An experimental research was performed to study the effects of surface roughness on the characteristics of separated and reattached turbulent flows in an open channel. A backward facing step was used to induce flow separation. The rough surfaces comprised wire mesh grit-80 and sand grains of average diameter 1.5 mm. In each experiment, the Reynolds number based on the step height and freestream velocity of approach flow was fixed at 3240 and the Reynolds number based on the approach flow depth and freestream velocity was kept constant at 25130. Particle image velocimetry (PIV) technique was used to measure the flow velocity. The results showed that roughness effects on the mean and turbulent quantities are evident only in the recovery region. Moreover, roughness effects on the flow dynamics are dependent on the specific roughness element.

5-Fluorouracil (5FU) is a pyrimidine analogue, indicated for the therapy of proliferative skin diseases such as actinic keratosis (AK), superficial basal cell carcinoma and psoriasis. It has also been used for the treatment of solid tumours like colorectal, breast and liver carcinomas for nearly 40 years. Although 5FU has always been administered parenterally and orally, metabolism is rapid and absorption is erratic. Several severe side-effects are also commonly associated with 5FU therapy, including myelosuppression, hand-foot syndrome and gastrointestinal effects. Seeing that 5FU is an important part of the treatment of several malignant and pre-malignant disorders, it would be advantageous to find a delivery route and delivery system that negate absorption and metabolic variation and decrease side-effects. The transdermal route provides a promising alternative to the above-mentioned conventional delivery routes, solving most of the problems associated with parenteral and oral administration. That being said, the formidable barrier situated in the skin is not easily breached. The stratum corneum, the outermost skin layer, is mostly lipophilic in nature, preventing hydrophilic molecules such as 5FU from entering. 5FU-containing creams and lotions are currently commercially available, but absorption is still very limited. The transdermal absorption from these formulations has been compared to that obtained with the use of new transdermal delivery vehicles, with the newer formulations proving to be promising. It was decided to entrap 5FU in a novel therapeutic system, in the form of the Pheroid™ system, to increase its transdermal penetration. Pheroid™ vesicles are stable spherical structures in a unique, emulsion-like formulation, and fall in the submicron range. The main components of the Pheroid™ system are the ethyl esters of the essential fatty acids linoleic acid and linolenic acid, as well as the cys-form of oleic acid, and water. The formulation is saturated with nitrous oxide (N20). Although Pheroid™ vesicles may resemble other lipid-based vehicles, such as liposomes and micro-emulsions, they are unique in the sense that they have inherent therapeutic qualities as well. The Pheroid™ formulation can be specifically manipulated to yield different types of vesicles, ensuring a fast transport rate, high entrapment efficiency, rapid delivery and stability of the delivery system for a specific drug. In this study, 5FU was entrapped in the Pheroid™ formulation. Transdermal permeation studies were then performed to evaluate the influence of this delivery system on the transdermal flux of 5FU. Vertical Franz diffusion cells were utilised to determine the transdermal penetration of 5FU. Only Caucasian female abdominal skin was used to minimise physiological variables. Diffusion studies were done over 12 hour periods, with the entire receptor phase being withdrawn at predetermined intervals. Samples were analysed using high performance liquid chromatography (HPLC), after which the cumulative concentration of active was plotted against time. The linear portion of this graph represents the flux of 5FU through the skin. It was found that there were differences in the results between formulations containing 5FU in a phosphate buffer solution (PBS)-based Pheroid™ and water-based Pheroid™, though the difference was not statistically significant. The 0.5 % 5FU in water-based Pheroid™ resulted in a significantly bigger yield than the control (1 % 5FU in water) as well as a significant difference to the 1 % 5FU in PBS-based Pheroid™ formulation. In general the water-based Pheroid™ formulations had greater average cumulative concentrations, yields and fluxes than the other formulations. The fluxes obtained with the water-based Pheroid™ formulations also correlated well with a previous study done by Kilian (2004). Thus it can be concluded that the Pheroid™ therapeutic delivery system enhances the transdermal penetration of 5FU. Water-based Pheroid™ formulations proved to be more effective than PBS-based Pheroid™ formulations. It can also be concluded that a 0.5 % 5FU in water-based Pheroid™ formulation can be used instead of a 1 % formulation, because there were no statistically significant differences between the two formulations. This would be advantageous - patient compliance can be enhanced because of a more tolerable formulation with fewer side effects, while manufacturing cost is lowered by using a lower concentration of active. It is recommended that some aspects of the study be investigated further to optimise the transdermal delivery of 5FU using the Pheroid™ therapeutic system. These aspects include optimising the composition of the Pheroid formulation, investigating the entrapment process of 5FU within Pheroid™ spheres, the influence of PBS and water as basis of the Pheroid™ formulation and the amount of 5FU remaining in the epidermis after the 12 hour period of the diffusion study. Keywords: 5-Fluorouracil, Franz diffusion cell, Heat separated epidermis, Skin penetration, Transdermal, Drug delivery system, Pheroid™ / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2008.

