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Chemostratigraphy of the lowermost iron-manganese cycle of the Hotazel Formation, and implications for its primary depositional environment

  • Authors: Masoabi, Ntseka Thomas
  • Date: 2022-10-14
  • Subjects: Chemostratigraphy , Great Oxygenation Event , Manganese ores Geology South Africa Northern Cape , Banded iron formation
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/362938 , vital:65376
  • Description: The giant Kalahari Manganese Field (KMF), located in the Northern Cape Province, South Africa, comprises approximately half of the world’s manganese resources, estimated at about eight billion tons at grades ranging from 20-48 wt%. The KMF is linked to a period in geological time when the Earth’s atmospheric and oceanic conditions underwent a major transition from oxygen-deficient to oxygen-enriched conditions – an event famously referred to as the Great Oxidation Event (GOE) that occurred around 2.4 Ga. The KMF deposits are hosted in Banded Iron Formation (BIF) of the Paleoproterozoic Hotazel Formation in the uppermost Transvaal Supergroup. The sedimentary Mn ores are interbedded with Hotazel BIF in the form of three alternating depositional cycles of BIF, transitional hematite lutite and laminated, carbonate-rich manganese ore. The lowermost and thickest of the three cycles is the most economically significant and has been mined for several decades on a large scale from the southernmost KMF. In this study, two drill cores from the southern KMF were inspected, logged and sampled at a high resolution of approximately half-meter interval per sample. The selected cores, namely G774, capturing the lower portion of the Hotazel Formation from the Mamatwan locality, and MP-56, capturing the corresponding portion from the Middleplaats locality, are geographically proximal to each other, with a horizontal distance of roughly 3 km separating the two of them. The G774 drill core is characterized by a conspicuously thick manganese layer covering a thickness of 50 m, with the overlying BIF reaching a total thickness of 11 m. The MP-56 drill core, on the other hand, has a relatively thinner corresponding manganese layer of 30 m in thickness, while the overlying BIF layer exhibits a thickness of 24 m. The extent of sampling up-section was constrained by an apparently coeval black shale layer which represents the chosen upper stratigraphic marker for the lower part of the Hotazel section in the broader area that is under investigation in this thesis. That way, a high resolution chemostratigraphic approach was employed to elucidate the potential factors contributing to the relative sedimentary lateral thickness variations seen across the southernmost KMF. High-resolution geochemical data were used to explore relationships and signals that might constrain relative precipitation rates for iron and manganese against detrital species, fluctuating redox conditions in the original environment of deposition, and chemostratigraphic correlation. All geochemical data (i.e., major oxides, minor and trace elements and carbonate carbon isotopes) were obtained respectively through employing X-ray Fluorescence (XRF), Laser Ablation Inductively Coupled Mass Spectrometry (ICP-MS), and Gas-source mass spectrometry. Comparative considerations made between the bulk geochemistry of the two sequences (i.e., Mamatwan and Middleplaats sections) reveal that periods of high-Mn deposition in the Hotazel Formation appear to be very Ca-carbonate rich (as indicated by high CaO, LOI and Sr concentrations). This, in turn, suggests that the Mn abundance is in the Hotazel ores is controlled mainly by the silicate phase braunite and is diluted by the deposition of Ca-carbonate through time. Bulk-rock concentration results for trace elements of the High Field Strength Element (HFSE) group (namely Zr, Hf, Y, Nb and Sc) were utilized to constrain the rates of either clastic and/or volcanic detrital inputs, as they traditionally represent refractory mineral particles of a common detrital/volcanic origin. The two chemosedimentary sequences preserve these elements in very low and thus quantitatively negligible concentrations – suggesting that the Hotazel depositional environment received very low and insignificant influx of a terrigeneous detrital component. A selection of these elements was therefore used to deduce, with caution, the relative as opposed to absolute precipitation rate of the major chemical constituents (i.e., Fe + Si vs Mn + carbonate), assuming a constant detrital flux through time. It was found that the relative abundances of Zr, Y and Nb is roughly 1.5 – 2 times as high in the BIF lithofacies relative to the Mn ones at both localities. This led to the inference that the Mn-enriched portion of the sediment must have been deposited at approximately twice the rate that the Fe-rich (BIF) portion was originally deposited. In terms of redox-sensitive elements, the elements Co and Mo seem to reveal the most valuable insights into the redox environment of primary chemical deposition. Cobalt displays a unique pattern in that its highest concentration is attained at the hematite lutite transitions (similarly with the REE in this regard), while very low and seemingly invariant concentration is exhibited within the core of the main orebodies. The same pattern seems to be reproduced to a degree by the corresponding bulk MgO component, whereby MgO abundance maxima are associated with the basal hematite lutite and the hematitic flanks of the Mn-ore zone, while the core of the Mn-rich layer attains relatively low and essentially invariant MgO concentrations. This implicates a close and direct association of Co with the hematite fraction of the rocks and a concurrent enrichment in Mn-rich carbonate (dolomite). On the other hand, Mo seems to have a direct and clear association with peak MnO2 content of the rocks, which in turn presents a high possibility of Mo having adsorbed onto primary Mn-oxyhydroxides in the water column, thus providing evidence that Mn-oxide must have acted as an important Mo sink, at least locally. Finally, the carbonate-carbon isotope results provide a useful tool that brings the two stratigraphic sections “together“, in conjunction with other correlatable chemostratigraphic parameters (e.g. Co, Mg). The results demonstrate that bulk carbon fluxes and isotopic signals in the sediments must reflect primary processes of deposition, and that correlation across two apparently disparate lithostratigraphic sections can be effected. The key finding is that, at times, manganese deposition in one part of a vii stratified basin was evidently accompanied by simultaneous BIF deposition at another, thus painting a very complex picture of massive primary chemical precipitation of Fe and Mn at the dawn of the GOE. , Thesis (MSc) -- Faculty of Science, Geology, 2022
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  • Date Issued: 2022-10-14

Colonial displacements and African coping strategies: The experience of BaTonga of Binga, Zimbabwe, 1956-2008

  • Authors: Dhodho, Codelia Govha
  • Date: 2022-10-14
  • Subjects: Tonga (Zambezi people) Refugees , Subsistence farming Zambezi River Valley , Hunger Zambezi River Valley , Food security Zambezi River Valley , Adaptability (Psychology) , Food relief Zambezi River Valley , Non-governmental organizations , Kariba Dam (Zambia and Zimbabwe)
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/327642 , vital:61139 , DOI 10.21504/10962/327642
  • Description: This study examines the challenges faced by BaTonga in livelihood reconstruction after involuntary displacement and resettlement from the Zambezi valley to pave way for the Kariba dam reservoir. It shows how they were forcibly evicted without compensation because of the racist policies of Southern Rhodesia. Their resettlement into an arid region infested with marauding elephants, malaria and tsetse fly undermined their complex livelihoods and eroded their self-sufficiency, but the study argues that they were active and resilient agents who adopted complex coping strategies. It shows how they had to adapt to dry-land farming and counter the effects of wildlife which plundered their crops and managed to secure the harvest in the drought-prone region. The study shows that although they adopted precarious livelihoods, they managed to survive under extreme circumstances for decades without any external assistance until the coming of NGOs who began to distribute free food from 1982. It argues that prolonged distribution of emergence food aid may not have been necessary, but its coming for almost three decades largely served political interests of both the NGOs and their governments. This perpetuated poverty as BaTonga also manipulated its distribution as a coping strategy against fragile livelihoods. This caused dependency which further plunged them into chronic food insecurity because they abandoned their traditional coping strategies. The study argues that both the colonial and postcolonial government as well as NGOs failed to address the root causes of livelihood insecurity in Binga for the five decades under study. It is therefore the contention of this study that the problem of food insecurity in Binga was not only an issue of recurring drought but was deeply rooted and pervasive due to multiple complex factors which made it difficult for the people to establish sustainable food production after displacement. , Thesis (PhD) -- Faculty of Humanities, History, 2022
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  • Date Issued: 2022-10-14

