Current Search: Frazer, Andrew (x)
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- Title
- Synthetic Design and Characterization of Polycyclic Aromatic Compounds in Molecular and Extended System.
- Creator
-
Pour, Gavin, Belfield, Kevin, Frazer, Andrew, Elsheimer, Seth, University of Central Florida
- Abstract / Description
-
The work presented herein focuses on the synthesis and characterization of polycyclic aromatic compounds for a wide variety of toxicological, analytical, and electronic applications. First, the modular synthesis of 12 dibenzo- and naphtho- fluoranthene polycyclic aromatic hydrocarbons (PAHs) via a Pd-catalyzed five-membered ring closing procedure is discussed. By understanding the various modes through which the Pd migrates during transformation, structural rearrangements were bypassed,...
Show moreThe work presented herein focuses on the synthesis and characterization of polycyclic aromatic compounds for a wide variety of toxicological, analytical, and electronic applications. First, the modular synthesis of 12 dibenzo- and naphtho- fluoranthene polycyclic aromatic hydrocarbons (PAHs) via a Pd-catalyzed five-membered ring closing procedure is discussed. By understanding the various modes through which the Pd migrates during transformation, structural rearrangements were bypassed, obtaining regioselectivity through various redesigns in the synthetic route. Each compound in the serious was rigorously characterized via 1D/2D NMR, absorption and emission spectroscopy as well as cyclic voltammetry, which shows vast differences due to small structural changes between these constitutional isomers. Next, a series of polyphenylated organic ligands for zirconium metal organic frameworks is presented as materials for post-synthetic Scholl cyclodehydrogenation. Lastly, a series of organic linkers featuring covalently anchored redox-active pendants is explored for tuneable redox activity in Zr-based metal-organic frameworks. Thin-films were grown onto fluorine-doped tin-oxide glass electrodes and analyzed by cyclic voltammetry. This is the first reported pre-synthetic incorporation of covalently-bound ferrocenyl pendants into such a system. By attenuating the proportions of redox active and inactive links the oxidative peak currents could be tuned. This body of work represents a contribution toward the practical design and synthesis of polycyclic aromatic for a wide variety of analytical and electrochemical applications.
Show less - Date Issued
- 2019
- Identifier
- CFE0007512, ucf:52647
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007512
- Title
- Nanoscale Characterization and Mechanism of Electroless Deposition of Silver Metal.
- Creator
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Grabill, Christopher, Kuebler, Stephen, Beazley, Melanie, Zou, Shengli, Frazer, Andrew, Bhattacharya, Aniket, University of Central Florida
- Abstract / Description
-
This dissertation is an investigation of the nanoscale characteristics and mechanism of electrolessly deposited silver metal seeded by gold nanoparticles. The process of growing seed-nanoparticles on a polymer surface was studied. Several bifunctional amines and organic reducing agents were used to explore how these chemical factors affect the size and distribution of gold nanoparticles formed at the interface. The nanoparticles were characterized by transmission electron microscopy (TEM) and...
Show moreThis dissertation is an investigation of the nanoscale characteristics and mechanism of electrolessly deposited silver metal seeded by gold nanoparticles. The process of growing seed-nanoparticles on a polymer surface was studied. Several bifunctional amines and organic reducing agents were used to explore how these chemical factors affect the size and distribution of gold nanoparticles formed at the interface. The nanoparticles were characterized by transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). An electroless deposition (ED) bath developed by Danscher was selected to study electroless deposition of silver in detail. The chemical species in the bath were varied to determine how concentration, nature of the carboxylate buffering species, and the presence and absence of gum arabic affect the morphology of silver metal formed by ED and the overall rate of deposition at the surface. The kinetics of deposition using the Danscher bath was studied in detail to elucidate the mechanism of ED. Knowledge generated from this investigation can be used to expand applications of silver ED where strict control over the nanoscale morphology of the deposited metal is required to obtain specific chemical and physical properties.
Show less - Date Issued
- 2018
- Identifier
- CFE0007009, ucf:52051
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007009
- Title
- Novel Fuel-producing Fungi and Methodologies for Increasing Fuel Production.
- Creator
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Wang, Yuemin, Harper, James, Bridge, Candice, Frazer, Andrew, Beazley, Melanie, Blair, Richard, University of Central Florida
- Abstract / Description
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An endophytic fungus Hypoxylon sp. (BS15) has recently been isolated and found to produce volatile organic compounds (VOCs) that have potential relevance as hydrocarbon fuels. In the work described here, the traditional refined carbohydrate (e.g., sucrose) diet source was replaced by simple sugars produced using a solvent free green chemistry mechanocatalytic method involving ball milling in the solid. BS15 is able to grow on this degraded cellulose as well as the more traditional potato...
Show moreAn endophytic fungus Hypoxylon sp. (BS15) has recently been isolated and found to produce volatile organic compounds (VOCs) that have potential relevance as hydrocarbon fuels. In the work described here, the traditional refined carbohydrate (e.g., sucrose) diet source was replaced by simple sugars produced using a solvent free green chemistry mechanocatalytic method involving ball milling in the solid. BS15 is able to grow on this degraded cellulose as well as the more traditional potato dextrose broth. The volatile compounds produced from both media were largely the same. Unfortunately, it is observed that long term in vitro growth of BS15 results in diminished VOC production. The VOC production was partially restored by cultivating BS15 in growth media containing finely ground woody tissue from the original host plant (Taxodium distichum). Extracts from this woody tissue were made by sequentially extracting with dichloromethane, methanol, and water with a goal of isolating VOC production modulators. Both the dichloromethane and water extracts place on bio-mimicking filter paper were found to modulate VOC production, while the methanol extract had no significant impact. Surprisingly, the woody tissue remaining after exhaustive extraction also acted as a VOC production modulator when combined with the growth media, with noticeable changes in the production of four compounds. This woody tissue also induced production of two compounds not observed in the original BS15 extract, and their changes are inheritable. Remarkably filter paper had the same modulating effect as exhaustively extracted woody tissue, suggesting the modulation was partially due to cellulose degradation products. Extraction of the maximum amounts of VOCs is desirable and here a comparison of solid phase extraction (SPE) and solid phase micro-extraction (SPME) techniques is made. This comparison involves two endophytes, BS15C and Streptomyces ambofaciens (SA 40053). The SPE technique is more effective in retaining compounds having lower vapor pressures and higher boiling points with nearly three to five times more VOC mass obtained versus SPME.
