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Title: ROOM TEMPERATURE FLUORESCENCE SPECTROSCOPY AS A TOOL FOR THE FORENSIC TRACE ANALYSIS OF TEXTILE FIBERS.
Creator: Rex, Matthew, Campiglia, Andres, University of Central Florida
Abstract / Description: ABSTRACT Trace textile fiber evidence is found at numerous crime scenes and plays an important role in linking a suspect to the respective scene. Several methods currently exist for the analysis of trace fiber evidence. Microscopy provides information regarding the fibers material, color and weave. For more detailed chemical analysis chromatographic methods are employed and for discrimination between dyes, liquid chromatography coupled with mass spectrometry (LC-MS) is currently the method...
Show moreABSTRACT Trace textile fiber evidence is found at numerous crime scenes and plays an important role in linking a suspect to the respective scene. Several methods currently exist for the analysis of trace fiber evidence. Microscopy provides information regarding the fibers material, color and weave. For more detailed chemical analysis chromatographic methods are employed and for discrimination between dyes, liquid chromatography coupled with mass spectrometry (LC-MS) is currently the method providing the most discrimination. These methods have primarily focused on the dyes used to color the fibers and have not investigated other components that can potentially discriminate among fibers. This dissertation deals with investigations into the fluorescence of the fiber dyes, (contaminants?) and the fibers themselves, as well as methodology for discriminating between fibers using fluorescence. Initial systematic analysis was conducted on dye standards and extracts taken from fibers colored with the respective dyes of interest. Absorbance, excitation and fluorescence spectra were compared between standards and extracts to determine the optimal area of the fiber to investigate: dyes, fluorescent impurities or the whole fiber. High performance liquid chromatography investigations were performed to give detailed information on the number of dye and fluorescent components present in extracts. Our investigations then focused on the best room-temperature fluorescence (RTF) data format for analysis and discrimination of fiber samples. An excitation emission matrix (EEM) was found to give the greatest amount of spectral information and provide the highest level of discrimination. Successful discrimination between non similar and similar fibers was achieved with the aid of Chemometric analysis. The level of discrimination obtained via RTF-EEM spectroscopy was sufficient to differentiate among fibers obtained from two separate cloths of the same material and colored with the same dye reagent. Final studies deal with examining exposure of the fiber to various environmental contaminants. Clothing fibers are typically exposed to myriad numbers of contaminants, from food stains to cigarette smoke. The challenge then becomes detecting fluorescence signals from trace amounts of these environmental contaminants. We demonstrate the detection and classification of polycyclic aromatic hyrdrocarbons (PAH) present on fibers after exposure to cigarette smoke. This dissertation also investigates the change in fluorescence emission after laundering fibers numerous times. The main drawback of chemical analysis of fibers is the destructive nature of the methods. To extract a dye or contaminant from a fiber essentially destroys the evidence. This leaves the investigator without their original sample in the courtroom. This also provides a finite amount of sample for testing and analysis. This is true of chromatographic methods and for the method detailed in this dissertation which makes use of extracts taken from fiber samples. Lastly, we propose an instrumental setup coupling a microscope to a spectrofluorimeter for the purpose of taking EEM directly from a fiber sample. This setup makes use of the superior optics of the microscope for focusing excitation light onto the fiber sample. Initial studies have been performed on extracts from a single textile fiber and EEM collected from said fiber.
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Date Issued: 2009
Identifier: CFE0002833, ucf:48084
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002833

Title: Qualitative and Quantitative Elemental Composition Analysis of the Surrounding Pollen Coating via ICP-MS.
Creator: Voyer, Brandy, Baudelet, Matthieu, Rex, Matthew, Sigman, Michael, University of Central Florida
Abstract / Description: Pollen evidence has proven to be a powerful forensic tool to trace a suspect or item to a victim or a crime scene. This is possible because it is microscopic, abundant in nature, resistant to degradation and decay; it presents dispersal patterns that can be used to generate a 'fingerprint' within specific areas, and has illustrated a unique morphology that can be used to classify species. While the pollen grain morphology has been extensively used to characterize the specific species, not...
Show morePollen evidence has proven to be a powerful forensic tool to trace a suspect or item to a victim or a crime scene. This is possible because it is microscopic, abundant in nature, resistant to degradation and decay; it presents dispersal patterns that can be used to generate a 'fingerprint' within specific areas, and has illustrated a unique morphology that can be used to classify species. While the pollen grain morphology has been extensively used to characterize the specific species, not much has been investigated as pertains to the coating that surrounds the pollen grain aside from it being categorized as waste. This Master thesis focuses on the qualitative and quantitative determination of the elemental composition of this coating surrounding pollen via Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Two methodologies for sample preparation were compared: a complete digestion and analysis of (i) the entire pollen and (ii) the surrounding pollen coating alone removed from the pollen grain by Soxhlet extraction in ethanol. The goal was to discern the elemental composition of the coating and its specific elemental composition in comparison with the whole pollen grain. The results of both F-test and T-test performed for three pollen species indicated that, of the 19 elements investigated, B, Mg, Mn, K, Ti, and Cs resulted in significant differences between the whole grain and the coating alone; while Se, V, Pb, Cr, Al, and Zn can be recognized as being characteristic of the coating surrounding the pollen grain.
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Date Issued: 2018
Identifier: CFE0007261, ucf:52189
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007261

Title: A Complete Approach to Predict Biodistribution of Nanomaterials Within Animal Species from In-vitro Data.
Creator: Price, Edward, Gesquiere, Andre, Huo, Qun, Kolpashchikov, Dmitry, Rex, Matthew, Ebert, Steven, University of Central Florida
Abstract / Description: Smart drug-design for antibody and nanomaterial-based therapies allows for optimization of drug efficacy and more efficient early-stage pre-clinical trials. The ideal drug must display maximum efficacy at target tissue sites, but to track and predict distribution to these sites, one must have a mechanistic understanding of the kinetics involved with the individual cells of the tissue itself. This process can be tracked through biological simulations coupled with in-vitro approaches, which...
Show moreSmart drug-design for antibody and nanomaterial-based therapies allows for optimization of drug efficacy and more efficient early-stage pre-clinical trials. The ideal drug must display maximum efficacy at target tissue sites, but to track and predict distribution to these sites, one must have a mechanistic understanding of the kinetics involved with the individual cells of the tissue itself. This process can be tracked through biological simulations coupled with in-vitro approaches, which result in a rapid and efficient in-depth understanding of drug transport within tissue vasculature and cellular environment. As a result, it becomes possible to predict drug biodistribution within live animal tissue cells without the need for animal studies. Herein, we use in-vitro assays to translate transport kinetics to whole-body animal simulations to predict drug distribution from vasculature into individual tissue cells for the first time. Our approach is based on rate constants obtained from an in-vitro assay that accounts for cell-induced degradation, which are translated to a complete animal simulation to predict nanomedicine biodistribution at the single cell level. This approach delivers predictions for therapies of varying size and type for multiple species of animals solely from in-vitro data. Thus, we expect this work to assist in refining, reducing, and replacing animal testing, while at the same time, giving scientists a new perspective during early stages of drug development.
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Date Issued: 2019
Identifier: CFE0007900, ucf:52747
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007900

Title: Remediation of chlorinated alkanes by zero valent iron with vitamin B12 and Utilization of a modified Gradual Release of Responsibility model in a large enrollment chemistry course.
Creator: Lapeyrouse, Nicole, Yestrebsky, Cherie, Beazley, Melanie, Chen, Gang, Rex, Matthew, Randall, Andrew, University of Central Florida
Abstract / Description: The following dissertation looks at addressing environmental contaminants in the environment and the integration of an active learning style in an introductory chemistry course. It begins with addressing the concern for chlorinated propanes and ethane in the environment and the importance of looking into environmental remediation applications. This research looks at incorporating vitamin B12 as an environmentally friendly catalyst in the presence of zero valent iron for the reduction of...
Show moreThe following dissertation looks at addressing environmental contaminants in the environment and the integration of an active learning style in an introductory chemistry course. It begins with addressing the concern for chlorinated propanes and ethane in the environment and the importance of looking into environmental remediation applications. This research looks at incorporating vitamin B12 as an environmentally friendly catalyst in the presence of zero valent iron for the reduction of chlorinated propanes and ethane. Chapter 2 presents the analytical methods and conditions in which samples were run. The results from these experiments are discussed in length in Chapter 3. Our results confirmed the hypothesis that vitamin B12 could act as an electron mediator to facilitate the reduction of the chlorinated propanes and ethane. Degradation was examined by observing the formation of byproduct peaks and the release of free chloride into solution. In Chapter 4, vitamin B12 is integrated into an already established industrial application technique, emulsified zero valent iron, and we observed the degradation of 1,2,3-trichloropropane with the formation of byproducts as the reaction progressed. In Chapter 5, this section of the dissertation focused on chemical education and observing an active learning technique in a fundamental chemistry course. The following study was designed to increase students' positive attitude, engagement, and responsibility in a large enrollment chemistry course by utilizing a modified Gradual Release of Responsibility (GRR) model. GRR progressively transfers responsibility from the instructor to the student, allowing students to be more independent and helping them to address atypical problems. Students were assessed using iClickers to monitor their understanding and engagement, as well as surveys to determine their attitudes regarding this specific style of teaching. The results from this study demonstrated that implementing the GRR teaching style had a positive effect on student academic performance and shows the importance of using an active teaching model in a large enrollment course.
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Date Issued: 2018
Identifier: CFE0007759, ucf:52373
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007759

Title: Detection of Mercury Through Surface Plasmon Resonance of Immobilized Gold Nanorods.
Creator: 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.
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Date Issued: 2019
Identifier: CFE0007544, ucf:52604
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007544

Title: Nitrogen-Containing Materials for Mechanochemical Synthesis, Luminescence Analysis, and Heterogeneous Catalysis.
Creator: Nash, David, Zhai, Lei, Hampton, Michael, Harper, James, Rex, Matthew, Blair, Richard, University of Central Florida
Abstract / Description: Various inorganic nitrogen-containing materials have been exploited for their different properties. Several nitride materials are commercially attractive due to their mechanical properties making them suitable for ceramic industries and wide bandgaps fitting for use as semiconductor and insulator materials, as well as optoelectronics. Nitride materials can exhibit versatility in applications such as the use of gallium nitride to make blue LEDs, nitrides of titanium and silicon being utilized...
Show moreVarious inorganic nitrogen-containing materials have been exploited for their different properties. Several nitride materials are commercially attractive due to their mechanical properties making them suitable for ceramic industries and wide bandgaps fitting for use as semiconductor and insulator materials, as well as optoelectronics. Nitride materials can exhibit versatility in applications such as the use of gallium nitride to make blue LEDs, nitrides of titanium and silicon being utilized as medical implants for their chemical inertness and hardness, and the heavy use of boron nitride as a solid lubricant in the cosmetic industry. Amines have been used as nitrogen-containing organic ligands in organometallic complexes that exhibit phenomenal photophysical properties. These complexes have been heavily studied for potential applications in optoelectronics and chemical sensing. This dissertation will focus on two nitrogen-containing materials that have yet to be explored for the potential applications to be discussed. The first is hexagonal-boron nitride (h-BN), which was previously mentioned to have a substantial use in the cosmetic industry, giving products such as lipstick, foundation, and blush their slick feeling. Computational models have shown the possibility of altered electronic properties of defect sites in the h-BN sheets. These defect sites will be explored experimentally to determine any catalytic activity. Specifically, the hydrogenation reaction using defect-laden hexagonal-boron nitride will be investigated. Successful catalysis would add to the short list of non-metal catalyst, and provide an alternative catalyst that costs significantly less than the traditional metal catalysts commonly used in commercial industries. The second of the two nitrogen-containing materials is a class of metal complexes based on organometallic clusters of copper(I) iodide. Copper(I) iodide clusters formed with amine ligands have been studied for around four decades and the photophysics behind their photoluminescent properties are well understood. Much of the work has been done for use as a potential emissive material in the optoelectronics field. They have also been studied for applications in the sensing of environmental compounds. Here, research will display its use as a novel sensor for narcotic substances. This forensic application will be further explored to develop and eventually commercialize a complete field drug testing system for law enforcement and crime lab use, with the goal to equip law enforcement personnel with a presumptive drug testing method that is accurate, easy-to-use, safe, adaptable, and affordable. This system will consist of a narcotic drug-indicating test strip, a handheld fluorescence spectrometer manufactured in-house using relatively inexpensive parts, and a mobile app that will leverage photoemission data of the tested drug samples collected by multiple crime labs to provide the ability for sample-to-reference data matching. Law enforcement users would have the ability to rapidly identify an unknown substance by applying it to a test strip, testing it using the spectrometer, and capturing an image of the resulting photoemission and analyzing the spectral profile in search of a match with the support of a cloud database.
