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(1 - 20 of 20)
- Title
- PROCESSING AND STUDY OF CARBON NANOTUBE / POLYMER NANOCOMPOSITES AND POLYMER ELECTROLYTE MATERIALS.
- Creator
-
Harish, Muthuraman, Huo, Qun, University of Central Florida
- Abstract / Description
-
The first part of the study deals with the preparation of carbon nanotube/polymer nanocomposite materials. The dispersion of multi-walled carbon nanotubes (MWNTs) using trifluoroacetic acid (TFA) as a co-solvent and its subsequent use in polymer nanocomposite fabrication is reported. The use of carbon nanotube/ polymer nanocomposite system for the fabrication of organic solar cells is also studied. TFA is a strong but volatile acid which is miscible with many commonly used organic solvents....
Show moreThe first part of the study deals with the preparation of carbon nanotube/polymer nanocomposite materials. The dispersion of multi-walled carbon nanotubes (MWNTs) using trifluoroacetic acid (TFA) as a co-solvent and its subsequent use in polymer nanocomposite fabrication is reported. The use of carbon nanotube/ polymer nanocomposite system for the fabrication of organic solar cells is also studied. TFA is a strong but volatile acid which is miscible with many commonly used organic solvents. Our study demonstrates that MWNTs can be effectively purified and readily dispersed in a range of organic solvents including dimethyl formamide (DMF), tetrahydrofuran (THF), and dichloromethane when mixed with 10 vol% trifluoroacetic acid (TFA). X-ray photoelectron spectroscopic analysis revealed that the chemical structure of the TFA-treated MWNTs remained intact without oxidation. The dispersed carbon nanotubes in TFA/THF solution were mixed with poly(methyl methacrylate) (PMMA) to fabricate polymer nanocomposites. A good dispersion of nanotubes in solution and in polymer matrices was observed and confirmed by SEM and optical microscopy study. Low percolation thresholds of electrical conductivity were observed from the fabricated MWNT/PMMA composite films. A carbon nanotube/ polymer nanocomposites system was also used for the fabrication of organic solar cells. A blend of single-wall carbon nanotubes (SWNTs) and poly3-hexylthiophene (P3HT) was used as the active layer in the device. The device characteristics showed that the fabrication of the solar cells was successful without any shorts in the circuit. The second part of the study deals with the preparation and characterization of electrode and electrolyte materials for lithium ion batteries. A system of lithium trifluoroacetate/ PMMA was used for its study as the electrolyte in lithium battery. A variety of different processing conditions were used to prepare the polymer electrolyte system. The conductivity of the electrolyte plays a critical role in the high power output of a battery. A high power output requires fast transport of lithium ions for which the conductivity of the electrolyte must be at least 3 x 10^-4 S/cm. Electrochemical Impedance Spectroscopy (EIS) was used to determine the conductivity of the polymer electrolyte films. Among the different processing conditions used to prepare the polymer electrolyte material, wet films of PMMA/salt system prepared by using 10vol% of TFA in THF showed the best results. At about 70wt% loading of the salt in the polymer, the conductivity obtained was about 1.1 x 10^-2 S/cm. Recently, the use of vanadium oxide material as intercalation host for lithium has gained widespread attention. Sol-gel derived vanadium oxide films were prepared and its use as a cathode material for lithium ion battery was studied. The application of carbon nanotubes in lithium ion battery was explored. A carbon nanotube /block copolymer (P3HT-b-PS) composite was prepared and its potential as an anode material was evaluated.
Show less - Date Issued
- 2007
- Identifier
- CFE0001941, ucf:47436
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001941
- Title
- GOLD NANOPARTICLES: SYNTHESIS, PROPERTY STUDY AND APPLCICATIONS FORBIOMOLECULAR DETECTION AND PHOTOTHERMAL THERAPY.
- Creator
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liu, xiong, Huo, Qun, University of Central Florida
- Abstract / Description
-
This dissertation presents a systematic study on gold nanoparticles: from their chemical synthesis, modification of surface functionalities, optical properties studies with emphasis on the absorption and scattering properties, to applications of gold nanoparticles in biomolecular detection, imaging and photothermal therapy. In chapter 2, we studied the kinetics of gold nanoparticle growth under Brust-Shiffrin reaction conditions. In chapter 3, we further examined the reaction mechanism and...
Show moreThis dissertation presents a systematic study on gold nanoparticles: from their chemical synthesis, modification of surface functionalities, optical properties studies with emphasis on the absorption and scattering properties, to applications of gold nanoparticles in biomolecular detection, imaging and photothermal therapy. In chapter 2, we studied the kinetics of gold nanoparticle growth under Brust-Shiffrin reaction conditions. In chapter 3, we further examined the reaction mechanism and growth kinetics of gold nanoparticles using oleylamine as both a reducing reagent and particle growth passivation ligand. From these two projects, important understanding was revealed on gold nanoparticle formation and growth mechanism. Chapter 4 describes the synthesis of a monofunctional gold nanoparticle through a solid phase place exchange reaction. From Chapter 5, we moved to the optical property study of gold nanoparticles, particularly the absorption and scattering phenomenon. In this work a systematic analysis on the extinction coefficient of gold nanoparticles was performed, providing meaningful references for applications based on optical absorption properties of gold nanoparticles. In Chapter 6 and Chapter 7, we developed a one-step homogeneous immunoassay for protein detection and analysis based on the strong light scattering of gold nanoparticles and dynamic light scattering detection technique. In Chapter 8, we further improved the stability of gold nanoparticle bioconjugates using a poly(ethylene glycol)-coated gold nanoparticles and further tested this nanoparticle in the one-step homogeneous immunoassay. Finally in Chapter 9, we demonstrated the application of gold nanoparticles for in vitro bioimaging and photothermal therapy of a lung cancer cell. In summary, this dissertation presents a comprehensive study on the synthesis, surface modification, property study of gold nanoparticles and their applications in biomolecular imaging and analysis.
Show less - Date Issued
- 2009
- Identifier
- CFE0002874, ucf:48020
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002874
- Title
- DEVELOPMENT AND APPLICATION STUDY OF NANOSCALE THIN FILM MATERIALS AND POLYMER NANOCOMPOSITES.