Composition Portfolio

  • Authors: Hanmer, Paul Dylan
  • Date: 2022-10-14
  • Subjects: Composition (Music) , String quartets Scores , Symphonies Scores , Music South Africa
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/327283 , vital:61100 , DOI 10.21504/10962/327283
  • Description: Extract from Introduction: “In the cover bands I worked with, I used to do what all my colleagues in these bands were doing to learn and remember repertoire; transcribe “by ear” and then rehearse with the whole band. Later, when I joined “909” [a cover band named after the “909” model of drum-box developed and built by the Japanese company, Roland] I learned to extend that skill by notating my transcriptions and then playing from these self-made keyboard parts. All the instrumentalists in that band likewise played from their own notated transcriptions and, from that time onward it became rarer for me to do any kind of performance work without a set of self-made parts to read from or refer to. I had thus reverted to performing from musical notation. Even later, when I became involved almost exclusively in improvisational music performance, I never quite abandoned the notion of having notated keyboard or piano parts to hand, as a reference or guide. Since about 1990, I have led a life that has increasingly left pop music behind and instead embraced working with improvising musicians; those who wish to explore South African folk idioms in their compositional and performance output, as well as others who have a deep love of jazz music. At the same time, I have re-entered the realm of classical music and music-making; often through writing arrangements of my own music, which would incorporate classically trained players, as well as in response to commissions to compose [for particular musicians or groups of musicians] fully notated pieces of music – such as the works in this PhD portfolio. Yet, there are many circumstantial factors that feed into my composing, and exert an influence on my creativity. A major step in this particular direction came during 2002 when composer, Michael Blake, asked me to contribute to The Bow Project. This commission brought me into close contact with the [then intact and very active] Sontonga Quartet. Several further requests for, and commissions of, new works followed on from there. Two such works constitute the major portion of the portfolio to which these reflexive commentaries refer.” , Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2022
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  • Date Issued: 2022-10-14

Conceptualising mental distress from an African psychology paradigm: using an interpretative phenomenological analysis of the views of traditional healers

  • Authors: Nabo-Bazana, Sandisiwe Sifanelwe
  • Date: 2022-10-14
  • Subjects: Healers South Africa , Traditional healer , Mental distress , Black psychology , Afrocentrism
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/406213 , vital:70249
  • Description: With South Africa's long history of colonialism and racial oppression, there are still services in the country that many South Africans cannot relate to, including psychology. Research shows that many South Africans experience and are affected by mental distress due to several factors, including poverty, unemployment, and traumatic experiences. Managing and treating such distress has always been challenging for most South Africans. Some debates question the relevance of psychological services from the West in a South African context. This study explores other approaches to psychology that look beyond the Biopsychosocial model when dealing with certain types of disorders in an African context. African psychology, or the Afrocentric approach, looks at what is beneath the surface, not just the presenting problem. Mainstream psychology strives to be universal and applicable to all. However, African psychology disagrees with this notion. African psychology perceives human beings as strongly influenced by social and cultural influences. The focus of this approach includes the spiritual realm and the attached meanings. There is evidence for the need to merge Traditional and Western medicine. The research methodology for this study is qualitative, using Interpretative Phenomenological Analysis. IPA allows for a critical engagement with the ways in which participants construct their reality. The researcher carried out semi-structured interviews to enable participants, all traditional healers (3 female and 2 male), to narrate their experiences dealing with mentally distressed clients. The accounts of these traditional healers were analysed focusing on people who have experienced mental distress. From the analysis and synthesis of the themes, findings illustrate how traditional healers conceptualise and construct mental distress from an African Psychology paradigm. An emerging core theme was the importance of the divine call and its influence on the chosen treatments. More studies are needed to illustrate the potential for collaboration between African Traditional healing and EuroAmerican healing practices, to provide holistic services to people in need. , Thesis (MA) -- Faculty of Humanities, Psychology, 2022
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  • Date Issued: 2022-10-14

Constraints on Cr-PGE Mineralisation Models: Geochemical and petrological studies in the Middle Group 1 and 3 Chromitites, Western Limb, Bushveld Complex, South Africa

  • Authors: Arunachellan, Yogendran
  • Date: 2022-10-14
  • Subjects: Chromite South Africa Bushveld Complex , Mineralogy South Africa Bushveld Complex , Geochemical surveys South Africa Bushveld Complex
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/362730 , vital:65357
  • Description: The Bushveld Complex in South Africa has been of interest in various research groups for decades, along with diverse theories regarding its origin, formation, and emplacement. These theories include magma mixing, contamination, and changes in the chamber's ephemeral parameters. Of interest for our current study is the formation of the middle group chromitite layers in the Western Limb. In this research, we aimed to determine the emplacement mechanism of the MG group chromitites by scrutinising the MG 1 and MG 3 layers. In core KD 151, the focus was placed on the MG 3 and MG 1 chromitite layers and their associated silicate rocks; on these regions of the core, time was spent for detailed observations. The differences and similarities of these layers were explored as the study advanced. The objectives were to determine the in-situ or proximal crystallisation of the chromitite by evaluating mineral textures and compositions. This required that we determine the characteristics of the immediate HW (hanging wall) and FW (footwall) to these chromitites, with insights into the relationship that anorthositic zones may offer and examine the PGE profiles of the chromitites in contrasting lithological settings. The sampled borehole was in the Western Limb of the Bushveld Complex; the immediate HW, chromitite layers and FW were divided into sections (2.5 x 5 cm) along selected horizons for a microscale study. The preliminary results of a study on the sub-economic Middle Group (MG) layers within the Critical Zone (CZ), contrasting the MG 1 (Lower CZ) and MG 3 (Upper CZ) chromitite layers of the Rustenburg Layered Suite of the Bushveld Complex, South Africa were analysed. The MG 3 and 1 suites of silicate rocks show disequilibrium textures between the pyroxenes and plagioclase, forming discontinuous olivine rims. These reaction rims are interpreted as products of magmatic aqueous fluid-facilitated reactions with minerals in a sub-solidus state. Deformation of the plagioclase was also noted in MG 1; this fracturing indicates either the transportation of these minerals or compaction by an overlying crystal mush. The MG 3 package of plagioclase, pyroxene and chromite compositions range from An67-78, En71-86 and Cr# of 68-84, respectively. The MG 1 package of plagioclase, pyroxene and chromite compositions are An64-91, En79-88 and Cr# of 70-80, respectively. The Cu/Pd ratio decreases from the base of the FW as it approaches the base of the chromitite, then remains low within the chromitite layer and finally increases upwards in the HW. These trends are observed in both the MG 3 and 1 package, therefore not influenced by the sulphide control. There is a decrease in both IPGE and PPGE upwards as the HW progresses into the chromitite. The FW levels of Ir and Ru increase upwards immediately adjacent to the FW contact, while Pd and Rh concentrations decrease. The whole-rock Mg# indicates a decrease in the MG 3 with a uniform increase in the HW and an erratic upward increase observed in the FW. The chondrite normalised PGE plots show a bell-shaped curve which is evident for the En content of the pyroxenes and the content of plagioclase with the highest values in the chromitite layer itself. The Cr# of the chromite decreases upwards with the highest values along the FW. The Cu/Pd ratio for MG 1 indicates chromitite control rather than sulphide control of the PGE. The whole-rock Mg# decreases in MG 1 with higher uniform values observed in the HW and FW. The geochemical and petrological data from the MG group study revealed that in situ fractional crystallisation seems unlikely as the sole mechanism for their formation in the CZ. A model is suggested in which the migration and transport of a magmatic slurry type suspension with accompanying hydrous fluids would likely have resulted in the emplacement of these chromitite packages along with the PGE mineralisation of the chromitites. , Thesis (MSc) -- Faculty of Science, Geology, 2022
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  • Date Issued: 2022-10-14

