Nanometer thick layers of clay and polymer were formed on mica, silicon, and aluminum 2024-T3 alloy using alternating solutions of positively and negatively charged polymer and clay, respectively. Atomic force microscopy was used to observe the morphology of the composite films on mica and silicon. It was found that solution concentrations of clay above 0.02 weight percent lead to the uncontrolled deposition of clay platelets on the substrate's surface. By using solution concentrations of clay above 0.02 weight percent and ultrasonic agitation together it is possible to deposit a uniform monolayer of clay platelets on a mica substrate in £ 20 seconds. Ultrasonic agitation also produced crude patterns of montmorillonite platelets. Thin films of poly(diallydimethylammonium chloride) (PDDA) were made using concentrations ³ 2 weight percent of PDDA. It was found that the PDDA formed several unusual morphologies. Spherulites of PDDA were observed with AFM and the glass transition temperature of high molecular weight PDDA was measured using differential scanning calorimetry (DSC). Circular regions of positive charge were discovered on silicon wafers provided by three different sources. These areas of charge have never been reported in literature, but can easily be detected by placing wafers into solutions containing negatively or positively charged solutions of clay or polymer, respectively. The exact nature of these charged regions is unknown, but it is hypothesized that impurities on silicon wafers create the circular regions of positive charge. ISAM films made of a polyamide salt and a synthetic clay, Laponite RD®, demonstrated significant corrosion resistance on 2024-T3 Al alloys after 168 hours of salt spray testing. The ISAM films offered corrosion protection only if there was a significant layer of underlying surface oxide present, however. It was found that ISAM deposited films of polyarylic acid (PAA) and polyallylamine hydrochloride (PAH) may offer some corrosion resistance on 2024-T3 Al alloys, but these films' corrosion resistance is severely hampered by the presence of Cl- in the PAH solution. Funding from this project was gratefully received from the Materials Science and Engineering Department at Virginia Tech; Luna Innovations Inc; the American Chemical Society / Petroleum Research Fund #34412-G5 and the Environmental Protection Agency Contract #68-D-00-244. / Master of Science

This study developed a general framework that can be applied to integrating environmental sustainability aspects into economic development planning in the case of exploiting water resources through inter-basin water transfers (IBWT). Using the Lesotho Highlands Water Project (LHWP) between Lesotho and South Africa (SA), the study used the multi-country ecological social accounting matrix (MC-ESAM) for Lesotho and SA to integrate ecological implications of the LHWP with the economic benefits of the project. The study further used the developed MC-ESAM multipliers to analyse the impact of lost ecological services downstream the LHWP dams in Lesotho on the wellbeing of households directly affected by the project in Lesotho and the general economies of Lesotho and SA. The MC-ESAM multipliers were also used to analyse different policy scenarios aimed at compensating affected households in Lesotho for ecological losses. The results revealed that while the LHWP has significant direct and indirect benefits in terms of social and economic development in Lesotho and SA, the project has serious unitended impacts on ecological resources and services, with resultant deleterious wellbeing implications for populations residing within the reaches of the LHWP rivers and downstream the LHWP dams in Lesotho. The results from the MC-ESAM multiplier analysis indicated that not only the income of populations directly affected by the project in Lesotho is likely to fall, but also that of other households and social groups, as well as the general economies of Lesotho. Also, because of economic dependence of Lesotho on SA in terms of imports, SA will also loose. The policy simulation results showed that compensating the ecological losses would greatly improve the welfare of directly affected populations and the rest of Lesotho economy. The empirical analysis and policy simulations results showed relatively small impacts in general, but were significant for groups of people directly affected by the project in Lesotho. The study demonstrated the importance of integrating ecological consequences into impact assessment of IBWT before such transfers can be implemented to ensure Pareto optimality and of considering economy-wide impacts and multi-sector, multi-country linkages associated with IBWT for a holistic impact assessment of IBWT. / Thesis (PhD (Agricultural Economics))--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted