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Development of the Zirconium-based metal- organic framework UiO-66 for Adsorption-mediated electrochemical sensing of organonitrogen compounds in fuels
Get PDFThe combustion of fuel which contains organonitrogen compounds has led to an increase in atmospheric and environmental levels of nitrogen oxides which are responsible for several environmental, ecological, and human health problems. With increasingly strict environmental regulations and deleterious effects of the nitrogen-containing compounds in fuels, there is a strong need for the removal and detection of nitrogen-containing compounds in fuels to produce fuels with lower levels of nitrogen compounds. The Environmental Protection Agency (EPA) mandated nitrogen content in fossil fuels to be about less than 1 wt%. The existing analytical techniques used for the quantification of nitrogen-containing compounds in fuels include GC-MS, GC-AED, and spectrophotometry. Despite being sensitive and specific, these methods require expensive equipment, highly trained personnel, and time-consuming pre-treatment methods to avoid interferences from similar compounds, and they suffer from analyte loss and inadequate results. Thus, they can only be carried out in the off-site laboratories, hindering them from rapid on-site screening. The metal-organic framework (MOF) UiO-66-NH2 and its composites UiO-66-NH2/GA, and UiO- 66-NH2/GO-NH2 (GA= Graphene aerosol and GO= Graphene oxide) have shown great potentialin the adsorption of organonitrogen compounds like quinoline. However, research in the electrochemical application of these MOFs and their derivatives is limited despite their high surface area, abundant porosity, and increased conductivity. To demonstrate their electrochemical sensing potential, modification of the glassy carbon electrode (GCE) was suggested, which would show a higher degree of association for pyridine and quinoline on modified UiO-66-NH2/GA and UiO-66-NH2/GO-NH2 surfaces, thereby creating a more favourable route for adsorption. This would result in enhanced sensing of pyridine and quinoline in model fuel. Thus, unlike the bare GCE, the fabricated/modified can selectively detect high levels of organonitrogen compounds. In this study, Chapter 3, UiO-66-NH2/GA and UiO-66-NH2/GO-NH2 are prepared via the solvothermal method and then characterized using various spectroscopic and imaging techniques such as Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Ultraviolet-Visible Spectroscopy (UV-VIS), Thermogravimetric Analysis (TGA), X-ray Development of the Zirconium-based metal- organic framework UiO-66 for Adsorption-mediated electrochemical sensing of organonitrogen compounds in fuels.Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 202
Development of a numerical geohydrological model for a fractured rock aquifer in the Karoo, near Sutherland, South Africa
Get PDFThe regional scale method in groundwater storage observation introduces uncertainties that hinder the evaluation of the remaining lifespan of depleted aquifers. The scarcity of precipitation data presents significant global challenge, especially in semi-arid regions. This study constructs a regional numerical hydrogeological model that identifies the potential impacts of climate change on the water balance for the South African Gravimetric Observation Station in Sutherland. The purpose of this study is to understand mechanisms controlling groundwater in the fractured rock aquifer. The climate data from the Weather forecast data over the last ten years was collected from the South African Weather Service. and groundwater levels data assessed the potential impacts of climate change on water balance components, especially precipitation and evapotranspiration. Precipitation is the primary recharge parameter in this study and had the highest level recorded in winter, with May having the highest precipitation rates of 24,62mm. The instrument conducted two profile investigations in a single day to detect geological abnormalities at various depths, achieving an impressive accuracy of up to 0.001 mV. The fact that groundwater flows from regions of higher hydraulic heads to areas of lower hydraulic charges, confirms that riverbeds in Sutherland act as preferential conduits for subsurface recharge. The profile and processed geophysical maps show low chances of getting groundwater in this observed area due to extensively great depth, approximately 150 – 210 m. The river package from MODFLOW model shows little inflow to the study nearby well locations. These model results showed a negative difference between water flowing in and out of the system of about -7m3 between 2002 and 2020. Groundwater flows faster at borehole five, where the hydraulic conductivity is large. The resulting regional hydrogeological model offered valuable insights into how climate change might influence the distribution and accessibility of groundwater resources. In the context of Sutherland, a negative groundwater budget value signaled that groundwater extraction or consumption surpassed the natural replenishment or recharge of the aquifer.Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 202
Exploring the perceptions of coloured Christian lesbian Women of the influence of Christianity on their identity development