Contextualising job satisfaction amongst lowest paid support staff in a Higher Education institution

  • Authors: Madito, Gotlannamang Moloiesi Boipelo
  • Date: 2022-10-14
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/405984 , vital:70225
  • Description: Thesis embargoed. To be relased in 2024. , Thesis (MA) -- Faculty of Humanities, Psychology, 2022
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  • Date Issued: 2022-10-14

Country risk and stock market volatility in Africa: Measuring the contribution of political and economic risk factors

  • Authors: Hoveni, Jamela Basani
  • Date: 2022-10-14
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/405445 , vital:70172
  • Description: Thesis embargoed. To be released in 2025. , Thesis (PhD) -- Faculty of Commerce, Economics and economic History, 2022
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  • Date Issued: 2022-10-14

Cyborg bodies and the search for self: an ethnographic exploration of supportive technologies as tools to mitigate daily distresses

  • Authors: Kibane, Lebogang Zandile
  • Date: 2022-10-14
  • Subjects: Posthuman , Posthumanism , Anthropology , m-health , Wireless communication systems in medical care , Cyber-ethnography , Distress (Psychology)
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/408625 , vital:70510
  • Description: This dissertation explores the ways in which individuals embody cyborg realities through engaging with technological aids. It examines how these interactions have the potential to bring to light new ways of thinking about and experiencing daily distresses. Pertinent human technology interaction was observed through an overarching cyborg lens, embedded in posthumanist thought. The study began with a “human as cyborg” ontology that sought to impress upon readers the intimacy with which technology is entangled in our lives. It aimed to call to attention the use of the cyborg myth as it is concerned with “transgressed boundaries, potent fusions, and dangerous possibilities” (Haraway, 1985:7). The study followed a cyber ethnographic strategy, where cyber ethnography refers to a virtual research method that observes social and cultural phenomena that are mediated by online interactions. Data was collected over a period of eight months, beginning in December 2020 and ending in July 2021. It was collected through the following means: a short self-administered online questionnaire, computer mediated in-depth interviews, and group interviews. I also kept a journal on reflections of my own use of these supportive technologies. After analysing the results of in-depth interviews with nine primary participants and twenty-six online questionnaires, the following key themes were brought to light: Firstly, the tethered self, or cyborg self, engages in evolved acts of ‘care of the self’ mitigated through supportive technology use. Secondly, access to new technologies brings about new ways of performing the self. Thirdly, engagement with supportive technologies provides opportunity for aiding distress in the way of encouraging self-reflective and self-interrogation behaviours as seen in mobile health app use. This constant self-interrogation behaviour in turn develops a kind of technological dependency, characterized by escapism and evolved methods of self- soothing. Lastly, exploring the use of technology to aid distress revealed that technologies generate equal opportunities for improved well-being, as they do for a decreased sense of connectedness and security. The research demonstrates that supportive technology use is entangled in the fabric of our everyday lives. Through it we fashion our identities, alleviate distress, evade distress, and discover new causes of distress. , Thesis (MSocSci) -- Faculty of Humanities, Anthropology, 2022
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  • Date Issued: 2022-10-14

Demand-side factors and the employment of young people: A case study of the recruitment and selection strategies of selected firms in Johannesburg