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Date Issued: 2017
Identifier: CFE0007129, ucf:52297
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007129

Title: Improvements on Instrumentation to Explore the Multidimensionality of Luminescence Spectroscopy.
Creator: Moore, Anthony, Campiglia, Andres, Chumbimuni Torres, Karin, Harper, James, Rex, Matthew, Lee, Woo Hyoung, University of Central Florida
Abstract / Description: This dissertation presents experimental and instrumentation developments that take full advantage of the multidimensional nature of line narrowing spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2 K) temperatures. The inconvenience of sample freezing procedures is eliminated with the aid of cryogenic fiber optic probes. Rapid collection of multidimensional data formats such as wavelength time matrices, excitation emission matrices, time-resolved excitation emission matrices and...
Show moreThis dissertation presents experimental and instrumentation developments that take full advantage of the multidimensional nature of line narrowing spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2 K) temperatures. The inconvenience of sample freezing procedures is eliminated with the aid of cryogenic fiber optic probes. Rapid collection of multidimensional data formats such as wavelength time matrices, excitation emission matrices, time-resolved excitation emission matrices and time resolved excitation emission cubes is made possible with the combination of a pulsed tunable dye laser, a spectrograph and an intensifier-charged coupled device. These data formats provide unique opportunities for processing vibrational luminescence data with second order multivariate calibration algorithms. The use of cryogenic fiber optic probes is extended to commercial instrumentation. An attractive feature of spectrofluorimeters with excitation and emission monochromators is the possibility to record synchronous spectra. The advantages of this approach, which include narrowing of spectral bandwidth and simplification of emission spectra, were demonstrated with the direct analysis of highly toxic dibenzopyrene isomers. The same is true for the collection of steady-state fluorescence excitation-emission matrices. These approaches provide a general solution to unpredictable spectral interference, a ubiquitous problem for the analysis of organic pollutants in environmental samples of unknown composition. Since commercial spectrofluorimeters are readily available in most academic institutions, industrial settings and research institutes, the developments presented here should facilitate the widespread application of line-narrowing spectroscopic techniques to the direct determination, no chromatographic separation, of highly toxic compounds in complex environmental matrixes of unknown composition.
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Date Issued: 2015
Identifier: CFE0005847, ucf:50934
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005847

Title: Multidimensional Room-Temperature Fluorescence Microscopy for the Nondestructive Analysis of Forensic Trace Textile Fibers.
Creator: Mujumdar, Nirvani, Campiglia, Andres, Sigman, Michael, Harper, James, Rex, Matthew, Peale, Robert, University of Central Florida
Abstract / Description: The purpose of this dissertation is to advance nondestructive methodology for forensic fiber examination. Non-destructive techniques that can either discriminate between similar fibers or match a known to a questioned fiber (-) and still preserve the physical integrity of the fibers for further court examination - are highly valuable in forensic science. A challenging aspect of forensic fiber examinations involves the comparison of fibers colored with visually indistinguishable dyestuffs....
Show moreThe purpose of this dissertation is to advance nondestructive methodology for forensic fiber examination. Non-destructive techniques that can either discriminate between similar fibers or match a known to a questioned fiber (-) and still preserve the physical integrity of the fibers for further court examination - are highly valuable in forensic science. A challenging aspect of forensic fiber examinations involves the comparison of fibers colored with visually indistinguishable dyestuffs. This is not an uncommon situation, as there are numerous indistinguishable fibers pre-dyed with commercial dyes of virtually identical colors. Minimal chemical structural variations are actually encouraged by the dye patent process and commercial competition.The common denominator to forensic methodology is the fact that fiber analysis primarily focuses on the dyes used to color the fibers and do not investigate other potential discriminating components present in the fiber. This dissertation explores a different aspect of fiber analysis as it focuses on the total fluorescence emission of fibers. In addition to the contribution of the textile dye (or dyes) to the fluorescence spectrum of the fiber, we consider the contribution of intrinsic fluorescence impurities (-) i.e. impurities imbedded into the fibers during fabrication of garments - as a reproducible source of fiber comparison. Although fluorescence microscopy is used in forensic labs for single fiber examination, measurements are made with the aid of band-pass filters that provide very limited information on the spectral profiles of