Get PDFSouth Africa is a nation of which the greater number of its citizens are followers of the Christian faith. Coloured people form part of this population, as the majority of Coloured people in South Africa consider themselves to be Christians. In the Christian faith, homosexuality is considered to be a sin and is frowned upon which may result in difficulty navigating identity development of members of the LGBTQIA+ community. This conflict may, in turn, greatly affect the identity development and overall wellness of these individuals who may want to hold onto a religious identify, but are in conflict, as their sexuality falls outside of what is considered acceptable. This research study sought to explore the perceptions of South African Coloured lesbian women, who follow Christianity, regarding the influence of religion on their identity development. This exploration was considered necessary as it contributes to a gap in the literature on the influence that religion has on identity development for a queer person. The research study was qualitative in nature and research participants were recruited by way of the purposive sampling strategy and 12 participants were interviewed. Semi-structured virtual interviews were conducted as the data collection tool to the research study. Ethical clearance to conduct this study, informed consent, voluntary participation, the right to withdraw participation from the research study, anonymity and confidentiality, and no harm of the participants are the ethical points that this study adhered to. The research study used thematic analysis to identify patterns in the data and Braun and Clarke’s data analysis technique was employed. The trustworthiness of this study, was guided by Lincoln and Guba’s four constructs; credibility, dependability, transferability and confirmability. The themes identified in this study were as follows: 1) The imposition on identity (subthemes of guilt and confusion; feelings of being lost and isolated); 2) The significance of race in prejudice against lesbian women; 3) Spiritual transition. The main finding of the aforementioned themes included an underlying understanding amongst they have at some point experienced uneasiness to “coming out” for fear of judgement as Christian lesbians. Although some participants were able to navigate through their identity development, they have experienced confusion and conflict in accepting all the different facets of their identity, simultaneously, due to judgement of other Christians who have imposed a “choose one or the other” mindset upon them. In addition, added minority stress within race factors were identified as a pinning point amongst participants, who felt that their experiences within their sexuality and religious interactions would be different, if they were other races. This highlights the triple minority stress that is faced by marginalised communities in South Africa. Finally, the participants expressed a transition away from religious communities, to a more spiritual relationship with their God, signifying a shift in religious interaction.Thesis (MA) -- Faculty of Health Science, School of Behavioural & Lifestyle Sciences, 202
Self-attentive vision in evolutionary robotics
No full textThe autonomy of a robot refers to its ability to achieve a task in an environment with minimal human supervision. This may require autonomous solutions to be able to perceive their environment to inform their decisions. An inexpensive and highly informative way that robots can perceive the environment is through vision. The autonomy of a robot is reliant on the quality of the robotic controller. These controllers are the software interface between the robot and environment that determine the actions of the robot based on the perceived environment. Controllers are typically created using manual programming techniques, which become progressively more challenging with increasing complexity of both the robot and task. An alternative to manual programming is the use of machine learning techniques such as those used by Evolutionary Robotics (ER). ER is an area of research that investigates the automatic creation of controllers. Instead of manually programming a controller, an Evolutionary Algorithms can be used to evolve the controller through repeated interactions with the task environment. Employing the ER approach on camera-based controllers, however, has presented problems for conventional ER methods. Firstly, existing architectures that are capable of automatically processing images, have a large number of trained parameters. These architectures over-encumber the evolutionary process due to the large search space of possible configurations. Secondly, the evolution of complex controllers needs to be done in simulation, which requires either: (a) the construction of a photo-realistic virtual environment with accurate lighting, texturing and models or (b) potential reduction of the controller capability by simplifying the problem via image preprocessing. Any controller trained in simulation also raises the inherent concern of not being able to transfer to the real world. This study proposes a new technique for the evolution of camera-based controllers in ER, that aims to address the highlighted problems. The use of self-attention is proposed to facilitate the evolution of compact controllers that are able to evolve specialized sets of task-relevant features in unprocessed images by focussing on important image regions. Furthermore, a new neural network-based simulation approach, Generative Neuro-Augmented Vision (GNAV), is proposed to simplify simulation construction. GNAV makes use of random data collected in a simple virtual environment and the real world. A neural network is trained to overcome the visual discrepancies between these two environments. GNAV enables a controller to be trained in a simple simulated environment that appears similar to the real environment, while requiring minimal human supervision. The capabilities of the new technique were demonstrated using a series of real-world navigation tasks based on camera vision. Controllers utilizing the proposed self-attention mechanism were trained using GNAV and transferred to a real camera-equipped robot. The controllers were shown to be able to perform the same tasks in the real world.Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 202
An Investigation into the challenges of translating mathematical terminologies into Xitsonga
Get PDFMathematics in South Africa is one of the subjects that is considered ‘difficult’ by many learners. The proof of this statement is reflected by the low mathematical pass rate in many South African schools. One of the challenges that has been highlighted by learners and teachers is that the language of mathematics is challenging. This implies that learners find it difficult to understand some of the mathematical terminologies and content that is being taught. The main reason for the challenge of grasping mathematical terminologies that has been cited by learners and educators is the language of learning and teaching (LOLT). Mathematics is taught in English in most South African schools even though many learners speak one of the indigenous South African official languages (if one excludes English and Afrikaans) at home and get to use and be exposed to English as the medium of learning and teaching only at school. While mathematics remains a challenge in South Africa, research shows that when home languages are used in a mathematics classroom, it enhances the learners understanding. However, it is not always simple to transfer mathematics from English to an African language. There are complexities associated with translation that include the lack of vocabulary in the target language which in this case is Xitsonga. The lack of terminologies in Xitsonga is one of the challenges that occur during the process of translation. This purpose of this research is to examine the challenges of translating mathematical terminologies from English into Xitsonga and to find the strategies that can be used to assist learners to improve their understanding of mathematics. As such, a qualitative research method will be used to select the mathematical terminologies extracted froma mathematics bilingual dictionary with the aim of examining the quality of the translation and identifying the challenges that have been experience by translators.Thesis (MA) -- Faculty of Humanities, School of Language, Media and Communication, 202
Factors affecting learning of English as a second language in South African schools
Get PDFThe aim of this study was to identify the factors that are affecting the learning of English as a second language in South African schools. Although many South African learners are not fluent or native speakers of the English language, they are required to learn the content of their subjects in English. This is because there is a lack of resources in South Africa to teach other languages and English is seen as the language that grants access to better education and job opportunities, and it is the language that is used to communicate worldwide. The input, output, interaction and sociocultural theories were used to inform the theoretical framework of the study. This study used both qualitative and quantitative methods in order to answer the research question. The participants for this study consisted of individuals who matriculated in South Africa within the period of the past five years and were taught English as a second language. The participants were approached through social media platforms. One hundred participants responded to the questionnaire and 14 were interviewed. The methods of conducting interviews and distributing questionnaires were used to help the researcher to gain a better understanding of the topic. The findings of this study indicate that there are still teachers in South African schools who are not well qualified or proficient in the English language. In addition, learners face a variety of challenges in learning English as a second language. These challenges are found not only within the school context but also outside of school. The learners’ external environment also influences their learning of English as a second language. These external influences include overcrowding at schools, lack of resources such as libraries or books, and parents who are not involved in their children’s learning of English. Being proficient in L1 is important in order develop L2 because a learner can use their L1 skills to learn L2. There are also affective factors such as motivation, confidence and anxiety that play a role in in learning a second language. One of the reasons that some learners perform better than others when it comes to learning English is because of the motivation and self-confidence that they possess. Anxiety related to learning English as a second language is seen as a threat to an individual’s self-concept. This is because learners might find it difficult to communicate well in a language they have not learnt completely. Learners need to be encouraged to achieve their best level in their English skills so that their learning outcomes can be improved. Also, in order for the literacy rate of poor performing schools in South Africa to be improved, teachers should be trained to teach the English language better, parents need to be involved actively in their children’s learning of English as a second language and the Department of Basic Education needs to develop programmes and a policy that puts emphasis on the use of English as a LoLT.Thesis (MA) -- Faculty of Humanities, School of Language, Media and Communication, 202
Discipline and dismissal of employees For testing positive for cannabis
Get PDFEmployers are legally obligated to provide a safe working environment for all employees. They are permitted to enforce rules that regulate the use of cannabis, including a total prohibition thereof in the workplace. Most employers adopt a policy with a zero-tolerance approach to substance abuse in the workplace, especially considering the negative effects of substances. Cannabis is regarded as a drug and the effects of cannabis may negatively affect the health of employees. In most instances, users develop cognitive impairment which may result in decreased working memory function. Therefore, employers must test employees when they suspect that an employee have contravened a workplace policy. There are various tests that can be used to detect THC, the preferred method for testing employees is a urine test. Upon testing an employee, the test may show a positive result for the previous use of cannabis, but it does not determine the level of impairment. However, employers are still required to take the necessary disciplinary action against employees. In the following chapter, I shall discuss the judicial approach towards employees who have tested positive for cannabis.Thesis (LLM) -- Faculty of Law,(2024
Defining and regulating de facto and shadow directors: lessons from New Zealand
Get PDFThe term ‘director’ is commonly limited to those persons who have been validly appointed as directors. These directors are referred to as de jure directors. However, this is not the only type of director found in practical corporate settings. There are also those who have not been validly appointed as a director, who nonetheless act as directors and who are held out by companies as such. These persons are known as de facto directors. An individual who has not been validly appointed as a director, who is not held out by a company as such, but who still exercises some measure of control over the affairs of a company, is known as a shadow director. The existence of de facto and shadow directors is not peculiar to South Africa. New Zealand has seen fit to regulate de facto and shadow directors and has done so for over 70 years. Owing to the ambiguous wording of the definition of ‘director’ contained in the Companies Act, there is uncertainty whether the current definition in the Companies Act 71 of 2008 extends to de facto and shadow directors. This uncertainty resulted in the non-regulation of these forms of directorship. The Act only applies to those individuals who fall within the definition of ‘director’. The practical effect of this is the absence of clear avenues of accountability to those who occupy a position of power within a company without being appointed as a de jure director. Considering this, the core objectives of this research are to illustrate the far-reaching consequences of the non-regulation of de facto and shadow directors and how this problem may be remedied.Thesis (LLM) -- Faculty of La
Exploiting continuous flow technology to develop synthetic processes for active pharmaceutical ingredients: prilocaine and betrixaban
Get PDFThe dilemma of providing affordable health care has long haunted African countries due to the continuously growing disease burden as the population increases. Africa accounts for only 3 % of global drug production and imports over 90 % of its life saving medicines at a yearly cost of US$14 billion according to the African Development Bank (AfDB). Attaining Africa’s Agenda 2063, Universal Health Coverage (UHC) and Sustainable development Goal 3 (SDG3) aspirations of ensuring healthy and well-nourished citizens remain difficult given this situation. This over-dependence on imports has led to drug shortages, high pricing, poor quality medicines and unguaranteed supply chains, thus there still remains an unmet need. The advent of the COVID-19 pandemic worsened this situation as many countries curbed exports resulting in a crisis across the continent. Africa experienced high demand of medicines compared to prepandemic level, which threatened the health care of the continent. This situation can be addressed by establishment of local pharmaceutical manufacturing capability through adoption of advanced manufacturing technologies such as continuous flow chemistry. In this research, we therefore seek to exploit continuous flow chemistry, an enabling technology to develop safe and efficient synthetic processes for active pharmaceutical ingredients: prilocaine and betrixaban as case studies. To the best of our knowledge there is no reported work on synthetic processes towards prilocaine and betrixaban under continuous flow conditions, thus this research extensively unearthed interesting continuous flow processes towards these APIs. In a broader view, establishment of local APIs production will ease Africa’s over-dependence on imports, which will in turn address issues such as drug shortages, poor quality and high pricing. This work aims to demonstrate how continuous flow technology can be useful for the establishment of local APIs manufacturing, which will inherently revolutionize medicines availability, affordability and accessibility to the greater population. Chapter one begins with a brief overview on Africa’s disease burden and pharmaceutical supply chain. Continuous flow chemistry is introduced with its benefits and limitations discussed. Lastly a mini review of examples of APIs synthesised in continuous flow is presented. In chapter two, we demonstrate how continuous flow technology can be exploited to develop synthetic processes towards prilocaine as our first case study. This chapter clearly demonstrates how highly exothermic nitration reactions can be safely handled by using continuous flow systems. Additionally, the use of a micro structured mixer facilitated biphasic nitration of toluene to be carried out with enhanced mass transfer, which inherently led to improved selectivity of ortho-nitrotoluene (preferred isomer) to 79 % compared to 59 % achieved in batch mode. A two-step synthesis of ortho-toluidine via biphasic nitration of toluene and nitroreduction was demonstrated with the incorporation of a Zaiput liquid/liquid separator to facilitate in-line separation. Comprehensive optimisation studies were carried out in flow. Prilocaine was synthesised in 74 % overall yield in a 13.6 min residence time for all processes. In chapter three, we demonstrate how continuous flow technology can be exploited to develop synthetic processes towards betrixaban. Synthetic routes towards betrixaban feature two amide bond formation transformations. Pleasingly, we explored multistep chemistry to develop amide synthesis protocols in flow without interruption for work up and isolation. An overall yield of 92 % was achieved to get to key intermediate to betrixaban in 8 min total residence time. Chapter four demonstrates the robustness of developed amide synthesis protocols, a key transformation in synthetic routes towards prilocaine and betrixaban in continuous flow systems. A total of 22 amides were synthesised via flow multistep processes with isolated yields greater than 82 %. All the compounds were characterized using infrared spectroscopy (IR), and nuclear magnetic resonance (NMR). Quantification of the reaction mixtures were carried out using highperformance liquid chromatography (HPLC) and gas chromatography (GC).Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 202
Collaborative conservation governance in multifunctional landscapes: a contextual analysis of two South African biosphere reserves in the Boland
Get PDFThe Man and the Biosphere Programme (MAB) has been earmarked as one of the most promising ways of tackling the grand challenges of our time and achieving the Sustainable Development Goals. Furthermore, it may have the potential to make positive contributions to one of the most troubling conservation challenges of our time – winning spaces for large carnivores in human-dominated landscapes. This study aims to assess the interpretation and implementation of MAB in two South African Biosphere Reserves (BRs) and explore how BRs as landscape level collaborative initiatives can support Cape leopard conservation in the Boland region of the Western Cape, South Africa. This study is informed by two objectives. First, to understand how the chosen governance strategy and structure of two South African BRs have helped to achieve a context appropriate interpretation and actioning of MAB in the landscape. Second, to understand how landscape-level collaborative conservation initiatives support leopard conservation across a multifunctional landscape. This study takes on a mixed methods approach in which qualitative data takes priority and quantitative data is used for support in an embedded multiple-case study design. The sampling techniques used include purposive sampling of strategically targeted participants, i.e. those governing BRs and those leading the collaborative initiative and snowballing thereon. Data collection included a combination of semi-structure interviews (n=20) (the principal collection method), a review of archival, policy and other documents (n=15), and supported by a mixed methods survey questionnaire (n=5). Data were analysed through thematic and content analysis. Findings suggest that organisations working at a landscape-level utilise forms of adaptive co-management and/or governance as a means to being both adaptive and collaborative. Important themes which emerge include cross-sectoral approaches, networks, leadership and trust for building partnerships, shared visions and ‘filling gaps’ left by, or collaborating with the state to fulfil mutually beneficial objectives. This research provides empirical studies on MAB, important for sharing knowledge across the World Network of BRs, meeting the need for further research on collaborative initiatives in social-ecological systems and conservation programmes for large free-roaming carnivores in multifunctional landscapes.Thesis (MSc) -- Faculty of Science, School of Natural Resource Science & Management, 202