CADSYN (Computer Aided Design SYNthesis) is a visual, interactive computer program working under Computer Aided Design (CAD) enviroment, which accomplishes the synthesis and analysis of planar four-bar mechanisms. The synthesis tasks are motion generation, path generation and function generation. During synthesis, the dyadic approach is utilized which introduces vector pairs and complex number algebra to model the motion. The possible solutions can be limited for link dimensions, the center circle point curves within a certain region, transmission angle characteristics, branch and order defects. The designed mechanism can be analyzed for velocity, acceleration and transmission angle and any of the data can be exported to Excel&reg / for further analysis. The software is designed to provide the user maximum feasible number of solutions. In four multiply separated position synthesis, if there is flexibility in the value(s) of one or any number of input parameter(s), designer can obtain different Burmester curves by changing those parameter(s). Designer can also simulate the kinematics of the mechanism by using drawing functions that are available from the CAD iv enviroment at any time. Drawing parts in the design plane can be attached to any link of the mechanism and can be simulated throughout the motion as part of the link it is attached. As a whole, this computer program is designed to satisfy the needs of mechanism designers while working in CAD enviroment.

De nouvelles connaissances sur les écoulements autour des véhicules automobiles doivent aujourd'hui être apportées pour envisager une amélioration de leurs performances aérodynamiques. Ce travail de thèse repose sur des études expérimentales, réalisées en soufflerie, permettant l'analyse et la compréhension des mécanismes physiques associés aux écoulements décollés tridimensionnels et instationnaires se développant à l'arrière des véhicules automobiles. Il se concentre plus particulièrement sur la géométrie générique du corps de Ahmed permettant de reproduire les écoulements à l'arrière de véhicule de type bicorps (lunette arrière et culot). L'étude compare deux maquettes de géométrie différente dont l'une permet d'obtenir une zone de recirculation tridimensionnelle sur la lunette arrière et l'autre de conserver l'écoulement attaché. L'analyse et la comparaison des topologies moyennes des écoulements permettent d'évaluer les interactions entre la recirculation 3D et les autres structures en présence. On montre plus particulièrement que l'absence du décollement sur la lunette arrière modifie la topologie de l'écoulement à l'arrière du culot avec une réduction de traînée de l'ordre de 10%. Les résultats montrent que les effets de la recirculation ne sont pas assez importants pour modifier la position des structures tourbillonnaires longitudinales se développant sur les arêtes latérales de la lunette, mais modifient légèrement leur intensité. L'analyse spectrale des fluctuations de vitesse et de pression indique que la recirculation est le siège d'activités instationnaires pseudopériodiques. La Décomposition Orthogonale Propre des champs de vitesse et de pression montre finalement que ces activités sont associées à un mécanisme de battement de la recirculation passant d'une configuration décollée à une configuration attachée et à une émission de structures tourbillonnaires formées par la couche cisaillée de la recirculation. / More and more knowledge related to flows behind road vehicles must be provided to improve their aerodynamic performances. This PhD thesis deals with experimental studies carried out in a wind tunnel, and enables analysis and understanding of physical mechanisms related to three-dimensionnal and unsteady separated flows that develop behind road vehicles. More specifically, it focuses on the generic model of Ahmed body that recreates flows behind common fastback cars (rear window and rear part). This study compares two models with different shape, the first one having a sharped edge between the roof and the rear window enabling the development of a separated region, and the second one having a rounded edge preventing separation. Analysis and understanding of the time averaged topology of both flow configurations are performed to characterize interactions between the three-dimensionnal separation and the other structures. More specifically, it is observed that suppressing separated region over the rear window changes the flow topology behind the rear base with a drag reduction of approximately 10%. Results show that the influence of the separated region is not strong enough to modify the location of the longitudinal vortical structures, which develop at each side of the model, but is strong enough to slightly modify their intensity. Spectral analysis of the velocity and pressure fluctuations indicates that the separated region is characterized by pseudo-periodic unsteady activities. Proper Orthogonal Decomposition of instantaneous velocity and pressure fields shows that these activities are respectively related to a flapping mechanism of the separated zone moving between a shrinked state and an enlarged state, and a large scale vortices emmission resulting from the shear layer of the separated region.