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Title: Study of Polychlorinated Biphenyl Dechlorination by Zero Valent Magnesium With and Without Activated Carbon in Acidified Ethanol-Ethyl Lactate System.
Creator: Zullo, Fiona, Yestrebsky, Cherie, Clausen, Christian, Campiglia, Andres, Zou, Shengli, Duranceau, Steven, University of Central Florida
Abstract / Description: Polychlorinated biphenyls (PCBs) are synthetic organic chemicals that ca de detected in the environment worldwide. PCBs were banned in the U.S in 1979 owing to their toxicity and persistence in the environment. Today PCBs are classified as human carcinogens and are among the top ten of the U.S Environmental Protection Agency's (EPA) most toxic chemicals. Many researchers have shown soil to be contaminated with PCBs at concentrations as high as 750 ppm. Given the toxicity of PCBs, there is an...
Show morePolychlorinated biphenyls (PCBs) are synthetic organic chemicals that ca de detected in the environment worldwide. PCBs were banned in the U.S in 1979 owing to their toxicity and persistence in the environment. Today PCBs are classified as human carcinogens and are among the top ten of the U.S Environmental Protection Agency's (EPA) most toxic chemicals. Many researchers have shown soil to be contaminated with PCBs at concentrations as high as 750 ppm. Given the toxicity of PCBs, there is an urgent need to extract and degrade such chemicals from contaminated soil in a cost effective way. Prior work revealed a novel method of degradation of PCBs via hydrodehalogenation with zero-valent magnesium in acidified ethanol and ethyl lactate as a solvent system. Even though this degradation method gave satisfactory results for PCB degradation, this system cannot tolerate more than 3% water in order to degrade PCBs, limiting its application to wet soil field samples. In the present work a new system of acidified ethanol and ethyl lactate with ZVMg over activated carbon was developed which shows promising results on the degradation process of PCBs even with water present in the system. A detailed study of the byproducts formed in the dechlorination process and a degradation pathway, along with the activity of the system over time, are presented in this research.Also, a study of the mechanism involved in this reaction was done via computational methods to elucidate a mechanism pathway. It was demonstrated that these reactions are exothermic and involved two transition states, the formation of the first transition state being the limiting step of this reaction.The torsion angle of the PCB congeners was also shown to be an extremely important factor in order to be able to use activated carbon as part of the remediation process. These findings allow a greater understanding of the reductive dechlorination assisted by ZVMg and will help to improve the remediation process in field samples.
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Date Issued: 2016
Identifier: CFE0006205, ucf:51105
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006205

Title: Fabrication and Study of Graphene-Based Nanocomposites for Sensing and Energy Applications.
Creator: McInnis, Matthew, Zhai, Lei, Yestrebsky, Cherie, Zou, Shengli, Blair, Richard, Chen, Quanfang, University of Central Florida
Abstract / Description: Graphite is an allotrope of carbon made up of atomically thin sheets, each covalently bound together, forming a ?-conjugated network. An individual layer, called graphene, has extraordinary electrical, thermal and physical properties that provide the opportunity for innovating new functional composites. Graphene can be produced directly on a metallic substrate by chemical vapor deposition or by chemical oxidation of graphite, forming a stable aqueous suspension of graphene oxide (GO), which...
Show moreGraphite is an allotrope of carbon made up of atomically thin sheets, each covalently bound together, forming a ?-conjugated network. An individual layer, called graphene, has extraordinary electrical, thermal and physical properties that provide the opportunity for innovating new functional composites. Graphene can be produced directly on a metallic substrate by chemical vapor deposition or by chemical oxidation of graphite, forming a stable aqueous suspension of graphene oxide (GO), which allows for convenient solution processing techniques. For the latter, after thermal or chemical reduction, much of the properties of the starting graphene re-emerge due to the reestablishment of ?-conjugation. The ?-conjugated basal plane of graphene has been shown to influence the crystallization of ?-conjugated polymers, providing thermodynamically strong nucleation sites through the relatively strong ?-? interactions. These polymers can homocrystallize into 1-D filaments, but when nucleated from graphene, the orientation and geometry can be controlled producing hierarchical structures containing an electrical conductor decorated with wires of semi-conducting polymer. The resulting structures and crystallization kinetics of the conjugated polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT) nucleated by graphene was studied. Further, field-effect transistors were developed using graphene as both the electrodes and the polymer crystallization surface to directly grow P3HT nanowires as the active material. This direct crystallization technique lead to higher charge mobility and higher on-off ratios, and this result was interpreted in terms of the morphology and polymer-graphene interface.Besides these thin-film technologies, neat GO suspensions can be lyophilized to produce monolithic, free-standing aerogels and then reduced to produce an electrically conductive porous material with a surface area greater than 1000 m2/g. The present research focuses on functionalizing the aerogel surfaces with metal nanoparticles to increase electrical conductivity and to impart functionality. Functionalization was carried out by adding a metal salt as a precursor and a chelating agent to inhibit GO flocculation. The GO and metal salt were simultaneously reduced to form rGO aerogels homogeneously loaded with metal nanoparticles. The size and distribution of these nanoparticles was controlled by concentration and chelating agent identity and abundance. Optimum aerogel formulations were used as a functioning and reversible conductometric hydrogen gas sensor and as an anode in an asymmetric supercapacitor with excellent properties.
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Date Issued: 2015
Identifier: CFE0006227, ucf:51066
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006227

Title: Trace Contaminant Control: An In-Depth Study of a Silica-Titania Composite for Photocatalytic Remediation of Closed-Environment Habitat Air.
Creator: Coutts, Janelle, Yestrebsky, Cherie, Clausen, Christian, Sigman, Michael, Elsheimer, Seth, Wheeler, Raymond, University of Central Florida
Abstract / Description: This collection of studies focuses on a photocatalytic oxidation (PCO) system for the oxidation of a model compound, ethanol (EtOH), using an adsorption-enhanced silica-titania composite (STC) as the photocatalyst. Studies are aimed at addressing the optimization of various parameters including light source, humidity, temperature, and possible poisoning events for use as part of a system for gaseous trace contaminant control in closed-environment habitats.The first goal was to distinguish the...
Show moreThis collection of studies focuses on a photocatalytic oxidation (PCO) system for the oxidation of a model compound, ethanol (EtOH), using an adsorption-enhanced silica-titania composite (STC) as the photocatalyst. Studies are aimed at addressing the optimization of various parameters including light source, humidity, temperature, and possible poisoning events for use as part of a system for gaseous trace contaminant control in closed-environment habitats.The first goal was to distinguish the effect of photon flux (i.e., photons per unit time reaching a surface) from that of photon energy (i.e., wavelength) of a photon source on the PCO of ethanol. Experiments were conducted in a bench-scale annular reactor packed with STC pellets and irradiated with either a UV-A fluorescent black light blue lamp (?peak = 365 nm) at its maximum light intensity or a UV-C germicidal lamp (?peak = 254 nm) at three levels of light intensity. The STC-catalyzed oxidation of ethanol was found to follow zero-order kinetics with respect to CO2 production, regardless of the photon source. Increased photon flux led to increased EtOH removal, mineralization, and oxidation rate accompanied by lower intermediate concentration in the effluent. The oxidation rate was higher in the reactor irradiated by UV-C than by UV-A (38.4 vs. 31.9 nM s-1) at the same photon flux, with similar trends for mineralization (53.9 vs. 43.4%) and photonic efficiency (63.3 vs. 50.1 nmol CO2 (&)#181;mol photons-1). UV-C irradiation also led to decreased intermediate concentration in the effluent compared to UV-A irradiation. These results demonstrated that STC-catalyzed oxidation is enhanced by both increased photon flux and photon energy.The effect of temperature and relative humidity on the STC-catalyzed degradation of ethanol was also determined using the UV-A light source at its maximum intensity. Increasing temperature from 25(&)deg;C to 65(&)deg;C caused a significant decrease in ethanol adsorption (47.1% loss in adsorption capacity); minimal changes in EtOH removal; and a dramatic increase in mineralization (37.3 vs. 74.8%), PCO rate (25.8 vs. 53.2 nM s-1), and photonic efficiency (42.7 vs. 82.5 nmol CO2 (&)#181;mol photons-1); as well as a decrease in intermediate acetaldehyde (ACD) evolution in the effluent. By elevating the reactor temperature to 45(&)deg;C, an ~32% increase in photonic efficiency was obtained over the use of UV-C irradiation at room temperature. Increasing the reactor temperature also allowed for increased energy usage efficiency by utilizing both the light and heat energy of the UV-A light source. Higher relative humidity (RH) also caused a significant decrease (16.8 vs. 6.0 mg EtOH g STC-1) in ethanol adsorption and dark adsorption 95% breakthrough times (48.5 vs.16.8 hours). Trends developed for ethanol adsorption correlated well with studies using methanol as the target VOC on a molar basis. At higher RH, ethanol removal and ACD evolution were increased while mineralization, PCO rate, and photonic efficiency were decreased. These studies allowed for the development of empirical formulas to approximate EtOH removal, PCO rate, mineralization, and ACD evolution based on the parameters (light intensity, temperature, and RH) assessed.Poisoning events included long-term exposure to low-VOC laboratory air and episodic spikes of either Freon 218 or hexamethylcyclotrisiloxane. To date, all poisoning studies have shown minimal (0-6%) decreases in PCO rates, mineralization, and minimal increases in ACD evolution, with little change in EtOH removal. These results show great promise for this technology as part of a trace contaminant control system for niche applications such as air processing onboard the ISS or other new spacecrafts.
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Date Issued: 2013
Identifier: CFE0005092, ucf:50741
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005092

Title: Non-Destructive Analysis of Trace Textile Fiber Evidence via Room-Temperature Fluorescence Spectrocopy.
Creator: Appalaneni, Krishnaveni, Campiglia, Andres, Belfield, Kevin, Sigman, Michael, Yestrebsky, Cherie, Schulte, Alfons, University of Central Florida
Abstract / Description: Forensic fiber evidence plays an important role in many criminal investigations. Non-destructive techniques that preserve the physical integrity of the fibers for further court examination are highly valuable in forensic science. 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. When fibers cannot...
Show moreForensic fiber evidence plays an important role in many criminal investigations. Non-destructive techniques that preserve the physical integrity of the fibers for further court examination are highly valuable in forensic science. 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. When fibers cannot be discriminated by non-destructive tests, the next reasonable step is to extract the questioned and known fibers for dye analysis with a more selective technique such as high-performance liquid chromatography (HPLC) and/or gas chromatography-mass spectrometry (GC-MS). The common denominator among chromatographic techniques is to primarily focus on the dyes used to color the fibers and do not investigate other potential discriminating components present on the fiber. Differentiating among commercial dyes with very similar chromatographic behaviors and almost identical absorption spectra and/or fragmentation patterns is a challenging task.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 investigate the contribution of intrinsic fluorescence impurities (-) i.e. impurities imbedded into the fibers during fabrication of garments - as a reproducible source of fiber comparison. Differentiation of visually indistinguishable fibers is achieved by comparing excitation-emission matrices (EEMs) recorded from single textile fibers with the aid of a commercial spectrofluorimeter coupled to an epi-fluorescence microscope. Statistical data comparison was carried out via principal component analysis. An application of this statistical approach is demonstrated using challenging dyes with similarities both in two-dimensional absorbance spectra and in three dimensional EEM data. High accuracy of fiber identification was observed in all the cases and no false positive identifications were observed at 99% confidence levels.
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Date Issued: 2013
Identifier: CFE0004808, ucf:49740
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004808

Title: Assessment of molecular interactions via magnetic relaxation: a quest for inhibitors of the anthrax toxin.
Creator: Santiesteban, Oscar, Perez Figueroa, Jesus, Liao, Yi, Yestrebsky, Cherie, Hampton, Michael, Lambert, Stephen, University of Central Florida
Abstract / Description: Anthrax is severe disease caused by the gram-positive Bacillus anthracis that can affect humans with deadly consequences. The disease propagates via the release of bacterial spores that can be naturally found in animals or can be weaponized and intentionally released into the atmosphere in a terrorist attack. Once inhaled, the spores become activated and the anthrax bacterium starts to reproduce and damage healthy macrophages by the release of the anthrax toxin. The anthrax toxin is composed...
Show moreAnthrax is severe disease caused by the gram-positive Bacillus anthracis that can affect humans with deadly consequences. The disease propagates via the release of bacterial spores that can be naturally found in animals or can be weaponized and intentionally released into the atmosphere in a terrorist attack. Once inhaled, the spores become activated and the anthrax bacterium starts to reproduce and damage healthy macrophages by the release of the anthrax toxin. The anthrax toxin is composed of three virulent factors: (i) anthrax protective antigen (APA), (ii) anthrax lethal factor (ALF), and (iii) anthrax edema factor (AEF) that work in harmony to effectuate the lethality associated with the disease. Out of the two internalized factors, ALF has been identified to play a critical role in cell death. Studies in animals have shown that mice infected with an anthrax strain lacking ALF survive the infection whereas when ALF is present the survivability of the mice is eliminated. Although the current therapy for anthrax is antibiotic treatment, modern medicine faces some critical limitations when combating infections. Antibiotics have proven very efficient in eliminating the bacterial infection but they lack the ability to destroy or inhibit the toxins released by the bacteria. This is a significant problem since ALF can remain active in the body for days after the infection is eliminated with no way of inhibiting its destructive effects. The use of inhibitors of ALF is an attractive method to treat the pathogenesis of anthrax infections. Over the last decade several inhibitors of the enzymatic activity of ALF have been identified. In order to identify inhibitors of ALF a variety of screening approaches such as library screenings, Mass Spectroscopy- based screenings and scaffold-based NMR screening have been used. Results from these screening have yielded mainly small molecules that can inhibit ALF in low micromolar to nanomolar concentrations. Yet, although valuable, these results have very little significance with regards to treating ALF in a real-life scenario since pharmaceutical companies are not willing to invest in further developing these inhibitors. Furthermore, the low incidence of inhalation anthrax, the lack of a market for an ALF inhibitor, and the expenses associated with the approval process of the FDA, have hindered the motivation of pharmaceutical companies to pursuit these kind of drugs. Therefore we have screened a small-molecule library of FDA approved drugs and common molecules in order to identify currently approved FDA drugs that can also inhibit ALF (Chapter III). The screening revealed that five molecules: sulindac, fusaric acid, naproxen, ketoprofen and ibuprofen bound to either ALF or APA with sulindac binding both. Additionally, we have developed a nanoparticle-based screening method that assesses molecular interactions by magnetic relaxation changes (Chapter II). Using this assay, we were able to accurately measure the dissociation constants of different interactions between several ligands and macromolecules. Moreover, we have used computational docking studies to predict the binding site of the identified molecules on the ALF or APA (Chapter IV). These studies predicted that two molecules sulindac and fusaric acid could be potential inhibitors of ALF since they bind at the enzymatic pocket. As a result, we tested the inhibitory potential of these molecules as well as that of the metabolic derivatives of sulindac (Chapter V). Results from these studies provided conclusive evidence that fusaric acid and sulindac were both strong inhibitors of ALF. Furthermore, the metabolic derivatives of sulindac, sulindac sulfide and sulindac sulfone also inhibited ALF. Overall, taking together these results we have discovered the alternate use of a currently used drug for the treatment of ALF pathogenesis.
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Date Issued: 2012
Identifier: CFE0004794, ucf:49745
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004794

Title: A Study of the Degradative Capabilities of the Bimetallic System: Mg(Pd/C) as Applied in the Destruction of Decafluoropentane, an Environmental Contaminant.
Creator: Tomlin, Douglas, Clausen, Christian, Yestrebsky, Cherie, Hampton, Michael, Elsheimer, Seth, Griffin, Timothy, University of Central Florida
Abstract / Description: Pollution from hydrofluorocarbons (HFCs) poses a serious challenge to the environmental community. Released from industrial operations, they have contaminated both the atmosphere and groundwater and are considered persistent in both media. For over the past 20 years, the practice of synthesizing HFCs as alternatives to chlorofluorocarbons (CFCs) has been conducted in an effort to reverse the effects of stratospheric ozone layer depletion. HFCs also exhibit desirable properties as precision...
Show morePollution from hydrofluorocarbons (HFCs) poses a serious challenge to the environmental community. Released from industrial operations, they have contaminated both the atmosphere and groundwater and are considered persistent in both media. For over the past 20 years, the practice of synthesizing HFCs as alternatives to chlorofluorocarbons (CFCs) has been conducted in an effort to reverse the effects of stratospheric ozone layer depletion. HFCs also exhibit desirable properties as precision cleaning solvents due to their low surface energies but that use has lead to releases contaminating groundwater resulting in recalcitrant pollution in the form of dense non-aqueous phase liquids (DNAPLs). Results from studies requested by the EPA have shown HFCs to exhibit developmental and neurological damage in animal life along with their impact to humans remaining not completely understood. Therefore, the potential hazards of HFCs to human health and the environment necessitates the development of an effective and environmentally responsible technology for their remediation from groundwater. The National Aeronautics and Space Administration (NASA) has employed the use of various halogenated solvents in its spacecraft cleaning operations at its facilities for many years and in that time experienced accidental releases which eventually resulted in environmental contamination. Many of the organic solvents employed in these operations consisted of halogenated compounds with most being partially chlorinated and fluorinated hydrocarbons. Through normal use and operation, releases of these materials found their way into the environs of atmosphere, soil and groundwater. Remediation of fluorinated compounds has not followed the successful path laid by clean-up technologies developed for their chlorinated counterparts. Fluorinated compounds are resistant however to those methods due to their unreactive nature stemming from the properties of the strong carbon-fluorine bond. This unique bonding property also ensures that their environmental persistence endures. One particular fluorinated groundwater contaminant, the HFC 1,1,1,2,2,3,4,5,5,5-decafluoropentane (DFP), which has been used by NASA since the late 1990's was selected as the focus of this study. For this study, various reductive metal systems were evaluated for their capability towards effective degradation of DFP. These included the metals: iron, magnesium, aluminum and zinc and several bimetallic alloys as well as on carbon support. Variations in protic solvent reaction media and acidic metal activation were also explored. The bimetallic reductive catalytic alloy Magnesium with Palladium on Carbon, Mg(Pd/C), in aqueous media proved to be the successful candidate with 100% conversion to simple hydrocarbons. Mechanistic evaluation for degradation is proposed via a series of stepwise catalytic hydrodefluorination reactions. Kinetic studies revealed degradation to obey second order reaction kinetics. Further study should be conducted optimizing an in situ groundwater delivery method for field application. Additionally, the developed technology should be assessed against other groundwater fluorocarbon pollutants; either as a method for remediating multiple fluorinated polluted sites or as a polishing agent where all other pollutants have been abated.
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Date Issued: 2012
Identifier: CFE0004798, ucf:49742
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004798

Title: Selective Multivariate Applications in Forensic Science.
Creator: Rinke, Caitlin, Sigman, Michael, Campiglia, Andres, Yestrebsky, Cherie, Kuebler, Stephen, Richardson, Martin, University of Central Florida
Abstract / Description: A 2009 report published by the National Research Council addressed the need for improvements in the field of forensic science. In the report emphasis was placed on the need for more rigorous scientific analysis within many forensic science disciplines and for established limitations and determination of error rates from statistical analysis. This research focused on multivariate statistical techniques for the analysis of spectral data obtained for multiple forensic applications which include...
Show moreA 2009 report published by the National Research Council addressed the need for improvements in the field of forensic science. In the report emphasis was placed on the need for more rigorous scientific analysis within many forensic science disciplines and for established limitations and determination of error rates from statistical analysis. This research focused on multivariate statistical techniques for the analysis of spectral data obtained for multiple forensic applications which include samples from: automobile float glasses and paints, bones, metal transfers, ignitable liquids and fire debris, and organic compounds including explosives. The statistical techniques were used for two types of data analysis: classification and discrimination. Statistical methods including linear discriminant analysis and a novel soft classification method were used to provide classification of forensic samples based on a compiled library. The novel soft classification method combined three statistical steps: Principal Component Analysis (PCA), Target Factor Analysis (TFA), and Bayesian Decision Theory (BDT) to provide classification based on posterior probabilities of class membership. The posterior probabilities provide a statistical probability of classification which can aid a forensic analyst in reaching a conclusion. The second analytical approach applied nonparametric methods to provide the means for discrimination between samples. Nonparametric methods are performed as hypothesis test and do not assume normal distribution of the analytical figures of merit. The nonparametric permutation test was applied to forensic applications to determine the similarity between two samples and provide discrimination rates. Both the classification method and discrimination method were applied to data acquired from multiple instrumental methods. The instrumental methods included: Laser Induced-Breakdown Spectroscopy (LIBS), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, and Gas Chromatography-Mass Spectrometry (GC-MS). Some of these instrumental methods are currently applied to forensic applications, such as GC-MS for the analysis of ignitable liquid and fire debris samples; while others provide new instrumental methods to areas within forensic science which currently lack instrumental analysis techniques, such as LIBS for the analysis of metal transfers. The combination of the instrumental techniques and multivariate statistical techniques is investigated in new approaches to forensic applications in this research to assist in improving the field of forensic science.
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Date Issued: 2012
Identifier: CFE0004628, ucf:49942
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004628

Title: Assessing Biofiltration Pretreatment for Ultrafiltration Membrane Processes.
Creator: Cumming, Andrea, Duranceau, Steven, Cooper, David, Randall, Andrew, Wang, Dingbao, Yestrebsky, Cherie, University of Central Florida
Abstract / Description: An engineered biological filtration (biofiltration) process treating a nutrient-enriched, low-alkalinity, organic-laden surface water downstream of conventional coagulation-clarification and upstream of an ultrafiltration (UF) membrane process was assessed for its treatment effectiveness. The impact of biofiltration pretreatment on UF membrane performance was evaluated holistically by investigating the native source water chemistry and extending the analysis into the drinking water...
Show moreAn engineered biological filtration (biofiltration) process treating a nutrient-enriched, low-alkalinity, organic-laden surface water downstream of conventional coagulation-clarification and upstream of an ultrafiltration (UF) membrane process was assessed for its treatment effectiveness. The impact of biofiltration pretreatment on UF membrane performance was evaluated holistically by investigating the native source water chemistry and extending the analysis into the drinking water distribution system. The biofiltration process was also compared in treatment performance to two alternative pretreatment technologies, including magnetic ion exchange (MIEX(&)#174;) and granular activated carbon (GAC) adsorption.The MIEX(&)#174;, GAC adsorption, and biologically active carbon (BAC) filtration pretreatments were integrated with conventional pretreatment then compared at the pilot-scale. Comparisons were based on collecting data regarding operational requirements, dissolved organic carbon (DOC) reduction, regulated disinfection byproduct (DBP) formation, and improvement on the downstream UF membrane operating performance. UF performance, as measured by the temperature corrected specific flux or mass transfer coefficient (MTC), was determined by calculating the percent MTC improvement relative to the existing conventional-UF process that served as the control. The pretreatment alternatives were further evaluated based on cost and non-cost considerations.Compared to the MIEX(&)#174; and GAC pretreatment alternatives, which achieved effective DOC removal (40 and 40 percent, respectively) and MTC improvement (14 and 30 percent, respectively), the BAC pretreatment achieved the lowest overall DOC removal (5 percent) and MTC improvement (4.5 percent). While MIEX(&)#174; relies on anion exchange and GAC relies on adsorption to target DOC removal, biofiltration uses microorganisms attached on the filter media to remove biodegradable DOC.Two mathematical models that establish an empirical relationship between the MTC improvement and the dimensionless alkalinity to substrate (ALK/DOC) ratio were developed. By combining the biofiltration results from the present research with findings of previous studies, an empirical relationship between the MTC improvement versus the ALK/DOC ratio was modeled using non-linear regression in Minitab(&)#174;. For surface water sources, UF MTC improvement can be simulated as a quadratic or Gaussian distribution function of the gram C/gram C dimensionless ALK/DOC ratio. According to the newly developed empirical models, biofiltration performance is optimized when the alkalinity to substrate ratio is between 10 and 14. For the first time a model has thus been developed that allows for a predictive means to optimize the operation of biofiltration as a pretreatment prior to UF membrane processes treating surface water.
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Date Issued: 2015
Identifier: CFE0005595, ucf:50260
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005595

