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Articles 1 - 16 of 16
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Gold Nanoparticle Generation Using In Situ Reduction On A Photoresist Polymer Substrate, Christopher J. Clukay
Gold Nanoparticle Generation Using In Situ Reduction On A Photoresist Polymer Substrate, Christopher J. Clukay
HIM 1990-2015
This report presents evidence that in-situ reduction of metal ions bound to a cross-linked polymer surface does not always result in nanoparticle formation solely at the interface, as is commonly assumed, but also as much as 40 nm deep within the polymer matrix. Tetrachloroaurate ions were bound using a variety of multi-functional amines to cured films of SU-8 -- a cross-linkable epoxide frequently used for micro- and nanofabrication -- and then treated using one of several reducing agents. The resulting gold-nanoparticle decorated films were examined by X-ray photoelectron spectroscopy and by plan-view and cross-sectional transmission electron microscopy. Reduction using sodium …
Characterization Of Composite Broad Band Absorbing Conjugated Polymer Nanoparticles Using Steady-State, Time-Resolve And Single Particle Spectroscopy, Maxwell Scotland Bonner
Characterization Of Composite Broad Band Absorbing Conjugated Polymer Nanoparticles Using Steady-State, Time-Resolve And Single Particle Spectroscopy, Maxwell Scotland Bonner
Electronic Theses and Dissertations
As the global economy searches for reliable, inexpensive and environmentally friendly renewable energy resources, energy conservation by means of photovoltaics has seen near exponential growth in the last decade. Compared to state-of-the-art inorganic solar cells, organic photovoltaics (OPVs) composed of conjugated polymers are particularly interesting because of their processability, flexibility and the potential for large area devices at a reduced fabrication cost. It has been extensively documented that the interchain and intrachain interactions of conjugated polymers complicate the fundamental understanding of the optical and electronic properties in the solid-state (i.e. thin film active layer). These interactions are highly dependent on …
Density Functional Theory Study Of Molecules And Crystals Containing D And F Metals, Shruba Gangopadhyay
Density Functional Theory Study Of Molecules And Crystals Containing D And F Metals, Shruba Gangopadhyay
Electronic Theses and Dissertations
Density Functional Theory (DFT) method is applied to study the crystal structure of transition metal and lanthanide oxides, as well as molecular magnetic complexes. DFT is a widely popular computational approach because it recasts a many-body problem of interacting electrons into an equivalent problem of non-interacting electrons, greatly reducing computational cost. We show that for certain structural properties like phase stability, lattice parameter and oxygen migration energetics pure DFT can give good agreement with experiments. But moving to more sensitive properties like spin state energetic certain modifications of standard DFT are needed. First we investigated mixed ionic-electronic conducting perovskite type …
Self-Assembly And Photophysics Of Selected Organic Materials And Two-Photon Bioimaging With Profluorescent Nitroxides, Polyelectrolyte Nanoparticles, And Squaraine Probes, Hyo Yang Ahn
Electronic Theses and Dissertations
Two-photon absorption and upconverted fluorescence has been utilized in a variety of applications in pure science and engineering. Multiphoton-based techniques were used in this research in order to understand photophysical and chemical characteristics of several fluorescent dyes and to demonstrate some of their key applications. Two-photon fluorescence microscopy (2PFM) has become a powerful technique in bio-photonics for non-invasive imaging in the near-infrared (NIR) region (700~1000 nm) that often results in less photobleaching. In Chapter 1, there is a brief introduction to fluorescence, examples of fluorescence materials, and a discussion of the advantages of two-photon absorption. 2PFM imaging was utilized in …
Two-Photon Cross Section Enhancement Of Photochromic Compounds For Use In 3d Optical Data Storage, Gheorghe Luchita
Two-Photon Cross Section Enhancement Of Photochromic Compounds For Use In 3d Optical Data Storage, Gheorghe Luchita
Electronic Theses and Dissertations
Rewritable photochrome-based 3D optical data storage requires photochromic molecules with high two-photon absorption (2PA) cross sections. Currently, the low value of two-photon absorption cross sections of existing photochromes makes them unsuitable for practical application in 3D data storage. Worldwide attempts to increase the cross section of photochromic molecules by altering the chemical structure have yielded poor results. In this work, two ways to increase the two-photon absorption cross sections of photochromes were investigated. In the first method, partial success demonstrated by extending the conjugation of a photochromic molecule, a high two-photon absorption cross section of the closed form isomer and …
Self-Assembly Of Squaraine Dyes, Maher A. Qaddoura