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The industrial processing of fish fillets generates large amount of waste that can cause serious environmental problems due to improper disposal. However, after filleting, muscles of good quality are found in the carcass, which can be used for human consumption. An alternative is the production of mechanically separated meat (MSM) or mincend fish for use in the processing ham-like products. In this context, in order to facilitate the use of co-products from fish industry, and increase the nutritional value of processed products, a ham-like product was prepared with different levels of mincend catfish (Rhamdia quelen). However, as the MSM of fish is highly perishable, it was first studied the antioxidant activit of different concentrations of phytic acid on fish mincend and fillets. Concentrations of 0,025% and 0,05% of phytic acid were tested, comparing them to the effect of 0,05% sodium erythorbate. Results demonstrate better antioxidant potential of phytic acid in a concentration of 0,05%. Having defined this concentration, hams were prepared with levels of 25, 50 and 75% minced catfish treated with 0,05% phytic acid in order to evaluate the effect of adding different amounts of mincend fish treated with natural antioxidant attributes on chemical composition, color and instrumental texture as well as sensory characteristics in ham-like products, was elaborated based hams with levels 25, 50 and 75% mincend catfish treated with 0,05% phytic acid. Adding minced fish in different concentrations to hams preparation influenced on the centesimal composition of each formulation. Moisture content was significantly affected. The 25% minced fish formulation was the only one which did not differ from the control. Moisture decreased as minced fish content increased. Regarding ash, the formulation containing 50% minced fish was the only one which showed significant difference while the control did not differ from the ones containing minced fish. Protein levels did not differ significantly among formulations. With exception of the formulation with 50% mincend of red color intensity decreased with increasing content of mincend. The lightness was not significantly different at the end of the period in all formulations and yellow color after sixty days, the formulations with the addition of mincend had higher intensity as the content. Texture analysis showed significant difference among formulations only for the variable thoughness, showing that by increasing the amount of minced fish content, the product becomes less tough. Sensory analysis did not show significant difference for variables of color and appearance. As to color, the increase of minced fish content decreased preference. The most accepted flavor was the control formulation. All formulations showed significant difference in texture. For a purchase attitude, the best values were attributed to the control formulation. Prices decreased according to the increase of minced fish content. The final product oxidation and pH were assessed for sixty days and showed that the use of phytic acid in ham-like cooked products is more efficient than sodium erythorbate. Based on these results, it is concluded that producing ham by replacing part of pork meat with minced fish containing phytic acid is viable because it presents characteristics for human consumption. / O processamento industrial de filés de pescados gera grande quantidade de resíduos que pode causar sérios problemas ambientais pelo descarte inadequado. Entretanto, na carcaça, após a filetagem, encontram-se músculos de boa qualidade que podem ser utilizados para a alimentação humana. Uma alternativa é a fabricação de carne mecanicamente separada (CMS) ou polpa de pescado para uso no processamento de produtos, como por exemplo, os embutidos. Neste contexto, a fim de viabilizar o aproveitamento de co-produtos da indústria de pescados, e aumentar o valor nutricional de produtos processado, elaborou-se embutido cárneo com diferente teores de polpa de jundiá (Rhamdia