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Title: THE HYPERACCUMULATION OF ZINC IN SUNFLOWERS AND ITS EFFECT ON DISEASE RESISTANCE.
Creator: Seavey, Rayner J, Mason, Chase, University of Central Florida
Abstract / Description: Sunflowers are considered to be a part of a group of plants known as hyperaccumulators that share the ability to accumulate high amounts of heavy metals in the above ground organs, far in excess of the levels found in other species, often without suffering any phytotoxic effects. Quantifying the effects of zinc accumulation through the lens of the elemental defense hypothesis is essential for uncovering if there is a means to increase herbivore resistance in agricultural settings without the...
Show moreSunflowers are considered to be a part of a group of plants known as hyperaccumulators that share the ability to accumulate high amounts of heavy metals in the above ground organs, far in excess of the levels found in other species, often without suffering any phytotoxic effects. Quantifying the effects of zinc accumulation through the lens of the elemental defense hypothesis is essential for uncovering if there is a means to increase herbivore resistance in agricultural settings without the use of external interventions such as pesticides. A greenhouse study was conducted on four widely grown commercial cultivars of sunflower. Each cultivar was grown under multiple soil Zn concentrations ranging from 0 to 200 mg/kg of soil. Growth rate measurements were taken at evenly spaced intervals until maturity. Samples of leaves were taken from plants and tested for Zn concentration. A qualitative study using Vanessa cardui was conducted to observe the effects of zinc in the diet of caterpillars. Significant variation in the level of zinc accumulated in the leaves was observed as well as variation in overall biomass per treatment level. V. cardui experienced high rates of mortality at high zinc concentrations suggesting that further study may lead to significant evidence that Zinc accumulation is a form of herbivore resistance.
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Date Issued: 2019
Identifier: CFH2000491, ucf:45835
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000491

Title: THE EFFECTS OF ZINC NANOFERTILIZERS ON TOMATO PLANTS.
Creator: Pierre, Ketsira, Santra, Swadeshmukul, University of Central Florida
Abstract / Description: Farmers around the world aim to use soil with adequate nutrients to produce sufficient and quality crops to the world's ever-growing population. Unbalanced use of nutrients in the soil will lead to soil deficiency, which is usually seen in South and Southeast Asian countries. This soil deficiency is often due to loss of micronutrient(s) within the soil from farming practices. Micronutrient deficiency affects not only plant growth but human health. Plants grown in nutrient deficient soil...
Show moreFarmers around the world aim to use soil with adequate nutrients to produce sufficient and quality crops to the world's ever-growing population. Unbalanced use of nutrients in the soil will lead to soil deficiency, which is usually seen in South and Southeast Asian countries. This soil deficiency is often due to loss of micronutrient(s) within the soil from farming practices. Micronutrient deficiency affects not only plant growth but human health. Plants grown in nutrient deficient soil produce food with nutrient deficiencies, which affect people dependent on these foods for nutrients (Kathmandu, 2004). Nutrient deficient diseases and disorders like malnutrition are often seen in such cases. Current farming practices often involve leaching, mineralization, and bioconversion, which result in 50-70% loss of micronutrients. Smart practices from nanotechnology can lead conventional farming to more sustainable agriculture (Chhippa, 2016). This study aims to improve the dispersibility and uptake of zinc in plants different dual combination of ‘green' capping agents in zinc nanoparticles. The results of this study suggest tomato plants treated with urea coated with 3% Zn (w/w) using NAC-SAL ZnO showed a higher number of leaves and number of fruits set compared to controls.
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Date Issued: 2019
Identifier: CFH2000566, ucf:45665
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000566

Title: Coated Quantum Dots: Engineering of Surface Chemistry for Biomedical and Agricultural Applications.
Creator: Maxwell, Tyler, Santra, Swadeshmukul, Gesquiere, Andre, Harper, James, Zou, Shengli, Leon, Lorraine, University of Central Florida
Abstract / Description: Quantum dots (QDs) are crystalline nanoparticles made from semiconductor material with sizes ranging from 1 to 10 nm in diameter. QDs are attractive fluorophores for bioimaging and sensing due to their size-dependent optical properties, broad absorption bands, high extinction coefficients and superior photostability. The combination of imaging and drug delivery in a single particle can provide valuable information and improve the efficacy of existing treatments. This dissertation highlights...
Show moreQuantum dots (QDs) are crystalline nanoparticles made from semiconductor material with sizes ranging from 1 to 10 nm in diameter. QDs are attractive fluorophores for bioimaging and sensing due to their size-dependent optical properties, broad absorption bands, high extinction coefficients and superior photostability. The combination of imaging and drug delivery in a single particle can provide valuable information and improve the efficacy of existing treatments. This dissertation highlights the use of QDs for biomedical and agricultural applications. Chapter 1 of this dissertation presents a background of QDs and outlines the synthesis methods of producing and functionalizing QDs. A discussion of the advantages and limitations of each method for producing water-soluble QDs and the rationale for the proposed research is also presented. Chapter 2 describes an activatable QD design for tracking of drug delivery for cancer treatment. QDs synthesized by microemulsion (ME) were cross-linked in a one-step procedure. Enhanced binding affinity of the probe to cell lines overexpressing folate receptors was shown through fluorescence microscopy. However, this system is not practical for the large-scale synthesis due to its complexity and can not be translated for clinical development. Chapter 3 presents a sol-gel synthesis method for producing water-soluble QDs utilizing the thiol-based small molecule capping agent as the stabilizer as an alternative to ME technique. This method was designed to be a simple (one-step), cost-effective, and scalable for making both manganese doped CdS and ZnS QDs. QDs were synthesized through sol-gel method with a library of organic thiol coatings and characterized by size, surface charge, stability, and optical properties. These particles were compared to QDs produced from ME synthesis and were found to have similar properties. Chapter 4 reports the sol-gel QDs as slow-release antibiotic delivery system for application as agricultural bactericide. Utilizing electrostatic interactions, the QDs were shown to be capable of improving the leaf adhesion and slowing the rate of release of streptomycin. Chapter 5 presents a summary of the major findings of this research and discusses the future research directions.
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Date Issued: 2019
Identifier: CFE0007681, ucf:52476
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007681

