Three different B-site additives, Mg1/3Nb2/3, Zr4+, and Cu1/2W1/2, were added to BNT ceramics in varying concentrations. These were abbreviated as BNMN, BNZ, and BNCW, respectively. The compositions were calcined to form a perovskite structure, ground to a fine powder, pressed into tablets and sintered to form dense ceramics. XRD analysis confirmed the formation of the perovskite phase. The electro-mechanical properties of the ceramics were evaluated. There were improvements in the low-field room temperature dielectric constant of 30% with 25% BNMN, 13% with 10% BNZ, and 16% with 2% BNCW. Higher concentrations of the additives degraded the dielectric performance. The conductivity of the BNT ceramics was reduced with very small concentrations (0.25 to 0.5%) of each of the additives. This reduction was maintained at the higher concentrations of the additives, which allowed for higher electric fields to be applied during both the poling process and the strain measurements. Improvements of approximately 30% in the d33 values were found at concentrations of 0.5% of each of the additives, but higher concentrations of the additives degraded the d33 values. The coercive field was affected by the additions to BNT. Increasing concentrations of BNMN reduced the coercive field in bipolar strain measurements. This was accompanied by a reduction in the remanent strain. Small additions (0.5 to 1.5%) of BNZ resulted in an increase in the coercive field by about 12%, followed by a 25% decrease at 5% BNZ. The remanent strain followed the same pattern. All concentrations of BNCW studied reduced the coercive field by about 12%. The remanent strain increased by 25% at 0.5% BNCW, and decreased by 42% at 2.5% BNCW. The electro-mechanical results for the BNMN and BNZ additives were compared to the behaviours of their lead-based counterparts, PMN and PZ. There was no consistent trend in the response of the electromechanical properties to the additions between the current lead-free and the lead-based systems. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-10-03 15:13:24.791

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This thesis presents a study of three electrochemical methods applied to the fragmentation of proteins. Direct electrochemical oxidation at graphite electrodes, production of hydroxyl radicals on lead dioxide electrodes and electro-Fenton methods were each investigated as methods for fragmenting proteins. A key objective of this project was to achieve specific fragmentation, meaning that fragmentation would only occur at defined sites on each protein molecule and that this process may provide a new pathway to producing useful protein fragments. Protein fragments produced by electrochemical means were detected using mass spectroscopy and gel electrophoresis techniques. Direct electrochemical oxidation of the target proteins was studied at a graphite rod electrode in a solution containing acetonitrile, water and formic acid. β-lactoglobulin fragmentation was detected by mass spectroscopy, but fragmentation did not occur to an extent where fragments were observable by gel electrophoresis. It was evident that most of the electrolysis products appear to arise from non-cleavage oxidation reactions. The use of lead dioxide electrodes to generate hydroxyl radicals was thoroughly investigated in this work. For the first time, specific fragmentation of proteins has been achieved by direct electrochemical generation of hydroxyl radicals on the electrode surface. The pH and the chemical composition of the protein solutions were found have a strong influence on the extent of fragmentation. Electro-Fenton chemistry was conducted on a woven carbon fibre electrode. The electrode successfully reduced dissolved oxygen to produce hydrogen peroxide and regenerated Fe(II) from Fe(III). Cell conditions were optimized for applied current, method of oxygen delivery and cell division. The Fenton reaction between hydrogen peroxide and Fe(II) produced hydroxyl radicals that were able to specifically fragment proteins. It was not possible to increase the concentration of these protein fragments by increasing the hydrogen peroxide concentration, as the fragmentation products were also further fragmented. Electrochemical protein fragmentation was achieved in all three electrochemical systems, however the most promising results were achieved by electrochemical generation of hydroxyl radicals on a lead dioxide electrode. This work has the potential to become a fast and cost effective method for the fragmentation of proteins required for nutrition and medical purposes or for use in protein identification analysis with mass spectroscopy.