quelen). Contudo, visto que a CMS de pescado é altamente deteriorável, estudou-se primeiro a ação antioxidante de diferentes concentrações de ácido fítico sobre filés e polpa do pescado. Foram testadas concentrações de 0,025% e 0,05% de ácido fítico, comparando-as ao efeito do eritorbato de sódio 0,05%. Os resultados demonstram melhor potencial antioxidante do ácido fítico na concentração de 0,05%. Definida essa concentração, com o objetivo de avaliar o efeito da adição de diferentes teores de polpa de pescado tratada com antioxidante natural sobre atributos de composição química, cor e textura instrumental e características sensoriais em embutidos, elaborou-se apresuntados com teores 25, 50, e 75% de polpa de jundiá tratada com ácido fítico 0,05%. A adição de polpa de pescado em diferentes proporções as formulações dos apresuntados exerceu influência sobre a composição centesimal de cada uma. A umidade foi afetada significativamente, apenas a formulação com 25% de polpa não diferiu da controle. Quanto maior o teor de polpa, menor a umidade. Quanto as cinzas, entre as formulações com adição de polpa, apenas a com 50% apresentou diferença significativa e a controle não diferiu das que contém polpa. O teor de proteína não apresentou diferença significativa entre as formulações. Com exceção da formulação com 50% de polpa a intensidade de cor vermelha diminuiu a conforme o aumento do teor de polpa. A luminosidade não apresentou diferença significativa ao final do período em todas as formulações e na cor amarela, após sessenta dias, as formulações com adição de polpa apresentaram maior intensidade conforme o teor. A análise de textura apresentou diferença significativa entre as formulações apenas para a variável dureza, demonstrando que o aumento do teor de polpa torna o produto menos duro. A análise sensorial não demonstrou diferença significativa para as variáveis de aparência e cor. Quanto ao odor, a preferência diminuiu com o aumento de polpa. O sabor mais aceito foi o da formulação controle. Na textura todas as formulações apresentaram diferença significativa. Para atitude de compra, os melhores valores foram atribuídos a formulação controle, com decréscimo conforme o aumento do teor de polpa. A oxidação e o pH do produto acabado foram avaliados ao longo do período de sessenta dias e demonstraram que a utilização do ácido fítico em embutidos cárneos curados cozidos tipo apresuntado é mais eficaz que o eritorbato de sódio. A partir destes resultados pode-se concluir que a fabricação de apresuntado com substituição de parte da carne suína por polpa de pescado adicionada de ácido fítico é viável por apresentar características aceitáveis ao consumo.

Master of Science / Food Science Institute / Elizabeth A. Boyle / Pork preblends held for 0, 4 or 7 d were formulated into smoked sausages and analyzed for cook yield, instrumental external color, pH, salt content, proximate analysis, Warner-Bratzler shear force (WBSF), thiobarbituric acid reactive substances (TBARS), sensory analysis and purge percentage during 0, 110, 131 and 160 d display at an average 2.65 °C under fluorescent lighting. One preblend × day of display interaction was found for b* values. On display d 0, preblend d 7 was more yellow (P < 0.05) than preblend d 0 and 4; however, no differences (P > 0.05) were found for any preblends on d 110 or 160. On display d 131, preblend d 0 was more (P < 0.05) yellow than preblend d 4 but similar (P > 0.05) to preblend d 7. There was no preblend effect (P > 0.05) on any of the other attributes measured. Display day did not affect (P > 0.05) purge, pH, proximate analysis, WBSF, juiciness, saltiness or off-flavor. For color, a* and saturation index values decreased (P < 0.05) and L* increased (P < 0.05) between d 0 and 110 as well as d 110 and 131, while L*, a*, a*/b* ratio and saturation index values were similar (P > 0.05) from d 131 to 160. Hue angle value decreased from d 0 to 110 but was similar for the remaining display. A reduction (P < 0.05) in a*/b* ratio was shown from d 0 and 110 (average 0.85) to d 131 and 160 (average 0.78). There was a reduction in salt content by 0.43% and an increase in TBARS values by 0.46 mg malonaldehyde/100 g sample from d 0 compared to d 110, 131 and 160 (P < 0.05). Inconsistent differences were found for sensory panel traits bite and flavor intensity and a reduction in mouthfeel coating was found from d 0, 110 and 131 compared to 160 (P < 0.05). Therefore, preblending could be implemented without any detrimental outcome on quality or sensory attributes of skinless smoked sausage; however, as day of display increases product may become lighter, less red and more oxidized.