Title: IMPACT OF ZINC ORTHOPHOSPHATE INHIBITOR ONDISTRIBUTION SYSTEM WATER QUALITY.
Creator: Guan, Xiaotao, Taylor, James, University of Central Florida
Abstract / Description: This dissertation consists of four papers concerning impacts of zinc orthophosphate (ZOP) inhibitor on iron, copper and lead release in a changing water quality environment. The mechanism of zinc orthophosphate corrosion inhibition in drinking water municipal and home distribution systems and the role of zinc were investigated. Fourteen pilot distribution systems (PDSs) which were identical and consisted of increments of PVC, lined cast iron, unlined cast iron and galvanized steel pipes were...
Show moreThis dissertation consists of four papers concerning impacts of zinc orthophosphate (ZOP) inhibitor on iron, copper and lead release in a changing water quality environment. The mechanism of zinc orthophosphate corrosion inhibition in drinking water municipal and home distribution systems and the role of zinc were investigated. Fourteen pilot distribution systems (PDSs) which were identical and consisted of increments of PVC, lined cast iron, unlined cast iron and galvanized steel pipes were used in this study. Changing quarterly blends of finished ground, surface and desalinated waters were fed into the pilot distribution systems over a one year period. Zinc orthophosphate inhibitor at three different doses was applied to three PDSs. Water quality and iron, copper and lead scale formation was monitored for the one year study duration. The first article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on surface characteristics of iron corrosion products in a changing water quality environment. Surface compositions of iron surface scales for iron and galvanized steel coupons incubated in different blended waters in the presence of ZOP inhibitor were investigated using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) / Energy Dispersive X-ray Spectroscopy (EDS). Based on surface characterization, predictive equilibrium models were developed to describe the controlling solid phase and mechanism of ZOP inhibition and the role of zinc for iron release. The second article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total iron release in a changing water quality environment. Development of empirical models as a function of water quality and ZOP inhibitor dose for total iron release and mass balances analysis for total zinc and total phosphorus data provided insight into the mechanism of ZOP corrosion inhibition regarding iron release in drinking water distribution systems. The third article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total copper release in a changing water quality environment. Empirical model development was undertaken for prediction of total copper release as a function of water quality and inhibitor dose. Thermodynamic models for dissolved copper based on surface characterization of scale that were generated on copper coupons exposed to ZOP inhibitor were also developed. Surface composition was determined by X-ray Photoelectron Spectroscopy (XPS). The fourth article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total lead release in a changing water quality environment. Surface characterization of lead scale on coupons exposed to ZOP inhibitor by X-ray Photoelectron Spectroscopy (XPS) was utilized to identify scale composition. Development of thermodynamic model for lead release based on surface analysis results provided insight into the mechanism of ZOP inhibition and the role of zinc.
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Date Issued: 2007
Identifier: CFE0001931, ucf:47453
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001931

Title: Precision Metrology of Laser Plasmas in the XUV Band.
Creator: Szilagyi, John, Richardson, Martin, Sundaram, Kalpathy, Abdolvand, Reza, Baudelet, Matthieu, Shivamoggi, Bhimsen, University of Central Florida
Abstract / Description: The XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 (-) 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor...
Show moreThe XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 (-) 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor manufacturing industry, medical surgery, micromachining, microscopy, and spectroscopy have begun to benefit from the short wavelengths and the high photon energies of this light. At present, the semiconductor chip industry is the primary reason for the investment in, and development of, XUV sources, optics, and detectors. The demand for high power EUV light sources at 13.5 nm wavelength is driven by the development of the next generation of semiconductor lithography tools. The development of these tools enables the continued reduction in size, and the increase in transistor density of semiconductor devices on a single chip. Further development and investigation of laser produced plasma EUV light sources is necessary to increase the average optical power and reliability. This will lead to an increase in the speed of EUV lithographic processes, which are necessary for future generations of advanced chip design, and high volume semiconductor manufacturing. Micromachining, lithography, and microscopy benefit from improvements in resolution due to the shorter wavelengths of light in the VUV band. In order to provide adequate illumination for these applications, sources are required which are brighter and have higher average power. Laser produced plasma (LPP) VUV light sources are used extensively for lithography and defect detection in semiconductor manufacturing. Reductions in the wavelength and increases in the average power will increase the rate and yield of chip manufacture, as well as reduce the costs of semiconductor manufacture.The work presented in this thesis, describes the development of two laser plasma source facilities in the Laser Plasma Laboratory at UCF, which were designed to investigate EUV and VUV laser plasma sources. The HP-EUV-Facility was developed to optimize and demonstrate a high power 13.5 nm EUV LPP source. This facility provides high resolution spectroscopy across 10.5 - 20 nm, and absolute energy measurement of 13.5 nm +/- 2% in 2? sr. The VUV-MS-Facility was developed to investigate VUV emission characteristics of laser plasmas of various target geometries and chemistries. This facility provides absolute calibrated emission spectra for the 124 - 250 nm wavelength range, in addition to, at wavelength plasma imaging. Calibrated emission spectra, in-band power, and conversion efficiency are presented in this work for gas targets of Argon, Krypton, and Xenon and solid targets of Silicon, Copper, Molybdenum, Indium, Tantalum, Tin, and Zinc, across the laser intensity range of 8.0x10^6 (-) 3.2x10^12 W/cm2.
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Date Issued: 2017
Identifier: CFE0006805, ucf:51793
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006805