Show less - Date Issued
- 2019
- Identifier
- CFE0007552, ucf:52598
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007552
- Title
- Detection of Mercury Through Surface Plasmon Resonance of Immobilized Gold Nanorods.
- Creator
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Trieu, Khang, Campiglia, Andres, Rex, Matthew, Heider, Emily, Frazer, Andrew, Harper, James, Bhattacharya, Aniket, University of Central Florida
- Abstract / Description
-
Mercury is a known environmental pollutant that can damage the brain, heart, kidney and lungs upon exposure. Emissions from fossil fuel plants can release mercury into the air, where it can settle into the water supply and be exposed to human and aquatic life. The use of gold nanorods functionalized on solid substrates as a mercury sensor in tap water samples is investigated herein. The functionalization of the substrates involves the physical immobilization of the nanorods onto the solid...
Show moreMercury is a known environmental pollutant that can damage the brain, heart, kidney and lungs upon exposure. Emissions from fossil fuel plants can release mercury into the air, where it can settle into the water supply and be exposed to human and aquatic life. The use of gold nanorods functionalized on solid substrates as a mercury sensor in tap water samples is investigated herein. The functionalization of the substrates involves the physical immobilization of the nanorods onto the solid surface through the use of (3-mercaptopropyl)trimethoxysilane (MPTMS). The immobilization of the nanorods drastically increases their stability, allowing for use in complicated sample matrices. When gold nanorods are exposed to mercury in aqueous samples, their amalgamation to mercury metal causes a reduction of the effective aspect ratio of the nanoparticles and a blue shift of their maximum longitudinal surface plasmon resonance (SPR) absorption wavelength. Quantitative analysis is made possible due to the linear correlation that exists between the concentration of mercury and the wavelength shift of the maximum SPR absorption wavelength. In order to achieve the quantitative amalgamation of Hg (II) with the nanorods, it is necessary to reduce the mercury ions to mercury metal, which is accomplished herein via chemical or electrochemical processes. Chemical reduction of mercury was been carried out with a strong reducing agent, specifically sodium borohydride. Electrochemical reduction has been accomplished with gold nanorods immobilized on Indium Tin Oxide (ITO) substrates. Mercury determination in tap water using the immobilized gold nanorods was successfully conducted, with further experiments on improving selectivity with potential control, and improving sensitivity through flow injection analysis.
Show less - Date Issued
- 2019
- Identifier
- CFE0007544, ucf:52604
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007544
- Title
- Advancements in Liquid Chromatography for the Determination of Polycyclic Aromatic Compounds in Environmental Samples.
- Creator
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Hayes, Hugh, Campiglia, Andres, Harper, James, Yestrebsky, Cherie, Frazer, Andrew, Coffey, Kevin, University of Central Florida
- Abstract / Description
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The purpose of this dissertation is to provide a new and improved analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in environmental samples. Hundreds of PAHs and PASHs are present in the environment and have great toxicological importance and the chemical determination of these components is a priority. The complete normal-phase liquid chromatography (NPLC) retention behavior has been explored for these...
Show moreThe purpose of this dissertation is to provide a new and improved analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in environmental samples. Hundreds of PAHs and PASHs are present in the environment and have great toxicological importance and the chemical determination of these components is a priority. The complete normal-phase liquid chromatography (NPLC) retention behavior has been explored for these compounds. Retention indices were determined for 124 PAHs, 62 methyl-PAHs (MePAHs), 67 PASHs, and 80 alkyl-PASHs on an aminopropyl (NH2) stationary phase which represents the most comprehensive study of polycyclic aromatic compounds in normal phase conditions to date. NPLC retention behavior for PAHs and PASHs directly correlated to the total number of aromatic carbons in the parent structures. The normal-phase retention behavior information was used to develop an NPLC fractionation procedure to aid in the sample cleanup for complex environmental matrices which can later be analyzed by gas chromatography/mass spectrometry (GC/MS). Standard Reference Material (SRM) 1597a (complex mixture of PAHs in coal tar), SRM 1991 (coal tar/petroleum extract), and SRM 1975 (diesel particulate extract) were analyzed before and after NPLC fractionation by using GC/MS. In SRM 1597a, the NPLC-GC/MS method allowed for the identification of 72 PAHs, 56 Me-PAHs, 35 PASHs, and 59 alkyl-PASHs. The NPLC-GC/MS procedure also provided the tentative identification of 74 PAHs and 117 MePAHs based on the molecular ion peak only. Furthermore, this method allowed for the following identification breakdown: SRM 1991(-)31 PASHs and 58 alkyl-PASHs; and SRM 1975(-)13 PASHs and 25 alkyl-PASHs.Additional work related to the NPLC fractionation of SRM 1597 included the collection of room-temperature fluorescence spectra for the 21 PAHs with molecular mass (MM) 302 Da known to be in SRM 1597a during reversed-phase liquid chromatography (RPLC) separation. Adding spectral features to a chromatographic run provided the tentative identification of 20 PAHs based on retention times and the presence of 18 were confirmed on the basis of spectral profiles. The advancements in liquid chromatography presented in this dissertation via NPLC fractionation along with RPLC stop-flow fluorescence spectra collection shows potential for becoming routine methodologies for PAC determination in complex environmental samples.
Show less - Date Issued
- 2018
- Identifier
- CFE0007190, ucf:52244
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007190
- Title
- Synthesis of Fluorescent Molecules and their Applications as Viscosity Sensors, Metal Ion Indicators, and Near-Infrared Probes.
- Creator
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Wang, Mengyuan, Belfield, Kevin, Campiglia, Andres, Miles, Delbert, Frazer, Andrew, Cheng, Zixi, University of Central Florida
- Abstract / Description
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The primary focus of this dissertation is the development of novel fluorescent near-infrared molecules for various applications. In Chapter 1, a compound dU-BZ synthesized via Sonogashira coupling reaction methodology is described. A deoxyuridine building block was introduced to enhance hydrophilic properties and reduce toxicity, while an alkynylated benzothiazolium dye was incorporated for near-IR emission and reduce photodamage and phototoxicity that is characteristic of common fluorphores...