- Creator
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Chen, Hui, Huo, Qun, University of Central Florida
- Abstract / Description
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This dissertation demonstrated that the manipulation of substances at the molecular or nanometer level can lead to the discovery and development of new materials with interesting properties and important applications. Chapter 1 describes the development of a nanoscale molecular thin film material for corrosion protection. By using a self-assembled monolayer film with a thickness of only about 1 nanometer as a linkage, a covalent bonding was achieved between a polyurethane top coating and an...
Show moreThis dissertation demonstrated that the manipulation of substances at the molecular or nanometer level can lead to the discovery and development of new materials with interesting properties and important applications. Chapter 1 describes the development of a nanoscale molecular thin film material for corrosion protection. By using a self-assembled monolayer film with a thickness of only about 1 nanometer as a linkage, a covalent bonding was achieved between a polyurethane top coating and an aluminum alloy substrate. This covalent bonding between polymer top coating and the aluminum alloy substrate significantly improved the corrosion resistance of the substrate. Chapter 2 and Chapter 3 describe the development of a gold nanoparticle-polymer composite material in different forms with a number of applications. Gold nanoparticles are among one of the most extensively studied nanomaterials. When the size of gold is shrunk to the nanometer scale, many interesting and new physical properties start to appear from gold nanoparticles. The optical properties of gold nanoparticles, particularly the surface plasmon resonance absorption, have been investigated in this dissertation for the development of multifunctional nanocomposite materials. Chapter 2 presents the preparation of a gold nanoparticle/poly(methyl methacrylate) (PMMA) nanocomposite film and the application of such films for microstructure fabrication using a direct laser writing technique. Gold nanoparticles are excellent photon-thermal energy converters due to their large absorption cross section at the surface plasmon resonance region. Upon laser irradiation of the nanocomposite film, the thermal energy converted from the absorbed photon energy by gold nanopaticles induced a complete decomposition of PMMA, leading to the formation of various microstructures on the nanocomposite films. Chapter 3 reports the further development of a nanoparticle/polymer composite nanofiber material fabricated through an electrospinning process. The matrix of the nanofiber is made of two polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH). Three methods were developed to incorporate gold nanoparticles into the polymer matrix. The composite nanofiber materials developed in this study demonstrate multifunctional properties, including good electrical conductivity, photothermal response, and surface-enhanced IR absorption. This material may be used for many important applications including catalysis, chemical and biological sensors, and scaffold materials for tissue engineering. In Chapter 4, another most important nanomaterial, carbon naotubes (CNTs), were introduced as fillers to prepare polymer nanocomposites. A dispersion method for multi-walled carbon nanotubes (MWCNTs) using a conjugated conducting polymer, poly(3-hexylthiophene) (P3HT) as the third component and trifluoroacetic acid (TFA) as a co-solvent was developed. Due to the excellent dispersion of carbon nanotubes in PMMA and enhanced conductivity of the nanocomposites by the conjugated conducting polymers, the prepared composite materials has an extremely low percolation threshold of less than 0.006 wt% of MWCNT content. The potential use of MWCNT/conducting polymer composites for energy storage applications such as suppercapacitors was further investigated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and charging-discharging cycles. Compared to pure carbon nanotubes, the nanocomposite materials have significantly improved properties and are promising for supercapacitor applications.
Show less - Date Issued
- 2008
- Identifier
- CFE0002265, ucf:47825
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002265
- Title
- SURFACE ENGINEERING OF GOLD NANOPARTICLES AND THEIR APPLICATIONS.
- Creator
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Dai, Qiu, Huo, Qun, University of Central Florida
- Abstract / Description
-
Gold nanoparticles (AuNPs) with their unique sizes, shapes, and properties have generated much enthusiasm over the last two decades, and have been explored for many potential applications. The successful application of AuNPs depends critically on the ability to modify and functionalize their surface to provide stability, compatibility, and special chemical functionality. This dissertation is aimed at exploring the chemical synthesis and surface modification of AuNPs with the effort to (1)...
Show moreGold nanoparticles (AuNPs) with their unique sizes, shapes, and properties have generated much enthusiasm over the last two decades, and have been explored for many potential applications. The successful application of AuNPs depends critically on the ability to modify and functionalize their surface to provide stability, compatibility, and special chemical functionality. This dissertation is aimed at exploring the chemical synthesis and surface modification of AuNPs with the effort to (1) control the number of functional groups on the particle surface, and to (2) increase the colloidal stability at the physiological conditions. To control the functionality on the particle surface, a solid phase place exchange reaction strategy was developed to synthesize the 2 nm AuNPs with a single carboxylic acid group attached on the particle surface. Such monofunctional AuNPs can be treated and used as molecular nanobuilding blocks to form more complex nanomaterials with controllable structures. A "necklace"-like AuNP/polymer assembly was obtained by conjugating covalently the monofunctional AuNPs with polylysine template, and exhibited an enhanced optical limiting property due to strong electromagnetic interaction between the nanoparticles in close proximity. To improve the colloidal stability in the psychological condition, biocompatible polymers, polyacrylic acid (PAA), and polyethylene glycol (PEG) were used to surface modify the 30 nm citrate-stabilized AuNPs. These polymer-modified AuNPs are able to disperse individually in the high ionic strength solution, and offer as the promising optical probes for bioassay applications. The Prostate specific antigen (PSA) and target DNA can be detected in the low pM range by taking advantages of the large scattering cross section of AuNPs and the high sensitivity of dynamic light scattering (DLS) measurement. In addition to the large scattering cross section, AuNPs can absorb strongly the photon energy at the surface plasmon resonance wavelength and then transform efficiently to the heat energy. The efficient photon-thermal energy conversion property of AuNPs has been used to thermal ablate the Aβ peptide aggregates under laser irradiation toward Alzheimer's disease therapy.
Show less - Date Issued
- 2008
- Identifier
- CFE0002395, ucf:47767
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002395
- Title
- Fabrication of Polyelectrolyte Nanoparticles Through Hydrophobic Interaction.