Title: NANOCLUSTER THIN-FILMS FOR SENSOR APPLICATIONS.
Creator: Serritella, Joseph, Malocha, Donald, University of Central Florida
Abstract / Description: The ability to sense gas such as methane can provide an early warning system to protect human lives. High demand for the ability to sense the world around us has provided an extensive area of research for sensor technology. In particular, current sensor technology, specifically for methane, has provided sensors that require a heated environment to function. The majority of current methane sensors function at temperatures between 150[degrees]C and 450[degrees]C . This thesis will explore an...
Show moreThe ability to sense gas such as methane can provide an early warning system to protect human lives. High demand for the ability to sense the world around us has provided an extensive area of research for sensor technology. In particular, current sensor technology, specifically for methane, has provided sensors that require a heated environment to function. The majority of current methane sensors function at temperatures between 150[degrees]C and 450[degrees]C . This thesis will explore an approach to produce a room temperature methane sensor. This research will investigate techniques to create a sensor that is responsive to methane at 23[degrees]C. The approach will use the integration of a very thin film, which changes its resistive properties when methane gas is applied, deposited atop the surface of a piezoelectric substrate. An aluminum thin film interdigital transducer will launch a surface acoustic wave (SAW) that travels under the sensor's gas-sensitive resistive thin film. The SAW/resistive film interaction changes the SAW amplitude, phase and delay. For this work, three films, tin dioxide (SnO2), zinc oxide (ZnO) and palladium (Pd) [1, 2] will be studied. Gas detection will be shown when combining ZnO and Pd, and, observable change in SAW propagation loss is measured when methane gas is present at the film.
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Date Issued: 2015
Identifier: CFH0004832, ucf:45481
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004832

Title: DESIGN, SYNTHESIS, AND CHARACTERIZATION OF NOVEL HYDROPHILIC FLUORENE-BASED DERIVATIVES FOR BIOIMAGING APPLICATIONS.
Creator: Nguyen, Dao, Belfield, Kevin, University of Central Florida
Abstract / Description: In this work, hydrophilic fluorene-based derivatives that contain ethylene oxide substituents, have been synthesized and characterized for potential use as new fluorophores for bioimaging applications and for fluorescence sensing of heavy metals. Symmetrical and unsymmetrical fluorene derivatives based on structural types of acceptor-pi-acceptor, acceptor-pi-donor, and donor-pi-donor were characterized by TGA, UV-vis absorption, fluorescence emission, lifetime, anisotropy, and two-photon...
Show moreIn this work, hydrophilic fluorene-based derivatives that contain ethylene oxide substituents, have been synthesized and characterized for potential use as new fluorophores for bioimaging applications and for fluorescence sensing of heavy metals. Symmetrical and unsymmetrical fluorene derivatives based on structural types of acceptor-pi-acceptor, acceptor-pi-donor, and donor-pi-donor were characterized by TGA, UV-vis absorption, fluorescence emission, lifetime, anisotropy, and two-photon absorption (2PA) cross section. They were found to possess high thermal stability, high photostability, high fluorescence quantum yields, and generally large two-photon absorption cross sections, making them quite suitable for new probes in single-photon absorption and two-photon absorption fluorescence microscopy imaging. Novel hydrophilic fluorene derivatives were synthesized from fluorene in multiple steps employing the metal-catalyzed Heck coupling reaction, the Stille reaction, the Sonogashira reaction, the Ullmann condensation reaction, and "click" chemistry. To increase the hydrophilicity of the new compounds, ethylene oxide substituents were utilized for to impart water solubility. An alternative alkylation methodology using ethyleneoxy tosylates was introduced for the synthesis of ethylene oxide-containing fluorene derivatives. Several of these hydrophilic derivatives were incubated into various cell lines as new probes for both conventional and two-photon absorption fluorescence bioimaging. These compounds were biocompatible, exhibiting low cytotoxicity as determined by cell viability studies, and displayed colocalization for selected cellular organelles. In addition, hydrophilic bis(1,2,3-triazolyl)fluorene derivatives were found to exhibit sensitive fluorescence responses in the presence of certain heavy metal, and were selective for sensing zinc and mercury over other a number of other metal ions relevant to living cells or other biological environments. The UV-vis absorption and fluorescence emission spectra of the complexes exhibited a blue-shifted absorption and emission for selective metal chelation upon binding to zinc and mercury(II) ions, resulting in an approximately two-fold enhanced fluorescence response. Fluorescence titration studies revealed that the complexes of 1:2 and 1:3 ligand to metal formed with binding constant values of 108 and 1014 for zinc and mercury ions, respectively. Finally, preliminary experiments were performed to explore the possibility of employing select hydrophilic fluorene-based derivatives in the synthesis of hydrophilic fluorescent gold nanoparticles. Although results are very preliminary, the aim is to use such materials for other biomedical applications, such as surface enhanced scattering resonance and noninvasive photothermal therapy to diagnose and to treat cancers. Thus, this research had led to the discovery of alternative methodologies for synthesis of hydrophilic fluorene derivatives by alkylation with alkyl tosylates and synthesis of hydrophilic fluorescent molecule capped gold nanoparticles. Furthermore, several novel hydrophilic fluorene-based derivatives were synthesized and characterized for their linear and nonlinear photophysical properties, and are now available for further examination of their bioimaging and sensing applications.
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Date Issued: 2009
Identifier: CFE0002930, ucf:48002
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002930