fibers. We take the non-destructive nature of fluorescence microscopy to a higher level of selectivity with the collection of room-temperature fluorescence excitation emission matrices (RTF-EEMs). The information contained in the EEMs was first used to select the best excitation wavelength for recording first order data, i.e. two-dimensional fluorescence spectra. Pairwise comparisons involved the following visually indistinguishable fibers: nylon 361 pre-dyed with acid yellow (AY) 17 and AY 23, acrylic 864 pre-dyed with basic green (BG) 1 and BG 4, acetate satin 105B pre-dyed with disperse blue (DB) 3 and DB 14, and polyester 777 pre-dyed with disperse red (DR) 1 and DR 19. With the exception of acrylic 864 fibers dyed with BG1 and BG4, the comparison of two-dimensional spectra via principal component analysis (PCA) provided accurate fiber identification for all the analyzed fibers. The same approach was later applied to the investigation of laundering effects on the comparison of textile fibers. The presence of brighteners and other detergent components adsorbed in the fibers provided spectral fingerprints that enhanced the fiber identification process.The full dimensionality of EEMs was then explored with the aid of parallel factor analysis (PARAFAC), a second order algorithm capable to determine the number of fluorescence components that contribute to an EEM along with their individual excitation and emission profiles. The application of PARAFAC was carried out unsupervised and supervised by linear discrimination analysis (LDA). The classification performances of PARAFAC and LDA-supervised PARAFAC were compared to the one obtained with supervised discriminant unfolded partial least squares (DU-PLS). The best discrimination was obtained with the supervised DU-PLS, which allowed the pairwise differentiation of the four pairs of investigated fibers.DU-PLS was then used to investigate weathering effects on the spectral features of cotton 400 pre-dyed with DB1, nylon 361 pre-dyed with AY17 and acrylic 864 pre-dyed with BG4. The investigated fibers were exposed to humid (Florida) and dry (Arizona) weathering conditions for three, six, nine and twelve months. In all cases, this algorithm was unable to differentiate non-exposed acrylic fibers from exposed acrylic fibers. DU-PLS was able to differentiate non-exposed cotton and nylon fibers from exposed fibers to Florida and Arizona weathering conditions. It was possible to determine the period of exposure to either Florida or Arizona conditions. It was also possible to discriminate between fibers exposed to Florida or Arizona weathering conditions for the same period of time. These results provide the foundation for future studies towards a non-destructive approach capable to provide information on the history of the fiber.
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Date Issued: 2016
Identifier: CFE0006838, ucf:51773
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006838

Title: Aggregation of Squaraine Dye Derivatives in Solid State Spin-coated Thin Films.
Creator: Daoudi, Mohammed, Belfield, Kevin, Miles, Delbert, Campiglia, Andres, Bhattacharya, Aniket, Rex, Matthew, University of Central Florida
Abstract / Description: Squaraine dyes have been the subject of intensive studies due their unusual electronic properties that make them good candidates for a wide range of applications in various technological fields. They are particularly promising in nonlinear optics, bioimaging for labeling and sensing of biomolecules, as sensitizers for solar energy harvesting in solar cells and organic photovoltaics, two-photon absorbing materials, near-infrared (NIR) emitting fluorescent probes, second harmonic generation...
Show moreSquaraine dyes have been the subject of intensive studies due their unusual electronic properties that make them good candidates for a wide range of applications in various technological fields. They are particularly promising in nonlinear optics, bioimaging for labeling and sensing of biomolecules, as sensitizers for solar energy harvesting in solar cells and organic photovoltaics, two-photon absorbing materials, near-infrared (NIR) emitting fluorescent probes, second harmonic generation organic dyes, and sensitizers for photodynamic therapy among others. In this dissertation, the aggregation behaviors and features of several squaraine dye derivatives in solid state thin films were studied and reported.In the first chapter of the dissertation, three squaraine dye derivatives with two and four hydroxy groups and with different N-alkyl amino donor substituents were synthesized and used as models to study aggregation behavior. Their UV-vis absorption, thermal properties, and photoluminescence properties were determined. The models with four hydroxy substituents exhibited higher thermal stability and melt at higher temperature compared to the dye with only two hydroxy substituents due to increased hydrogen bonding. The UV-vis absorption and photoluminescence properties in liquid solution at room temperature were found to be similar.In the second chapter, the squaraine dyes, 2,4-bis [4-(N,N-di-n-pentylamino)-2-hydroxyphenyl] squaraine [SQC5(OH)2], 2,4-bis [4-(N,N-di-n-pentylamino)-2,4-hydroxyphenyl] squaraine [SQC5(OH)4 n], and 2,4-bis [4-(N,N-di-isopentylamino)-2,4-hydroxyphenyl] squaraine [SQC5(OH)4 b], where (")n(") and (")b(") stand for normal or linear and