Self-Assembly Of Squaraine Dyes, Maher A. Qaddoura
Electronic Theses and Dissertations
Squaraine dyes have been a subject of extensive investigations lately due to their wide applications in important technological fields such as bioimaging probes, bioconjucation, second generation photosensitizers for photodynamic therapy, second harmonic generating organic dyes, two-photon absorbing materials with large cross section values, and, finally, photoconducting materials in photovoltaic cells. While a large number of patents and papers has been produced regarding their applications limited work has been done concerning their thermotropic behavior, including their liquid crystalline properties, or correlation of the crystalline structure to both the solid state aggregation and their photophysical properties. In the first chapter of this …
The Application Of Two-Photon Absorbing Probes In Lysosomal, Zinc Ion Sensing And Folate Receptor-Targeted Bioimaging, Xuhua Wang
Electronic Theses and Dissertations
Two-photon fluorescence microscopy (2PFM) has become a powerful technique for bioimaging in non-invasive cancer diagnosis and also investigating the mechanization and original of a variety of diseases by tracking various biological processes. Because the fluorescence emission by two photon absorbing (2PA) is directly proportional to the square of the intensity of excitation light, this intrinsic property of 2PA provides 2PFM great advantages over traditional one-photon fluorescence microscopy (1PFM), including high 3D spatial localization, less photodamage and interference from biological tissue because of using longer wavelength excitation (700-1300 nm). However, most 2PA probes are hydrophobic and their photostabilities are questionable, severely …
The Application Of Chemometrics To The Detection And Classification Of Ignitable Liquids In Fire Debris Using The Total Ion Spectrum, Jennifer N. Lewis
The Application Of Chemometrics To The Detection And Classification Of Ignitable Liquids In Fire Debris Using The Total Ion Spectrum, Jennifer N. Lewis
Electronic Theses and Dissertations
Current methods in ignitable liquid identification and classification from fire debris rely on pattern recognition of ignitable liquids in total ion chromatograms, extracted ion profiles, and target compound comparisons, as described in American Standards for Testing and Materials E1618-10. The total ion spectra method takes advantage of the reproducibility among sample spectra from the same American Society for Testing and Materials class. It is a method that is independent of the chromatographic conditions that affect retention times of target compounds, thus aiding in the use of computer-based library searching techniques. The total ion spectrum was obtained by summing the ion …
Photo Retro Diels-Alder Reaction Of The Adducts Of Tetracyanoethylene And Polyaromatic Compounds, Siddthartha Banerjee
Photo Retro Diels-Alder Reaction Of The Adducts Of Tetracyanoethylene And Polyaromatic Compounds, Siddthartha Banerjee
Electronic Theses and Dissertations
Thermally induced retro-Diels Alder (rDA) reaction has been extensively used for the preparation of many reactive intermediates in organic synthesis. But the uses of photo-retro Diels-Alder (PrDA) reaction in organic synthesis were sparingly reported in literature. Due to its spatial and temporal control, PrDA can be used in making of photosensitive materials, in drug delivery and also for mechanistic studies. Diels-Alder adducts of tetracyanoethylene (TCNE) and polyaromatic compounds (anthracene, napthacene, pentacene and phencyclone) were synthesized and were subjected to PrDA reaction through 254-nm irradiation. The quantum yield and the consequent photoreactivity of these DA adducts follow the following order. TCNE/naphthacene …
The Study Of Three Different Layered Structures As Model Systems For Hydrogen Storage Materials, Muzaffer Tonguç Öztek
The Study Of Three Different Layered Structures As Model Systems For Hydrogen Storage Materials, Muzaffer Tonguç Öztek
Electronic Theses and Dissertations
The strength and success of the hydrogen economy relies heavily on the storage of hydrogen. Storage systems in which hydrogen is sequestered in a solid material have been shown to be advantageous over storage of hydrogen as a liquid or compressed gas. Many different types of materials have been investigated, yet the desired capacity and uptake/release characteristics required for implementation have not been reached. In this work, porphyrin aggregates were investigated as a new type of material for hydrogen storage. The building blocks of the aggregates are porphyrin molecules that are planar and can assume a face to face arrangement …
An Evaluation Study Of The Effectiveness Of Using A Reaction-Based Process For Hydrazine Waste Remediation, Cristina M. Oropeza
An Evaluation Study Of The Effectiveness Of Using A Reaction-Based Process For Hydrazine Waste Remediation, Cristina M. Oropeza
Electronic Theses and Dissertations