Show moreThe primary focus of this dissertation is the development of novel fluorescent near-infrared molecules for various applications. In Chapter 1, a compound dU-BZ synthesized via Sonogashira coupling reaction methodology is described. A deoxyuridine building block was introduced to enhance hydrophilic properties and reduce toxicity, while an alkynylated benzothiazolium dye was incorporated for near-IR emission and reduce photodamage and phototoxicity that is characteristic of common fluorphores that are excited by UV or visible light. A 30-fold enhancement of fluorescence intensity of dU-BZ was achieved in a viscous environment. Values of fluorescence quantum yields in 99% glycerol/1% methanol (v/v) of varying temperature from 293 K to 343 K, together with fluorescence quantum yields, radiative and nonradiative rate constants and fluorescence lifetimes in glycerol/methanol solutions of varying viscosities from 4.8 to 950 cP were determined. It was found that both fluorescence quantum yields and fluorescence lifetimes increased with increasing viscosity, which is consistent with results predicted by theory. This suggests that the newly designed compound dU-BZ is capable of functioning as a probe of local microviscosity, and was later confirmed by in vitro bioimaging experiments.In Chapter 2, a new BAPTA (O,O'-bis(2-aminophenyl)ethyleneglycol-N,N,N',N'-tetra acetic acid) and BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based calcium indicator, BAPBO-3, is reported. A new synthetic route was employed to simplify both synthesis and purification, which tend to be low yielding and cumbersome for BAPTA derivatives. Upon excitation, a 1.5-fold increase in fluorescence intensity in buffer containing 39 ?? Ca2+ and a 3-fold increase in fluorescence intensity in buffer containing 1 M Ca2+ was observed; modest but promising fluorescence turn-on enhancements.In Chapter 3, a newly-designed unsymmetrical squaraine dye, SQ3, was synthesized. A one-pot synthesis was employed resulting in a 10% yield, a result that is generally quite favorable for the creation of unsymmetrical squaraines Photophysical and photochemical characterization was conducted in various solvents, and a 678 nm absorption maximum and a 692 nm emission maximum were recorded in DMSO solution with a fluorescence quantum yield of 0.32. In vitro cell studies demonstrated that SQ3 can be used as a near-IR probe for bioimaging.
Show less - Date Issued
- 2014
- Identifier
- CFE0005900, ucf:50863
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005900
- Title
- Photophysics of Organic Probes and their Applications in Bioimaging (&) Photodynamic Therapy.
- Creator
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Kim, Bosung, Belfield, Kevin, Zou, Shengli, Campiglia, Andres, Frazer, Andrew, Ali, Gul Shad, University of Central Florida
- Abstract / Description
-
Over the past several decades the phenomenon of luminescence (divided into fluorescence and phosphorescence) has received great attention in the field of biological science. This quest has motivated scientists for a variety of applications, including fluorescence imaging. Fluorescence microscopy techniques that provide unique advantages, such as high spatial resolution and superior sensitivity, have been regarded as attractive tools in biophotonics. With the progress of ultrafast laser...
Show moreOver the past several decades the phenomenon of luminescence (divided into fluorescence and phosphorescence) has received great attention in the field of biological science. This quest has motivated scientists for a variety of applications, including fluorescence imaging. Fluorescence microscopy techniques that provide unique advantages, such as high spatial resolution and superior sensitivity, have been regarded as attractive tools in biophotonics. With the progress of ultrafast laser sources, two-photon absorption (2PA), in which a molecule absorbs two photons simultaneously, has opened possibilities of using it for various applications. Two-photon fluorescence microscopy (2PFM), which affords deeper tissue penetration and excellent three-dimensional (3D) images, is now being widely employed for bioimaging. This dissertation focuses on the design, synthesis, and photophysical characterization of new fluorophores, as well as desirable applications. Chapter 1 gives an account of a brief introduction of luminescence and 2PA, as well as their utilities in biological applications. In chapter 2, a series of new BODIPY derivatives are presented along with their comprehensive linear and nonlinear characteristics. They exhibited excellent photophysical properties including large extinction coefficients, high fluorescence quantum yields, good photostability, and reasonable two-photon absorption cross sections. Two promising compounds were further evaluated as NIR fluorescent probes in one-photon and two-photon fluorescence imaging. Chapter 3 provides the design, synthesis, and photophysical characterization of two BODIPY dyes. In order to assess the potential of using the dye as a fluorescent probe, Lysotracker Red, a commercial lysosomal marker, was investigated for comparison purposes. The results indicate that figure of merit of both compounds were three orders of magnitude higher than that of Lysotracker Red. With an eye towards applications, one of the compounds was encapsulated in silica-based nanoparticles for in vitro and ex vivo one-photon and two-photon fluorescence imaging, in which the surface of the nanoparticle was modified with RGD peptides for specific targeting. The nanoprobe exhibited good biocompatibility and highly selective RGD-mediated uptake in ?V?3 integrin-overexpressing cancers, while maintaining efficient fluorescence quantum yield and high photostability. In chapter 4, the synthesis and photophysical properties of a novel photosensitizer with heavy atoms (halogen) were presented. The dye exhibited low fluorescence quantum yield, resulting in high singlet oxygen generation quantum yield. In vitro photodynamic studies demonstrated that photosensitization of the agent can induce cellular damage, subsequently leading to cell death by a necrotic cell death mechanism, supporting the therapeutic potential of using the agent for photodynamic therapy.
Show less - Date Issued
- 2015
- Identifier
- CFE0006041, ucf:50977
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006041
- Title
- Fluorescence Off-On Sensors for F-, K+, Fe3+, and Ca2+ Ions.