- Creator
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Catarata, Ruginn Porce, Zhai, Lei, Kang, Ellen, Huo, Qun, University of Central Florida
- Abstract / Description
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Anticancer drugs like gemcitabine (GEM) are used to treat cancers such as, pancreatic ductal adenocarcinoma (PDAC). However, the use of free gemcitabine yields challenges including cytotoxicity to healthy cells and poor circulation time. By encapsulating GEM in nanoparticles these challenges can be overcome. In this study poly(acrylic acid) (PAA)-GEM nanoparticles are fabricated by coupling GEM onto PAA. The particle formation is driven by the hydrophobic interaction of GEM, which collects in...
Show moreAnticancer drugs like gemcitabine (GEM) are used to treat cancers such as, pancreatic ductal adenocarcinoma (PDAC). However, the use of free gemcitabine yields challenges including cytotoxicity to healthy cells and poor circulation time. By encapsulating GEM in nanoparticles these challenges can be overcome. In this study poly(acrylic acid) (PAA)-GEM nanoparticles are fabricated by coupling GEM onto PAA. The particle formation is driven by the hydrophobic interaction of GEM, which collects in the core of the nanoparticle, forming a PAA shell. The nanoparticles were optimized by studying the PAA/GEM ratio and pH during fabrication. Characteristics of the nanoparticles including size, morphology and surface charge were investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential measurements. Conditions such as ionic stability and pH stability were optimized to achieve high drug loading efficiency. Cell uptake and cytotoxicity studies were used to determine the efficiency of the nanoparticles as drug delivery vehicle.
Show less - Date Issued
- 2019
- Identifier
- CFE0007791, ucf:52364
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007791
- Title
- High Power Continuous Wave Quantum Cascade Lasers With Increased Ridge Width.
- Creator
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Todi, Ankesh, Lyakh, Arkadiy, Huo, Qun, Tetard, Laurene, University of Central Florida
- Abstract / Description
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Quantum Cascade Lasers have recently gained considerable attention for their capability to emit infrared radiation in a broad infrared spectral region, very compact dimensions, and high optical power/efficiency. Increasing continuous wave optical power is one of the main research directions in the field. A straightforward approach to increasing optical power in the pulsed regime is to increase number of stages in the cascade structure. However, due to a low active region thermal conductivity,...
Show moreQuantum Cascade Lasers have recently gained considerable attention for their capability to emit infrared radiation in a broad infrared spectral region, very compact dimensions, and high optical power/efficiency. Increasing continuous wave optical power is one of the main research directions in the field. A straightforward approach to increasing optical power in the pulsed regime is to increase number of stages in the cascade structure. However, due to a low active region thermal conductivity, the increase in number of stages leads to active region overheating in continuous wave operation. In this work, an alternative approach to power scaling with device dimensions is explored: number of stages is reduced to reduce active region thermal resistance, while active region lateral size is increased for reaching high optical power level. Using this approach, power scaling for active region width increase from 10(&)#181;m to 20(&)#181;m is demonstrated for the first time. An analysis based on a simple semi-empirical model suggests that laser power can be significantly improved by increasing characteristic temperature T0 that describes temperature dependence of laser threshold current density.
Show less - Date Issued
- 2017
- Identifier
- CFE0007137, ucf:52299
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007137
- Title
- Imaging long-range orientational order in monolayers of amphiphilic molecules with scanning probe force microscope and liquid crystal optical amplification.
- Creator
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Liang, Wenlang, Fang, Jiyu, Deng, Weiwei, An, Linan, Huo, Qun, University of Central Florida
- Abstract / Description
-
Monolayers of amphiphilic molecules at interface provide a unique system for understanding the thermodynamic and rheological properties of quasi two-dimensional systems. They are also an excellent model accessible for studying cell membranes. The feature of long-range organization of molecular tilt azimuth in monolayers at the air/water interface is one of the most interesting findings over the past two decades, which leads to the formation rich and defined textures. By observing the changes...
Show moreMonolayers of amphiphilic molecules at interface provide a unique system for understanding the thermodynamic and rheological properties of quasi two-dimensional systems. They are also an excellent model accessible for studying cell membranes. The feature of long-range organization of molecular tilt azimuth in monolayers at the air/water interface is one of the most interesting findings over the past two decades, which leads to the formation rich and defined textures. By observing the changes in these textures, the transitions between tilted monolayer phases can be detected. We study the boojum and stripe textures formed in the liquid-condensed phase of pentadecanoic acid (PDA) monolayers at the air/water interface and find that they can be preserved after being transferred to glass substrates at low dipping speeds at a temperature lower than the room temperature. Frictional force microscopy confirms the long-range tilt order in the transferred boojums and stripes of PDA, implying the interaction of the PDA molecules with the glass surface does not change the tilt order. Polymerized stripe textures of pentacosadiynoic acid (PCA) monolayers can also be transferred onto solid substrates. Atomic force microscopy shows that the PCA stripe textures represent the regular variations of molecular packing densities in PCA monolayers. Furthermore, we find that the molecular orientation and packing density changes in monolayers can induce the local order of nematic liquid crystals. Due to the long-range orientation correlation of nematic liquid crystals, the boojum and stripe textures in monolayers can be observed by an optical microscope after liquid crystal optical amplification.
Show less - Date Issued
- 2011
- Identifier
- CFE0004498, ucf:49294
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004498
- Title
- Nanoscale Control of Gap-plasmon Enhanced Optical Processes.
- Creator
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Lumdee, Chatdanai, Kik, Pieter, Dogariu, Aristide, Kuebler, Stephen, Huo, Qun, University of Central Florida
- Abstract / Description
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Surface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive sensors, light emitters, and optical absorbers. A plasmon resonance mode of particular recent interest is the gap plasmon resonance that occurs on closely spaced metallic structures. In contrast to...