  • Authors: Gabobegwe, Maoshadi Keletso Amanda
  • Date: 2022-10-14
  • Subjects: Unemployment South Africa , Underemployment South Africa , Unemployed youth South Africa , Labor market South Africa , Employees Recruiting South Africa , Employer attitude surveys South Africa , International Labour Organisation
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/327294 , vital:61101 , DOI 10.21504/10962/327294
  • Description: Unemployment is a long-standing and pressing socio-economic phenomenon that affects, markedly, both developed and developing countries. Although, in one way or another, many people are affected by unemployment, the reviewed literature concurs that youth unemployment is a critical component of the overall unemployment challenge. Indeed, the burden of unemployment is borne, tremendously, by young people, especially those who are Not in Education, Employment, or Training (NEETs). The International Labour Organisation (ILO) has declared youth unemployment a global crisis, with approximately 67,6 million unemployed young people worldwide in 2018. In South Africa, the youth unemployment rate escalated to 56.4 per cent in the second quarter of 2019. This disturbing level of unemployment among young people poses a serious threat—for as long as young people stay unemployed. Indeed, the cost of unemployment is too high, not only does it engender discontent among young people who are floundering in poverty and frustration, but it can also trigger or perpetuate all sorts of social, political, and economic effects. These effects only exacerbate the already intricate and onerous global agenda of tackling unemployment— because they give rise to other socio-economic ills (e.g., crime, among others) that also need to be addressed. Owing to this grave and perpetual challenge of unemployment, exploring and understanding the dynamics of youth unemployment continues to be of paramount importance worldwide. This thesis, in particular, seeks to investigate the factors that impede on the employment of the NEETs category, as it may be extremely difficult for them to enter the labour market— and they may lose hope of entering the labour market later in life, if they are unsuccessful while still young. Unlike graduates or other youth categories (i.e., matriculants) who have better chances in the labour market, some young people (by virtue of being ‘dropouts’, teenage moms/dads, having failed matric, among other reasons), remain the most vulnerable to unemployment. For this reason, the primary aim of this thesis is to examine the ways in which employers’ recruitment strategies advantage or disadvantage young people (NEETs). The secondary aims include: (a) examining how employers' perceptions and attitudes, regarding the NEETs youths, influence their recruitment decisions when it comes to employing young people; and (b) understanding the ways in which government strategies (devised to combat youth unemployment) influence employers’ decisions to recruit the youths’ or not. In essence, this study seeks to explore the demand-side factors in the labour market that can help us understand how employers’ recruitment decisions (or recruitment behaviour) affect the employment prospects of young people in the labour market. The focus on demand-side factors is motivated by Labour Market Segmentation (LMS) theories, which serve as the theoretical framework of this thesis. LMS theories’ significance lies in their opposition to neoclassical economics, that posit the existence of a unified labour market (which operates like all other markets), consisting of buyers and sellers in ‘free’ competition. According to neoclassical theory, the difference between workers’ employment and wages is determined by ‘individual preferences’ and investments in ‘human capital’ (skills, experience, formal education, etc.). By contrast, LMS theorists argue that labour markets are fragmented, and that differences on the demand side imply differences in compensations that are not totally determined by individual workers' human capital. Inspired by the claims of LMS theories, this study elected to explore demand-side factors by applying qualitative research methods and techniques to gather and analyse the data gathered, and to ultimately address the research objectives. In particular, non-probability sampling was used to sample 20 firms from four sectors (manufacturing, retail/hospitality, finance, transportation) in the Johannesburg (CBD) region. The respondents were all asked a series of semi-structured questions in order to yield qualitative results that would help determine the employers’ dispositions towards young people; and about the government’s strategies that address youth unemployment. The aim is to provide an in-depth, nuanced understanding of how the respondents’ dispositions influence the inclusion or exclusion of young people in the employers’ recruitment considerations. The aggregate results of the study generally indicate that—although there are innumerable factors that affect young peoples' employment prospects—young people (without skills and tertiary education or matric) are actually being employed, and are still being considered for employment by the majority of the sampled employers (predominantly from retail/hospitality firms). Only a minority of employers stated, categorically, that they do not employ young people, and do not intend to do so. Conversely, the results also reveal that the the majority of employers often recruit young people for general and entry-level jobs that are often offered on a non-standard employment basis. At face value, the employment of young people (without skills) in the majority of the sampled firms may seem to make a difference—and it probably does, for as long as young people are exposed to the world of work. However, in the 4 grand scheme of things, the kind of employment offered in these firms is also problematic, because it is, basically, transient and unsustainable. As such, the young people that occupy these jobs are most likely to find themselves back in the unemployment queues whenever the ‘part-time’ or ‘temporary’ employment contracts are terminated. These jobs are especially problematic because policies such as the National Development Plan (NDP) 2030—in line with Sustainable Development Goals—aim to reduce poverty by creating sustainable employment. Contrarily, these kinds of jobs make it hard to achieve poverty reduction, because they are inherently unsustainable and barely lift people (especially young people) from unemployment and poverty. Based on these results, it can be asserted that the proliferation of non-standard employment compromises the agenda for decent work, and it delays the already sluggish Sustainable Development goal of creating sustainable employment (among other goals). This, then, reveals that there is still a stark and long-standing need for more radical strategies that will ensure the creation of sustainable jobs—without which the unemployment crisis will be far from over. Moreover, the results further indicate that the reasons why the minority of the sampled employers do not employ young people boil down to the fact that young people usually do not have what employers look for in their potential recruits; or that young people do not have what employers believe will contribute to the growth and productivity of their firms. In essence, employers will never employ any young person (or any jobseeker in general) that will be a liability than an asset in their firms. Over and above, this thesis corroborates many of the explanations—encapsulated in the growing literature—for rising unemployment, as well as the claims that unemployment is highly pronounced among young people. However, the contribution of this thesis is that it further offers a nuanced view to understanding the demand-side factors (as additional determinants) that hinder the employment of young people (especially those who make up the NEETs category). , Thesis (PhD) -- Faculty of Humanities, Sociology, 2022
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  • Date Issued: 2022-10-14

Design, synthesis, manufacture, characterization and evaluation of lipid nanocapsules in chitosan-iota-carrageenan based hydrogel scaffold as a potential anti-Covid-19 drug delivery system

  • Authors: Mukubwa, Grady Kathondo
  • Date: 2022-10-14
  • Subjects: Nanocapsules Design , Hydrogel , COVID-19 (Disease) , Characterization , Drug delivery systems
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/364955 , vital:65665
  • Description: Covid-19 is a deadly viral disease that has been rampant around the world since 2019. Although the successful introduction of the vaccine has reduced the spread of covid-19, new cases and deaths are still being recorded. To date, no specific curative antiviral treatment has been approved for covid-19. However, many existing antiviral drugs have been and are still being studied against covid-19 and some of them, such as Remdesivir, have shown promise and could be repurposed to treat this infection. Unfortunately, antiviral drugs are prone to resistance as most of them have poor biopharmaceutical properties, including low solubility, permeability and bioavailability, which could hinder any clinical success. Recent advances in nanotechnology-based delivery systems have made it possible to improve the biopharmaceutical properties of many drugs, especially those of poorly water-soluble drugs, by formulating them as lipid nanoparticles (LNP). Thus, in order to contribute to the fight against covid-19, this work aimed to develop Lipid Nanocapsules (LNC), based on some natural raw materials, which could improve the biopharmaceutical properties of antiviral drugs. In addition, since covid-19 infection is mainly respiratory, this work also aimed to fabricate a targeted delivery system based on a hydrogel capable of entrapping LNC and ensuring their efficient deposition and release in the lungs. The LNC consisted of a mixture of medium-chain triglycerides oil (MCT oil), crude soy lecithin, tween 80, NaCl and water, while the hydrogel consisted of a chitosan-grafted-iota carrageenan-grafted-poly (acrylamide-co-acrylic acid) system (CS-iCar-p (AAm-Co-AA)). Efavirenz (EFV), a drug with very low water solubility that has recently been demonstrated to have the potential to influence sars-cov-2 life cycle through different targets (3CLP, RdRp, Hellicase, 3’to5’exonuclease, 2’-O-ribose methyltransferase and EndoRNAse), was chosen as the model drug to evaluate the developed delivery system. The combination of LNP and hydrogel results in a delivery system known as the LNP-hydrogel composite, an emerging area of research in the field of drug delivery. To date, no research has reported the design and fabrication of an LNC-CS-iCar-p (AAm-Co-AA) hydrogel composite that could effectively deliver an antiviral drug to the lungs in addition to its advantages in terms of biological activities. Prior to the design of experiment, EFV solubility was assessed in water, labrafac lipophile 1349 and MCT oil. After that, the Design Expert Software version 13 was used to design the different experiments performed in this work. The I-optimal mixture design of experiments was performed for both LNC preparation and CS-iCar-p (AAm-Co-AA) hydrogel synthesis to study the impact of raw materials on the characteristics of these delivery systems. LNC were prepared using the phase inversion method while the free radical precipitation graft copolymerization method was used to synthesize hydrogel. In order to build polynomial models that could predict the amount of drug both LNC and CS-iCar-p (AAm-Co-AA) hydrogel can entrap, a D-optimal (custom) randomized design was performed. Moreover, various characterization techniques were used to investigate the physicochemical properties of the developed delivery systems. Thereafter, drug release studies were performed using a 1% sodium lauryl sulfate solution adjusted to either pH 4 or 7. Solubility studies revealed that EFV was more soluble in labrafac lipophile 1349 and in MCT oil than in water; therefore, given its affordability, MCT oil was used for the LNC formulation. The design of experiment carried out allowed the construction of polynomial models that could predict, on the one hand, the droplet size, the polydispersity index and the Zeta potential of LNC, which were respectively around 50nm, below 0.2 and below -33. On the other hand, the model could predict the swelling capacity of the synthesized hydrogel, which was optimised to about 30,000% (300 g of water to 1 g of hydrogel). This turned out to be influenced by the proportion of polymers, the ratio of monomers as well as the concentration of the cross-linking agent. In addition, the characterization techniques further supported the improvement of EFV solubility by highlighting its conversion into its amorphous state after encapsulation in LNC. They also confirmed successful synthesis of CS-iCar-p (AAm-co-AA) hydrogel. LNC were able to encapsulate about 87% of EFV while the synthesized CS-iCar-p (AAm-co-AA) hydrogel entrapped around 53% of EFV encapsulated in LNC. While LNC were able to release 42% and 27% of EFV after 74 hours in a 1% sodium lauryl sulfate solution (SLS) at pH 7 and pH 4 respectively, the LNC-CS-iCar-p (AAm-co-AA) hydrogel composite released about 50% and 40% of the drug after 9 days in the same release medium. Interestingly, the chemical integrity of the drug was preserved throughout the manufacturing process up to after its release, suggesting that the developed LNC-CS-iCar-p (AAm-co-AA) hydrogel composite could be used as a novel potential anticovid-19 drugs delivery system. , Thesis (MSc) -- Faculty of Science, Chemistry, 2022
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  • Date Issued: 2022-10-14