Title: Fluorescence Lifetime Imaging and Spectroscopy Aided Tracking of ZnO and CdS:Mn/ZnS/ N-acetyl cysteine (NAC) Quantum Dots in Citrus Plants.
Creator: Washington, Torus, Gesquiere, Andre, Rajaraman, Swaminathan, Zhai, Lei, University of Central Florida
Abstract / Description: In this thesis, we present an efficacious way of tracking nanoparticle movement in plant tissue through the use of fluorescence lifetime imaging (FLIM) and spectroscopy as well as a review of nanoparticle uptake in plants and the proposed mechanisms governing them. Given the increasing number of nanomaterials in agriculture and society as a whole, proper imaging tools and proactive measures must be taken to track nanoparticle movement in plant tissues and create infrastructure and products to...
Show moreIn this thesis, we present an efficacious way of tracking nanoparticle movement in plant tissue through the use of fluorescence lifetime imaging (FLIM) and spectroscopy as well as a review of nanoparticle uptake in plants and the proposed mechanisms governing them. Given the increasing number of nanomaterials in agriculture and society as a whole, proper imaging tools and proactive measures must be taken to track nanoparticle movement in plant tissues and create infrastructure and products to keep things sustainable and safe. Herein we report a ZnO comparable nanoparticle(-) a CdS:Mn/ZnS/ N-acetyl cysteine (NAC) quantum dot(-) which boasts longer lifetimes and suitable fluorescent properties above ZnO to properly delineate from plant tissue fluorescence of chlorophyll and cinnamic acids. In addition to FLIM mapping, quantum dot localization in plant vascular tissue was clearly seen and confirmed via characteristic emission spectra and time correlated single photon counting decay curves (TCSPC). Most quantum dots were seen to reside in the xylem. Plant age and structure was seen to affect uptake. QD size likely restricted extensive translocation. Inhibitive effects of QDs were likely water and mechanical stress. We surmise that travel of the cadmium quantum dots up the leaf and branch plant tissues is likely most governed by diffusion as the quantum dots bound to the cell structures create a diffusion gradient which aids travel up the leaf.
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Date Issued: 2017
Identifier: CFE0006820, ucf:51772
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006820