Show moreSurface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive sensors, light emitters, and optical absorbers. A plasmon resonance mode of particular recent interest is the gap plasmon resonance that occurs on closely spaced metallic structures. In contrast to plasmon resonances supported by isolated metal nanostructures, coupled nanostructures provide additional spectral and spatial control over the plasmon resonance response. For example, the resonance frequencies of metal nanoparticle dimers depend strongly on the gap size between the nanoparticles. Gap plasmons can produce local electric field enhancement factors that are several orders of magnitude stronger and more confined than surface plasmon resonances of isolated plasmonic nanospheres. The reliance of gap plasmons on few-nanometer separation between nanostructures makes it difficult to prepare gap-plasmon supporting structures with predictable resonance frequency and field enhancement. A structure that avoids this challenge is the film-coupled nanoparticle (NP). Similar to nanoparticle dimers, a nanoparticle on a supporting metallic film (or NP-on-a-mirror) can offer a strong coupling between the particle and its local environment, in this case the supporting film instead of adjacent nanoparticles, enabling strongly confined gap-plasmon modes. The NP-on-a-mirror geometry has been shown to produce reproducible gap plasmon resonances in a chemically and thermally robust, easy to fabricate structure. In this Thesis, we first present a scheme for controlling the gap plasmon resonance frequency of single gold nanoparticles using aluminum oxide coated metal films. We demonstrate experimentally and numerically that the gap-plasmon resonance of single gold nanoparticles can be tuned throughout the visible range by controlling the aluminum oxide thickness via anodization. In a separate study of Au NP on Al2O3 coated gold films it is shown that the oxide coating improves the stability of the structure under intense laser irradiation. An combined experimental and numerical analysis of the spectral response of Au NP on rough Au films shows that a film roughness of a few nanometer can affect the gap plasmon resonance in the absence of an oxide spacer layer. A photoluminescence study of single gold nanoparticles on an Al2O3 coated gold film shows that the gap-plasmon resonance of this type of plasmonic structure can increase gold photoluminescence by more than four orders of magnitude. Related numerical simulations reveal that the local photoluminescence enhancement of a gold nanoparticle on an Al2O3 coated gold film can be as high as one million near the particle-film junction. Finally, a new plasmonic sensing element was proposed based on our findings in the previous chapters. This proposed hole-in-one structure offers several attractive features including an easily optically accessible gap plasmon mode, while maintaining a relatively simple fabrication method. Taken together, the research presented in this Thesis demonstrates how the resonance frequency, field enhancement, mode polarization, structural stability, and structure reliability can be controlled at the nanoscale. The knowledge gained in the course of this work could lead to further development of nanophotonic devices that utilize extremely confined optical fields and precisely controlled resonance frequencies.
Show less - Date Issued
- 2015
- Identifier
- CFE0005972, ucf:50772
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005972
- Title
- Mechanism of Actin Bundle Assembly, Mechanics and Structure by Ion Interaction.
- Creator
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Castaneda, Nicholas, Kang, Hyeran, Huo, Qun, Gesquiere, Andre, University of Central Florida
- Abstract / Description
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The assembly of actin filaments into bundles plays an essential role in mechanical strength and dynamic reorganization of cytoskeleton. Divalent counterions at high concentrations promote bundle formation through electrostatic attraction between charged filaments. Although it has been hypothesized that specific cation interactions may contribute to salt-induced bundling, molecular mechanisms of how salt modulates bundle assembly and mechanics are not well established. Here we determine the...
Show moreThe assembly of actin filaments into bundles plays an essential role in mechanical strength and dynamic reorganization of cytoskeleton. Divalent counterions at high concentrations promote bundle formation through electrostatic attraction between charged filaments. Although it has been hypothesized that specific cation interactions may contribute to salt-induced bundling, molecular mechanisms of how salt modulates bundle assembly and mechanics are not well established. Here we determine the mechanical and dynamic properties of actin bundles with physiologically relevant cations. Using total internal reflection fluorescence (TIRF) microscopy, we measure the bending stiffness of actin bundles determined by persistence length analysis. We characterize real-time formation of bundles by dynamic light scattering intensity and direct visualization using TIRF microscopy. Our results show that divalent cations modulate bundle stiffness as well as time-dependent average bundle size. Furthermore, molecular dynamic simulations propose specificity for cation binding on actin filaments to form bundles. The work suggests that cation interactions serve a regulatory function in bundle assembly dynamics, mechanics, and structure.
Show less - Date Issued
- 2017
- Identifier
- CFE0006572, ucf:51307
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006572
- Title
- Self-Assembled Two-Component Organic Tubes: Structures and Applications.
- Creator
-
Liang, Wenlang, Fang, Jiyu, Huo, Qun, Deng, Weiwei, University of Central Florida
- Abstract / Description
-
Bile acids are physiologically important metabolites, which are synthesized in liver as the end products of cholesterol metabolism and then secreted into the intestines. They play a critical role in the digestion and absorption of fats and fat-soluble vitamins through emulsifications. The amphipathic and chiral nature of bile acids makes their unique building blocks for assembling supramolecular structures including vesicles, fibers, ribbons and hollow tubes. Lithocholic acid (LCA) is a...
Show moreBile acids are physiologically important metabolites, which are synthesized in liver as the end products of cholesterol metabolism and then secreted into the intestines. They play a critical role in the digestion and absorption of fats and fat-soluble vitamins through emulsifications. The amphipathic and chiral nature of bile acids makes their unique building blocks for assembling supramolecular structures including vesicles, fibers, ribbons and hollow tubes. Lithocholic acid (LCA) is a secondary bile acid. Our studies show LCA can self-assemble into helical tubes in aqueous solution by the linear aggregation and fusion of vesicles. The objective of this dissertation is to tune the structure of helical tubes and functionalize them by the co-assembly of ionic LCA and cationic cetyltrimethylammonium bromide (CTAB) and ionic LCA and cationic cyanine dye (CD), respectively. The first part of this dissertation focuses on the ionic-assembly of LCA and CTAB to synthesize the helical tubes with varied diameters and pitches. Our studies show that LCA and CTAB can self-assemble into helical tubes in NH4OH aqueous solution. The diameter of the helical tubes can be changed by adjusting the molar ratio of LCA and CTAB. The pitch of the helical tubes can be tuned by varying NH4OH concentrations. Differential scanning calorimetry studies indicate that there is a homogeneous composition distribution in the LCA/CTAB helical tubes. X-ray diffraction analysis studies show that the helical tubes have multibilayer walls with an average d-spacing of 4.11nm. We demonstrate that the helical tubes with varied diameters and pitches can be transformed into helical silica through the sol-gel transcription of tetraethoxysilane (TEOS). The second part of this dissertation is to use the ionic self-assembly of LCA and CD to design light-harvesting tubes by mimicking green sulfur bacteria that are known to be a highly efficient photosynthesizer. X-ray diffraction and optical spectra show that LCA and CD can co-assemble into J- or H-aggregate tubes, depending the condition under which the self-assembly occurs. We demonstrate the feasibility of using the J-aggregate nanotubes in the sensitive and selective detection of mercury (II) ions by the photoinduced electron transfer under sunlight. The presence of mercury (II) ions in aqueous solution could be detected for concentrations as low as 10 pM.