Title: Chemical Analysis, Databasing, and Statistical Analysis of Smokeless Powders for Forensic Application.
Creator: Dennis, Dana-Marie, Sigman, Michael, Campiglia, Andres, Yestrebsky, Cherie, Fookes, Barry, Ni, Liqiang, University of Central Florida
Abstract / Description: Smokeless powders are a set of energetic materials, known as low explosives, which are typically utilized for reloading ammunition. There are three types which differ in their primary energetic materials; where single base powders contain nitrocellulose as their primary energetic material, double and triple base powders contain nitroglycerin in addition to nitrocellulose, and triple base powders also contain nitroguanidine. Additional organic compounds, while not proprietary to specific...
Show moreSmokeless powders are a set of energetic materials, known as low explosives, which are typically utilized for reloading ammunition. There are three types which differ in their primary energetic materials; where single base powders contain nitrocellulose as their primary energetic material, double and triple base powders contain nitroglycerin in addition to nitrocellulose, and triple base powders also contain nitroguanidine. Additional organic compounds, while not proprietary to specific manufacturers, are added to the powders in varied ratios during the manufacturing process to optimize the ballistic performance of the powders. The additional compounds function as stabilizers, plasticizers, flash suppressants, deterrents, and opacifiers. Of the three smokeless powder types, single and double base powders are commercially available, and have been heavily utilized in the manufacture of improvised explosive devices.Forensic smokeless powder samples are currently analyzed using multiple analytical techniques. Combined microscopic, macroscopic, and instrumental techniques are used to evaluate the sample, and the information obtained is used to generate a list of potential distributors. Gas chromatography (-) mass spectrometry (GC-MS) is arguably the most useful of the instrumental techniques since it distinguishes single and double base powders, and provides additional information about the relative ratios of all the analytes present in the sample. However, forensic smokeless powder samples are still limited to being classified as either single or double base powders, based on the absence or presence of nitroglycerin, respectively. In this work, the goal was to develop statistically valid classes, beyond the single and double base designations, based on multiple organic compounds which are commonly encountered in commercial smokeless powders. Several chemometric techniques were applied to smokeless powder GC-MS data for determination of the classes, and for assignment of test samples to these novel classes. The total ion spectrum (TIS), which is calculated from the GC-MS data for each sample, is obtained by summing the intensities for each mass-to-charge (m/z) ratio across the entire chromatographic profile. A TIS matrix comprising data for 726 smokeless powder samples was subject to agglomerative hierarchical cluster (AHC) analysis, and six distinct classes were identified. Within each class, a single m/z ratio had the highest intensity for the majority of samples, though the m/z ratio was not always unique to the specific class. Based on these observations, a new classification method known as the Intense Ion Rule (IIR) was developed and used for the assignment of test samples to the AHC designated classes.Discriminant models were developed for assignment of test samples to the AHC designated classes using k-Nearest Neighbors (kNN) and linear and quadratic discriminant analyses (LDA and QDA, respectively). Each of the models were optimized using leave-one-out (LOO) and leave-group-out (LGO) cross-validation, and the performance of the models was evaluated by calculating correct classification rates for assignment of the cross-validation (CV) samples to the AHC designated classes. The optimized models were utilized to assign test samples to the AHC designated classes. Overall, the QDA LGO model achieved the highest correct classification rates for assignment of both the CV samples and the test samples to the AHC designated classes.In forensic application, the goal of an explosives analyst is to ascertain the manufacturer of a smokeless powder sample. In addition, knowledge about the probability of a forensic sample being produced by a specific manufacturer could potentially decrease the time invested by an analyst during investigation by providing a shorter list of potential manufacturers. In this work, Bayes' Theorem and Bayesian Networks were investigated as an additional tool to be utilized in forensic casework. Bayesian Networks were generated and used to calculate posterior probabilities of a test sample belonging to specific manufacturers. The networks were designed to include manufacturer controlled powder characteristics such as shape, color, and dimension; as well as, the relative intensities of the class associated ions determined from cluster analysis. Samples were predicted to belong to a manufacturer based on the highest posterior probability. Overall percent correct rates were determined by calculating the percentage of correct predictions; that is, where the known and predicted manufacturer were the same. The initial overall percent correct rate was 66%. The dimensions of the smokeless powders were added to the network as average diameter and average length nodes. Addition of average diameter and length resulted in an overall prediction rate of 70%.
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Date Issued: 2015
Identifier: CFE0005784, ucf:50059
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005784

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: 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.
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Date Issued: 2014
Identifier: CFE0005513, ucf:50308
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005513

Title: Iron Molybdenum Cofactor: Catalyst in Dihydrogen Production and NifEN's Role in the FeMo-co Biosynthetic Pathway.
Creator: Maxwell, Deborah, Clausen, Christian, Yestrebsky, Cherie, Hampton, Michael, Sigman, Michael, University of Central Florida
Abstract / Description: Humankind's tremendous industrial and technological progress over the last two centuries has been driven by the natural abundance and availability of fossil fuels. As those reserves deplete, the prudent course of action would be to develop other readily available fuel sources. Some research efforts using biomolecules involve the hydrogenases and nitrogenases with the goal of evolving dihydrogen. At the nitrogenase active site, the iron-molybdenum cofactor (FeMo-co) catalyzes the reduction of...
Show moreHumankind's tremendous industrial and technological progress over the last two centuries has been driven by the natural abundance and availability of fossil fuels. As those reserves deplete, the prudent course of action would be to develop other readily available fuel sources. Some research efforts using biomolecules involve the hydrogenases and nitrogenases with the goal of evolving dihydrogen. At the nitrogenase active site, the iron-molybdenum cofactor (FeMo-co) catalyzes the reduction of dinitrogen and protons to form ammonia and dihydrogen.Toward the goal of producing dihydrogen passively as an alternative fuel, a novel advanced material has been developed. CdSe nanoparticles complexed with FeMo-co, in both aqueous and organic solvent systems showed complex formation. When the system was interrogated by EPR spectroscopy, evidence of electron transfer was observed. The CdSe-MSA?NafY?FeMo-co system when illuminated with visible light evolved dihydrogen consistently in four different experimental sets under the same reaction conditions. NifEN protein plays an important role in the biosynthesis of FeMo-co in addition to the involvement of NifU, NifS, NifB, NifX, NifH and NafY. After NifB synthesizes a FeMo-co precursor, 6-Fe NifB-co, NifEN further incorporates additional Fe, S, Mo, and (R)-homocitrate to complete the synthesis of FeMo-co. Molybdenum is provided to NifEN as its oxoanion, Mo(VI)O42-; however, in FeMo-co molybdenum is in the oxidation state of Mo(IV). EPR spectroscopic investigation of NifEN turnover samples showed a signal at g = 2.00 that was dependent on molybdate concentration. Power and temperature profiles gave evidence that the g = 2.00 EPR signal was distinct from the Fe-S clusters in NifEN. The species observed at g = 2.00 was assigned to the reduction of Mo(VI) to Mo(V). How to utilize the effectiveness of FeMo-co and complex it to photoactive materials for the purpose of evolving dihyrogen upon illumination, thus providing a sustainable alternative energy source is one subject of this dissertation. A related subject is to gain an understanding of the biosynthetic pathway of FeMo-co by investigation of NifEN turnover experiments. This understanding should contribute towards the development of improved catalysts for meeting future energy demands.
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Date Issued: 2012
Identifier: CFE0004623, ucf:49917
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004623

Title: Development of Novel Redox Sensors and Processes Towards Biological Applications.
Creator: Patel, Jigna, Yestrebsky, Cherie, Clausen, Christian, Hampton, Michael, Harper, James, Diaz, Diego, University of Central Florida
Abstract / Description: Research on the cure and early detection of diseases such as diabetes, Alzheimer's, and Parkinson's is becoming of great interest due to the increasing number of people affected by them every year. An accurate and quick detection of various damaging species is highly critical in treatments of such diseases not only for exploring possible cures but also for early detection. If these diseases are detected during the initial stages than the possibility of curing them is much higher. Motivated by...
Show moreResearch on the cure and early detection of diseases such as diabetes, Alzheimer's, and Parkinson's is becoming of great interest due to the increasing number of people affected by them every year. An accurate and quick detection of various damaging species is highly critical in treatments of such diseases not only for exploring possible cures but also for early detection. If these diseases are detected during the initial stages than the possibility of curing them is much higher. Motivated by this, many researchers today have developed numerous types of sensing devices that can detect various physiological and biological compounds. However, most of these sensors are enzyme based. They have several setbacks such as the lack of sensitivity, restricted selectivity, short shelf life, and biological fouling. To overcome these obstacles, we examine the use of nanoceria modified Pt and Au electrodes for the detection of glucose and reactive oxygen species such as hydrogen peroxide. Amperometric detection of glucose and hydrogen peroxide is critical for biological applications for diabetes and possible Alzheimer's and Parkinson's patients. This dissertation focuses on the exploration of non-enzymatic detection of glucose and reactive oxygen species which has the prospective to be used for biological applications, in addition to an investigation of an odor control technology that uses these reactive oxygen species for the treatment of wastewater plants. The combination of bi-metallic composites with nanoceria showed increased oxidation ability towards glucose and hydrogen peroxide. The following dissertation expands on the relationship between bi-metallic nanoceria composite materials and its electro-oxidation of glucose and hydrogen peroxide towards biological sensing along with an investigation of an odor control technology that utilizes generates hydroxyl radical fine particle mist for the degradation of hydrogen sulfide odor in wastewater treatment plants.
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Date Issued: 2013
Identifier: CFE0005227, ucf:50585
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005227

Title: 1, 2, and 3 Dimension Carbon/Silicon Carbon Nitride Ceramic Composites.
Creator: Calderon Flores, Jean, Zhai, Lei, Campiglia, Andres, Yestrebsky, Cherie, Zou, Shengli, Khondaker, Saiful, University of Central Florida
Abstract / Description: Polymer-derived ceramics (PDCs) are exceptional ultra-high temperature and stable multifunctional class of materials that can be synthesized from a polymer precursor through thermal decomposition. The presented research focuses on 1-D nanofibers, 2-D films and 3-D bulk, carbon-rich silicon carbon nitride (SiCN) ceramics. 1-D nanofibers were prepared via electrospinning for light weight, flame retardant and conductive applications. The commercially available CerasetTM VL20, a liquid...
Show morePolymer-derived ceramics (PDCs) are exceptional ultra-high temperature and stable multifunctional class of materials that can be synthesized from a polymer precursor through thermal decomposition. The presented research focuses on 1-D nanofibers, 2-D films and 3-D bulk, carbon-rich silicon carbon nitride (SiCN) ceramics. 1-D nanofibers were prepared via electrospinning for light weight, flame retardant and conductive applications. The commercially available CerasetTM VL20, a liquid cyclosilazane pre-ceramic precursor, was mixed with polyacrylonitrile (PAN) in order to make the cyclosilazane electrospinnable. Carbon-rich PDC nano?bers were fabricated by electrospinning various ratios of PAN/cyclosilazane solutions followed by pyrolysis. Surface morphology of the electro spun nanofibers characterized by SEM show PDC nano?bers with diameters ranging from 100-300 nm. Also, thermal stability towards oxidation showed a 10% mass loss at 623oC. 2-D carbon/SiCN films were produced by drop-casting a mixture of PAN/cyclosilazane onto a glass slide followed by pyrolysis of the film. Samples ranging from 10:1 to 1:10 PAN:cyclosilazane were made by dissolving the solutes into DMF to produce solutions ranging from 1% to 12% by weight. Green, heat-stabilized, and pyrolyzed 8% films were examined with FTIR to monitor the change in chemical structure at each step of the ceramization. SEM shows that high PAN samples produced films with ceramic embedded spheroid components in a carbon matrix, while high cyclosilazane samples produced carbon embedded spheroid.Finally, this research focuses on the challenge of making fully dense, 3-D bulk PDCs materials. Here we present a composite of SiCN with reduced graphene oxide (rGO) aerogels as a route for fully dense bulk PDCs. Incorporation of the rGO aerogel matrix into the SiCN has its pros and cons. While it lowers the strength of the composite, it allows for fabrication of large bulk samples and an increase in the electrical conductivity of the PDC. The morphology, mechanical, electrical properties and thermal conductivity of graphene-SiCN composite with varying rGO aerogel loading (0.3-2.4%) is presented. The high temperature stability, high electrical conductivity and low thermal conductivity of these composites make them excellent candidates for thermoelectric applications. Generally, carbon-rich SiCN composites with improved thermal and electrical properties are of great importance to the aerospace and electronics industries due to their expected harsh operating environments.
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Date Issued: 2015
Identifier: CFE0005768, ucf:50095
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005768

