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Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar
Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar
Doctoral Dissertations
The ionomer-membrane interface in a membrane electrode assembly connects the catalyst and membrane and allows hydrated protons to move between the catalyst and membrane. The continuous operation of the polymer membrane electrolyte fuel cell at high temperature and/or in frequent freeze/thaw cycles leads to membrane degradation and delamination of the interface, which lower the proton conductivity. In this dissertation, we modeled the chemical degradation and proton conductivity of perfluorosulfonic acid (PFSA) ionomers by ab initio calculations and macroscopic modeling. All ab initio calculations were performed using Gaussian 03 suites of program by employing B3LYP/6-311++G** method/basis set. The macroscopic modeling involves …
Bioreactor System Designs For Lipase-Catalyzed Synthesis Of Saccharide- Fatty Acid Esters In Solvent-Free Media, Ran Ye
Doctoral Dissertations
As nontoxic biobased surfactants derived from plant oils and cellulose or starch, saccharide-fatty acid esters are widely used in cosmetics, food, and pharmaceutical industries due to their biocompatibility, biodegradability as well as antimicrobial activity. Generally, saccharide-fatty acid esters are synthesized chemically under high pressure, temperature and the presence of alkaline or acid catalysts leading to low-quality products (chemo-degradation of double bonds and oxygenated moieties) and large amounts of byproducts. In contrast, biocatalytic synthesis enhances sustainability: near-ambient pressure and temperature, the absence of toxic, acids and bases catalysts, and improved selectivity of products. For lipase-catalyzed synthesis under nearly anhydrous conditions, the …
Protein Engineering For The Enhanced Photo-Production Of Hydrogen By Cyanobacterial Photosystem I, Ifeyinwa Jane Iwuchukwu
Protein Engineering For The Enhanced Photo-Production Of Hydrogen By Cyanobacterial Photosystem I, Ifeyinwa Jane Iwuchukwu
Doctoral Dissertations
Photosystem I (PSI) from plants, algae, and cyanobacteria can mediate H2 evolution in vivo and in vitro. A simple, self-platinization procedure that permits stable PSI-mediated H2 evolution in vitro has been developed. The H2 evolution capabilities of PSI from Thermosynechococcus elongatus have been characterized. This organism utilizes cytochrome c6 (cyt c6) as the e- donor to P700. Using a solution-based, self-organized platinization of the PSI nanoparticles, this study demonstrates a sodium ascorbate-cyt-PSI-Pt-H2 electron transport and proton reduction system that yields light-dependent H2. The system was thermostable with H2 evolution increasing up to 55°C. In addition, stability studies have shown the …