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A number of symmetric porphyrins containing both zinc(II) and lead(II) central metal ions have been prepared. Several routes to these compounds have been investigated and their merits evaluated. The conjugation of the chromophores has been extended by the inclusion of different <I>trans</I>- substituted arylethynyl substituents in the <I>meso</I>-position. An improved multigram method for the preparation of [bis-trimethylsilyethynylporphinato]zinc(II), which does not necessitate chromatographic purification, is described. The use of [5-triisopropylsilylethynylporphinato]zinc(II) for the preparation of donor/acceptor prophyrins via Sonogashira coupling, several of which were prepared, is also described. Investigations of the binding of 4(3<I>H</I>)pyrimidone with [5,5'-bis-[10,20-bis(3,5-di-<I>tert</I>-butylphenyl)-15-tri-iso-propylsilylethynyl-porphinyl]-1,3-butyn-1,4-diyl]dizinc(II) were made. The association constant was found to be 2500 ± 140 mol^-1 (ΔG = -4.6 Kcal/mol), significantly greater than that for 4(3<I>H</I>)pyrimidone alone (444 ± 5 mol^-1), as determined by NMR dilution experiments. The crystal structures of [5,15-bis(3,5-bis-<I>tert</I>-butylphenyl)porphinato]zinc(II), [5,15-bis-(3,5-di-<I>tert</I>-butylphenyl)-10,20-bis-triisopropylsilylethynylporphinato]lead(II), [5,10,15,20-<I>tetrakis</I>-triisopropylsilylethynylporphinato]lead(II), 5,15-bis-(3,5-bis-<I>tert</I>-butylphenyl)-10,20-bis-phenylethynylporphyrin, [5,15-bis-(3,5-bis-<I>tert</I>-butylphenyl)-10,20-bis-(3-hydroxy-3-methyl-butynyl)porphinato]zinc(II),5,10,15,20-<I>tetrakis</I>-triisopropylsilylethynylporphyrin and [5,15-bis-(3,5-bis-<I>tert</I>-butylphenyl)-10-(4-N, N-dimethylaminophenylethynyl)-20-triisopropylsilylethynylporphinato]zinc(II) are also described.

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As human populations grow worldwide, there is an increasing need to address the problems associated with the creation and disposal of wastes. Although a variety of recent technologies have been shown to be somewhat effective in the remediation of metal contaminated soils, e.g., chemical extraction and stabilization, they are often expensive and labor-intensive. Additionally, these technologies can impart detrimental effects on the chemical and physical properties of the soil under treatment. As an alternative, the less expensive, more environmentally benign use of green plants as tools for the remediation of contaminated soils (phytoremediation) has been studied in recent years.The reported research activities studied the ability of a variety of green plants to extract lead (Pb), cadmium (Ca) and barium (Ba) from metal contaminated soil. Additionally, the researcher studied the degree to which the addition of the synthetic chelate diethylenetriaminepentaacetate (DTPA) and dilute HNO3 affected: the phytoextraction of metals from contaminated soil; the translocation of these metals within study plants; and the effects that the treatments had on biomolecule production in Zea mays, Glycine max, Brassica juncea and Helianthus annuus. A growth chamber study was also conducted to determine if several species of green plants (Ipomoea leptophylla, Lycopersicon esculentum, Capsicum annuum and Tagetes minuta) were capable of hyperaccumulating any of the metals present in the contaminated soil. Additionally, a leachate study was performed to determine the effects that DTPA and HNO3 had on soil Pb mobility rates.Samples were analyzed for Pb, Ca and Ba using FAAS and the data were further analyzed to determine universal measures of variance. While no plants showed overall significant (p=0.05) differences with regard to both treatment and plant part, all species were capable of both accumulating and distributing Pb from the contaminated soil; no plants were able to extract Ba from the soil; some plants extracted trace amounts of Cd in various plant parts. Significant (p=0.05) differences were measured in chlorophyll a, chlorophyll b and carotenoid concentrations with regard to both plant and treatment. Results from the Pb mobility study showed significant (p=0.01) differences in Pb mobility with regard to both treatment and time. / Department of Natural Resources and Environmental Management

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No description available.