branched alkyl groups, respectively, were investigated to study their aggregation in solid state thin film form using UV-vis absorption spectroscopy. The investigation revealed significant differences in aggregation behaviors and features. The dye SQC5(OH)2 mainly exhibited J-type aggregation with an intense absorption band in the NIR region. In contrast, the SQC5(OH)4 n and SQC5(OH)4 b compounds mainly exhibited H-type aggregation, characterized by less intense and blue shifted absorption bands. The third chapter presents the kinetic study conducted on the squaraine dye derivative 2,4-bis [4-(N,N-di-n-pentylamino)-2-hydroxyphenyl] squaraine [SQC5(OH)2] in solid state spin-coated thin films. The study revealed the formation of J-aggregates with bands at 767 nm at room temperature. This aggregate was temperature dependent. It was transformed into H-aggregates as the temperature increased. The activation energy of the decay (transformation) process was found to be 91.2 kJ. The values of ?H and ?S are 88.4 kJ/mol and 48.2 J/K.mol, respectively, indicating the J-aggregate of SQC5(OH)2 was a kinetic product while the H-aggregate was thermondynamically more stable.
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Date Issued: 2015
Identifier: CFE0005778, ucf:50064
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005778

Title: Degradation of Hydrazine and Monomethylhydrazine for Fuel Waste Streams using Alpha-ketoglutaric Acid.
Creator: Franco, Carolina, Yestrebsky, Cherie, Clausen, Christian, Rex, Matthew, Harper, James, Duranceau, Steven, University of Central Florida
Abstract / Description: Alpha-ketoglutaric acid (AKGA) is an organic acid important for the metabolism of essential amino acids as well as for the transfer of cellular energy. It is a precursor of glutamic acid which is produced by the human body during the Krebs Cycle. AKGA has a specific industrial interest as it can be taken as a dietary supplement and is also widely used as a building block in chemical synthesis.Collectively termed as hydrazine (HZs), hydrazine (HZ) and monomethylhydrazine (MMH) are hypergolic...
Show moreAlpha-ketoglutaric acid (AKGA) is an organic acid important for the metabolism of essential amino acids as well as for the transfer of cellular energy. It is a precursor of glutamic acid which is produced by the human body during the Krebs Cycle. AKGA has a specific industrial interest as it can be taken as a dietary supplement and is also widely used as a building block in chemical synthesis.Collectively termed as hydrazine (HZs), hydrazine (HZ) and monomethylhydrazine (MMH) are hypergolic fuels that do not need an ignition source to burn. Because of the particular HZs' characteristics the National Aeronautics and Space Administration (NASA) at Kennedy Space Center (KSC) and the US Air Force at Cape Canaveral Air Force Station (CCAFS) consistently use HZ and MMH as hypergolic propellants. These propellants are highly reactive and toxic, and have carcinogenic properties. The handling, transport, and disposal of HZ waste are strictly regulated under the Resource Conservation and Recovery Act (RCRA) to protect human health and the environment. Significant quantities of wastewater containing residuals of HZ and MMH are generated at KSC and CCAFS that are subsequently disposed off-site as hazardous waste. This hazardous waste is shipped for disposal over public highways, which presents a potential threat to the public and the environment in the event of an accidental discharge in transit. NASA became aware of research done using AKGA to neutralize HZ waste. This research indicated that AKGA transformed HZ in an irreversible reaction potentially leading to the disposal of the hypergols via the wastewater treatment facility located at CCAFS eliminating the need to transport most of the HZ waste off-site.New Mexico Highlands University (NMHU) has researched this transformation of HZ by reaction with AKGA to form stabilized pyridazine derivatives. NMHU's research suggests that the treatment of HZ and MMH using AKGA is an irreversible reaction; once the reaction takes place, HZ and/or MMH cannot re-form from the byproducts obtained. However, further knowledge relating to the ultimate end products of the reaction, and their effects on human health and the environment, must still be addressed. The known byproduct of the AKGA/HZ neutralization reaction is 6-oxo-1,4,5,6-tetrahydro-pyridazine-3-carboxylic acid (PCA), and the byproduct of the AKGA/MMH reaction is 1-methyl-6-oxo-4,5-dihydro-pyridazine-3-carboxylic acid (mPCA).This research addressed several primary areas of interest to further the potential use of AKGA for HZ and MMH neutralization: 1) isolation of the end-product of the MMH-AKGA degradation process, 1-methyl-6-oxo-4,5-dihydro-pyridazine-3-carboxylic acid (mPCA), and determination of several physical properties of this substance, 2) evaluation of the kinetics of the reaction of AKGA with HZ or MMH, 3) verification of the chemical mechanism for the reaction of the individual hypergols with AKGA, 4) determination of whether the addition of a silicone-based antifoaming agent (AF), citric acid (CA) and/or isopropyl alcohol (IPA) to the AKGA and HZ or MMH solution interferes with the degradation reaction, 4) application of laboratory bench scale experiments in field samples, and 5) determination of the reaction enthalpy of these reactions.