Show less - Date Issued
- 2013
- Identifier
- CFE0005201, ucf:50635
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005201
- Title
- A Complete Approach to Predict Biodistribution of Nanomaterials Within Animal Species from In-vitro Data.
- Creator
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Price, Edward, Gesquiere, Andre, Huo, Qun, Kolpashchikov, Dmitry, Rex, Matthew, Ebert, Steven, University of Central Florida
- Abstract / Description
-
Smart drug-design for antibody and nanomaterial-based therapies allows for optimization of drug efficacy and more efficient early-stage pre-clinical trials. The ideal drug must display maximum efficacy at target tissue sites, but to track and predict distribution to these sites, one must have a mechanistic understanding of the kinetics involved with the individual cells of the tissue itself. This process can be tracked through biological simulations coupled with in-vitro approaches, which...
Show moreSmart drug-design for antibody and nanomaterial-based therapies allows for optimization of drug efficacy and more efficient early-stage pre-clinical trials. The ideal drug must display maximum efficacy at target tissue sites, but to track and predict distribution to these sites, one must have a mechanistic understanding of the kinetics involved with the individual cells of the tissue itself. This process can be tracked through biological simulations coupled with in-vitro approaches, which result in a rapid and efficient in-depth understanding of drug transport within tissue vasculature and cellular environment. As a result, it becomes possible to predict drug biodistribution within live animal tissue cells without the need for animal studies. Herein, we use in-vitro assays to translate transport kinetics to whole-body animal simulations to predict drug distribution from vasculature into individual tissue cells for the first time. Our approach is based on rate constants obtained from an in-vitro assay that accounts for cell-induced degradation, which are translated to a complete animal simulation to predict nanomedicine biodistribution at the single cell level. This approach delivers predictions for therapies of varying size and type for multiple species of animals solely from in-vitro data. Thus, we expect this work to assist in refining, reducing, and replacing animal testing, while at the same time, giving scientists a new perspective during early stages of drug development.
Show less - Date Issued
- 2019
- Identifier
- CFE0007900, ucf:52747
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007900
- Title
- Light Scattering Property of Gold Nanoparticles with Applications to Biomolecule Detection and Analysis.
- Creator
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Zheng, Tianyu, Huo, Qun, Zou, Shengli, Gesquiere, Andre, Kang, Hyeran, Zhai, Lei, University of Central Florida
- Abstract / Description
-
Gold nanoparticles (AuNPs) have unique optical and chemical properties. Dynamic light scattering (DLS) is an analytical tool used routinely for nanoparticle size measurement. The combined use of AuNPs and DLS has led to a novel analytical assay technology called D2Dx (from diameter to diagnostics). Herein, my dissertation highlights the extended use of D2Dx for biomolecule detection and analysis. Under this general theme, Chapter 1 provides some background information of AuNPs, DLS, the...
Show moreGold nanoparticles (AuNPs) have unique optical and chemical properties. Dynamic light scattering (DLS) is an analytical tool used routinely for nanoparticle size measurement. The combined use of AuNPs and DLS has led to a novel analytical assay technology called D2Dx (from diameter to diagnostics). Herein, my dissertation highlights the extended use of D2Dx for biomolecule detection and analysis. Under this general theme, Chapter 1 provides some background information of AuNPs, DLS, the principle of D2Dx technique and its potential applications. Chapter 2 summarizes a study on the effect of AuNP concentrations and laser power on the hydrodynamic size measurement of AuNPs by DLS. This study demonstrated the multiple scattering effect on DLS analysis, and how to use the exceptionally high sensitivity of DLS in AuNP aggregate detection for bioassay design and development. Chapter 3 explores a cooperative interaction between AuNP and certain proteins in blood serum that are key to the immune system, leading to a novel diagnostic tool that can conveniently monitor the humoral immunity development from neonates to adults and detect active infections in animals. Chapter 4 reports an application of D2Dx technique for acute viral infection detection based on the active immune responses elicited from mouse models infected with influenza virus. Chapter 5 describes another application of D2Dx for prostate cancer detection. The D2Dx assay identifies prostate cancer patients from non-cancer controls with improved specificity and sensitivity than PSA test. Chapter 6 demonstrates the use of AuNPs and DLS for hydrodynamic size measurement of protein disulfide isomerase with two different conformations. Chapter 7 investigates the concentration-dependent self-assembling behavior of ribostamycin through its interaction with AuNPs in aqueous solution. Overall, this dissertation established several lines of applications of using AuNPs and DLS for biomolecular research and in vitro diagnostics.
Show less - Date Issued
- 2018
- Identifier
- CFE0007385, ucf:52056
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007385
- Title
- Improved system for fabrication and characterization of nanophotonic devices by multi-photon lithography.
- Creator
-
Sharma, Rashi, Kuebler, Stephen, Zou, Shengli, Huo, Qun, Beazley, Melanie, Phanstiel, Otto, University of Central Florida
- Abstract / Description
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A new system for multi-photon lithography (MPL) was developed and used to fabricate three-dimensional (3D) structures with higher aspect ratio, better resolution, improved fidelity, and reduced structural distortion relative to a conventional implementation of MPL.A set of curved waveguides (Rbend = 19 (&)#181;m, and 38 (&)#181;m) and straight waveguides (length = 50 (&)#181;m, Rbend = ?) were fabricated in an epoxide photopolymer and optically characterized using light having a wavelength in...
