonance spectroscopy. Semiquinone and other …
Electrolyte Incorporation Into Composite Electrodes For Proton-Exchange Membrane Fuel Cells And Lithium-Ion Batteries, Jung Oh
All Dissertations
This dissertation describes research on the preparation and characterization of composite electrodes for use in proton-exchange membrane (PEM) fuel cells and lithium ion batteries. The general focus of the research was on high-surface-area carbon supports for platinum catalysts in fuel cells, and integration of electrolytes, particularly fluoropolymer electrolytes, into composite electrodes both batteries and fuel cells. Results are described for work in the following three specific topical areas.
1. Carbon nanofibers for use as platinum (Pt) catalyst supports in fuel cells were prepared by carbonization of electrospun acrylic fibers. The resulting carbon nanofibers were found to contain mainly micropores. Following …
Single Particle And Ensemble Spectroscopy Of Conjugated Polymer Nanoparticles And Their Development For Photodynamic Therapy, Jennifer Grimland
Single Particle And Ensemble Spectroscopy Of Conjugated Polymer Nanoparticles And Their Development For Photodynamic Therapy, Jennifer Grimland
All Dissertations
Energy transport in conjugated polymers is the combination of energy transfer and exciton diffusion. There is considerable ongoing research in this field, converging to develop better organic photovoltaics, polymer light emitting diodes (PLEDs) and organic solar cells, to name a few. One way these phenomena can be explored is by doing solution dependent studies on conjugated polymer nanoparticles. With experiments on CP dots in an aqueous solution and the addition of a water miscible organic solvent in varying concentrations, dynamics occurring in the folding process can be better understood, and also exciton and fluorescence quenching properties can be extracted as …
Modification And Characterization Of Fluorescent Conjugated Polymer Nanoparticles For Single Molecule Detection, Yueli Zheng
Modification And Characterization Of Fluorescent Conjugated Polymer Nanoparticles For Single Molecule Detection, Yueli Zheng
All Dissertations
Single molecule tracking using fluorescent dye or nanoparticle labels has emerged as a useful technique for probing biomolecular processes. Considerable interest arises in the development of nanoparticle labels with brighter fluorescence in order to improve the spatial and temporal resolution of single molecule detection and to facilitate the application of single molecule detection methods to a wider range of intracellular processes. The McNeill laboratory recently reported that conjugated polymer nanoparticles exhibit fluorescence cross-sections roughly 10-100 times higher than other luminescent nanoparticles of similar size, excellent photostability (2.2×108 photons emitted per nanoparticle prior to photobleaching), and saturated emission rates roughly 100 …
Semifluorinated Aromatic Ether Polymers Segmented With Polyethylene Glycol (Peg), Dakarai Brown
Semifluorinated Aromatic Ether Polymers Segmented With Polyethylene Glycol (Peg), Dakarai Brown
All Dissertations
Aromatic trifluorovinyl ether (TFVE) monomers are the precursors for perfluorocyclobutyl (PFCB) aryl ether polymers and fluoroethylene/vinylene alkyl/aryl ether (FAE) polymers. PFCB aryl ether polymers are prepared by 2π + 2π cycloaddition of aromatic TFVE monomers. FAE polymers are prepared by nucleophilic addition of dual functional aryl or alkyl alcohols to aryl TFVE monomers. PFCB aryl ether and FAE polymers are amorphous, have excellent processability, high thermal stability, optical clarity, and tunability using a variety of (co)monomers. In this dissertation several novel monomers, polymers, and blends were prepared by incorporation of polyethylene glycol (PEG) or PEG precursors.