Title: Plasticity of Central and Peripheral Nervous System: Effects of Oxygen-Glucose Deprivation (OGD), Chronic Intermittent Hypoxia (CIH) and hSOD1 Overexpression.
Creator: Chen, Jin, Cheng, Zixi, Naser, Saleh, Singla, Dinender, University of Central Florida
Abstract / Description: Transient receptor potential canonical 6 (TRPC6) channels are permeable to Na+ and Ca2+ and are widely expressed in the brain. In this study, we investigated the role of TRPC6 following ischemia/reperfusion (I/R) and oxygen-glucose deprivation (OGD). We found that TRPC6 expression was increased in wild type (WT) mice cortical neurons following I/R and in primary neurons with OGD, and that deletion of TRPC6 reduced the I/R-induced brain infarct in mice and the OGD- /neurotoxin-induced neuronal...
Show moreTransient receptor potential canonical 6 (TRPC6) channels are permeable to Na+ and Ca2+ and are widely expressed in the brain. In this study, we investigated the role of TRPC6 following ischemia/reperfusion (I/R) and oxygen-glucose deprivation (OGD). We found that TRPC6 expression was increased in wild type (WT) mice cortical neurons following I/R and in primary neurons with OGD, and that deletion of TRPC6 reduced the I/R-induced brain infarct in mice and the OGD- /neurotoxin-induced neuronal death. Using live-cell imaging to examine intracellular Ca2+ levels ([Ca2+]i), we found that OGD induced a significant higher increase in glutamate-evoked Ca2+ influx compared to untreated control and such an increase was reduced by TRPC6 deletion. Enhancement of TRPC6 expression using AdCMV-TRPC6-GFP infection in WT neurons increased [Ca2+]i in response to glutamate application compared to AdCMV-GFP control. Inhibition of N-methyl-d-aspartic acid receptor (NMDAR) with MK801 decreased TRPC6-dependent increase of [Ca2+]i, indicating that such a Ca2+ influx was NMDAR dependent. Furthermore, TRPC6-dependent Ca2+ influx was blunted by blockade of Na+ entry. Finally, OGD-enhanced Ca2+ influx was reduced, but not completely blocked, in the presence of voltage dependent Na+ channel blocker tetrodotoxin (TTX) and dl???amino?3?hydroxy?5?methyl?4?isoxazole propionic acid (AMPA) blocker CNQX. Altogether, we concluded that I/R-induced brain damage was, in part, due to upregulation of TRPC6 in cortical neurons. We postulate that overexpression of TRPC6 following I/R may induce neuronal death partially through TRPC6-dependent Na+ entry which activated NMDAR, thus leading to a damaging Ca2+ overload. These findings may provide a potential target for future intervention in stroke-induced brain damage. Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder that is associated with many cardiovascular complications, such as autonomic dysfunctions, stroke and heart failure. Chronic intermittent hypoxia (CIH) is a prominent feature of OSA. In CIH exposed rodents (a model for OSA), CIH induces the similar cardiovascular complications as seen in OSA patients. In particular, OSA impairs baroreflex control of the heart rate (HR), which is used as an independent indicator for heart failure. Since the baroreflex control arc includes the aortic depressor nerve (ADN), vagal efferent and central components, we hypothesize that CIH induces dysfunctions of all three components. Since mice can be genetically manipulated, an understanding of the effects of CIH on multiple neural components in the baroreflex arc in wild type mice may lead to a future study of treatments. In this study, we have examined the effects of CIH on baroreceptor afferent, central and vagal efferent components of the baroreflex circuitry in normal wild type C57BL/6J mice. Mice (4-5 months) were exposed to room air (RA) or CIH for 35-50 days and were then anesthetized with isoflurane, ventilated and catheterized for measurement of mean arterial blood pressure (MAP) and HR. Baroreceptor function was characterized by measuring percent changes of integrated ADN activity (Int ADNA) relative to the baseline value in response to the vasodilator sodium nitroprusside and the vasoconstrictor phenylephrine-induced changes in MAP. Data were fitted to a sigmoid logistic function curve. HR responses to electrical stimulation of the left ADN and the right vagus nerve were assessed under anesthesia. Compared with RA controls, CIH significantly increased maximum baroreceptor gain or maximum slope, maximum Int ADNA, and Int ADNA range (maximum-minimum Int ADNA). In addition, CIH maintained the maximum amplitude of the bradycardic response to vagal efferent stimulation. In contrast, CIH significantly reduced the maximum amplitude of bradycardic response to left ADN stimulation. Thus, CIH decreased central mediation of the baroreflex, but augmented the baroreceptor afferent function and maintained vagal efferent control of HR in mice. Excessive reactive oxygen species (ROS) (such as the superoxide radical) is commonly associated with cardiac autonomic dysfunctions. Though superoxide dismutase 1 (SOD1) overexpression may protect against ROS damage to the autonomic nervous system, superoxide radical reduction may change normal physiological functions. Previously, we demonstrated that human SOD1 (hSOD1) overexpression did not change baroreflex bradycardia and tachycardia, but increased aortic depressor nerve activity (ADNA) in responses to arterial pressure changes in C57B6SJL-Tg (SOD1)2 Gur/J mice. Since the barorelfex arc includes afferent, central and efferent components, the objective of this study was to determine whether hSOD1 overexpression alters the central and vagal efferent mediation of the heart rate (HR) responses. Our data indicate that SOD1 overexpression decreased HR responses to vagal efferent nerve stimulations but did not change HR responses to aortic nerve stimulation. Along with the previous study, we suggest that SOD1 overexpression preserves the normal baroreflex function but may alter the functions of aortic depressor nerve, vagal efferent and central components differently. While SOD1 overexpression likely enhanced aortic depressor nerve function and central mediation of bradycardia, it decreased vagal efferent control of HR. Currently, we are using the hSOD1 overexpressing mouse model to determine whether hSOD1 overexpression can preserve normal afferent, efferent, and central components of the baroreflex arc in the CIH model of sleep apnea.
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Date Issued: 2017
Identifier: CFE0006576, ucf:51334
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006576