- Creator
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Sui, Binglin, Belfield, Kevin, Miles, Delbert, Zou, Shengli, Frazer, Andrew, Bhattacharya, Aniket, University of Central Florida
- Abstract / Description
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Fluorescence spectroscopy has been considered to be one of the most important research techniques in modern analytical chemistry, biochemistry, and biophysics. At present, fluorescence is a dominant methodology widely used in a great number of research domains, including biotechnology, medical diagnostics, genetic analysis, DNA sequencing, flow cytometry, and forensic analysis, to name just a few. In the past decade, with the rapid development of fluorescence microscopy, there has been a...
Show moreFluorescence spectroscopy has been considered to be one of the most important research techniques in modern analytical chemistry, biochemistry, and biophysics. At present, fluorescence is a dominant methodology widely used in a great number of research domains, including biotechnology, medical diagnostics, genetic analysis, DNA sequencing, flow cytometry, and forensic analysis, to name just a few. In the past decade, with the rapid development of fluorescence microscopy, there has been a considerable growth in applying fluorescence technique to cellular imaging. The distinguished merits of fluorescence techniques, such as high sensitivity, non-invasiveness, low cytotoxicity, low cost, and convenience, make it a promising tool to replace radioactive tracers for most biochemical measurements, avoiding the high expense and difficulties of handling radioactive tracers.Among the wide range of applications of fluorescence technique, fluorescent sensing of various cations and anions is one of the most important and active areas. This dissertation is all about developing fluorescent sensors for physiologically significant ions, including F-, K+, Fe3+, and Ca2+. All of these sensors demonstrate fluorescence (")turn-on(") response upon interacting with their respective ions, which makes them much more appealing than those based on fluorescence quenching mechanisms.In Chapter II, a novel highly selective fluorescence turn-on F- sensor (FS), comprised of a fluorene platform serving as the chromophore, and two 1,2,3-triazolium groups functioning as the signaling moieties, is described. The function of FS is established on the basis of deprotonation of the C-H bonds of 1,2,3-triazolium groups, which makes FS the first reported anion sensor based on the deprotonation of a C-H bond. Easy-to-prepare test strips were prepared for determining F- in aqueous media, providing an inexpensive and convenient approach to estimate whether the concentration of F- contained in drinking water is at a safe level.Chapter III contains an optimized synthesis of a reported K+-selective group (TAC), and the development of two TAC-based fluorescence turn-on K+ sensors (KS1 and KS2). The synthetic route of TAC is shortened and its overall yield is enhanced from 3.6% to 19.5%. Both KS1 and KS2 exhibited excellent selectivity toward K+ over other physiological metal cations, high sensitivity for K+ sensing, and pH insensitivity in the physiological pH range. Confocal fluorescence microscopy experiments demonstrate that they are capable of sensing K+ within living cells. 2PA determination reveals that KS2 has a desirable 2PA cross section of 500 GM at 940 nm, which makes it a two-photon red-emitting fluorescent sensor for K+.Chapter IV describes the development of a novel BODIPY-based fluorescence turn-on Fe3+ sensor (FeS). FeS is a conjugate of two moieties, a BODIPY platform serving as the fluorophore and a 1,10-diaza-18-crown-6 based cryptand acting as the Fe3+ recognition moiety. FeS displays good selectivity, high sensitivity, reversibility, and pH insensitivity toward Fe3+ sensing. Based on its excellent performance in determining Fe3+ and very low cytotoxicity, FeS was effectively applied to sensing Fe3+ in living cells.In Chapter V, a new BODIPY-based fluorescence turn-on sensor (CaS) was designed and synthesized for selectively and sensitively determining Ca2+. CaS is comprised of two moieties, a BODIPY fluorophore and a Ca2+ complexing unit. CaS demonstrated selective fluorescence turn-on response towards Ca2+ over other biological metal cations. Moreover, CaS exhibited desirable sensitivity for Ca2+ detection, which makes it more suitable for extracellular Ca2+ determination. In addition, CaS was insensitive to the pH of the physiological environment, especially in the pH range of blood and serum. Therefore, CaS has potential to be applied to sensing Ca2+ ions in extracellular environments.Chapter VI discusses potential future work of KS2 and CaS, following the results achieved in this dissertation. Based on the desirable performances of both sensors in sensing their respective ions, future work could largely be focused on their applications in cellular imaging.
Show less - Date Issued
- 2014
- Identifier
- CFE0005888, ucf:50883
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005888
- Title
- In Actu Et In Silicio: Linear and Nonlinear Photophysical Characterization of a Novel Europium Complex, and Incorporating Computational Calculations in the Analysis of Novel Organic Compounds.
- Creator
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Woodward, Adam, Belfield, Kevin, Campiglia, Andres, Harper, James, Frazer, Andrew, Cheng, Zixi, University of Central Florida
- Abstract / Description
-
Despite not being a tangible substance, light is becoming an increasingly valuable tool in numerous areas of science and technology: the use of laser excitation of a fluorescent probe can generate incredibly detailed images of cellular structures without the need for large amounts of dissection; new types of solar cells are being produced using organic dyes to harvest light; computer data can be stored by inducing a chemical change in a compound through irradiation with light. However, before...
Show moreDespite not being a tangible substance, light is becoming an increasingly valuable tool in numerous areas of science and technology: the use of laser excitation of a fluorescent probe can generate incredibly detailed images of cellular structures without the need for large amounts of dissection; new types of solar cells are being produced using organic dyes to harvest light; computer data can be stored by inducing a chemical change in a compound through irradiation with light. However, before any of these materials can be applied in such a way, their properties must first be analyzed for them to be deemed viable.The focus of this dissertation is the photophysical characterization, linear and nonlinear, of a several novel organic compounds, and a europium complex, as well as using quantum chemical calculation techniques to understand some of the phenomena that are witnessed and begin to develop predictive capability. The nonlinear characterization of compounds utilizes wavelengths outside of their linear absorption range, where a focused beam can achieve the same excitation as one at half the wavelength, though this effect has a quadratic dependence on power.The potential for nonlinear excitation, or two-photon absorption (2PA), is becoming of increasing interest and importance for organic chromophores. Exciting only a small volume of material at a focal point makes it possible to nondestructively image samples in 3-dimensions, record data in multiple layers, and fabricate intricate structures through photopolymerization reactions.Lanthanides such as europium are known to exhibit sharp emission bands when excited, typically through an antenna effect due to the low probability of achieving direct excitation. This emission is long-lived, and through gating systems can readily be separated from background noise and autofluorescence (often observed in biological samples) that have much shorter lifetimes. Thus, one of the foci of this dissertation is the photophysical investigation of a series of novel lanthanide complexes, with particular attention to a europium complex.
Show less - Date Issued
- 2014
- Identifier
- CFE0005908, ucf:50891
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005908
- Title
- Investigation of a Novel Magnesium and Acidified Ethanol System for the Degradation of Persistent Organic Pollutants.
- Creator
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Maloney, Phillip, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Frazer, Andrew, Quinn, Jacqueline, University of Central Florida
- Abstract / Description
-
For centuries chemists have sought to improve humankind's quality of life and address many of society's most pressing needs through the development of chemical processes and synthesis of new compounds, often with phenomenal results. Unfortunately, there also are many examples where these chemicals have had unintended, detrimental consequences that are not apparent until years or decades after their initial use. There are numerous halogenated molecules in this category that are globally...
Show moreFor centuries chemists have sought to improve humankind's quality of life and address many of society's most pressing needs through the development of chemical processes and synthesis of new compounds, often with phenomenal results. Unfortunately, there also are many examples where these chemicals have had unintended, detrimental consequences that are not apparent until years or decades after their initial use. There are numerous halogenated molecules in this category that are globally dispersed, resistant to natural degradation processes, bioaccumulative, and toxic to living organisms. Chemicals such as these are classified as persistent organic pollutants (POPs), and due to their negative environmental and health effects, they require safe, effective, and inexpensive means of remediation.This research focuses on the development and optimization of a reaction matrix capable of reductively dehalogenating several POPs. Initial experiments determined that powdered magnesium and 1% V/V acetic acid in absolute ethanol was the most effective system for degrading polychlorinated biphenyl (PCB), an extraordinarily recalcitrant environmental contaminant. Further studies showed that this matrix also was capable of degrading polychlorinated dibenzo-p-dioxins (PCDDs), polybrominated diphenyl ethers (PBDEs), and four organochlorine pesticides (OCPs); dieldrin, heptachlor, heptachlor epoxide, and chlordane. During this phase of testing, field samples contaminated with chlordane were washed with ethanol and this ethanol/chlordane solution was degraded using the same reaction matrix, thereby demonstrating this technology's potential for (")real-world(") remediation projects. Finally, a set of experiments designed to provide some insight into the mechanism of dechlorination seems to indicate that two distinct processes are necessary for degradation to occur. First, the passivated outer layer of the magnesium must be removed in order to expose the zero-valent magnesium core. Next, an electron is transferred from the magnesium to the target molecule, causing the cleavage of the halide bond and the subsequent abstraction of either a hydrogen or proton from a solvent molecule. It is anticipated that an understanding of these fundamental chemical processes will allow this system to be tailored to a wide range of complex environmental media.
Show less - Date Issued
- 2013
- Identifier
- CFE0005109, ucf:50723
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005109
- Title
- Analysis of Benzopyrenes and Benzopyrene Metabolites by Fluorescence Spectroscopy Techniques.
- Creator
-
Al-Farhani, Bassam, Campiglia, Andres, Harper, James, Zou, Shengli, Frazer, Andrew, Lee, Woo Hyoung, University of Central Florida
- Abstract / Description
-
Polycyclic aromatic hydrocarbons (PAHs) are some of the most common and toxic pollutants encountered worldwide. Presently, monitoring is restricted to sixteen PAHs, but it is well understood that this list omits many toxic PAHs. Among the (")forgotten(") PAHs, isomers with molecular weight 302 are of particular concern due to their high toxicological properties. The chromatographic analysis of PAHs with MW 302 is challenged by similar retention times and virtually identical mass fragmentation...
Show morePolycyclic aromatic hydrocarbons (PAHs) are some of the most common and toxic pollutants encountered worldwide. Presently, monitoring is restricted to sixteen PAHs, but it is well understood that this list omits many toxic PAHs. Among the (")forgotten(") PAHs, isomers with molecular weight 302 are of particular concern due to their high toxicological properties. The chromatographic analysis of PAHs with MW 302 is challenged by similar retention times and virtually identical mass fragmentation patterns.The first original component of this dissertation evolves from a high-resolution spectroscopic approach specifically developed to fulfil this gap. Herein, 4.2 K Laser-Excited Time-Resolved Shpol'skii Spectroscopy (4.2K LETRSS) is applied to the analysis of HMW-PAHs in a complex coal tar standard reference material (SRM 1597a). The spectral and lifetime information obtained with LETRSS provide the required selectivity for the unambiguous determination of PAH isomers in the high-performance liquid chromatography (HPLC) fractions. Complete LETRSS analysis is possible with microliters of HPLC fractions and organic solvent. The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach a unique alternative for the analysis of isomers of HMW-PAHs in complex environmental samples.The second original component of this dissertation focuses on the development of screening methodology for the routine analysis of PAH metabolites in urine samples. It explores the room-temperature fluorescence (RTF) properties of 3-hydroxy-benzo[a]pyrene, benzo[a]pyrene-trans-9,10-dihydrodiol, benzo[a]pyrene-r-7,t-8,c-9-tetrahydrotriol and benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol previously extracted with octadecyl-silica membranes. RTF measurements from extraction membranes are carried out with the aid of fiber optic probe that eliminates the need for manual optimization of signal intensities. Relative standard deviations varying from 2.07% (benzo[a]pyrene-r-7,t-8,c-9-tetrahydrotriol) to 8.55% (3-hydroxy-benzo[a]pyrene) were obtained with a straightforward procedure. Analytical recoveries from human urine samples varied from 87.54 (&)#177; 3.11% (3-hydroxy-benzo[a]pyrene) to 99.77 (&)#177; 2.48% (benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol). The excellent analytical figures of merit and the simplicity of the experimental procedure demonstrate the potential of Solid phase extraction-RTF for screening biomarkers of PAH exposure in numerous urine samples.