Hydrazine (HZ) and monomethylhydrazine (MMH) are used extensively as hypergolic propellants at Kennedy Space Center. These highly reactive fuels are considered highly toxic, and potentially carcinogenic. Consequently, the transport, handling, and disposal of hydrazines is strictly regulated to protect personnel and the environment. Currently, KSC generates large volumes of hydrazine-laden wastewater for disposal. This waste is contained and shipped on public highways for subsequent disposal by incineration presenting a potentially catastrophic threat to the environment and the general public in the event of an accidental release. Other existing remediation methods include oxidative and reductive pathways as well as biodegradation in …
Comparative Study Of Ethanol And Methanol Electro-Oxidation On A Platinum/Ceria Composite Electrode In Alkaline And Acid Solutions : Electro-Catalytic Performance And Reaction Kinetics, Carlos Humberto Hidalgo Martinez
Comparative Study Of Ethanol And Methanol Electro-Oxidation On A Platinum/Ceria Composite Electrode In Alkaline And Acid Solutions : Electro-Catalytic Performance And Reaction Kinetics, Carlos Humberto Hidalgo Martinez
Electronic Theses and Dissertations
A comparative study of the electro-oxidation of ethanol and methanol was carried out on a Pt/ceria composite electrode prepared by electro-deposition. Modification of the Pt electrode was realized by co-deposition from a 1.0 mM K₂PtCl₆ solution that also contained a 20 mM suspension of ceria. The electro-catalytic activities and stabilities of the Pt/ceria catalyst towards ethanol electro-oxidation reactions (EOR) and methanol electro-oxidation reactions (MOR) were investigated by potentiodynamic and potentiostatic methods in 0.5 M sulfuric acid and 1.0 M sodium hydroxide solutions at various concentrations of ethanol and methanol. The kinetics of ethanol and methanol on a Pt/ceria composite electrode …
Investigations On Morphology, Spectroscopy And Near-Infrared Photoresponse Sensitization Of Conjugated Polymers In Organic Photovoltaics, Zhongjian Hu
Electronic Theses and Dissertations
Conjugated polymer architecture and morphology are two of the key factors that determine corresponding opto-electronic device performance. It is well-known that conjugated polymers display a variety of conformations and exhibit aggregation in their materials and even for individual polymer chains. The intrinsic structural heterogeneity of conjugated polymers strongly complicates the active layer morphology and phase separation, which are crucial for photoinduced charge generation and transport in polymer based bulk heterojunction-organic photovoltaics device (BHJ-OPVs). Aiming to probe the molecular level correlations between conjugated polymer architecture, morphology and optoelectronic properties, single molecule spectroscopy (SMS) and single particle spectroscopy (SPS) were employed. The …
Investigation Of Nanoceria-Modified Platinum-Gold Composite Electrodes For The Electrochemical Reduction Of Oxygen In Alkaline Media, Rahul Hegishte
Investigation Of Nanoceria-Modified Platinum-Gold Composite Electrodes For The Electrochemical Reduction Of Oxygen In Alkaline Media, Rahul Hegishte
Electronic Theses and Dissertations
Platinum-gold and nanoceria-modified platinum-gold electrodes were prepared on a platinum surface via electrochemical reduction of solutions of platinum and gold salts in the dispersion of nanoceria. The molar ratios of Pt and Au were varied in both PtAu and PtAu/CeO₂ electrodes while the total concentration of the metals was maintained at 2 x 10⁻³M and the concentration of nanoceria was maintained constant at 5 x 10⁻³M. The electrodes were characterized by their cyclic voltammetry curves in 0.5M sulfuric acid solution. The electrochemically active area of the electrodes was determined using the copper underpotential deposition method. The linear sweep voltammograms of …
Self-Assembly Of Amyloid Aggregates Simulated With Molecular Dynamics, Workalemahu Mikre Berhanu
Self-Assembly Of Amyloid Aggregates Simulated With Molecular Dynamics, Workalemahu Mikre Berhanu
Electronic Theses and Dissertations
Amyloids are highly ordered cross-β sheet aggregates that are associated with many diseases such as Alzheimer‟s, type II diabetes and prion diseases. Recently a progress has been made in structure elucidation, environmental effects and thermodynamic properties of amyloid aggregates. However, detailed understanding of how mutation, packing polymorphism and small organic molecules influence amyloid structure and dynamics is still lacking. Atomistic modeling of these phenomena with molecular dynamics (MD) simulations holds a great promise to bridge this gap. This Thesis describes the results of MD simulations, which provide insight into the effects of mutation, packing polymorphism and molecular inhibitors on amyloid …
The Relative Recoverability Of Dna And Rna Profiles From Forensically Relevant Body Fluid Stains, Charly Parker
The Relative Recoverability Of Dna And Rna Profiles From Forensically Relevant Body Fluid Stains, Charly Parker
Electronic Theses and Dissertations
Biological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in routine forensic casework, RNA of sufficient quantity and quality must be obtained from biological fluid stains and the methods used for …