Title: Forensic Application of Chemometric Analysis to Visible Absorption Spectra Collected from Dyed Textile Fibers.
Creator: Flores, Alejandra, Sigman, Michael, Yestrebsky, Cherie, Campiglia, Andres, Chumbimuni Torres, Karin, Ni, Liqiang, University of Central Florida
Abstract / Description: Forensic analysis of evidence consists of the comparison of physical, spectroscopic, or chemical characteristics of a questioned sample to a set of knowns. Currently, decisions as to whether or not the questioned sample can be associated or grouped with the knowns are left up to the discretion of the forensic analyst. The implications of these outcomes are presented as evidence to a jury in a court of law to determine if a defendant is guilty of committing a crime or not. Leading up to, and...
Show moreForensic analysis of evidence consists of the comparison of physical, spectroscopic, or chemical characteristics of a questioned sample to a set of knowns. Currently, decisions as to whether or not the questioned sample can be associated or grouped with the knowns are left up to the discretion of the forensic analyst. The implications of these outcomes are presented as evidence to a jury in a court of law to determine if a defendant is guilty of committing a crime or not. Leading up to, and since, the publication of the National Academy of Sciences (NAS) report entitled (")Strengthening Forensic Science in the United States: A Path Forward,(") the inadequacies of allowing potentially biased forensic opinion to carry such weight in the courtroom have been unmasked. This report exposed numerous shortcomings in many areas of forensic science, but also made recommendations on how to fortify the discipline. The main suggestions directed towards disciplines that analyze trace evidence include developing error rates for commonly employed practices and evaluating method reliability and validity.This research focuses on developing a statistical method of analysis for comparing visible absorption profiles collected from highly similarly colored textile fibers via microspectrophotometry (MSP). Several chemometric techniques were applied to spectral data and utilized to help discriminate fibers beyond the point where traditional methods of microscopical examination may fail. Because a dye's chemical structure dictates the shape of the absorption profile, two fibers dyed with chemically similar dyes can be very difficult to distinguish from one another using traditional fiber examination techniques. The application of chemometrics to multivariate spectral data may help elicit latent characteristics that may aid in fiber discrimination.The three sample sets analyzed include dyed fabric swatches (three pairs of fabrics were dyed with chemically similar dye pairs), commercially available blue yarns (100% acrylic), and denims fabrics (100% cotton). Custom dyed swatches were each dyed uniformly with a single dye whereas the dye formulation for both the yarns and denims is unknown. As a point for study, spectral comparisons were performed according to the guidelines published by the Standard Working Group for Materials Analysis (SWGMAT) Fiber Subgroup based on visual analysis only. In the next set of tests, principal components analysis (PCA) was utilized to reduce the dimensionality of the large multivariate data sets and to visualize the natural groupings of samples. Comparisons were performed using the resulting PCA scores where group membership of the questioned object was evaluated against the known objects using the score value as the distance metric. Score value is calculated using the score and orthogonal distances, the respective cutoff values based on a quantile percentage, and an optimization parameter, ?. Lastly, likelihood ratios (LR) were generated from density functions modelled from similarity values assessing comparisons between sample population data. R code was written in-house to execute all method of fiber comparisons described here. The SWGMAT method performed with 62.7% accuracy, the optimal accuracy rate for the score value method was 75.9%, and the accuracy rates for swatch-yarn and denim comparisons, respectively, are 97.7% and 67.1% when the LR method was applied.
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Date Issued: 2015
Identifier: CFE0005613, ucf:50212
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005613

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.
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Date Issued: 2013
Identifier: CFE0005222, ucf:50630
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005222