Title: Modeling and Spray Pyrolysis Processing of Mixed Metal Oxide Nano-Composite Gas Sensor Films.
Creator: Khatami, Seyed Mohammad Navid, Ilegbusi, Olusegun, Deng, Weiwei, Kassab, Alain, Coffey, Kevin, Divo, Eduardo, University of Central Florida
Abstract / Description: The role of sensor technology is obvious in improvement and optimization of many industrial processes. The sensor films, which are considered the core of chemical sensors, have the capability to detect the presence and concentration of a specific chemical substance. Such sensor films achieve selectivity by detecting the interaction of the specific chemical substance with the sensor material through selective binding, adsorption and permeation of analyte. This research focuses on development...
Show moreThe role of sensor technology is obvious in improvement and optimization of many industrial processes. The sensor films, which are considered the core of chemical sensors, have the capability to detect the presence and concentration of a specific chemical substance. Such sensor films achieve selectivity by detecting the interaction of the specific chemical substance with the sensor material through selective binding, adsorption and permeation of analyte. This research focuses on development and verification of a comprehensive mathematical model of mixed metal oxide thin film growth using spray pyrolysis technique (SPT). An experimental setup is used to synthesize mixed metal oxide films on a heated substrate. The films are analyzed using a variety of characterization tools. The results are used to validate the mathematical model. There are three main stages to achieve this goal: 1) A Lagrangian-Eulerian method is applied to develop a CFD model of atomizing multi-component solution. The model predicts droplet characteristics in flight, such as spatial distribution of droplet size and concentration. 2) Upon reaching the droplets on the substrate, a mathematical model of multi-phase transport and chemical reaction phenomena in a single droplet is developed and used to predict the deposition of thin film. The various stages of droplet morphology associated with surface energy and evaporation are predicted. 3) The processed films are characterized for morphology and chemical composition (SEM, XPS) and the data are used to validate the models as well as investigate the influence of process parameters on the structural characteristics of mixed metal oxide films. The structural characteristics are investigated of nano structured thin films comprising of ZnO, SnO2, ZnO+In2O3 and SnO2+In2O3 composites. The model adequately predicts the size distribution and film thickness when the nanocrystals are well-structured at the controlled temperature and concentration.
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Date Issued: 2014
Identifier: CFE0005817, ucf:50048
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005817

Title: Interdiffusion and Impurity Diffusion in Magnesium Solid Solutions.
Creator: Kammerer, Catherine, Sohn, Yongho, Coffey, Kevin, Suryanarayana, Challapalli, Gordon, Ali, University of Central Florida
Abstract / Description: Magnesium, being lightweight, offers potential to be developed into extensive structural applications. The transportation segment has particular interest in Mg and Mg alloy for applications where reduced vehicle weight is proportional to increased fuel efficiency. Aluminum and zinc are two of the most common alloying elements in commercial Mg alloys. They improve the physical properties of Mg through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the...
Show moreMagnesium, being lightweight, offers potential to be developed into extensive structural applications. The transportation segment has particular interest in Mg and Mg alloy for applications where reduced vehicle weight is proportional to increased fuel efficiency. Aluminum and zinc are two of the most common alloying elements in commercial Mg alloys. They improve the physical properties of Mg through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the kinetics of and microstructural development during solidification and heat treatment. However, there is limited diffusion data available for Mg and Mg alloys. In particular, because Al is mono-isotopic, tracer diffusion data is not available. Interdiffusion of Mg solid solution with Zn also does not exist in literature. The diffusional interaction of Al and Zn in Mg solid solution at temperatures ranging from 623 (-) 723K was examined using solid-to-solid diffusion couple method. The objective of this thesis is two-fold: first, is the examination of interdiffusion in the Mg solid solution phase of the binary Mg-Al and Mg-Zn systems; second, is to explore non-conventional analytical methods to determine impurity diffusion coefficients. The quality of diffusion bonding was examined by optical microscopy and scanning electron microscopy with X-ray energy dispersive spectroscopy, and concentration profiles were determined using electron probe microanalysis with pure standards and ZAF matrix correction. Analytical methods of concentration profiles based on Boltzmann-Matano analysis for binary alloys are presented along with compositional dependent interdiffusion coefficients. As the concentration of Al or Zn approaches the dilute ends, an analytical approach based on the Hall method was employed to estimate the impurity diffusion coefficients.Zinc was observed to diffuse faster than Al, and in fact, the impurity diffusion coefficient of Al was smaller than the self-diffusion coefficient of Mg. In the Mg solid solution with Al, interdiffusion coefficients increased by an order of magnitude with an increase in Al concentration. Activation energy and pre-exponential factor for the average effective interdiffusion coefficient in Mg solid solution with Al was determined to be 186.8 KJ/mole and 7.69 x 10-1 m^2/sec. On the other hand, in the Mg solid solution with Zn, interdiffusion coefficients did not vary significantly as a function of Zn concentration. Activation energy and pre-exponential factor for the average effective interdiffusion coefficient in Mg solid solution with Zn was determined to be 129.5 KJ/mole and 2.67 x 10-4 m^2/sec. Impurity diffusion coefficients of Al in Mg was determined to have activation energy and pre-exponential factor of 144.1 KJ/mole and 1.61 x 10-4 m^2/sec. Impurity diffusion coefficients of Zn in Mg was determined to have activation energy and pre-exponential factor of 109.8 KJ/mole and 1.03 x 10-5 m^2/sec. Temperature and composition-dependence of interdiffusion coefficients and impurity diffusion coefficients are examined with respect to reported values in literature, thermodynamic factor, ?, diffusion mechanisms in hexagonal close packed structure, and experimental uncertainty.
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Date Issued: 2013
Identifier: CFE0004699, ucf:49851
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004699