Show less - Date Issued
- 2016
- Identifier
- CFE0006520, ucf:51363
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006520
- Title
- Detection of Inorganic Phosphate in Environmental Water Samples using a Terbium and Gold Nanoparticle-based FRET Chemosensor.
- Creator
-
Johnson, Madeleine, Campiglia, Andres, Zou, Shengli, Harper, James, Frazer, Andrew, Khondaker, Saiful, University of Central Florida
- Abstract / Description
-
A novel chemosensor for the detection of inorganic phosphate (Pi) in environmental water samples is outlined. The sensing solution is comprised of a luminescent lanthanide, terbium (Tb3+), chelated to ethylenediaminetetraacetic acid (EDTA) acid in solution with cetyltrimethylammonium bromide (CTAB)- capped gold nanoparticles (AuNPs). The Tb-EDTA and AuNPs undergo a Fluorescence resonance energy transfer (FRET) mechanism in which the Tb3+ luminescence is quenched. Upon the addition of...
Show moreA novel chemosensor for the detection of inorganic phosphate (Pi) in environmental water samples is outlined. The sensing solution is comprised of a luminescent lanthanide, terbium (Tb3+), chelated to ethylenediaminetetraacetic acid (EDTA) acid in solution with cetyltrimethylammonium bromide (CTAB)- capped gold nanoparticles (AuNPs). The Tb-EDTA and AuNPs undergo a Fluorescence resonance energy transfer (FRET) mechanism in which the Tb3+ luminescence is quenched. Upon the addition of inorganic phosphate (Pi), the AuNPs begin to aggregate and precipitate out of solution. The aggregation of AuNPs results in the restoration of the Tb-EDTA signal which can then be correlated to Pi concentration in the matrix of analysis. The developed sensor has the potential for on-site monitoring of Pi in environmental waters at the sampling location; this would be advantageous for the prevention and understanding of eutrophication events caused by anthropogenic release of nutrients such as Pi. The limit of detection (LOD) of the luminescence sensor (83 ppb-Pi) is within the range of LODs previously reported for on-site monitoring of Pi. Quantitative analysis carried out via the multiple standard additions method provided accurate determination of Pi concentrations in heavily contaminated environmental waters. Additional studies include the synthesis of an organic antenna for the sensitization of the lanthanide ion and further improvement of detection levels.
Show less - Date Issued
- 2017
- Identifier
- CFE0006747, ucf:51874
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006747
- Title
- Application of Two-Photon Absorbing Fluorene-Containing Compounds in Bioimaging and Photodyanimc Therapy.
- Creator
-
Yue, Xiling, Belfield, Kevin, Campiglia, Andres, Miles, Delbert, Frazer, Andrew, Cheng, Zixi, University of Central Florida
- Abstract / Description
-
Two-photon absorbing (2PA) materials has been widely studied for their highly localized excitation and nonlinear excitation efficiency. Application of 2PA materials includes fluorescence imaging, microfabrication, 3D data storage, photodynamic therapy, etc. Many materials have good 2PA photophysical properties, among which, the fluorenyl structure and its derivatives have attracted attention with their high 2PA cross-section and high fluorescence quantum yield.Herein, several compounds with...
Show moreTwo-photon absorbing (2PA) materials has been widely studied for their highly localized excitation and nonlinear excitation efficiency. Application of 2PA materials includes fluorescence imaging, microfabrication, 3D data storage, photodynamic therapy, etc. Many materials have good 2PA photophysical properties, among which, the fluorenyl structure and its derivatives have attracted attention with their high 2PA cross-section and high fluorescence quantum yield.Herein, several compounds with 2PA properties are discussed. All of these compounds contain one or two fluorenyl core units as part of the conjugated system. The aim of this dissertation is to discuss the application of these compounds according to their photophysical properties. In chapters 2 to 4, compounds were investigated for cell imaging and tissue imaging. In chapter 5, compounds were evaluated for photodynamic therapy effects on cancer cells. Chapters 2 and 3 detail compounds with quinolizinium and pyran as core structures, respectively. Fluorene was introduced into structures as substituents. Quinolizinium structures exhibited a large increase in fluorescence when binding with Bovine Serum Albumin (BSA). Further experiments in cell imaging demonstrated a fluorescence turn-on effect in cell membranes, indicating the possibility for these novel compounds to be promising membrane probes. Pyran structures were conjugated with arginylglycylaspartic acid peptide (RGD) to recognize integrin and introduced in cells and an animal model with tumors. Both probes showed specific targeting of tumor vasculature. Imaging reached penetration as deep as 350 ?m in solid tumors and exhibited good resolution. These results suggest the RGD-conjugated pyran structure should be a good candidate probe for live tissue imaging. Chapter 4 applied a fluorene core structure conjugated with RGD as well. Application of this fluorenyl probe compound is in wound healing animal models. Fluorescence was collected from vasculature and fibroblasts up to ? 1600 ?m within wound tissue in lesions made on the skin of mice. The resolution of images is also high enough to recognize cell types by immunohistochemical staining. This technology can be applied for reliable quantification and illustration of key biological processes taking place during tissue regeneration in the skin. Chapter 5 describes three fluorenyl core structures with photoacid generation properties. One of the structures showed excellent photo-induced toxicity. Cancer cells underwent necrotic cell death due to pH decrease in lysosomes and endosomes, suggesting a new mechanism for photodynamic therapy.
Show less - Date Issued
- 2014
- Identifier
- CFE0005565, ucf:50276
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005565
- Title
- Enhanced Two-Photon Absorption in a Squaraine-Fluorene-Squaraine Dye: Design, Synthesis, Photophysical Properties, and Solvatochromic Behavior.
- Creator
-
Moreshead, William, Belfield, Kevin, Campiglia, Andres, Zou, Shengli, Frazer, Andrew, Beiler, Rosalind, University of Central Florida
- Abstract / Description
-
The discovery of any new technology is usually accompanied by a need for new or improved materials which make that technology useful in practical applications. In the case of two-photon absorption (2PA) this has truly been the case. Since its first demonstration in 1961, there has been an ever increasing quest to understand the relationships between two-photon absorption and the structure of two-photon absorbing materials. This quest has been motivated by the many applications for 2PA which...