Show moreA new system for multi-photon lithography (MPL) was developed and used to fabricate three-dimensional (3D) structures with higher aspect ratio, better resolution, improved fidelity, and reduced structural distortion relative to a conventional implementation of MPL.A set of curved waveguides (Rbend = 19 (&)#181;m, and 38 (&)#181;m) and straight waveguides (length = 50 (&)#181;m, Rbend = ?) were fabricated in an epoxide photopolymer and optically characterized using light having a wavelength in vacuum of ?0 = 2.94 (&)#181;m. The optical performance of the waveguides was compared to novel spatially-variant photonic crystals (SVPCs) previously studied in the group. The waveguides were found to guide light with 90% lower efficiency, due to mode leakage. The study provides further evidence that SVPCs operate not through total internal reflection, but rather through self-collimation, as designed.3D uniform-lattice photonic crystals (ULPCs) were fabricated by MPL using a commercial acrylate photopolymer. The ULPCs were optically characterized at ?0 = 1.55 (&)#181;m. A laser beam with adjustable bandwidth was used to measure the self-collimation in the ULPCs. For the low bandwidth beam, vertically polarized light was self-collimated, whereas horizontally polarized light diverged. The transmission efficiency of the ULPCs was also measured as a function of fill factor. The ULPC having a fill factor of 48% exhibited 80% transmission.An etching process was also developed for non-destructively removing Au/Pd coatings that must be deposited onto structures to image them by scanning electron microscopy. The structural and optical integrity of the samples was found to be maintained despite etching. The sputter-coated sample sustained no structural damage when exposed to the ?0 = 1.55 (&)#181;m. However, the metal coating resulted in diminished transmission efficiency due to the high reflection of the 1.55 (&)#181;m beam by the metal coating.
Show less - Date Issued
- 2018
- Identifier
- CFE0007767, ucf:52380
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007767
- Title
- Developing surface engineered liquid crystal droplets for sensing applications.
- Creator
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Bera, Tanmay, Fang, Jiyu, Suryanarayana, Challapalli, Huo, Qun, Cho, Hyong, Deng, Weiwei, Wu, Shintson, University of Central Florida
- Abstract / Description
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Diagnosis plays a very crucial role in medicine and health care, which makes biosensors extremely important in modern technological context. Till date, various types of biosensors have been developed that are capable of detecting a wide range of biologically important species with great sensitivity and selectivity. However, most of these sensing units require highly sophisticated instrumentation and often lack the desired portability. Liquid crystal (LC) droplets, on the other hand, are a new...
Show moreDiagnosis plays a very crucial role in medicine and health care, which makes biosensors extremely important in modern technological context. Till date, various types of biosensors have been developed that are capable of detecting a wide range of biologically important species with great sensitivity and selectivity. However, most of these sensing units require highly sophisticated instrumentation and often lack the desired portability. Liquid crystal (LC) droplets, on the other hand, are a new type of functional material that are finding increasing research attention as a new sensing unit due to their tunable optical property, high surface area, portability and cost-effectiveness. In this dissertation, functionalized LC droplets for biosensing at aqueous-LC interface are highlighted. Chemically functionalized LC droplets dispersed in aqueous solution were prepared by the self-assembly of amphiphilic molecules at the aqueous/LC interface. These functionalized LC droplets showed a well-defined director of configuration and a specific optical pattern when observed with a polarizing light microscope. It was discovered that the interaction of chemically functionalized LC droplets with an analyte triggers transition of the director of configuration of the LC within the droplets, providing a simple and unique optical sign for the detection of the analyte. Moreover, the director of configuration transition happened in a concentration dependent manner, allowing both qualitative and quantitative detection of the analyte. The sensitivity of chemically functionalized LC droplets depends not only on the nature of amphiphilic molecules but also the size and number of the droplets.The dissertation essentially deals with the application of these chemically functionalized LC droplets in detecting several biologically important species. It was observed that the adsorption of charged macromolecules (dendrimers, proteins, and viruses) on polyelectrolyte functionalized LC droplets triggered a bipolar-to-radial configuration transition based on the polar verses non-polar interaction. By using a simple optical microscope, microgram per milliliter concentrations of bovine serum albumin, cowpea mosaic virus, and tobacco mosaic virus could be detected in aqueous solution. The detection limit of Mastoparan X polypeptide decorated LC droplets in detecting E. coli could reach to approximately 10 bacteria per milliliter. In this case, the high affinity of the polypeptide towards the bacterial causes the former to detach from the LC droplets, triggering the director of configuration transition of the LC inside the droplets. Finally, surfactant decorated LC droplets were used to detect lithocholic acid (LCA), a toxic bile acid used as a specific biomarker for colon cancers. In this case, the director of configuration transition of the LC inside the droplets is a result of the replacement of the surfactant from the aqueous/LC interface by LCA. The microgram per milliliter concentration of LCA, a clinically significant concentration, could be easily detected by changing the length of surfactants. These studies highlight the novel use of surface functionalized LC droplets to detect biologically important species. Due to their tunable optical property, coupled with high surface area and portability, surface functionalized LC droplets have great potentials in the design of next generation biosensors.
Show less - Date Issued
- 2012
- Identifier
- CFE0004307, ucf:49471
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004307
- Title
- Theoretical-Experimental Study of the Two-Photon Circular Dichroism of Helicenes and Aromatic Amino Acids in the UV Region: From the Structure-Property Relationship to the Final Implementation.
- Creator
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Vesga Prada, Yuly Katherine, Hernandez, Florencio, Huo, Qun, Chumbimuni Torres, Karin, Zou, Shengli, Tatulian, Suren, University of Central Florida
- Abstract / Description
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Two-photon circular dichroism (TPCD) has been recognized for its exceptional spectroscopic ability for the structural and conformational analysis of chiral systems due to its high sensitivity to small peptide structural distortions. In 2008, Hernandez and co-workers demonstrated TPCD experimentally by the development of the Double L-scan technique. Since then, we have been working on a systematic theoretical-experimental study of chiral molecules using TPCD. In this dissertation, I present my...