Title: THE APPLICATION OF TWO-PHOTON ABSORBING PROBES IN LYSOSOMAL, ZINC ION SENSING AND FOLATE RECEPTOR-TARGETED BIOIMAGING.
Creator: WANG, XUHUA, Belfield, Kevin D., University of Central Florida
Abstract / Description: Two-photon fluorescence microscopy (2PFM) has become a powerful technique for bioimaging in non-invasive cancer diagnosis and also investigating the mechanization and original of a variety of diseases by tracking various biological processes. Because the fluorescence emission by two photon absorbing (2PA) is directly proportional to the square of the intensity of excitation light, this intrinsic property of 2PA provides 2PFM great advantages over traditional one-photon fluorescence microscopy...
Show moreTwo-photon fluorescence microscopy (2PFM) has become a powerful technique for bioimaging in non-invasive cancer diagnosis and also investigating the mechanization and original of a variety of diseases by tracking various biological processes. Because the fluorescence emission by two photon absorbing (2PA) is directly proportional to the square of the intensity of excitation light, this intrinsic property of 2PA provides 2PFM great advantages over traditional one-photon fluorescence microscopy (1PFM), including high 3D spatial localization, less photodamage and interference from biological tissue because of using longer wavelength excitation (700-1300 nm). However, most 2PA probes are hydrophobic and their photostabilities are questionable, severely limiting their biological and medical applications. In addition, probes with significant specificity for certain organelles for tracking cellular processes or metal ions for monitoring neural transmission are somewhat rare. Moreover, it is also very significant to deliver the probes to specific disease sites for early cancer diagnosis. In order to increase the water solubility of probes, polyethylene glycol (PEG) was introduced to a fluorene-based 2PA probe LT1 for lysosomal 2PFM cell imaging. The 2PFM bioimaging application of the novel two-photon absorbing fluorene derivative LT1, selective for the lysosomes of HCT 116 cancer cells is described in Chapter II. Linear and nonlinear photophysical and photochemical properties of the probe were investigated to evaluate the potential of the probe for 2PFM lysosomal imaging. After the investigation of the cytotoxicity of this new probe, colocalization studies of the probe with commercial lysosomal probe Lysotracker Red in HCT 116 cells were conducted. A high colocalization coefficient (0.96) was achieved and demonstrated the specific localization of the probe in lysosomes. A figure of merit, FM, was introduced by which all fluorescent probes for 2PFM can be compared. LT1 was demonstrated to have a number of properties that far exceed those of commercial lysotracker probes, including much higher 2PA cross sections, good fluorescence quantum yield, and, importantly, high photostability, all resulting in a superior figure of merit. Consequently, 2PFM was used to demonstrate lysosomal tracking with LT1. In addition to lysosomes, it is also very significant to investigate the physiological roles of free metal ions in biological processes, especially Zn2+, because Zn2+ normally serves either as the catalytic elements in enzymatic activity centers or as structural elements in enzymes and transcription factors. However, biocompatible and effective Zn2+ probes for 2PFM bioimaging are infrequent. In Chapter III, 2PFM bioimaging with a hydrophilic 2PA Zn2+ sensing fluorescent probe, bis(1,2,3-triazolyl)fluorene derivative, is described. 2PFM bioimaging of the probe in living HeLa cancer cells was demonstrated. The results revealed a significant fluorescence increase upon introduction of Zn2+ into the cancer cells, and a reversible Zn2+ binding to the probe was also demonstrated, providing a robust probe for two-photon fluorescence zinc ion sensing. Early cancer diagnosis is another critical application for 2PFM, but there are still huge challenges for this new technique in clinical areas. Most 2PA probes with large two-photon absorbing cross sections and fluorescence quantum efficiency are synthetically more accessible in hydrophobic forms. In order to increase the efficiency of the probes and minimize the effect of the probe on the human body, delivery of the probe specifically to cancer sites is desired. The synthesis and characterization of narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, are reported in Chapter IV. The surface of the SiNPs was functionalized with folic acid to specifically deliver the probe to folate receptor (FR) over-expressing HeLa cells, making these folate 2PA dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing HeLa cells demonstrated specific cellular uptake of the functionalized nanoparticles. However, when the concentration of the dye in SiNPs increased for higher signal output, the fluorescence quantum efficiency of a probe normally decreases because of self-quenching. In Chapter V, a near-infrared (NIR) emitting probe is reported to overcome this limitation through both aggregate-enhanced fluorescence emission and aggregate enhanced two-photon absorption. The dye was encapsulated in SiNPs and the surface of the nanoparticles was functionalized with PEG followed by a folic acid derivative to specifically target folate receptors. NIR emission is important for deep tissue imaging. In vitro studies using HeLa cells that upregulate folate receptors indicated specific cellular uptake of the folic acid functionalized SiNP nanoprobe. Meanwhile, the probe was also investigated for live animal imaging by employing mice bearing HeLa tumors for in vivo studies. Ex vivo 2PFM tumor imaging was then conducted to achieve high quality 3D thick tissue tumor images.
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Date Issued: 2011
Identifier: CFE0003640, ucf:48891
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003640