abstract: As sunlight is an ideal source of energy on a global scale, there are several approaches being developed to harvest it and convert it to a form that can be used. One of these is though mimicking the processes in natural photosynthesis. Artificial photosynthetic systems include dye sensitized solar cells for the conversion of sunlight to electricity, and photoelectrosynthetic cells which use sunlight to drive water oxidation and hydrogen production to convert sunlight to energy stored in fuel. Both of these approaches include the process of the conversion of light energy into chemical potential in the form of a charge-separated state via molecular compounds. Porphyrins are commonly used as sensitizers as they have well suited properties for these applications. A high potential porphyrin with four nitrile groups at the beta positions, a β-cyanoporphyrin (CyP), was investigated and found to be an excellent electron acceptor, as well as have the necessary properties to be used as a sensitizer for photoelectrosynthetic cells for water oxidation. A new synthetic method was developed which allowed for the CyP to be used in a number of studies in artificial photosynthetic systems. This dissertation reports the theories behind, and the results of four studies utilizing a CyP for the first time; as a sensitizer in a DSSC for an investigation of its use in light driven water oxidation photoelectrosynthetic cells, as an electron acceptor in a proton coupled electron transfer system, in a carotene-CyP dyad to study energy and electron transfer processes between these moieties, and in a molecular triad to study a unique electron transfer process from a C60 radical anion to the CyP. It has been found that CyPs can be used as powerful electron acceptors in molecular systems to provide a large driving force for electron transfer that can aid in the process of the conversion of light to electrochemical potential. The results from these studies have led to a better understanding of the properties of CyPs, and have provided new insight into several electron transfer reactions. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2015

The main aim with this thesis has been to understand how the resilience process could be enhanced for South Sudanese unaccompanied and separated children, USC, resettling in Nairobi, Kenya. The aim has further been to provide primary empirical data in order to bridge the gap on resilience research specifically related to this target group, within a non-western refugee context. The research has been carried out using a single case study design, with qualitative methods including an extensive literature review, and semi-structured interviews, as well as a questionnaire for qualitative purpose with 16 South Sudanese youth, arriving in Kenya unaccompanied or separated. Within this thesis, the concept of resilience has been approached from mainly a childhood perspective, focusing on research from the field of child psychology. As a complement, one specific model from the salutogenic research field on health promotion has also been used.   Through the case study, a variety of internal and external protective factors were identified, that could enhance the resilience process for South Sudanese USC. The most occurring were: a belief in God; focus, hard work and discipline; the desire to help family and people in need of support; education; support from others; and to understand and accept the new culture. In addition, the senses of meaningfulness, comprehensibility and manageability worked as important tools to further understand the protective factors that had enhanced resilience for the South Sudanese participants. The findings of this research have also included risk and vulnerability factors that could challenge the resilience process for the target group, including severe human suffering and stressful events; violence; lack of basic needs; loss of family and relatives; lack of mentor/advisor; and separation from family. The thesis ends with providing practical recommendations for humanitarian and development actors on how they best can support South Sudanese USC in the East Africa region.

Steel is a material commonly used in various constructions such as high-rise buildings, sport arenas, ships etc. Steel is a versatile building material due to its isotropic characteristics, e.g. both high tensile- and compressive strength. This allows steel to be formed into open section profiles which reduces material usage but simultaneously allows the tensile- and compressive stress resistance to be high in directions were loads are applied. Although steel has a high stress resistance its sensitivity to fire is larger than other building materials due to its high thermal conductivity. The strength of the material is reduced at higher temperatures and thereby makes the dimensioning of beams in fire cases vital in fire safety design of structural elements. An aspect to consider when dimensioning open section building elements in steel is the shadow effect. The shadow effect is the result of the open cross-section geometrical shape of beams and columns, e.g. H-profiles. The interior of the profile is screened from thermal radiation caused by fire which makes the characteristics of the thermal exposure different from closed cross-section profiles. A common way to estimate the temperatures of steel after a certain time of fire exposure is to use numerical calculations described in Eurocode. In these calculations the shadow effect is applied as a reduction of the total heat exchange, i.e. both convection and thermal radiation, from the fire exposure. A more realistic approach is to separate these boundary conditions and treat them as independent quantities. Wickström (2001) argues that a void is created within the flanges and that reduction factor thereby only should be applied to the radiative part of the total heat exchange, acting as a reduction of surface emissivity within the profile. This, since the convection is not affected by the shadow effect. Wickströms (2001) suggestion of application has been investigated in this thesis and has showed a better correlation than the approach suggested in Eurocode when compared to experimental tests. Shadow effects calculated on the premises of separated boundary conditions for the total heat exchange has of yet only been investigated in detail with TASEF+-simulations, but these simulations predicts steel temperatures with satisfactory results. It is possible to reproduce a similar setup in the program COMSOL Multiphysics in two-dimensional simulations, and further three-dimensional simulations. This possibility has been investigated in this thesis. COMSOL Multiphysics has proven to be an adequate tool when it comes to simulate fire exposure on slender steel beam with shadow effects considered. Both three- and two-dimensional models produced simulation results correlating well to simulations conducted in TASEF. Additionally, adequate correlations with experimental tests were obtained for COMSOL Multiphysics as well. Further work regarding fire simulations with the utilisation of COMSOL Multiphysics is thereby suggested.

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