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The development of artificial metal-based catalytic systems for phosphate ester hydrolysis is the central focus of this work. Currently, significant efforts are concentrated in this field of research as phosphate esters are remarkably stable linkages and are found in the molecules of life DNA and RNA, as well as in toxic compounds, such as nerve agents, pesticides and herbicides. The thesis describes the design and synthesis of a series of N-functionalised azamacrocyclic ligands suitable for metal chelation. An efficient strategy is described, where an aminal precursor is used for the selective N-alkylation of a cyclen moiety, in order to obtain non-bridged and ethylene-bridged cyclen-based ligands. Thereafter, the synthesis of the tetraamine Co(III) and Zn(II) aqua-hydroxo complexes is detailed, followed by a study of the coordination chemistry of Co(III)-based cyclen complexes. Moreover, the redox behaviour of such complexes is investigated by means of cyclic voltammetry. The hydrolytic activity of these complexes towards phosphate ester substrates is then presented. The hydrolytic activity of the cyclen-based Co(III) complexes is shown to be extremely sensitive to modest changes in the ligand structures, even though they do not affect the coordination geometry. Cyclen-based Zn(II) complexes appear to have no appreciable activity towards hydrolysis of phosphate mono- and di-esters under the same experimental conditions. The effect of incorporating polymerisable tetraamine Co(III) complexes into the nanogels on their hydrolytic efficiency is also investigated using molecular imprinting technique. The design and synthesis of structurally similar tripodal 'click' ligands, suitable for the preparation of a range of d-block metal complexes is then presented. The coordination chemistry of the complexes of these structurally similar ligands is explored using a range of techniques including single crystal X-ray crystallography, EPR and UV-Vis spectroscopies and cyclic voltammetry. Due to their poor aqueous solubility various ways to improve this are also examined. Future developments of the metal-based catalysts are then discussed including key issues to be addressed to achieve their potential applications in biological systems.

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Lignocellulose is a promising and valuable alternative energy source. Native lignocellulosic biomass has limited accessibility to cellulase enzyme due to structural features; therefore, pretreatment is an essential prerequisite to make biomass accessible and reactive by altering its structural features. The effects of substrate concentration, addition of cellobiase, enzyme loading, and structural features on biomass digestibility were explored. The addition of supplemental cellobiase to the enzyme complex greatly increased the initial rate and ultimate extent of biomass hydrolysis by converting the strong inhibitor, cellobiose, to glucose. A low substrate concentration (10 g/L) was employed to prevent end-product inhibition by cellobiose and glucose. The rate and extent of biomass hydrolysis significantly depend on enzyme loading and structural features resulting from pretreatment, thus the hydrolysis and pretreatment processes are intimately coupled because of structural features. Model lignocelluloses with various structural features were hydrolyzed with a variety of cellulase loadings for 1, 6, and 72 h. Glucan, xylan, and total sugar conversions at 1, 6, and 72 h were linearly proportional to the logarithm of cellulase loadings from approximately 10% to 90% conversion, indicating that the simplified HCH-1 model is valid for predicting lignocellulose digestibility. Carbohydrate conversions at a given time versus the natural logarithm of cellulase loadings were plotted to obtain the slopes and intercepts which were correlated to structural features (lignin content, acetyl content, cellulose crystallinity, and carbohydrate content) by both parametric and nonparametric regression models. The predictive ability of the models was evaluated by a variety of biomass (corn stover, bagasse, and rice straw) treated with lime, dilute acid, ammonia fiber explosion (AFEX), and aqueous ammonia. The measured slopes, intercepts, and carbohydrate conversions at 1, 6, and 72 h were compared to the values predicted by the parametric and nonparametric models. The smaller mean square error (MSE) in the parametric models indicates more satisfactorily predictive ability than the nonparametric models. The agreement between the measured and predicted values shows that lignin content, acetyl content, and cellulose crystallinity are key factors that determine biomass digestibility, and that biomass digestibility can be predicted over a wide range of cellulase loadings using the simplified HCH-1 model.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 114-137.

Thesis (M.S.)--Brigham Young University. Dept. of Physiology and Developmental Biology, 2008. / Includes bibliographical references (p. 20-21).

The purpose of this work is to frame the main issues one must face in the design of a mobility control process using polyacrylamide and related acrylic polymers under hostile conditions. Proper preliminary lab evaluation techniques, chemical degradation and related calcium tolerance issues, thermal degradation, and economic optimization based upon injectivity are discussed. Emphasis is placed on stability under alkaline conditions, the use of sodium dithionite to prevent thermal degradation, and the beneficial use of in-situ hydrolysis to increase injectivity. Filtration properties are a focus of screening experiments, and though it often takes several days to achieve acceptable filter ratios in the lab, experience from two field observations indicate that even high molecular weight polymers have filtration ratios on the order of 1.2 or less before they are injected, so preparation procedures that do not result in this may not yield results that scale to the field. Chemical stability issues with acrylamide polymers are addressed in two parts, the first describing the kinetics of hydrolysis under neutral and alkaline conditions and the second estimating the calcium tolerance of aged polymers using industrial and lab produced analogues. Under alkaline conditions, hydrolysis is very rapid, even at low temperatures. Though aged copolymers of acrylamide (AM) and 2-acrylamide 2-methyl propane sulfonate (AMPS) exhibit similar calcium tolerances to similarly aged polyacrylamide (PAM), viscosity loss is much higher for the latter as this limit is approached. Thermal, or "oxidative" degradation, is examined using Pourbaix diagrams for iron to understand the commonly reported relationships between pH, Eh, and stability. The beneficial effects of sodium carbonate and sodium dithionite on polymer solutions as well as some inconsistencies in the literature point towards a catalytic role played by ppb level amounts of iron in oxidative degradation mechanisms. It is put forward that addition of sodium dithionite is a conservative approach to all acrylic-backboned polymer floods, and practical issues related to this are discussed. A simple analytical model is developed to take a brief look at economic optimization of polymer viscosity, and this is used to demonstrate the benefits of in-situ hydrolysis in alkaline or high-temperature floods. / text