Show moreThe discovery of any new technology is usually accompanied by a need for new or improved materials which make that technology useful in practical applications. In the case of two-photon absorption (2PA) this has truly been the case. Since its first demonstration in 1961, there has been an ever increasing quest to understand the relationships between two-photon absorption and the structure of two-photon absorbing materials. This quest has been motivated by the many applications for 2PA which have been reported, including fluorescence bioimaging, 3D microfabrication, 3D optical data storage, upconverted lasing, and photodynamic therapy.The work presented in this dissertation represents another step in the effort to better understand the structure/property relationships of 2PA. In this work a new, squaraine-fluorene-squaraine molecule, proposed through a joint effort of quantum and synthetic chemists, was synthesized and its photophysical properties were measured. The measurements included linear and two-photon photophysical properties, as well as solvatochromic behavior. Quantum calculations were done to aid in understanding those photophysical and solvatochromic properties. A single squaraine dye was also synthesized and used as a model compound to assist in understanding this new structure.In Chapter 1 an introduction to 2PA and several of its applications is given. Chapter 2 gives a background of 2PA structure/property relationships that have been reported to date, based on work done with polymethine dyes. Chapter 3 gives a full account of the synthesis, characterization, and detailed quantum chemical analyses of this new squaraine-fluorene-squaraine molecule and the corresponding model compound squaraine dye. Chapter 4 gives some additional work and suggested future directions.
Show less - Date Issued
- 2013
- Identifier
- CFE0005384, ucf:50450
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005384
- Title
- Squaraine dyes, design and synthesis for various functional materials applications.
- Creator
-
Zhang, Yuanwei, Belfield, Kevin, Campiglia, Andres, Zou, Shengli, Frazer, Andrew, Cheng, Zixi, University of Central Florida
- Abstract / Description
-
This dissertation contains the synthesis and characterization of squaraine based new functional materials. In the first part of this thesis work, a water soluble benzothiazolium squaraine dye was synthesized with pyridium pendents, and controlled aggregation properties were achieved. After formation of partially reversible J-aggregation on a polyelectrolyte (poly(acryl acid) sodium salt) template, the nonlinear, two-photon absorption cross section per repeat unit was found to be above 30-fold...
Show moreThis dissertation contains the synthesis and characterization of squaraine based new functional materials. In the first part of this thesis work, a water soluble benzothiazolium squaraine dye was synthesized with pyridium pendents, and controlled aggregation properties were achieved. After formation of partially reversible J-aggregation on a polyelectrolyte (poly(acryl acid) sodium salt) template, the nonlinear, two-photon absorption cross section per repeat unit was found to be above 30-fold enhanced compared with nonaggregate and/or low aggregates. Using a similar strategy, sulfonate anions were introduced into the squaraine structure, and the resulting compounds exhibited good water solubilities. A 'turn on' fluorescence was discovered when these squaraine dyes interacted with bovine serum albumin (BSA), titration studies by BSA site selective reagents show these squaraine dyes can bind to both site I and II of BSA, with a preference of site II. Introduction of these squaraine dyes to BSA nanoparticles generated near-IR protein nano fabricates, and cell images were collected. Metal sensing properties were also studied using the sulfonates containing a benzoindolium squaraine dye, and the linear response of the absorption of the squaraine dye to the concentration of Hg2+ makes it a good heavy metal-selective sensing material that can be carried out in aqueous solution. Later, a squaraine scaffold was attached to deoxyribonucleosides by Sonogashira coupling reactions, in which the reaction conditions were modified. Iodo-deoxyuridine and bromo-deoxyadenosine were used as the deoxyribonucleosides building blocks, and the resulting squaraine dye-modified deoxyribonucleosides exhibited near-IR absorption and emission properties due to the squaraine chromophore. Interestingly, these non-natural deoxyribonucleosdies showed viscosity dependent photophysical properties, which make them nice candidates for fluorescence viscosity sensors at the cellular level. After incubation with cells, these viscosity sensors were readily uptaken by cell, and images were obtained showing regions of high viscosity in cells.
Show less - Date Issued
- 2013
- Identifier
- CFE0005451, ucf:50369
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005451
- Title
- Photo-induced Protonation of Polyaniline Composites and Mechanistic Study of the Degradation of Polychlorinated Biphenyls with Zero-Valent Magnesium.
- Creator
-
Kirkland, Candace, Yestrebsky, Cherie, Campiglia, Andres, Clausen, Christian, Frazer, Andrew, Duranceau, Steven, University of Central Florida
- Abstract / Description
-
As technology advances, a need for non-metal, conductive materials has arisen for several types of applications. Lithographic techniques are helpful to develop some of these applications. Such techniques require materials that are insulating and become conductive after irradiated. Composites of polyaniline in its emeraldine base form (PANI-EB) doped with photo-acid generators (PAG) become conductive upon photo-irradiation. This increase in conductivity is due to the protonation of PANI-EB....
Show moreAs technology advances, a need for non-metal, conductive materials has arisen for several types of applications. Lithographic techniques are helpful to develop some of these applications. Such techniques require materials that are insulating and become conductive after irradiated. Composites of polyaniline in its emeraldine base form (PANI-EB) doped with photo-acid generators (PAG) become conductive upon photo-irradiation. This increase in conductivity is due to the protonation of PANI-EB. Such materials may be utilized to fabricate conducting patterns by photo-irradiation; however, the conductivity obtained by direct irradiation of PANI-EB/PAG composites is normally quite low ((<)10-3 S/cm) due to aggregation of highly loaded PAG. In this work, poly(ethylene glycol) (PEG), a proton transfer polymer, was added to PANI-EB/PAG. Results showed the addition of low molecular weight (MW) (550) PEG significantly enhanced the photo-induced conductivity to a level comparable to that of PANI-salt synthesized by oxidizing aniline in the presence of an acid. High MW (8000) PEG is less effective than PEG 550, and composites of PANI-EB and N-PEG-PANI showed conductivity as high as 102 S/cm after treatment with HCl vapor. The photo-induced conductivity of the N-PEG-PANI/PANI-EB/PAG composite reached 10-2-10-1 S/cm. Polychlorinated biphenyls (PCBs) are a class of chemicals with 209 different congeners, some of which are known carcinogens, and are persistent organic pollutants in the environment. After its synthesis, it was seen as a phenomenal additive in a multitude of different applications leading to the wide spread use of PCBs and a need for a safe, effective, and inexpensive remediation technique. While it is known that magnesium can degrade PCBs, the mechanism of this reaction was not well-understood. In order for magnesium to be broadly used as a remediation tool, it is necessary to fully understand how the reaction is taking place and if the PCBs are able to be fully dechlorinated into biphenyl. This research focuses on the hydrodechlorination of PCBs with zero-valent magnesium in acidified ethanol. The degradation pathways of 2, 2', 3, 5, 5', 6- hexachlorobiphenyl were investigated to determine the identity of the daughter PCBs produced, how and if they continue to be dechlorinated into biphenyl. The proton source for this hydrodehalogenation reaction was also studied using both deuterated solvent and acid to give more detail to the mechanism of this reaction.