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Date Issued: 2014
Identifier: CFE0005493, ucf:50334
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005493

Title: Novel Developments on the Extraction and Analysis of Polycyclic Aromatic Hydrocarbons in Environmental Samples.
Creator: Wilson, Walter, Campiglia, Andres, Belfield, Kevin, Rex, Matthew, Harper, James, Hoffman, Jay, University of Central Florida
Abstract / Description: This dissertation focuses on the development of analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) in water samples. Chemical analysis of PAHs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Among the hundreds of PAHs present in the environment, the U.S. Environmental Protection Agency (EPA) lists sixteen as "Consent Decree" priority pollutants. Their routine monitoring in...
Show moreThis dissertation focuses on the development of analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) in water samples. Chemical analysis of PAHs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Among the hundreds of PAHs present in the environment, the U.S. Environmental Protection Agency (EPA) lists sixteen as "Consent Decree" priority pollutants. Their routine monitoring in environmental samples is recommended to prevent human contamination risks.A primary route of human exposure to PAHs is the ingestion of contaminated water. The rather low PAH concentrations in water samples make the analysis of the sixteen priority pollutants particularly challenging. Current EPA methodology follows the classical pattern of sample extraction and chromatographic analysis. The method of choice for PAHs extraction and pre-concentration is solid-phase extraction (SPE). PAHs determination is carried out via high-performance liquid chromatography (HPLC) or gas chromatography/mass spectrometry (GC/MS). When HPLC is applied to highly complex samples, EPA recommends the use of GC/MS to verify compound identification and to check peak-purity of HPLC fractions. Although EPA methodology provides reliable data, the routine monitoring of numerous samples via fast, cost effective and environmentally friendly methods remains an analytical challenge. Typically, 1 L of water is processed through the SPE device in approximately 1 h. The rather large water volume and long sample processing time are recommended to reach detectable concentrations and quantitative removal of PAHs from water samples. Chromatographic elution times of 30 (-) 60 min are typical and standards must be run periodically to verify retention times. If concentrations of targeted PAHs are found to lie outside the detector's response range, the sample must be diluted (or concentrated), and the process repeated. In order to prevent environmental risks and human contamination, the routine monitoring of the sixteen EPA-PAHs is not sufficient anymore. Recent toxicological studies attribute a significant portion of the biological activity of PAH contaminated samples to the presence of high molecular weight (HMW) PAHs, i.e. PAHs with MW ? 300. Because the carcinogenic properties of HMW-PAHs differ significantly from isomer to isomer, it is of paramount importance to determine the most toxic isomers even if they are present at much lower concentrations than their less toxic isomers. Unfortunately, established methodology cannot always meet the challenge of specifically analyzing HMW-PAHs at the low concentration levels of environmental samples. The main problems that confront classic methodology arise from the relatively low concentration levels and the large number of structural isomers with very similar elution times and similar, possibly even virtually identical, fragmentation patterns. This dissertation summarizes significant improvements on various fronts. Its first original component deals with the unambiguous determination of four HMW-PAHs via laser-excited time-resolved Shpol'skii spectroscopy (LETRSS) without previous chromatographic separation. The second original component is the improvement of a relatively new PAH extraction method - solid-phase nanoextraction (SPNE) - which uses gold nanoparticles as extracting material for PAHs. The advantages of the improved SPNE procedure are demonstrated for the analysis of EPA-PAHs and HMW-PAHs in water samples via GC/MS and LETRSS, respectively.
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Date Issued: 2014
Identifier: CFE0005443, ucf:50384
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005443

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