Show moreTwo-photon circular dichroism (TPCD) has been recognized for its exceptional spectroscopic ability for the structural and conformational analysis of chiral systems due to its high sensitivity to small peptide structural distortions. In 2008, Hernandez and co-workers demonstrated TPCD experimentally by the development of the Double L-scan technique. Since then, we have been working on a systematic theoretical-experimental study of chiral molecules using TPCD. In this dissertation, I present my contribution to the continuation to the study of the structure-property relationship of TPCD in molecules with axial chirality in solution, as well as the implementation of the TPCD measurements in the near- and far-UV regions. Employing a theoretical-experimental approach I will discuss: 1) the effect of the pulse width of the excitation source on the TPCD spectra of biaryl derivatives, 2) the theoretical study of the TPCD signal in the far-UV on molecular structures simulating aromatic amino acid residues in proteins with secondary structures, and 3) the pros and cons of the implementation of the FUV-TPCD spectrometer. The outcomes of my research reveal the potential of TPCD for the conformational analysis of relatively complex molecular systems such as peptides in the far-UV region, an area never accessed before. Additionally, we exposed the applicability of TPCD as a complimentary method to standard electronic circular dichroism (ECD) for the study of complex structures. Finally, I demonstrate for the very first time experimental evidence of TPCD in the near- to Far-UV region.
Show less - Date Issued
- 2016
- Identifier
- CFE0006514, ucf:51375
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006514
- Title
- Development of a nano-sensing approach and a portable prototype for real-time detection and quantification of free mercury in stream-flow: combining science and engineering in pro of the environment.
- Creator
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Chemnasiri, Warinya, Hernandez, Florencio, Kuebler, Stephen, Zou, Shengli, Uribe Romo, Fernando, Huo, Qun, University of Central Florida
- Abstract / Description
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Mercury (Hg) is a well-known hazardous environmental contaminant existing in several forms, but all are toxic to human in one way or the others. Since Hg usually settles into water polluting the environment and accumulating in living organisms, it is crucial to monitor Hg levels in the aquatic ecosystem. Although there are many well established techniques currently used to detect Hg, most of them require elaborate and time-consuming sample preparation and pre-concentration procedures, as well...
Show moreMercury (Hg) is a well-known hazardous environmental contaminant existing in several forms, but all are toxic to human in one way or the others. Since Hg usually settles into water polluting the environment and accumulating in living organisms, it is crucial to monitor Hg levels in the aquatic ecosystem. Although there are many well established techniques currently used to detect Hg, most of them require elaborate and time-consuming sample preparation and pre-concentration procedures, as well as costly and bulky equipment that limit their practical application in the field. In order to overcome the existent limitations in Hg determination methods, Hernandez and co-workers proposed the first surface Plasmon resonance (SPR) (-) based Hg sensor using gold nanorods (AuNRs) that offers high sensitivity and selectivity, attributed to the strong affinity between Au and Hg. In this dissertation, I first present my contribution to the understanding of the effect of size and aspect ratio of AuNRs on the limit of detection (LOD) and the dynamic range (DR) of the SPR-based Hg sensor using the qualitative model. In this part I demonstrate how both sensitivity and DR can be improved simultaneously via a modified wet chemistry procedure. Then, I show our approach towards the immobilization of AuNRs silane coated glass slides to expand the application of the SPR-based Hg sensor to stream-flow. Finally, I present the design and fabrication of the first real prototype of the SPR-based Hg sensor, and its application in stream-flow detection and speciation of mercury in the environment. The outcomes of my research have resulted in an innovative real-time portable Hg sensor apparatus with the desired high sensitivity, selectivity and DR to be used in stream-flow applications in Oak Ridge National Labs sites.
Show less - Date Issued
- 2015
- Identifier
- CFE0006283, ucf:51589
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006283
- Title
- Non-Oxide Porous Ceramics from Polymer Precursor.
- Creator
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Yang, Xueping, An, Linan, Fang, Jiyu, Zhai, Lei, Huo, Qun, Wu, Shintson, University of Central Florida
- Abstract / Description
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Non-oxide porous ceramics exhibit many unique and superior properties, such as better high-temperature stability, improved chemical inertness/corrosive resistance, as well as wide band-gap semiconducting behavior, which lead to numerous potential applications in catalysis, high temperature electronic and photonic devices, and micro-electromechanical systems. Currently, most mesoporous non-oxide ceramics (e.g. SiC) are formed by two-step templating methods, which are hard to adjust the pore...
Show moreNon-oxide porous ceramics exhibit many unique and superior properties, such as better high-temperature stability, improved chemical inertness/corrosive resistance, as well as wide band-gap semiconducting behavior, which lead to numerous potential applications in catalysis, high temperature electronic and photonic devices, and micro-electromechanical systems. Currently, most mesoporous non-oxide ceramics (e.g. SiC) are formed by two-step templating methods, which are hard to adjust the pore sizes, and require a harmful etching step or a high temperature treatment to remove the templates.In this dissertation, we report a novel technique for synthesizing hierarchically mesoporous non-oxide SiC ceramic from a block copolymer precursor. The copolymer precursors with vairing block length were synthesized by reversible addition fragmentation chain transfer polymerization. The block copolymers self-assemble into nano-scaled micelles with a core-shell structure in toluene. With different operation processes, hollow SiC nanospheres and bulk mesoporous SiC ceramics were synthesized after the subsequent pyrolysis of precorsur micelles. The resultant SiC ceramics have potential applications in catalysis, solar cells, separation, and puri?cation processes.The polymer synthesis and pyrolysis process will investigated by NMR, FTIR, GPC, TEM, and TGA/DSC. The morphology and structure of synthesised SiC hollow spheres and mesoporous ceramics were analyzed by SEM, TGA/DSC and BET/BJH analysis.Besides forming core shell micelles in selective solvent Toluene, we found that PVSZ-b-PS could also exhibit this property in the air water interface. By inducing the Langmuir-Blodgett deposition, a precursor monolayer with homogeously distributed povinylsilazane particles deposited on silicon wafer synthesized by spreading the diblock copolymer PVSZ-b-PS in the air water interface. After the pyrolysis process, orderly arranging SiC nano particles formed from the polymer precursor monolayer doped on the surface of silicon wafer, which shows great potential as an optoelectronic material. The deposition process and the relationship between compress pressure and monolayer morphology were studies, and the structure of monolayer and SiC dots were investigated by AFM, SEM.
Show less - Date Issued
- 2014
- Identifier
- CFE0005564, ucf:50274
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005564
- Title
- The Characterization of Condom Lubricants and Personal Hygiene Products using DART-TOFMS and GC- MS and The Investigation of Gold Nanoparticle Behavior in Water and the Interaction with Blood Serum Proteins.
