published_or_final_version / abstract / toc / Biochemistry / Doctoral / Doctor of Philosophy

Understanding the orientation of small organic acid modifiers on metal oxide electrodes is important in advancing the field of organic photovoltaics (OPVs). In this work, the orientation of a group of these small organic acid modifiers will be investigated on indium zinc oxide (IZO). Polarization modulation-infrared reflectance-absorbance spectroscopy (PM-IRRAS) is the primary technique used to determine these orientations. In order to determine orientations from PM-IRRAS data, other chemical and physical properties of the modifiers, such as density and surface coverage, must be experimentally determined. Neutral buoyancy is used to determine the density of the modifiers, while X-ray photoelectron spectroscopy (XPS) is used to estimate surface coverage of these modifiers on IZO. These techniques are also used to determine binding mode of these modifiers on IZO. The tilt angles (θ) were found to be 50 ± 3°, 64 ± 2°, and 43 ± 3° for F₅BnPA, F₅BnCA, and F₅BnHA, respectively, meaning that the phenyl ring in F₅BnHA is more perpendicular to the surface while the phenyl ring in F₅BnCA more parallel to the surface. All three modifiers were also found to bind to IZO in a bidentate manner. In contrast, F₅BnSA etches away significant portions of the IZO substrate.

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Advances in analytical chemistry have resulted in a growing body of literature showing measurable concentrations of pharmaceuticals in both drinking and wastewater. Removal of such chemicals is typically inefficient and often poorly characterized. To characterize one such method of removal (micellar enhanced ultrafiltration, (MEUF)), interactions of a cetyl trimethylammonium bromide (CTABr) surfactant and sulfonamide antibiotics were examined by NMR and semi-equilibrium dialysis (SED). The locus and orientation of binding in a micelle was established for seven sulfonamides by 1H NMR, and it was found that hydrophilic sulfonamides showed weak coordination with the micelle, whereas hydrophobic sulfonamides penetrated into the micellar interior with coordination of the SO2NH group to the charged surface layer. Binding constants were determined by 1H NMR and showed apparent order of magnitude differences between nuclei. Several compounds were unable to be characterized in this manner due to low change in chemical shift with addition of CTABr. SED was performed as an alternative method to determine binding constants. Values determined in this manner were higher than those determined by 1H NMR. Binding constants were converted into changes in Gibbs free energy and used to evaluate and, where necessary, modify the orientation and locus proposed by 1H NMR. Attempts are made to correlate binding constants with octanol-water partition coefficients to determine if a free energy relationship can be derived. Characterization of these systems may allow for a predictive methodology to determine the MEUF removal efficiencies of new sulfonamide and surfactant combinations. It is also hoped that this work may be generalized to predict MEUF efficiency for a wide range of contaminants that might be found in wastewater. / Thesis (Master, Chemistry) -- Queen's University, 2011-01-31 09:46:28.248

This thesis deals with two aspects of operators within the framework of Government and Binding theory; (i) how they are assigned their scope, and (ii) how they are licensed. In an attempt to answer these questions, the relation of Move $ alpha$ (such as scrambling, NP-movement, and wh-movement) to the scope of operators and the licensing of wh-elements, negative polarity items, and adverbs are examined. It is argued that scope assignment is dictated by the Scope Principle and the Empty Category Principle. It is also argued that licensing of operators is determined by the Feature-Dependent Item Criterion. These principles and criterion make use of the concept of Government Theory Compatibility, which is built into Relativized Minimality. It is suggested that this concept should be characterized in terms of a set of lexical features. The approach advocated here accounts for the interpretive and distributional behavior of operators without recourse to parameterization of LF principles.

The mouse node is the structural equivalent of Spemann's Organizer. The transcription factor Foxa2 (HNF3beta) is required for node and notochord specification and its enhancer has been characterized to a 500bp element that drives the expression of a reporter gene to the node and notochord in transgenic embryos. / The aim of the study was to identify sequence elements, within this enhancer, required to drive node/notochord specific-expression. Since, in the Xenopus organizer, Siamois activates organizer-specific gene expression, it was tested whether this factor could activate expression from the Foxa2 node-specific enhancer. Using deletion analysis, the response element was mapped to a 33bp region and it was shown that this element was both necessary and sufficient for reporter gene activation by X-Siamois . Furthermore, it was shown that X-Siamois can bind this DNA element and two sequence motifs required for binding and transactivation by X-Siamois were identified. Preliminary results suggest that the 33bp element, within the 500bp enhancer, is required for the maintenance of expression in the notochord of transgenic mice.

Liver fatty acid binding protein (L-FABP) binds and translocates many lipophilic substrates within the cytoplasm including long chain fatty acids. Moreover it was reported that L-FABP possesses antioxidative properties within hepatocytes. However, the mechanism of L-FABP’s antioxidative activity remains to be determined. Peroxisome proliferator activated receptor (PPAR) agonists and antagonists can regulate L-FABP levels. However, it needs to be investigated how PPAR agonists and antagonists regulate L-FABP expression. And whether the altered expression of L-FABP by these agents will affect its antioxidative properties within hepatocytes remains unclear. In this thesis we employed clofibrate (PPARα agonist), MK886 (PPARα antagonist), and GW9662 (PPARγ antagonist) to elucidate the mechanism whereby PPAR regulate L-FABP expression and what effect such expression has on the antioxidant activity of L-FABP in CRL-1548 hepatoma cells. Clofibrate served to upregulate L-FABP expression while MK886 and GW9662 were employed to inhibit L-FABP expression. The principal findings revealed that clofibrate treatment enhanced L-FABP mRNA stability and transcription, which resulted in increased L-FABP levels, while MK866 and GW9662 reduced these levels. We also demonstrated that increases in L-FABP levels were associated with reduced cytosolic reactive oxygen species (ROS), while L-FABP siRNA knockdown resulted in a decrease in L-FABP expression and an associated increase in ROS levels. The antioxidant mechanism of recombinant rat L-FABP in the presence of a hydrophilic (AAPH) and lipophilic (AMVN) free radical generators was also evaluated. Recombinant rat L-FABP was produced in E. coli and its amino acid sequence was confirmed by MALDI QqTOF MS. Antioxidant activity was assayed using the thiobarbituric acid method. Ascorbic acid served as a positive control for the AAPH reaction while α-tocopherol was used as a positive control for the AMVN reaction. The antioxidant activity of recombinant L-FABP was greater when free radicals were generated with AAPH than AMVN. Oxidative modification of L-FABP included up to five methionine oxidative peptides with a total of 80 Da mass shift compared to native L-FABP. These findings suggest that the mechanism of L-FABP’s antioxidant activity involved the reaction of methionine with free radicals. In conclusion, L-FABP expression is regulated by PPAR agonists and antagonists through transcription and mRNA stability. Moreover, methionine residues appear to play an important role in the antioxidative activity of L-FABP.

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