Chapter 1 contains the …
A Theoretical Investigation Examining Dna Conformational Changes And Their Effects On Glycosylase Function, Allyn Brice
A Theoretical Investigation Examining Dna Conformational Changes And Their Effects On Glycosylase Function, Allyn Brice
All Dissertations
Glycosylase enzymes initiate the process of base excision repair (BER) in order to prevent the irreversible modification of the genome. In the BER process a damaged DNA base is recognized, removed from the DNA sequence, and then the remaining abasic site is repaired. Glycosylase enzymes are responsible for the base recognition mechanism and catalysis of the base excision. One of the most studied glycosylase superfamilies is uracil DNA glycosylase (UDG). The UDG superfamily has demonstrated specificity for excising uracil, which is the deamination product of cytosine, from DNA sequences of prokaryotes and eukaryotes. Mismatch-specific uracil DNA glycosylase (MUG) is a …
Bridging The Gap Between Structures And Properties: An Investigation And Evaluation Of Students' Representational Competence, Sonia Underwood
Bridging The Gap Between Structures And Properties: An Investigation And Evaluation Of Students' Representational Competence, Sonia Underwood
All Dissertations
The heart of learning chemistry is the ability to connect a compound's structure to its function; Lewis structures provide an essential link in this process. In many cases, their construction is taught using an algorithmic approach, containing a set of step-by-step rules. We believe that this approach is in direct conflict with the precepts of meaningful learning. From a sequential, mixed methods study, we found that students have much difficulty constructing these structures and that the step-by-step rules do not make use of students' relevant prior knowledge. This causes students to develop 'home grown' rules when unsure of how to …
An Investigation Of The Effectiveness Of Gestures To Enhance Concept Retention In Chemistry Instruction, Jeffrey Lamb
An Investigation Of The Effectiveness Of Gestures To Enhance Concept Retention In Chemistry Instruction, Jeffrey Lamb
All Theses
The emergence of embodied cognition as a theory of learning has placed new emphasis on the interdependent relationship between what the mind perceives and what the body experiences. Movement and objects in the physical environment take on significant roles in the process of learning within this view and the role of gesturing in cognition has become increasingly interesting. Significant research suggests that the physical process of gesturing is connected to how the mind processes information. Gesturing during the recall of information is a universally known phenomena and one that seems to aid in the process of recall. More recent findings …
Conjugated Polymers And Inter-Chromophore Interactions: Synthesis, Photophysical Characterization And Application, Anshuman Mangalum
Conjugated Polymers And Inter-Chromophore Interactions: Synthesis, Photophysical Characterization And Application, Anshuman Mangalum
All Dissertations
Ever since the discovery of conducting polymers (CPs)in the late 1970s, organic conjugated materials and polymers is one of the most popular and fascinating research area among the scientists due to the remarkably unique properties and broad range of applications of (CPs), notably organic photovoltaic (OPVs), organic or polymer based light emitting devices (OLEDs / PLEDs), field effect transistors (FETs), nonlinear optical (NLO) devices and sensor for biologically relevant analytes, metal ions and anions. Optical properties of these materials depend on intra / interchromophoric interaction, geometry and relative orientation in space. Detailed study of such materials can also help us …
Particle Beam Glow Discharge Spectroscopy As A Tool For Speciation And Metallomics Analysis, Charles Quarles Jr
Particle Beam Glow Discharge Spectroscopy As A Tool For Speciation And Metallomics Analysis, Charles Quarles Jr
All Dissertations
Metallomics is a growing field of interdisciplinary research that investigates metals in biological and environmental systems. One of the major problems in detecting metals in biological systems is the instrumentation required to analyze these complex biological samples. Typically, an inductively coupled plasma-optical emission spectrometer or -mass spectrometer (ICP - OES or - MS) is used for elemental analysis and an electrospray ionization-mass spectrometer (ESI-MS) is used for molecular information. In almost all cases, the sample introduction matrix is different for each instrument, which can affect the physiological conditions of the sample and change its properties. Particle beam/hollow cathode-optical emission spectroscopy …
Synthesis, Characterization, And Reactivity Of Biologically Relevant Copper(I) Selone And Thione Complexes, Martin Kimani
Synthesis, Characterization, And Reactivity Of Biologically Relevant Copper(I) Selone And Thione Complexes, Martin Kimani
All Dissertations
In Fenton-like reactions, Cu+ localized on DNA reduces hydrogen peroxide to form hydroxyl radical (*OH), resulting in oxidative DNA damage. This DNA damage causes mutation and cell death, which can lead to diseases such as cancer, Alzheimer's, and arteriosclerosis. Sulfur and selenium antioxidants have been investigated for the prevention and treatment of these diseases, and studies have shown that sulfur- and selenium-containing antioxidants prevent DNA damage from copper-generated hydroxyl radical and that metal coordination is required for the observed antioxidant activity.