- Creator
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Moustafa, Yasmine, Huo, Qun, Bridge, Candice, Sigman, Michael, Baudelet, Matthieu, Popolan-Vaida, Denisia, Ni, Liqiang, University of Central Florida
- Abstract / Description
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This dissertation is divided into two independent research projects. First, condom lubricants, sexual lubricants, and personal hygiene products (PHPs) were studied using direct analysis in real time-time-of-flight-mass spectrometry (DART-TOFMS) and gas chromatography-mass spectrometry (GC-MS). The purpose addressed the concern of perpetrators resorting to new tactics, i.e. using condoms to remove seminal fluid that could provide a DNA link to a suspect, leading to the need of the...
Show moreThis dissertation is divided into two independent research projects. First, condom lubricants, sexual lubricants, and personal hygiene products (PHPs) were studied using direct analysis in real time-time-of-flight-mass spectrometry (DART-TOFMS) and gas chromatography-mass spectrometry (GC-MS). The purpose addressed the concern of perpetrators resorting to new tactics, i.e. using condoms to remove seminal fluid that could provide a DNA link to a suspect, leading to the need of the consideration of condom lubricants as pieces of sexual assault evidence. Due to condom lubricants having a chemical composition resembling PHPs, the investigation of both sample groups was analyzed to prevent false positives. Although past research has focused on the identification of major lubricant groups and additives, the discernment between such samples is insufficient. The discriminatory capability and rapid analysis of samples using DART-TOFMS was illustrated through resolution among the sample groups and higher classification rates. Here, lubricant analysis was introduced as a viable source of evidence, with a scheme detailing their discrimination from common hygiene products using DART-TOFMS as a robust tool for the analysis of sexual assault evidence. Second, gold nanoparticles (AuNPs) were characterized using dynamic light scattering (DLS), Ultraviolet-Visible spectroscopy (UV-VIS), dark field Imaging (DFM), and Transmission electron microscopy (TEM). Following characterization, AuNPs were used in protein adsorption study from blood serum concentration and to observe how the differences in their characterization affected their interactions with blood serum proteins. AuNPs are an interest in the bioanalytical sector due to their optical properties, scattering of light, and high surface-to-volume ratio. A common issue plagues the field: the difficulty of inter/intra laboratory reproducibility from one characterization technique. This further affects the understanding of how AuNPs may react for diagnostic and other applications. The importance of a comprehensive characterization protocol for AuNP products and the need for manufacturers to include product specifications is demonstrated in this study.
Show less - Date Issued
- 2019
- Identifier
- CFE0007842, ucf:52814
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007842
- Title
- Structure and Properties of Polymer-Derived SiBCN Ceramics.
- Creator
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Chen, Yaohan, An, Linan, Fang, Jiyu, Xu, Chengying, Zhai, Lei, Huo, Qun, Gong, Xun, University of Central Florida
- Abstract / Description
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Polymer-derived ceramics (PDCs) are a unique class of multifunctional materials synthesized by thermal decomposition of polymeric precursors. Due to their unique and excellent properties and flexible manufacturing capability, PDC is a promising technology to prepare ceramic fibers, coatings, composites and micro-sensors for high-temperature applications. However, the structure-property relationships of PDCs have not been well understood. The lack of such understandings drastically limited the...
Show morePolymer-derived ceramics (PDCs) are a unique class of multifunctional materials synthesized by thermal decomposition of polymeric precursors. Due to their unique and excellent properties and flexible manufacturing capability, PDC is a promising technology to prepare ceramic fibers, coatings, composites and micro-sensors for high-temperature applications. However, the structure-property relationships of PDCs have not been well understood. The lack of such understandings drastically limited the further developments and applications of the materials.In this dissertation, the structure and properties of amorphous polymer-derived silicon carbonitride (SiCN) and silicoboron carbonitride (SiBCN) have been studied. The SiCN was obtained using commercially available polysilazane as pre-ceramic precursor, and the SiBCN ceramics with varied Si-to-B ratio were obtained from polyborosilazanes, which were synthesized by the hydroboration and dehydrocoupling reaction of borane and polysilazane. The structural evolution of polymer-derived SiCN and SiBCN ceramics from polymer to ceramics was investigated by NMR, FTIR, Raman, EPR, TG/DTA, and XRD. The results show a phase-separation of amorphous matrix and a graphitization of (")free(") carbon phase, and suggest that the boron doping has a great influence on the structural evolution. The electric and dielectric properties of the SiCN and SiBCNs were studied by I-V curves, LCR Meter, and network analyzer. A new electronic conduction mechanism and structure model has been proposed to account for the relationships between the observed properties and microstructure of the materials. Furthermore, the SiBCN ceramics showed the improved dielectric properties at characterization temperature up to 1300 (&)#186;C, which allows the fabrication of ultrahigh-temperature wireless microsensors for extreme environments.
Show less - Date Issued
- 2012
- Identifier
- CFE0004195, ucf:49014
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004195
- Title
- Integral Representations of Positive Linear Functionals.
- Creator
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Siple, Angela, Mikusinski, Piotr, Atanasiu, Dragu, Dutkay, Dorin, Han, Deguang, Lee, Junho, Brennan, Joseph, Huo, Qun, University of Central Florida
- Abstract / Description
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In this dissertation we obtain integral representations for positive linear functionals on commutative algebras with involution and semigroups with involution. We prove Bochner and Plancherel type theorems for representations of positive functionals and show that, under some conditions, the Bochner and Plancherel representations are equivalent. We also consider the extension of positive linear functionals on a Banach algebra into a space of pseudoquotients and give under conditions in which...
Show moreIn this dissertation we obtain integral representations for positive linear functionals on commutative algebras with involution and semigroups with involution. We prove Bochner and Plancherel type theorems for representations of positive functionals and show that, under some conditions, the Bochner and Plancherel representations are equivalent. We also consider the extension of positive linear functionals on a Banach algebra into a space of pseudoquotients and give under conditions in which the space of pseudoquotients can be identified with all Radon measures on the structure space. In the final chapter we consider a system of integrated Cauchy functional equations on a semigroup, which generalizes a result of Ressel and offers a different approach to the proof.
Show less - Date Issued
- 2015
- Identifier
- CFE0005713, ucf:50144
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005713