Show less - Date Issued
- 2014
- Identifier
- CFE0005513, ucf:50308
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005513
- Title
- Magnesium and Acidified Ethanol Based Treatment Systems for the Extraction and Dechlorination of Polychlorinated Biphenyls from Contaminated Oils, Paints, and Soils.
- Creator
-
Novaes-Card, Simone, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Frazer, Andrew, Duranceau, Steven, University of Central Florida
- Abstract / Description
-
Polychlorinated biphenyls (PCBs) are a class of environmentally persistent halogenated organic compounds that were once used as stabilizers to improve the properties of a variety of materials such as lubricants, heat transfer fluids, paints, and caulking materials. PCBs are also capable of migration through processes such as spillage into soils, leaching into groundwater, and volatilization into the atmosphere. Although banned in 1979 over health concerns, PCBs persist in these materials to...
Show morePolychlorinated biphenyls (PCBs) are a class of environmentally persistent halogenated organic compounds that were once used as stabilizers to improve the properties of a variety of materials such as lubricants, heat transfer fluids, paints, and caulking materials. PCBs are also capable of migration through processes such as spillage into soils, leaching into groundwater, and volatilization into the atmosphere. Although banned in 1979 over health concerns, PCBs persist in these materials to this day because they are resistant to biotic degradation and natural weathering processes. The wide variety of contaminated materials means that many existing treatment options cannot be used across all media. This research focuses on the adaptation of a reductive dehalogenation system for dechlorination of PCBs from machine oils, paints, sludges, and soils. The system utilizes magnesium, glacial acetic acid, and ethanol in order to remove the chlorine atoms from the biphenyl backbone, which is less toxic and can be broken down biotically.A treatment plan was devised for machine oil contaminated with PCBs, involving sorption of PCBs onto a column of super activated alumina followed by desorption into hexane and treatment of the hexane with magnesium and acidified ethanol to dechlorinate the PCBs. In a small-scale study, 98.5% of PCBs from an oil sample were sorbed to the column, and the PCBs that were subsequently desorbed were dechlorinated to below detectable levels within one day of magnesium and acidified ethanol treatment. Information from small-scale studies was used to design larger sorption columns intended for use at a field site.A field study was conducted to compare the effectiveness of two different treatment system pastes at removing PCBs from painted surfaces. These pastes were formulated with bulking and viscosity control agents in order to cling to vertical surfaces, and contained either acidified ethanol and magnesium (Activated Metal Treatment System, AMTS) or acidified ethanol only (Non-Metal Treatment System, NMTS). AMTS was capable of 64.8% average removal of PCBs from paint, while NMTS demonstrated 89.5% average removal but required a second step to dechlorinate the extracted PCBs. This system allows for treatment of surfaces without demolishing the structure. AMTS was also studied for in situ dechlorination of PCBs in soils, and NMTS enclosed in a polyethylene barrier was studied for extraction of PCBs from sludges.A two-step system was devised for the ex situ treatment of PCB-contaminated soils. Solvent extraction with ethanol or an ethanol/ethyl lactate cosolvent is followed by dechlorination using magnesium and glacial acetic acid. Studies included the optimization of extraction solvent, cosolvent ratio, cost, and reuse of magnesium or extraction solvent. Surface analysis of magnesium particles used in dechlorination showed a precipitate occluding part of the surface, which was thought to be a combination of magnesium ethoxide and magnesium hydroxide. This precipitate is thought to come from the reaction of magnesium ethoxide formed during the PCB dechlorination process with pore water extracted from the soil.
Show less - Date Issued
- 2013
- Identifier
- CFE0005222, ucf:50630
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005222
- Title
- Chemistry and(&)nbsp;Structure of Ru/SiO2(&)nbsp;and Ru/Al2O3 Interfaces.
- Creator
-
Ezzat, Sameer, Campiglia, Andres, Coffey, Kevin, Zou, Shengli, Frazer, Andrew, Harper, James, Coffey, Kevin, University of Central Florida
- Abstract / Description
-
The resistivity size effect in nanoscale metals is of both scientific and technological interest, the latter due to its importance to interconnects between transistors in integrated circuits. In this work we report the variation of resistivity associated with surface scattering of ex-situ annealed single crystal Ru thin films grown on sapphire substrates by sputter deposition. A set of samples were overcoated with dielectric and subjected to a variety of reducing and oxidizing anneals. The...
Show moreThe resistivity size effect in nanoscale metals is of both scientific and technological interest, the latter due to its importance to interconnects between transistors in integrated circuits. In this work we report the variation of resistivity associated with surface scattering of ex-situ annealed single crystal Ru thin films grown on sapphire substrates by sputter deposition. A set of samples were overcoated with dielectric and subjected to a variety of reducing and oxidizing anneals. The changes in the chemistry and structure of the dielectric interface induced by the anneals, as determined by x-ray reflectivity and x-ray photoelectron spectroscopy measurements, are related to the changes in the specularity of the surface for electron scattering in the context of the Fuchs-Sondheimer semi-classical model of the resistivity size effect.
Show less - Date Issued
- 2019
- Identifier
- CFE0007454, ucf:52727
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007454