Title: The Behavior of Cerium Oxide Nanoparticles in Polymer Electrolyte Membranes in Ex-Situ and In-Situ Fuel Cell Durability Tests.
Creator: Pearman, Benjamin, Hampton, Michael, Blair, Richard, Clausen, Christian, Seal, Sudipta, Campiglia, Andres, Yestrebsky, Cherie, Mohajeri, Nahid, University of Central Florida
Abstract / Description: Fuel cells are known for their high efficiency and have the potential to become a major technology for producing clean energy, especially when the fuel, e.g. hydrogen, is produced from renewable energy sources such as wind or solar. Currently, the two main obstacles to wide-spread commercialization are their high cost and the short operational lifetime of certain components.Polymer electrolyte membrane (PEM) fuel cells have been a focus of attention in recent years, due to their use of...
Show moreFuel cells are known for their high efficiency and have the potential to become a major technology for producing clean energy, especially when the fuel, e.g. hydrogen, is produced from renewable energy sources such as wind or solar. Currently, the two main obstacles to wide-spread commercialization are their high cost and the short operational lifetime of certain components.Polymer electrolyte membrane (PEM) fuel cells have been a focus of attention in recent years, due to their use of hydrogen as a fuel, their comparatively low operating temperature and flexibility for use in both stationary and portable (automotive) applications.Perfluorosulfonic acid membranes are the leading ionomers for use in PEM hydrogen fuel cells. They combine essential qualities, such as high mechanical and thermal stability, with high proton conductivity. However, they are expensive and currently show insufficient chemical stability towards radicals formed during fuel cell operation, resulting in degradation that leads to premature failure. The incorporation of durability improving additives into perfluorosulfonic acid membranes is discussed in this work.Cerium oxide (ceria) is a well-known radical scavenger that has been used in the biological and medical field. It is able to quench radicals by facilely switching between its Ce(III) and Ce(IV) oxidation states.In this work, cerium oxide nanoparticles were added to perfluorosulfonic acid membranes and subjected to ex-situ and in-situ accelerated durability tests.The two ceria formulations, an in-house synthesized and commercially available material, were found to consist of crystalline particles of 2 (-) 5 nm and 20 (-) 150 nm size, respectively, that did not change size or shape when incorporated into the membranes.At higher temperature and relative humidity in gas flowing conditions, ceria in membranes is found to be reduced to its ionic form by virtue of the acidic environment. In ex-situ Fenton testing, the inclusion of ceria into membranes reduced the emission of fluoride, a strong indicator of degradation, by an order of magnitude with both liquid and gaseous hydrogen peroxide. In open-circuit voltage (OCV) hold fuel cell testing, ceria improved durability, as measured by several parameters such as OCV decay rate, fluoride emission and cell performance, over several hundred hours and influenced the formation of the platinum band typically found after durability testing.
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Date Issued: 2012
Identifier: CFE0004789, ucf:49731
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004789

Title: Remediation of Polychlorinated Biphenyl (PCB) Contaminated Building Materials Using Non-metal and Activated Metal Treatment Systems.
Creator: Legron-Rodriguez, Tamra, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Sigman, Michael, Chopra, Manoj, Quinn, Jacqueline, University of Central Florida
Abstract / Description: PCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system ...
Show morePCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system (AMTS) for the remediation and degradation of PCBs from concrete, brick, and granite affixed with PCB-laden caulking. The adsorption of PCBs onto the components of concrete and the feasibility of ethanol washing were also investigated.NMTS is a sorbent paste containing ethanol, acetic acid, and fillers that was developed at the University of Central Florida Environmental Chemistry Laboratory for the in situ remediation of PCBs. Combining NMTS with magnesium results in an activated treatment system used for reductive dechlorination of PCBs. NMTS was applied to laboratory-prepared concrete as well as field samples by direct contact as well as by a novel sock-type delivery. The remediation of PCBs from field samples using NMTS and AMTS resulted in a 33-98% reduction for concrete, a 65-70% reduction for brick, and an 89% reduction in PCB concentration for granite. The limit of NMTS for absorption of Aroclor 1254 was found to be roughly 22,000 mg Aroclor 1254 per kg of treatment system or greater. The activated treatment system resulted in a 94% or greater degradation of PCBs after seven days with the majority of degradation occurring in the first 24 hours. The adsorption of PCBs to individual concrete components (hydrated cement, sand, crushed limestone, and crushed granite) was found to follow the Freundlich isotherm model with greater adsorption to crushed limestone and crushed granite compared to hydrated cement and sand. Ethanol washing was shown to decrease the concentration of laboratory-prepared concrete by 68% and the concentration of PCBs in the ethanol wash were reduced by 77% via degradation with an activated magnesium system.
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Date Issued: 2013
Identifier: CFE0005197, ucf:50625
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005197

PCA (3)	+ -
PCB (3)	+ -
mPCA (3)	+ -
AKGA (2)	+ -
Chemometrics (2)	+ -

Degradation (2)	+ -
Hydrazine (2)	+ -
Remediation (2)	+ -
degradation (2)	+ -
environmental remediation (2)	+ -
forensic science (2)	+ -
magnesium (2)	+ -
monomethylhydrazine (2)	+ -
multivariate statistics (2)	+ -
polychlorinated biphenyl (2)	+ -
soil (2)	+ -
(Solid phase microextraction) SPME (1)	+ -
04/02/2018 (1)	+ -
3 (1)	+ -
5 (1)	+ -
6-trichloro-2-pyridinol (1)	+ -
AMTS (1)	+ -
Accelerated durability (1)	+ -
Activated carbon (1)	+ -
Agglomerative Hierarchical Cluster Analysis (1)	+ -
Ball-milled zero-valent magnesium (1)	+ -
Bayes' Theorem (1)	+ -
Bayesian Networks (1)	+ -
CdSe nanoparticles (1)	+ -
Ceramic nanofibers (1)	+ -

University of Central Florida (38)	+ -
Yestrebsky, Cherie (38)	+ -
Campiglia, Andres (15)	+ -
Clausen, Christian (14)	+ -
Sigman, Michael (11)	+ -

Randall, Andrew (9)	+ -
Duranceau, Steven (8)	+ -
Elsheimer, Seth (7)	+ -
Zou, Shengli (6)	+ -
Hampton, Michael (5)	+ -
Beazley, Melanie (4)	+ -
Bridge, Candice (4)	+ -
Frazer, Andrew (4)	+ -
Harper, James (4)	+ -
Legron-Rodriguez, Tamra (4)	+ -
Belfield, Kevin (3)	+ -
Chumbimuni Torres, Karin (3)	+ -
Ni, Liqiang (3)	+ -
Zhai, Lei (3)	+ -
Blair, Richard (2)	+ -
Griffin, Timothy (2)	+ -
Hernandez, Florencio (2)	+ -
Quinn, Jacqueline (2)	+ -
Rex, Matthew (2)	+ -
Schulte, Alfons (2)	+ -
Wang, Dingbao (2)	+ -
Almutairi, Adibah (1)	+ -
Appalaneni, Krishnaveni (1)	+ -
Calderon Flores, Jean (1)	+ -
Calimag, Korina Jesusa (1)	+ -

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