No description available.

In the field of nuclear medicine, radioisotopes are used for applications such as diagnostic imag- ing, treatment, and equipment sterilization. The most commonly used radioisotope in medicine is technetium-99m (Tc-99m). It is used in 80% of all nuclear medicine procedures. Its parent isotope is molybdenum-99 (Mo-99). NRU, which is now closed, formerly produced 40% of the worlds demand for Mo-99. The production capacity of this reactor has been supplemented by a network of cyclotrons and a modified research reactor. This study aims to provide an alternative means of production for Mo-99, as well as other radioisotopes by modifying the center pin of a standard 37-element bundle of a CANDU reactor. The neutron transport code DRAGON, and the neutron diffusion code DONJON were used to model a CANDU-9 reactor. The lowest, median, and highest power channels were chosen as candi- dates for the modified bundles. It was found that the reactor parameters were altered by a negligible amount when any one channel was used to house the modified bundles. Significant quantities of the radioisotope lutetium-177 as well as the generating isotopes of the alpha-emitting radioisotopes lead- 212/bismuth-212, and radium-223 were produced. However, only minute amounts of molybdenum-99, and the generating isotope of bismuth-213 were produced. / Thesis / Master of Applied Science (MASc)

In light of the world‟s growing demand for energy that is environmentally friendly and sustainable, energy sources such as hydrogen have been considered potential contenders. Hydrogen, which can be used for energy storage, can be produced efficiently by the membrane based Hybrid Sulfur (HyS) thermo-chemical process consisting of a decomposition and an electrolysis step. During the HyS electrolysis step, SO2 and H2O are converted to H2 and H2SO4, which implies that the proton exchange membranes (PEMs) to be used for this process should have a high proton conductivity, limited SO2 cross-over and good H2SO4 stability. In order to find alternatives to the costly and high-temperature unstable Nafion®, the aim of this study was to evaluate the H2SO4 stability of various novel membranes. To structure the study, the novel PEM materials were grouped according to the PBI-type base component within the blend membranes, resulting in three groups comprising non-PBI based membranes, PBIOO based membranes and F6-PBI based membranes. Nafion®212 was included as reference PEM. By repeating the H2SO4 treatment with three different Nafion®212 samples, the obtained Nafion® data was also used to determine the experimental and analytical error margins for the study. The stability of all membranes was determined by submerging the membrane samples in 80 wt% H2SO4 at 80 °C for 120 hours. To determine the influence of the acid on the membranes, all samples were characterised before and after the H2SO4 treatment and compared in terms of their acid stability. Physical characterisation of the PEMs included the evaluation of weight and thickness changes, while IEC, SEM-EDX, FTIR and TGA were used to elucidate possible chemical changes due to the H2SO4 treatment. According to the Nafion®212 data, which had been obtained in triplicate for each of the analytical techniques, the experimental error of both the analytical and H2SO4 treatment remained below 10 %, except for the SEM-EDX sulfur-content where significantly larger errors were observed. In spite of the high error margins of the SEM-EDX data (S-content), its results, combined with the results from the other analytical techniques, resulted in a better understanding (both physical and chemical) of the effect the H2SO4 had on the membrane. This further facilitated the evaluation and comparison of the various blended PEM materials in terms of their H2SO4 stability, and the subsequent relation obtained between the observed stability and the chemical constitution and cross-linking of the membranes. After the 80 wt% H2SO4 treatment, significant weight losses were reported for the non-PBI based and PBIOO based membrane groups in comparison with the minimal changes noted for the F6-PBI based group and Nafion®212. Furthermore, significant thickness changes were reported for most of the PBIOO based membranes. The small weight and thickness changes observed for the F6-PBI confirmed the improved stability of this group of membranes in an H2SO4 environment, most likely due to the protective role of the partially fluorinated basic polymer and the known strength of the C-F bonds present. The results showed a clear correlation between the H2SO4 stability and the specific polymers present in the PEM blends investigated. Specific effects found included sulfonation, salt formation, hydrolysis and the accompanied dissolution of membrane fragments. Significant physical changes, for example ascribed to sulfonation of the concerned polymers, were supported by increased IEC measurements and peak intensities of the FTIR spectra, corresponding to the additional –SO3H groups present, while a variation in TGA signals served to further support the altered membrane composition and structure due to the H2SO4 treatment. In the case of dissolution, the corresponding chemical changes (analytical techniques) were supported by the decreased peak intensities of FTIR spectra, IEC measurements and TGA signals associated with degradation of the polymer backbone. It was shown that the stability of the blended membranes depended on the composition (blend components) of the membrane and the effective cross-linking (interaction) between the blend components. For all three groups examined, it became apparent that blend components sFS and sPSU were, for example, more stable than sPEEK and that ionical cross-linking seemed more effective than covalent cross-linking of blend components. When considering all membranes tested, the non-PBI based blend membranes consisting of (s)PSU and PFS copolymers in the presence of fluorinated cross-linkers and the PBIOO-sPSU blended membranes including most of the F6-PBI based membranes showed sufficient stability to be recommended for SO2 electrolysis. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