To determine how copper coordination results in DNA damage inhibition, Cu+ complexes with selone and thione ligands were synthesized …
Targeting A-Form Nucleic Acids: A Neomycin Based Approach, Nicholas Shaw
Targeting A-Form Nucleic Acids: A Neomycin Based Approach, Nicholas Shaw
All Dissertations
This manuscript reflects our most recent advancements in the recognition of nucleic acids. Chapter one focuses on previously established methods in nucleic acid recognition. Nucleic acid targeting by small molecules affords a unique way to potentially inhibit biological functions, which is different from targeting enzyme and protein bio-macromolecules. We seek to further develop an aminoglycoside approach to targeting nucleic acids. Since aminoglycosides were first introduced, over 60 years ago, as treatment for tuberculosis, natural product discovery and demands for therapeutically more effective aminoglycosides, with lowered toxicity, have dominated the landscape of aminoglycoside research. More recently, our group has established neomycin …
Synthesis And Characterization Of Extended Solids Containing Nano-Sized Transition Metal Oxide Lattices, Matthew Williams
Synthesis And Characterization Of Extended Solids Containing Nano-Sized Transition Metal Oxide Lattices, Matthew Williams
All Dissertations
In this research, focus has been placed on the study of magnetic anomalies due to geometric frustration of magnetic ions. The goal of the study presented in this dissertation was to synthesize pseudo&ndashlow&ndashdimensional (PLD) compounds, those structures showing zero (dot), one (chain), and two (sheet) dimensional lattices observed in extended (3D) host frameworks with enhanced anisotropic physical properties, in an attempt to elucidate some structure&ndashproperty correlations arising from magnetic spin confinement. The scope of this research involved 1) exploratory synthesis of novel, low&ndashdimensional transition metal oxide lattices, specifically Mn and V, embedded in non&ndashmagnetic oxyanion frameworks, either Ge, P, or …
Incorporation Of Novel Diphosphines Into Polymer Structure For Light Absorption And Emission Applications, Thora Maltais
Incorporation Of Novel Diphosphines Into Polymer Structure For Light Absorption And Emission Applications, Thora Maltais
All Theses
In today's society, there is a constant need for the development and production of new and improved technology, especially in the development of light emitting diodes for screens in electronic devices, and photovoltaic cells as sources for alternative energy. New insights for the development of such technology can be elucidated through the incorporation of chromophoric diphosphines into phosphonium and platinum(II) polymer frameworks. From diphosphine incorporation, it will be shown that polymer properties can be enhanced for such applications by invoking phosphorescence, and providing a modular platform for generating multilayer polymer films that provide intriguing energy transfer capabilities in the visible …
Assessment Of Conceptual Understanding Of Atomic Structure, Covalent Bonding, And Bond Energy, Alma Gonzales
Assessment Of Conceptual Understanding Of Atomic Structure, Covalent Bonding, And Bond Energy, Alma Gonzales
All Theses
This research work relied upon the importance of conceptual understanding to meaningful learning. Conceptual understanding is strongly influenced by students' prior knowledge (1). Many of these ideas pose strong barriers to deeper understanding and are called misconceptions since they are inconsistent or in conflict with generally accepted scientific facts (2). Thus, it is beneficial for instructors to initially elicit students' conceptual understanding in order to properly address student's misconceptions during the learning process. However, results are very dependent on the instrument used to elicit conceptual understanding (3). The most commonly used tools are summative assessments or achievement tests (4). They …
Uranyl Reactions With Dithionite, L-Ascorbic Acid, And Supported Nanosized Zero-Valent Iron, Shanna Estes
Uranyl Reactions With Dithionite, L-Ascorbic Acid, And Supported Nanosized Zero-Valent Iron, Shanna Estes
All Theses
This work examined several reductants for remediation of low pH aqueous uranium contamination by reductive precipitation. Reductants included sodium dithionite, L-ascorbic acid, and nanosized zero-valent iron (nZVI). Additionally, the reductive capacity of nZVI successfully entrapped within a silicate matrix (cryogel) was also examined. This supported nZVI is expected to increase nZVI stability in the subsurface, and to provide a convenient in situ delivery mechanism for other remediation systems which may combine entrapped reductant and catalyst.
Fluorescence and absorbance spectroscopy were used to investigate the interaction between hexavalent uranium (U(VI), uranyl) and both sodium dithionite and L-ascorbic acid at pH 2. …