The insecticide dichloro-diphenyl-trichloroethane (DDT) is widely used in indoor residual spraying (IRS) for malaria control owing to its longer residual efficacy compared to other World Health Organization (WHO) alternatives. It was envisaged that by investigating mechanisms of degradation of these alternative insecticides, a better understanding would be obtained on strategies of stabilising them and rendering their efficacy comparable with or better than DDT, hence providing less controversial and more acceptable and effective alternative insecticide formulations to DDT. This study sought to investigate the reasons behind the reported longer lasting behaviour of DDT by exposing all the WHO approved insecticides to high temperature, high humidity and ultra-violet light. Interactions between the insecticides and some mineral powders in the presence of an aqueous medium were also tested. Simple insecticidal paints were made using slurries of these mineral powders whilst some insecticides were dispersed into a conventional acrylic paint binder. These formulations were then spray painted on neat and manure coated mud plaques, representative of the material typically used in rural mud houses, at twice the upper limit of the WHO recommended dosage range. DDT was applied directly onto mud plaques at four times the WHO recommended concentration and on manure plaques at twice WHO recommended concentration. All plaques were subjected to accelerated ageing conditions of 40 °C and a relative humidity of 90%. In the accelerated ageing tests, Fourier transform infra-red (FTIR) interferograms showed that pyrethroids were the most stable insecticides compared to carbamates and DDT. High temperature oxidation, ultra violet light and humidity were ruled out as the cause of failure of the alternative insecticides. Gas chromatography (GC) interferograms showed that phosphogypsum stabilised the insecticides the most against alkaline degradation. Bioassay testing showed that the period of efficacy of these formulations was comparable to that of DDT sprayed at 4 times the upper limit of the WHO recommended dosage range. Bioassay testing also showed that these insecticidal “paint” formulations stabilised the insecticides on cattle manure coated surfaces as compared to DDT sprayed directly on similar surfaces. Bioassay experiments indicated that incorporating insecticides into a conventional paint binder or adsorbing them onto phosphogypsum provided effective life spans, under accelerated ageing conditions, comparable to or exceeding that of DDT directly applied to typical soil substrates. Best results were obtained with propoxur in standard acrylic emulsion paint. Similarly, insecticides adsorbed on phosphogypsum and sprayed on cattle manure coated surfaces provided superior lifespans compared with DDT sprayed directly on a similar surface. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

The modern painting process in automotive industry is complex and a lot of factors affect the result. The trial and error method is used today to control the quality and introduce new colours. This method takes a lot of time and does not show any clear numbers of how the process is affected by changing the parameters. During this thesis, we have investigated a delimited number of parameters. The work is based on experiments performed on samples that represents a flat surface of the cab, to reduce experimental costs. Our master thesis is done at Scania in Oskarshamn, where all the cabs for the European production is produced. The objectives with this thesis has been to explain how the process parameters of the robotic applicator affect the paint distribution, paint thickness and the colour of the top coat. We also optimised the process by finding which settings gives an even paint distribution, a correct thickness and an accepted colour of the top coat. We have been using Design of Experiments to achieve the goals of this study. Design of Experiments is a statistic method that is used to perform experiments effectively. It also shows the effect of changing the factors from a low to a high level. We have chosen to divide the workflow into three parts: screening, optimisation and confirmation. The experiments are performed during the daily production to replicate the real circumstances. The shape air, paint flow and high rotation is the most important parameters to control. Paint flow also seems to have a linear impact on the thickness of the top coat layer. The Shape air and the high rotation on the other hand mainly affect the distribution of the top coat layer. Different levels are needed for the shape air and high rotation depending on what paint flow is used. The optimal settings of the factors for our colour were found to be paint flow at 82 %, the shape air at 90 %, the high rotation at 90 % and high voltage at 100 %. The optimal settings give a result of 1,535 μm in spread and 40,08 μm in mean thickness. Our settings compared to today’s results contributes to a reduced paint consumption, better quality and therefore less rework.

Like every other poet, I’ve always been trying to write the poem living inside of me. The poem of myself. So many iterations of this very poem have come about because of my exploration of the greats and because of my exploration of self. The most predominant themes that come up in my thesis are my Cherokee heritage and culture, my family, and my chosen relationships. Interspersed are poems about hardships I, and others, have faced as women. The constant dilemma of womanhood is certainly exacerbated when “woman” is paired with “non-white.” Through my poems, I’ve tried to explore these themes as authentically and a transparently as possible. This means that occasionally I’ve expressed frustration and anger and fear. Please let this abstract serve as a content warning for mention of sexual assault and an eating disorder. The truth of poetry is that it is the place where we house our traumas, frustrations, and major questions. In this manuscript, I have housed many pieces of myself and I hope that the reader is willing to cry in the crevasses and delight in the peaks with me.

