View All Items
(1 - 2 of 2)
- Title
- METHOD FOR DETERMINATION OF SINGLET OXYGEN QUANTUM YIELDS FOR NEW FLUORENE-BASED PHOTOSENSITIZERS IN AQUEOUS MEDIA FOR THE ADVANCEMENT OF PHOTODYNAMIC THERAPY.
- Creator
-
Grabow, Wade William, Belfield, Kevin, University of Central Florida
- Abstract / Description
-
Photodynamic therapy (PDT) has been investigated over the past three decades and is currently an approved therapeutic modality for skin cancer, the treatment of superficial bladder, early lung and advanced esophageal cancers, and age-related macular degeneration in a number of countries. In PDT, the absorption of light by a chromophore generates cytotoxic species such as reactive singlet oxygen, leading to irreversible destruction of the treated tissue. The measurement of the singlet oxygen...
Show morePhotodynamic therapy (PDT) has been investigated over the past three decades and is currently an approved therapeutic modality for skin cancer, the treatment of superficial bladder, early lung and advanced esophageal cancers, and age-related macular degeneration in a number of countries. In PDT, the absorption of light by a chromophore generates cytotoxic species such as reactive singlet oxygen, leading to irreversible destruction of the treated tissue. The measurement of the singlet oxygen quantum yield is an important determinant used to evaluate the efficiency of new photodynamic therapy agents developed in the laboratory, to screen potential photosensitizers in aqueous media.The singlet oxygen quantum yield is a quantitative measurement of the efficiency in which photosensitizers are able to use energy, in the form of light, to convert oxygen in the ground state to the reactive species singlet oxygen useful in photodynamic therapy. Singlet oxygen quantum yields of photosensitizers differ when measured in different solvents. The majority of the existing quantum yield values found in literature for various photosensitizers are documented with the sensitizers in organic solvents though values in aqueous media are more valuable for actual applications. Determination of accurate and precise quantum yield values in aqueous solution is a much more difficult problem than in organic media. Problems in aqueous solution arise primarily from the physicochemical properties of singlet oxygen in water. Singlet oxygen has a much shorter lifetime in water than it does in organic solvents, causing challenges with respect to quantitative detection of singlet oxygen.The ensuing pages are an attempt to explore the theory and document the procedures developed to provide the accurate measurement of singlet oxygen in aqueous media. Details of this experimental method and singlet oxygen quantum yield results of new compounds relative to established photosensitizers will be presented.
Show less - Date Issued
- 2004
- Identifier
- CFE0000029, ucf:46138
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000029
- Title
- An Adhesive Vinyl-Acrylic Electrolyte and Electrode Binder for Lithium Batteries.
- Creator
-
Tran, Binh, Zhai, Lei, Zou, Shengli, Kuebler, Stephen, Hernandez, Florencio, Gesquiere, Andre, University of Central Florida
- Abstract / Description
-
This dissertation describes a new vinyl-acrylic copolymer that displays great potential for applications in lithium ion batteries by enabling novel, faster, safer and cost-effective processes. Understanding the chemistry of materials and processes related to battery manufacturing allows the design of techniques and methods that can ultimately improve the performance of existing batteries while reducing the cost. The first and second parts of this dissertation focuses on the free radical...
Show moreThis dissertation describes a new vinyl-acrylic copolymer that displays great potential for applications in lithium ion batteries by enabling novel, faster, safer and cost-effective processes. Understanding the chemistry of materials and processes related to battery manufacturing allows the design of techniques and methods that can ultimately improve the performance of existing batteries while reducing the cost. The first and second parts of this dissertation focuses on the free radical polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA), methyl methacrylate (MMA), and isobutyl vinyl ether (IBVE) monomers to afford a vinyl-acrylic poly(PEGMA-co-MME-co-IBVE) random copolymer and the investigation of its properties as a soluble, amorphous, and adhesive electrolyte that is able to permanently hold 800 times its own weight. Such material properties envision a printable battery manufacturing procedure, since existing electrolytes lack adhesion at a single macromolecular level. Electrolytes can also be used as an electrode binder so long as it has structural integrity and allows ion transfer to and from the active electrode material during insertion/extraction processes. In the third section, the use of this electrolyte as a water-soluble binder for the aqueous fabrication of LiCoO2 cathodes is presented. Results of this study demonstrated the first aqueous process fabrication of thick, flexible, and fully compressed lithium ion battery electrodes by using commercial nickel foam as a supporting current collector. This feat is rather impressive because these properties are far superior to other aqueous binders in terms of material loading per electrode, specific area capacity, durability, and cell resistance. Finally, the fourth section expands on this concept by using the poly(PEGMA-co-MMA-co-IBVE) copolymer for the aqueous fabrication of a low voltage Li4Ti5O12 anode type electrode. Altogether, results demonstrate as a proof of concept that switching the current toxic manufacturing of lithium-ion batteries to an aqueous process is highly feasible. Furthermore, new electrode manufacturing techniques are also deemed possible.
Show less - Date Issued
- 2013
- Identifier
- CFE0004761, ucf:49780
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004761