Development and optimisation of a qPCR assay for the enumeration of Cryptophlebia leucotreta granulovirus (CrleGV) used for commercial applications

  • Authors: Mela, Thuthula
  • Date: 2022-10-14
  • Subjects: Cryptophlebia leucotreta granulovirus , Cryptophlebia leucotreta , Late expression factor 8 (LEF-8) , Late expression factor 9 , Dark field microscopy , Genomic DNA , Polymerase chain reaction , Plasmids
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/362949 , vital:65377
  • Description: The citrus industry contributes significantly to the South African agricultural sector. Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is highly important to the South African citrus industry as it is classified as a phytosanitary pest by most international markets. Thaumatotibia leucotreta has caused an estimated annual loss of up to R100 million to the industry. In order to control T. leucotreta in South Africa, an integrated pest management (IPM) programme has been used. One of the components of this programme is Cryptophlebia leucotreta granulovirus (CrleGV), which has been formulated to a registered biopesticide namely Cryptogran and has been successfully applied in the field for over 15 years. To use CrleGV as biopesticides, quantification of the viral particles is required to perform bioassays for field trials and formulation, among other applications. Darkfield microscopy is a traditional method used for the quantification of CrleGV; however, the method is characterised as being subjective, tedious, labour intensive, and time-consuming. This study aims to develop and optimise a qPCR technique to accurately quantify CrleGV-SA OBs using plasmid DNA for downstream applications. Firstly, lef-8, lef-9, and granulin conserved genes from CrleGV-SA and CrleGV-CV3 genome sequences were analysed by performing multiple alignments to evaluate the degree of identity between these genes. This was done to design two sets of oligonucleotides (internal and external) from regions with the highest identity. Subsequently, in silico testing was done to evaluate the designed oligonucleotides to determine whether they specifically bind to the selected target regions. Secondly, three sets of DNA plasmids (pJET1.2-Gran, pJET1.2-lef-9, and pJET1.2-lef-8) were constructed, each containing a target region for either granulin, lef-9, and lef-8 genes for use as standards in a downstream qPCR assay. This was achieved by first extracting gDNA from CrleGV-SA OBs and using the gDNA as a template to PCR amplify the target regions of the selected gene regions with the designed oligonucleotides. Subsequently, the PCR amplified regions were then directly ligated into the pJET1.2/blunt vector, and the plasmids were confirmed by colony PCR, restriction enzyme digestion, and Sanger sequencing. Thirdly, two different methods of CrleGV-SA gDNA extraction were compared to determine which method has the best yields in terms of concentration. The extraction methods compared were the Quick-DNA Miniprep Plus kit according to manufacturer’s instructions (Method 1a), pre-treatment with Na2CO3 prior to using the Quick-DNA Miniprep Plus kit (Method 1b), pre- treatment with Na2CO3, and neutralisation with Tris-HCl prior to gDNA extraction using the Quick-DNA Miniprep Plus kit (Method 1c) and the CTAB method (Method 2). The gDNA concentration and purity for all samples were determined using a Nanodrop spectrophotometer. Method 1c (Na2CO3 and Tris-HCl pre-treated plus Quick-DNA Miniprep Plus kit) was the most efficient at extracting genomic DNA compared with the other methods, resulting in the highest DNA concentration in short processing time. Fourthly, plasmid standards were evaluated for use in the qPCR assay. This was done as it was important to consider the efficacy of the oligonucleotides; including the ability of the oligonucleotides to anneal to the appropriate segment of DNA without extensive formation of oligonucleotides dimers, non-specific annealing, or formation of secondary structure. In addition, it was done to ensure that highly accurate standard curves were generated. The standard curves were to be utilised in the downstream qPCR assay to determine the quantity of test samples by interpolation, reading from the values within the standard curve. Lastly, darkfield microscopy and qPCR methods of enumeration were compared to verify their accuracy and determine the most consistent and comparable method. This was achieved by quantifying the purified, crude-purified, and viral formulated CrleGV-SA suspensions using these methods. Subsequently, a statistical analysis was conducted to compare the results produced by the two enumeration methods. The obtained results showed that the granulin, lef- 8 and lef-9 qPCR values did not significantly differ from the darkfield microscopy results. The findings of this study revealed that the two assays, lef-8 qPCR and lef-9 qPCR, were more robust, sensitive, and efficient for the quantification of CrleGV-SA. Thus, this study has successfully developed a qPCR assay that is comparable with the traditional darkfield microscopy counting technique. This is the first study to use the qPCR technique to enumerate CrleGV-SA using plasmid standards. The developed qPCR assay is reliable, rapid, and cost- effective and has a great potential to be used as an alternative method to darkfield microscopy in the laboratory and commercial settings. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
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  • Date Issued: 2022-10-14

Development of biosensor systems for the detection of anti-cancer drugs and prostate cancer

  • Authors: Mwanza, Daniel
  • Date: 2022-10-14
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/365929 , vital:65803
  • Description: Thesis embargoed. Expected release date early 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
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  • Date Issued: 2022-10-14

Disentangling the role of prokaryotes in regulating export flux via suspended and sinking organic matter in the southern ocean