Water-borne latex coatings represent a safer, more user-friendly, and environmentally responsible alternative to solvent-borne coatings, and are growing in popularity each year. However, these coatings often exhibit unfavorable performance when exposed to water for extended periods of time. This prolonged exposure often results in water uptake, which may give rise to other detrimental effects such as a decrease in modulus, blushing or water-whitening, reduced serviceable life, and softening of the film. In this study, various polymer composition latex design spaces are studied to develop an understanding of how water uptake can be modulated and minimized using common synthetic approaches. Factors including monomer selection, particle size, polymer molecular weight, crosslinking density, surfactant choice and particle stabilization, processing variables and Tg are considered. In addition, some formulation modifications including PVC, film thickness, and choice of coalescent package are explored to gain a more comprehensive understanding of final product performance. In quantifying the total water uptake of the films, gravimetric analysis tends to be the preferred method employed in the coatings industry. However, other analytical approaches can be used to better understand the effect that water has on the properties of the film. These methods may include differential scanning calorimetry, electrochemical impedance spectroscopy, immersion testing using dynamic mechanical analysis, and others. In the work, it has been shown that interparticle crosslinking, surfactant, and monomer selection can have an extreme influence on the water uptake of free films. Film samples exhibit a range of water uptake values from nearly 200% to less than 5% over a one-week soak in deionized water. It is thought that the surfactant may provide hydrophilic channels that allow water to v penetrate the film and form heterogeneous domains within the coating. These domains then grow and scatter light, leading to water-whitening and an increase in mass when compared to the dry film. Utilizing monomers with differing relative solubilities in water, such as methyl methacrylate and styrene, further allow control of this effect. Interparticle crosslinking via keto-hydrazide crosslinking, which is achieved during the film formation process, can also prevent the formation and growth of these large water domains, thus resulting in better performing films.

Recent advancements in corrosion-resistance coating technology has reduce the use of environmentally harmful compounds such as Hexavalent Chromium by replacing Hexavalent Chromium in primers and topcoat. However, marking inks were neglected in the process. Products such as Enthone 50 series are still widely used, which contain compounds such as lead, hexavalent chromium, bisphenol A (BPA), Cadmium Sulfide, and more. Excluding catalyst compositions in Enthone, the chemicals in the ink alone contained three reproductive toxicant and numerous carcinogens. Therefore, it was essential to search and validate the performance of potential marking ink that would meet the standards in military applications. Eleven products were tested, and two products were recommended for use: Sherwin Williams MIL-PRF-22750 Type I and Union Ink Uniglaze. Both products contain at most one carcinogen ingredient and no reproductive toxicant. Both products passed MIL-STD 202G Method 215K solvent test, MIL-STD 202G Method 107G thermal shock test, MIL-STD-810G, Method 507.5 humidity test, cleaning system test, ASTM D3359, measure adhesion by tape test.

A new pressure-measurement technique which employs the tools of molecular spectroscopy has recently received considerable attention in the fluid mechanics community. Measurements are made via oxygen-sensitive molecules attached to the surface of interest as a coating, or paint. The pressure-sensitive-paint (PSP) technique is now commonly used in stationary wind-tunnel tests; this thesis presents the extension of the technique to advanced turbomachinery applications. New pressure- and temperature-sensitive paints (TSPs) have been developed for application to a state-of-the-art transonic compressor where pressures up to 2 atm and surface temperatures up to 140° C are expected for the first-stage rotor. PSP and TSP data has been acquired from the suction surface of the first-stage rotor of a transonic compressor operating at its peak-efficiency condition. The shock structure is clearly visible in the pressure image, and visual comparison to the corresponding computational fluid dynamics (CFD) prediction shows qualitative agreement to the PSP data. / Master of Science

In 21st century Scandinavia, the use of colored paint in the built environment has decreasedconsiderably. Instead, color changing LEDs can be found in many homes. In this thesis, an experimentwas set up to investigate how these two coloring methods differ and coincide with regards toemotional response and perception of materiality. Four cubicles, two painted and two colored bylight, were evaluated by ten participants. The painted cubicles were perceived as more material intheir appearance with regards to texture and color than their counterparts. A greater feeling ofnervousness, stress, and disorientation was felt in the light-colored cubicles as opposed to aheightened feeling of inspiration, excitement and calmness in the painted cubicles. Though it isimportant to remember the difference was not significant. In addition, preconceived connotations tothe color tone could be an influencing factor and so further studies on additional tones should beconducted. Lastly, benefits and drawbacks with the coloring methods were discussed.

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