Title: The Influence of Alloying Additions on Diffusion and Strengthening of Magnesium.
Creator: Kammerer, Catherine, Sohn, Yongho, Coffey, Kevin, Challapalli, Suryanarayana, Gordon, Ali, University of Central Florida
Abstract / Description: Magnesium alloys are being developed as advanced materials for structural applications where reduced weight is a primary motivator. Alloying can enhance the properties of magnesium without significantly affecting its density. Essential to alloy development, inclusive of processing parameters, is knowledge of thermodynamic, kinetic, and mechanical behavior of the alloy and its constituents. Appreciable progress has been made through conventional development processes, but to accelerate...
Show moreMagnesium alloys are being developed as advanced materials for structural applications where reduced weight is a primary motivator. Alloying can enhance the properties of magnesium without significantly affecting its density. Essential to alloy development, inclusive of processing parameters, is knowledge of thermodynamic, kinetic, and mechanical behavior of the alloy and its constituents. Appreciable progress has been made through conventional development processes, but to accelerate development of suitable wrought Mg alloys, an integrated Materials Genomic approach must be taken where thermodynamics and diffusion kinetic parameters form the basis of alloy design, process development, and properties-driven applications.The objective of this research effort is twofold: first, to codify the relationship between diffusion behavior, crystal structure, and mechanical properties; second, to provide fundamental data for the purpose of wrought Mg alloy development. Together, the principal deliverable of this work is an advanced understanding of Mg systems. To that end, the objective is accomplished through an aggregate of studies. The solid-to-solid diffusion bonding technique is used to fabricate combinatorial samples of Mg-Al-Zn ternary and Mg-Al, Mg-Zn, Mg-Y, Mg-Gd, and Mg-Nd binary systems. The combinatorial samples are subjected to structural and compositional characterization via Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy, Electron Probe Microanalysis, and analytical Transmission Electron Microscopy. Interdiffusion in binary Mg systems is determined by Sauer-Freise and Boltzmann-Matano methods. Kirkaldy's extension of the Boltzmann-Matano method, on the basis of Onsager's formalism, is employed to quantify the main- and cross-interdiffusion coefficients in ternary Mg solid solutions. Impurity diffusion coefficients are determined by way of the Hall method. The intermetallic compounds and solid solutions formed during diffusion bonding of the combinatorial samples are subjected to nanoindentation tests, and the nominal and compositionally dependent mechanical properties are extracted by the Oliver-Pharr method.In addition to bolstering the scantly available experimental data and first-principles computations, this work delivers several original contributions to the state of Mg alloy knowledge. The influence of Zn concentration on Al impurity diffusion in binary Mg(Zn) solid solution is quantified to impact both the pre-exponential factor and activation energy. The main- and cross-interdiffusion coefficients in the ternary Mg solid solution of Mg-Al-Zn are reported wherein the interdiffusion of Zn is shown to strongly influence the interdiffusion of Mg and Al. A critical examination of rare earth element additions to Mg is reported, and a new phase in thermodynamic equilibrium with Mg-solid solution is identified in the Mg-Gd binary system. It is also demonstrated that Mg atoms move faster than Y atoms. For the first time the mechanical properties of intermetallic compounds in several binary Mg systems are quantified in terms of hardness and elastic modulus, and the influence of solute concentration on solid solution strengthening in binary Mg alloys is reported. The most significant and efficient solid solution strengthening is achieved by alloying Mg with Gd. The Mg-Nd and Mg-Gd intermetallic compounds exhibited better room temperature creep resistance than intermetallic compounds of Mg-Al. The correlation between the concentration dependence of mechanical properties and atomic diffusion is deliberated in terms of electronic nature of the atomic structure.
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Date Issued: 2015
Identifier: CFE0005815, ucf:50043
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005815

Zinc (3)	+ -
Zinc Oxide (2)	+ -
zinc (2)	+ -
1 (1)	+ -
2 (1)	+ -

3-triazole derivative (1)	+ -
Acoustic (1)	+ -
Aerosol (1)	+ -
Al (1)	+ -
Aluminum (1)	+ -
Boltzmann-Matano (1)	+ -
Cadmium uptake (1)	+ -
Characterization (1)	+ -
Chemical spray pyrolysis (1)	+ -
Chronic Intermittent Hypoxia (CIH) (1)	+ -
Citrus (Citrus aurantium (1)	+ -
Citrus (Citrus sinesis.) (1)	+ -
Combinatorial Sample (1)	+ -
Computational fluid dynamics (1)	+ -
Corrosion Control (1)	+ -
Corrosion Inhibitor (1)	+ -
Diffusion (1)	+ -
Drinking Water Distribution System (1)	+ -
Drinking Water Quality (1)	+ -
EUV (1)	+ -
EUVL (1)	+ -
Film growth (1)	+ -
Film processing (1)	+ -
Fluorescence Lifetime Imaging (1)	+ -
Fluorescence bioimaging probe (1)	+ -

ETD Collection (10)	+ -
Honors Collection (3)	+ -

University of Central Florida (13)	+ -
Coffey, Kevin (3)	+ -
Gesquiere, Andre (2)	+ -
Gordon, Ali (2)	+ -
Kammerer, Catherine (2)	+ -

Santra, Swadeshmukul (2)	+ -
Sohn, Yongho (2)	+ -
Abdolvand, Reza (1)	+ -
Baudelet, Matthieu (1)	+ -
Belfield, Kevin (1)	+ -
Belfield, Kevin D. (1)	+ -
Challapalli, Suryanarayana (1)	+ -
Chen, Jin (1)	+ -
Cheng, Zixi (1)	+ -
Deng, Weiwei (1)	+ -
Divo, Eduardo (1)	+ -
Guan, Xiaotao (1)	+ -
Harper, James (1)	+ -
Ilegbusi, Olusegun (1)	+ -
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Khatami, Seyed Mohammad Navid (1)	+ -
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