  • Authors: Dithugoe, Choaro David
  • Date: 2022-10-14
  • Subjects: Microbial ecology , Bioinformatics , Biochemistry , Oceanography , Metagenomics , Carbon cycle (Biogeochemistry) , Prokaryotes
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/365745 , vital:65782 , DOI https://doi.org/10.21504/10962/365745
  • Description: The role of phytoplankton in regulating atmospheric carbon dioxide in the marine environment has been the subject of extensive research. We lack, however, comparative insights regarding the functional contributions of bacteria, archaea, fungi, and viruses (the microbiota) to organic matter export especially in understudied polar marine environments such as the Southern Ocean. This knowledge deficit is in part due to the high levels of microbial diversity which obscures efforts to study the relationship between diversity and ecosystem functions including their roles in the sequestration of carbon and nitrogen. Elucidating their precise contributions to organic matter export may be central to potential ecosystems feedbacks to global climate change. We examined several factors which may influence organic matter export to depth including net primary production, phytoplankton biomass, temperature, and prokaryotic functional capacity in the Southern Ocean. A Marine Snow Catcher was used to collect suspended and sinking material 10 metres below mixed layer depth at Southern Ocean Time Series (SOTS) in autumn (March-April) and in the Atlantic sector of the Southern Ocean in winter (July-August) and spring (October-November) 2019. The suspended and sinking material was used to determine the particulate organic carbon and nitrogen concentrations which were then used to calculate fluxes and export ratio ((e-ratio) - particulate organic carbon flux divided by net primary production). Additionally, genomic DNA was extracted from the suspended and sinking material and sequenced to obtain Shotgun metagenomic data which was employed to reconstruct metagenome assembled genome (MAGs) and their functional capacity using bioinformatic tools such as DRAM. Data from the Atlantic sector of the Southern Ocean, demonstrate that net primary production and temperature were inversely related to the e-ratio which is consistent with previous findings from the northern region of the Southern Ocean. Genomic functional capacity from SOTS suggested that r-strategist (organisms adapted to live in unstable environments) bacteria (e.g., Gammaproteobacteria) were prominent in the suspended pool. By contrast, the sinking particle-pool appeared to be dominated by K- strategists (organisms adapted to stable environment). The opposite was true for the archaea. This finding (i.e., bacteria) differs from a previous study in the northern region of the Southern Ocean, showing that microbes with K-strategists were more abundant in the suspended fraction. K-strategists typically degrade sinking organic matter into suspended organic matter or dissolved organic matter reducing the organic carbon export efficiency. Furthermore, Data from the Atlantic sector of the Southern Ocean revealed that seasonal temperature changes might dictate the rate of regional prokaryotic degradation across the zones. Resulting in rapid degradation at the northerly warmer regions and slow degradation further south. The data further provide evidence of chemolithoautotrophic mechanisms, with prokaryotes harbouring key pathways, required to transform dissolved inorganic carbon into complex organic forms, including recalcitrant dissolved organic carbon. Collectively, the SOTS and Atlantic sector of the Southern Ocean data suggest that shifts in prokaryotic community structure and functional capacity may regulate (either degradation or synthesis of organic matter) carbon export to depth. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
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  • Date Issued: 2022-10-14

Don’t let the little man live in your head for free: an interpretive phenomenological analysis of seafarers with reportedly high levels of well-being

  • Authors: Brown, Lauren Natalie
  • Date: 2022-10-14
  • Subjects: Seafaring life Psychological aspects , Sailors Mental health , Well-being , Phenomenology , Work environment
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/327653 , vital:61140 , DOI 10.21504/10962/327653
  • Description: The mental health of seafarers has become a growing issue of concern and has attracted the attention of researchers in recent times. Seafarers are predominantly men, spend months at sea with little to no contact with loved ones ashore, and usually must reside in confined spaces that often contain substantial levels of noise and heat. The underlying causes of mental illness among seafarers are known. Some of the causes include sleep deprivation, occupational stress, marital/relationship problems, fatigue, the threat of piracy, psychosocial workload, loneliness, social isolation, separation from families, lack of shore leave, cultural issues, and job security. Despite these stressors, there are many men and women seafarers who flourish in the industry and enjoy their careers. Very little research has been conducted into the well-being practices of those seafarers who enjoy high levels of well-being. This study explores the lived experiences of a group of seafarers with reportedly high levels of psychological well-being, as well as their experiences of workplace stressors and mental health interventions offered by the industry. This study is an interpretive phenomenological analysis, which is epistemologically underpinned by phenomenology, hermeneutics and idiography. Results revealed four focus areas: general lived experiences across two worlds and how this relates to identity, what seafarers with reportedly high levels of psychological well-being experience as stressors, well-being practices of these seafarers and how these seafarers experience and make sense of mental health interventions they have come across. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
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  • Date Issued: 2022-10-14

Drifting towards death: a South African patient safety incident through an HFE Systems lens

  • Authors: Agar, Sarah Leigh
  • Date: 2022-10-14
  • Subjects: Patients Safety measures , Medical errors Prevention , Human engineering , Medical care South Africa
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/362716 , vital:65356
  • Description: Patient Safety Incidents (PSI) are a frequent occurrence within the South African public healthcare system wherein a patient is unnecessarily maimed, harmed, killed, or put through significant trauma, emotional or physical. These incidents have a significant impact on the performance of the system and the well-being of individuals involved. Often PSI are the result of multiple system failings that provide the necessary preconditions for the PSI to occur. Thus, to provide appropriate patient safety recommendations to address and aid in the prevention of future PSI it is necessary to apply a systems approach to PSI analysis. A systems approach supports a ‘bigger picture’ view of an incident which includes looking beyond the immediate causes of a PSI and taking the different levels of the healthcare system into consideration during incident analysis. Human Factors and Ergonomics (HFE) is at its core a systems discipline and has been successfully applied to multiple fields including healthcare. HFE offers multiple incident analysis tools grounded in systems theory. The Life Esidimeni incident, a PSI that resulted in the death of 144 MHCU, is the biggest PSI in recent South African history and is therefore an important potential case study for the application of HFE systems tools within the South African healthcare context (an area that is lacking in existing literature). The objectives of this research were to (i) Systematically uncover the causal factors that led to the outcome of the of the Life Esidimeni incident; (ii) Identify critical faults, and gaps within the healthcare system that led to the Life Esidimeni PSI; and (iii) Provide proactive recommendations for future prevention of PSI. To fulfil these objectives a descriptive case study research method design was adopted using a qualitative systems-based tool, AcciMap. The application of AcciMap to Life Esidimeni enabled both the sharp end and blunt end causal factors that contributed to the outcome of the incident to be identified. Importantly this provided insight into the critical faults and gaps of the South African public healthcare system. The results of the AcciMap indicated that there were four main broad systemic faults in the system. These broad areas were categorized as key themes, which include: (i) competency, (ii) safeguards, (iii) time pressures, and (iv) vertical integration. From these key themes recommendations aimed at addressing the critical faults and gaps in the system and preventing future PSI were made. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
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  • Date Issued: 2022-10-14

Dual and targeted photodynamic therapy ablation of bacterial and cancer cells using phthalocyanines and porphyrins in the presence of carbon-based nanomaterials