In light of the world‟s growing demand for energy that is environmentally friendly and sustainable, energy sources such as hydrogen have been considered potential contenders. Hydrogen, which can be used for energy storage, can be produced efficiently by the membrane based Hybrid Sulfur (HyS) thermo-chemical process consisting of a decomposition and an electrolysis step. During the HyS electrolysis step, SO2 and H2O are converted to H2 and H2SO4, which implies that the proton exchange membranes (PEMs) to be used for this process should have a high proton conductivity, limited SO2 cross-over and good H2SO4 stability. In order to find alternatives to the costly and high-temperature unstable Nafion®, the aim of this study was to evaluate the H2SO4 stability of various novel membranes. To structure the study, the novel PEM materials were grouped according to the PBI-type base component within the blend membranes, resulting in three groups comprising non-PBI based membranes, PBIOO based membranes and F6-PBI based membranes. Nafion®212 was included as reference PEM. By repeating the H2SO4 treatment with three different Nafion®212 samples, the obtained Nafion® data was also used to determine the experimental and analytical error margins for the study. The stability of all membranes was determined by submerging the membrane samples in 80 wt% H2SO4 at 80 °C for 120 hours. To determine the influence of the acid on the membranes, all samples were characterised before and after the H2SO4 treatment and compared in terms of their acid stability. Physical characterisation of the PEMs included the evaluation of weight and thickness changes, while IEC, SEM-EDX, FTIR and TGA were used to elucidate possible chemical changes due to the H2SO4 treatment. According to the Nafion®212 data, which had been obtained in triplicate for each of the analytical techniques, the experimental error of both the analytical and H2SO4 treatment remained below 10 %, except for the SEM-EDX sulfur-content where significantly larger errors were observed. In spite of the high error margins of the SEM-EDX data (S-content), its results, combined with the results from the other analytical techniques, resulted in a better understanding (both physical and chemical) of the effect the H2SO4 had on the membrane. This further facilitated the evaluation and comparison of the various blended PEM materials in terms of their H2SO4 stability, and the subsequent relation obtained between the observed stability and the chemical constitution and cross-linking of the membranes. After the 80 wt% H2SO4 treatment, significant weight losses were reported for the non-PBI based and PBIOO based membrane groups in comparison with the minimal changes noted for the F6-PBI based group and Nafion®212. Furthermore, significant thickness changes were reported for most of the PBIOO based membranes. The small weight and thickness changes observed for the F6-PBI confirmed the improved stability of this group of membranes in an H2SO4 environment, most likely due to the protective role of the partially fluorinated basic polymer and the known strength of the C-F bonds present. The results showed a clear correlation between the H2SO4 stability and the specific polymers present in the PEM blends investigated. Specific effects found included sulfonation, salt formation, hydrolysis and the accompanied dissolution of membrane fragments. Significant physical changes, for example ascribed to sulfonation of the concerned polymers, were supported by increased IEC measurements and peak intensities of the FTIR spectra, corresponding to the additional –SO3H groups present, while a variation in TGA signals served to further support the altered membrane composition and structure due to the H2SO4 treatment. In the case of dissolution, the corresponding chemical changes (analytical techniques) were supported by the decreased peak intensities of FTIR spectra, IEC measurements and TGA signals associated with degradation of the polymer backbone. It was shown that the stability of the blended membranes depended on the composition (blend components) of the membrane and the effective cross-linking (interaction) between the blend components. For all three groups examined, it became apparent that blend components sFS and sPSU were, for example, more stable than sPEEK and that ionical cross-linking seemed more effective than covalent cross-linking of blend components. When considering all membranes tested, the non-PBI based blend membranes consisting of (s)PSU and PFS copolymers in the presence of fluorinated cross-linkers and the PBIOO-sPSU blended membranes including most of the F6-PBI based membranes showed sufficient stability to be recommended for SO2 electrolysis. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

No description available.