  • Authors: Openda, Yolande Ikala
  • Date: 2022-10-14
  • Subjects: Phthalocyanines , Porphyrins , Active oxygen , Biofilms , Breast Cancer Treatment , Nanostructured materials , Combination therapy , Photochemotherapy
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/365945 , vital:65804 , DOI https://doi.org/10.21504/10962//365946
  • Description: Phthalocyanines (Pcs) and porphyrins bearing substituents that possess antibacterial/anticancer properties are used as photosensitizers (PS) for the first time in the work. For targeting specificity and improved photoactivity, the PSs were afterward functionalized with carbon nanomaterials such as graphene quantum dots (GQDs) and detonation nanodiamonds (DNDs) via covalent conjugation (amide or ester bonds) or by non-covalent conjugation (π-π stacking and electrostatic interactions). Furthermore, the PSs-DNDs nanoconjugates were conjugated to either chitosan-capped silver nanoparticles (CSAg) via amide bonds or to the bare silver nanoparticles (Ag NPs) using the silver- nitrogen affinity. The as-synthesized nanoconjugates were also fully characterized by spectroscopic and microscopic methods together with thermal analysis. The potential photocytotoxicity of the complexes alone and their nanoconjugates against S. aureus and/or E. coli planktonic and biofilm cultures has been evaluated in vitro. Compared to the non- quaternized PSs, the cationic analogs exhibited a higher photodynamic inactivation against the planktonic cells with log10 reduction values above 9 in the viable count using a concentration of ca. 1.25 μM following 30 min exposure to light (Light dose: 943 J/cm2 for Pcs and 250 mW/cm2 for porphyrins). Whereas, at a concentration of ca. 100 μM the cationic PSs showed complete eradication of biofilms upon 30 min exposure to light. As a result of conjugation to carbon-based nanomaterials and silver nanoparticles, the compounds proved to be more effective as they exhibited stronger antibacterial and anti-biofilm activities on the multi-drug resistant bacteria strains due to synergetic effect, compared to PSs alone. This suggests that the newly prepared nanohybrids (PS concentration ca. 100 μM) could be used as potential antimicrobial agents in the treatment of biofilm-related infections. The target nanoconjugates showed all the advantages of two different groups existing on a single entity. In light of the potential advantages of combined chemotherapy and photodynamic antimicrobial chemotherapy (PACT), this work reports for the first time the use of PACT-ciprofloxacin (CIP) dual therapy using selected indium quaternized PSs which showed higher photoactivity with complete eradication of both Gram-positive and Gram-negative bacteria biofilms at concentrations of 8 μM of PS versus 2 μg/mL of the antibiotic following 15 min irradiation time (light dose: 471 J/cm2 for Pcs and fluence: 250 mW/cm2 for porphyrins) on S. aureus. Whereas the total killing of E. coli was obtained when combining 8 or 16 μM of PS combined with 4 μg/mL of CIP. The combined treatment resulted in the complete eradication of the matured biofilms with the highest log10 reduction values of 7.05 and 7.20 on S. aureus and E. coli, respectively. Used as a model, positively charged dimethylamino-chalcone Pcs also exhibited interesting photodynamic therapy (PDT) activity against MCF-7 cancer cells giving IC50 values of 17.9 and 7.4 μM, respectively following 15 min irradiation. Additionally, the TD-B3LYP/LanL2DZ calculations were run on the dimethylaminophenyl- porphyrins to compare the singlet excitation energies of quaternized and non-quaternized porphyrins in vacuo. the study shows excellent agreement between time-dependent density- functional theory (TD-DFT) exciting energies and the experimental S1>S0 excitation energies. The small deviation observed between the calculated and experimental spectra arises from the solvent effect. The excitation energies observed in these UV-Vis spectra mostly originated from electron promotion between the highest occupied molecular orbital (HOMO) for the less intense band and the HOMO-1 for the most intense band of the ground states to the lower unoccupied molecular orbital (LUMO) of the excited states. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
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  • Date Issued: 2022-10-14

Effect of Helicosporidium sp. (Chlorophyta; Trebouxiophyceae) infection on Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), a biological control agent for the invasive Salvinia molesta D.S. Mitchell (Salviniaceae) in South

  • Authors: Mphephu, Tshililo Emmanuel
  • Date: 2022-10-14
  • Subjects: Salvinia molesta South Africa , Weeds Biological control , Cyrtobagous salviniae , Ketoconazole
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/365815 , vital:65792 , DOI https://doi.org/10.21504/10962/365815
  • Description: The effectiveness of established biological control agents depends on biotic and abiotic interactions in the introduced range. The weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), was released as a biological control against Salvinia molesta D.S. Mitchell (Salviniaceae) in South Africa in 1985. This agent has been highly successful against S. molesta and has significantly reduced the weed’s populations around the country. However, in 2007, the parasitic alga, Helicosporidium sp. (an undescribed species), was detected in field-collected C. salviniae adults in South Africa. The distribution and impacts of this disease on the weevil and its efficacy as a control agent were not known. In this thesis, the prevalence, infection load, and impact of Helicosporidium sp. on C. salviniae was determined. In 2019, adult weevils were collected from 10 sites across the Eastern Cape, KwaZulu-Natal, Limpopo, and Western Cape provinces and screened to determine the occurrence, infection load, and geographic distribution of Helicosporidium sp. Transmission mechanisms of this disease in C. salviniae were then evaluated. The possible impact of Helicosporidium sp. was assessed by comparing the feeding rates and the reproductive output of the diseased and healthy adults of C. salviniae. An attempt was then made to eliminate the disease in C. salviniae through the application of the antibiotic, ketoconazole. Further, the role of temperature on infection load in C. salviniae was also assessed. Finally, recommendations for the long-term biological control programme against S. molesta in South Africa were made. The disease covers the entire distribution range of C. salviniae in South Africa, with the disease occurrence rate ranging from 92.15% to 100% insects infected per site. Helicosporidium sp. was found to transmit vertically within the populations of C. salviniae. Infection by the Helicosporidium sp. disease reduced the reproductive output of C. salviniae as well its impact on biomass reduction of S. molesta when a diseased culture was compared to a healthy culture from the USA. 98.44 to 98.55% of Helicosporidium sp. loads were reduced through multiple applications of ketoconazole concentrations under in vitro trials. In vivo treatments resulted in 70% control of Helicosporidium sp. in the adults of C. salviniae that were fed ketoconazole three times over a 21 day period. Adult C. salviniae feeding and survival performances were similar when fed fronds of S. molesta inoculated with ketoconazole and water. The lowest and highest disease loads of Helicosporidium sp. were recorded when the weevils were reared at 30°C and 14°C, respectively. As expected, the highest impact and reproductive output of C. salviniae were at 30°C. The evaluations discussed in this thesis highlight the role of diseases in biological control agents, and gaps in both the pre-release and post-release monitoring that should integrate screening of diseases in these studies. Although the combined application of the antibiotic and temperature will reduce Helicosporidium sp. loads and impact, this technology is most likely only applicable where the weevils are reared in small numbers in a rearing facility and not really applicable to the field situation. It is important to release healthy agents that will cause efficient control of the target weed plant species, therefore, when introducing new biological control agents, the health status of such agents needs to be understood. Therefore, long-term field monitoring and assessment of the impact of C. salviniae on S. molesta should be conducted to track all the changes that may result due to the presence of Helicosporidium sp. This long-term monitoring and assessment will give a more informative role of Helicosporidium sp. in field populations of C. salviniae. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
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  • Date Issued: 2022-10-14

Electrocatalytic activity of symmetric and asymmetric Co(II) and Mn(III) porphyrins in the presence of graphene quantum dots towards the oxidation of hydrazine

  • Authors: Jokazi, Mbulelo
  • Date: 2022-10-14
  • Subjects: Electrocatalysis , Hydrazine , Quantum dots , Graphene , Porphyrins
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/362894 , vital:65372
  • Description: The influence of metal porphyrins in electro-oxidation of hydrazine is explored. A series of symmetric and asymmetric porphyrins alone and in the presence of graphene quantum dots (GQDs) are employed in this work. Tetra 4-aminophenyl porphyrin, manganese tetra 4-aminophenyl porphyrin, manganese tetra 4-aminophenyl porphyrin--GQDs, and manganese tetra 4-aminophenyl porphyrin@GQDs are the symmetric porphyrins. The asymmetric porphyrin and composites are 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins, manganese 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins, cobalt 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins, manganese 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins--GQDs, and cobalt 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins--GQDs. These complexes were synthesized and characterized accordingly and applied for electrocatalysis. The electrocatalytic experiments were carried out using glassy carbon electrode and the modification was through drop-dry method. The porphyrin and GQDs synthesized were characterized using UV-Vis spectroscopy, Mass spectrometry, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. The modified electrodes were characterized using cyclic voltammetry and electrochemical Impedance spectroscopy. The introduction of metal ion in the center of the porphyrin improved electrocatalysis. The presence of push-pull substituents in the porphyrin lowered the oxidation potential and improved the catalysis. The presence of GQDs improved catalysis in both symmetric and asymmetric porphyrin compared to individual components. Cobalt porphyrins showed better activity than manganese porphyrin. , Thesis (MSc) -- Faculty of Science, Chemistry, 2022
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  • Date Issued: 2022-10-14

Elele nje usathetha: Ukukhapha as an expression of amaXhosa language world-sense

  • Authors: Dana, Zikho
  • Date: 2022-10-14
  • Subjects: Xhosa language Discourse analysis , Guides (Spiritualism) , Grief Religious aspects , Historical linguistics , Xhosa language Religious aspects , Xhosa (African people) Death , Death Religious aspects
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/406309 , vital:70257
  • Description: This study examines ukukhapha as an expression of amaXhosa language world-sense. Firstly, it examines how ukukhapha as a rite of passage to accompany the spirit of the deceased from the physical realm into the spiritual realm maintains the nexus between the living and the dead. Secondly, it explores ukukhapha as a ritual of collective mourning. Both dimensions of the study are pursued using language as a point of departure. This study draws on four key texts written across different times in history, namely: Intlalo kaXhosa (The Social Life of amaXhosa) by Tiyo Burnside (TB) Soga (1974); the three volume Greater Dictionary of isiXhosa (1989, 2003 and 2006); Nokuzola Mndende’s (2002) PhD thesis entitled: Signifying practices: AmaXhosa ritual speech; and Khaya Dlanga’s (2015) memoire: To Quote Myself. This thesis examines ukukhapha in the context of death to establish how amaXhosa speak about death and how this shapes their understanding and its practice. Discourse analysis is employed to clarify some practices and examples of ukukhapha. It’s also used to trace the evolution of ukukhapha over time in isiXhosa. It is utilized as a reservoir of knowledge epitomizing the world-sense of amaXhosa rather than solely as a means of communication. This study reveals that while ukukhapha as a ritual slaughtering of an ox to accompany the deceased is found in literature, its examination as a practice of communal and collective grief is scanty. The four key texts studied in this thesis reveal that ukukhapha goes beyond a mere ritual slaughtering of a sacrificial beast to accompany the spirit of the deceased to the ancestral realm. It is a practice that has allowed amaXhosa to collectively grief. Furthermore, it has provided the bereaved various forms of support which are pivotal in maintaining and strengthening kinship and communal ties among the living. This study further reveals that for the Africans in general, and for amaXhosa in particular, death is not the end of life. It is a continuation of life where the deceased morphs and graduates to an ancestor who joins a larger community of ancestors who act as intermediaries between the living and uMdali, the Creator. The findings demonstrate that through ukukhapha, there is no bifurcation between gender and age, rather they complement each other as the successful execution of the mourning period and farewell of a loved one is dependent on the roles played by both women and men respectively. , Olu phando luceba ukuphonononga ukukhapha njengendlela yokuphila equlathwe kulwimi lwamaXhosa. Okokuqala, luzakuphanda indlela ukukhapha njengesiko lokukhapha umphefumlo womfi ukusukela kwelenyama ukuya kwelemimoya kugcina ngayo ubudlelwane phakathi kwabaphilayo nabaleli ukuthula. Okwesibini, luzakuphanda ukukhapha njengesiko lokuzila ndawoni nye. Zombini ezi nkalo zizakuvelelwa ngokugxila kulwimi. Olu phando lucaphula kwimibhalo emine engundoqo kumaxesha ohlukileyo kwimbali, iquka: Intlalo kaXhosa owabhalwa nguTiyo Burnside Soga (ngowe1974); isichazi-magama esinemiqulu emithathu iThe Greater Dictionary of isiXhosa (ngowama-1989, owama-2003 nowama-2006); ithisisi yePhD kaNokuzola Mndende (ngowama-2002) ebizwa Signifying practices: amaXhosa ritual speech; nencwadi engunomalisa wobom, ebhalwe nguKhaya Dlanga (ngowama-2015) ebizwa To Quote Myself. Le thisisi isebenzisa ukukhapha kwilixa lokufa ukuphanda indlela amaXhosa athetha ngkufa, nokuba le ndlela yokuthetha iyichaphazela njani indlela abakuqonda ngayo ukufa nendlela abakhaphana ngayo. IDiscourse Analysis isetyenziswa njengesixhobo sokucacisa ukukhapha. Iphinde isetyenziswe ukunika imizekelo yeli siko nendlela yokuphila kwakunye nendlela ukukhapha kutshintshe ngayo ekuhambeni kwexesha kulwimi lwesiXhosa njengokuba sizakusetyenziswa njengovimba wolwazi, endaweni yokusetyenziswa njengesixhobo sonxibelelwano kuphela. Olu phando lubonisa ukuba njengokuba ukukhapha njengesiko lokuphalaza igazi lenkomo ukukhapha umfi kubhaliwe ngako kuncwadi, indlela abaphilayo enyameni abakhaphana ngayo iyasilela kuncwadi. Le mibhalo mine echongiweyo nephononongiweyo kolu phando ivelisa ukuba ukukhapha akuphelelanga ekuphalazeni igazi lenkomo kuphela njengesiko lokukhapha umfi ukuze awelele kweleminyanya, yindlela eyavumela amaXhosa ukuba azile ngemanyano apho uluntu luxhasa abafelweyo ngeendlela ezahlukeneyo ezithi zomeleze imanyano phakathi kwabazalanayo noluntu lwabaphilayo. Olu phando lutyhila into yokuba kumaAfrika jikelele, ingakumbi amaXhosa, ukufa ayikuko ukuphela kobom, nto nje luhambo olugqithisa umfi kubom obulandelayo apho ongeza kwinani kwelezinyanya apho izinyanya zilikhonco phakathi koMdali nabaphilayo. Iziphumo ngokukhapha zibonisa ukuba akukho ukuchasana phakathi kwesini neminyaka, nto nje, le miba mibini iyathungelana ekuncediseni nasekuqinisekiseni ukuba abafazi namadoda benza iindima zabo ngokufanelekileyo ekuqinisekiseni ukuba ixesha lezila nokubeka umfi kwikhaya lakhe lokugqibela ziyimpumelelo. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2022
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  • Date Issued: 2022-10-14

Evaluating the role of Stress Induced Phosphoprotein 1 isoforms in Kaposi's Sarcoma-Associated Herpesvirus biology

  • Authors: Ruck, Duncan Kyle
  • Date: 2022-10-14
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/365280 , vital:65723
  • Description: Thesis embargoed. Possible release date set for early 2025. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
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  • Date Issued: 2022-10-14
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