Despite the ongoing political debate regarding the legality of medical marijuana, clinical investigations of the therapeutic use of cannabinoids are now more prevalent than at any time in history. Cannabinoids have been shown to have analgesic, anti-spasmodic, anticonvulsant, anti-tremor, anti-psychotic, anti-inflammatory, anti-oxidant, anti-emetic and appetite-stimulant properties. There are mainly two well-known cannabinoid receptors, CB1 and CB2, located in the central (CB1) and peripheral (CB2) nervous systems as well as the immune system. More recently, endocannabinoids (ligands) and their receptors have also been found in the skeleton which appear as the main body system and physiologically regulated by CB2. This study aimed to examine the effect of both CB1 and CB2 receptor stimulation on wound closure response of MG-63 osteoblast bone cell monolayers using different treatments with cannabinoid such as Winn55,212-2, URB602 and HU308. Also, cell adhesion, cell proliferation and cell length was investigated. The study also aimed to examine the effect of HU308 treatments in combination with TGF-β3 (transforming growth factor beta -3) on wound healing, cell adhesion and extracellular matrix up regulation (collagen type I, fibronectin and protien S-100A6) as well as other biological factors such as secretion of matrix metalloproteinase (MMP-2) and nitric oxide (NO). Finally, this study investigated HU308/TGF-β3 combination treatment on the regulation of extracellular matrix (collagen type I, fibronectin and protien S-100A6) in a 3D multilayer system of MG-63 osteoblast bone cells. Wound healing assays of MG-63 monolayers revealed accelerated wound repair as well as increased cell proliferation mainly regulated through CB2 receptors, and that treatments with HU308 and HU308/TGF-β3 achieved minimum closure timings compared with control groups (P<0.05). Our finding suggested that proliferation rate with 500nM HU308 was significantly higher than control and TGF-β3/HU308 combination groups (P<0.05). Interestingly, percentage of wound remained open after 15 hours for combination groups was 17.6%±1.32 whereas treatment with 500nM HU308 had 20%±2.25 indicating that the combination groups took the lead throughout wound healing. It was also observed that bridge formation in all treatment groups was taking place between 15 to 20 hour periods whereas within control treatments bridge formation started to take place after 25 hours. Cell surface attachment was examined via the trypsinization assay in which the time taken to trypsinize cells from the surface provided a means of assessing the strength of attachment. The results indicated that higher concentrations of HU308 (2μM), induced significant force of cell attachment compared with control and concentrations of 500nM and 1μM (P<0.05). However, groups treated with TGF-β3 and combination HU308/TGF-β3 indicated reduced cell surface attachment compared with control groups, indicating enhanced cell migration. Immunofluorescence staining as well as Elisa based semi-quantification technique indicated that both collagen type I and fibronectin were unregulated using higher concentrations of HU308 with decreased cell proliferation compared to lower concentrations. Nevertheless, protein S-100A6 was up-regulated in treatments with HU308, TGF-β3 and their combination HU308/TGF-β3 (P<0.05), indicating the positive role of these treatments in promoting cell differentiation. MMP-2 levels in the current study were also shown to be concentration-dependent, i.e. higher concentrations of HU308 significantly reduced MMP-2 secretion leading to decreased cell migration, while HU308/TGF-β3 combination treatment increased MMP-2 levels, indicating an increase in cell migration. The current study also examined levels of nitric oxide synthesis in relation to different treatments with HU308, TGF-β3 and HU308/TGF-β3 combination. It was found that nitric oxide up-regulation influences rate of MG-63 osteoblast wound healing in a concentration dependent manner. Lastly, UpCell culture dishes proved to have efficacy in obtaining a multilayer model of MG-63 osteoblast system in-vitro through changes in cell morphology. It was also found that treatments with HU308, TGF-β3 and HU308/TGF-β3 combination influenced collagen type I, fibronecton and protein S-100A6 secretion. These findings supported the earlier Elisa based semi-quantification results obtained for monolayer cultures.

Due to the conditions peculiar to underwater, distinctive approaches are required to solve the navigation and path planning problem of an unmanned underwater vehicle (UUV). In this study, first of all, a detailed 6 degrees-of-freedom (DOF) mathematical model is formed, including the coupled non-linear forces and moments acting on an underwater vehicle. The hydrodynamic coefficients which correspond to the geometry of the vehicle which the model is based on are calculated using the strip theory. After the mathematical model is obtained, by applying appropriate linearization on the model, &ldquo / Linear Quadratic Regulator (LQR)&rdquo / control method is implemented to govern the surge, heave, pitch and yaw motions of the underwater vehicle. Path planning algorithm of the vehicle is based on tracking the waypoints. Permutation of the waypoints is obtained by solving the &ldquo / Travelling Salesman Problem (TSP)&rdquo / via genetic algorithm. Linked with that, &ldquo / Rapidly-Exploring Random Trees (RRT)&rdquo / algorithm is introduced into the path planning algorithm to avoid collisions in environments with obstacles. Underwater navigation solution is based on the &ldquo / Inertial Navigation System (INS)&rdquo / outputs, located on the vehicle. To correct the long-term drift of the inertial solution, &ldquo / Kalman Filter&rdquo / based integration algorithm is used and external aids such as &ldquo / Global Navigation Satellite System (GNSS)&rdquo / , &ldquo / Ultra-Short Baseline (USBL)&rdquo / acoustic navigation system and attitude sensors have been utilized. The control method, path planning and navigation algorithms used in this study are verified by simulation results.

A fuzzy logic control algorithm for self parking of a model car has been developed and an embedded controller hardware has been designed, manufactured and programmed to control parking maneuvers of a model car within the scope of this thesis study. The model car chassis consists of a DC motor actuated traction system and a servomotor actuated steering mechanism. Position data and parking place data is obtained by a sensory system. A stepper motor driven rotary table is designed and assembled to the model car chassis for positioning of the sensory system. The controller hardware includes all the required peripherals for interfacing to the motors and sensory system. A visual computer program running in PC environment is developed in order to simulate the control characteristics of the fuzzy logic algorithm. The program allows the user to generate fuzzy sets and fuzzy set members and allows the user to define membership functions and fuzzy rules. Once an appropriate control characteristic is obtained, all the parameters can be exported to a file in order to be downloaded to the controller.

In addition to general knowledge on the official curriculum subjects, including the English language, schools convey multiple cultural and ideological meanings, playing a significant role in the processes of socialization and cultural reproduction. The function of school textbooks as powerful agents of socialization is realized through the texts and visuals in the content. Locally issued ELT materials, written in English by local authors, comprise a combination of local and foreign social meanings. Positive social change may be initiated by constant revision of cultural and ideological implications in educational media and subsequent exclusion of integrated biased meanings and linguistic forms reinforcing social inequities. This research study deals with gender representations and gender discriminatory meanings in ELT textbooks. It focuses on the ways gender-related social inequalities are reflected in texts and illustrations in two ELT series published by the Turkish Ministry of National Education and the Iranian Ministry of Education. Critical discourse analysis was chosen for investigation of gender issues integrated in the content of the textbooks. The study examined representations of female and male characters at code level in the pronoun and noun systems, at sentence level in reading passages and dialogues, and in visuals. The study revealed imbalance in representations of woman and man, and gender-related stereotypes in all examined categories of both ELT series. In both Turkish and Iranian textbook sets, traditional female and male roles depicting women as mothers and housewives and men as breadwinners were emphasized more than modern ones sustaining gender egalitarianism in public and family spheres. In contrast to women, men took active parts in all essential social fields, and bigger numbers of males than females were involved in texts and illustrations. Authors&rsquo / gender did not have a big influence on the results obtained by the current research. It was suggested that gender-related ideologies and stereotypes are shared, supported, and unconsciously reproduced by both women and men in a society.

In this thesis, the integration of a MEMS based inertial measurement unit and a three axis solid state magnetometer are studied. It is a fact that unaided inertial navigation systems, especially low cost MEMS based navigation systems have a divergent behavior. Nowadays, many navigation systems use GPS aiding to improve the performance, but GPS may not be applicable in some cases. Also, GPS provides the position and velocity reference whereas the attitude information is extracted through estimation filters. An alternative reference source is a three axis magnetometer, which provides direct attitude measurements. In this study, error propagation equations of an inertial navigation system are derived / measurement equations of magnetometer for Kalman filtering are developed / the unique method to self align the MEMS navigation system is developed. In the motion estimation, the performance of the developed algorithms are compared using a GPS aided system and magnetometer aided system. Some experiments are conducted for self alignment algorithms.